feat: give plugins their own settings and one settings screen

src/backend/database/db/index.ts

@@ -751,6 +751,21 @@ async function initializeCompleteDatabase(): Promise<void> {
         FOREIGN KEY (plugin_id) REFERENCES plugins (id) ON DELETE CASCADE
     );
 
+    CREATE TABLE IF NOT EXISTS plugin_settings (
+        id INTEGER PRIMARY KEY AUTOINCREMENT,
+        plugin_id TEXT NOT NULL,
+        scope TEXT NOT NULL,
+        scope_id TEXT,
+        key TEXT NOT NULL,
+        value TEXT,
+        encrypted INTEGER NOT NULL DEFAULT 0,
+        updated_at TEXT NOT NULL DEFAULT CURRENT_TIMESTAMP,
+        UNIQUE (plugin_id, scope, scope_id, key),
+        FOREIGN KEY (plugin_id) REFERENCES plugins (id) ON DELETE CASCADE
+    );
+
+    CREATE INDEX IF NOT EXISTS idx_plugin_settings_plugin_scope ON plugin_settings (plugin_id, scope);
+
     CREATE TABLE IF NOT EXISTS rbac_known_permissions (
         id INTEGER PRIMARY KEY AUTOINCREMENT,
         permission TEXT NOT NULL,

src/backend/database/db/schema.mysql.ts

@@ -2252,6 +2252,49 @@ export const pluginStorage = mysqlTable(
   ],
 );
 
+/**
+ * Values for the settings fields a plugin declares in contributes.settings.
+ *
+ * scope_id is polymorphic: null for admin scope, a user id for user scope, a
+ * host id rendered as text for host scope. That is why it carries no foreign
+ * key - one column cannot point at two tables - so the user and host delete
+ * paths remove these rows explicitly. Cascading with the plugin is a real FK,
+ * because uninstalling should leave nothing behind.
+ *
+ * Secret fields are encrypted with the system key before they land here, and
+ * `encrypted` records which rows that applies to so a read knows to decrypt.
+ */
+export const pluginSettings = mysqlTable(
+  "plugin_settings",
+  {
+    id: int("id").autoincrement().primaryKey(),
+    pluginId: varchar("plugin_id", { length: 255 })
+      .notNull()
+      .references(() => plugins.id, { onDelete: "cascade" }),
+    /** admin | user | host */
+    scope: varchar("scope", { length: 255 }).notNull(),
+    scopeId: varchar("scope_id", { length: 255 }),
+    key: varchar("key", { length: 255 }).notNull(),
+    /** JSON-encoded, so a field keeps its declared type across a round trip. */
+    value: text("value"),
+    encrypted: boolean("encrypted")
+      .notNull()
+      .default(false),
+    updatedAt: varchar("updated_at", { length: 255 })
+      .notNull()
+      .default(sql`(CURRENT_TIMESTAMP)`),
+  },
+  (table) => [
+    uniqueIndex("idx_plugin_settings_scope_key").on(
+      table.pluginId,
+      table.scope,
+      table.scopeId,
+      table.key,
+    ),
+    index("idx_plugin_settings_plugin_scope").on(table.pluginId, table.scope),
+  ],
+);
+
 /**
  * Which of a plugin's migrations have been applied.
  *

src/backend/database/db/schema.pg.ts

@@ -2253,6 +2253,49 @@ export const pluginStorage = pgTable(
   ],
 );
 
+/**
+ * Values for the settings fields a plugin declares in contributes.settings.
+ *
+ * scope_id is polymorphic: null for admin scope, a user id for user scope, a
+ * host id rendered as text for host scope. That is why it carries no foreign
+ * key - one column cannot point at two tables - so the user and host delete
+ * paths remove these rows explicitly. Cascading with the plugin is a real FK,
+ * because uninstalling should leave nothing behind.
+ *
+ * Secret fields are encrypted with the system key before they land here, and
+ * `encrypted` records which rows that applies to so a read knows to decrypt.
+ */
+export const pluginSettings = pgTable(
+  "plugin_settings",
+  {
+    id: serial("id").primaryKey(),
+    pluginId: varchar("plugin_id", { length: 255 })
+      .notNull()
+      .references(() => plugins.id, { onDelete: "cascade" }),
+    /** admin | user | host */
+    scope: varchar("scope", { length: 255 }).notNull(),
+    scopeId: varchar("scope_id", { length: 255 }),
+    key: varchar("key", { length: 255 }).notNull(),
+    /** JSON-encoded, so a field keeps its declared type across a round trip. */
+    value: text("value"),
+    encrypted: boolean("encrypted")
+      .notNull()
+      .default(false),
+    updatedAt: varchar("updated_at", { length: 255 })
+      .notNull()
+      .default(sql`CURRENT_TIMESTAMP`),
+  },
+  (table) => [
+    uniqueIndex("idx_plugin_settings_scope_key").on(
+      table.pluginId,
+      table.scope,
+      table.scopeId,
+      table.key,
+    ),
+    index("idx_plugin_settings_plugin_scope").on(table.pluginId, table.scope),
+  ],
+);
+
 /**
  * Which of a plugin's migrations have been applied.
  *

src/backend/database/db/schema.ts

@@ -2251,6 +2251,49 @@ export const pluginStorage = sqliteTable(
   ],
 );
 
+/**
+ * Values for the settings fields a plugin declares in contributes.settings.
+ *
+ * scope_id is polymorphic: null for admin scope, a user id for user scope, a
+ * host id rendered as text for host scope. That is why it carries no foreign
+ * key - one column cannot point at two tables - so the user and host delete
+ * paths remove these rows explicitly. Cascading with the plugin is a real FK,
+ * because uninstalling should leave nothing behind.
+ *
+ * Secret fields are encrypted with the system key before they land here, and
+ * `encrypted` records which rows that applies to so a read knows to decrypt.
+ */
+export const pluginSettings = sqliteTable(
+  "plugin_settings",
+  {
+    id: integer("id").primaryKey({ autoIncrement: true }),
+    pluginId: text("plugin_id")
+      .notNull()
+      .references(() => plugins.id, { onDelete: "cascade" }),
+    /** admin | user | host */
+    scope: text("scope").notNull(),
+    scopeId: text("scope_id"),
+    key: text("key").notNull(),
+    /** JSON-encoded, so a field keeps its declared type across a round trip. */
+    value: text("value"),
+    encrypted: integer("encrypted", { mode: "boolean" })
+      .notNull()
+      .default(false),
+    updatedAt: text("updated_at")
+      .notNull()
+      .default(sql`CURRENT_TIMESTAMP`),
+  },
+  (table) => [
+    uniqueIndex("idx_plugin_settings_scope_key").on(
+      table.pluginId,
+      table.scope,
+      table.scopeId,
+      table.key,
+    ),
+    index("idx_plugin_settings_plugin_scope").on(table.pluginId, table.scope),
+  ],
+);
+
 /**
  * Which of a plugin's migrations have been applied.
  *

src/backend/database/repositories/factory.ts

@@ -34,6 +34,7 @@ import { OpenTabRepository } from "./open-tab-repository.js";
 import { OpksshTokenRepository } from "./opkssh-token-repository.js";
 import { PluginRepository } from "./plugin-repository.js";
 import { PluginStorageRepository } from "./plugin-storage-repository.js";
+import { PluginSettingsRepository } from "./plugin-settings-repository.js";
 import { PluginMigrationRepository } from "./plugin-migration-repository.js";
 import { PluginPermissionGrantRepository } from "./plugin-permission-grant-repository.js";
 import { PluginRegistryRepository } from "./plugin-registry-repository.js";
@@ -395,6 +396,13 @@ export function createCurrentPluginStorageRepository(): PluginStorageRepository
   );
 }
 
+export function createCurrentPluginSettingsRepository(): PluginSettingsRepository {
+  return new PluginSettingsRepository(
+    createCurrentRepositoryContext(),
+    createCurrentRepositoryWriteHook("plugin_settings_repository_write"),
+  );
+}
+
 export function createCurrentPluginMigrationRepository(): PluginMigrationRepository {
   return new PluginMigrationRepository(
     createCurrentRepositoryContext(),

src/backend/database/repositories/host-repository.ts

@@ -1,6 +1,6 @@
 import { and, eq, inArray, sql } from "drizzle-orm";
 import { randomUUID } from "crypto";
-import { hostAccess, hosts } from "../db/schema.js";
+import { hostAccess, hosts, pluginSettings } from "../db/schema.js";
 import type { DatabaseContext } from "./database-context.js";
 import { DataCrypto } from "../../utils/data-crypto.js";
 import { rowsAffected } from "./mutation-result.js";
@@ -338,6 +338,25 @@ export class HostRepository {
   }
 
   async deleteByUserId(userId: string): Promise<number> {
+    // Bulk path, so it never passes through deleteAccessForHost: clear the
+    // host-scope plugin settings for these hosts before the rows go.
+    const owned = await this.context.drizzle
+      .select({ id: hosts.id })
+      .from(hosts)
+      .where(eq(hosts.userId, userId));
+
+    if (owned.length > 0) {
+      await this.context.drizzle.delete(pluginSettings).where(
+        and(
+          eq(pluginSettings.scope, "host"),
+          inArray(
+            pluginSettings.scopeId,
+            owned.map((row) => String(row.id)),
+          ),
+        ),
+      );
+    }
+
     const result = await this.context.drizzle
       .delete(hosts)
       .where(eq(hosts.userId, userId));
@@ -350,6 +369,18 @@ export class HostRepository {
   }
 
   async deleteAccessForHost(hostId: number): Promise<number> {
+    // plugin_settings.scope_id is polymorphic, so it has no foreign key to
+    // ssh_data and the engine will not cascade it. Cleared alongside the
+    // access rows, which every host delete path already goes through.
+    await this.context.drizzle
+      .delete(pluginSettings)
+      .where(
+        and(
+          eq(pluginSettings.scope, "host"),
+          eq(pluginSettings.scopeId, String(hostId)),
+        ),
+      );
+
     const result = await this.context.drizzle
       .delete(hostAccess)
       .where(eq(hostAccess.hostId, hostId));

src/backend/database/repositories/plugin-settings-repository.ts

@@ -0,0 +1,191 @@
+import { and, eq, inArray, isNull } from "drizzle-orm";
+import { pluginSettings } from "../db/schema.js";
+import type { DatabaseContext } from "./database-context.js";
+import { rowsAffected } from "./mutation-result.js";
+import { insertReturning, updateReturning } from "./returning.js";
+
+export type PluginSettingsRecord = typeof pluginSettings.$inferSelect;
+
+export type PluginSettingsScope = "admin" | "user" | "host";
+
+/**
+ * Values behind ctx.settings and the /plugins/:id/settings routes.
+ *
+ * scope_id is null for admin scope, so every lookup has to use IS NULL rather
+ * than = NULL: SQL equality against null never matches, which would make an
+ * admin setting look unset no matter how often it was written.
+ */
+export class PluginSettingsRepository {
+  constructor(
+    private readonly context: DatabaseContext,
+    private readonly onWrite?: () => void | Promise<void>,
+  ) {}
+
+  private scopeMatch(
+    pluginId: string,
+    scope: PluginSettingsScope,
+    scopeId: string | null,
+  ) {
+    return and(
+      eq(pluginSettings.pluginId, pluginId),
+      eq(pluginSettings.scope, scope),
+      scopeId === null
+        ? isNull(pluginSettings.scopeId)
+        : eq(pluginSettings.scopeId, scopeId),
+    );
+  }
+
+  async get(
+    pluginId: string,
+    scope: PluginSettingsScope,
+    scopeId: string | null,
+    key: string,
+  ): Promise<PluginSettingsRecord | null> {
+    const rows = await this.context.drizzle
+      .select()
+      .from(pluginSettings)
+      .where(
+        and(
+          this.scopeMatch(pluginId, scope, scopeId),
+          eq(pluginSettings.key, key),
+        ),
+      )
+      .limit(1);
+
+    return rows[0] ?? null;
+  }
+
+  async getAll(
+    pluginId: string,
+    scope: PluginSettingsScope,
+    scopeId: string | null,
+  ): Promise<PluginSettingsRecord[]> {
+    return this.context.drizzle
+      .select()
+      .from(pluginSettings)
+      .where(this.scopeMatch(pluginId, scope, scopeId));
+  }
+
+  /**
+   * Every row for a set of scope ids, in one query.
+   *
+   * The host list would otherwise run one query per host, which is the shape
+   * that made other list endpoints slow at a few hundred hosts.
+   */
+  async getAllForScopeIds(
+    scope: PluginSettingsScope,
+    scopeIds: string[],
+  ): Promise<PluginSettingsRecord[]> {
+    if (scopeIds.length === 0) return [];
+
+    return this.context.drizzle
+      .select()
+      .from(pluginSettings)
+      .where(
+        and(
+          eq(pluginSettings.scope, scope),
+          inArray(pluginSettings.scopeId, scopeIds),
+        ),
+      );
+  }
+
+  async set(
+    pluginId: string,
+    scope: PluginSettingsScope,
+    scopeId: string | null,
+    key: string,
+    value: string | null,
+    encrypted = false,
+    now = new Date().toISOString(),
+  ): Promise<void> {
+    const where = and(
+      this.scopeMatch(pluginId, scope, scopeId),
+      eq(pluginSettings.key, key),
+    )!;
+
+    const existing = await this.context.drizzle
+      .select()
+      .from(pluginSettings)
+      .where(where)
+      .limit(1);
+
+    if (existing[0]) {
+      await updateReturning(
+        this.context,
+        pluginSettings,
+        { value, encrypted, updatedAt: now },
+        where,
+      );
+    } else {
+      await insertReturning(this.context, pluginSettings, {
+        pluginId,
+        scope,
+        scopeId,
+        key,
+        value,
+        encrypted,
+        updatedAt: now,
+      });
+    }
+
+    await this.afterWrite();
+  }
+
+  async delete(
+    pluginId: string,
+    scope: PluginSettingsScope,
+    scopeId: string | null,
+    key: string,
+  ): Promise<boolean> {
+    const result = await this.context.drizzle
+      .delete(pluginSettings)
+      .where(
+        and(
+          this.scopeMatch(pluginId, scope, scopeId),
+          eq(pluginSettings.key, key),
+        ),
+      );
+
+    const affected = rowsAffected(result) > 0;
+    if (affected) await this.afterWrite();
+    return affected;
+  }
+
+  async deleteByPlugin(pluginId: string): Promise<number> {
+    const result = await this.context.drizzle
+      .delete(pluginSettings)
+      .where(eq(pluginSettings.pluginId, pluginId));
+
+    const affected = rowsAffected(result);
+    if (affected > 0) await this.afterWrite();
+    return affected;
+  }
+
+  /**
+   * Removes every plugin's rows for one user or host.
+   *
+   * scope_id carries no foreign key, so the user and host delete paths call
+   * this instead of relying on the engine to cascade.
+   */
+  async deleteByScope(
+    scope: PluginSettingsScope,
+    scopeId: string,
+  ): Promise<number> {
+    const result = await this.context.drizzle
+      .delete(pluginSettings)
+      .where(
+        and(
+          eq(pluginSettings.scope, scope),
+          eq(pluginSettings.scopeId, scopeId),
+        ),
+      );
+
+    const affected = rowsAffected(result);
+    if (affected > 0) await this.afterWrite();
+    return affected;
+  }
+
+  private async afterWrite(): Promise<void> {
+    await this.onWrite?.();
+  }
+}

src/backend/database/repositories/user-repository.ts

@@ -1,5 +1,5 @@
-import { asc, eq, inArray, like, sql } from "drizzle-orm";
-import { users } from "../db/schema.js";
+import { and, asc, eq, inArray, like, sql } from "drizzle-orm";
+import { pluginSettings, users } from "../db/schema.js";
 import type { DatabaseContext } from "./database-context.js";
 import {
   countValue,
@@ -199,6 +199,15 @@ export class UserRepository {
   }
 
   async delete(id: string): Promise<boolean> {
+    // plugin_settings.scope_id is polymorphic, so it carries no foreign key to
+    // users and the engine will not cascade it. Removed here rather than in a
+    // route so every caller that deletes a user is covered.
+    await this.context.drizzle
+      .delete(pluginSettings)
+      .where(
+        and(eq(pluginSettings.scope, "user"), eq(pluginSettings.scopeId, id)),
+      );
+
     const result = await this.context.drizzle
       .delete(users)
       .where(eq(users.id, id));

src/backend/database/routes/host-plugin-settings.ts

@@ -0,0 +1,130 @@
+/**
+ * The pluginSettings map attached to a host on its way out.
+ *
+ * Without this the host editor would need one request per plugin per host,
+ * which is the shape that makes a list of a few hundred hosts slow. One query
+ * covers the whole list instead.
+ *
+ * Kept out of transformHostResponse because that function is synchronous and
+ * shared by every host read path. Secrets are always redacted here, so nothing
+ * on this path has to decrypt and the async work stays in one place.
+ */
+
+import type { PluginManifest } from "@termix/plugin-sdk/manifest";
+import { createCurrentPluginSettingsRepository } from "../repositories/factory.js";
+import type { PluginSettingsRecord } from "../repositories/plugin-settings-repository.js";
+import { declaredFields, resolveFieldValue } from "../../plugins/settings.js";
+import { getPluginRuntime } from "../../plugins/index.js";
+import { sshLogger } from "../../utils/logger.js";
+
+export type HostPluginSettings = Record<string, Record<string, unknown>>;
+
+/** Enabled plugins that declare host-scope settings, with their manifests. */
+function hostSettingsPlugins(): PluginManifest[] {
+  try {
+    const { loader } = getPluginRuntime();
+    return loader
+      .list()
+      .filter((plugin) => plugin.state === "active")
+      .map((plugin) => plugin.manifest)
+      .filter(
+        (manifest): manifest is PluginManifest =>
+          !!manifest && !!manifest.contributes?.settings?.host,
+      );
+  } catch {
+    // The runtime is not up in every context that renders a host.
+    return [];
+  }
+}
+
+/**
+ * Builds the map for a set of hosts in one query.
+ *
+ * Returns an empty map when no enabled plugin declares host settings, so the
+ * common case costs nothing.
+ */
+export async function loadHostPluginSettings(
+  hostIds: number[],
+): Promise<Map<number, HostPluginSettings>> {
+  const result = new Map<number, HostPluginSettings>();
+  const manifests = hostSettingsPlugins();
+  if (manifests.length === 0 || hostIds.length === 0) return result;
+
+  let rows: PluginSettingsRecord[] = [];
+  try {
+    rows = await createCurrentPluginSettingsRepository().getAllForScopeIds(
+      "host",
+      hostIds.map(String),
+    );
+  } catch (error) {
+    // A host list must not fail because a settings read did.
+    sshLogger.warn("Failed to load host plugin settings", {
+      operation: "host_plugin_settings",
+      error: error instanceof Error ? error.message : String(error),
+    });
+    return result;
+  }
+
+  const byHostAndPlugin = new Map<string, PluginSettingsRecord[]>();
+  for (const row of rows) {
+    const key = `${row.scopeId}:${row.pluginId}`;
+    const list = byHostAndPlugin.get(key);
+    if (list) list.push(row);
+    else byHostAndPlugin.set(key, [row]);
+  }
+
+  for (const hostId of hostIds) {
+    const perPlugin: HostPluginSettings = {};
+
+    for (const manifest of manifests) {
+      const fields = declaredFields(manifest, "host");
+      if (fields.length === 0) continue;
+
+      const stored = new Map(
+        (byHostAndPlugin.get(`${hostId}:${manifest.id}`) ?? []).map((row) => [
+          row.key,
+          row,
+        ]),
+      );
+
+      const values: Record<string, unknown> = {};
+      for (const field of fields) {
+        values[field.key] = await resolveFieldValue(
+          field,
+          stored.get(field.key),
+          { redactSecrets: true },
+        );
+      }
+      perPlugin[manifest.id] = values;
+    }
+
+    if (Object.keys(perPlugin).length > 0) result.set(hostId, perPlugin);
+  }
+
+  return result;
+}
+
+/** Attaches the map to already-transformed host objects, in place. */
+export function attachHostPluginSettings(
+  hosts: Record<string, unknown>[],
+  settings: Map<number, HostPluginSettings>,
+): void {
+  if (settings.size === 0) return;
+  for (const host of hosts) {
+    const hostId = Number(host.id);
+    const values = settings.get(hostId);
+    if (values) host.pluginSettings = values;
+  }
+}
+
+/** The single-host convenience wrapper. */
+export async function withHostPluginSettings(
+  host: Record<string, unknown>,
+): Promise<Record<string, unknown>> {
+  const hostId = Number(host.id);
+  if (!Number.isInteger(hostId)) return host;
+
+  const settings = await loadHostPluginSettings([hostId]);
+  const values = settings.get(hostId);
+  return values ? { ...host, pluginSettings: values } : host;
+}

src/backend/database/routes/host.ts

@@ -45,6 +45,11 @@ import {
   stripSensitiveFields,
   transformHostResponse,
 } from "./host-normalizers.js";
+import {
+  attachHostPluginSettings,
+  loadHostPluginSettings,
+  withHostPluginSettings,
+} from "./host-plugin-settings.js";
 import { validateParentHostId } from "./host-parent-validation.js";
 import { registerHostOpksshRoutes } from "./host-opkssh-routes.js";
 import { registerHostStepCaRoutes } from "./host-step-ca-routes.js";
@@ -1701,6 +1706,18 @@ router.get(
             )
           : stripSensitiveFields(host),
       );
+
+      // After sanitizing: the connect-level projection reduces a shared host
+      // to an allowlist, which would drop this again. One query for the list.
+      attachHostPluginSettings(
+        sanitized,
+        await loadHostPluginSettings(
+          sanitized
+            .map((host) => Number(host.id))
+            .filter((id) => Number.isInteger(id)),
+        ),
+      );
+
       res.json(sanitized);
     } catch (err) {
       sshLogger.error("Failed to fetch SSH hosts from database", err, {
@@ -1767,7 +1784,9 @@ router.get(
         const resolved =
           (await resolveHostCredentials(result, userId)) || result;
 
-        return res.json(stripSensitiveFields(resolved));
+        return res.json(
+          await withHostPluginSettings(stripSensitiveFields(resolved)),
+        );
       }
 
       // Not the owner: shared recipients get a sanitized view of the host.
@@ -1818,9 +1837,11 @@ router.get(
         (await resolveHostCredentials(sharedResult, userId)) || sharedResult;
 
       res.json(
-        sanitizeHostForRecipient(
-          resolvedSharedResult,
-          accessInfo.permissionLevel,
+        await withHostPluginSettings(
+          sanitizeHostForRecipient(
+            resolvedSharedResult,
+            accessInfo.permissionLevel,
+          ),
         ),
       );
     } catch (err) {

src/backend/database/routes/plugins.ts

@@ -14,9 +14,29 @@ import {
 } from "../repositories/factory.js";
 import { getPluginRuntime } from "../../plugins/index.js";
 import { invalidatePluginPermissionCache } from "../../plugins/permissions.js";
+import {
+  findField,
+  getAllSettings,
+  setSetting,
+  type PluginSettingsScope,
+} from "../../plugins/settings.js";
+import {
+  getAuditUsername,
+  getRequestMeta,
+  logAudit,
+} from "../../utils/audit-logger.js";
+import type {
+  PluginManifest,
+  PluginSettingsField,
+} from "@termix/plugin-sdk/manifest";
 
 const router = express.Router();
 
+/** A settings body is a flat object; an array or null is a client bug. */
+function isPlainBody(body: unknown): body is Record<string, unknown> {
+  return typeof body === "object" && body !== null && !Array.isArray(body);
+}
+
 const authManager = AuthManager.getInstance();
 const authenticateJWT = authManager.createAuthMiddleware();
 const permissionManager = PermissionManager.getInstance();
@@ -79,15 +99,18 @@ router.get("/", authenticateJWT, async (req: Request, res: Response) => {
 
       let contributes: unknown = null;
       let capabilities: string[] = [];
+      let icon: string | undefined;
       try {
         const manifest = JSON.parse(record.manifestJson) as {
           contributes?: unknown;
           capabilities?: unknown;
+          icon?: unknown;
         };
         contributes = manifest?.contributes ?? null;
         capabilities = Array.isArray(manifest?.capabilities)
           ? (manifest.capabilities as string[])
           : [];
+        icon = typeof manifest?.icon === "string" ? manifest.icon : undefined;
       } catch {
         contributes = null;
       }
@@ -99,6 +122,7 @@ router.get("/", authenticateJWT, async (req: Request, res: Response) => {
         enabled: record.state === "enabled",
         state: loaded?.state ?? record.state,
         contributes,
+        icon,
       };
 
       if (!canManage) return summary;
@@ -528,4 +552,535 @@ router.delete(
   },
 );
 
