feat(KB-196): load extension providers for dashboard model selector

- Load pi extensions on dashboard startup to register custom model providers
- Include extension-provided models in the dashboard model selector
- Add comprehensive tests for extension model loading and error handling
- Create changeset for patch release fixing model selector extensions

packages/cli/src/commands/__tests__/dashboard.test.ts

@@ -101,13 +101,24 @@ vi.mock("@kb/engine", async (importOriginal) => {
 // ── Mock @mariozechner/pi-coding-agent ──────────────────────────────
 
 const mockAuthStorage = { getAuth: vi.fn(), setAuth: vi.fn() };
-const mockModelRegistry = { getModels: vi.fn().mockResolvedValue([]) };
+const mockModelRegistry = {
+  getModels: vi.fn().mockResolvedValue([]),
+  registerProvider: vi.fn(),
+  refresh: vi.fn(),
+};
+const mockDiscoverAndLoadExtensions = vi.fn().mockResolvedValue({
+  runtime: { pendingProviderRegistrations: [] },
+  errors: [],
+});
+const mockCreateExtensionRuntime = vi.fn();
 
 vi.mock("@mariozechner/pi-coding-agent", () => ({
   AuthStorage: {
     create: vi.fn(() => mockAuthStorage),
   },
   ModelRegistry: vi.fn().mockImplementation(() => mockModelRegistry),
+  discoverAndLoadExtensions: mockDiscoverAndLoadExtensions,
+  createExtensionRuntime: mockCreateExtensionRuntime,
 }));
 
 // ── Import module under test (after mocks) ──────────────────────────
@@ -119,6 +130,10 @@ const { runDashboard } = await import("../dashboard.js");
 describe("runDashboard — AuthStorage & ModelRegistry wiring", () => {
   beforeEach(async () => {
     vi.clearAllMocks();
+    mockDiscoverAndLoadExtensions.mockResolvedValue({
+      runtime: { pendingProviderRegistrations: [] },
+      errors: [],
+    });
     const { TaskStore } = await import("@kb/core");
     (TaskStore as ReturnType<typeof vi.fn>).mockImplementation(() => makeMockStore());
   });
@@ -150,4 +165,81 @@ describe("runDashboard — AuthStorage & ModelRegistry wiring", () => {
     expect(ModelRegistry).toHaveBeenCalledTimes(1);
     expect(ModelRegistry).toHaveBeenCalledWith(mockAuthStorage);
   });
+
+  it("discovers extensions and registers extension providers", async () => {
+    mockDiscoverAndLoadExtensions.mockResolvedValueOnce({
+      runtime: {
+        pendingProviderRegistrations: [
+          {
+            name: "custom-anthropic",
+            config: { models: [{ id: "claude-sonnet-4-5" }] },
+            extensionPath: "/extensions/custom-anthropic",
+          },
+        ],
+      },
+      errors: [],
+    });
+
+    await runDashboard(0, {});
+
+    expect(mockDiscoverAndLoadExtensions).toHaveBeenCalledWith([], expect.any(String), undefined);
+    expect(mockModelRegistry.registerProvider).toHaveBeenCalledWith(
+      "custom-anthropic",
+      expect.objectContaining({ models: [{ id: "claude-sonnet-4-5" }] }),
+    );
+    expect(mockModelRegistry.refresh).toHaveBeenCalled();
+  });
+
+  it("logs extension load errors without aborting startup", async () => {
+    const consoleSpy = vi.spyOn(console, "log").mockImplementation(() => {});
+    mockDiscoverAndLoadExtensions.mockResolvedValueOnce({
+      runtime: { pendingProviderRegistrations: [] },
+      errors: [{ path: "/extensions/bad", error: "Invalid manifest" }],
+    });
+
+    await runDashboard(0, {});
+
+    expect(consoleSpy).toHaveBeenCalledWith("[extensions] Failed to load /extensions/bad: Invalid manifest");
+    expect(consoleSpy).toHaveBeenCalledWith(expect.stringContaining("kb board"));
+    consoleSpy.mockRestore();
+  });
+
+  it("falls back gracefully when extension discovery throws", async () => {
+    const consoleSpy = vi.spyOn(console, "log").mockImplementation(() => {});
+    mockDiscoverAndLoadExtensions.mockRejectedValueOnce(new Error("boom"));
+
+    await runDashboard(0, {});
+
+    expect(mockCreateExtensionRuntime).toHaveBeenCalledTimes(1);
+    expect(mockModelRegistry.refresh).toHaveBeenCalled();
+    expect(consoleSpy).toHaveBeenCalledWith("[extensions] Failed to discover extensions: boom");
+    consoleSpy.mockRestore();
+  });
+
+  it("logs provider registration errors without aborting startup", async () => {
+    const consoleSpy = vi.spyOn(console, "log").mockImplementation(() => {});
+    mockDiscoverAndLoadExtensions.mockResolvedValueOnce({
+      runtime: {
+        pendingProviderRegistrations: [
+          {
+            name: "duplicate-provider",
+            config: { models: [{ id: "model-a" }] },
+            extensionPath: "/extensions/duplicate-provider",
+          },
+        ],
+      },
+      errors: [],
+    });
+    mockModelRegistry.registerProvider.mockImplementationOnce(() => {
+      throw new Error("duplicate provider");
+    });
+
+    await runDashboard(0, {});
+
+    expect(consoleSpy).toHaveBeenCalledWith(
+      "[extensions] Failed to register provider from /extensions/duplicate-provider: duplicate provider",
+    );
+    expect(mockModelRegistry.refresh).toHaveBeenCalled();
+    consoleSpy.mockRestore();
+  });
 });

