permissions: a plugin can mark part of its surface owner-only

A plugin worth granting to a Member can also hold the credential the rest of it runs on. Jellyfin's
/_config stores a server's admin token and drives account provisioning; the rest of the plugin is
exactly what a Member should have. The choice was all of it or none of it.

`ownerOnly` on a plugin permission takes sub-paths relative to the mount prefix. The permission stays
fully grantable — this is not the ownerOnly PERMISSION that manifest.ts refuses, and that refusal
still stands: a permission nobody can delegate is a contradiction. This says a few paths administer
the plugin rather than use it.

Declared by the plugin, enforced by the platform. A plugin could check this itself and the first one
would; the tenth would add a route and forget, with no boot failure and no warning — the shape
assertPermissionTotality exists to prevent. In the gate it is enforced once, on the door they all
pass through, and a route added later by someone who never read the manifest is covered by default.

Checked before selfService and before kind. A path that is somehow both self-service and owner-only
is a contradiction, and the safe reading has to win. A write grant does not unlock it either — level
is not the question this answers.

Also forwards X-Officer-Owner and X-Officer-Level to a sidecar whose proxy names its permission key,
for the finer decisions the platform cannot make for it: whose rows a read returns, which fields a
level may see. Facts, never the role name — a plugin branching on "Super Admin" would give every
plugin repository an opinion about the platform's role vocabulary, and renaming a role would change
authorization in code the platform does not own. These are safe to trust only because the proxy
copies a three-item allowlist off the inbound request; that is now written where it would be changed.

The owner's level is reported as write rather than the absent 'none': they hold everything implicitly
and appear in no grants map, so the raw lookup inverts the meaning for the one account that can do
anything.

No plugin declares one yet. Jellyfin cannot until connections stop being per-user — locking /_config
today leaves a Member with a plugin that only shows a connect form they may not submit.

Co-Authored-By: Claude Opus 5 <noreply@anthropic.com>

src/servers/permissions/authorize.ts

@@ -6,6 +6,7 @@ import {
   permissionForApiPath,
   permissionForWsProvider,
   isRequestAllowedAtLevel,
+  isOwnerOnlyRoute,
   isSelfServiceRoute,
   type PermissionLevel,
 } from './registry';
@@ -131,6 +132,13 @@ export async function isApiRequestAllowed(
   // a 403 on a route that does not exist is not a leak, and a permissive default here would be.
   if (!permission) return { allowed: false, reason: 'no permission covers this path' };
 
+  // BEFORE self-service, and before kind. A permission can be fully granted and still have an
+  // administrative corner — a plugin's settings, holding the credential the rest of it runs on. The owner
+  // already returned above, so reaching here at all means this is not them.
+  if (isOwnerOnlyRoute(permission, path)) {
+    return { allowed: false, reason: `that part of ${permission.label} is restricted to the server owner` };
+  }
+
   // Checked before kind, because a self-service route acts on the caller and is therefore not the thing
   // the permission around it restricts. Exact method and path only — see the field's comment.
   if (isSelfServiceRoute(permission, method, path)) return { allowed: true };

src/servers/permissions/registry.test.ts

@@ -8,6 +8,7 @@ import {
   permissionForWsProvider,
   isRequestAllowedAtLevel,
   isSelfServiceRoute,
+  isOwnerOnlyRoute,
 } from './registry';
 import { assertPermissionTotality, isExemptApiPath } from './totality';
 
