refactor(host): expose getHostAPI(); host-bin drops duplicate adapter; storage-sqlite manifest honesty

host CR-1: createHost.getHostAPI() returns the canonical post-activation HostAPI
(registration closed) via a single builder — host-bin deletes its
buildPostActivationHostAPI duplicate and calls host.getHostAPI().
storage-sqlite CR-2: remove false contributes.services:["storage"] (backend is a
kernel bootstrap dep injected as HostDeps.storageFactory, not a bus service);
document the intentional no-op activate.

typecheck clean, 218 tests pass, biome clean; live boot + curl verified.

5 files changed, 96 insertions, 39 deletions

diff --git a/packages/host-bin/src/main.ts b/packages/host-bin/src/main.ts
index e26b8c6..0cb0d37 100644
--- a/packages/host-bin/src/main.ts
+++ b/packages/host-bin/src/main.ts
@@ -8,7 +8,6 @@ import {
 	createHost,
 	type EventsEmitter,
 	type Extension,
-	type HostAPI,
 	type HostDeps,
 	type Logger,
 	type PermissionGate,
@@ -54,41 +53,6 @@ function createNoopEvents(): EventsEmitter {
 	return { emit: () => {} };
 }
 
-function buildPostActivationHostAPI(
-	host: {
-		getProviders: () => ReadonlyMap<string, unknown>;
-		getTools: () => ReadonlyMap<string, unknown>;
-		getAuthProviders: () => ReadonlyMap<string, unknown>;
-		getAuthProvider: (id: string) => unknown;
-	},
-	deps: HostDeps,
-): HostAPI {
-	const notAvailable = () => {
-		throw new Error("Registration not available after activation");
-	};
-	return {
-		defineTool: notAvailable,
-		defineProvider: notAvailable,
-		defineAuth: notAvailable,
-		on: (hook, handler) => deps.bus.on(hook, handler),
-		addFilter: (hook, fn) => deps.bus.addFilter(hook, fn),
-		provideService: (handle, impl) => deps.bus.provideService(handle, impl),
-		getService: (handle) => deps.bus.getService(handle),
-		storage: (namespace: string) => deps.storageFactory(namespace),
-		config: deps.config,
-		secrets: deps.secrets,
-		permissions: deps.permissions,
-		events: deps.events,
-		logger: deps.logger,
-		getProviders: () => host.getProviders() as ReturnType<HostAPI["getProviders"]>,
-		getTools: () => host.getTools() as ReturnType<HostAPI["getTools"]>,
-		getAuthProviders: () => host.getAuthProviders() as ReturnType<HostAPI["getAuthProviders"]>,
-		getAuthProvider: (id: string) =>
-			host.getAuthProvider(id) as ReturnType<HostAPI["getAuthProvider"]>,
-		scheduler: { register: (job: ScheduledJob) => deps.scheduler.register(job) },
-	};
-}
-
 const CORE_EXTENSIONS: readonly Extension[] = [
 	storageSqliteExt,
 	conversationStoreExt,
@@ -131,7 +95,7 @@ async function boot(): Promise<void> {
 		}
 	}
 
-	const hostAPI = buildPostActivationHostAPI(host, deps);
+	const hostAPI = host.getHostAPI();
 	const app = createServer(hostAPI);
 
 	// Port precedence: BACKEND_PORT (the rewrite's assigned port) → PORT → default.
diff --git a/packages/kernel/src/host/host.test.ts b/packages/kernel/src/host/host.test.ts
index 82d5177..11c2356 100644
--- a/packages/kernel/src/host/host.test.ts
+++ b/packages/kernel/src/host/host.test.ts
@@ -687,4 +687,67 @@ describe("createHost", () => {
 			expect(host.getDisabled()).toHaveLength(0);
 		});
 	});
+
+	describe("getHostAPI", () => {
+		it("returns a HostAPI whose read-views reflect registrations from activation", async () => {
+			const tool = createFakeTool("read-file");
+			const provider = createFakeProvider("anthropic");
+			const auth = createFakeAuth("apikey");
+
+			const ext = createExtension("multi-ext", {
+				activate: (host) => {
+					host.defineTool(tool);
+					host.defineProvider(provider);
+					host.defineAuth(auth);
+				},
+			});
+
+			const host = createHost([ext], deps);
+			await host.activate();
+
+			const api = host.getHostAPI();
+
+			expect(api.getTools().size).toBe(1);
+			expect(api.getTools().get("read-file")).toBe(tool);
+
+			expect(api.getProviders().size).toBe(1);
+			expect(api.getProviders().get("anthropic")).toBe(provider);
+
+			expect(api.getAuthProviders().size).toBe(1);
+			expect(api.getAuthProvider("apikey")).toBe(auth);
+		});
+
+		it("throws on defineTool after activation", async () => {
+			const ext = createExtension("ext", { activate: () => {} });
+			const host = createHost([ext], deps);
+			await host.activate();
+
+			const api = host.getHostAPI();
+			expect(() => api.defineTool(createFakeTool("late"))).toThrow(
+				"Registration not available after activation",
+			);
+		});
+
+		it("throws on defineProvider after activation", async () => {
+			const ext = createExtension("ext", { activate: () => {} });
+			const host = createHost([ext], deps);
+			await host.activate();
+
+			const api = host.getHostAPI();
+			expect(() => api.defineProvider(createFakeProvider("late"))).toThrow(
+				"Registration not available after activation",
+			);
+		});
+
+		it("throws on defineAuth after activation", async () => {
+			const ext = createExtension("ext", { activate: () => {} });
+			const host = createHost([ext], deps);
+			await host.activate();
+
+			const api = host.getHostAPI();
+			expect(() => api.defineAuth(createFakeAuth("late"))).toThrow(
+				"Registration not available after activation",
+			);
+		});
+	});
 });
diff --git a/packages/kernel/src/host/host.ts b/packages/kernel/src/host/host.ts
index 8592a16..dd61f9f 100644
--- a/packages/kernel/src/host/host.ts
+++ b/packages/kernel/src/host/host.ts
@@ -54,6 +54,7 @@ export interface Host {
 	readonly getScheduledJobs: () => readonly ScheduledJob[];
 	readonly getMigrations: () => readonly string[];
 	readonly getDisabled: () => readonly DisabledExtension[];
+	readonly getHostAPI: () => HostAPI;
 }
 
