refactor(utils): extract killWithEscalation to shared process-utils

- Move killWithEscalation to src/utils/process-utils.ts (DRY)
- Fix handleCancel to use exitCode === null and killWithEscalation
- Fix import ordering in both oauth-process.ts and headless-executor.ts

src/cliproxy/auth/oauth-process.ts

@@ -6,20 +6,8 @@
  */
 
 import { spawn, ChildProcess } from 'child_process';
-
-/**
- * Kill process with SIGTERM, escalating to SIGKILL if it doesn't exit
- */
-function killWithEscalation(proc: ChildProcess, gracePeriodMs = 3000): void {
-  proc.kill('SIGTERM');
-  const timer = setTimeout(() => {
-    if (proc.exitCode === null) {
-      proc.kill('SIGKILL');
-    }
-  }, gracePeriodMs);
-  proc.once('exit', () => clearTimeout(timer));
-}
 import { ok, fail, info, warn } from '../../utils/ui';
+import { killWithEscalation } from '../../utils/process-utils';
 import { tryKiroImport } from './kiro-import';
 import { CLIProxyProvider } from '../types';
 import { AccountInfo } from '../account-manager';
@@ -371,9 +359,9 @@ export function executeOAuthProcess(options: OAuthProcessOptions): Promise<Accou
 
     // Listen for external cancel signal
     const handleCancel = (cancelledSessionId: string) => {
-      if (cancelledSessionId === state.sessionId && authProcess && !authProcess.killed) {
+      if (cancelledSessionId === state.sessionId && authProcess && authProcess.exitCode === null) {
         log('Session cancelled externally');
-        authProcess.kill('SIGTERM');
+        killWithEscalation(authProcess);
       }
     };
     authSessionEvents.on('session:cancelled', handleCancel);

src/delegation/headless-executor.ts

@@ -5,21 +5,9 @@
  * Spawns claude with -p flag for single-turn execution
  */
 
-import { spawn, ChildProcess } from 'child_process';
-
-/**
- * Kill process with SIGTERM, escalating to SIGKILL if it doesn't exit
- */
-function killWithEscalation(proc: ChildProcess, gracePeriodMs = 3000): void {
-  proc.kill('SIGTERM');
-  const timer = setTimeout(() => {
-    if (proc.exitCode === null) {
-      proc.kill('SIGKILL');
-    }
-  }, gracePeriodMs);
-  proc.once('exit', () => clearTimeout(timer));
-}
+import { spawn } from 'child_process';
 import * as path from 'path';
+import { killWithEscalation } from '../utils/process-utils';
 import * as fs from 'fs';
 import { SessionManager } from './session-manager';
 import { SettingsParser } from './settings-parser';

src/utils/process-utils.ts

@@ -0,0 +1,20 @@
+/**
+ * Process management utilities
+ */
+
+import { ChildProcess } from 'child_process';
+
+/**
+ * Kill process with SIGTERM, escalating to SIGKILL if it doesn't exit.
+ * Uses exitCode === null (not proc.killed) to check if process is still running,
+ * since proc.killed only indicates a signal was sent, not that the process exited.
+ */
+export function killWithEscalation(proc: ChildProcess, gracePeriodMs = 3000): void {
+  proc.kill('SIGTERM');
+  const timer = setTimeout(() => {
+    if (proc.exitCode === null) {
+      proc.kill('SIGKILL');
+    }
+  }, gracePeriodMs);
+  proc.once('exit', () => clearTimeout(timer));
+}