@@ -298,3 +299,67 @@ test('notify: a read-level member can register and deregister their own device',
   // Still scoped: read level does not become write level for the rest of the surface.
   expect(isRequestAllowedAtLevel(notify!, 'read', 'POST', '/api/notify/_officer/notify')).toBe(false);
 });
+
+// ── ownerOnly: the administrative corner of a shareable surface ──
+//
+// The case: a plugin worth granting to a Member that also holds the credential everything else runs on.
+// Jellyfin's `/_config` stores a server's admin token and drives account provisioning; the rest of the
+// plugin is exactly what a Member should have. Before this the choice was all of it or none.
+//
+// The owner never reaches any of this — `isApiRequestAllowed` returns for them before the permission is
+// even resolved — so every case here is about somebody who legitimately holds the permission.
+
+const withOwnerOnly: Permission = {
+  key: 'jellyfin',
+  label: 'Jellyfin',
+  description: 'films and shows',
+  kind: 'app',
+  api: ['/jellyfin'],
+  ownerOnly: ['/_config'],
+  personal: ['/_officer'],
+  selfService: ['POST /_config/ping'],
+};
+
+describe('isOwnerOnlyRoute', () => {
+  test('matches the declared sub-path', () => {
+    expect(isOwnerOnlyRoute(withOwnerOnly, '/api/jellyfin/_config')).toBe(true);
+  });
+
+  test('matches everything under it — a settings surface is a tree, not a list of leaves', () => {
+    expect(isOwnerOnlyRoute(withOwnerOnly, '/api/jellyfin/_config/3/users')).toBe(true);
+    expect(isOwnerOnlyRoute(withOwnerOnly, '/api/jellyfin/_config/3/activate')).toBe(true);
+  });
+
+  test('leaves the rest of the plugin alone', () => {
+    expect(isOwnerOnlyRoute(withOwnerOnly, '/api/jellyfin/_jf/Items')).toBe(false);
+    expect(isOwnerOnlyRoute(withOwnerOnly, '/api/jellyfin')).toBe(false);
+  });
+
+  test('does not match a path that merely starts with the same letters', () => {
+    // `/_configuration` is a different route. Prefix matching that ignored the boundary would silently
+    // lock a route nobody declared, which is the mirror of the bug this feature exists to prevent.
+    expect(isOwnerOnlyRoute(withOwnerOnly, '/api/jellyfin/_configuration')).toBe(false);
+  });
+
+  test('does not reach outside the permission that declared it', () => {
+    expect(isOwnerOnlyRoute(withOwnerOnly, '/api/music/_config')).toBe(false);
+  });
+
+  test('a permission declaring none is unaffected', () => {
+    expect(isOwnerOnlyRoute({ ...withOwnerOnly, ownerOnly: undefined }, '/api/jellyfin/_config')).toBe(false);
+  });
+
+  // The two rules that could contradict each other, and which way it has to fall. `authorize.ts` checks
+  // ownerOnly FIRST, so these assertions are about the matchers agreeing that the overlap exists — the
+  // precedence is what makes it safe.
+  test('overlapping selfService does not unlock it', () => {
+    expect(isSelfServiceRoute(withOwnerOnly, 'POST', '/api/jellyfin/_config/ping')).toBe(true);
+    expect(isOwnerOnlyRoute(withOwnerOnly, '/api/jellyfin/_config/ping')).toBe(true);
+  });
+
+  test('a write grant does not unlock it either', () => {
+    // `isRequestAllowedAtLevel` says yes, because level is not the question ownerOnly answers.
+    expect(isRequestAllowedAtLevel(withOwnerOnly, 'write', 'POST', '/api/jellyfin/_config')).toBe(true);
+    expect(isOwnerOnlyRoute(withOwnerOnly, '/api/jellyfin/_config')).toBe(true);
+  });
+});

src/servers/permissions/registry.ts

@@ -83,6 +83,33 @@ export type Permission = {
    * permission permits `POST /api/notify/devices/123`.
    */
   personal?: string[];
+  /**
+   * Sub-paths, relative to each `api` prefix, that ONLY the owner may reach — at any level, by any
+   * method, however the permission is granted.
+   *
+   * For the administrative corner of an otherwise shareable surface. Jellyfin is the case: the plugin is
+   * exactly what a Member should have, and `/_config` — which stores a server's admin token and drives
+   * account provisioning — is exactly what they should not. Without this the only options were to grant
+   * the whole plugin or none of it.
+   *
+   * ── Why this is not a kind, and not `ownerOnly` on a permission ──
+   *
+   * `plugins/manifest.ts` refuses an `ownerOnly` PERMISSION, and that refusal still stands: a permission
+   * is a thing the owner delegates, and one nobody can delegate is a contradiction. This is narrower and
+   * different in kind — the permission stays fully grantable, and a few paths inside it are marked as
+   * administering the plugin rather than using it.
+   *
+   * ── Why it is declared here rather than enforced by each plugin ──
+   *
+   * A plugin could check this itself, and the first one would. The tenth would forget a route and nothing
+   * would notice — no boot failure, no warning, no test, exactly the shape `assertPermissionTotality`
+   * exists to prevent. Declared here it is enforced once, for every plugin, on the door they all pass
+   * through, and a route added later by someone who never read this is covered by default.
+   *
+   * Beaten by nothing. Checked before `selfService`, so a path that is somehow both is owner-only —
+   * fail closed, since the two together are a contradiction and the safe reading has to win.
+   */
+  ownerOnly?: string[];
   /**
    * Reads that must stay POST — see the note at the top. A read grant permits these paths at any method.
    * Written relative to the permission's `api` prefix, like `personal`.
@@ -497,6 +524,22 @@ export function permissionForWsProvider(provider: string): Permission | null {
   return PERMISSIONS.find((c) => c.ws?.includes(provider)) ?? null;
 }
 
