feat(setup): add Factory Droid (MCP + skills) to gitnexus setup

Register 'droid' in the editor-targets abstraction so `gitnexus setup -c droid`
writes the MCP server to ~/.factory/mcp.json and installs skills to
~/.factory/skills/ from the single canonical skills/ source (no per-editor
copies). uninstall.ts is target-driven, so removal is covered automatically.
Adds unit + round-trip coverage.

gitnexus/src/cli/editor-targets.ts

@@ -26,7 +26,8 @@ export type EditorId =
   | 'opencode'
   | 'codebuddy'
   | 'qoder'
-  | 'codex';
+  | 'codex'
+  | 'droid';
 
 /** An editor whose MCP config is a JSONC document (server keyed by name). */
 export interface McpJsoncTarget {
@@ -145,6 +146,15 @@ export function getEditorTargets(home: string = os.homedir()): EditorTargets {
       file: path.join(home, '.qoder.json'),
       keyPath: ['mcpServers', 'gitnexus'],
     },
+    {
+      id: 'droid',
+      label: 'Factory Droid',
+      // Factory's user-scope MCP config (https://docs.factory.ai/cli/configuration/mcp).
+      // Same `mcpServers` object shape as Cursor/Claude; user config takes
+      // precedence over project-level .factory/mcp.json.
+      file: path.join(home, '.factory', 'mcp.json'),
+      keyPath: ['mcpServers', 'gitnexus'],
+    },
   ];
 
   const codex: CodexMcpTarget = {
@@ -169,6 +179,9 @@ export function getEditorTargets(home: string = os.homedir()): EditorTargets {
     { id: 'qoder', label: 'Qoder', dir: path.join(home, '.qoder', 'skills') },
     // Codex reads skills from ~/.agents/skills (not ~/.codex).
     { id: 'codex', label: 'Codex', dir: path.join(home, '.agents', 'skills') },
+    // Factory Droid reads user-scope skills from ~/.factory/skills/{name}/SKILL.md
+    // (https://docs.factory.ai/cli/configuration/skills).
+    { id: 'droid', label: 'Factory Droid', dir: path.join(home, '.factory', 'skills') },
   ];
 
   const hooks: HookTarget[] = [

gitnexus/src/cli/index.ts

@@ -24,7 +24,7 @@ program.name('gitnexus').description('GitNexus local CLI and MCP server').versio
 program
   .command('setup')
   .description(
-    'One-time setup: configure MCP for Cursor, Claude Code, Antigravity, OpenCode, CodeBuddy, Qoder, Codex',
+    'One-time setup: configure MCP for Cursor, Claude Code, Antigravity, OpenCode, CodeBuddy, Qoder, Codex, Factory Droid',
   )
   .option(
     '-c, --coding-agent <agents>',

gitnexus/src/cli/setup.ts

@@ -95,6 +95,7 @@ const CODING_AGENT_IDS = {
   codebuddy: 'codebuddy',
   qoder: 'qoder',
   codex: 'codex',
+  droid: 'droid',
 } as const satisfies Record<EditorId, EditorId>;
 const SUPPORTED_CODING_AGENTS = Object.values(CODING_AGENT_IDS);
 
@@ -951,6 +952,59 @@ async function installQoderSkills(result: SetupResult): Promise<void> {
   }
 }
 
+/**
+ * Configure the GitNexus MCP server for Factory Droid.
+ *
+ * Factory stores user-scope MCP config in ~/.factory/mcp.json using the same
+ * `{ mcpServers: { <name>: {...} } }` JSONC shape as Cursor/Claude
+ * (https://docs.factory.ai/cli/configuration/mcp), so we reuse mergeJsoncFile
+ * rather than shelling out to `droid mcp add` — that keeps setup working even
+ * when the `droid` binary isn't on PATH.
+ */
+async function setupDroid(result: SetupResult): Promise<void> {
+  const factoryDir = path.join(os.homedir(), '.factory');
+  if (!(await dirExists(factoryDir))) {
+    result.skipped.push('Factory Droid (not installed)');
+    return;
+  }
+
+  const { file: mcpPath, keyPath } = mcpTarget('droid');
+  try {
+    const ok = await mergeJsoncFile(mcpPath, keyPath, getMcpEntry());
+    if (ok) {
+      result.configured.push('Factory Droid');
+    } else {
+      result.errors.push(
+        'Factory Droid: mcp.json is corrupt — skipping to preserve existing content',
+      );
+    }
+  } catch (err: any) {
+    result.errors.push(`Factory Droid: ${err.message}`);
+  }
+}
+
+/**
+ * Install global Factory Droid skills to ~/.factory/skills/{name}/SKILL.md
+ * (https://docs.factory.ai/cli/configuration/skills — same SKILL.md layout as
+ * Claude Code).
+ */
+async function installDroidSkills(result: SetupResult): Promise<void> {
+  const factoryDir = path.join(os.homedir(), '.factory');
+  if (!(await dirExists(factoryDir))) return;
+
+  const skillsDir = skillTarget('droid').dir;
+  try {
+    const installed = await installSkillsTo(skillsDir);
+    if (installed.length > 0) {
+      result.configured.push(
+        `Factory Droid skills (${installed.length} skills → ~/.factory/skills/)`,
+      );
+    }
+  } catch (err: any) {
+    result.errors.push(`Factory Droid skills: ${err.message}`);
+  }
+}
+
 /**
  * Build a TOML section for Codex MCP config (~/.codex/config.toml).
  */
@@ -1197,6 +1251,7 @@ export const setupCommand = async (options?: { codingAgent?: string[] | string }
   if (selected.has('codebuddy')) await setupCodeBuddy(result);
   if (selected.has('qoder')) await setupQoder(result);
   if (selected.has('codex')) await setupCodex(result);
+  if (selected.has('droid')) await setupDroid(result);
 
