diff --git a/CHANGELOG.md b/CHANGELOG.md
index ed70b83..be318e0 100644
--- a/CHANGELOG.md
+++ b/CHANGELOG.md
@@ -17,6 +17,15 @@ follows [Semantic Versioning](https://semver.org).
   `onPageMove` is also a valid webhook event. Needs `@dune/core` with `onPageMove` (0.36).
   `tests/admin/page_events_test.ts` drives create, update, reorder, delete and restore through the real routes.
 
+### Changed — BREAKING (the admin declares its own extension points, #127)
+
+- **`AdminPageRegistration`, `AdminRouteRegistration` and `ContentEditorPlugin` live here now**, exported
+  from `@dune/plugin-admin` (and `@dune/plugin-admin/contributions`). Core's contract never read them. The
+  keys `admin.pages` and `admin.routes` are declared by this package by declaration merging, so importing
+  the types is what makes a plugin's `contribute("admin.pages", ...)` type-check. The `editor.content`
+  slot is renamed **`admin.editor`**: a key carries the name of the plugin that reads it. A plugin that
+  provides a replacement page editor changes the key and imports `ContentEditorPlugin` from here.
+
 ### Changed — BREAKING (the admin is called `admin`, and its settings are its plugin config)
 
 - **The plugin is named `admin`** (it was `dune-admin`), so its settings are `config.plugins.admin`, and
diff --git a/deno.json b/deno.json
index d6274b4..1b48fe1 100644
--- a/deno.json
+++ b/deno.json
@@ -13,6 +13,7 @@
     "./admin/mount": "./src/admin/mount.ts",
     "./admin/context": "./src/admin/context.ts",
     "./admin/types": "./src/admin/types.ts",
+    "./contributions": "./src/admin/contributions.ts",
     "./admin/guards": "./src/admin/guards.ts",
     "./admin/auth/middleware": "./src/admin/auth/middleware.ts",
     "./admin/auth/provider": "./src/admin/auth/provider.ts",
diff --git a/mod.ts b/mod.ts
index 602d373..dc7e8f6 100644
--- a/mod.ts
+++ b/mod.ts
@@ -52,6 +52,17 @@ const _core = corePlugins as unknown as {
 
 /** The `@dune/core` instance sentinel this package resolved. See core's `plugins/mod.ts`. */
 export const resolvedCoreSentinel: unknown = _core.CORE_INSTANCE;
+/**
+ * The admin's extension points. Importing them also teaches TypeScript the keys
+ * (`admin.pages`, `admin.routes`, `admin.editor`) this plugin declares on the
+ * capability registry.
+ */
+export type {
+  AdminPageRegistration,
+  AdminRouteRegistration,
+  ContentEditorPlugin,
+} from "./src/admin/contributions.ts";
+
 /** The `@dune/core` version this package resolved. Undefined on cores ≤0.30. */
 export const resolvedCoreVersion: string | undefined = _core.CORE_VERSION;
 
@@ -273,7 +284,7 @@ export function createAdminPlugin(opts: AdminPluginOptions): DunePlugin {
 
       // ── Default content editor ────────────────────────────────────────────────
       const inlineEdit = capabilities.get("editor.inline");
-      const contentEditor = capabilities.get("editor.content") ?? createBlockEditorPlugin();
+      const contentEditor = capabilities.get("admin.editor") ?? createBlockEditorPlugin();
 
       // ── Build AdminContext ────────────────────────────────────────────────────
       const metricsEnabled = config.system.metrics?.enabled !== false;
diff --git a/src/admin/block-editor-plugin.tsx b/src/admin/block-editor-plugin.tsx
index a166a4b..62b959d 100644
--- a/src/admin/block-editor-plugin.tsx
+++ b/src/admin/block-editor-plugin.tsx
@@ -1,14 +1,14 @@
 /** @jsxImportSource preact */
 /**
  * Built-in block editor — the default ContentEditorPlugin loaded by bootstrap
- * when no plugin provides the `editor.content` capability.
+ * when no plugin provides the `admin.editor` capability.
  *
  * Wraps the PageEditor island in the same way the old hardwired route did, but
  * now as a proper ContentEditorPlugin so it participates in the same slot that
  * third-party editors use.
  */
 