+/**
+ * Loads a plugin's manifest for the settings routes.
+ *
+ * Read from the loader rather than the database row so the fields a request is
+ * validated against are the ones the running build declares.
+ */
+async function loadManifestForSettings(
+  pluginId: string,
+): Promise<PluginManifest | null> {
+  const { loader } = getPluginRuntime();
+  const live = loader.get(pluginId);
+  if (live?.manifest) return live.manifest;
+
+  const record = await createCurrentPluginRepository().findById(pluginId);
+  if (!record) return null;
+  try {
+    return JSON.parse(record.manifestJson) as PluginManifest;
+  } catch {
+    return null;
+  }
+}
+
+/**
+ * Whether the caller may write a given field.
+ *
+ * Admin fields fall back to admin.plugins.manage, so a plugin that declares no
+ * permission of its own still cannot have its install-wide settings changed by
+ * an ordinary user. A field naming its own permission uses that instead.
+ */
+async function canWriteField(
+  userId: string,
+  manifest: PluginManifest,
+  scope: PluginSettingsScope,
+  field: PluginSettingsField,
+): Promise<boolean> {
+  // Admin scope always needs admin.plugins.manage. A field-level permission
+  // narrows who may write it; it never widens the scope's own gate, so a
+  // plugin cannot hand an ordinary user install-wide configuration by naming
+  // a permission that user happens to hold.
+  if (
+    scope === "admin" &&
+    !(await permissionManager.hasPermission(userId, "admin.plugins.manage"))
+  ) {
+    return false;
+  }
+
+  if (field.permission) {
+    const { resolvePermission } = await import("../../plugins/rbac.js");
+    return permissionManager.hasPermission(
+      userId,
+      resolvePermission(manifest, field.permission),
+    );
+  }
+
+  return true;
+}
+
+/** Applies a body of values to one scope, collecting per-field errors. */
+async function applySettings(
+  userId: string,
+  manifest: PluginManifest,
+  scope: PluginSettingsScope,
+  scopeId: string | null,
+  body: Record<string, unknown>,
+): Promise<Record<string, string>> {
+  const errors: Record<string, string> = {};
+
+  for (const [key, value] of Object.entries(body)) {
+    const field = findField(manifest, scope, key);
+    if (!field) {
+      errors[key] = "Not a settings field this plugin declares";
+      continue;
+    }
+    if (!(await canWriteField(userId, manifest, scope, field))) {
+      errors[key] = "You do not have permission to change this setting";
+      continue;
+    }
+
+    const error = await setSetting(manifest, scope, scopeId, key, value);
+    if (error) errors[key] = error;
+  }
+
+  return errors;
+}
+
+/**
+ * @openapi
+ * /plugins/{id}/settings/admin:
+ *   get:
+ *     summary: Read a plugin's install-wide settings
+ *     description: >
+ *       Returns every admin-scope field the plugin declares, with stored values
+ *       over declared defaults. Secret fields come back as { set: boolean } and
+ *       never carry their value, so a browser can render "configured" without
+ *       ever holding the secret.
+ *     tags:
+ *       - Plugins
+ *     parameters:
+ *       - in: path
+ *         name: id
+ *         required: true
+ *         schema:
+ *           type: string
+ *     responses:
+ *       200:
+ *         description: The plugin's admin settings.
+ *       403:
+ *         description: The caller lacks admin.plugins.manage.
+ *       404:
+ *         description: No such plugin.
+ */
+router.get(
+  "/:id/settings/admin",
+  authenticateJWT,
+  requireManagePlugins,
+  async (req: Request, res: Response) => {
+    const pluginId = String(req.params.id);
+    try {
+      const manifest = await loadManifestForSettings(pluginId);
+      if (!manifest) {
+        res.status(404).json({ error: "No such plugin" });
+        return;
+      }
+      const values = await getAllSettings(manifest, "admin", null, {
+        redactSecrets: true,
+      });
+      res.json({ id: pluginId, values });
+    } catch (error) {
+      databaseLogger.error(
+        `Failed to read admin settings for plugin ${pluginId}`,
+        error instanceof Error ? error : new Error(String(error)),
+        { operation: "plugin_settings_read" },
+      );
+      res.status(500).json({ error: "Failed to read the plugin's settings" });
+    }
+  },
+);
+
+/**
+ * @openapi
+ * /plugins/{id}/settings/admin:
+ *   put:
+ *     summary: Update a plugin's install-wide settings
+ *     description: >
+ *       Writes the given keys. Every value is validated against the field the
+ *       manifest declares, and a key the manifest never declared is rejected
+ *       rather than stored. Validation failures come back per field so a form
+ *       can show every problem at once. Sending a secret field back as
+ *       { set: true } leaves the stored value alone, so saving a form does not
+ *       clear a key it was never shown.
+ *     tags:
+ *       - Plugins
+ *     parameters:
+ *       - in: path
+ *         name: id
+ *         required: true
+ *         schema:
+ *           type: string
+ *     requestBody:
+ *       required: true
+ *       content:
+ *         application/json:
+ *           schema:
+ *             type: object
+ *     responses:
+ *       200:
+ *         description: The updated settings.
+ *       400:
+ *         description: One or more fields were rejected.
+ *       403:
+ *         description: The caller lacks admin.plugins.manage.
+ *       404:
+ *         description: No such plugin.
+ */
+router.put(
+  "/:id/settings/admin",
+  authenticateJWT,
+  requireManagePlugins,
+  async (req: Request, res: Response) => {
+    const pluginId = String(req.params.id);
+    const userId = (req as AuthenticatedRequest).userId as string;
+
+    if (!isPlainBody(req.body)) {
+      res.status(400).json({ error: "Body must be an object of settings" });
+      return;
+    }
+
+    try {
+      const manifest = await loadManifestForSettings(pluginId);
+      if (!manifest) {
+        res.status(404).json({ error: "No such plugin" });
+        return;
+      }
+
+      const errors = await applySettings(
+        userId,
+        manifest,
+        "admin",
+        null,
+        req.body,
+      );
+      if (Object.keys(errors).length > 0) {
+        res.status(400).json({ error: "Some settings were rejected", errors });
+        return;
+      }
+
+      const { ipAddress, userAgent } = getRequestMeta(req);
+      await logAudit({
+        userId,
+        username: await getAuditUsername(userId),
+        action: "update_plugin_settings",
+        resourceType: "setting",
+        resourceId: pluginId,
+        resourceName: manifest.name,
+        // Keys only: a value here could be the secret we just encrypted.
+        details: JSON.stringify({
+          scope: "admin",
+          keys: Object.keys(req.body),
+        }),
+        ipAddress,
+        userAgent,
+        success: true,
+      });
+
+      const values = await getAllSettings(manifest, "admin", null, {
+        redactSecrets: true,
+      });
+      res.json({ id: pluginId, values });
+    } catch (error) {
+      databaseLogger.error(
+        `Failed to update admin settings for plugin ${pluginId}`,
+        error instanceof Error ? error : new Error(String(error)),
+        { operation: "plugin_settings_write" },
+      );
+      res.status(500).json({ error: "Failed to update the plugin's settings" });
+    }
+  },
+);
+
+/**
+ * @openapi
+ * /plugins/{id}/settings/user:
+ *   get:
+ *     summary: Read the caller's own settings for a plugin
+ *     description: Returns every user-scope field the plugin declares for the authenticated user. The scope is always the caller, never a user id from the request.
+ *     tags:
+ *       - Plugins
+ *     parameters:
+ *       - in: path
+ *         name: id
+ *         required: true
+ *         schema:
+ *           type: string
+ *     responses:
+ *       200:
+ *         description: The caller's settings for this plugin.
+ *       404:
+ *         description: No such plugin.
+ */
+router.get(
+  "/:id/settings/user",
+  authenticateJWT,
+  async (req: Request, res: Response) => {
+    const pluginId = String(req.params.id);
+    const userId = (req as AuthenticatedRequest).userId as string;
+
+    try {
+      const manifest = await loadManifestForSettings(pluginId);
+      if (!manifest) {
+        res.status(404).json({ error: "No such plugin" });
+        return;
+      }
+      const values = await getAllSettings(manifest, "user", userId, {
+        redactSecrets: true,
+      });
+      res.json({ id: pluginId, values });
+    } catch (error) {
+      databaseLogger.error(
+        `Failed to read user settings for plugin ${pluginId}`,
+        error instanceof Error ? error : new Error(String(error)),
+        { operation: "plugin_settings_read" },
+      );
+      res.status(500).json({ error: "Failed to read the plugin's settings" });
+    }
+  },
+);
+
+/**
+ * @openapi
+ * /plugins/{id}/settings/user:
+ *   put:
+ *     summary: Update the caller's own settings for a plugin
+ *     description: Writes user-scope values for the authenticated user. The scope is always the caller, so one user can never write another's settings.
+ *     tags:
+ *       - Plugins
+ *     parameters:
+ *       - in: path
+ *         name: id
+ *         required: true
+ *         schema:
+ *           type: string
+ *     requestBody:
+ *       required: true
+ *       content:
+ *         application/json:
+ *           schema:
+ *             type: object
+ *     responses:
+ *       200:
+ *         description: The updated settings.
+ *       400:
+ *         description: One or more fields were rejected.
+ *       404:
+ *         description: No such plugin.
+ */
+router.put(
+  "/:id/settings/user",
+  authenticateJWT,
+  async (req: Request, res: Response) => {
+    const pluginId = String(req.params.id);
+    const userId = (req as AuthenticatedRequest).userId as string;
+
+    if (!isPlainBody(req.body)) {
+      res.status(400).json({ error: "Body must be an object of settings" });
+      return;
+    }
+
+    try {
+      const manifest = await loadManifestForSettings(pluginId);
+      if (!manifest) {
+        res.status(404).json({ error: "No such plugin" });
+        return;
+      }
+
+      const errors = await applySettings(
+        userId,
+        manifest,
+        "user",
+        userId,
+        req.body,
+      );
+      if (Object.keys(errors).length > 0) {
+        res.status(400).json({ error: "Some settings were rejected", errors });
+        return;
+      }
+
+      const values = await getAllSettings(manifest, "user", userId, {
+        redactSecrets: true,
+      });
+      res.json({ id: pluginId, values });
+    } catch (error) {
+      databaseLogger.error(
+        `Failed to update user settings for plugin ${pluginId}`,
+        error instanceof Error ? error : new Error(String(error)),
+        { operation: "plugin_settings_write" },
+      );
+      res.status(500).json({ error: "Failed to update the plugin's settings" });
+    }
+  },
+);
+
+/**
+ * @openapi
+ * /plugins/{id}/settings/host/{hostId}:
+ *   get:
+ *     summary: Read a plugin's settings for one host
+ *     description: Returns every host-scope field the plugin declares for that host. Requires edit access to the host, the same check the host editor itself uses.
+ *     tags:
+ *       - Plugins
+ *     parameters:
+ *       - in: path
+ *         name: id
+ *         required: true
+ *         schema:
+ *           type: string
+ *       - in: path
+ *         name: hostId
+ *         required: true
+ *         schema:
+ *           type: integer
+ *     responses:
+ *       200:
+ *         description: The plugin's settings for that host.
+ *       400:
+ *         description: Invalid host id.
+ *       403:
+ *         description: No edit access to that host.
+ *       404:
+ *         description: No such plugin.
+ */
+router.get(
+  "/:id/settings/host/:hostId",
+  authenticateJWT,
+  async (req: Request, res: Response) => {
+    const pluginId = String(req.params.id);
+    const userId = (req as AuthenticatedRequest).userId as string;
+    const hostId = Number(req.params.hostId);
+
+    if (!Number.isInteger(hostId) || hostId <= 0) {
+      res.status(400).json({ error: "Invalid host ID" });
+      return;
+    }
+
+    try {
+      const manifest = await loadManifestForSettings(pluginId);
+      if (!manifest) {
+        res.status(404).json({ error: "No such plugin" });
+        return;
+      }
+
+      const access = await permissionManager.canAccessHost(
+        userId,
+        hostId,
+        "edit",
+      );
+      if (!access.hasAccess) {
+        res.status(403).json({ error: "Access denied to host" });
+        return;
+      }
+
+      const values = await getAllSettings(manifest, "host", hostId, {
+        redactSecrets: true,
+      });
+      res.json({ id: pluginId, hostId, values });
+    } catch (error) {
+      databaseLogger.error(
+        `Failed to read host settings for plugin ${pluginId}`,
+        error instanceof Error ? error : new Error(String(error)),
+        { operation: "plugin_settings_read" },
+      );
+      res.status(500).json({ error: "Failed to read the plugin's settings" });
+    }
+  },
+);
+
+/**
+ * @openapi
+ * /plugins/{id}/settings/host/{hostId}:
+ *   put:
+ *     summary: Update a plugin's settings for one host
+ *     description: Writes host-scope values. Requires edit access to the host, so a user who may only connect to a shared host cannot change how a plugin treats it.
+ *     tags:
+ *       - Plugins
+ *     parameters:
+ *       - in: path
+ *         name: id
+ *         required: true
+ *         schema:
+ *           type: string
+ *       - in: path
+ *         name: hostId
+ *         required: true
+ *         schema:
+ *           type: integer
+ *     requestBody:
+ *       required: true
+ *       content:
+ *         application/json:
+ *           schema:
+ *             type: object
+ *     responses:
+ *       200:
+ *         description: The updated settings.
+ *       400:
+ *         description: Invalid host id, or one or more fields were rejected.
+ *       403:
+ *         description: No edit access to that host.
+ *       404:
+ *         description: No such plugin.
+ */
+router.put(
+  "/:id/settings/host/:hostId",
+  authenticateJWT,
+  async (req: Request, res: Response) => {
+    const pluginId = String(req.params.id);
+    const userId = (req as AuthenticatedRequest).userId as string;
+    const hostId = Number(req.params.hostId);
+
+    if (!Number.isInteger(hostId) || hostId <= 0) {
+      res.status(400).json({ error: "Invalid host ID" });
+      return;
+    }
+    if (!isPlainBody(req.body)) {
+      res.status(400).json({ error: "Body must be an object of settings" });
+      return;
+    }
+
+    try {
+      const manifest = await loadManifestForSettings(pluginId);
+      if (!manifest) {
+        res.status(404).json({ error: "No such plugin" });
+        return;
+      }
+
+      const access = await permissionManager.canAccessHost(
+        userId,
+        hostId,
+        "edit",
+      );
+      if (!access.hasAccess) {
+        res.status(403).json({ error: "Access denied to host" });
+        return;
+      }
+
+      const errors = await applySettings(
+        userId,
+        manifest,
+        "host",
+        String(hostId),
+        req.body,
+      );
+      if (Object.keys(errors).length > 0) {
+        res.status(400).json({ error: "Some settings were rejected", errors });
+        return;
+      }
+
+      const values = await getAllSettings(manifest, "host", hostId, {
+        redactSecrets: true,
+      });
+      res.json({ id: pluginId, hostId, values });
+    } catch (error) {
+      databaseLogger.error(
+        `Failed to update host settings for plugin ${pluginId}`,
+        error instanceof Error ? error : new Error(String(error)),
+        { operation: "plugin_settings_write" },
+      );
+      res.status(500).json({ error: "Failed to update the plugin's settings" });
+    }
+  },
+);
+
 export default router;

src/backend/database/routes/user-settings-routes.ts

@@ -338,120 +338,6 @@ export function registerUserSettingsRoutes(
     }
   });
 
-  /**
-   * @openapi
-   * /users/tailscale-settings:
-   *   get:
-   *     summary: Get Tailscale settings
-   *     description: Returns whether a Tailscale API key is configured (value is masked).
-   *     tags:
-   *       - Users
-   *     responses:
-   *       200:
-   *         description: Tailscale settings.
-   *         content:
-   *           application/json:
-   *             schema:
-   *               type: object
-   *               properties:
-   *                 apiKey:
-   *                   type: string
-   *                   description: Masked API key or empty string if not set.
-   *                 hasApiKey:
-   *                   type: boolean
-   *                 apiBaseUrl:
-   *                   type: string
-   *                   description: Custom control-plane API base URL (e.g. a Headscale instance), or empty string for the Tailscale default.
-   */
-  router.get("/tailscale-settings", authenticateJWT, async (_req, res) => {
-    try {
-      const settingsRepo = createCurrentSettingsRepository();
-      const apiKey = (await settingsRepo.get("tailscale_api_key")) ?? "";
-      const apiBaseUrl =
-        (await settingsRepo.get("tailscale_api_base_url")) ?? "";
-      res.json({
-        apiKey: apiKey
-          ? `${apiKey.slice(0, 6)}${"*".repeat(Math.max(0, apiKey.length - 6))}`
-          : "",
-        hasApiKey: !!apiKey,
-        apiBaseUrl,
-      });
-    } catch (err) {
-      authLogger.error("Failed to get Tailscale settings", err);
-      res.status(500).json({ error: "Failed to get Tailscale settings" });
-    }
-  });
-
-  /**
-   * @openapi
-   * /users/tailscale-settings:
-   *   patch:
-   *     summary: Update Tailscale settings (admin only)
-   *     description: Saves or clears the Tailscale API key used for device discovery.
-   *     tags:
-   *       - Users
-   *     requestBody:
-   *       required: true
-   *       content:
-   *         application/json:
-   *           schema:
-   *             type: object
-   *             properties:
-   *               apiKey:
-   *                 type: string
-   *               apiBaseUrl:
-   *                 type: string
-   *                 description: Optional custom control-plane API base URL (e.g. a Headscale instance). Leave empty to use the Tailscale default.
-   *     responses:
-   *       200:
-   *         description: Tailscale settings updated.
-   *       403:
-   *         description: Not authorized.
-   *       500:
-   *         description: Failed to update Tailscale settings.
-   */
-  router.patch("/tailscale-settings", authenticateJWT, async (req, res) => {
-    const userId = (req as AuthenticatedRequest).userId;
-    try {
-      const actor = await getAdminActor(userId);
-      if (!actor) {
-        return res.status(403).json({ error: "Not authorized" });
-      }
-      const { apiKey, apiBaseUrl } = req.body;
-      if (typeof apiKey !== "string") {
-        return res.status(400).json({ error: "apiKey must be a string" });
-      }
-      if (apiBaseUrl !== undefined && typeof apiBaseUrl !== "string") {
-        return res.status(400).json({ error: "apiBaseUrl must be a string" });
-      }
-      const settingsRepo = createCurrentSettingsRepository();
-      await settingsRepo.set("tailscale_api_key", apiKey);
-      if (apiBaseUrl !== undefined) {
-        await settingsRepo.set(
-          "tailscale_api_base_url",
-          apiBaseUrl.trim().replace(/\/+$/, ""),
-        );
-      }
-
-      const { ipAddress, userAgent } = getRequestMeta(req);
-      await logAudit({
-        userId,
-        username: actor.username ?? userId,
-        action: "update_tailscale_settings",
-        resourceType: "setting",
-        details: JSON.stringify({ hasApiKey: !!apiKey }),
-        ipAddress,
-        userAgent,
-        success: true,
-      });
-
-      res.json({ hasApiKey: !!apiKey });
-    } catch (err) {
-      authLogger.error("Failed to update Tailscale settings", err);
-      res.status(500).json({ error: "Failed to update Tailscale settings" });
-    }
-  });
-
   /**
    * @openapi
    * /users/command-history-enabled:

src/backend/plugins/ctx.ts

@@ -36,6 +36,7 @@ import {
 } from "./http.js";
 import { registerPluginWsRoute, registerPluginWsUpgrade } from "./ws.js";
 import { resolvePermission } from "./rbac.js";
+import * as pluginSettings from "./settings.js";
 import type { PluginManifest } from "@termix/plugin-sdk/manifest";
 import {
   PluginCapabilityError,
@@ -257,6 +258,18 @@ export function createPluginContext(
     { action: "db_client" },
   );
 
+  // The one settings call that leaves the plugin's own namespace, so the one
+  // that needs a capability and an audit line.
+  const settingsReadCore = guarded(
+    manifest,
+    "settings:read-core",
+    async (key: string) => pluginSettings.readCoreSetting(key),
+    {
+      action: "settings_read_core",
+      details: () => "read a core server setting",
+    },
+  );
+
   const dbRefs = guarded(
     manifest,
     "db:own",
@@ -474,6 +487,66 @@ export function createPluginContext(
       },
     },
 
+    settings: {
+      // Reading and writing a plugin's OWN settings is ungated. The manifest
+      // already declares every field, and a plugin that had to ask permission
+      // to read its own configuration would be useless. Only readCore, which
+      // reaches outside the plugin's namespace, is a capability.
+      get: (key) =>
+        pluginSettings.getSetting(manifest, "admin", null, key) as never,
+      set: async (key, value) => {
+        const error = await pluginSettings.setSetting(
+          manifest,
+          "admin",
+          null,
+          key,
+          value,
+        );
+        if (error) throw new Error(error);
+      },
+
+      getUser: (userId, key) =>
+        pluginSettings.getSetting(manifest, "user", userId, key) as never,
+      setUser: async (userId, key, value) => {
+        const error = await pluginSettings.setSetting(
+          manifest,
+          "user",
+          userId,
+          key,
+          value,
+        );
+        if (error) throw new Error(error);
+      },
+
+      getHost: (hostId, key) =>
+        pluginSettings.getSetting(manifest, "host", hostId, key) as never,
+      setHost: async (hostId, key, value) => {
+        const error = await pluginSettings.setSetting(
+          manifest,
+          "host",
+          hostId,
+          key,
+          value,
+        );
+        if (error) throw new Error(error);
+      },
+
+      getAll: (scope, scopeId) =>
+        pluginSettings.getAllSettings(manifest, scope, scopeId ?? null),
+
+      onChange: (key, listener) => {
+        const unsubscribe = pluginSettings.onSettingsChange(
+          pluginId,
+          key,
+          listener,
+        );
+        handle.bag.add(unsubscribe, `settings listener for "${key}"`);
+        return unsubscribe;
+      },
+
+      readCore: (key) => settingsReadCore(key),
+    },
+
     rbac: {
       // A short name takes this plugin's prefix; another plugin's id or a core
       // group is used as given, which is what makes a cross-plugin check
@@ -623,6 +696,7 @@ export async function disposePluginHandle(
   // Belt and braces: an offer made outside ctx, or one whose registration was
   // lost to a throw mid-activate, would otherwise outlive the plugin.
   secretRegistry.withdrawAllForPlugin(pluginId);
+  pluginSettings.clearSettingsListeners(pluginId);
 
