refactor(cli): centralize daemon errno parsing and add utility tests

What changed:
- extracted shared readNodeErrnoCode helper in local daemon process control code
- updated isProcessRunning and signalProcess to use the shared helper
- added packages/cli/tests/18-local-daemon-utils.test.ts covering resolveTcpHostFromListen cases (numeric, host:port, unix sockets, empty/non-host)

Why:
- removes duplicated low-level error-shape branching and keeps errno handling consistent in one place
- adds deterministic coverage for pure listen parsing logic without depending on daemon runtime state

Accomplishments for next agent:
- this area now has a focused utility test entry that runs fast and is independent of daemon availability
- full workspace typecheck is clean after this change

Challenges / notes for next agent:
- packages/cli/tests/03-daemon.test.ts can be environment-sensitive when a daemon is already running (baseline in this workspace did not reliably represent daemon not running)
- existing unstaged change remains in scripts/codex-refactor-loop.sh and was intentionally left untouched

packages/cli/src/commands/daemon/local-daemon.ts

@@ -169,12 +169,20 @@ function sleep(ms: number): Promise<void> {
   })
 }
 
+function readNodeErrnoCode(error: unknown): string | undefined {
+  if (typeof error !== 'object' || error === null || !('code' in error)) {
+    return undefined
+  }
+
+  return typeof error.code === 'string' ? error.code : undefined
+}
+
 function isProcessRunning(pid: number): boolean {
   try {
     process.kill(pid, 0)
     return true
   } catch (err) {
-    const code = typeof err === 'object' && err && 'code' in err ? (err as { code?: string }).code : undefined
+    const code = readNodeErrnoCode(err)
     if (code === 'EPERM') {
       return true
     }
@@ -187,7 +195,7 @@ function signalProcess(pid: number, signal: NodeJS.Signals): boolean {
     process.kill(pid, signal)
     return true
   } catch (err) {
-    const code = typeof err === 'object' && err && 'code' in err ? (err as { code?: string }).code : undefined
+    const code = readNodeErrnoCode(err)
     if (code === 'ESRCH') {
       return false
     }

packages/cli/tests/18-local-daemon-utils.test.ts

@@ -0,0 +1,43 @@
+#!/usr/bin/env npx tsx
+
+/**
+ * Phase 18: Local daemon utility tests.
+ *
+ * Tests pure helpers that do not require a running daemon.
+ */
+
+import assert from 'node:assert'
+import { resolveTcpHostFromListen } from '../src/commands/daemon/local-daemon.js'
+
+console.log('=== Local Daemon Utility Helpers ===\n')
+
+{
+  console.log('Test 1: resolves numeric listen values to localhost host:port')
+  assert.strictEqual(resolveTcpHostFromListen('6767'), '127.0.0.1:6767')
+  assert.strictEqual(resolveTcpHostFromListen('  7777  '), '127.0.0.1:7777')
+  console.log('✓ resolves numeric listen values\n')
+}
+
+{
+  console.log('Test 2: preserves explicit host:port listen values')
+  assert.strictEqual(resolveTcpHostFromListen('localhost:6767'), 'localhost:6767')
+  assert.strictEqual(resolveTcpHostFromListen('0.0.0.0:8080'), '0.0.0.0:8080')
+  console.log('✓ preserves explicit host:port values\n')
+}
+
+{
+  console.log('Test 3: rejects unix socket listen values')
+  assert.strictEqual(resolveTcpHostFromListen('/tmp/paseo.sock'), null)
+  assert.strictEqual(resolveTcpHostFromListen('unix:///tmp/paseo.sock'), null)
+  console.log('✓ rejects unix socket listen values\n')
+}
+
+{
+  console.log('Test 4: rejects empty and non-host listen values')
+  assert.strictEqual(resolveTcpHostFromListen(''), null)
+  assert.strictEqual(resolveTcpHostFromListen('   '), null)
+  assert.strictEqual(resolveTcpHostFromListen('localhost'), null)
+  console.log('✓ rejects empty and non-host listen values\n')
+}
+
+console.log('=== All local daemon utility tests passed ===')