diff --git a/cli/src/__tests__/validate-implementation-branches.test.ts b/cli/src/__tests__/validate-implementation-branches.test.ts
new file mode 100644
index 00000000..4c1a776f
--- /dev/null
+++ b/cli/src/__tests__/validate-implementation-branches.test.ts
@@ -0,0 +1,699 @@
+import { describe, it, expect, beforeEach, afterEach, mock, spyOn } from "bun:test";
+import { createMockManifest, createConsoleMocks, restoreMocks } from "./test-helpers";
+import { loadManifest } from "../manifest";
+
+/**
+ * Tests for validateImplementation branching in commands.ts (lines 233-256).
+ *
+ * When a user requests an unimplemented agent+cloud combination, validateImplementation
+ * shows different messages depending on how many other clouds ARE available:
+ *
+ * 1. availableClouds.length > 0 && <= 3: show all available clouds as examples
+ * 2. availableClouds.length > 3: show first 3, then "Run spawn X to see all N options"
+ * 3. availableClouds.length === 0: show "no implemented cloud providers yet" + suggest "spawn list"
+ *
+ * Existing tests (commands-error-paths.test.ts) only cover case 1 with exactly 1 cloud.
+ * This file tests the untested cases 2 and 3, plus edge cases.
+ *
+ * Agent: test-engineer
+ */
+
+// ── Test manifests ────────────────────────────────────────────────────────────
+
+// Manifest with 5 clouds implemented for "claude" but "broken" cloud is NOT implemented
+// This tests the >3 branch: "Run spawn claude to see all 5 options"
+const manyCloudManifest = {
+  agents: {
+    claude: {
+      name: "Claude Code",
+      description: "AI coding assistant",
+      url: "https://claude.ai",
+      install: "npm install -g claude",
+      launch: "claude",
+      env: { ANTHROPIC_API_KEY: "test" },
+    },
+    aider: {
+      name: "Aider",
+      description: "AI pair programmer",
+      url: "https://aider.chat",
+      install: "pip install aider-chat",
+      launch: "aider",
+      env: { OPENAI_API_KEY: "test" },
+    },
+  },
+  clouds: {
+    sprite: {
+      name: "Sprite",
+      description: "Lightweight VMs",
+      url: "https://sprite.sh",
+      type: "vm",
+      auth: "token",
+      provision_method: "api",
+      exec_method: "ssh",
+      interactive_method: "ssh",
+    },
+    hetzner: {
+      name: "Hetzner Cloud",
+      description: "European cloud provider",
+      url: "https://hetzner.com",
+      type: "cloud",
+      auth: "HCLOUD_TOKEN",
+      provision_method: "api",
+      exec_method: "ssh",
+      interactive_method: "ssh",
+    },
+    vultr: {
+      name: "Vultr",
+      description: "Cloud compute",
+      url: "https://vultr.com",
+      type: "cloud",
+      auth: "VULTR_API_KEY",
+      provision_method: "api",
+      exec_method: "ssh",
+      interactive_method: "ssh",
+    },
+    linode: {
+      name: "Linode",
+      description: "Cloud hosting",
+      url: "https://linode.com",
+      type: "cloud",
+      auth: "LINODE_TOKEN",
+      provision_method: "api",
+      exec_method: "ssh",
+      interactive_method: "ssh",
+    },
+    digitalocean: {
+      name: "DigitalOcean",
+      description: "Cloud infrastructure",
+      url: "https://digitalocean.com",
+      type: "cloud",
+      auth: "DO_API_TOKEN",
+      provision_method: "api",
+      exec_method: "ssh",
+      interactive_method: "ssh",
+    },
+    broken: {
+      name: "Broken Cloud",
+      description: "Broken provider",
+      url: "https://broken.dev",
+      type: "cloud",
+      auth: "BROKEN_TOKEN",
+      provision_method: "api",
+      exec_method: "ssh",
+      interactive_method: "ssh",
+    },
+  },
+  matrix: {
+    "sprite/claude": "implemented",
+    "hetzner/claude": "implemented",
+    "vultr/claude": "implemented",
+    "linode/claude": "implemented",
+    "digitalocean/claude": "implemented",
+    "broken/claude": "missing",