+/**
+ * Is this path inside one of the permission's owner-only sub-paths?
+ *
+ * Prefix-matched, like `personal` — `/_config` covers `/_config/3/users`. A settings surface is a tree,
+ * and enumerating its leaves is how one gets missed.
+ */
+export function isOwnerOnlyRoute(permission: Permission, path: string): boolean {
+  if (!permission.ownerOnly?.length) return false;
+  const rest = path.startsWith('/api') ? path.slice('/api'.length) : path;
+  return permission.api.some((prefix) => {
+    if (!isPrefixOf(prefix, rest)) return false;
+    const sub = rest.slice(prefix.length) || '/';
+    return permission.ownerOnly!.some((entry) => isPrefixOf(entry, sub));
+  });
+}
+
 /**
  * Is this an exact self-service route — one any authenticated account may call without holding the
  * permission at all? Matched exactly on method AND path, never as a prefix.

src/servers/plugins/manifest.ts

@@ -46,6 +46,26 @@ export type PluginPermission = {
    * broken feature where a withheld permission should be.
    */
   readOnlyWrites?: string[];
+  /**
+   * Sub-paths, relative to the plugin's mount prefix, that ONLY the owner may reach — at any granted
+   * level, by any method.
+   *
+   * For the administrative corner of a surface that is otherwise worth sharing. Jellyfin's `/_config`
+   * stores a server's admin token and drives account provisioning; the rest of the plugin is exactly what
+   * a Member should have. Without this the choice was the whole plugin or none of it.
+   *
+   * Note what this is NOT. It does not make the PERMISSION owner-only — see the comment above, which
+   * still stands: a permission nobody can delegate is a contradiction. The permission stays fully
+   * grantable and these few paths are marked as administering the plugin rather than using it.
+   *
+   * DECLARED here, ENFORCED by the platform's permission gate. The plugin knows which of its paths are
+   * settings; the platform is the thing that cannot forget to check. A plugin doing this itself would
+   * work until the tenth one added a route and did not, with no boot failure and no warning — the shape
+   * `assertPermissionTotality` exists to prevent.
+   *
+   * Prefix-matched: `/_config` covers `/_config/3/users`.
+   */
+  ownerOnly?: string[];
 };
 
 /** The package managers the platform knows how to drive. Mirrors `PM` in machine-setup's lib/base.sh. */
@@ -542,6 +562,15 @@ export function manifestProblems(appName: string, manifest: Partial<PluginManife
       if (typeof permission.label !== 'string' || !permission.label) {
         problems.push(`permissions[${i}].label is required`);
       }
+      // A leading slash is not cosmetic: these are matched against the path left after the plugin's own
+      // prefix is stripped, which always starts with one. `_config` would match nothing and would do it
+      // silently — an owner-only route that is quietly reachable by everyone is the worst possible way to
+      // get this wrong, so it is a manifest error rather than a surprise.
+      for (const [j, sub] of (permission.ownerOnly ?? []).entries()) {
+        if (typeof sub !== 'string' || !sub.startsWith('/')) {
+          problems.push(`permissions[${i}].ownerOnly[${j}] must be a path starting with "/"`);
+        }
+      }
     }
   }
   problems.push(...osDependencyProblems(manifest.osDependencies));