   // Skipped when activate() never finished: a plugin's deactivate expects the
   // state activate builds, and calling it on a half-built plugin tends to

src/backend/plugins/settings.ts

@@ -0,0 +1,319 @@
+/**
+ * Plugin settings: validation, storage, encryption and change notification.
+ *
+ * One module behind both ctx.settings and the /plugins/:id/settings routes, so
+ * "what is a valid value", "which fields are secret" and "what a read hands
+ * back" are decided once. Two implementations would drift, and the one that
+ * drifted would be the one writing to the database.
+ *
+ * A field the manifest never declared is rejected rather than stored. That is
+ * what stops a PUT from filling a plugin's namespace with arbitrary keys, and
+ * it is why every entry point resolves the field first and the value second.
+ */
+
+import type {
+  PluginManifest,
+  PluginSettingsField,
+} from "@termix/plugin-sdk/manifest";
+import {
+  coerceSettingValue,
+  isRedactedSecret,
+  validateSettingValue,
+} from "@termix/plugin-sdk/settings";
+import { createCurrentPluginSettingsRepository } from "../database/repositories/factory.js";
+import type { PluginSettingsScope } from "../database/repositories/plugin-settings-repository.js";
+import {
+  decryptSystemSecret,
+  encryptSystemSecret,
+} from "../utils/system-secret-crypto.js";
+import { pluginLogger } from "../utils/logger.js";
+
+export type { PluginSettingsScope };
+
+/**
+ * Core settings a plugin may read through ctx.settings.readCore.
+ *
+ * Deliberately short. Everything here is either already visible in the UI to
+ * every user, or a switch a plugin has to honour to behave correctly. Adding
+ * to it means deciding that every plugin holding settings:read-core may see
+ * that value, so it is a review decision rather than a convenience.
+ */
+export const CORE_SETTINGS_ALLOWLIST: readonly string[] = [
+  "app_name",
+  "guac_enabled",
+  "global_metrics_interval",
+  "global_status_check_interval",
+];
+
+type ChangeListener = (value: unknown) => void;
+
+/** pluginId -> key -> listeners. In-process only; settings are not clustered. */
+const listeners = new Map<string, Map<string, Set<ChangeListener>>>();
+
+export function onSettingsChange(
+  pluginId: string,
+  key: string,
+  listener: ChangeListener,
+): () => void {
+  let byKey = listeners.get(pluginId);
+  if (!byKey) {
+    byKey = new Map();
+    listeners.set(pluginId, byKey);
+  }
+  let set = byKey.get(key);
+  if (!set) {
+    set = new Set();
+    byKey.set(key, set);
+  }
+  set.add(listener);
+
+  return () => {
+    set!.delete(listener);
+    if (set!.size === 0) byKey!.delete(key);
+    if (byKey!.size === 0) listeners.delete(pluginId);
+  };
+}
+
+function notify(pluginId: string, key: string, value: unknown): void {
+  for (const listener of listeners.get(pluginId)?.get(key) ?? []) {
+    try {
+      listener(value);
+    } catch (error) {
+      // A listener throwing must not fail the write that already happened.
+      pluginLogger.error(
+        `Plugin ${pluginId} settings listener for "${key}" failed`,
+        error instanceof Error ? error : new Error(String(error)),
+        { operation: "plugin_settings_change" },
+      );
+    }
+  }
+}
+
+/** Drops every listener a plugin registered. Called when it deactivates. */
+export function clearSettingsListeners(pluginId: string): void {
+  listeners.delete(pluginId);
+}
+
+/** The fields a manifest declares for one scope. */
+export function declaredFields(
+  manifest: PluginManifest,
+  scope: PluginSettingsScope,
+): PluginSettingsField[] {
+  const settings = manifest.contributes?.settings;
+  if (!settings) return [];
+
+  if (scope === "admin") return settings.admin ?? [];
+  if (scope === "user") return settings.user ?? [];
+
+  const host = settings.host;
+  if (!host) return [];
+
+  // The enable switch is a real stored key, so it has to behave like a field
+  // everywhere: validated on write, defaulted on read, rendered in the editor.
+  const enableField: PluginSettingsField[] = host.enableKey
+    ? [
+        {
+          key: host.enableKey,
+          type: "boolean",
+          labelKey: host.enableLabelKey,
+          default: false,
+        },
+      ]
+    : [];
+
+  return [...enableField, ...host.fields];
+}
+
+export function findField(
+  manifest: PluginManifest,
+  scope: PluginSettingsScope,
+  key: string,
+): PluginSettingsField | undefined {
+  return declaredFields(manifest, scope).find((field) => field.key === key);
+}
+
+function normalizeScopeId(
+  scope: PluginSettingsScope,
+  scopeId: string | number | undefined | null,
+): string | null {
+  if (scope === "admin") return null;
+  if (scopeId === undefined || scopeId === null) {
+    throw new Error(`Plugin settings scope "${scope}" requires a scope id`);
+  }
+  return String(scopeId);
+}
+
+/** Stored values are JSON so a field keeps its declared type on the way back. */
+function encode(value: unknown): string {
+  return JSON.stringify(value ?? null);
+}
+
+function decode(raw: string | null): unknown {
+  if (raw === null) return undefined;
+  try {
+    return JSON.parse(raw);
+  } catch {
+    return undefined;
+  }
+}
+
+export async function getSetting(
+  manifest: PluginManifest,
+  scope: PluginSettingsScope,
+  scopeId: string | number | null | undefined,
+  key: string,
+): Promise<unknown> {
+  const field = findField(manifest, scope, key);
+  if (!field) return undefined;
+
+  const row = await createCurrentPluginSettingsRepository().get(
+    manifest.id,
+    scope,
+    normalizeScopeId(scope, scopeId),
+    key,
+  );
+
+  if (!row || row.value === null) return field.default;
+
+  const decoded = decode(row.value);
+  if (decoded === undefined || decoded === null) return field.default;
+
+  if (row.encrypted && typeof decoded === "string") {
+    return decryptSystemSecret(decoded);
+  }
+  return decoded;
+}
+
+export interface SetSettingOptions {
+  /** Skips validation for a value core itself produced, such as a migration. */
+  trusted?: boolean;
+}
+
+/**
+ * Writes one value, after validating it against the declared field.
+ *
+ * Returns the error message when the value is rejected, or null on success,
+ * rather than throwing: a PUT reports every bad field at once and a throw per
+ * field would only ever surface the first.
+ */
+export async function setSetting(
+  manifest: PluginManifest,
+  scope: PluginSettingsScope,
+  scopeId: string | number | null | undefined,
+  key: string,
+  value: unknown,
+  options: SetSettingOptions = {},
+): Promise<string | null> {
+  const field = findField(manifest, scope, key);
+  if (!field) {
+    return `"${key}" is not a settings field this plugin declares`;
+  }
+
+  // Echoing a redacted secret back means "leave it alone", so a form can save
+  // without clearing a key it was never shown.
+  if (field.type === "secret" && isRedactedSecret(value)) return null;
+
+  const coerced = options.trusted ? value : coerceSettingValue(field, value);
+  if (!options.trusted) {
+    const error = validateSettingValue(field, coerced);
+    if (error) return error;
+  }
+
+  // Clearing a secret writes null rather than an encrypted empty string, so a
+  // read reports it as unset instead of "set to nothing".
+  const clearingSecret = field.type === "secret" && coerced === "";
+  const shouldEncrypt =
+    field.type === "secret" && typeof coerced === "string" && !clearingSecret;
+  const stored = clearingSecret
+    ? null
+    : shouldEncrypt
+      ? encode(await encryptSystemSecret(coerced as string))
+      : encode(coerced);
+
+  await createCurrentPluginSettingsRepository().set(
+    manifest.id,
+    scope,
+    normalizeScopeId(scope, scopeId),
+    key,
+    stored,
+    shouldEncrypt,
+  );
+
+  notify(manifest.id, key, coerced);
+  return null;
+}
+
+export interface GetAllOptions {
+  /** Replaces every secret with { set } so the value never leaves the server. */
+  redactSecrets?: boolean;
+}
+
+/**
+ * Every declared field for one scope, with stored values over defaults.
+ *
+ * Driven by the manifest rather than by the rows, so a field that was never
+ * written still comes back with its default and a stale row for a field the
+ * plugin has since dropped is ignored instead of being handed to the UI.
+ */
+export async function getAllSettings(
+  manifest: PluginManifest,
+  scope: PluginSettingsScope,
+  scopeId: string | number | null | undefined,
+  options: GetAllOptions = {},
+): Promise<Record<string, unknown>> {
+  const fields = declaredFields(manifest, scope);
+  if (fields.length === 0) return {};
+
+  const rows = await createCurrentPluginSettingsRepository().getAll(
+    manifest.id,
+    scope,
+    normalizeScopeId(scope, scopeId),
+  );
+  const byKey = new Map(rows.map((row) => [row.key, row]));
+
+  const values: Record<string, unknown> = {};
+  for (const field of fields) {
+    values[field.key] = await resolveFieldValue(
+      field,
+      byKey.get(field.key),
+      options,
+    );
+  }
+  return values;
+}
+
+/** Shared by getAllSettings and the host-list projection. */
+export async function resolveFieldValue(
+  field: PluginSettingsField,
+  row: { value: string | null; encrypted: boolean } | undefined,
+  options: GetAllOptions = {},
+): Promise<unknown> {
+  const decoded = row && row.value !== null ? decode(row.value) : undefined;
+  const hasValue = decoded !== undefined && decoded !== null && decoded !== "";
+
+  if (field.type === "secret") {
+    if (options.redactSecrets) return { set: hasValue };
+    if (!hasValue) return field.default;
+    return row!.encrypted && typeof decoded === "string"
+      ? decryptSystemSecret(decoded)
+      : decoded;
+  }
+
+  return hasValue ? decoded : field.default;
+}
+
+/**
+ * Reads a core server setting. The caller has already checked
+ * settings:read-core; this only enforces the allowlist.
+ */
+export async function readCoreSetting(key: string): Promise<string | null> {
+  if (!CORE_SETTINGS_ALLOWLIST.includes(key)) {
+    throw new Error(
+      `Core setting "${key}" is not readable by plugins. Readable keys: ${CORE_SETTINGS_ALLOWLIST.join(", ")}`,
+    );
+  }
+
+  const { createCurrentSettingsRepository } =
+    await import("../database/repositories/factory.js");
+  return createCurrentSettingsRepository().get(key);
+}

src/backend/starter.ts

@@ -344,6 +344,12 @@ async function provisionLocalDesktopUserIfNeeded(): Promise<void> {
           operation: "plugin_init",
         });
       }
+
+      // After seeding: plugin_settings has a foreign key to plugins, so there
+      // is nothing to migrate into until the plugin row exists.
+      const { runTailscaleSettingsMigration } =
+        await import("./utils/crypto-migration/tailscale-settings-migration.js");
+      await runTailscaleSettingsMigration();
     } catch (error) {
       systemLogger.warn("Plugin runtime failed to initialize", {
         operation: "plugin_init",

src/backend/tests/database/plugin-settings-cascade.test.ts

@@ -0,0 +1,147 @@
+/**
+ * plugin_settings cleanup when a user or host goes.
+ *
+ * scope_id is polymorphic, so it carries no foreign key and the engine will
+ * not cascade it. The repositories delete these rows explicitly, and these
+ * tests exist so a later refactor that drops those calls fails here rather
+ * than leaving orphaned settings behind forever.
+ */
+
+import { asc } from "drizzle-orm";
+import { afterEach, describe, expect, it } from "vitest";
+import { TestSqliteDatabase } from "./repositories/test-support.js";
+import { HostRepository } from "../../database/repositories/host-repository.js";
+import { UserRepository } from "../../database/repositories/user-repository.js";
+import type { DatabaseContext } from "../../database/repositories/database-context.js";
+import { pluginSettings } from "../../database/db/schema.js";
+
+let adapter: TestSqliteDatabase | null = null;
+let ctx: DatabaseContext | null = null;
+
+afterEach(async () => {
+  if (adapter) {
+    await adapter.close();
+    adapter = null;
+    ctx = null;
+  }
+});
+
+async function seed(): Promise<DatabaseContext> {
+  adapter = new TestSqliteDatabase();
+  const context = await adapter.connect();
+  ctx = context;
+
+  await adapter.exec(`
+    INSERT INTO users (id, username, password_hash)
+    VALUES ('user-1', 'alice', 'hash'), ('user-2', 'bob', 'hash');
+
+    INSERT INTO ssh_data (id, user_id, name, ip, port, username, auth_type)
+    VALUES
+      (7, 'user-1', 'seven', '10.0.0.7', 22, 'root', 'password'),
+      (8, 'user-1', 'eight', '10.0.0.8', 22, 'root', 'password'),
+      (9, 'user-2', 'nine', '10.0.0.9', 22, 'root', 'password');
+
+    INSERT INTO plugins (id, name, version, manifest_json)
+    VALUES ('sample', 'Sample', '1.0.0', '{}');
+  `);
+
+  return context;
+}
+
+async function addSetting(
+  scope: string,
+  scopeId: string | null,
+  key = "k",
+): Promise<void> {
+  await adapter!.exec(
+    `INSERT INTO plugin_settings (plugin_id, scope, scope_id, key, value)
+     VALUES ('sample', '${scope}', ${scopeId === null ? "NULL" : `'${scopeId}'`}, '${key}', '"v"')`,
+  );
+}
+
+async function remaining(): Promise<
+  { scope: string; scopeId: string | null }[]
+> {
+  const rows = await ctx!.drizzle
+    .select({
+      scope: pluginSettings.scope,
+      scopeId: pluginSettings.scopeId,
+    })
+    .from(pluginSettings)
+    .orderBy(asc(pluginSettings.scope), asc(pluginSettings.scopeId));
+  return rows;
+}
+
+describe("user deletion", () => {
+  it("removes that user's plugin settings", async () => {
+    const context = await seed();
+    await addSetting("user", "user-1");
+
+    await new UserRepository(context).delete("user-1");
+
+    expect(await remaining()).toEqual([]);
+  });
+
+  it("leaves another user's settings alone", async () => {
+    const context = await seed();
+    await addSetting("user", "user-1");
+    await addSetting("user", "user-2");
+
+    await new UserRepository(context).delete("user-1");
+
+    expect(await remaining()).toEqual([{ scope: "user", scopeId: "user-2" }]);
+  });
+
+  it("leaves admin-scope settings alone", async () => {
+    const context = await seed();
+    await addSetting("admin", null);
+    await addSetting("user", "user-1");
+
+    await new UserRepository(context).delete("user-1");
+
+    expect(await remaining()).toEqual([{ scope: "admin", scopeId: null }]);
+  });
+});
+
+describe("host deletion", () => {
+  it("removes that host's plugin settings", async () => {
+    const context = await seed();
+    await addSetting("host", "7");
+
+    await new HostRepository(context).deleteForUser("user-1", 7);
+
+    expect(await remaining()).toEqual([]);
+  });
+
+  it("leaves another host's settings alone", async () => {
+    const context = await seed();
+    await addSetting("host", "7");
+    await addSetting("host", "8");
+
+    await new HostRepository(context).deleteForUser("user-1", 7);
+
+    expect(await remaining()).toEqual([{ scope: "host", scopeId: "8" }]);
+  });
+
+  it("clears settings for every host in the bulk delete path", async () => {
+    const context = await seed();
+    await addSetting("host", "7");
+    await addSetting("host", "8");
+    await addSetting("host", "9");
+
+    await new HostRepository(context).deleteByUserId("user-1");
+
+    // Host 9 belongs to another user and keeps its settings.
+    expect(await remaining()).toEqual([{ scope: "host", scopeId: "9" }]);
+  });
+
+  it("does not confuse a host id with a user id", async () => {
+    const context = await seed();
+    await addSetting("host", "7");
+    await addSetting("user", "7");
+
+    await new HostRepository(context).deleteForUser("user-1", 7);
+
+    expect(await remaining()).toEqual([{ scope: "user", scopeId: "7" }]);
+  });
+});

src/backend/tests/database/routes/host-plugin-settings.test.ts

@@ -0,0 +1,244 @@
+/**
+ * The pluginSettings map attached to host responses.
+ *
+ * The host editor needs these with the host, not one request per plugin per
+ * host, so the shape and the query count both matter.
+ */
+
+import { beforeEach, describe, expect, it, vi } from "vitest";
+import type { PluginManifest } from "@termix/plugin-sdk/manifest";
+
+interface Row {
+  pluginId: string;
+  scope: string;
+  scopeId: string | null;
+  key: string;
+  value: string | null;
+  encrypted: boolean;
+}
+
+const rows: Row[] = [];
+const loaded: { id: string; manifest: PluginManifest; state: string }[] = [];
+const getAllForScopeIds = vi.fn(async (scope: string, scopeIds: string[]) =>
+  rows.filter(
+    (row) => row.scope === scope && scopeIds.includes(row.scopeId ?? ""),
+  ),
+);
+
+vi.mock("../../../utils/logger.js", () => {
+  const logger = {
+    debug: vi.fn(),
+    info: vi.fn(),
+    warn: vi.fn(),
+    error: vi.fn(),
+    success: vi.fn(),
+  };
+  return { sshLogger: logger, pluginLogger: logger, databaseLogger: logger };
+});
+
+vi.mock("../../../database/repositories/factory.js", () => ({
+  createCurrentPluginSettingsRepository: () => ({ getAllForScopeIds }),
+}));
+
+vi.mock("../../../plugins/index.js", () => ({
+  getPluginRuntime: () => ({ loader: { list: () => loaded } }),
+}));
+
+vi.mock("../../../utils/system-secret-crypto.js", () => ({
+  isSystemEncrypted: (value: string) => value.startsWith("sysenc:v1:"),
+  encryptSystemSecret: async (plaintext: string) => plaintext,
+  decryptSystemSecret: async (stored: string) => stored,
+}));
+
+const {
+  attachHostPluginSettings,
+  loadHostPluginSettings,
+  withHostPluginSettings,
+} = await import("../../../database/routes/host-plugin-settings.js");
+
+function manifest(id: string, host: unknown): PluginManifest {
+  return {
+    id,
+    name: id,
+    version: "1.0.0",
+    description: "",
+    author: { name: "t" },
+    license: "MIT",
+    category: "Productivity",
+    engine: { termix: ">=2.9.0", api: "1" },
+    capabilities: [],
+    contributes: { settings: { host } },
+  } as PluginManifest;
+}
+
+const DOCKER = manifest("docker", {
+  enableKey: "enableDocker",
+  enableLabelKey: "k",
+  fields: [{ key: "socketPath", type: "string", labelKey: "k" }],
+});
+
+beforeEach(() => {
+  rows.length = 0;
+  loaded.length = 0;
+  getAllForScopeIds.mockClear();
+});
+
+describe("loadHostPluginSettings", () => {
+  it("returns nothing when no plugin declares host settings", async () => {
+    loaded.push({
+      id: "other",
+      manifest: manifest("other", undefined),
+      state: "active",
+    });
+
+    const result = await loadHostPluginSettings([1, 2]);
+
+    expect(result.size).toBe(0);
+    expect(getAllForScopeIds).not.toHaveBeenCalled();
+  });
+
+  it("ignores a plugin that is not running", async () => {
+    loaded.push({ id: "docker", manifest: DOCKER, state: "disabled" });
+
+    const result = await loadHostPluginSettings([1]);
+
+    expect(result.size).toBe(0);
+  });
+
+  it("uses one query for the whole list", async () => {
+    loaded.push({ id: "docker", manifest: DOCKER, state: "active" });
+
+    await loadHostPluginSettings([1, 2, 3, 4, 5]);
+
+    expect(getAllForScopeIds).toHaveBeenCalledTimes(1);
+    expect(getAllForScopeIds).toHaveBeenCalledWith("host", [
+      "1",
+      "2",
+      "3",
+      "4",
+      "5",
+    ]);
+  });
+
+  it("merges stored values over declared defaults", async () => {
+    loaded.push({ id: "docker", manifest: DOCKER, state: "active" });
+    rows.push({
+      pluginId: "docker",
+      scope: "host",
+      scopeId: "1",
+      key: "enableDocker",
+      value: JSON.stringify(true),
+      encrypted: false,
+    });
+
+    const result = await loadHostPluginSettings([1, 2]);
+
+    expect(result.get(1)).toEqual({
+      docker: { enableDocker: true, socketPath: undefined },
+    });
+    // Host 2 has nothing stored, so it falls back to the declared default.
+    expect(result.get(2)).toEqual({
+      docker: { enableDocker: false, socketPath: undefined },
+    });
+  });
+
+  it("keeps one host's values out of another's", async () => {
+    loaded.push({ id: "docker", manifest: DOCKER, state: "active" });
+    rows.push({
+      pluginId: "docker",
+      scope: "host",
+      scopeId: "1",
+      key: "socketPath",
+      value: JSON.stringify("/var/run/docker.sock"),
+      encrypted: false,
+    });
+
+    const result = await loadHostPluginSettings([1, 2]);
+
+    expect(result.get(1)!.docker.socketPath).toBe("/var/run/docker.sock");
+    expect(result.get(2)!.docker.socketPath).toBeUndefined();
+  });
+
+  it("redacts a host-scope secret", async () => {
+    loaded.push({
+      id: "vault",
+      manifest: manifest("vault", {
+        fields: [{ key: "token", type: "secret", labelKey: "k" }],
+      }),
+      state: "active",
+    });
+    rows.push({
+      pluginId: "vault",
+      scope: "host",
+      scopeId: "1",
+      key: "token",
+      value: JSON.stringify("s.verysecret"),
+      encrypted: true,
+    });
+
+    const result = await loadHostPluginSettings([1]);
+
+    expect(result.get(1)!.vault.token).toEqual({ set: true });
+    expect(JSON.stringify(result.get(1))).not.toContain("verysecret");
+  });
+
+  it("survives a failed settings read rather than failing the host list", async () => {
+    loaded.push({ id: "docker", manifest: DOCKER, state: "active" });
+    getAllForScopeIds.mockRejectedValueOnce(new Error("database is away"));
+
+    await expect(loadHostPluginSettings([1])).resolves.toEqual(new Map());
+  });
+
+  it("does nothing for an empty host list", async () => {
+    loaded.push({ id: "docker", manifest: DOCKER, state: "active" });
+
+    expect((await loadHostPluginSettings([])).size).toBe(0);
+    expect(getAllForScopeIds).not.toHaveBeenCalled();
+  });
+});
+
+describe("attachHostPluginSettings", () => {
+  it("attaches values to the matching host", () => {
+    const hosts = [{ id: 1 }, { id: 2 }] as Record<string, unknown>[];
+    const settings = new Map([[1, { docker: { enableDocker: true } }]]);
+
+    attachHostPluginSettings(hosts, settings);
+
+    expect(hosts[0].pluginSettings).toEqual({ docker: { enableDocker: true } });
+    expect(hosts[1].pluginSettings).toBeUndefined();
+  });
+
+  it("leaves hosts alone when there is nothing to attach", () => {
+    const hosts = [{ id: 1 }] as Record<string, unknown>[];
+
+    attachHostPluginSettings(hosts, new Map());
+
+    expect(hosts[0]).toEqual({ id: 1 });
+  });
+});
+
+describe("withHostPluginSettings", () => {
+  it("adds the map to a single host", async () => {
+    loaded.push({ id: "docker", manifest: DOCKER, state: "active" });
+
+    const result = await withHostPluginSettings({ id: 1, name: "web" });
+
+    expect(result.name).toBe("web");
+    expect(result.pluginSettings).toEqual({
+      docker: { enableDocker: false, socketPath: undefined },
+    });
+  });
+
+  it("returns the host unchanged when nothing contributes", async () => {
+    const host = { id: 1, name: "web" };
+
+    expect(await withHostPluginSettings(host)).toBe(host);
+  });
+
+  it("returns the host unchanged when its id is not a number", async () => {
+    loaded.push({ id: "docker", manifest: DOCKER, state: "active" });
+    const host = { name: "web" };
+
+    expect(await withHostPluginSettings(host)).toBe(host);
+  });
+});