-import type { ContentEditorPlugin } from "@dune/core/hooks";
+import type { ContentEditorPlugin } from "./contributions.ts";
 import type { FreshContext } from "fresh";
 import PageEditor from "./islands/PageEditor.tsx";
 
diff --git a/src/admin/context.ts b/src/admin/context.ts
index e90e973..90c2178 100644
--- a/src/admin/context.ts
+++ b/src/admin/context.ts
@@ -17,8 +17,8 @@ import type { Scheduler, ScheduledAction } from "@dune/core/workflow";
 import type { HistoryEngine } from "@dune/core/history";
 import type { SubmissionManager } from "./submissions.ts";
 import type { FlexEngine } from "@dune/core/flex";
-import type { HookRegistry, AdminPageRegistration, AdminRouteRegistration } from "@dune/core/hooks";
-import type { ContentEditorPlugin } from "@dune/core/hooks";
+import type { HookRegistry } from "@dune/core/hooks";
+import type { AdminPageRegistration, AdminRouteRegistration, ContentEditorPlugin } from "./contributions.ts";
 import type { StagingEngine } from "@dune/core/staging";
 import type { CommentManager } from "./comments.ts";
 import type { CollabManager } from "../collab/mod.ts";
@@ -68,7 +68,7 @@ export interface AdminContext {
   collab?: CollabManager;
   /** Inline editing manager, provided by a plugin as the `editor.inline` capability. */
   inlineEdit?: InlineEditManager;
-  /** Custom page editor, provided by a plugin as the `editor.content` capability. Replaces the built-in block editor. */
+  /** Custom page editor, provided by a plugin as the `admin.editor` capability. Replaces the built-in block editor. */
   contentEditor?: ContentEditorPlugin;
   auditLogger?: AuditLogger;
   metrics?: MetricsCollector;
diff --git a/src/admin/contributions.ts b/src/admin/contributions.ts
new file mode 100644
index 0000000..e60720f
--- /dev/null
+++ b/src/admin/contributions.ts
@@ -0,0 +1,141 @@
+/**
+ * The admin's own extension points.
+ *
+ * Core's contract names none of these: it never reads them. The admin is their
+ * only consumer, so it declares them here, by declaration merging into the
+ * capability registry, under its own `admin.` prefix. A plugin that contributes
+ * an admin page, an admin route or a replacement page editor imports the types
+ * from `@dune/plugin-admin`; importing them is also what makes the keys known to
+ * TypeScript:
+ *
+ * ```ts
+ * import type { AdminPageRegistration } from "@dune/plugin-admin";
+ * api.capabilities.contribute("admin.pages", { path: "/billing", label: "Billing", permission: "billing.manage", handler });
+ * ```
+ *
+ * @module
+ */
+
+import type { PluginRouteContext } from "@dune/core/plugin-api";
+
+/**
+ * A custom admin page contributed by a plugin.
+ *
+ * Plugins contribute these to the `admin.pages` point:
+ * `api.capabilities.contribute("admin.pages", { path, label, permission, handler })`.
+ * Unlike `publicRoutes`, this is **not** wired by `@dune/core`: the admin reads the list
+ * (`capabilities.list("admin.pages")`) and mounts each page as a programmatic route,
+ * enforcing its declared `permission`. A site without the admin gets no admin pages.
+ *
+ * @since 4.0.0
+ */
+// deno-lint-ignore no-explicit-any
+export interface AdminPageRegistration<S = any> {
+  /**
+   * URL path relative to the admin prefix (must start with `/`).
+   * Example: `/my-plugin` registers at `/admin/my-plugin`.
+   */
+  path: string;
+  /** Human-readable nav label shown in the admin sidebar */
+  label: string;
+  /** Optional icon — emoji or inline SVG */
+  icon?: string;
+  /**
+   * Admin permission required to view this page. Required, like
+   * {@link AdminRouteRegistration.permission}: every admin contribution says
+   * who may use it, so a page cannot be exposed to every authenticated admin
+   * by leaving a field out.
+   */
+  permission: string;
+  /** GET handler for the page (a method, so a full Fresh context is accepted: see {@link PluginRouteContext}). */
+  handler(ctx: PluginRouteContext<S>): Promise<Response> | Response;
+}
+
+/**
