fix(ci-setup): probe the resolved --port for availability

detectEnvironment ran checkPortAvailable(4747) eagerly, before options
were parsed, and the result was printed as a hardcoded "Port 4747:
available" line — wrong/irrelevant whenever the user passed a different
--port. Export checkPortAvailable, drop the eager hardcoded probe (and the
now-unused portAvailable field from DetectResult), and probe resolved.port
after option resolution, reporting the actual port. This also removes a
latent real-socket bind on 4747 from the default unit-test path.

Co-Authored-By: Claude Opus 4.8 (1M context) <noreply@anthropic.com>

gitnexus/src/cli/ci-setup.ts

@@ -12,7 +12,7 @@
 
 import fs from 'fs/promises';
 import path from 'path';
-import { detectEnvironment } from './ci-setup/detect.js';
+import { detectEnvironment, checkPortAvailable } from './ci-setup/detect.js';
 import { resolveOptions } from './ci-setup/prompts.js';
 import { generateFiles } from './ci-setup/templates.js';
 import type { CiSetupOptions, CiSetupResult, GeneratedFile } from './ci-setup/types.js';
@@ -68,9 +68,6 @@ export const ciSetupCommand = async (options?: {
   if (detect.hasDocker) {
     console.log('   ✓ Docker: docker-compose or Dockerfile found');
   }
-  console.log(
-    `   ${detect.portAvailable ? '✓' : '⚠'} Port 4747: ${detect.portAvailable ? 'available' : 'in use (serve may already be running)'}`,
-  );
   console.log('   ⚠ License: PolyForm-Noncommercial — confirm non-commercial use\n');
 
   // Parse and validate options from commander flags. An explicitly-passed but
@@ -105,6 +102,14 @@ export const ciSetupCommand = async (options?: {
   }
 
   const resolved = await resolveOptions(detect, partial);
+
+  // Probe the *resolved* port (now that --port / prompts are settled) rather
+  // than a hardcoded default at detection time.
+  const portAvailable = await checkPortAvailable(resolved.port);
+  console.log(
+    `   ${portAvailable ? '✓' : '⚠'} Port ${resolved.port}: ${portAvailable ? 'available' : 'in use (serve may already be running)'}`,
+  );
+
   const files = generateFiles(resolved, detect);
 
   const result: CiSetupResult = { generated: [], skipped: [], errors: [] };

gitnexus/src/cli/ci-setup/detect.ts

@@ -105,7 +105,12 @@ async function detectPrimaryLanguage(repoRoot: string): Promise<string> {
   return top;
 }
 
-function checkPortAvailable(port: number): Promise<boolean> {
+/**
+ * Whether `port` can be bound on the loopback interface. Exported so the caller
+ * can probe the *resolved* --port (known only after option parsing) rather than
+ * a hardcoded default at detection time.
+ */
+export function checkPortAvailable(port: number): Promise<boolean> {
   return new Promise((resolve) => {
     const server = net.createServer();
     server.once('error', () => resolve(false));
@@ -124,17 +129,15 @@ export async function detectEnvironment(cwd: string): Promise<DetectResult> {
       gitRoot: null,
       detectedCi: null,
       hasDocker: false,
-      portAvailable: false,
       primaryLanguage: 'Unknown',
     };
   }
 
-  const [detectedCi, hasDocker, portAvailable, primaryLanguage] = await Promise.all([
+  const [detectedCi, hasDocker, primaryLanguage] = await Promise.all([
     detectCiSystem(gitRoot),
     detectDocker(gitRoot),
-    checkPortAvailable(4747),
     detectPrimaryLanguage(gitRoot),
   ]);
 
-  return { gitRoot, detectedCi, hasDocker, portAvailable, primaryLanguage };
+  return { gitRoot, detectedCi, hasDocker, primaryLanguage };
 }

gitnexus/src/cli/ci-setup/types.ts

@@ -19,7 +19,6 @@ export interface DetectResult {
   gitRoot: string | null;
   detectedCi: CiSystem | null;
   hasDocker: boolean;
-  portAvailable: boolean;
   primaryLanguage: string;
 }
 

gitnexus/test/unit/ci-setup-templates.test.ts

@@ -7,7 +7,6 @@ const DEFAULT_DETECT: DetectResult = {
   gitRoot: '/repo',
   detectedCi: 'github-actions',
   hasDocker: true,
-  portAvailable: true,
   primaryLanguage: 'TypeScript',
 };
 

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

@@ -231,6 +231,28 @@ describe('ciSetupCommand', () => {
     const entries = await fs.readdir(tempDir);
     expect(entries).toHaveLength(0);
   });
+
+  it('probes the resolved --port for availability (not a hardcoded 4747)', async () => {
+    vi.resetModules();
+    vi.doMock('../../src/cli/ci-setup/detect.js', async () => {
+      const actual = await vi.importActual<typeof import('../../src/cli/ci-setup/detect.js')>(
+        '../../src/cli/ci-setup/detect.js',
+      );
+      return { ...actual, checkPortAvailable: vi.fn(() => Promise.resolve(true)) };
+    });
+    const detectMod = await import('../../src/cli/ci-setup/detect.js');
+    const { ciSetupCommand } = await import('../../src/cli/ci-setup.js');
+    await ciSetupCommand({
+      ci: 'github-actions',
+      deploy: 'docker',
+      auth: 'token',
+      port: '4748',
+      dryRun: true,
+      outputDir: tempDir,
+    });
+    expect(vi.mocked(detectMod.checkPortAvailable)).toHaveBeenCalledWith(4748);
+    vi.doUnmock('../../src/cli/ci-setup/detect.js');
+  });
 });
 
 describe('resolveOptions (U1: interactive prompts reachable)', () => {
@@ -238,7 +260,6 @@ describe('resolveOptions (U1: interactive prompts reachable)', () => {
     gitRoot: '/tmp/repo',
     detectedCi: null,
     hasDocker: false,
-    portAvailable: true,
     primaryLanguage: 'TypeScript',
   };
   let originalTTY: boolean | undefined;