src/backend/tests/plugins/settings-manifest.test.ts

@@ -0,0 +1,356 @@
+/**
+ * contributes.settings validation.
+ *
+ * A settings field is the one thing in a manifest that core writes to the
+ * database on a plugin's behalf, so the schema has to reject anything it would
+ * not know how to store or render.
+ */
+
+import { describe, expect, it } from "vitest";
+import {
+  parseManifest,
+  validateManifest,
+  SUPPORTED_PLUGIN_API_VERSION,
+} from "../../plugins/manifest.js";
+
+function base(overrides: Record<string, unknown> = {}) {
+  return {
+    id: "sample-plugin",
+    name: "Sample Plugin",
+    version: "1.0.0",
+    description: "A fixture.",
+    author: { name: "Termix Tests" },
+    license: "MIT",
+    category: "Productivity",
+    engine: { termix: ">=2.9.0", api: SUPPORTED_PLUGIN_API_VERSION },
+    capabilities: ["kv:own"],
+    ...overrides,
+  };
+}
+
+function withSettings(settings: unknown) {
+  return base({ contributes: { settings } });
+}
+
+describe("contributes.settings", () => {
+  it("accepts a manifest with every field type", () => {
+    const errors = validateManifest(
+      withSettings({
+        admin: [
+          { key: "apiKey", type: "secret", labelKey: "k" },
+          { key: "baseUrl", type: "string", labelKey: "k", default: "" },
+          { key: "retries", type: "number", labelKey: "k", min: 0, max: 5 },
+          { key: "enabled", type: "boolean", labelKey: "k" },
+          {
+            key: "mode",
+            type: "select",
+            labelKey: "k",
+            options: [{ value: "a", labelKey: "k" }],
+          },
+          {
+            key: "tags",
+            type: "multiselect",
+            labelKey: "k",
+            options: [{ value: "a", labelKey: "k" }],
+          },
+          { key: "notes", type: "textarea", labelKey: "k" },
+          { key: "raw", type: "json", labelKey: "k" },
+          { key: "browser", type: "custom", component: "devices" },
+        ],
+        user: [{ key: "theme", type: "string", labelKey: "k" }],
+        host: {
+          enableKey: "enableThing",
+          enableLabelKey: "k",
+          fields: [{ key: "port", type: "number", labelKey: "k" }],
+        },
+      }),
+    );
+
+    expect(errors).toEqual([]);
+  });
+
+  it("accepts a manifest with no settings at all", () => {
+    expect(validateManifest(base())).toEqual([]);
+  });
+
+  it("rejects an unknown field property", () => {
+    const errors = validateManifest(
+      withSettings({
+        admin: [{ key: "a", type: "string", labelKey: "k", wat: 1 }],
+      }),
+    );
+
+    expect(errors.join(" ")).toContain('Unknown field "wat"');
+  });
+
+  it("rejects an unknown scope", () => {
+    const errors = validateManifest(
+      withSettings({ global: [{ key: "a", type: "string", labelKey: "k" }] }),
+    );
+
+    expect(errors.join(" ")).toContain('Unknown field "global"');
+  });
+
+  it("rejects an unknown field type", () => {
+    const errors = validateManifest(
+      withSettings({ admin: [{ key: "a", type: "colour", labelKey: "k" }] }),
+    );
+
+    expect(errors.join(" ")).toContain("must be one of");
+  });
+
+  it("rejects a duplicate key within one scope", () => {
+    const errors = validateManifest(
+      withSettings({
+        admin: [
+          { key: "a", type: "string", labelKey: "k" },
+          { key: "a", type: "number", labelKey: "k" },
+        ],
+      }),
+    );
+
+    expect(errors.join(" ")).toContain('duplicates "a"');
+  });
+
+  it("allows the same key in two different scopes", () => {
+    const errors = validateManifest(
+      withSettings({
+        admin: [{ key: "shared", type: "string", labelKey: "k" }],
+        user: [{ key: "shared", type: "string", labelKey: "k" }],
+      }),
+    );
+
+    expect(errors).toEqual([]);
+  });
+
+  it("requires labelKey for everything but a custom field", () => {
+    expect(
+      validateManifest(
+        withSettings({ admin: [{ key: "a", type: "string" }] }),
+      ).join(" "),
+    ).toContain("labelKey");
+
+    expect(
+      validateManifest(
+        withSettings({ admin: [{ key: "a", type: "custom", component: "x" }] }),
+      ),
+    ).toEqual([]);
+  });
+
+  it("requires component on a custom field and forbids it elsewhere", () => {
+    expect(
+      validateManifest(
+        withSettings({ admin: [{ key: "a", type: "custom" }] }),
+      ).join(" "),
+    ).toContain("component");
+
+    expect(
+      validateManifest(
+        withSettings({
+          admin: [{ key: "a", type: "string", labelKey: "k", component: "x" }],
+        }),
+      ).join(" "),
+    ).toContain('only valid when type is "custom"');
+  });
+
+  it("requires non-empty options on select and multiselect", () => {
+    for (const type of ["select", "multiselect"]) {
+      expect(
+        validateManifest(
+          withSettings({ admin: [{ key: "a", type, labelKey: "k" }] }),
+        ).join(" "),
+      ).toContain("options must be a non-empty array");
+    }
+  });
+
+  it("rejects options on a field that has no options", () => {
+    const errors = validateManifest(
+      withSettings({
+        admin: [
+          {
+            key: "a",
+            type: "string",
+            labelKey: "k",
+            options: [{ value: "x", labelKey: "k" }],
+          },
+        ],
+      }),
+    );
+
+    expect(errors.join(" ")).toContain("only valid for select and multiselect");
+  });
+
+  it("rejects min greater than max", () => {
+    const errors = validateManifest(
+      withSettings({
+        admin: [{ key: "a", type: "number", labelKey: "k", min: 10, max: 1 }],
+      }),
+    );
+
+    expect(errors.join(" ")).toContain("must not be greater than");
+  });
+
+  it("rejects min or max on a non-number field", () => {
+    const errors = validateManifest(
+      withSettings({
+        admin: [{ key: "a", type: "string", labelKey: "k", min: 1 }],
+      }),
+    );
+
+    expect(errors.join(" ")).toContain("only valid for number fields");
+  });
+
+  it("rejects requires that names no boolean in the same scope", () => {
+    const errors = validateManifest(
+      withSettings({
+        admin: [
+          { key: "a", type: "string", labelKey: "k", requires: "missing" },
+        ],
+      }),
+    );
+
+    expect(errors.join(" ")).toContain("must name a boolean field");
+  });
+
+  it("rejects requires that names a non-boolean field", () => {
+    const errors = validateManifest(
+      withSettings({
+        admin: [
+          { key: "flag", type: "string", labelKey: "k" },
+          { key: "a", type: "string", labelKey: "k", requires: "flag" },
+        ],
+      }),
+    );
+
+    expect(errors.join(" ")).toContain("must name a boolean field");
+  });
+
+  it("accepts requires pointing at a boolean declared later", () => {
+    const errors = validateManifest(
+      withSettings({
+        admin: [
+          { key: "a", type: "string", labelKey: "k", requires: "flag" },
+          { key: "flag", type: "boolean", labelKey: "k" },
+        ],
+      }),
+    );
+
+    expect(errors).toEqual([]);
+  });
+
+  it("lets a host field require the section's enable key", () => {
+    const errors = validateManifest(
+      withSettings({
+        host: {
+          enableKey: "enableThing",
+          enableLabelKey: "k",
+          fields: [
+            {
+              key: "port",
+              type: "number",
+              labelKey: "k",
+              requires: "enableThing",
+            },
+          ],
+        },
+      }),
+    );
+
+    expect(errors).toEqual([]);
+  });
+
+  it("rejects a host field colliding with the enable key", () => {
+    const errors = validateManifest(
+      withSettings({
+        host: {
+          enableKey: "enableThing",
+          enableLabelKey: "k",
+          fields: [{ key: "enableThing", type: "boolean", labelKey: "k" }],
+        },
+      }),
+    );
+
+    expect(errors.join(" ")).toContain("already the section's enableKey");
+  });
+
+  it("requires enableLabelKey alongside enableKey", () => {
+    const errors = validateManifest(
+      withSettings({
+        host: { enableKey: "enableThing", fields: [] },
+      }),
+    );
+
+    expect(errors.join(" ")).toContain("enableLabelKey");
+  });
+
+  it("rejects a key that would not be index-safe", () => {
+    const errors = validateManifest(
+      withSettings({
+        admin: [{ key: "a".repeat(80), type: "string", labelKey: "k" }],
+      }),
+    );
+
+    expect(errors.join(" ")).toContain("short alphanumeric key");
+  });
+});
+
+describe("settings field permissions", () => {
+  it("rejects a short permission the plugin does not declare", () => {
+    const { errors } = parseManifest(
+      base({
+        contributes: {
+          settings: {
+            user: [
+              { key: "a", type: "string", labelKey: "k", permission: "use" },
+            ],
+          },
+        },
+      }),
+    );
+
+    expect(errors.join(" ")).toContain(
+      "not declared in contributes.permissions",
+    );
+  });
+
+  it("accepts a short permission the plugin declares", () => {
+    const { errors, manifest } = parseManifest(
+      base({
+        contributes: {
+          permissions: [{ name: "use", titleKey: "k", descriptionKey: "k" }],
+          settings: {
+            user: [
+              { key: "a", type: "string", labelKey: "k", permission: "use" },
+            ],
+          },
+        },
+      }),
+    );
+
+    expect(errors).toEqual([]);
+    expect(manifest?.contributes?.settings?.user?.[0].permission).toBe("use");
+  });
+
+  it("accepts a fully qualified permission from another namespace", () => {
+    // Cross-namespace ids cannot be checked here: the validator has no idea
+    // which other plugins exist. Taken as given, exactly like ctx.rbac does.
+    const { errors } = parseManifest(
+      base({
+        contributes: {
+          settings: {
+            user: [
+              {
+                key: "a",
+                type: "string",
+                labelKey: "k",
+                permission: "hosts.view",
+              },
+            ],
+          },
+        },
+      }),
+    );
+
+    expect(errors).toEqual([]);
+  });
+});

src/backend/tests/plugins/settings-routes.test.ts

@@ -0,0 +1,498 @@
+/**
+ * The /plugins/:id/settings routes.
+ *
+ * These decide who may change what, so the tests are mostly about refusal: a
+ * non-admin must not write install-wide configuration, a user must not write
+ * another user's settings or a host they cannot edit, and a secret must never
+ * come back over the wire.
+ */
+
+import { afterEach, beforeEach, describe, expect, it, vi } from "vitest";
+import express from "express";
+import type { AddressInfo } from "node:net";
+import type { Server } from "node:http";
+import type { PluginManifest } from "@termix/plugin-sdk/manifest";
+
+const state = vi.hoisted(() => ({
+  userId: "user-1",
+  permissions: new Set<string>(),
+  hostEditAccess: true,
+}));
+
+vi.mock("../../utils/logger.js", () => {
+  const logger = {
+    debug: vi.fn(),
+    info: vi.fn(),
+    warn: vi.fn(),
+    error: vi.fn(),
+    success: vi.fn(),
+  };
+  return { pluginLogger: logger, databaseLogger: logger, apiLogger: logger };
+});
+
+vi.mock("../../utils/auth-manager.js", () => ({
+  AuthManager: {
+    getInstance: () => ({
+      createAuthMiddleware:
+        () =>
+        (
+          req: express.Request,
+          res: express.Response,
+          next: express.NextFunction,
+        ) => {
+          (req as express.Request & { userId?: string }).userId = state.userId;
+          next();
+        },
+    }),
+  },
+}));
+
+vi.mock("../../utils/permission-manager.js", () => ({
+  PermissionManager: {
+    getInstance: () => ({
+      hasPermission: async (_userId: string, permission: string) =>
+        state.permissions.has(permission),
+      requirePermission:
+        (permission: string) =>
+        (
+          _req: express.Request,
+          res: express.Response,
+          next: express.NextFunction,
+        ) => {
+          if (!state.permissions.has(permission)) {
+            res.status(403).json({ error: "Insufficient permissions" });
+            return;
+          }
+          next();
+        },
+      canAccessHost: async () => ({
+        hasAccess: state.hostEditAccess,
+        isOwner: state.hostEditAccess,
+        isShared: false,
+      }),
+    }),
+  },
+}));
+
+vi.mock("../../utils/audit-logger.js", () => ({
+  logAudit: vi.fn(async () => {}),
+  getAuditUsername: vi.fn(async (id: string) => id),
+  getRequestMeta: () => ({ ipAddress: "127.0.0.1", userAgent: "test" }),
+}));
+
+const MANIFEST: PluginManifest = {
+  id: "sample",
+  name: "Sample",
+  version: "1.0.0",
+  description: "",
+  author: { name: "t" },
+  license: "MIT",
+  category: "Productivity",
+  engine: { termix: ">=2.9.0", api: "1" },
+  capabilities: [],
+  contributes: {
+    permissions: [{ name: "tweak", titleKey: "k", descriptionKey: "k" }],
+    settings: {
+      admin: [
+        { key: "apiKey", type: "secret", labelKey: "k" },
+        { key: "retries", type: "number", labelKey: "k", min: 0, max: 5 },
+        {
+          key: "narrowed",
+          type: "string",
+          labelKey: "k",
+          permission: "tweak",
+        },
+      ],
+      user: [
+        { key: "theme", type: "string", labelKey: "k", default: "dark" },
+        {
+          key: "advanced",
+          type: "string",
+          labelKey: "k",
+          permission: "tweak",
+        },
+      ],
+      host: {
+        enableKey: "enableThing",
+        enableLabelKey: "k",
+        fields: [{ key: "port", type: "number", labelKey: "k" }],
+      },
+    },
+  },
+} as PluginManifest;
+
+vi.mock("../../plugins/index.js", () => ({
+  getPluginRuntime: () => ({
+    loader: {
+      get: (id: string) =>
+        id === "sample"
+          ? { id, manifest: MANIFEST, state: "active" }
+          : undefined,
+      list: () => [{ id: "sample", manifest: MANIFEST, state: "active" }],
+    },
+  }),
+}));
+
+interface Row {
+  pluginId: string;
+  scope: string;
+  scopeId: string | null;
+  key: string;
+  value: string | null;
+  encrypted: boolean;
+}
+
+const rows: Row[] = [];
+
+function find(scope: string, scopeId: string | null, key: string) {
+  return rows.find(
+    (row) => row.scope === scope && row.scopeId === scopeId && row.key === key,
+  );
+}
+
+vi.mock("../../database/repositories/factory.js", () => ({
+  createCurrentPluginRepository: () => ({
+    findById: async (id: string) =>
+      id === "sample"
+        ? { id, manifestJson: JSON.stringify(MANIFEST), state: "enabled" }
+        : null,
+    listAll: async () => [],
+  }),
+  createCurrentPluginPermissionGrantRepository: () => ({
+    listByPlugin: async () => [],
+  }),
+  createCurrentPluginSettingsRepository: () => ({
+    get: async (
+      _pluginId: string,
+      scope: string,
+      scopeId: string | null,
+      key: string,
+    ) => find(scope, scopeId, key) ?? null,
+    getAll: async (_pluginId: string, scope: string, scopeId: string | null) =>
+      rows.filter((row) => row.scope === scope && row.scopeId === scopeId),
+    set: async (
+      pluginId: string,
+      scope: string,
+      scopeId: string | null,
+      key: string,
+      value: string | null,
+      encrypted = false,
+    ) => {
+      const existing = find(scope, scopeId, key);
+      if (existing) {
+        existing.value = value;
+        existing.encrypted = encrypted;
+        return;
+      }
+      rows.push({ pluginId, scope, scopeId, key, value, encrypted });
+    },
+  }),
+  createCurrentSettingsRepository: () => ({ get: async () => null }),
+}));
+
+vi.mock("../../utils/system-secret-crypto.js", () => ({
+  isSystemEncrypted: (value: string) => value.startsWith("sysenc:v1:"),
+  encryptSystemSecret: async (plaintext: string) =>
+    !plaintext || plaintext.startsWith("sysenc:v1:")
+      ? plaintext
+      : `sysenc:v1:${Buffer.from(plaintext, "utf8").toString("base64")}`,
+  decryptSystemSecret: async (stored: string) =>
+    stored.startsWith("sysenc:v1:")
+      ? Buffer.from(stored.slice("sysenc:v1:".length), "base64").toString(
+          "utf8",
+        )
+      : stored,
+}));
+
+const pluginRoutes = (await import("../../database/routes/plugins.js")).default;
+
+let server: Server;
+let baseUrl: string;
+
+beforeEach(async () => {
+  rows.length = 0;
+  state.userId = "user-1";
+  state.permissions = new Set<string>();
+  state.hostEditAccess = true;
+
+  const app = express();
+  app.use(express.json());
+  app.use("/plugins", pluginRoutes);
+
+  server = await new Promise<Server>((resolve) => {
+    const created = app.listen(0, "127.0.0.1", () => resolve(created));
+  });
+  baseUrl = `http://127.0.0.1:${(server.address() as AddressInfo).port}`;
+});
+
+afterEach(async () => {
+  await new Promise<void>((resolve) => server.close(() => resolve()));
+});
+
+function call(path: string, init?: RequestInit) {
+  return fetch(`${baseUrl}${path}`, {
+    ...init,
+    headers: { "content-type": "application/json", ...(init?.headers ?? {}) },
+  });
+}
+
+describe("admin scope", () => {
+  it("refuses a reader without admin.plugins.manage", async () => {
+    const response = await call("/plugins/sample/settings/admin");
+
+    expect(response.status).toBe(403);
+  });
+
+  it("refuses a writer without admin.plugins.manage", async () => {
+    const response = await call("/plugins/sample/settings/admin", {
+      method: "PUT",
+      body: JSON.stringify({ retries: 2 }),
+    });
+
+    expect(response.status).toBe(403);
+    expect(rows).toHaveLength(0);
+  });
+
+  it("lets an admin read and write", async () => {
+    state.permissions.add("admin.plugins.manage");
+
+    const write = await call("/plugins/sample/settings/admin", {
+      method: "PUT",
+      body: JSON.stringify({ retries: 3 }),
+    });
+    expect(write.status).toBe(200);
+
+    const read = await call("/plugins/sample/settings/admin");
+    expect((await read.json()).values.retries).toBe(3);
+  });
+
+  it("reports a rejected value per field", async () => {
+    state.permissions.add("admin.plugins.manage");
+
+    const response = await call("/plugins/sample/settings/admin", {
+      method: "PUT",
+      body: JSON.stringify({ retries: 99 }),
+    });
+
+    expect(response.status).toBe(400);
+    expect((await response.json()).errors.retries).toContain("at most 5");
+    expect(rows).toHaveLength(0);
+  });
+
+  it("refuses a key the manifest never declared", async () => {
+    state.permissions.add("admin.plugins.manage");
+
+    const response = await call("/plugins/sample/settings/admin", {
+      method: "PUT",
+      body: JSON.stringify({ somethingElse: "x" }),
+    });
+
+    expect(response.status).toBe(400);
+    expect((await response.json()).errors.somethingElse).toBeDefined();
+    expect(rows).toHaveLength(0);
+  });
+
+  it("never returns a secret's value", async () => {
+    state.permissions.add("admin.plugins.manage");
+
+    await call("/plugins/sample/settings/admin", {
+      method: "PUT",
+      body: JSON.stringify({ apiKey: "tskey-very-secret" }),
+    });
+
+    const response = await call("/plugins/sample/settings/admin");
+    const body = await response.text();
+
+    expect(body).not.toContain("tskey-very-secret");
+    expect(JSON.parse(body).values.apiKey).toEqual({ set: true });
+  });
+
+  it("treats a redacted echo as no change", async () => {
+    state.permissions.add("admin.plugins.manage");
+
+    await call("/plugins/sample/settings/admin", {
+      method: "PUT",
+      body: JSON.stringify({ apiKey: "tskey-original" }),
+    });
+    await call("/plugins/sample/settings/admin", {
+      method: "PUT",
+      body: JSON.stringify({ apiKey: { set: true }, retries: 1 }),
+    });
+
+    const row = rows.find((entry) => entry.key === "apiKey")!;
+    expect(
+      Buffer.from(
+        JSON.parse(row.value!).slice("sysenc:v1:".length),
+        "base64",
+      ).toString("utf8"),
+    ).toBe("tskey-original");
+  });
+
+  it("keeps the admin gate even for a field naming its own permission", async () => {
+    // Holding the field's permission is not enough: admin scope is admin
+    // scope, so a plugin cannot hand install-wide config to an ordinary user.
+    state.permissions.add("sample.tweak");
+
+    const response = await call("/plugins/sample/settings/admin", {
+      method: "PUT",
+      body: JSON.stringify({ narrowed: "x" }),
+    });
+
+    expect(response.status).toBe(403);
+    expect(rows).toHaveLength(0);
+  });
+
+  it("narrows an admin field to holders of its permission", async () => {
+    state.permissions.add("admin.plugins.manage");
+
+    const denied = await call("/plugins/sample/settings/admin", {
+      method: "PUT",
+      body: JSON.stringify({ narrowed: "x" }),
+    });
+    expect(denied.status).toBe(400);
+    expect((await denied.json()).errors.narrowed).toContain("permission");
+
+    state.permissions.add("sample.tweak");
+    const allowed = await call("/plugins/sample/settings/admin", {
+      method: "PUT",
+      body: JSON.stringify({ narrowed: "x" }),
+    });
+    expect(allowed.status).toBe(200);
+  });
+
+  it("404s for a plugin that does not exist", async () => {
+    state.permissions.add("admin.plugins.manage");
+
+    const response = await call("/plugins/nope/settings/admin");
+
+    expect(response.status).toBe(404);
+  });
+
+  it("rejects a body that is not an object", async () => {
+    state.permissions.add("admin.plugins.manage");
+
+    const response = await call("/plugins/sample/settings/admin", {
+      method: "PUT",
+      body: JSON.stringify([1, 2, 3]),
+    });
+
+    expect(response.status).toBe(400);
+  });
+});
+
+describe("user scope", () => {
+  it("lets any authenticated user read and write their own", async () => {
+    const write = await call("/plugins/sample/settings/user", {
+      method: "PUT",
+      body: JSON.stringify({ theme: "light" }),
+    });
+    expect(write.status).toBe(200);
+
+    const read = await call("/plugins/sample/settings/user");
+    expect((await read.json()).values.theme).toBe("light");
+  });
+
+  it("scopes writes to the caller, never to a user id in the body", async () => {
+    await call("/plugins/sample/settings/user", {
+      method: "PUT",
+      body: JSON.stringify({ theme: "light", userId: "someone-else" }),
+    });
+
+    // The bogus key is rejected and the row belongs to the caller.
+    expect(rows.every((row) => row.scopeId === "user-1")).toBe(true);
+
+    state.userId = "user-2";
+    const other = await call("/plugins/sample/settings/user");
+    expect((await other.json()).values.theme).toBe("dark");
+  });
+
+  it("refuses a user field gated on a permission the caller lacks", async () => {
+    const response = await call("/plugins/sample/settings/user", {
+      method: "PUT",
+      body: JSON.stringify({ advanced: "x" }),
+    });
+
+    expect(response.status).toBe(400);
+    expect((await response.json()).errors.advanced).toContain("permission");
+    expect(rows).toHaveLength(0);
+  });
+
+  it("allows it once the caller holds that permission", async () => {
+    state.permissions.add("sample.tweak");
+
+    const response = await call("/plugins/sample/settings/user", {
+      method: "PUT",
+      body: JSON.stringify({ advanced: "x" }),
+    });
+
+    expect(response.status).toBe(200);
+  });
+
+  it("refuses an admin field through the user route", async () => {
+    const response = await call("/plugins/sample/settings/user", {
+      method: "PUT",
+      body: JSON.stringify({ apiKey: "nope" }),
+    });
+
+    expect(response.status).toBe(400);
+    expect(rows).toHaveLength(0);
+  });
+});
+
+describe("host scope", () => {
+  it("lets a user with edit access read and write", async () => {
+    const write = await call("/plugins/sample/settings/host/7", {
+      method: "PUT",
+      body: JSON.stringify({ enableThing: true, port: 22 }),
+    });
+    expect(write.status).toBe(200);
+
+    const read = await call("/plugins/sample/settings/host/7");
+    const values = (await read.json()).values;
+    expect(values.enableThing).toBe(true);
+    expect(values.port).toBe(22);
+  });
+
+  it("refuses a host the caller cannot edit", async () => {
+    state.hostEditAccess = false;
+
+    const read = await call("/plugins/sample/settings/host/7");
+    expect(read.status).toBe(403);
+
+    const write = await call("/plugins/sample/settings/host/7", {
+      method: "PUT",
+      body: JSON.stringify({ port: 22 }),
+    });
+    expect(write.status).toBe(403);
+    expect(rows).toHaveLength(0);
+  });
+
+  it("rejects an invalid host id", async () => {
+    const response = await call("/plugins/sample/settings/host/not-a-number");
+
+    expect(response.status).toBe(400);
+  });
+
+  it("keeps each host's values apart", async () => {
+    await call("/plugins/sample/settings/host/7", {
+      method: "PUT",
+      body: JSON.stringify({ port: 22 }),
+    });
+    await call("/plugins/sample/settings/host/8", {
+      method: "PUT",
+      body: JSON.stringify({ port: 2222 }),
+    });
+
+    const seven = await (await call("/plugins/sample/settings/host/7")).json();
+    const eight = await (await call("/plugins/sample/settings/host/8")).json();
+
+    expect(seven.values.port).toBe(22);
+    expect(eight.values.port).toBe(2222);
+  });
+
+  it("returns the declared default for an untouched host", async () => {
+    const response = await call("/plugins/sample/settings/host/9");
+
+    expect((await response.json()).values.enableThing).toBe(false);
+  });
+});