+ * A guarded admin route contributed by a plugin: the way to add a `POST`, `PUT`,
+ * `PATCH` or `DELETE` endpoint (or a `GET` API route that is not a sidebar page)
+ * under the admin prefix.
+ *
+ * Plugins contribute these to the `admin.routes` point:
+ * `api.capabilities.contribute("admin.routes", { method, path, permission, handler })`.
+ * The admin reads the list
+ * (`capabilities.list("admin.routes")`) and mounts each route behind its own
+ * authentication, with the CSRF check applied to every non-safe method and the
+ * declared `permission` enforced, so the handler only runs for a request that
+ * passed all three. A site without the admin mounts nothing.
+ *
+ * A route registered directly in a plugin's `mount()` is *not* behind the
+ * admin's middleware (mount order is registration order, and the admin mounts
+ * last), so it cannot use the admin's guards: contribute it here instead.
+ *
+ * @since 4.0.0
+ */
+// deno-lint-ignore no-explicit-any
+export interface AdminRouteRegistration<S = any> {
+  /** HTTP method. Anything other than `GET` is subject to the CSRF check. */
+  method: "GET" | "POST" | "PUT" | "PATCH" | "DELETE";
+  /**
+   * URL path relative to the admin prefix (must start with `/`).
+   * Example: `/my-plugin/save` registers at `/admin/my-plugin/save`.
+   */
+  path: string;
+  /**
+   * Admin permission required (including ones the plugin declares through
+   * `authzActions`). Required, not optional: a mutation endpoint must say who
+   * may call it, so it cannot be mounted open to every authenticated admin by
+   * leaving a field out.
+   */
+  permission: string;
+  /** Handler; runs only after authentication, CSRF and permission checks pass (a method, so a full Fresh context is accepted). */
+  handler(ctx: PluginRouteContext<S>): Promise<Response> | Response;
+}
+
+/**
+ * Plugin-provided replacement for the built-in block editor.
+ *
+ * Provide it as the `admin.editor` capability: `api.capabilities.provide("admin.editor", () => impl)`.
+ * The edit route delegates to `pageEditorHandler` instead of the default block editor.
+ *
+ * Declared by the admin plugin, which is the only reader of the `admin.editor` slot; a plugin
+ * that provides one imports this type from `@dune/plugin-admin`.
+ *
+ * @since 4.0.0
+ */
+export interface ContentEditorPlugin {
+  /**
+   * Handle `GET /admin/pages/edit?path=...`.
+   *
+   * Core passes the full Fresh context: annotate `ctx` as `FreshContext` and call
+   * `ctx.render(component)` to render within the admin layout, or return any
+   * `Response` directly. An unannotated `ctx` is a {@link PluginRouteContext}.
+   * Access `ctx.state.adminContext` for engine, config, and other admin services.
+   * The context state type is `AdminState` from `@dune/plugin-admin`; typed as
+   * `any` here so core does not depend on admin-internal types.
+   */
+  pageEditorHandler(ctx: PluginRouteContext): Response | Promise<Response>;
+
+  /**
+   * Optional WebSocket upgrade handler for real-time collaboration.
+   *
+   * When present, `GET /admin/api/content-editor/ws?path=...` delegates here
+   * after auth and path validation. Return a `101 Switching Protocols` response
+   * via `Deno.upgradeWebSocket`. When absent the WS endpoint responds 501.
+   */
+  wsHandler?: (
+    req: Request,
+    user: { id: string; name: string },
+  ) => Response;
+}
+
+declare module "@dune/core/plugin-api" {
+  interface Capabilities {
+    /** A replacement page editor. Consumer: the admin. */
+    "admin.editor": ContentEditorPlugin;
+  }
+  interface Contributions {
+    /** An extra admin page. Consumer: the admin. */
+    "admin.pages": AdminPageRegistration;
+    /** A guarded admin route (any method) under the admin prefix. Consumer: the admin, which applies authentication, CSRF and permission checks. */
+    "admin.routes": AdminRouteRegistration;
+  }
+}
diff --git a/src/admin/types.ts b/src/admin/types.ts
index 1cdb749..6890004 100644
--- a/src/admin/types.ts
+++ b/src/admin/types.ts
@@ -4,7 +4,7 @@
  * @module
  */
 