src/servers/plugins/mount.ts

@@ -139,6 +139,10 @@ function pluginPermissions(state: PluginState): Permission[] {
     api: index === 0 ? [prefix] : [],
     routes: index === 0 ? [prefix] : [],
     ...(permission.readOnlyWrites ? { readOnlyWrites: permission.readOnlyWrites } : {}),
+    // Only meaningful on the entry that claims the paths — a later permission claims no `api`, so an
+    // `ownerOnly` on it would match nothing. Threaded anyway rather than dropped: silently ignoring a
+    // declaration is how a plugin author concludes the field does not work.
+    ...(permission.ownerOnly ? { ownerOnly: permission.ownerOnly } : {}),
   }));
 }
 

src/servers/sidecar/create-proxy.ts

@@ -2,6 +2,7 @@ import type { Hono } from 'hono';
 import type { HonoVariables } from '../create-router';
 import { createRouter } from '../create-router';
 import * as sidecar from '../sidecar-registry';
+import { getEffectivePermissions } from '../permissions/authorize';
 import { registerProxiedPrefix } from './proxied-prefixes';
 
 // The shared auth-and-forward proxy every HTTP sidecar needs.
@@ -52,6 +53,16 @@ export type SidecarProxyParams = {
    * only loses its ERROR MESSAGE — one Immich accepts is read to the end and never races at all.
    */
   bufferRequestBody?: boolean;
+  /**
+   * The permission key gating this sidecar, when one does. Adds `X-Officer-Owner` and `X-Officer-Level`
+   * to what is forwarded, so the sidecar can make the finer decisions the platform cannot make for it —
+   * whose rows a read returns, which fields a level may see.
+   *
+   * The platform still decides IF the request arrives: the gate has already allowed it, and an owner-only
+   * path declared in the manifest was refused before reaching here. These headers are for what the plugin
+   * does with a request that is legitimately its own.
+   */
+  permissionKey?: string;
 };
 
 /**
@@ -75,6 +86,7 @@ export function createSidecarProxy({
   onRegister,
   timeoutSeconds,
   bufferRequestBody,
+  permissionKey,
 }: SidecarProxyParams): SidecarProxy {
   let serverPort: number | null = null;
 
@@ -123,9 +135,31 @@ export function createSidecarProxy({
       const value = ctx.req.header(header);
       if (value) headers[header] = value;
     }
-    // The authenticated owner, so the sidecar can scope its data. The sidecar binds loopback only, so it
-    // trusts this header — which is exactly why nothing but this proxy may set it.
-    headers['X-Officer-User'] = String(ctx.get('user').id);
+    // ── Who is asking ──
+    //
+    // The sidecar binds loopback only and trusts these, which is exactly why nothing but this proxy may
+    // set them. Note the loop above: it copies a THREE-ITEM ALLOWLIST off the inbound request, so a
+    // client-supplied `X-Officer-Owner: 1` cannot reach a sidecar. If that is ever changed to a
+    // copy-everything-except, it becomes privilege escalation against every plugin at once.
+    //
+    // Facts, never the role name. A plugin branching on `Super Admin` would give every plugin repository
+    // an opinion about the platform's role vocabulary, and renaming a role would silently change
+    // authorization in code the platform does not own and cannot see. `isOwner` is user id 1, pinned by a
+    // CHECK constraint; it will mean the same thing in a year. A plugin wanting an "Admins too" tier
+    // declares a second permission and lets the owner grant it, which keeps that answer on the
+    // permissions page instead of compiled into an `if`.
+    const userId = ctx.get('user').id;
+    headers['X-Officer-User'] = String(userId);
+
+    if (permissionKey) {
+      // Cached by role in `authorize.ts`, and the gate has already computed this for the same request, so
+      // this is a map lookup rather than a query.
+      const { isOwner, grants } = await getEffectivePermissions(userId);
+      headers['X-Officer-Owner'] = isOwner ? '1' : '0';
+      // The owner holds every permission implicitly and appears in no grants map — reporting their level
+      // as the absent 'none' would invert the meaning for the one account that can do everything.
+      headers['X-Officer-Level'] = isOwner ? 'write' : (grants.get(permissionKey) ?? 'none');
+    }
 
     const hasBody = method !== 'GET' && method !== 'HEAD';