src/backend/tests/plugins/settings.test.ts

@@ -0,0 +1,442 @@
+/**
+ * The plugin settings service.
+ *
+ * Storage is faked at the repository boundary; everything above it - schema
+ * lookup, validation, encryption, redaction and change notification - is the
+ * real implementation, because that is where the behaviour worth protecting
+ * lives.
+ */
+
+import { beforeEach, describe, expect, it, vi } from "vitest";
+import type { PluginManifest } from "@termix/plugin-sdk/manifest";
+
+interface Row {
+  pluginId: string;
+  scope: string;
+  scopeId: string | null;
+  key: string;
+  value: string | null;
+  encrypted: boolean;
+}
+
+const rows: Row[] = [];
+
+function find(
+  pluginId: string,
+  scope: string,
+  scopeId: string | null,
+  key: string,
+) {
+  return rows.find(
+    (row) =>
+      row.pluginId === pluginId &&
+      row.scope === scope &&
+      row.scopeId === scopeId &&
+      row.key === key,
+  );
+}
+
+const settingsRepository = {
+  get: vi.fn(
+    async (
+      pluginId: string,
+      scope: string,
+      scopeId: string | null,
+      key: string,
+    ) => find(pluginId, scope, scopeId, key) ?? null,
+  ),
+  getAll: vi.fn(
+    async (pluginId: string, scope: string, scopeId: string | null) =>
+      rows.filter(
+        (row) =>
+          row.pluginId === pluginId &&
+          row.scope === scope &&
+          row.scopeId === scopeId,
+      ),
+  ),
+  set: vi.fn(
+    async (
+      pluginId: string,
+      scope: string,
+      scopeId: string | null,
+      key: string,
+      value: string | null,
+      encrypted = false,
+    ) => {
+      const existing = find(pluginId, scope, scopeId, key);
+      if (existing) {
+        existing.value = value;
+        existing.encrypted = encrypted;
+        return;
+      }
+      rows.push({ pluginId, scope, scopeId, key, value, encrypted });
+    },
+  ),
+};
+
+const coreSettings = new Map<string, string>();
+
+vi.mock("../../database/repositories/factory.js", () => ({
+  createCurrentPluginSettingsRepository: () => settingsRepository,
+  createCurrentSettingsRepository: () => ({
+    get: async (key: string) => coreSettings.get(key) ?? null,
+  }),
+}));
+
+// Real AES would need the system key on disk. The prefix and the idempotence
+// are what the service depends on, so the double keeps both.
+vi.mock("../../utils/system-secret-crypto.js", () => ({
+  isSystemEncrypted: (value: string) => value.startsWith("sysenc:v1:"),
+  encryptSystemSecret: async (plaintext: string) =>
+    !plaintext || plaintext.startsWith("sysenc:v1:")
+      ? plaintext
+      : `sysenc:v1:${Buffer.from(plaintext, "utf8").toString("base64")}`,
+  decryptSystemSecret: async (stored: string) =>
+    stored.startsWith("sysenc:v1:")
+      ? Buffer.from(stored.slice("sysenc:v1:".length), "base64").toString(
+          "utf8",
+        )
+      : stored,
+}));
+
+const {
+  CORE_SETTINGS_ALLOWLIST,
+  clearSettingsListeners,
+  declaredFields,
+  findField,
+  getAllSettings,
+  getSetting,
+  onSettingsChange,
+  readCoreSetting,
+  setSetting,
+} = await import("../../plugins/settings.js");
+
+function manifest(settings: unknown): PluginManifest {
+  return {
+    id: "sample",
+    name: "Sample",
+    version: "1.0.0",
+    description: "",
+    author: { name: "t" },
+    license: "MIT",
+    category: "Productivity",
+    engine: { termix: ">=2.9.0", api: "1" },
+    capabilities: [],
+    contributes: { settings },
+  } as PluginManifest;
+}
+
+const ADMIN = manifest({
+  admin: [
+    { key: "apiKey", type: "secret", labelKey: "k" },
+    { key: "baseUrl", type: "string", labelKey: "k", default: "https://x" },
+    { key: "retries", type: "number", labelKey: "k", min: 0, max: 5 },
+    { key: "enabled", type: "boolean", labelKey: "k", default: false },
+    {
+      key: "mode",
+      type: "select",
+      labelKey: "k",
+      options: [
+        { value: "fast", labelKey: "k" },
+        { value: "slow", labelKey: "k" },
+      ],
+    },
+  ],
+});
+
+beforeEach(() => {
+  rows.length = 0;
+  coreSettings.clear();
+  clearSettingsListeners("sample");
+  vi.clearAllMocks();
+});
+
+describe("declaredFields", () => {
+  it("returns the fields for each scope", () => {
+    expect(declaredFields(ADMIN, "admin").map((f) => f.key)).toEqual([
+      "apiKey",
+      "baseUrl",
+      "retries",
+      "enabled",
+      "mode",
+    ]);
+    expect(declaredFields(ADMIN, "user")).toEqual([]);
+  });
+
+  it("treats the host enable key as a real boolean field", () => {
+    const withHost = manifest({
+      host: {
+        enableKey: "enableThing",
+        enableLabelKey: "k",
+        fields: [{ key: "port", type: "number", labelKey: "k" }],
+      },
+    });
+
+    const fields = declaredFields(withHost, "host");
+    expect(fields.map((f) => f.key)).toEqual(["enableThing", "port"]);
+    expect(fields[0]).toMatchObject({ type: "boolean", default: false });
+  });
+
+  it("finds a field by key", () => {
+    expect(findField(ADMIN, "admin", "baseUrl")?.type).toBe("string");
+    expect(findField(ADMIN, "admin", "nope")).toBeUndefined();
+  });
+});
+
+describe("setSetting", () => {
+  it("writes a valid value and reads it back", async () => {
+    expect(
+      await setSetting(ADMIN, "admin", null, "baseUrl", "https://y"),
+    ).toBeNull();
+    expect(await getSetting(ADMIN, "admin", null, "baseUrl")).toBe("https://y");
+  });
+
+  it("refuses a key the manifest never declared", async () => {
+    const error = await setSetting(ADMIN, "admin", null, "wat", "x");
+
+    expect(error).toContain("not a settings field this plugin declares");
+    expect(rows).toHaveLength(0);
+  });
+
+  it("refuses a value that fails the declared constraint", async () => {
+    expect(await setSetting(ADMIN, "admin", null, "retries", 99)).toContain(
+      "at most 5",
+    );
+    expect(
+      await setSetting(ADMIN, "admin", null, "mode", "sideways"),
+    ).toContain("must be one of");
+    expect(rows).toHaveLength(0);
+  });
+
+  it("coerces the strings a form actually sends", async () => {
+    expect(await setSetting(ADMIN, "admin", null, "retries", "3")).toBeNull();
+    expect(await getSetting(ADMIN, "admin", null, "retries")).toBe(3);
+
+    expect(
+      await setSetting(ADMIN, "admin", null, "enabled", "true"),
+    ).toBeNull();
+    expect(await getSetting(ADMIN, "admin", null, "enabled")).toBe(true);
+  });
+
+  it("keeps each scope separate", async () => {
+    const scoped = manifest({
+      admin: [{ key: "v", type: "string", labelKey: "k" }],
+      user: [{ key: "v", type: "string", labelKey: "k" }],
+      host: { fields: [{ key: "v", type: "string", labelKey: "k" }] },
+    });
+
+    await setSetting(scoped, "admin", null, "v", "a");
+    await setSetting(scoped, "user", "user-1", "v", "u");
+    await setSetting(scoped, "host", 7, "v", "h");
+
+    expect(await getSetting(scoped, "admin", null, "v")).toBe("a");
+    expect(await getSetting(scoped, "user", "user-1", "v")).toBe("u");
+    expect(await getSetting(scoped, "host", 7, "v")).toBe("h");
+    // A different user sees nothing of the first user's value.
+    expect(await getSetting(scoped, "user", "user-2", "v")).toBeUndefined();
+  });
+
+  it("stores a host id as text, matching the polymorphic scope column", async () => {
+    const scoped = manifest({
+      host: { fields: [{ key: "v", type: "string", labelKey: "k" }] },
+    });
+
+    await setSetting(scoped, "host", 12, "v", "x");
+
+    expect(rows[0].scopeId).toBe("12");
+    // Either spelling resolves to the same row.
+    expect(await getSetting(scoped, "host", "12", "v")).toBe("x");
+  });
+});
+
+describe("defaults", () => {
+  it("falls back to the declared default when nothing is stored", async () => {
+    expect(await getSetting(ADMIN, "admin", null, "baseUrl")).toBe("https://x");
+    expect(await getSetting(ADMIN, "admin", null, "enabled")).toBe(false);
+  });
+
+  it("returns undefined for a field with no default and no value", async () => {
+    expect(await getSetting(ADMIN, "admin", null, "retries")).toBeUndefined();
+  });
+
+  it("returns undefined for a key the manifest does not declare", async () => {
+    expect(await getSetting(ADMIN, "admin", null, "wat")).toBeUndefined();
+  });
+});
+
+describe("secrets", () => {
+  it("encrypts on the way in and decrypts on the way out", async () => {
+    await setSetting(ADMIN, "admin", null, "apiKey", "tskey-secret");
+
+    const row = rows.find((entry) => entry.key === "apiKey")!;
+    expect(row.encrypted).toBe(true);
+    expect(row.value).not.toContain("tskey-secret");
+    expect(JSON.parse(row.value!)).toMatch(/^sysenc:v1:/);
+
+    expect(await getSetting(ADMIN, "admin", null, "apiKey")).toBe(
+      "tskey-secret",
+    );
+  });
+
+  it("redacts a secret rather than returning it", async () => {
+    await setSetting(ADMIN, "admin", null, "apiKey", "tskey-secret");
+
+    const values = await getAllSettings(ADMIN, "admin", null, {
+      redactSecrets: true,
+    });
+
+    expect(values.apiKey).toEqual({ set: true });
+    expect(JSON.stringify(values)).not.toContain("tskey-secret");
+  });
+
+  it("reports an unset secret as set:false", async () => {
+    const values = await getAllSettings(ADMIN, "admin", null, {
+      redactSecrets: true,
+    });
+
+    expect(values.apiKey).toEqual({ set: false });
+  });
+
+  it("treats a redacted echo as leave-it-alone", async () => {
+    await setSetting(ADMIN, "admin", null, "apiKey", "original");
+
+    expect(
+      await setSetting(ADMIN, "admin", null, "apiKey", { set: true }),
+    ).toBeNull();
+
+    expect(await getSetting(ADMIN, "admin", null, "apiKey")).toBe("original");
+  });
+
+  it("lets a secret be replaced and cleared", async () => {
+    await setSetting(ADMIN, "admin", null, "apiKey", "first");
+    await setSetting(ADMIN, "admin", null, "apiKey", "second");
+    expect(await getSetting(ADMIN, "admin", null, "apiKey")).toBe("second");
+
+    await setSetting(ADMIN, "admin", null, "apiKey", "");
+    const values = await getAllSettings(ADMIN, "admin", null, {
+      redactSecrets: true,
+    });
+    expect(values.apiKey).toEqual({ set: false });
+  });
+
+  it("hands a plugin its own secret in the clear", async () => {
+    await setSetting(ADMIN, "admin", null, "apiKey", "tskey-secret");
+
+    const values = await getAllSettings(ADMIN, "admin", null);
+
+    expect(values.apiKey).toBe("tskey-secret");
+  });
+});
+
+describe("getAllSettings", () => {
+  it("is driven by the manifest, not by the stored rows", async () => {
+    await setSetting(ADMIN, "admin", null, "baseUrl", "https://y");
+    // A row for a field the plugin has since dropped.
+    rows.push({
+      pluginId: "sample",
+      scope: "admin",
+      scopeId: null,
+      key: "removedField",
+      value: JSON.stringify("stale"),
+      encrypted: false,
+    });
+
+    const values = await getAllSettings(ADMIN, "admin", null);
+
+    expect(values.baseUrl).toBe("https://y");
+    expect(values.enabled).toBe(false);
+    expect(values).not.toHaveProperty("removedField");
+  });
+
+  it("returns nothing for a scope the plugin declares no fields in", async () => {
+    expect(await getAllSettings(ADMIN, "user", "user-1")).toEqual({});
+  });
+});
+
+describe("onSettingsChange", () => {
+  it("fires on a successful write", async () => {
+    const listener = vi.fn();
+    onSettingsChange("sample", "baseUrl", listener);
+
+    await setSetting(ADMIN, "admin", null, "baseUrl", "https://z");
+
+    expect(listener).toHaveBeenCalledWith("https://z");
+  });
+
+  it("does not fire for a rejected write", async () => {
+    const listener = vi.fn();
+    onSettingsChange("sample", "retries", listener);
+
+    await setSetting(ADMIN, "admin", null, "retries", 99);
+
+    expect(listener).not.toHaveBeenCalled();
+  });
+
+  it("stops firing once unsubscribed", async () => {
+    const listener = vi.fn();
+    const unsubscribe = onSettingsChange("sample", "baseUrl", listener);
+
+    unsubscribe();
+    await setSetting(ADMIN, "admin", null, "baseUrl", "https://z");
+
+    expect(listener).not.toHaveBeenCalled();
+  });
+
+  it("only notifies listeners for that key and plugin", async () => {
+    const other = vi.fn();
+    const another = vi.fn();
+    onSettingsChange("sample", "enabled", other);
+    onSettingsChange("different-plugin", "baseUrl", another);
+
+    await setSetting(ADMIN, "admin", null, "baseUrl", "https://z");
+
+    expect(other).not.toHaveBeenCalled();
+    expect(another).not.toHaveBeenCalled();
+    clearSettingsListeners("different-plugin");
+  });
+
+  it("survives a listener that throws", async () => {
+    const good = vi.fn();
+    onSettingsChange("sample", "baseUrl", () => {
+      throw new Error("listener blew up");
+    });
+    onSettingsChange("sample", "baseUrl", good);
+
+    await expect(
+      setSetting(ADMIN, "admin", null, "baseUrl", "https://z"),
+    ).resolves.toBeNull();
+    expect(good).toHaveBeenCalled();
+  });
+
+  it("drops every listener when the plugin deactivates", async () => {
+    const listener = vi.fn();
+    onSettingsChange("sample", "baseUrl", listener);
+
+    clearSettingsListeners("sample");
+    await setSetting(ADMIN, "admin", null, "baseUrl", "https://z");
+
+    expect(listener).not.toHaveBeenCalled();
+  });
+});
+
+describe("readCoreSetting", () => {
+  it("returns an allowlisted key", async () => {
+    coreSettings.set("app_name", "Termix");
+
+    expect(await readCoreSetting("app_name")).toBe("Termix");
+  });
+
+  it("refuses a key that is not on the allowlist", async () => {
+    coreSettings.set("jwt_secret", "nope");
+
+    await expect(readCoreSetting("jwt_secret")).rejects.toThrow(
+      /not readable by plugins/,
+    );
+  });
+
+  it("does not expose anything sensitive through the allowlist", () => {
+    for (const key of CORE_SETTINGS_ALLOWLIST) {
+      expect(key).not.toMatch(/secret|password|token|key$/i);
+    }
+  });
+});

src/backend/tests/utils/tailscale-settings-migration.test.ts

@@ -0,0 +1,228 @@
+/**
+ * The Tailscale settings migration.
+ *
+ * An upgrade must be lossless: an install that had a working API key must keep
+ * working without anyone re-entering it. That is the whole point of the test,
+ * and running it twice proves a restart cannot corrupt what it moved.
+ */
+
+import { beforeEach, describe, expect, it, vi } from "vitest";
+
+interface Row {
+  pluginId: string;
+  scope: string;
+  scopeId: string | null;
+  key: string;
+  value: string | null;
+  encrypted: boolean;
+}
+
+const coreSettings = new Map<string, string>();
+const pluginRows: Row[] = [];
+let pluginInstalled = true;
+
+const pluginSettingsRepository = {
+  get: async (
+    pluginId: string,
+    scope: string,
+    scopeId: string | null,
+    key: string,
+  ) =>
+    pluginRows.find(
+      (row) =>
+        row.pluginId === pluginId &&
+        row.scope === scope &&
+        row.scopeId === scopeId &&
+        row.key === key,
+    ) ?? null,
+  set: async (
+    pluginId: string,
+    scope: string,
+    scopeId: string | null,
+    key: string,
+    value: string | null,
+    encrypted = false,
+  ) => {
+    const existing = pluginRows.find(
+      (row) =>
+        row.pluginId === pluginId &&
+        row.scope === scope &&
+        row.scopeId === scopeId &&
+        row.key === key,
+    );
+    if (existing) {
+      existing.value = value;
+      existing.encrypted = encrypted;
+      return;
+    }
+    pluginRows.push({ pluginId, scope, scopeId, key, value, encrypted });
+  },
+};
+
+vi.mock("../../database/repositories/factory.js", () => ({
+  createCurrentPluginRepository: () => ({
+    findById: async (id: string) =>
+      pluginInstalled && id === "tailscale" ? { id } : null,
+  }),
+  createCurrentPluginSettingsRepository: () => pluginSettingsRepository,
+  createCurrentSettingsRepository: () => ({
+    get: async (key: string) => coreSettings.get(key) ?? null,
+    delete: async (key: string) => coreSettings.delete(key),
+  }),
+}));
+
+vi.mock("../../utils/system-secret-crypto.js", () => ({
+  isSystemEncrypted: (value: string) => value.startsWith("sysenc:v1:"),
+  encryptSystemSecret: async (plaintext: string) =>
+    !plaintext || plaintext.startsWith("sysenc:v1:")
+      ? plaintext
+      : `sysenc:v1:${Buffer.from(plaintext, "utf8").toString("base64")}`,
+  decryptSystemSecret: async (stored: string) =>
+    stored.startsWith("sysenc:v1:")
+      ? Buffer.from(stored.slice("sysenc:v1:".length), "base64").toString(
+          "utf8",
+        )
+      : stored,
+}));
+
+const { runTailscaleSettingsMigration } =
+  await import("../../utils/crypto-migration/tailscale-settings-migration.js");
+
+function storedValue(key: string): unknown {
+  const row = pluginRows.find((entry) => entry.key === key);
+  return row?.value === null || row?.value === undefined
+    ? undefined
+    : JSON.parse(row.value);
+}
+
+beforeEach(() => {
+  coreSettings.clear();
+  pluginRows.length = 0;
+  pluginInstalled = true;
+});
+
+describe("runTailscaleSettingsMigration", () => {
+  it("moves an existing key and base URL into plugin settings", async () => {
+    coreSettings.set("tailscale_api_key", "tskey-api-legacy");
+    coreSettings.set("tailscale_api_base_url", "https://headscale.example");
+
+    const result = await runTailscaleSettingsMigration();
+
+    expect(result.moved).toEqual([
+      "tailscale_api_key",
+      "tailscale_api_base_url",
+    ]);
+    expect(storedValue("apiKey")).toMatch(/^sysenc:v1:/);
+    expect(storedValue("apiBaseUrl")).toBe("https://headscale.example");
+  });
+
+  it("encrypts the key, which was stored in plaintext before", async () => {
+    coreSettings.set("tailscale_api_key", "tskey-api-legacy");
+
+    await runTailscaleSettingsMigration();
+
+    const row = pluginRows.find((entry) => entry.key === "apiKey")!;
+    expect(row.encrypted).toBe(true);
+    expect(row.value).not.toContain("tskey-api-legacy");
+  });
+
+  it("leaves the base URL readable, since it is not a secret", async () => {
+    coreSettings.set("tailscale_api_base_url", "https://headscale.example");
+
+    await runTailscaleSettingsMigration();
+
+    const row = pluginRows.find((entry) => entry.key === "apiBaseUrl")!;
+    expect(row.encrypted).toBe(false);
+  });
+
+  it("removes the legacy rows so no plaintext key is left behind", async () => {
+    coreSettings.set("tailscale_api_key", "tskey-api-legacy");
+    coreSettings.set("tailscale_api_base_url", "https://headscale.example");
+
+    await runTailscaleSettingsMigration();
+
+    expect(coreSettings.has("tailscale_api_key")).toBe(false);
+    expect(coreSettings.has("tailscale_api_base_url")).toBe(false);
+  });
+
+  it("is idempotent: a second run changes nothing", async () => {
+    coreSettings.set("tailscale_api_key", "tskey-api-legacy");
+    coreSettings.set("tailscale_api_base_url", "https://headscale.example");
+
+    await runTailscaleSettingsMigration();
+    const afterFirst = JSON.parse(JSON.stringify(pluginRows));
+
+    const second = await runTailscaleSettingsMigration();
+
+    expect(second.moved).toEqual([]);
+    expect(pluginRows).toEqual(afterFirst);
+  });
+
+  it("cannot double-encrypt the key across runs", async () => {
+    coreSettings.set("tailscale_api_key", "tskey-api-legacy");
+
+    await runTailscaleSettingsMigration();
+    const first = storedValue("apiKey");
+
+    await runTailscaleSettingsMigration();
+
+    expect(storedValue("apiKey")).toBe(first);
+    expect(String(storedValue("apiKey")).match(/sysenc:v1:/g)).toHaveLength(1);
+  });
+
+  it("drops a stale legacy row when the value was already moved", async () => {
+    // An interrupted run, or a downgrade that rewrote the old key.
+    await pluginSettingsRepository.set(
+      "tailscale",
+      "admin",
+      null,
+      "apiKey",
+      JSON.stringify("sysenc:v1:already"),
+      true,
+    );
+    coreSettings.set("tailscale_api_key", "tskey-plaintext-leftover");
+
+    const result = await runTailscaleSettingsMigration();
+
+    expect(result.skipped).toContain("tailscale_api_key");
+    expect(storedValue("apiKey")).toBe("sysenc:v1:already");
+    expect(coreSettings.has("tailscale_api_key")).toBe(false);
+  });
+
+  it("does nothing on a fresh install with no legacy rows", async () => {
+    const result = await runTailscaleSettingsMigration();
+
+    expect(result.moved).toEqual([]);
+    expect(pluginRows).toEqual([]);
+  });
+
+  it("skips an empty legacy value rather than storing one", async () => {
+    coreSettings.set("tailscale_api_key", "");
+
+    const result = await runTailscaleSettingsMigration();
+
+    expect(result.moved).toEqual([]);
+    expect(pluginRows).toEqual([]);
+  });
+
+  it("waits for the plugin row, because of the foreign key", async () => {
+    pluginInstalled = false;
+    coreSettings.set("tailscale_api_key", "tskey-api-legacy");
+
+    const result = await runTailscaleSettingsMigration();
+
+    expect(result.moved).toEqual([]);
+    expect(pluginRows).toEqual([]);
+    // Still there for the next boot, once the plugin is seeded.
+    expect(coreSettings.get("tailscale_api_key")).toBe("tskey-api-legacy");
+  });
+
+  it("moves each key independently", async () => {
+    coreSettings.set("tailscale_api_key", "tskey-api-legacy");
+
+    const result = await runTailscaleSettingsMigration();
+
+    expect(result.moved).toEqual(["tailscale_api_key"]);
+    expect(storedValue("apiBaseUrl")).toBeUndefined();
+  });
+});

src/backend/utils/crypto-migration/tailscale-settings-migration.ts

@@ -0,0 +1,105 @@
+/**
+ * Moves the Tailscale API key and base URL out of core settings.
+ *
+ * Both lived in the core `settings` table, written by a core route that existed
+ * only to serve one plugin. A6 gives plugins their own settings, so they belong
+ * in plugin_settings under the tailscale plugin.
+ *
+ * The key was stored in plaintext, and the route that read it back masked only
+ * its tail while being open to any authenticated user. Landing it as a secret
+ * field encrypts it at rest, so this migration is a fix as much as a move.
+ *
+ * Idempotent in two ways: it stops when a value is already present in the new
+ * home, and encryptSystemSecret returns an already-encrypted value unchanged,
+ * so a second pass can neither duplicate nor double-encrypt.
+ */
+
+import { databaseLogger } from "../logger.js";
+import {
+  createCurrentPluginRepository,
+  createCurrentPluginSettingsRepository,
+  createCurrentSettingsRepository,
+} from "../../database/repositories/factory.js";
+import { encryptSystemSecret } from "../system-secret-crypto.js";
+
+const PLUGIN_ID = "tailscale";
+
+/** Legacy core key -> the field the plugin now declares. */
+const MOVES: { legacyKey: string; field: string; secret: boolean }[] = [
+  { legacyKey: "tailscale_api_key", field: "apiKey", secret: true },
+  { legacyKey: "tailscale_api_base_url", field: "apiBaseUrl", secret: false },
+];
+
+export interface TailscaleSettingsMigrationResult {
+  moved: string[];
+  skipped: string[];
+}
+
+export async function runTailscaleSettingsMigration(): Promise<TailscaleSettingsMigrationResult> {
+  const moved: string[] = [];
+  const skipped: string[] = [];
+
+  try {
+    // The FK to plugins means there is nothing to migrate into until the
+    // plugin has been seeded. Not an error: a build without it just has no
+    // tailscale rows.
+    const plugin = await createCurrentPluginRepository().findById(PLUGIN_ID);
+    if (!plugin) return { moved, skipped };
+
+    const settingsRepository = createCurrentSettingsRepository();
+    const pluginSettingsRepository = createCurrentPluginSettingsRepository();
+
+    for (const move of MOVES) {
+      const legacyValue = await settingsRepository.get(move.legacyKey);
+      if (legacyValue === null || legacyValue === "") {
+        continue;
+      }
+
+      const existing = await pluginSettingsRepository.get(
+        PLUGIN_ID,
+        "admin",
+        null,
+        move.field,
+      );
+      if (existing && existing.value !== null) {
+        // Already moved. Drop the stale copy rather than leaving a plaintext
+        // key behind for a reader that predates this change.
+        await settingsRepository.delete(move.legacyKey);
+        skipped.push(move.legacyKey);
+        continue;
+      }
+
+      const stored = move.secret
+        ? await encryptSystemSecret(legacyValue)
+        : legacyValue;
+
+      await pluginSettingsRepository.set(
+        PLUGIN_ID,
+        "admin",
+        null,
+        move.field,
+        JSON.stringify(stored),
+        move.secret,
+      );
+
+      await settingsRepository.delete(move.legacyKey);
+      moved.push(move.legacyKey);
+    }
+
+    if (moved.length > 0) {
+      databaseLogger.info(
+        `Moved ${moved.length} Tailscale setting(s) into plugin settings`,
+        { operation: "tailscale_settings_migration", moved: moved.join(", ") },
+      );
+    }
+  } catch (error) {
+    // A failed migration must not stop the backend. The plugin falls back to
+    // "no key configured", which is a visible, recoverable state.
+    databaseLogger.warn("Tailscale settings migration failed", {
+      operation: "tailscale_settings_migration",
+      error: error instanceof Error ? error.message : String(error),
+    });
+  }
+
+  return { moved, skipped };
+}

src/types/ui-types.ts

@@ -185,6 +185,8 @@ export type Host = {
   hasTelnetPassword?: boolean;
 
   guacamoleConfig?: GuacamoleConfig;
+  /** Host-scope plugin settings, keyed by plugin id. Secrets are redacted. */
+  pluginSettings?: Record<string, Record<string, unknown>>;
   forceKeyboardInteractive?: boolean;
 
   isShared?: boolean;
@@ -372,8 +374,7 @@ export type AdminSection =
   | "audit-log"
   | "ssl"
   | "plugins"
-  | "touch-input"
-  | "tailscale";
+  | "touch-input";
 export type ThemeId =
   | "dark"
   | "light"

src/ui/AppShell.tsx

@@ -126,14 +126,11 @@ const SessionLogsPanel = lazy(() =>
     default: m.SessionLogsPanel,
   })),
 );
-const UserProfilePanel = lazy(() =>
-  import("@/sidebar/UserProfilePanel").then((m) => ({
-    default: m.UserProfilePanel,
-  })),
-);
-const AdminSettingsPanel = lazy(() =>
-  import("@/sidebar/AdminSettingsPanel").then((m) => ({
-    default: m.AdminSettingsPanel,
+// One screen behind both rail entries. It lazy-loads the profile and admin
+// panels itself, so the shell no longer imports either directly.
+const SettingsScreen = lazy(() =>
+  import("@/settings/SettingsScreen").then((m) => ({
+    default: m.SettingsScreen,
   })),
 );
 const CredentialsPanel = lazy(() =>
@@ -2882,9 +2879,14 @@ export function AppShell({
           </div>
         )}
 
-        {railView === "user-profile" && (
-          <div className="flex-1 min-h-0 overflow-y-auto">
-            <UserProfilePanel
+        {(railView === "user-profile" ||
+          (railView === "admin-settings" && showAdminUI)) && (
+          <div className="flex flex-col flex-1 min-h-0">
+            <SettingsScreen
+              initialSection={
+                railView === "admin-settings" ? "admin" : "profile"
+              }
+              isAdmin={showAdminUI}
               username={username}
               onLogout={onLogout}
               userPrefs={userPrefs}
@@ -2896,13 +2898,6 @@ export function AppShell({
               onRemoteSyncReconnectHandled={() =>
                 setRemoteSyncReconnectRequested(false)
               }
-            />
-          </div>
-        )}
-
-        {railView === "admin-settings" && showAdminUI && (
-          <div className="flex flex-col flex-1 min-h-0 overflow-y-auto">
-            <AdminSettingsPanel
               onEditingChange={setSidebarEditing}
               onOpenHostTab={(host) => {
                 connectHost(host);

src/ui/api/plugins-api.ts

@@ -7,8 +7,153 @@ export interface PluginTabContribution {
   openFrom: string[];
 }
 