packages/cli/src/commands/dashboard.test.ts

@@ -164,6 +164,28 @@ vi.mock("@kb/engine", async (importOriginal) => {
   };
 });
 
+// ── Mock @mariozechner/pi-coding-agent ──────────────────────────────
+
+const mockAuthStorage = { getAuth: vi.fn(), setAuth: vi.fn() };
+const mockModelRegistry = {
+  registerProvider: vi.fn(),
+  refresh: vi.fn(),
+};
+const mockDiscoverAndLoadExtensions = vi.fn().mockResolvedValue({
+  runtime: { pendingProviderRegistrations: [] },
+  errors: [],
+});
+const mockCreateExtensionRuntime = vi.fn();
+
+vi.mock("@mariozechner/pi-coding-agent", () => ({
+  AuthStorage: {
+    create: vi.fn(() => mockAuthStorage),
+  },
+  ModelRegistry: vi.fn().mockImplementation(() => mockModelRegistry),
+  discoverAndLoadExtensions: mockDiscoverAndLoadExtensions,
+  createExtensionRuntime: mockCreateExtensionRuntime,
+}));
+
 // ── Import module under test (after mocks) ──────────────────────────
 
 const { runDashboard, processPullRequestMergeTask, getMergeStrategy, getTaskBranchName } = await import("./dashboard.js");

packages/cli/src/commands/dashboard.ts

@@ -5,7 +5,7 @@ import { TaskStore, AutomationStore } from "@kb/core";
 import type { Settings, TaskDetail, PrInfo } from "@kb/core";
 import { createServer, GitHubClient } from "@kb/dashboard";
 import { TriageProcessor, TaskExecutor, Scheduler, AgentSemaphore, WorktreePool, aiMergeTask, UsageLimitPauser, PRIORITY_MERGE, scanIdleWorktrees, cleanupOrphanedWorktrees, NtfyNotifier, PrMonitor, PrCommentHandler, CronRunner, StuckTaskDetector } from "@kb/engine";
-import { AuthStorage, ModelRegistry } from "@mariozechner/pi-coding-agent";
+import { AuthStorage, ModelRegistry, discoverAndLoadExtensions, createExtensionRuntime } from "@mariozechner/pi-coding-agent";
 
 /**
  * Prompt the user for a port number interactively.
@@ -453,6 +453,31 @@ export async function runDashboard(port: number, opts: { paused?: boolean; dev?:
   const authStorage = AuthStorage.create();
   const modelRegistry = new ModelRegistry(authStorage);
 
+  try {
+    const extensionsResult = await discoverAndLoadExtensions([], cwd, undefined);
+
+    for (const { path, error } of extensionsResult.errors) {
+      console.log(`[extensions] Failed to load ${path}: ${error}`);
+    }
+
+    for (const { name, config, extensionPath } of extensionsResult.runtime.pendingProviderRegistrations) {
+      try {
+        modelRegistry.registerProvider(name, config);
+      } catch (error) {
+        const message = error instanceof Error ? error.message : String(error);
+        console.log(`[extensions] Failed to register provider from ${extensionPath}: ${message}`);
+      }
+    }
+
+    extensionsResult.runtime.pendingProviderRegistrations = [];
+    modelRegistry.refresh();
+  } catch (error) {
+    const message = error instanceof Error ? error.message : String(error);
+    console.log(`[extensions] Failed to discover extensions: ${message}`);
+    createExtensionRuntime();
+    modelRegistry.refresh();
+  }
+
   // Start the web server with AI merge, auth, and model registry wired in
   const app = createServer(store, { onMerge, authStorage, modelRegistry, automationStore });