fix(bar): probe IPv6 loopback when detecting a running CCS server

'ccs config' starts the web-server on host 'localhost', which macOS
resolves to ::1, so a reuse probe limited to 127.0.0.1 missed the most
common already-running server and launch started a redundant second
instance. Each candidate port is now probed on 127.0.0.1 first and then
[::1]; an IPv6 hit writes the bracketed-literal baseUrl into bar.json,
which URLSession in the Swift app resolves correctly.

src/commands/bar/launch-subcommand.ts

@@ -77,21 +77,26 @@ export function resolveBarPort(ccsDir: string): number | null {
 // ---------------------------------------------------------------------------
 
 /**
- * Probe candidate ports for a running CCS server on 127.0.0.1.
+ * Probe candidate ports for a running CCS server.
+ *
+ * Both IPv4 (127.0.0.1) and IPv6 (::1) loopback addresses are probed for
+ * each port. This is necessary because `ccs config` starts the server with
+ * host 'localhost', which macOS resolves to ::1 — an IPv4-only probe would
+ * miss that server and start a redundant second instance.
+ *
+ * Probe order per port: 127.0.0.1 first, then [::1]. First 200 wins.
  * The bar.json port (if present) is checked first so a previously-used port
  * gets priority. Short timeouts prevent hanging the launch flow.
  */
 export async function defaultFindRunningServer(ccsDir: string): Promise<DashboardInfo | null> {
   const { request } = await import('undici');
 
-  const barJsonPort = resolveBarPort(ccsDir);
-  const base = [3000, 3001, 3002, 8000, 8080];
-  const candidates: number[] =
-    barJsonPort !== null ? [barJsonPort, ...base.filter((p) => p !== barJsonPort)] : base;
-
-  for (const port of candidates) {
+  /**
+   * Probe a single URL. Returns true on HTTP 200, false on any other status
+   * or error (connection refused, timeout, etc.).
+   */
+  async function probe(url: string): Promise<boolean> {
     try {
-      const url = `http://127.0.0.1:${port}/api/bar/summary`;
       const { statusCode, body } = await request(url, {
         method: 'GET',
         headersTimeout: 1500,
@@ -101,11 +106,26 @@ export async function defaultFindRunningServer(ccsDir: string): Promise<Dashboar
       // body.dump() is not available in Bun's undici shim; body.text() works
       // cross-runtime and fully consumes the response stream.
       await body.text();
-      if (statusCode === 200) {
-        return { port, baseUrl: `http://127.0.0.1:${port}` };
-      }
+      return statusCode === 200;
     } catch {
-      // Connection refused, timeout, or any other error → try next candidate.
+      return false;
+    }
+  }
+
+  const barJsonPort = resolveBarPort(ccsDir);
+  const base = [3000, 3001, 3002, 8000, 8080];
+  const candidates: number[] =
+    barJsonPort !== null ? [barJsonPort, ...base.filter((p) => p !== barJsonPort)] : base;
+
+  for (const port of candidates) {
+    // Probe IPv4 loopback first (common for explicitly-bound servers).
+    if (await probe(`http://127.0.0.1:${port}/api/bar/summary`)) {
+      return { port, baseUrl: `http://127.0.0.1:${port}` };
+    }
+    // Probe IPv6 loopback — `ccs config` binds 'localhost' which resolves to
+    // ::1 on macOS, so this is the common case for a running CCS server.
+    if (await probe(`http://[::1]:${port}/api/bar/summary`)) {
+      return { port, baseUrl: `http://[::1]:${port}` };
     }
   }
   return null;

tests/unit/commands/bar-command.test.ts

@@ -1738,6 +1738,71 @@ describe('defaultFindRunningServer (GH-1500)', () => {
       expect(result).toBeNull();
     }
   });
+
+  it('detects a real HTTP server responding 200 on /api/bar/summary bound to ::1 only', async () => {
+    const http = await import('http');
+    const net = await import('net');
+
+    // Guard: check if IPv6 loopback is available on this runner.
+    // Some CI environments disable IPv6; we skip gracefully rather than fail.
+    let ipv6Available = false;
+    await new Promise<void>((resolve) => {
+      const probe = net.createServer();
+      probe.once('error', () => {
+        // EADDRNOTAVAIL or EAFNOSUPPORT → no IPv6 on this host
+        console.log('[i] Skipping IPv6 loopback test: ::1 not available on this runner');
+        resolve();
+      });
+      probe.listen(0, '::1', () => {
+        ipv6Available = true;
+        probe.close(() => resolve());
+      });
+    });
+
+    if (!ipv6Available) {
+      return;
+    }
+
+    // Start an ephemeral HTTP server bound exclusively to ::1.
+    // This simulates `ccs config` starting the web-server with host 'localhost'
+    // on macOS, where 'localhost' resolves to ::1.
+    const server = http.createServer((_req, res) => {
+      res.writeHead(200, { 'Content-Type': 'application/json' });
+      res.end('{}');
+    });
+    await new Promise<void>((resolve) => server.listen(0, '::1', resolve));
+    const addr = server.address() as { port: number };
+    const livePort = addr.port;
+
+    // Seed bar.json with the live port so it is checked first.
+    const ccsDir = path.join(tempHome, '.ccs');
+    fs.mkdirSync(ccsDir, { recursive: true });
+    fs.writeFileSync(
+      path.join(ccsDir, 'bar.json'),
+      JSON.stringify({ port: livePort, baseUrl: `http://[::1]:${livePort}`, authMode: 'loopback' })
+    );
+
+    moduleSeq++;
+    const mod = await import(
+      `../../../src/commands/bar/launch-subcommand?test=${Date.now()}-${moduleSeq}`
+    );
+    const { defaultFindRunningServer } = mod as {
+      defaultFindRunningServer: (ccsDir: string) => Promise<{ port: number; baseUrl: string } | null>;
+    };
+
+    let result: { port: number; baseUrl: string } | null = null;
+    try {
+      result = await defaultFindRunningServer(ccsDir);
+    } finally {
+      await new Promise<void>((resolve) => server.close(() => resolve()));
+    }
+
+    expect(result).not.toBeNull();
+    expect(result?.port).toBe(livePort);
+    // baseUrl must use bracketed IPv6 literal — valid in URLs per RFC 2732;
+    // the Swift app reads this verbatim and URLSession handles bracketed IPv6 hosts.
+    expect(result?.baseUrl).toBe(`http://[::1]:${livePort}`);
+  });
 });
 
 // ---------------------------------------------------------------------------