+export type PluginSettingsFieldType =
+  | "boolean"
+  | "string"
+  | "number"
+  | "select"
+  | "multiselect"
+  | "secret"
+  | "textarea"
+  | "json"
+  | "custom";
+
+export interface PluginSettingsField {
+  key: string;
+  type: PluginSettingsFieldType;
+  labelKey?: string;
+  descriptionKey?: string;
+  placeholderKey?: string;
+  default?: unknown;
+  options?: { value: string; labelKey: string }[];
+  min?: number;
+  max?: number;
+  requires?: string;
+  permission?: string;
+  group?: string;
+  component?: string;
+}
+
+export interface PluginHostSettingsContribution {
+  enableKey?: string;
+  enableLabelKey?: string;
+  fields: PluginSettingsField[];
+}
+
+export interface PluginSettingsContribution {
+  admin?: PluginSettingsField[];
+  user?: PluginSettingsField[];
+  host?: PluginHostSettingsContribution;
+}
+
 export interface PluginContributions {
   tabs?: PluginTabContribution[];
+  settings?: PluginSettingsContribution;
+}
+
+/** A secret as it arrives from the server. The value never leaves the server. */
+export interface RedactedSecret {
+  set: boolean;
+}
+
+export function isRedactedSecret(value: unknown): value is RedactedSecret {
+  return (
+    typeof value === "object" &&
+    value !== null &&
+    !Array.isArray(value) &&
+    typeof (value as RedactedSecret).set === "boolean"
+  );
+}
+
+export type PluginSettingsValues = Record<string, unknown>;
+
+/** Per-field messages from a rejected PUT, keyed by field key. */
+export interface PluginSettingsErrors {
+  [key: string]: string;
+}
+
+export class PluginSettingsValidationError extends Error {
+  readonly errors: PluginSettingsErrors;
+
+  constructor(errors: PluginSettingsErrors) {
+    super("Some settings were rejected");
+    this.name = "PluginSettingsValidationError";
+    this.errors = errors;
+  }
+}
+
+function settingsPath(pluginId: string, suffix: string): string {
+  return `/plugins/${encodeURIComponent(pluginId)}/settings/${suffix}`;
+}
+
+/** Turns a 400 carrying per-field errors into something a form can render. */
+async function putSettings(
+  path: string,
+  values: PluginSettingsValues,
+): Promise<PluginSettingsValues> {
+  try {
+    const response = await rbacApi.put(path, values);
+    return response.data?.values ?? {};
+  } catch (error) {
+    const data = (
+      error as { response?: { status?: number; data?: { errors?: unknown } } }
+    ).response;
+    if (data?.status === 400 && data.data?.errors) {
+      throw new PluginSettingsValidationError(
+        data.data.errors as PluginSettingsErrors,
+      );
+    }
+    throw error;
+  }
+}
+
+export async function getPluginAdminSettings(
+  pluginId: string,
+): Promise<PluginSettingsValues> {
+  const response = await rbacApi.get(settingsPath(pluginId, "admin"));
+  return response.data?.values ?? {};
+}
+
+export async function updatePluginAdminSettings(
+  pluginId: string,
+  values: PluginSettingsValues,
+): Promise<PluginSettingsValues> {
+  return putSettings(settingsPath(pluginId, "admin"), values);
+}
+
+export async function getPluginUserSettings(
+  pluginId: string,
+): Promise<PluginSettingsValues> {
+  const response = await rbacApi.get(settingsPath(pluginId, "user"));
+  return response.data?.values ?? {};
+}
+
+export async function updatePluginUserSettings(
+  pluginId: string,
+  values: PluginSettingsValues,
+): Promise<PluginSettingsValues> {
+  return putSettings(settingsPath(pluginId, "user"), values);
+}
+
+export async function getPluginHostSettings(
+  pluginId: string,
+  hostId: number,
+): Promise<PluginSettingsValues> {
+  const response = await rbacApi.get(
+    settingsPath(pluginId, `host/${encodeURIComponent(String(hostId))}`),
+  );
+  return response.data?.values ?? {};
+}
+
+export async function updatePluginHostSettings(
+  pluginId: string,
+  hostId: number,
+  values: PluginSettingsValues,
+): Promise<PluginSettingsValues> {
+  return putSettings(
+    settingsPath(pluginId, `host/${encodeURIComponent(String(hostId))}`),
+    values,
+  );
 }
 
 /**
@@ -26,6 +171,8 @@ export interface PluginSummary {
   /** enabled | disabled | blocked | failed, or the loader's live state. */
   state: string;
   contributes: PluginContributions | null;
+  /** Lucide icon name from the manifest. */
+  icon?: string;
 
   tier?: string;
   source?: string;

src/ui/locales/en.json

@@ -3508,7 +3508,6 @@
     "sectionApiKeys": "API Keys",
     "sectionAuditLog": "Audit Log",
     "sectionSsl": "SSL / Let's Encrypt",
-    "sectionTailscale": "Tailscale",
     "sectionTouchInput": "Touch Input",
     "touchEnabled": "Enable Touch Input",
     "touchEnabledDesc": "Allow one-finger touch scrolling in terminals",
@@ -3667,11 +3666,6 @@
     "enableRemoteDesktopDesc": "RDP/VNC remote desktop",
     "enableRemoteDesktopDocsLink": "View docs",
     "guacdUrl": "guacd URL",
-    "tailscaleApiKey": "Tailscale API Key",
-    "tailscaleApiKeyDescription": "Used for device discovery in the host editor. Supports Tailscale (tskey-) and Headscale (hskey-) keys. Generate a key at tailscale.com/admin/settings/keys or from your Headscale instance.",
-    "tailscaleApiKeyDocsLink": "View docs",
-    "tailscaleApiBaseUrl": "API Base URL",
-    "tailscaleApiBaseUrlDescription": "Optional. Point to a self-hosted Headscale instance instead of api.tailscale.com. Leave empty to use the Tailscale default.",
     "oidcDescription": "Configure OpenID Connect for SSO. Fields marked * are required.",
     "oidcDocsLink": "View docs",
     "oidcClientId": "Client ID",
@@ -3822,8 +3816,6 @@
     "remoteDesktopSaved": "Remote Desktop settings saved",
     "remoteDesktopSaveFailed": "Failed to save Remote Desktop settings",
     "remoteDesktopUpdateFailed": "Failed to update Remote Desktop setting",
-    "tailscaleSettingsSaved": "Tailscale settings saved",
-    "tailscaleSettingsSaveFailed": "Failed to save Tailscale settings",
     "logLevelUpdateFailed": "Failed to update log level",
     "oidcSaved": "OIDC configuration saved",
     "oidcSaveFailed": "Failed to save OIDC config",
@@ -5261,7 +5253,52 @@
           "title": "View tailnet devices",
           "description": "See the devices on the connected tailnet."
         }
+      },
+      "settings": {
+        "group": {
+          "api": "Tailscale API",
+          "devices": "Tailnet"
+        },
+        "apiKey": {
+          "label": "API key",
+          "description": "Used to list the devices on your tailnet. Works with a Tailscale or Headscale key.",
+          "placeholder": "tskey-api-... / hskey-api-..."
+        },
+        "apiBaseUrl": {
+          "label": "API base URL",
+          "description": "Leave empty for Tailscale. Set this to point at a Headscale instance.",
+          "placeholder": "https://api.tailscale.com/api/v2"
+        },
+        "devices": {
+          "label": "Device list",
+          "checking": "Checking the tailnet...",
+          "noKey": "No API key set yet.",
+          "error": "Could not reach the tailnet. Check the API key.",
+          "count": "{{count}} device reachable",
+          "count_other": "{{count}} devices reachable",
+          "refresh": "Check"
+        }
       }
     }
+  },
+  "settings": {
+    "title": "Settings",
+    "bandYou": "You",
+    "bandPlugins": "Plugins",
+    "bandInstance": "Instance",
+    "account": "Account",
+    "secretSet": "Set",
+    "secretNotSet": "Not set",
+    "secretReplace": "Replace",
+    "pluginGroupAdmin": "Server settings",
+    "pluginGroupUser": "Your settings",
+    "pluginNoSettings": "{{name}} has no settings you can change.",
+    "pluginStoppedNotice": "{{name}} is installed but not running. These settings are saved but will not take effect.",
+    "pluginSettingsSaved": "Settings saved",
+    "pluginSettingsInvalid": "Some settings could not be saved. Check the highlighted fields.",
+    "pluginSettingsSaveFailed": "Failed to save settings",
+    "pluginSettingsLoadFailed": "Failed to load settings",
+    "pluginsGroupLabel": "Plugins",
+    "hostPluginNotRunning": "{{name}} is installed but not running. These settings are saved but will not take effect."
   }
 }

src/ui/settings/HostPluginSections.tsx

@@ -0,0 +1,140 @@
+/**
+ * Host editor sections contributed by plugins.
+ *
+ * A plugin declares host-scope fields in its manifest and core draws them, so
+ * a plugin cannot ship its own form styling and a section disappears when its
+ * plugin does. The enable switch comes first and gates the rest, which is the
+ * shape the hardcoded feature tabs already have.
+ *
+ * Nothing is rendered when no enabled plugin declares host settings, so the
+ * group does not appear as an empty tab. Phase B fills it as each feature
+ * moves its columns out of ssh_data.
+ */
+
+import { useEffect, useMemo, useState } from "react";
+import { useTranslation } from "react-i18next";
+import { SectionCard } from "@/components/section-card";
+import { PluginIcon } from "@/lib/plugin-icon";
+import { getPlugins, type PluginSummary } from "@/api/plugins-api";
+import { SettingsFieldRow } from "./SettingsFields";
+import { isFieldActive } from "./settings-fields-util";
+
+/** Values for every plugin on one host: { [pluginId]: { [key]: value } }. */
+export type HostPluginSettings = Record<string, Record<string, unknown>>;
+
+/** Enabled plugins declaring host-scope settings. */
+export function usePluginHostSections(): PluginSummary[] {
+  const [plugins, setPlugins] = useState<PluginSummary[]>([]);
+
+  useEffect(() => {
+    let cancelled = false;
+    void getPlugins()
+      .then((loaded) => {
+        if (!cancelled) setPlugins(loaded);
+      })
+      .catch(() => {
+        // Additive: the built-in host tabs do not depend on this.
+      });
+    return () => {
+      cancelled = true;
+    };
+  }, []);
+
+  return useMemo(
+    () =>
+      plugins.filter((plugin) => {
+        if (!plugin.enabled) return false;
+        const host = plugin.contributes?.settings?.host;
+        return !!host && (host.fields.length > 0 || !!host.enableKey);
+      }),
+    [plugins],
+  );
+}
+
+export interface HostPluginSectionsProps {
+  plugins: PluginSummary[];
+  values: HostPluginSettings;
+  setValue: (pluginId: string, key: string, value: unknown) => void;
+}
+
+export function HostPluginSections({
+  plugins,
+  values,
+  setValue,
+}: HostPluginSectionsProps) {
+  if (plugins.length === 0) return null;
+
+  return (
+    <div className="flex flex-col gap-2">
+      {plugins.map((plugin) => (
+        <HostPluginSection
+          key={plugin.id}
+          plugin={plugin}
+          values={values[plugin.id] ?? {}}
+          setValue={(key, value) => setValue(plugin.id, key, value)}
+        />
+      ))}
+    </div>
+  );
+}
+
+function HostPluginSection({
+  plugin,
+  values,
+  setValue,
+}: {
+  plugin: PluginSummary;
+  values: Record<string, unknown>;
+  setValue: (key: string, value: unknown) => void;
+}) {
+  const { t } = useTranslation();
+  const host = plugin.contributes?.settings?.host;
+  if (!host) return null;
+
+  const running = plugin.enabled && plugin.state !== "failed";
+  const enableKey = host.enableKey;
+  // With no enable switch the section is always on, which is what a plugin
+  // declaring only plain fields means.
+  const enabled = enableKey ? values[enableKey] === true : true;
+
+  return (
+    <SectionCard
+      title={plugin.name}
+      icon={<PluginIcon name={plugin.icon} className="size-3.5" />}
+    >
+      {!running && (
+        <div className="my-3 border border-yellow-500/40 bg-yellow-500/10 px-3 py-2 text-xs text-yellow-500">
+          {t("settings.hostPluginNotRunning", { name: plugin.name })}
+        </div>
+      )}
+
+      {enableKey && (
+        <SettingsFieldRow
+          pluginId={plugin.id}
+          field={{
+            key: enableKey,
+            type: "boolean",
+            labelKey: host.enableLabelKey,
+          }}
+          values={values}
+          setValue={setValue}
+          running={running}
+        />
+      )}
+
+      {enabled &&
+        host.fields
+          .filter((field) => isFieldActive(field, values))
+          .map((field) => (
+            <SettingsFieldRow
+              key={field.key}
+              pluginId={plugin.id}
+              field={field}
+              values={values}
+              setValue={setValue}
+              running={running}
+            />
+          ))}
+    </SectionCard>
+  );
+}

src/ui/settings/PluginSettingsPage.tsx

@@ -0,0 +1,238 @@
+/**
+ * One plugin's settings page, drawn from its manifest.
+ *
+ * The plugin declares groups and fields; Termix renders them with the same
+ * SectionCard and SettingRow everything else uses. A plugin cannot ship its
+ * own form styling and drift from the rest of the app, and a page disappears
+ * cleanly when the plugin is uninstalled.
+ */
+
+import { useCallback, useEffect, useMemo, useState } from "react";
+import { useTranslation } from "react-i18next";
+import { Loader2 } from "lucide-react";
+import { toast } from "sonner";
+import { Button } from "@/components/button";
+import { SectionCard } from "@/components/section-card";
+import { pluginKey } from "@/lib/plugin-i18n";
+import { PluginIcon } from "@/lib/plugin-icon";
+import {
+  getPluginAdminSettings,
+  getPluginUserSettings,
+  updatePluginAdminSettings,
+  updatePluginUserSettings,
+  PluginSettingsValidationError,
+  type PluginSettingsErrors,
+  type PluginSettingsField,
+  type PluginSummary,
+} from "@/api/plugins-api";
+import { SettingsFieldRow } from "./SettingsFields";
+import { isFieldActive } from "./settings-fields-util";
+
+interface PluginSettingsPageProps {
+  plugin: PluginSummary;
+  isAdmin: boolean;
+}
+
+type Scope = "admin" | "user";
+
+export function PluginSettingsPage({
+  plugin,
+  isAdmin,
+}: PluginSettingsPageProps) {
+  const { t } = useTranslation();
+  const settings = plugin.contributes?.settings;
+  const running = plugin.enabled && plugin.state !== "failed";
+
+  // Admin fields are not merely disabled for a non-admin: the values behind
+  // them are install-wide configuration they have no business reading.
+  const scopes = useMemo(() => {
+    const entries: { scope: Scope; fields: PluginSettingsField[] }[] = [];
+    if (isAdmin && (settings?.admin?.length ?? 0) > 0) {
+      entries.push({ scope: "admin", fields: settings!.admin! });
+    }
+    if ((settings?.user?.length ?? 0) > 0) {
+      entries.push({ scope: "user", fields: settings!.user! });
+    }
+    return entries;
+  }, [settings, isAdmin]);
+
+  if (scopes.length === 0) {
+    return (
+      <div className="flex flex-col gap-2 p-2.5">
+        <p className="text-xs text-muted-foreground px-1">
+          {t("settings.pluginNoSettings", { name: plugin.name })}
+        </p>
+      </div>
+    );
+  }
+
+  return (
+    <div className="flex flex-col gap-2 p-2.5">
+      {!running && (
+        <div className="border border-yellow-500/40 bg-yellow-500/10 px-3 py-2 text-xs text-yellow-500">
+          {t("settings.pluginStoppedNotice", { name: plugin.name })}
+        </div>
+      )}
+
+      {scopes.map(({ scope, fields }) => (
+        <PluginScopeForm
+          key={scope}
+          plugin={plugin}
+          scope={scope}
+          fields={fields}
+          running={running}
+        />
+      ))}
+    </div>
+  );
+}
+
+/**
+ * One scope's form.
+ *
+ * Admin and user settings are separate requests with separate permissions, so
+ * they save separately rather than sharing one dirty state.
+ */
+function PluginScopeForm({
+  plugin,
+  scope,
+  fields,
+  running,
+}: {
+  plugin: PluginSummary;
+  scope: Scope;
+  fields: PluginSettingsField[];
+  running: boolean;
+}) {
+  const { t } = useTranslation();
+  const [values, setValues] = useState<Record<string, unknown>>({});
+  const [errors, setErrors] = useState<PluginSettingsErrors>({});
+  const [loading, setLoading] = useState(true);
+  const [saving, setSaving] = useState(false);
+  const [dirty, setDirty] = useState(false);
+
+  const load = useCallback(async () => {
+    setLoading(true);
+    try {
+      const loaded =
+        scope === "admin"
+          ? await getPluginAdminSettings(plugin.id)
+          : await getPluginUserSettings(plugin.id);
+      setValues(loaded);
+      setErrors({});
+      setDirty(false);
+    } catch {
+      toast.error(t("settings.pluginSettingsLoadFailed"));
+    } finally {
+      setLoading(false);
+    }
+  }, [plugin.id, scope, t]);
+
+  useEffect(() => {
+    void load();
+  }, [load]);
+
+  const setValue = (key: string, value: unknown) => {
+    setValues((current) => ({ ...current, [key]: value }));
+    setErrors((current) => {
+      if (!current[key]) return current;
+      const next = { ...current };
+      delete next[key];
+      return next;
+    });
+    setDirty(true);
+  };
+
+  const save = async () => {
+    setSaving(true);
+    try {
+      const saved =
+        scope === "admin"
+          ? await updatePluginAdminSettings(plugin.id, values)
+          : await updatePluginUserSettings(plugin.id, values);
+      setValues(saved);
+      setErrors({});
+      setDirty(false);
+      toast.success(t("settings.pluginSettingsSaved"));
+    } catch (error) {
+      if (error instanceof PluginSettingsValidationError) {
+        setErrors(error.errors);
+        toast.error(t("settings.pluginSettingsInvalid"));
+      } else {
+        toast.error(t("settings.pluginSettingsSaveFailed"));
+      }
+    } finally {
+      setSaving(false);
+    }
+  };
+
+  // Fields keep their declared order within a group, and groups appear in the
+  // order their first field does, so a manifest controls the whole layout.
+  const groups = useMemo(() => {
+    const ordered: {
+      key: string | undefined;
+      fields: PluginSettingsField[];
+    }[] = [];
+    for (const field of fields) {
+      const existing = ordered.find((group) => group.key === field.group);
+      if (existing) existing.fields.push(field);
+      else ordered.push({ key: field.group, fields: [field] });
+    }
+    return ordered;
+  }, [fields]);
+
+  if (loading) {
+    return (
+      <div className="flex items-center gap-2 px-1 py-4 text-xs text-muted-foreground">
+        <Loader2 className="size-3.5 animate-spin" />
+        {t("common.loading")}
+      </div>
+    );
+  }
+
+  const icon = <PluginIcon name={plugin.icon} className="size-3.5" />;
+
+  return (
+    <>
+      {groups.map((group, index) => (
+        <SectionCard
+          key={group.key ?? `group-${index}`}
+          title={
+            group.key
+              ? t(pluginKey(plugin.id, group.key))
+              : scope === "admin"
+                ? t("settings.pluginGroupAdmin")
+                : t("settings.pluginGroupUser")
+          }
+          icon={icon}
+        >
+          {group.fields
+            .filter((field) => isFieldActive(field, values))
+            .map((field) => (
+              <SettingsFieldRow
+                key={field.key}
+                pluginId={plugin.id}
+                field={field}
+                values={values}
+                setValue={setValue}
+                running={running}
+                error={errors[field.key]}
+              />
+            ))}
+        </SectionCard>
+      ))}
+
+      <div className="flex justify-end px-1">
+        <Button
+          size="sm"
+          className="h-7 text-xs"
+          disabled={!dirty || saving}
+          onClick={() => void save()}
+        >
+          {saving && <Loader2 className="size-3 animate-spin mr-1.5" />}
+          {t("common.save")}
+        </Button>
+      </div>
+    </>
+  );
+}

src/ui/settings/SettingsFields.tsx

@@ -0,0 +1,294 @@
+/**
+ * One control per declared settings field type.
+ *
+ * A plugin supplies data; core draws the form. That is what keeps every
+ * plugin's settings page looking like the rest of the app, and what makes a
+ * page disappear cleanly when its plugin does.
+ */
+
+import { useTranslation } from "react-i18next";
+import { Input } from "@/components/input";
+import { Textarea } from "@/components/textarea";
+import { Checkbox } from "@/components/checkbox";
+import { PasswordInput } from "@/components/password-input";
+import { Button } from "@/components/button";
+import { FakeSwitch, SettingRow } from "@/components/section-card";
+import {
+  Select,
+  SelectContent,
+  SelectItem,
+  SelectTrigger,
+  SelectValue,
+} from "@/components/select";
+import { pluginKey } from "@/lib/plugin-i18n";
+import { isRedactedSecret, type PluginSettingsField } from "@/api/plugins-api";
+import { getSettingsComponent } from "./settings-components";
+
+export interface SettingsFieldProps {
+  pluginId: string;
+  field: PluginSettingsField;
+  values: Record<string, unknown>;
+  setValue: (key: string, value: unknown) => void;
+  /** Whether the owning plugin is running. */
+  running: boolean;
+  /** Message from a rejected save, shown under the control. */
+  error?: string;
+  disabled?: boolean;
+}
+
+export function SettingsFieldRow({
+  pluginId,
+  field,
+  values,
+  setValue,
+  running,
+  error,
+  disabled = false,
+}: SettingsFieldProps) {
+  const { t } = useTranslation();
+  const label = (key?: string) => (key ? t(pluginKey(pluginId, key)) : "");
+
+  // A custom field draws its own row: it has no single control to put in the
+  // right-hand slot, and often no label of its own either.
+  if (field.type === "custom") {
+    const Component = getSettingsComponent(pluginId, field.component);
+    if (!Component) return null;
+    return (
+      <Component
+        pluginId={pluginId}
+        values={values}
+        setValue={setValue}
+        running={running}
+      />
+    );
+  }
+
+  const value = values[field.key];
+  const readOnly = disabled || !running;
+
+  const description = field.descriptionKey ? (
+    <>
+      {label(field.descriptionKey)}
+      {error && <span className="block text-destructive mt-0.5">{error}</span>}
+    </>
+  ) : error ? (
+    <span className="text-destructive">{error}</span>
+  ) : undefined;
+
+  return (
+    <SettingRow
+      label={label(field.labelKey)}
+      description={description}
+      badge={error ? t("common.error") : undefined}
+    >
+      <FieldControl
+        pluginId={pluginId}
+        field={field}
+        value={value}
+        setValue={setValue}
+        readOnly={readOnly}
+      />
+    </SettingRow>
+  );
+}
+
+function FieldControl({
+  pluginId,
+  field,
+  value,
+  setValue,
+  readOnly,
+}: {
+  pluginId: string;
+  field: PluginSettingsField;
+  value: unknown;
+  setValue: (key: string, value: unknown) => void;
+  readOnly: boolean;
+}) {
+  const { t } = useTranslation();
+  const label = (key?: string) => (key ? t(pluginKey(pluginId, key)) : "");
+  const placeholder = field.placeholderKey
+    ? label(field.placeholderKey)
+    : undefined;
+
+  switch (field.type) {
+    case "boolean":
+      return (
+        <FakeSwitch
+          checked={value === true}
+          disabled={readOnly}
+          onChange={(next) => setValue(field.key, next)}
+        />
+      );
+
+    case "number":
+      return (
+        <Input
+          type="number"
+          className="h-7 w-40 text-sm"
+          disabled={readOnly}
+          min={field.min}
+          max={field.max}
+          placeholder={placeholder}
+          value={value === undefined || value === null ? "" : String(value)}
+          onChange={(event) =>
+            setValue(
+              field.key,
+              event.target.value === "" ? null : Number(event.target.value),
+            )
+          }
+        />
+      );
+
+    case "select":
+      return (
+        <Select
+          disabled={readOnly}
+          value={typeof value === "string" ? value : ""}
+          onValueChange={(next) => setValue(field.key, next)}
+        >
+          <SelectTrigger className="h-7 w-52 text-sm">
+            <SelectValue placeholder={placeholder} />
+          </SelectTrigger>
+          <SelectContent>
+            {(field.options ?? []).map((option) => (
+              <SelectItem key={option.value} value={option.value}>
+                {label(option.labelKey)}
+              </SelectItem>
+            ))}
+          </SelectContent>
+        </Select>
+      );
+
+    case "multiselect": {
+      const selected = Array.isArray(value) ? (value as string[]) : [];
+      return (
+        <div className="flex flex-col gap-1.5 items-end">
+          {(field.options ?? []).map((option) => (
+            <label
+              key={option.value}
+              className="flex items-center gap-2 text-xs text-muted-foreground"
+            >
+              <span>{label(option.labelKey)}</span>
+              <Checkbox
+                disabled={readOnly}
+                checked={selected.includes(option.value)}
+                onCheckedChange={(checked) =>
+                  setValue(
+                    field.key,
+                    checked
+                      ? [...selected, option.value]
+                      : selected.filter((entry) => entry !== option.value),
+                  )
+                }
+              />
+            </label>
+          ))}
+        </div>
+      );
+    }
+
+    case "secret":
+      return (
+        <SecretControl
+          field={field}
+          value={value}
+          setValue={setValue}
+          readOnly={readOnly}
+          placeholder={placeholder}
+        />
+      );
+
+    case "textarea":
+    case "json":
+      return (
+        <Textarea
+          className="w-64 text-sm font-mono min-h-16"
+          disabled={readOnly}
+          placeholder={placeholder}
+          value={
+            typeof value === "string"
+              ? value
+              : value === undefined || value === null
+                ? ""
+                : JSON.stringify(value, null, 2)
+          }
+          onChange={(event) => setValue(field.key, event.target.value)}
+        />
+      );
+
+    default:
+      return (
+        <Input
+          className="h-7 w-52 text-sm"
+          disabled={readOnly}
+          placeholder={placeholder}
+          value={typeof value === "string" ? value : ""}
+          onChange={(event) => setValue(field.key, event.target.value)}
+        />
+      );
+  }
+}
+
+/**
+ * A secret is never sent to the browser, so the control shows whether one is
+ * stored and offers to replace or clear it. Leaving it untouched sends the
+ * redacted marker straight back, which the server reads as "no change".
+ */
+function SecretControl({
+  field,
+  value,
+  setValue,
+  readOnly,
+  placeholder,
+}: {
+  field: PluginSettingsField;
+  value: unknown;
+  setValue: (key: string, value: unknown) => void;
+  readOnly: boolean;
+  placeholder?: string;
+}) {
+  const { t } = useTranslation();
+  const redacted = isRedactedSecret(value);
+  const stored = redacted && value.set;
+
+  if (redacted) {
+    return (
+      <div className="flex items-center gap-2">
+        <span className="text-xs text-muted-foreground">
+          {stored ? t("settings.secretSet") : t("settings.secretNotSet")}
+        </span>
+        <Button
+          variant="outline"
+          size="sm"
+          className="h-7 text-xs"
+          disabled={readOnly}
+          onClick={() => setValue(field.key, "")}
+        >
+          {stored ? t("settings.secretReplace") : t("common.edit")}
+        </Button>
+      </div>
+    );
+  }
+
+  return (
+    <div className="flex items-center gap-2">
+      <PasswordInput
+        className="h-7 w-52 text-sm"
+        disabled={readOnly}
+        placeholder={placeholder}
+        value={typeof value === "string" ? value : ""}
+        onChange={(event) => setValue(field.key, event.target.value)}
+      />
+      <Button
+        variant="ghost"
+        size="sm"
+        className="h-7 text-xs"
+        disabled={readOnly}
+        onClick={() => setValue(field.key, { set: stored })}
+      >
+        {t("common.cancel")}
+      </Button>
+    </div>
+  );
+}