+    "sprite/aider": "missing",
+    "hetzner/aider": "missing",
+    "vultr/aider": "missing",
+    "linode/aider": "missing",
+    "digitalocean/aider": "missing",
+    "broken/aider": "missing",
+  },
+};
+
+// Manifest where aider has exactly 3 implemented clouds (boundary case)
+const threeCloudManifest = {
+  agents: {
+    aider: {
+      name: "Aider",
+      description: "AI pair programmer",
+      url: "https://aider.chat",
+      install: "pip install aider-chat",
+      launch: "aider",
+      env: { OPENAI_API_KEY: "test" },
+    },
+  },
+  clouds: {
+    sprite: {
+      name: "Sprite",
+      description: "Lightweight VMs",
+      url: "https://sprite.sh",
+      type: "vm",
+      auth: "token",
+      provision_method: "api",
+      exec_method: "ssh",
+      interactive_method: "ssh",
+    },
+    hetzner: {
+      name: "Hetzner Cloud",
+      description: "European cloud provider",
+      url: "https://hetzner.com",
+      type: "cloud",
+      auth: "HCLOUD_TOKEN",
+      provision_method: "api",
+      exec_method: "ssh",
+      interactive_method: "ssh",
+    },
+    vultr: {
+      name: "Vultr",
+      description: "Cloud compute",
+      url: "https://vultr.com",
+      type: "cloud",
+      auth: "VULTR_API_KEY",
+      provision_method: "api",
+      exec_method: "ssh",
+      interactive_method: "ssh",
+    },
+    broken: {
+      name: "Broken Cloud",
+      description: "Broken provider",
+      url: "https://broken.dev",
+      type: "cloud",
+      auth: "BROKEN_TOKEN",
+      provision_method: "api",
+      exec_method: "ssh",
+      interactive_method: "ssh",
+    },
+  },
+  matrix: {
+    "sprite/aider": "implemented",
+    "hetzner/aider": "implemented",
+    "vultr/aider": "implemented",
+    "broken/aider": "missing",
+  },
+};
+
+// Manifest where aider has exactly 4 clouds (first case >3)
+const fourCloudManifest = {
+  agents: {
+    aider: {
+      name: "Aider",
+      description: "AI pair programmer",
+      url: "https://aider.chat",
+      install: "pip install aider-chat",
+      launch: "aider",
+      env: { OPENAI_API_KEY: "test" },
+    },
+  },
+  clouds: {
+    sprite: {
+      name: "Sprite",
+      description: "Lightweight VMs",
+      url: "https://sprite.sh",
+      type: "vm",
+      auth: "token",
+      provision_method: "api",
+      exec_method: "ssh",
+      interactive_method: "ssh",
+    },
+    hetzner: {
+      name: "Hetzner Cloud",
+      description: "European cloud provider",
+      url: "https://hetzner.com",
+      type: "cloud",
+      auth: "HCLOUD_TOKEN",
+      provision_method: "api",
+      exec_method: "ssh",
+      interactive_method: "ssh",
+    },
+    vultr: {
+      name: "Vultr",
+      description: "Cloud compute",
+      url: "https://vultr.com",
+      type: "cloud",
+      auth: "VULTR_API_KEY",
+      provision_method: "api",
+      exec_method: "ssh",
+      interactive_method: "ssh",
+    },
+    linode: {
+      name: "Linode",
+      description: "Cloud hosting",
+      url: "https://linode.com",
+      type: "cloud",
+      auth: "LINODE_TOKEN",
+      provision_method: "api",
+      exec_method: "ssh",
+      interactive_method: "ssh",
+    },
+    broken: {
+      name: "Broken Cloud",
+      description: "Broken provider",
+      url: "https://broken.dev",
+      type: "cloud",
+      auth: "BROKEN_TOKEN",
+      provision_method: "api",
+      exec_method: "ssh",
+      interactive_method: "ssh",
+    },
+  },
+  matrix: {
+    "sprite/aider": "implemented",
+    "hetzner/aider": "implemented",
+    "vultr/aider": "implemented",
+    "linode/aider": "implemented",
+    "broken/aider": "missing",
+  },
+};
+
+// Manifest where aider has 0 clouds implemented
+const noCloudManifest = {
+  agents: {
+    aider: {
+      name: "Aider",
+      description: "AI pair programmer",
