fix(progress): preserve Ctrl-C termination for shared reporter (#3614) (#3825)

Wave-assembled from PR #3825 by @javieraldape.

Co-Authored-By: Sofía González <sofiagonzalez@Sofias-MacBook-Air.local>

src/core/progress.ts

@@ -50,9 +50,10 @@ export interface ProgressReporter {
 // every live reporter. Per-instance handlers would leak listeners and interfere
 // with command-level handlers (e.g. shell-handler abort in jobs.ts).
 //
-// We never call process.exit() or swallow the signal — we just emit abort
-// events for live phases, then remove ourselves so the user's own handlers
-// (or the default Node behavior) run as usual.
+// We never call process.exit() — we just emit abort events for live phases.
+// Installing a SIGINT listener suppresses the runtime's default terminate
+// behavior, so when no command-level handler remains we re-raise SIGINT after
+// the abort event has had a tick to flush.
 
 interface LivePhase {
   reporter: PhaseState;
@@ -61,10 +62,15 @@ interface LivePhase {
 
 const liveReporters = new Set<LivePhase>();
 let signalHandlerInstalled = false;
+let hadSigintHandlersAtInstall = false;
 
 function installSignalHandler(): void {
   if (signalHandlerInstalled) return;
   signalHandlerInstalled = true;
+  // Capture command-level SIGINT ownership before our once-wrapper can be
+  // consumed by the same signal emission. A preceding once('SIGINT') listener
+  // is already gone by the time our handler runs.
+  hadSigintHandlersAtInstall = process.listenerCount('SIGINT') > 0;
 
   const onSignal = (reason: 'SIGINT' | 'SIGTERM') => {
     // Copy to array so abort() can mutate liveReporters during iteration.
@@ -76,6 +82,11 @@ function installSignalHandler(): void {
         /* best-effort */
       }
     }
+    if (reason === 'SIGINT' && !hadSigintHandlersAtInstall && process.listenerCount('SIGINT') === 0) {
+      setTimeout(() => {
+        process.kill(process.pid, 'SIGINT');
+      }, 0);
+    }
   };
 
   // once() so we don't block user handlers or double-fire.

test/progress.test.ts

@@ -1,7 +1,12 @@
 import { describe, test, expect } from 'bun:test';
-import { PassThrough } from 'node:stream';
+import { spawn, type ChildProcessByStdio } from 'node:child_process';
+import { join } from 'node:path';
+import { PassThrough, type Readable } from 'node:stream';
 import { createProgress, startHeartbeat, __liveReporterCountForTest, __signalHandlerInstalledForTest } from '../src/core/progress.ts';
 
+const REPO = join(import.meta.dir, '..');
+type SigintHarnessProcess = ChildProcessByStdio<null, Readable, Readable>;
+
 /** Collect everything a reporter writes into a string. */
 function sink(isTTY = false): { stream: PassThrough & { isTTY?: boolean }; read: () => string } {
   const s = new PassThrough() as PassThrough & { isTTY?: boolean };
@@ -18,6 +23,84 @@ function parseJsonl(raw: string): Record<string, unknown>[] {
     .map((l) => JSON.parse(l));
 }
 