   // Install global skills for platforms that support them
   if (selected.has('claude')) {
@@ -1215,6 +1270,10 @@ export const setupCommand = async (options?: { codingAgent?: string[] | string }
     await installCodexSkills(result);
     await installClaudeSchemaHooks(result, 'codex');
   }
+  // MCP + skills only. Factory hooks (Execute matcher, PostToolUse) ship in the
+  // standalone gitnexus-factory-plugin instead of the setup path — add a droid
+  // hook target + adapter here if setup-installed hooks are wanted.
+  if (selected.has('droid')) await installDroidSkills(result);
 
   // Print results
   if (result.configured.length > 0) {

gitnexus/test/integration/setup-uninstall-roundtrip.test.ts

@@ -82,7 +82,7 @@ describe('setup → uninstall round-trip', () => {
     process.env.USERPROFILE = tempHome;
 
     // Mark every editor as "installed" so setup configures all of them.
-    for (const dir of ['.cursor', '.claude', '.codex', '.codebuddy', '.qoder']) {
+    for (const dir of ['.cursor', '.claude', '.codex', '.codebuddy', '.qoder', '.factory']) {
       await fs.mkdir(path.join(tempHome, dir), { recursive: true });
     }
     await fs.mkdir(path.join(tempHome, '.gemini', 'antigravity'), { recursive: true });

gitnexus/test/unit/setup-selection.test.ts

@@ -101,7 +101,7 @@ describe('setupCommand coding-agent selection', () => {
     expect(process.exitCode).toBe(1);
     expect(stderr).toHaveBeenCalledWith(
       expect.stringContaining(
-        'Valid values: cursor, claude, antigravity, opencode, codebuddy, qoder, codex',
+        'Valid values: cursor, claude, antigravity, opencode, codebuddy, qoder, codex, droid',
       ),
     );
     await expect(

gitnexus/test/unit/setup.test.ts

@@ -715,6 +715,79 @@ describe('setupQoder', () => {
   });
 });
 
+describe('setupDroid (Factory)', () => {
+  let tempHome: string;
+  let originalHome: string | undefined;
+  let originalUserProfile: string | undefined;
+
+  const configPath = () => path.join(tempHome, '.factory', 'mcp.json');
+
+  beforeEach(async () => {
+    vi.resetModules();
+    vi.clearAllMocks();
+
+    originalHome = process.env.HOME;
+    originalUserProfile = process.env.USERPROFILE;
+    tempHome = await fs.mkdtemp(path.join(os.tmpdir(), 'gn-droid-setup-'));
+    process.env.HOME = tempHome;
+    process.env.USERPROFILE = tempHome;
+
+    // Only create ~/.factory so other editors skip and don't pollute assertions.
+    await fs.mkdir(path.join(tempHome, '.factory'), { recursive: true });
+
+    vi.spyOn(console, 'log').mockImplementation(() => {});
+  });
+
+  afterEach(async () => {
+    vi.restoreAllMocks();
+    process.env.HOME = originalHome;
+    process.env.USERPROFILE = originalUserProfile;
+    await fs.rm(tempHome, { recursive: true, force: true });
+  });
+
+  it('writes the MCP entry to ~/.factory/mcp.json under mcpServers', async () => {
+    const { setupCommand } = await import('../../src/cli/setup.js');
+    await setupCommand();
+
+    const config = JSON.parse(await fs.readFile(configPath(), 'utf-8'));
+    expect(config.mcpServers.gitnexus).toBeDefined();
+  });
+
+  it('preserves existing servers in ~/.factory/mcp.json', async () => {
+    await fs.writeFile(
+      configPath(),
+      JSON.stringify({ mcpServers: { other: { command: 'foo' } } }),
+      'utf-8',
+    );
+
+    const { setupCommand } = await import('../../src/cli/setup.js');
+    await setupCommand();
+
+    const config = JSON.parse(await fs.readFile(configPath(), 'utf-8'));
+    expect(config.mcpServers.other).toEqual({ command: 'foo' });
+    expect(config.mcpServers.gitnexus).toBeDefined();
+  });
+
+  it('skips when ~/.factory directory does not exist', async () => {
+    await fs.rm(path.join(tempHome, '.factory'), { recursive: true, force: true });
+
+    const { setupCommand } = await import('../../src/cli/setup.js');
+    await setupCommand();
+
+    await expect(fs.access(configPath())).rejects.toThrow();
+  });
+
+  it('leaves a corrupt ~/.factory/mcp.json untouched', async () => {
+    const corrupt = '{ this is not valid json !!!';
+    await fs.writeFile(configPath(), corrupt, 'utf-8');
+
+    const { setupCommand } = await import('../../src/cli/setup.js');
+    await setupCommand();
+
+    expect(await fs.readFile(configPath(), 'utf-8')).toBe(corrupt);
+  });
+});
+
 describe('Codex hooks (installClaudeSchemaHooks)', () => {
   let tempHome: string;
   let originalHome: string | undefined;