+      url: "https://aider.chat",
+      install: "pip install aider-chat",
+      launch: "aider",
+      env: { OPENAI_API_KEY: "test" },
+    },
+  },
+  clouds: {
+    sprite: {
+      name: "Sprite",
+      description: "Lightweight VMs",
+      url: "https://sprite.sh",
+      type: "vm",
+      auth: "token",
+      provision_method: "api",
+      exec_method: "ssh",
+      interactive_method: "ssh",
+    },
+    hetzner: {
+      name: "Hetzner Cloud",
+      description: "European cloud provider",
+      url: "https://hetzner.com",
+      type: "cloud",
+      auth: "HCLOUD_TOKEN",
+      provision_method: "api",
+      exec_method: "ssh",
+      interactive_method: "ssh",
+    },
+  },
+  matrix: {
+    "sprite/aider": "missing",
+    "hetzner/aider": "missing",
+  },
+};
+
+// Manifest where aider has exactly 2 clouds (existing tested case, included for completeness)
+const twoCloudManifest = {
+  agents: {
+    aider: {
+      name: "Aider",
+      description: "AI pair programmer",
+      url: "https://aider.chat",
+      install: "pip install aider-chat",
+      launch: "aider",
+      env: { OPENAI_API_KEY: "test" },
+    },
+  },
+  clouds: {
+    sprite: {
+      name: "Sprite",
+      description: "Lightweight VMs",
+      url: "https://sprite.sh",
+      type: "vm",
+      auth: "token",
+      provision_method: "api",
+      exec_method: "ssh",
+      interactive_method: "ssh",
+    },
+    hetzner: {
+      name: "Hetzner Cloud",
+      description: "European cloud provider",
+      url: "https://hetzner.com",
+      type: "cloud",
+      auth: "HCLOUD_TOKEN",
+      provision_method: "api",
+      exec_method: "ssh",
+      interactive_method: "ssh",
+    },
+    broken: {
+      name: "Broken Cloud",
+      description: "Broken provider",
+      url: "https://broken.dev",
+      type: "cloud",
+      auth: "BROKEN_TOKEN",
+      provision_method: "api",
+      exec_method: "ssh",
+      interactive_method: "ssh",
+    },
+  },
+  matrix: {
+    "sprite/aider": "implemented",
+    "hetzner/aider": "implemented",
+    "broken/aider": "missing",
+  },
+};
+
+// ── Mock @clack/prompts ───────────────────────────────────────────────────────
+
+const mockLogError = mock(() => {});
+const mockLogInfo = mock(() => {});
+const mockLogStep = mock(() => {});
+const mockLogWarn = mock(() => {});
+const mockSpinnerStart = mock(() => {});
+const mockSpinnerStop = mock(() => {});
+
+mock.module("@clack/prompts", () => ({
+  spinner: () => ({
+    start: mockSpinnerStart,
+    stop: mockSpinnerStop,
+    message: mock(() => {}),
+  }),
+  log: {
+    step: mockLogStep,
+    info: mockLogInfo,
+    error: mockLogError,
+    warn: mockLogWarn,
+    success: mock(() => {}),
+  },
+  intro: mock(() => {}),
+  outro: mock(() => {}),
+  cancel: mock(() => {}),
+  select: mock(() => {}),
+  isCancel: () => false,
+}));
+
+// Import commands after mock setup
+const { cmdRun } = await import("../commands.js");
+
+describe("validateImplementation branching", () => {
+  let consoleMocks: ReturnType<typeof createConsoleMocks>;
+  let originalFetch: typeof global.fetch;
+  let processExitSpy: ReturnType<typeof spyOn>;
+
+  function setManifest(manifest: any) {
+    global.fetch = mock(async () => ({
+      ok: true,
+      json: async () => manifest,
+      text: async () => JSON.stringify(manifest),
+    })) as any;
+    return loadManifest(true);
+  }
+
+  function getInfoMessages(): string[] {
+    return mockLogInfo.mock.calls.map((c: any[]) => c.join(" "));
+  }
+
+  function getErrorMessages(): string[] {
+    return mockLogError.mock.calls.map((c: any[]) => c.join(" "));
+  }
+
+  beforeEach(async () => {
+    consoleMocks = createConsoleMocks();
+    mockLogError.mockClear();
+    mockLogInfo.mockClear();
+    mockLogStep.mockClear();
+    mockLogWarn.mockClear();
+    mockSpinnerStart.mockClear();