-export type { ContentEditorPlugin } from "@dune/core/hooks";
+export type { AdminPageRegistration, AdminRouteRegistration, ContentEditorPlugin } from "./contributions.ts";
 // Session and Role live in core to break circular deps; import for
 // local use AND re-export so callers importing from admin/types get them.
 // Session was formerly AdminSession — renamed in
diff --git a/tests/admin/capabilities_e2e_test.ts b/tests/admin/capabilities_e2e_test.ts
index 4c22822..d75a4f0 100644
--- a/tests/admin/capabilities_e2e_test.ts
+++ b/tests/admin/capabilities_e2e_test.ts
@@ -104,7 +104,7 @@ Deno.test(
 );
 
 Deno.test(
-  "admin uses the editor.content slot another plugin provides",
+  "admin uses the admin.editor slot another plugin provides",
   { sanitizeOps: false, sanitizeResources: false },
   async () => {
     const editor: DunePlugin = {
@@ -112,15 +112,15 @@ Deno.test(
       version: "1.0.0",
       hooks: {},
       setup(api) {
-        api.capabilities.provide("editor.content", () => ({
+        api.capabilities.provide("admin.editor", () => ({
           pageEditorHandler: () => new Response("custom editor"),
         }));
       },
     };
     await withSite([editor], async (ctx) => {
-      assertExists(ctx.capabilities.get("editor.content"));
+      assertExists(ctx.capabilities.get("admin.editor"));
       assertEquals(
-        ctx.capabilities.providers().find((p) => p.name === "editor.content")?.provider,
+        ctx.capabilities.providers().find((p) => p.name === "admin.editor")?.provider,
         "test-editor",
       );
     });
diff --git a/tests/admin/contributions_types_test.ts b/tests/admin/contributions_types_test.ts
new file mode 100644
index 0000000..cb6cfdc
--- /dev/null
+++ b/tests/admin/contributions_types_test.ts
@@ -0,0 +1,46 @@
+/**
+ * The admin declares its own extension points. These checks fail to compile if
+ * the declaration merging, the required `permission`, or the handler typing
+ * regresses; the runtime assertions only keep the tests honest.
+ */
+
+import { assertEquals } from "@std/assert";
+import type { FreshContext } from "fresh";
+import { createCapabilityRegistry } from "@dune/core/plugin-api";
+import type { AdminPageRegistration, AdminRouteRegistration, ContentEditorPlugin } from "../../mod.ts";
+
+Deno.test("importing the admin's types teaches TypeScript its keys", () => {
+  const reg = createCapabilityRegistry();
+  const page: AdminPageRegistration = { path: "/p", label: "P", permission: "pages.read", handler: () => new Response("") };
+  reg.registrar("x").contribute("admin.pages", page);
+  assertEquals(reg.reader.list("admin.pages").map((p) => p.path), ["/p"]);
+});
+
+Deno.test("an admin.pages contribution must name a permission (compile-time)", () => {
+  const reg = createCapabilityRegistry();
+  // @ts-expect-error `permission` is required on admin.pages
+  reg.registrar("a").contribute("admin.pages", { path: "/x", label: "X", handler: () => new Response("") });
+  assertEquals(reg.reader.list("admin.pages").length, 1);
+});
+
+Deno.test("an admin.routes contribution must name a permission (compile-time)", () => {
+  const reg = createCapabilityRegistry();
+  // @ts-expect-error `permission` is required on admin.routes
+  reg.registrar("a").contribute("admin.routes", { method: "POST", path: "/x", handler: () => new Response("") });
+  assertEquals(reg.reader.list("admin.routes").length, 1);
+});
+
+Deno.test("contribution handlers may be written against a full Fresh context", () => {
+  // `handler` is declared as a method, so the parameter is checked bivariantly.
+  const full = (ctx: FreshContext<{ n: number }>) => new Response(String(ctx.state.n));
+  const page: AdminPageRegistration<{ n: number }> = { path: "/p", label: "P", permission: "pages.read", handler: full };
+  const route: AdminRouteRegistration<{ n: number }> = { method: "POST", path: "/r", permission: "pages.update", handler: full };
+  assertEquals([page.path, route.path], ["/p", "/r"]);
+});
+
+Deno.test("admin.editor takes a ContentEditorPlugin", () => {
+  const reg = createCapabilityRegistry();
+  const editor: ContentEditorPlugin = { pageEditorHandler: () => new Response("") };
+  reg.registrar("alt-editor").provide("admin.editor", () => editor);
+  assertEquals(reg.reader.providers()[0].name, "admin.editor");
+});