 export function createHost(extensions: readonly Extension[], deps: HostDeps): Host {
@@ -95,15 +96,19 @@ export function createHost(extensions: readonly Extension[], deps: HostDeps): Ho
 		}
 	}
 
-	function buildHostAPI(): HostAPI {
+	function buildHostAPI(opts?: { readonly registrationClosed?: boolean }): HostAPI {
+		const closed = opts?.registrationClosed ?? false;
 		return {
 			defineTool(tool: ToolContract) {
+				if (closed) throw new Error("Registration not available after activation");
 				tools.set(tool.name, tool);
 			},
 			defineProvider(provider: ProviderContract) {
+				if (closed) throw new Error("Registration not available after activation");
 				providers.set(provider.id, provider);
 			},
 			defineAuth(auth: AuthContract) {
+				if (closed) throw new Error("Registration not available after activation");
 				authProviders.set(auth.id, auth);
 			},
 			on<TPayload>(hook: EventHookDescriptor<TPayload>, handler: EventHandler<TPayload>) {
@@ -201,5 +206,8 @@ export function createHost(extensions: readonly Extension[], deps: HostDeps): Ho
 		getDisabled() {
 			return disabled;
 		},
+		getHostAPI() {
+			return buildHostAPI({ registrationClosed: true });
+		},
 	};
 }
diff --git a/packages/storage-sqlite/src/extension.ts b/packages/storage-sqlite/src/extension.ts
index 63a71af..32297e5 100644
--- a/packages/storage-sqlite/src/extension.ts
+++ b/packages/storage-sqlite/src/extension.ts
@@ -7,11 +7,11 @@ export const manifest: Manifest = {
 	apiVersion: "^0.1.0",
 	trust: "bundled",
 	capabilities: { db: true },
-	contributes: { services: ["storage"] },
 	activation: "eager",
 };
 
 export const extension: Extension = {
 	manifest,
+	// No-op: the SQLite backend is a kernel bootstrap dep injected via HostDeps.storageFactory, not a bus service.
 	activate: async (_host: HostAPI) => {},
 };
diff --git a/tasks.md b/tasks.md
index 83e9bf7..3777b23 100644
--- a/tasks.md
+++ b/tasks.md
@@ -100,3 +100,25 @@ contained a real **`tool-call` + `tool-result`** round-trip and the final answer
 quoted the file's secret passphrase (MAGENTA-OTTER-42) correctly. The kernel
 tool-dispatch loop is now proven end-to-end against a live model (§3.3). Summon:
 prompts/step2-tool-read-file.md, report: reports/step2-tool-read-file.md.
+
+### Step 3 — Small CRs / hygiene  [x] DONE (verified live)
+Parallel summons (disjoint file sets, mimo-v2.5-pro; output→reports/*.run.log):
+- **host CR-1** (kernel-host owner): `createHost` exposes `getHostAPI()` (registration
+  closed post-activation) so host-bin drops its `buildPostActivationHostAPI` duplicate.
+  prompts/step3-kernel-host.md. Files: packages/kernel/src/host/{host.ts,host.test.ts}.
+- **storage-sqlite CR-2** (owner): remove false `contributes.services:["storage"]`
+  from manifest (backend is a kernel bootstrap dep via HostDeps.storageFactory, not a
+  bus service); document the intentional no-op activate. prompts/step3-storage-sqlite.md.
+  Files: packages/storage-sqlite/src/extension.ts.
+After both land: orchestrator wires host-bin to use `host.getHostAPI()` (deletes adapter).
+
+**Step 3 RESULT:** done + verified. (1) kernel-host: `createHost` now exposes
+`getHostAPI()` returning the canonical post-activation HostAPI with registration
+methods closed (single builder w/ `registrationClosed` flag — zero duplication);
++4 host tests. (2) storage-sqlite: removed false `contributes.services:["storage"]`;
+documented the intentional no-op activate (backend is a kernel bootstrap dep via
+HostDeps.storageFactory). (3) host-bin wiring (orchestrator): deleted the
+`buildPostActivationHostAPI` adapter, now calls `host.getHostAPI()`; dropped the
+now-unused `HostAPI` import. typecheck clean, **218 tests pass**, biome clean.
+Live boot: all 7 extensions activate, curl returns real responses. Summons:
+prompts/step3-{kernel-host,storage-sqlite}.md (mimo-v2.5-pro, parallel, disjoint).