+    mockSpinnerStop.mockClear();
+
+    processExitSpy = spyOn(process, "exit").mockImplementation((() => {
+      throw new Error("process.exit");
+    }) as any);
+
+    originalFetch = global.fetch;
+  });
+
+  afterEach(() => {
+    global.fetch = originalFetch;
+    processExitSpy.mockRestore();
+    restoreMocks(consoleMocks.log, consoleMocks.error);
+  });
+
+  // ── Branch: 0 available clouds ────────────────────────────────────────────
+
+  describe("zero available clouds", () => {
+    it("should show 'no implemented cloud providers' when agent has 0 clouds", async () => {
+      await setManifest(noCloudManifest);
+
+      await expect(cmdRun("aider", "sprite")).rejects.toThrow("process.exit");
+
+      const infos = getInfoMessages();
+      expect(infos.some((msg: string) => msg.includes("no implemented cloud providers"))).toBe(true);
+    });
+
+    it("should suggest 'spawn list' when agent has 0 clouds", async () => {
+      await setManifest(noCloudManifest);
+
+      await expect(cmdRun("aider", "hetzner")).rejects.toThrow("process.exit");
+
+      const infos = getInfoMessages();
+      expect(infos.some((msg: string) => msg.includes("spawn list"))).toBe(true);
+    });
+
+    it("should NOT show example spawn commands when agent has 0 clouds", async () => {
+      await setManifest(noCloudManifest);
+
+      await expect(cmdRun("aider", "sprite")).rejects.toThrow("process.exit");
+
+      const infos = getInfoMessages();
+      // Should not have any "spawn aider <cloud>" examples
+      expect(infos.some((msg: string) => /spawn aider \w+/.test(msg) && !msg.includes("spawn list"))).toBe(false);
+    });
+
+    it("should show 'not yet implemented' error message", async () => {
+      await setManifest(noCloudManifest);
+
+      await expect(cmdRun("aider", "sprite")).rejects.toThrow("process.exit");
+
+      const errors = getErrorMessages();
+      expect(errors.some((msg: string) => msg.includes("not yet implemented"))).toBe(true);
+    });
+
+    it("should include agent and cloud display names in error", async () => {
+      await setManifest(noCloudManifest);
+
+      await expect(cmdRun("aider", "sprite")).rejects.toThrow("process.exit");
+
+      const errors = getErrorMessages();
+      expect(errors.some((msg: string) => msg.includes("Aider") && msg.includes("Sprite"))).toBe(true);
+    });
+  });
+
+  // ── Branch: 1-3 available clouds (show all as examples) ───────────────────
+
+  describe("1-3 available clouds (show all examples)", () => {
+    it("should show 2 example commands when agent has 2 clouds", async () => {
+      await setManifest(twoCloudManifest);
+
+      await expect(cmdRun("aider", "broken")).rejects.toThrow("process.exit");
+
+      const infos = getInfoMessages();
+      const exampleLines = infos.filter((msg: string) => msg.includes("spawn aider"));
+      // Should show exactly 2 cloud alternatives
+      expect(exampleLines.length).toBe(2);
+      expect(infos.some((msg: string) => msg.includes("spawn aider sprite"))).toBe(true);
+      expect(infos.some((msg: string) => msg.includes("spawn aider hetzner"))).toBe(true);
+    });
+
+    it("should show cloud count with correct singular/plural", async () => {
+      await setManifest(twoCloudManifest);
+
+      await expect(cmdRun("aider", "broken")).rejects.toThrow("process.exit");
+
+      const infos = getInfoMessages();
+      expect(infos.some((msg: string) => msg.includes("2 clouds"))).toBe(true);
+    });
+
+    it("should show 3 examples at boundary (exactly 3 clouds)", async () => {
+      await setManifest(threeCloudManifest);
+
+      await expect(cmdRun("aider", "broken")).rejects.toThrow("process.exit");
+
+      const infos = getInfoMessages();
+      const exampleLines = infos.filter((msg: string) => msg.includes("spawn aider"));