+function waitForStdoutMarker(proc: SigintHarnessProcess, marker: string, readStdout: () => string, timeoutMs = 3000): Promise<void> {
+  return new Promise((resolve, reject) => {
+    const cleanup = () => {
+      clearTimeout(timeout);
+      proc.stdout.off('data', onData);
+      proc.off('exit', onExit);
+      proc.off('error', onError);
+    };
+    const onData = () => {
+      if (!readStdout().includes(marker)) return;
+      cleanup();
+      resolve();
+    };
+    const onExit = (code: number | null, signal: NodeJS.Signals | null) => {
+      cleanup();
+      reject(new Error(`child exited before ${marker}: code=${code} signal=${signal}`));
+    };
+    const onError = (err: Error) => {
+      cleanup();
+      reject(err);
+    };
+    const timeout = setTimeout(() => {
+      cleanup();
+      reject(new Error(`timed out waiting for ${marker}; stdout=${JSON.stringify(readStdout())}`));
+    }, timeoutMs);
+
+    proc.stdout.on('data', onData);
+    proc.once('exit', onExit);
+    proc.once('error', onError);
+    onData();
+  });
+}
+
+function waitForExit(proc: SigintHarnessProcess, timeoutMs = 1500): Promise<{ exited: boolean; code: number | null; signal: NodeJS.Signals | null }> {
+  return new Promise((resolve) => {
+    const cleanup = () => {
+      clearTimeout(timeout);
+      proc.off('exit', onExit);
+    };
+    const onExit = (code: number | null, signal: NodeJS.Signals | null) => {
+      cleanup();
+      resolve({ exited: true, code, signal });
+    };
+    const timeout = setTimeout(() => {
+      cleanup();
+      resolve({ exited: false, code: null, signal: null });
+    }, timeoutMs);
+    proc.once('exit', onExit);
+  });
+}
+
+async function runSigintHarness(script: string): Promise<{
+  exited: boolean;
+  code: number | null;
+  signal: NodeJS.Signals | null;
+  stdout: string;
+  stderr: string;
+}> {
+  const proc = spawn(process.execPath, ['-e', script], {
+    cwd: REPO,
+    env: { ...process.env, FORCE_COLOR: '0' },
+    stdio: ['ignore', 'pipe', 'pipe'],
+  });
+  let stdout = '';
+  let stderr = '';
+  proc.stdout.on('data', (chunk) => { stdout += chunk.toString('utf8'); });
+  proc.stderr.on('data', (chunk) => { stderr += chunk.toString('utf8'); });
+
+  await waitForStdoutMarker(proc, 'READY\n', () => stdout);
+  proc.kill('SIGINT');
+  const result = await waitForExit(proc);
+  if (!result.exited) {
+    proc.kill('SIGKILL');
+    await waitForExit(proc);
+  }
+  return { ...result, stdout, stderr };
+}
+
 describe('progress reporter', () => {
   test('auto mode: non-TTY → human-plain (NOT JSON)', () => {
     const { stream, read } = sink(false);
@@ -235,6 +318,42 @@ describe('progress reporter', () => {
     expect(__liveReporterCountForTest()).toBe(liveBefore);
   });
 
+  test('SIGINT exits a child process when the progress reporter is the only handler', async () => {
+    const result = await runSigintHarness(`
+      const { createProgress } = await import('./src/core/progress.ts');
+      const progress = createProgress({ mode: 'json' });
+      progress.start('sigint_repro', 1);
+      process.stdout.write('READY\\n');
+      setInterval(() => {}, 1000);
+    `);
+
+    expect(result.exited).toBe(true);
+    expect(result.signal === 'SIGINT' || result.code === 130).toBe(true);
+    expect(result.stderr).toContain('"event":"abort"');
+    expect(result.stderr).toContain('"reason":"SIGINT"');
+  });
+
+  test('SIGINT still defers to another process handler when one is installed', async () => {
+    const result = await runSigintHarness(`
+      const { createProgress } = await import('./src/core/progress.ts');
+      process.once('SIGINT', () => {
+        process.stdout.write('HANDLED\\n');
+        setTimeout(() => process.exit(0), 50);
+      });
+      const progress = createProgress({ mode: 'json' });
+      progress.start('sigint_repro', 1);
+      process.stdout.write('READY\\n');
+      setInterval(() => {}, 1000);
+    `);
+
+    expect(result.exited).toBe(true);
+    expect(result.code).toBe(0);
+    expect(result.signal).toBeNull();
+    expect(result.stdout).toContain('HANDLED');
+    expect(result.stderr).toContain('"event":"abort"');
+    expect(result.stderr).toContain('"reason":"SIGINT"');
+  });
+
   test('startHeartbeat() fires heartbeats and stop() clears', async () => {
     const { stream, read } = sink(false);
     const p = createProgress({ mode: 'json', stream, minIntervalMs: 0, minItems: 1 });