src/ui/settings/SettingsScreen.tsx

@@ -0,0 +1,280 @@
+/**
+ * Everything that configures the app rather than operating a server.
+ *
+ * Profile and admin were two separate rail panels, each a fixed accordion of
+ * hardcoded sections. That is the wrong shape for the number of sections they
+ * hold, and it left no place at all for a plugin to contribute one. This is a
+ * single screen with a banded left nav, and a plugin's page is an entry in it
+ * that appears and disappears with the plugin.
+ *
+ * Both rail buttons still open this, each on its own section, so the Navigation
+ * visibility toggles and the habit of reaching for either one keep working.
+ */
+
+import { lazy, Suspense, useEffect, useMemo, useState } from "react";
+import type { ComponentProps } from "react";
+import { useTranslation } from "react-i18next";
+import {
+  ChevronDown,
+  Puzzle,
+  Settings as SettingsIcon,
+  User,
+} from "lucide-react";
+import { Separator } from "@/components/separator";
+import { PluginIcon } from "@/lib/plugin-icon";
+import { getPlugins, type PluginSummary } from "@/api/plugins-api";
+import { PluginSettingsPage } from "./PluginSettingsPage";
+import { registerLegacySettingsComponents } from "./legacy-settings-components";
+
+const UserProfilePanel = lazy(() =>
+  import("@/sidebar/UserProfilePanel").then((m) => ({
+    default: m.UserProfilePanel,
+  })),
+);
+const AdminSettingsPanel = lazy(() =>
+  import("@/sidebar/AdminSettingsPanel").then((m) => ({
+    default: m.AdminSettingsPanel,
+  })),
+);
+
+// Taken from the panels themselves: this screen only forwards them, so
+// restating their shapes here would be one more thing to keep in step.
+type ProfileProps = ComponentProps<typeof UserProfilePanel>;
+type AdminProps = ComponentProps<typeof AdminSettingsPanel>;
+
+/** Built-in sections, plus "plugin:<id>" for a plugin's own settings page. */
+export type SettingsSectionId = "profile" | "admin" | `plugin:${string}`;
+
+export interface SettingsScreenProps {
+  /** Which page to land on. Both rail entries come in here. */
+  initialSection?: SettingsSectionId;
+  isAdmin?: boolean;
+  /** Forwarded to the profile panel. */
+  username?: ProfileProps["username"];
+  onLogout?: ProfileProps["onLogout"];
+  userPrefs?: ProfileProps["userPrefs"];
+  onPrefsChange?: ProfileProps["onPrefsChange"];
+  remoteSyncInitialServerUrl?: ProfileProps["remoteSyncInitialServerUrl"];
+  remoteSyncReconnectRequested?: ProfileProps["remoteSyncReconnectRequested"];
+  onRemoteSyncReconnectHandled?: ProfileProps["onRemoteSyncReconnectHandled"];
+  /** Forwarded to the admin panel. */
+  onEditingChange?: AdminProps["onEditingChange"];
+  onOpenHostTab?: AdminProps["onOpenHostTab"];
+}
+
+interface NavItem {
+  id: SettingsSectionId;
+  label: string;
+  icon: React.ElementType;
+  iconName?: string;
+}
+
+export function SettingsScreen({
+  initialSection = "profile",
+  isAdmin = false,
+  username,
+  onLogout,
+  userPrefs,
+  onPrefsChange,
+  remoteSyncInitialServerUrl,
+  remoteSyncReconnectRequested,
+  onRemoteSyncReconnectHandled,
+  onEditingChange,
+  onOpenHostTab,
+}: SettingsScreenProps) {
+  const { t } = useTranslation();
+  const [section, setSection] = useState<SettingsSectionId>(initialSection);
+  const [navOpen, setNavOpen] = useState(false);
+  const [plugins, setPlugins] = useState<PluginSummary[]>([]);
+
+  // Registered here rather than at module scope so a custom field's component
+  // exists before any page that renders one. A7 moves this into the loader.
+  useEffect(() => {
+    registerLegacySettingsComponents();
+  }, []);
+
+  useEffect(() => {
+    let cancelled = false;
+    void getPlugins()
+      .then((loaded) => {
+        if (!cancelled) setPlugins(loaded);
+      })
+      .catch(() => {
+        // The plugin band is additive: the core sections still work without it.
+      });
+    return () => {
+      cancelled = true;
+    };
+  }, []);
+
+  // The rail can switch which entry opened the screen while it is mounted.
+  useEffect(() => setSection(initialSection), [initialSection]);
+
+  /**
+   * A plugin gets a page when it is enabled and declares settings this user
+   * could actually change. A non-admin seeing a page of admin-only fields
+   * would be a page they can read and never act on.
+   */
+  const pluginPages = useMemo(
+    () =>
+      plugins.filter((plugin) => {
+        if (!plugin.enabled) return false;
+        const settings = plugin.contributes?.settings;
+        if (!settings) return false;
+        if ((settings.user?.length ?? 0) > 0) return true;
+        return isAdmin && (settings.admin?.length ?? 0) > 0;
+      }),
+    [plugins, isAdmin],
+  );
+
+  const bands = useMemo(() => {
+    const result: { heading: string; items: NavItem[] }[] = [
+      {
+        heading: t("settings.bandYou"),
+        items: [{ id: "profile", label: t("settings.account"), icon: User }],
+      },
+    ];
+
+    if (pluginPages.length > 0) {
+      result.push({
+        heading: t("settings.bandPlugins"),
+        items: pluginPages.map((plugin) => ({
+          id: `plugin:${plugin.id}` as SettingsSectionId,
+          label: plugin.name,
+          icon: Puzzle,
+          iconName: plugin.icon,
+        })),
+      });
+    }
+
+    if (isAdmin) {
+      result.push({
+        heading: t("settings.bandInstance"),
+        items: [{ id: "admin", label: t("nav.admin"), icon: SettingsIcon }],
+      });
+    }
+
+    return result;
+  }, [t, pluginPages, isAdmin]);
+
+  const sections = bands.flatMap((band) => band.items);
+  const active = sections.find((item) => item.id === section) ?? sections[0];
+
+  // A plugin page can vanish under you: the plugin is disabled from the admin
+  // section in the same screen. Fall back rather than render an empty pane.
+  useEffect(() => {
+    if (
+      section.startsWith("plugin:") &&
+      !sections.some((s) => s.id === section)
+    ) {
+      setSection("profile");
+    }
+  }, [section, sections]);
+
+  return (
+    <div className="flex h-full min-h-0 flex-col overflow-hidden bg-background">
+      <header className="flex h-12.5 shrink-0 flex-row items-center border-b border-border">
+        <div className="flex min-w-0 flex-1 items-center gap-2 px-3">
+          <SettingsIcon className="size-4 shrink-0 text-accent-brand" />
+          <span className="truncate text-base font-bold tracking-tight">
+            {t("settings.title")}
+          </span>
+          <Separator orientation="vertical" className="h-4" />
+          <span className="hidden truncate text-[10px] font-semibold uppercase tracking-widest text-muted-foreground md:inline">
+            {active?.label}
+          </span>
+          {/* The nav column does not fit beside the content on a phone, so
+              there it collapses behind the section name. */}
+          <button
+            onClick={() => setNavOpen((open) => !open)}
+            aria-expanded={navOpen}
+            className="flex min-w-0 items-center gap-1 text-[10px] font-semibold uppercase tracking-widest text-muted-foreground md:hidden"
+          >
+            <span className="truncate">{active?.label}</span>
+            <ChevronDown
+              className={`size-3 shrink-0 transition-transform ${navOpen ? "rotate-180" : ""}`}
+            />
+          </button>
+        </div>
+      </header>
+
+      <div className="flex min-h-0 flex-1">
+        <nav
+          className={`${navOpen ? "flex" : "hidden"} w-full shrink-0 flex-col gap-3 overflow-y-auto border-r border-border py-2.5 md:flex md:w-60`}
+        >
+          {bands.map((band) => (
+            <div key={band.heading} className="flex flex-col">
+              <span className="px-2.5 pb-1.5 text-[10px] font-semibold uppercase tracking-widest text-muted-foreground">
+                {band.heading}
+              </span>
+              {band.items.map((item) => {
+                const Icon = item.icon;
+                const on = item.id === section;
+                return (
+                  <button
+                    key={item.id}
+                    onClick={() => {
+                      setSection(item.id);
+                      setNavOpen(false);
+                    }}
+                    className={`flex w-full items-center gap-2 border-l-2 py-2.5 pl-2 pr-2 text-left transition-colors md:py-1.5 ${
+                      on
+                        ? "border-accent-brand bg-accent-brand/10 text-accent-brand"
+                        : "border-transparent text-muted-foreground hover:bg-muted hover:text-foreground"
+                    }`}
+                  >
+                    {item.iconName ? (
+                      <PluginIcon
+                        name={item.iconName}
+                        className="size-3.5 shrink-0"
+                      />
+                    ) : (
+                      <Icon className="size-3.5 shrink-0" />
+                    )}
+                    <span className="truncate text-xs font-medium">
+                      {item.label}
+                    </span>
+                  </button>
+                );
+              })}
+            </div>
+          ))}
+        </nav>
+
+        <div
+          className={`${navOpen ? "hidden" : ""} min-h-0 flex-1 overflow-y-auto md:block`}
+        >
+          <Suspense fallback={null}>
+            {section === "profile" && (
+              <UserProfilePanel
+                username={username}
+                onLogout={onLogout}
+                userPrefs={userPrefs}
+                onPrefsChange={onPrefsChange}
+                remoteSyncInitialServerUrl={remoteSyncInitialServerUrl}
+                remoteSyncReconnectRequested={remoteSyncReconnectRequested}
+                onRemoteSyncReconnectHandled={onRemoteSyncReconnectHandled}
+              />
+            )}
+
+            {section === "admin" && isAdmin && (
+              <AdminSettingsPanel
+                onEditingChange={onEditingChange}
+                onOpenHostTab={onOpenHostTab}
+              />
+            )}
+
+            {section.startsWith("plugin:") &&
+              (() => {
+                const plugin = pluginPages.find(
+                  (candidate) => `plugin:${candidate.id}` === section,
+                );
+                if (!plugin) return null;
+                return <PluginSettingsPage plugin={plugin} isAdmin={isAdmin} />;
+              })()}
+          </Suspense>
+        </div>
+      </div>
+    </div>
+  );
+}

src/ui/settings/components/TailscaleDevicesStatus.tsx

@@ -0,0 +1,90 @@
+/**
+ * The tailnet status shown on the Tailscale settings page.
+ *
+ * Confirms the saved key actually works, which is the question anyone has just
+ * after entering one. Connecting to a device stays in the Tailscale rail panel;
+ * a settings page is for configuring, not for operating.
+ *
+ * Registered by legacy-settings-components.ts until A7 lets the plugin's own
+ * bundle register it.
+ */
+
+import { useCallback, useEffect, useState } from "react";
+import { useTranslation } from "react-i18next";
+import { Loader2, RefreshCw } from "lucide-react";
+import { Button } from "@/components/button";
+import { pluginKey } from "@/lib/plugin-i18n";
+import type { SettingsComponentProps } from "../settings-components";
+import { getTailscaleDevices } from "../../../../plugins/tailscale/src/frontend/tailscale-api";
+
+type Status =
+  | { kind: "loading" }
+  | { kind: "no-key" }
+  | { kind: "error" }
+  | { kind: "ok"; count: number };
+
+export function TailscaleDevicesStatus({ running }: SettingsComponentProps) {
+  const { t } = useTranslation();
+  const [status, setStatus] = useState<Status>({ kind: "loading" });
+
+  const load = useCallback(async () => {
+    if (!running) {
+      setStatus({ kind: "no-key" });
+      return;
+    }
+    setStatus({ kind: "loading" });
+    try {
+      const result = await getTailscaleDevices();
+      if (!result.hasApiKey) {
+        setStatus({ kind: "no-key" });
+        return;
+      }
+      if (result.error) {
+        setStatus({ kind: "error" });
+        return;
+      }
+      setStatus({ kind: "ok", count: result.devices?.length ?? 0 });
+    } catch {
+      setStatus({ kind: "error" });
+    }
+  }, [running]);
+
+  useEffect(() => {
+    void load();
+  }, [load]);
+
+  const label = (key: string) => t(pluginKey("tailscale", key));
+
+  return (
+    <div className="flex items-center justify-between gap-3 py-3">
+      <div className="flex flex-col gap-0.5 min-w-0 flex-1">
+        <span className="text-sm font-medium leading-snug">
+          {label("settings.devices.label")}
+        </span>
+        <span className="text-xs text-muted-foreground leading-snug">
+          {status.kind === "loading" && label("settings.devices.checking")}
+          {status.kind === "no-key" && label("settings.devices.noKey")}
+          {status.kind === "error" && label("settings.devices.error")}
+          {status.kind === "ok" &&
+            t(pluginKey("tailscale", "settings.devices.count"), {
+              count: status.count,
+            })}
+        </span>
+      </div>
+      <Button
+        variant="outline"
+        size="sm"
+        className="h-7 text-xs shrink-0"
+        disabled={!running || status.kind === "loading"}
+        onClick={() => void load()}
+      >
+        {status.kind === "loading" ? (
+          <Loader2 className="size-3 animate-spin" />
+        ) : (
+          <RefreshCw className="size-3" />
+        )}
+        <span className="ml-1.5">{label("settings.devices.refresh")}</span>
+      </Button>
+    </div>
+  );
+}

src/ui/settings/host-plugins-tab.tsx

@@ -0,0 +1,69 @@
+/**
+ * Registers the host editor's "Plugins" tab.
+ *
+ * Goes through the existing registerHostEditorTab seam rather than adding a
+ * case to HostTabId, so the tab genuinely appears and disappears with the
+ * plugins that fill it. Nothing is registered when no enabled plugin declares
+ * host settings, which is what stops an empty tab from showing up.
+ *
+ * Re-run whenever the plugin list changes: enabling a plugin from the settings
+ * screen has to put the tab there without a reload.
+ */
+
+import { Puzzle } from "lucide-react";
+import {
+  registerHostEditorTab,
+  unregisterHostEditorTab,
+} from "@/sidebar/HostManagerTabs";
+import type { PluginSummary } from "@/api/plugins-api";
+import {
+  HostPluginSections,
+  type HostPluginSettings,
+} from "./HostPluginSections";
+
+export const HOST_PLUGINS_TAB_ID = "plugins";
+
+/** Only these two fields are read, so a test can pass a plain object. */
+interface HostFormLike {
+  pluginSettings?: HostPluginSettings;
+}
+
+/**
+ * Adds or removes the tab to match the current plugin list.
+ *
+ * Returns whether the tab is now present, for a caller that needs to redirect
+ * away from it when the last contributor goes.
+ */
+export function syncHostPluginsTab(plugins: PluginSummary[]): boolean {
+  const contributors = plugins.filter((plugin) => {
+    if (!plugin.enabled) return false;
+    const host = plugin.contributes?.settings?.host;
+    return !!host && (host.fields.length > 0 || !!host.enableKey);
+  });
+
+  if (contributors.length === 0) {
+    unregisterHostEditorTab(HOST_PLUGINS_TAB_ID);
+    return false;
+  }
+
+  registerHostEditorTab({
+    id: HOST_PLUGINS_TAB_ID,
+    labelKey: "settings.pluginsGroupLabel",
+    icon: <Puzzle className="size-3" />,
+    component: ({ form, setField }) => (
+      <HostPluginSections
+        plugins={contributors}
+        values={(form as HostFormLike)?.pluginSettings ?? {}}
+        setValue={(pluginId, key, value) => {
+          const current = (form as HostFormLike)?.pluginSettings ?? {};
+          setField("pluginSettings", {
+            ...current,
+            [pluginId]: { ...(current[pluginId] ?? {}), [key]: value },
+          });
+        }}
+      />
+    ),
+  });
+
+  return true;
+}

src/ui/settings/legacy-settings-components.ts

@@ -0,0 +1,27 @@
+/**
+ * Core-side registration of plugin settings components.
+ *
+ * TEMPORARY. A `type: "custom"` settings field names a component the plugin's
+ * own frontend bundle should register through `app.registerSettingsComponent`.
+ * There is no frontend plugin loader yet, so core registers the handful that
+ * exist, the same way pluginLoader.ts mirrors the first-party action
+ * contributions.
+ *
+ * A7 deletes this file. Each plugin registers its own component from its
+ * bundle, and nothing in core names a plugin id.
+ *
+ * Only register what is needed now. Everything else waits for its own step:
+ * the AI providers list stays where it is until B18.
+ */
+
+import { registerSettingsComponent } from "./settings-components.js";
+import { TailscaleDevicesStatus } from "./components/TailscaleDevicesStatus.js";
+
+let registered = false;
+
+export function registerLegacySettingsComponents(): void {
+  if (registered) return;
+  registered = true;
+
+  registerSettingsComponent("tailscale", "devices", TailscaleDevicesStatus);
+}

src/ui/settings/settings-components.ts

@@ -0,0 +1,65 @@
+/**
+ * Components behind a `type: "custom"` settings field.
+ *
+ * Most settings are expressible as a schema, and those are rendered from the
+ * manifest so a plugin cannot ship its own form styling. A few are not: a
+ * device browser, a provider list. Those declare a component id here instead,
+ * which keeps the escape hatch narrow and named rather than letting a plugin
+ * hand core arbitrary markup.
+ *
+ * A7 lets a plugin's own frontend bundle register these through
+ * `app.registerSettingsComponent`. Until then core registers them, in
+ * legacy-settings-components.ts.
+ */
+
+import type { ComponentType } from "react";
+
+export interface SettingsComponentProps {
+  pluginId: string;
+  /** Current values for the scope this field sits in. */
+  values: Record<string, unknown>;
+  /** Writes one key in the same scope. */
+  setValue: (key: string, value: unknown) => void;
+  /** Whether the owning plugin is running. */
+  running: boolean;
+}
+
+export type SettingsComponent = ComponentType<SettingsComponentProps>;
+
+/** Keyed "<pluginId>:<componentId>" so two plugins may use the same name. */
+const registry = new Map<string, SettingsComponent>();
+
+function registryKey(pluginId: string, componentId: string): string {
+  return `${pluginId}:${componentId}`;
+}
+
+export function registerSettingsComponent(
+  pluginId: string,
+  componentId: string,
+  component: SettingsComponent,
+): () => void {
+  const key = registryKey(pluginId, componentId);
+  registry.set(key, component);
+  return () => {
+    if (registry.get(key) === component) registry.delete(key);
+  };
+}
+
+export function getSettingsComponent(
+  pluginId: string,
+  componentId: string | undefined,
+): SettingsComponent | undefined {
+  if (!componentId) return undefined;
+  return registry.get(registryKey(pluginId, componentId));
+}
+
+export function unregisterSettingsComponents(pluginId: string): void {
+  for (const key of [...registry.keys()]) {
+    if (key.startsWith(`${pluginId}:`)) registry.delete(key);
+  }
+}
+
+/** Test helper. */
+export function resetSettingsComponents(): void {
+  registry.clear();
+}

src/ui/settings/settings-fields-util.ts

@@ -0,0 +1,15 @@
+import type { PluginSettingsField } from "@/api/plugins-api";
+
+/**
+ * Whether a field's `requires` gate is satisfied.
+ *
+ * Kept out of the component file so both the settings page and the host editor
+ * section can import it without dragging a component along.
+ */
+export function isFieldActive(
+  field: PluginSettingsField,
+  values: Record<string, unknown>,
+): boolean {
+  if (!field.requires) return true;
+  return values[field.requires] === true;
+}

src/ui/shell/pluginLoader.ts

@@ -19,6 +19,7 @@ import { Bot } from "lucide-react";
 import { unregisterRailItem } from "@/sidebar/rail-items";
 import { unregisterTabComponent } from "@/shell/tabUtils";
 import { getPlugins, type PluginSummary } from "@/api/plugins-api";
+import { syncHostPluginsTab } from "@/settings/host-plugins-tab";
 import {
   declareActionSlot,
   registerAction,
@@ -122,6 +123,10 @@ export function applyPluginState(plugins: PluginSummary[]): void {
   pluginEnabled = nextEnabled;
   disabledTabTypes = nextDisabledTabs;
   applyFirstPartyActions(nextEnabled);
+
+  // The host editor's Plugins tab exists only while something fills it, so it
+  // is re-synced whenever the plugin list changes rather than declared once.
+  syncHostPluginsTab(plugins);
 }
 
 export async function refreshPluginState(): Promise<PluginSummary[]> {

src/ui/sidebar/AdminSettingsPanel.tsx

@@ -64,11 +64,6 @@ import {
   type TerminalImageStorageTestResult,
   type BrandingSettings,
 } from "@/api/settings-api";
-import {
-  getTailscaleSettings,
-  updateTailscaleSettings,
-} from "../../../plugins/tailscale/src/frontend/tailscale-api";
-import { AdminTailscaleSection } from "../../../plugins/tailscale/src/frontend/AdminTailscaleSection";
 import {
   getSessionSharingGloballyEnabled,
   updateSessionSharingGloballyEnabled,
@@ -185,8 +180,6 @@ export function AdminSettingsPanel({
   const [guacEnabled, setGuacEnabled] = useState(false);
   const [guacUrl, setGuacUrl] = useState("guacd:4822");
   const [logLevel, setLogLevel] = useState("info");
-  const [tailscaleApiKey, setTailscaleApiKey] = useState("");
-  const [tailscaleApiBaseUrl, setTailscaleApiBaseUrl] = useState("");
   const [commandHistoryEnabled, setCommandHistoryEnabled] = useState(true);
   const [analyticsEnabled, setAnalyticsEnabled] = useState(true);
   const [analyticsLocked, setAnalyticsLocked] = useState(false);
@@ -413,7 +406,6 @@ export function AdminSettingsPanel({
         guac,
         oidcProv,
         oidcSilent,
-        tailscale,
         cmdHistory,
         analytics,
         sessionSharingEnabled,
@@ -435,7 +427,6 @@ export function AdminSettingsPanel({
         getGuacamoleSettings(),
         getOidcAutoProvision(),
         getOidcSilentLoginDefault(),
-        getTailscaleSettings(),
         getCommandHistoryEnabled(),
         getAnalyticsEnabled(),
         getSessionSharingGloballyEnabled(),
@@ -474,10 +465,6 @@ export function AdminSettingsPanel({
         setGuacEnabled(guac.value.enabled);
         setGuacUrl(guac.value.url || "guacd:4822");
       }
-      if (tailscale.status === "fulfilled") {
-        setTailscaleApiKey(tailscale.value.apiKey ?? "");
-        setTailscaleApiBaseUrl(tailscale.value.apiBaseUrl ?? "");
-      }
       if (cmdHistory.status === "fulfilled") {
         setCommandHistoryEnabled(cmdHistory.value.enabled);
       }
@@ -886,15 +873,6 @@ export function AdminSettingsPanel({
     }
   }
 