+      expect(exampleLines.length).toBe(3);
+      expect(infos.some((msg: string) => msg.includes("spawn aider sprite"))).toBe(true);
+      expect(infos.some((msg: string) => msg.includes("spawn aider hetzner"))).toBe(true);
+      expect(infos.some((msg: string) => msg.includes("spawn aider vultr"))).toBe(true);
+    });
+
+    it("should NOT show 'see all' hint when exactly 3 clouds", async () => {
+      await setManifest(threeCloudManifest);
+
+      await expect(cmdRun("aider", "broken")).rejects.toThrow("process.exit");
+
+      const infos = getInfoMessages();
+      // Should NOT have the "Run spawn X to see all" message
+      expect(infos.some((msg: string) => msg.includes("to see all"))).toBe(false);
+    });
+
+    it("should use singular 'cloud' for exactly 1 cloud", async () => {
+      // Modify manifest to have only 1 implemented cloud
+      const oneCloudManifest = {
+        agents: noCloudManifest.agents,
+        clouds: noCloudManifest.clouds,
+        matrix: {
+          "sprite/aider": "implemented",
+          "hetzner/aider": "missing",
+        },
+      };
+      await setManifest(oneCloudManifest);
+
+      await expect(cmdRun("aider", "hetzner")).rejects.toThrow("process.exit");
+
+      const infos = getInfoMessages();
+      // Should say "1 cloud" (singular) not "1 clouds"
+      expect(infos.some((msg: string) => msg.includes("1 cloud") && !msg.includes("1 clouds"))).toBe(true);
+    });
+  });
+
+  // ── Branch: >3 available clouds (show first 3, then "see all") ────────────
+
+  describe("more than 3 available clouds (truncated with see-all hint)", () => {
+    it("should show only 3 example commands when agent has 4 clouds", async () => {
+      await setManifest(fourCloudManifest);
+
+      await expect(cmdRun("aider", "broken")).rejects.toThrow("process.exit");
+
+      const infos = getInfoMessages();
+      const exampleLines = infos.filter((msg: string) =>
+        /spawn aider (sprite|hetzner|vultr|linode)/.test(msg)
+      );
+      expect(exampleLines.length).toBe(3);
+    });
+
+    it("should show 'see all' hint when agent has 4 clouds", async () => {
+      await setManifest(fourCloudManifest);
+
+      await expect(cmdRun("aider", "broken")).rejects.toThrow("process.exit");
+
+      const infos = getInfoMessages();
+      expect(infos.some((msg: string) => msg.includes("to see all") && msg.includes("4"))).toBe(true);
+    });
+
+    it("should include 'spawn aider' in the see-all hint", async () => {
+      await setManifest(fourCloudManifest);
+
+      await expect(cmdRun("aider", "broken")).rejects.toThrow("process.exit");
+
+      const infos = getInfoMessages();
+      const seeAllLine = infos.find((msg: string) => msg.includes("to see all"));
+      expect(seeAllLine).toBeDefined();
+      expect(seeAllLine!).toContain("spawn aider");
+    });
+
+    it("should show only 3 example commands when agent has 5 clouds", async () => {
+      await setManifest(manyCloudManifest);
+
+      await expect(cmdRun("claude", "broken")).rejects.toThrow("process.exit");
+
+      const infos = getInfoMessages();
+      const exampleLines = infos.filter((msg: string) =>
+        /spawn claude (sprite|hetzner|vultr|linode|digitalocean)/.test(msg)
+      );
+      expect(exampleLines.length).toBe(3);
+    });
+
+    it("should show 'see all 5 options' when agent has 5 clouds", async () => {
+      await setManifest(manyCloudManifest);
+
+      await expect(cmdRun("claude", "broken")).rejects.toThrow("process.exit");
+
+      const infos = getInfoMessages();
+      expect(infos.some((msg: string) => msg.includes("to see all") && msg.includes("5"))).toBe(true);
+    });
+
+    it("should show cloud count with plural 'clouds' for 5", async () => {
+      await setManifest(manyCloudManifest);
+
+      await expect(cmdRun("claude", "broken")).rejects.toThrow("process.exit");
+
+      const infos = getInfoMessages();
+      expect(infos.some((msg: string) => msg.includes("5 clouds"))).toBe(true);
+    });
+
+    it("should still show 'not yet implemented' error for >3 clouds", async () => {
+      await setManifest(manyCloudManifest);
+
+      await expect(cmdRun("claude", "broken")).rejects.toThrow("process.exit");
+
+      const errors = getErrorMessages();
+      expect(errors.some((msg: string) => msg.includes("not yet implemented"))).toBe(true);
+    });
+
+    it("should include agent and cloud names in error for >3 clouds", async () => {
+      await setManifest(manyCloudManifest);
+
+      await expect(cmdRun("claude", "broken")).rejects.toThrow("process.exit");
+
+      const errors = getErrorMessages();
+      expect(errors.some((msg: string) => msg.includes("Claude Code") && msg.includes("Broken Cloud"))).toBe(true);
+    });
+
+    it("should show 0 implemented clouds and no examples for aider on broken-cloud manifest", async () => {
+      await setManifest(manyCloudManifest);
+
+      await expect(cmdRun("aider", "broken")).rejects.toThrow("process.exit");
+
+      const infos = getInfoMessages();
+      // aider has 0 implemented clouds in this manifest
+      expect(infos.some((msg: string) => msg.includes("no implemented cloud providers"))).toBe(true);
+      expect(infos.some((msg: string) => msg.includes("spawn list"))).toBe(true);
+    });
+  });
+
+  // ── Error message content ─────────────────────────────────────────────────
+
+  describe("error message formatting", () => {
+    it("should show agent display name (not key) in error", async () => {
+      await setManifest(manyCloudManifest);
+
+      await expect(cmdRun("claude", "broken")).rejects.toThrow("process.exit");
+
+      const errors = getErrorMessages();
+      // Should use "Claude Code" not "claude"
+      expect(errors.some((msg: string) => msg.includes("Claude Code"))).toBe(true);
+    });
+
+    it("should show cloud display name (not key) in error", async () => {
+      await setManifest(manyCloudManifest);
+
+      await expect(cmdRun("claude", "broken")).rejects.toThrow("process.exit");
+
+      const errors = getErrorMessages();
+      // Should use "Broken Cloud" not "broken"
+      expect(errors.some((msg: string) => msg.includes("Broken Cloud"))).toBe(true);
+    });
+
+    it("should call process.exit(1) for unimplemented combo", async () => {
+      await setManifest(manyCloudManifest);
+
+      await expect(cmdRun("claude", "broken")).rejects.toThrow("process.exit");
+
+      expect(processExitSpy).toHaveBeenCalledWith(1);
+    });
+  });
+
+  // ── Boundary: exactly at the 3-cloud threshold ────────────────────────────
+
+  describe("threshold boundary (3 vs 4 clouds)", () => {
+    it("should NOT truncate at exactly 3 clouds", async () => {
+      await setManifest(threeCloudManifest);
+
+      await expect(cmdRun("aider", "broken")).rejects.toThrow("process.exit");
+
+      const infos = getInfoMessages();
+      // All 3 should be shown as examples
+      expect(infos.filter((msg: string) => msg.includes("spawn aider")).length).toBe(3);
+      // No truncation hint
+      expect(infos.some((msg: string) => msg.includes("to see all"))).toBe(false);
+    });
+
+    it("should truncate at exactly 4 clouds", async () => {
+      await setManifest(fourCloudManifest);
+
+      await expect(cmdRun("aider", "broken")).rejects.toThrow("process.exit");
+
+      const infos = getInfoMessages();
+      // Only 3 examples shown
+      const exampleLines = infos.filter((msg: string) =>
+        /spawn aider (sprite|hetzner|vultr|linode)/.test(msg)
+      );
+      expect(exampleLines.length).toBe(3);
+      // Truncation hint present
+      expect(infos.some((msg: string) => msg.includes("to see all") && msg.includes("4"))).toBe(true);
+    });
+  });
+});