-  async function handleSaveTailscaleApiKey() {
-    try {
-      await updateTailscaleSettings(tailscaleApiKey, tailscaleApiBaseUrl);
-      toast.success(t("admin.tailscaleSettingsSaved"));
-    } catch {
-      toast.error(t("admin.tailscaleSettingsSaveFailed"));
-    }
-  }
-
   async function handleSaveLogLevel(level: string) {
     setLogLevel(level);
     try {
@@ -1341,16 +1319,6 @@ export function AdminSettingsPanel({
         handleSaveLogLevel={handleSaveLogLevel}
       />
 
-      <AdminTailscaleSection
-        open={openSections.has("tailscale")}
-        onToggle={() => toggle("tailscale")}
-        tailscaleApiKey={tailscaleApiKey}
-        setTailscaleApiKey={setTailscaleApiKey}
-        tailscaleApiBaseUrl={tailscaleApiBaseUrl}
-        setTailscaleApiBaseUrl={setTailscaleApiBaseUrl}
-        handleSaveTailscaleApiKey={handleSaveTailscaleApiKey}
-      />
-
       <AdminSSOSection
         open={openSections.has("sso")}
         onToggle={() => toggle("sso")}

src/ui/sidebar/HostEditor.tsx

@@ -67,6 +67,7 @@ import {
 import type { Host, VaultProfile } from "@/types/ui-types";
 import type { SSHHost, TunnelStatus } from "@/types";
 import { useTabsSafe } from "@/shell/TabContext";
+import { updatePluginHostSettings } from "@/api/plugins-api";
 import {
   buildHostEditorPayload,
   createHostEditorForm,
@@ -333,6 +334,29 @@ export function HostEditor({
       .finally(() => setTailscaleLoading(false));
   }, [form.authType]);
 
+  /**
+   * Writes each plugin's host-scope values through its own route.
+   *
+   * One request per plugin rather than one per field, and a plugin that
+   * rejects a value is reported without failing the host save that already
+   * succeeded.
+   */
+  const savePluginHostSettings = async (
+    hostId: number,
+    values: Record<string, Record<string, unknown>> | undefined,
+  ) => {
+    if (!values || !Number.isInteger(hostId)) return;
+
+    for (const [pluginId, fields] of Object.entries(values)) {
+      if (!fields || Object.keys(fields).length === 0) continue;
+      try {
+        await updatePluginHostSettings(pluginId, hostId, fields);
+      } catch {
+        toast.error(t("settings.pluginSettingsSaveFailed"));
+      }
+    }
+  };
+
   const handleSave = async () => {
     setSaving(true);
     try {
@@ -350,6 +374,10 @@ export function HostEditor({
           ? await updateSSHHost(Number(host.id), data)
           : await createSSHHost(data);
       }
+      // After the host: a new one has no id to scope settings to until it
+      // exists. A failure here must not claim the host itself failed to save.
+      await savePluginHostSettings(Number(saved.id), form.pluginSettings);
+
       toast.success(host ? t("hosts.hostUpdated") : t("hosts.hostCreated"));
       setPreviewTerminalTheme(null);
       onSave(saved);

src/ui/sidebar/HostEditorData.ts

@@ -342,6 +342,13 @@ export function createHostEditorForm(
       excludedMounts: [] as string[],
       monitoredMounts: [] as Array<{ path: string; label?: string }>,
     },
+
+    // Host-scope plugin settings, keyed by plugin id. Loaded with the host and
+    // saved through the plugin's own scoped route, not in the host payload.
+    pluginSettings: (host?.pluginSettings ?? {}) as Record<
+      string,
+      Record<string, unknown>
+    >,
   };
 }
 

src/ui/tests/settings/SettingsFields.test.tsx

@@ -0,0 +1,297 @@
+/**
+ * The schema-driven settings form.
+ *
+ * A plugin declares fields and core draws them, so the thing worth proving is
+ * that every declared type renders a usable control, reports what the user
+ * typed, and that a secret's value never appears in the DOM.
+ */
+
+import { afterEach, beforeEach, describe, expect, it, vi } from "vitest";
+import { cleanup, fireEvent, render, screen } from "@testing-library/react";
+import type { PluginSettingsField } from "@/api/plugins-api";
+import { SettingsFieldRow } from "@/settings/SettingsFields";
+import { isFieldActive } from "@/settings/settings-fields-util";
+import {
+  registerSettingsComponent,
+  resetSettingsComponents,
+} from "@/settings/settings-components";
+
+vi.mock("react-i18next", () => ({
+  useTranslation: () => ({
+    t: (key: string) => key,
+  }),
+}));
+
+function renderField(
+  field: PluginSettingsField,
+  values: Record<string, unknown> = {},
+  options: { running?: boolean } = {},
+) {
+  const setValue = vi.fn();
+  render(
+    <SettingsFieldRow
+      pluginId="sample"
+      field={field}
+      values={values}
+      setValue={setValue}
+      running={options.running ?? true}
+    />,
+  );
+  return { setValue };
+}
+
+beforeEach(() => {
+  resetSettingsComponents();
+});
+
+afterEach(() => {
+  cleanup();
+});
+
+describe("field types", () => {
+  it("renders a boolean as a switch and reports the toggle", () => {
+    const { setValue } = renderField(
+      { key: "enabled", type: "boolean", labelKey: "enabled.label" },
+      { enabled: false },
+    );
+
+    const toggle = screen.getByRole("button");
+    fireEvent.click(toggle);
+
+    expect(setValue).toHaveBeenCalledWith("enabled", true);
+  });
+
+  it("renders a string as a text box and reports what was typed", () => {
+    const { setValue } = renderField(
+      { key: "baseUrl", type: "string", labelKey: "baseUrl.label" },
+      { baseUrl: "https://a" },
+    );
+
+    const input = screen.getByDisplayValue("https://a");
+    fireEvent.change(input, { target: { value: "https://b" } });
+
+    expect(setValue).toHaveBeenCalledWith("baseUrl", "https://b");
+  });
+
+  it("renders a number with its declared bounds", () => {
+    const { setValue } = renderField(
+      { key: "retries", type: "number", labelKey: "k", min: 0, max: 5 },
+      { retries: 2 },
+    );
+
+    const input = screen.getByDisplayValue("2") as HTMLInputElement;
+    expect(input.getAttribute("min")).toBe("0");
+    expect(input.getAttribute("max")).toBe("5");
+
+    fireEvent.change(input, { target: { value: "4" } });
+    expect(setValue).toHaveBeenCalledWith("retries", 4);
+  });
+
+  it("clears a number to null rather than to zero", () => {
+    const { setValue } = renderField(
+      { key: "retries", type: "number", labelKey: "k" },
+      { retries: 2 },
+    );
+
+    fireEvent.change(screen.getByDisplayValue("2"), { target: { value: "" } });
+
+    expect(setValue).toHaveBeenCalledWith("retries", null);
+  });
+
+  it("renders a textarea", () => {
+    const { setValue } = renderField(
+      { key: "notes", type: "textarea", labelKey: "k" },
+      { notes: "hello" },
+    );
+
+    fireEvent.change(screen.getByDisplayValue("hello"), {
+      target: { value: "goodbye" },
+    });
+
+    expect(setValue).toHaveBeenCalledWith("notes", "goodbye");
+  });
+
+  it("renders json as editable text", () => {
+    renderField({ key: "raw", type: "json", labelKey: "k" }, { raw: { a: 1 } });
+
+    expect(screen.getByDisplayValue(/"a": 1/)).toBeTruthy();
+  });
+
+  it("renders a multiselect option per choice and reports a selection", () => {
+    const { setValue } = renderField(
+      {
+        key: "tags",
+        type: "multiselect",
+        labelKey: "k",
+        options: [
+          { value: "a", labelKey: "opt.a" },
+          { value: "b", labelKey: "opt.b" },
+        ],
+      },
+      { tags: ["a"] },
+    );
+
+    const boxes = screen.getAllByRole("checkbox");
+    expect(boxes).toHaveLength(2);
+
+    fireEvent.click(boxes[1]);
+    expect(setValue).toHaveBeenCalledWith("tags", ["a", "b"]);
+  });
+
+  it("removes a multiselect value when unticked", () => {
+    const { setValue } = renderField(
+      {
+        key: "tags",
+        type: "multiselect",
+        labelKey: "k",
+        options: [
+          { value: "a", labelKey: "opt.a" },
+          { value: "b", labelKey: "opt.b" },
+        ],
+      },
+      { tags: ["a", "b"] },
+    );
+
+    fireEvent.click(screen.getAllByRole("checkbox")[0]);
+
+    expect(setValue).toHaveBeenCalledWith("tags", ["b"]);
+  });
+
+  it("disables every control while the plugin is not running", () => {
+    renderField(
+      { key: "baseUrl", type: "string", labelKey: "k" },
+      { baseUrl: "https://a" },
+      { running: false },
+    );
+
+    expect(
+      (screen.getByDisplayValue("https://a") as HTMLInputElement).disabled,
+    ).toBe(true);
+  });
+});
+
+describe("secrets", () => {
+  const field: PluginSettingsField = {
+    key: "apiKey",
+    type: "secret",
+    labelKey: "apiKey.label",
+  };
+
+  it("shows a stored secret as set, without its value", () => {
+    renderField(field, { apiKey: { set: true } });
+
+    expect(screen.getByText("settings.secretSet")).toBeTruthy();
+    expect(document.body.textContent).not.toContain("tskey");
+  });
+
+  it("shows an unset secret as not set", () => {
+    renderField(field, { apiKey: { set: false } });
+
+    expect(screen.getByText("settings.secretNotSet")).toBeTruthy();
+  });
+
+  it("switches to an input when replacing", () => {
+    const { setValue } = renderField(field, { apiKey: { set: true } });
+
+    fireEvent.click(screen.getByText("settings.secretReplace"));
+
+    expect(setValue).toHaveBeenCalledWith("apiKey", "");
+  });
+
+  it("takes a new value once editing", () => {
+    const { setValue } = renderField(field, { apiKey: "" });
+
+    // A password input has no textbox role, so it is found by its type.
+    const input = document.querySelector(
+      'input[type="password"]',
+    ) as HTMLInputElement;
+    fireEvent.change(input, { target: { value: "tskey-new" } });
+
+    expect(setValue).toHaveBeenCalledWith("apiKey", "tskey-new");
+  });
+
+  it("restores the redacted marker on cancel, so saving changes nothing", () => {
+    const { setValue } = renderField(field, { apiKey: "half-typed" });
+
+    fireEvent.click(screen.getByText("common.cancel"));
+
+    expect(setValue).toHaveBeenCalledWith("apiKey", { set: false });
+  });
+});
+
+describe("custom fields", () => {
+  it("renders a registered component", () => {
+    registerSettingsComponent("sample", "devices", () => (
+      <div>custom-component-here</div>
+    ));
+
+    renderField({ key: "devices", type: "custom", component: "devices" });
+
+    expect(screen.getByText("custom-component-here")).toBeTruthy();
+  });
+
+  it("renders nothing when no component is registered", () => {
+    const { container } = render(
+      <SettingsFieldRow
+        pluginId="sample"
+        field={{ key: "devices", type: "custom", component: "missing" }}
+        values={{}}
+        setValue={vi.fn()}
+        running
+      />,
+    );
+
+    expect(container.innerHTML).toBe("");
+  });
+
+  it("keeps two plugins' components apart", () => {
+    registerSettingsComponent("sample", "shared", () => <div>mine</div>);
+    registerSettingsComponent("other", "shared", () => <div>theirs</div>);
+
+    renderField({ key: "shared", type: "custom", component: "shared" });
+
+    expect(screen.getByText("mine")).toBeTruthy();
+    expect(screen.queryByText("theirs")).toBeNull();
+  });
+});
+
+describe("errors", () => {
+  it("shows a per-field message from a rejected save", () => {
+    render(
+      <SettingsFieldRow
+        pluginId="sample"
+        field={{ key: "retries", type: "number", labelKey: "k" }}
+        values={{ retries: 99 }}
+        setValue={vi.fn()}
+        running
+        error='"retries" must be at most 5'
+      />,
+    );
+
+    expect(screen.getByText('"retries" must be at most 5')).toBeTruthy();
+  });
+});
+
+describe("isFieldActive", () => {
+  const gated: PluginSettingsField = {
+    key: "socketPath",
+    type: "string",
+    labelKey: "k",
+    requires: "enableDocker",
+  };
+
+  it("is inactive while the named boolean is off", () => {
+    expect(isFieldActive(gated, { enableDocker: false })).toBe(false);
+    expect(isFieldActive(gated, {})).toBe(false);
+  });
+
+  it("is active once the named boolean is on", () => {
+    expect(isFieldActive(gated, { enableDocker: true })).toBe(true);
+  });
+
+  it("is always active without a requires", () => {
+    expect(isFieldActive({ key: "a", type: "string", labelKey: "k" }, {})).toBe(
+      true,
+    );
+  });
+});

src/ui/tests/settings/SettingsScreen.test.tsx

@@ -0,0 +1,185 @@
+/**
+ * The one Settings screen.
+ *
+ * What matters here is the navigation: which bands appear for whom, that a
+ * plugin's page shows up only when it has settings that user could change, and
+ * that the nav collapses rather than disappearing on a phone.
+ */
+
+import { afterEach, beforeEach, describe, expect, it, vi } from "vitest";
+import { cleanup, render, screen, waitFor } from "@testing-library/react";
+import type { PluginSummary } from "@/api/plugins-api";
+
+const { getPluginsMock } = vi.hoisted(() => ({ getPluginsMock: vi.fn() }));
+
+vi.mock("@/api/plugins-api", async (importOriginal) => ({
+  ...(await importOriginal<typeof import("@/api/plugins-api")>()),
+  getPlugins: getPluginsMock,
+}));
+
+vi.mock("react-i18next", () => ({
+  useTranslation: () => ({ t: (key: string) => key }),
+}));
+
+// The two core panels are large and pull in most of the app; this screen only
+// has to decide which one to mount.
+vi.mock("@/sidebar/UserProfilePanel", () => ({
+  UserProfilePanel: () => <div>profile-panel</div>,
+}));
+vi.mock("@/sidebar/AdminSettingsPanel", () => ({
+  AdminSettingsPanel: () => <div>admin-panel</div>,
+}));
+vi.mock("@/settings/legacy-settings-components", () => ({
+  registerLegacySettingsComponents: vi.fn(),
+}));
+
+const { SettingsScreen } = await import("@/settings/SettingsScreen");
+
+function plugin(overrides: Partial<PluginSummary> = {}): PluginSummary {
+  return {
+    id: "tailscale",
+    name: "Tailscale",
+    version: "1.0.0",
+    enabled: true,
+    state: "active",
+    contributes: {
+      settings: { admin: [{ key: "apiKey", type: "secret", labelKey: "k" }] },
+    },
+    ...overrides,
+  } as PluginSummary;
+}
+
+beforeEach(() => {
+  getPluginsMock.mockReset();
+  getPluginsMock.mockResolvedValue([]);
+});
+
+afterEach(() => {
+  cleanup();
+});
+
+describe("navigation bands", () => {
+  it("always shows the You band", async () => {
+    render(<SettingsScreen />);
+
+    expect(await screen.findByText("settings.bandYou")).toBeTruthy();
+  });
+
+  it("shows the Instance band only to an admin", async () => {
+    const { unmount } = render(<SettingsScreen isAdmin={false} />);
+    await waitFor(() => expect(getPluginsMock).toHaveBeenCalled());
+    expect(screen.queryByText("settings.bandInstance")).toBeNull();
+    unmount();
+
+    render(<SettingsScreen isAdmin />);
+    expect(await screen.findByText("settings.bandInstance")).toBeTruthy();
+  });
+
+  it("shows no Plugins band when nothing declares settings", async () => {
+    render(<SettingsScreen isAdmin />);
+    await waitFor(() => expect(getPluginsMock).toHaveBeenCalled());
+
+    expect(screen.queryByText("settings.bandPlugins")).toBeNull();
+  });
+
+  it("lists a plugin with admin settings for an admin", async () => {
+    getPluginsMock.mockResolvedValue([plugin()]);
+
+    render(<SettingsScreen isAdmin />);
+
+    expect(await screen.findByText("settings.bandPlugins")).toBeTruthy();
+    expect(screen.getByText("Tailscale")).toBeTruthy();
+  });
+
+  it("hides an admin-only plugin page from a non-admin", async () => {
+    getPluginsMock.mockResolvedValue([plugin()]);
+
+    render(<SettingsScreen isAdmin={false} />);
+    await waitFor(() => expect(getPluginsMock).toHaveBeenCalled());
+
+    expect(screen.queryByText("Tailscale")).toBeNull();
+  });
+
+  it("shows a plugin with user settings to everyone", async () => {
+    getPluginsMock.mockResolvedValue([
+      plugin({
+        contributes: {
+          settings: { user: [{ key: "theme", type: "string", labelKey: "k" }] },
+        },
+      }),
+    ]);
+
+    render(<SettingsScreen isAdmin={false} />);
+
+    expect(await screen.findByText("Tailscale")).toBeTruthy();
+  });
+
+  it("hides a disabled plugin's page", async () => {
+    getPluginsMock.mockResolvedValue([plugin({ enabled: false })]);
+
+    render(<SettingsScreen isAdmin />);
+    await waitFor(() => expect(getPluginsMock).toHaveBeenCalled());
+
+    expect(screen.queryByText("Tailscale")).toBeNull();
+  });
+
+  it("keeps working when the plugin list cannot be loaded", async () => {
+    getPluginsMock.mockRejectedValue(new Error("offline"));
+
+    render(<SettingsScreen isAdmin />);
+
+    expect(await screen.findByText("settings.bandYou")).toBeTruthy();
+  });
+});
+
+describe("initial section", () => {
+  it("lands on the profile panel by default", async () => {
+    render(<SettingsScreen />);
+
+    expect(await screen.findByText("profile-panel")).toBeTruthy();
+  });
+
+  it("lands on the admin panel when opened from the admin rail entry", async () => {
+    render(<SettingsScreen isAdmin initialSection="admin" />);
+
+    expect(await screen.findByText("admin-panel")).toBeTruthy();
+  });
+
+  it("does not mount the admin panel for a non-admin", async () => {
+    render(<SettingsScreen isAdmin={false} initialSection="admin" />);
+    await waitFor(() => expect(getPluginsMock).toHaveBeenCalled());
+
+    expect(screen.queryByText("admin-panel")).toBeNull();
+  });
+
+  it("switches section when the rail entry changes", async () => {
+    const { rerender } = render(
+      <SettingsScreen isAdmin initialSection="profile" />,
+    );
+    expect(await screen.findByText("profile-panel")).toBeTruthy();
+
+    rerender(<SettingsScreen isAdmin initialSection="admin" />);
+
+    expect(await screen.findByText("admin-panel")).toBeTruthy();
+  });
+});
+
+describe("phone layout", () => {
+  it("offers a disclosure button for the collapsed nav", async () => {
+    render(<SettingsScreen />);
+    await screen.findByText("settings.bandYou");
+
+    const toggle = document.querySelector("button[aria-expanded]");
+    expect(toggle).toBeTruthy();
+    expect(toggle?.getAttribute("aria-expanded")).toBe("false");
+  });
+
+  it("hides the nav below md and shows it from md up", async () => {
+    render(<SettingsScreen />);
+    await screen.findByText("settings.bandYou");
+
+    const nav = document.querySelector("nav")!;
+    expect(nav.className).toContain("hidden");
+    expect(nav.className).toContain("md:flex");
+  });
+});

src/ui/tests/settings/host-plugins-tab.test.tsx

@@ -0,0 +1,193 @@
+/**
+ * The host editor's Plugins group.
+ *
+ * No bundled plugin declares host settings yet, so a fixture stands in for one.
+ * The rule worth protecting is the empty case: with nothing to show, the tab
+ * must not be registered at all rather than appearing blank.
+ */
+
+import { afterEach, beforeEach, describe, expect, it, vi } from "vitest";
+import { cleanup, fireEvent, render, screen } from "@testing-library/react";
+import type { PluginSummary } from "@/api/plugins-api";
+import {
+  HOST_PLUGINS_TAB_ID,
+  syncHostPluginsTab,
+} from "@/settings/host-plugins-tab";
+import {
+  getRegisteredHostEditorTab,
+  unregisterHostEditorTab,
+} from "@/sidebar/HostManagerTabs";
+import { HostPluginSections } from "@/settings/HostPluginSections";
+
+vi.mock("react-i18next", () => ({
+  useTranslation: () => ({ t: (key: string) => key }),
+}));
+
+function plugin(overrides: Partial<PluginSummary> = {}): PluginSummary {
+  return {
+    id: "docker",
+    name: "Docker",
+    version: "1.0.0",
+    enabled: true,
+    state: "active",
+    icon: "Box",
+    contributes: {
+      settings: {
+        host: {
+          enableKey: "enableDocker",
+          enableLabelKey: "enableDocker.label",
+          fields: [
+            { key: "socketPath", type: "string", labelKey: "socket.label" },
+          ],
+        },
+      },
+    },
+    ...overrides,
+  } as PluginSummary;
+}
+
+beforeEach(() => {
+  unregisterHostEditorTab(HOST_PLUGINS_TAB_ID);
+});
+
+afterEach(() => {
+  cleanup();
+  unregisterHostEditorTab(HOST_PLUGINS_TAB_ID);
+});
+
+describe("syncHostPluginsTab", () => {
+  it("registers the tab when a plugin contributes host settings", () => {
+    expect(syncHostPluginsTab([plugin()])).toBe(true);
+    expect(getRegisteredHostEditorTab(HOST_PLUGINS_TAB_ID)).toBeDefined();
+  });
+
+  it("registers nothing when no plugin contributes", () => {
+    expect(syncHostPluginsTab([])).toBe(false);
+    expect(getRegisteredHostEditorTab(HOST_PLUGINS_TAB_ID)).toBeUndefined();
+  });
+
+  it("ignores a plugin with no host settings", () => {
+    const other = plugin({
+      id: "ai",
+      contributes: { settings: { admin: [] } },
+    });
+
+    expect(syncHostPluginsTab([other])).toBe(false);
+  });
+
+  it("ignores a disabled plugin", () => {
+    expect(syncHostPluginsTab([plugin({ enabled: false })])).toBe(false);
+  });
+
+  it("removes the tab once the last contributor goes", () => {
+    syncHostPluginsTab([plugin()]);
+    expect(getRegisteredHostEditorTab(HOST_PLUGINS_TAB_ID)).toBeDefined();
+
+    syncHostPluginsTab([plugin({ enabled: false })]);
+
+    expect(getRegisteredHostEditorTab(HOST_PLUGINS_TAB_ID)).toBeUndefined();
+  });
+
+  it("registers for a plugin declaring only an enable switch", () => {
+    const bare = plugin({
+      contributes: {
+        settings: {
+          host: { enableKey: "enableThing", enableLabelKey: "k", fields: [] },
+        },
+      },
+    });
+
+    expect(syncHostPluginsTab([bare])).toBe(true);
+  });
+});
+
+describe("HostPluginSections", () => {
+  it("shows the enable switch and hides the fields until it is on", () => {
+    const setValue = vi.fn();
+    render(
+      <HostPluginSections
+        plugins={[plugin()]}
+        values={{ docker: { enableDocker: false } }}
+        setValue={setValue}
+      />,
+    );
+
+    expect(screen.getByText("plugins.docker.enableDocker.label")).toBeTruthy();
+    expect(screen.queryByText("plugins.docker.socket.label")).toBeNull();
+  });
+
+  it("shows the fields once the enable switch is on", () => {
+    render(
+      <HostPluginSections
+        plugins={[plugin()]}
+        values={{ docker: { enableDocker: true } }}
+        setValue={vi.fn()}
+      />,
+    );
+
+    expect(screen.getByText("plugins.docker.socket.label")).toBeTruthy();
+  });
+
+  it("reports a change against the right plugin", () => {
+    const setValue = vi.fn();
+    render(
+      <HostPluginSections
+        plugins={[plugin()]}
+        values={{ docker: { enableDocker: false } }}
+        setValue={setValue}
+      />,
+    );
+
+    fireEvent.click(screen.getAllByRole("button")[0]);
+
+    expect(setValue).toHaveBeenCalledWith("docker", "enableDocker", true);
+  });
+
+  it("warns when the plugin is installed but not running", () => {
+    render(
+      <HostPluginSections
+        plugins={[plugin({ state: "failed" })]}
+        values={{ docker: {} }}
+        setValue={vi.fn()}
+      />,
+    );
+
+    expect(screen.getByText("settings.hostPluginNotRunning")).toBeTruthy();
+  });
+
+  it("renders nothing at all with no contributing plugins", () => {
+    const { container } = render(
+      <HostPluginSections plugins={[]} values={{}} setValue={vi.fn()} />,
+    );
+
+    expect(container.innerHTML).toBe("");
+  });
+
+  it("keeps two plugins' values apart", () => {
+    const vault = plugin({
+      id: "vault",
+      name: "Vault",
+      contributes: {
+        settings: {
+          host: {
+            fields: [{ key: "role", type: "string", labelKey: "role.label" }],
+          },
+        },
+      },
+    });
+
+    render(
+      <HostPluginSections
+        plugins={[plugin(), vault]}
+        values={{
+          docker: { enableDocker: true, socketPath: "/var/run/docker.sock" },
+          vault: { role: "web" },
+        }}
+        setValue={vi.fn()}
+      />,
+    );
+
+    expect(screen.getByDisplayValue("/var/run/docker.sock")).toBeTruthy();
+    expect(screen.getByDisplayValue("web")).toBeTruthy();
+  });
+});