feat: improve logs debugging workflow

README.md

@@ -16,7 +16,7 @@ The project is in early development and considered experimental. Pull requests a
 - Platforms: iOS (simulator + physical device core automation) and Android (emulator + device).
 - Core commands: `open`, `back`, `home`, `app-switcher`, `press`, `long-press`, `focus`, `type`, `fill`, `scroll`, `scrollintoview`, `wait`, `alert`, `screenshot`, `close`, `reinstall`.
 - Inspection commands: `snapshot` (accessibility tree), `diff snapshot` (structural baseline diff), `appstate`, `apps`, `devices`.
-- App logs: `logs path` returns session log metadata; `logs start` / `logs stop` stream app output; `logs doctor` checks readiness; `logs mark` writes timeline markers.
+- App logs: `logs path` returns session log metadata; `logs start` / `logs stop` stream app output; `logs clear` truncates session app logs; `logs clear --restart` resets and restarts stream in one step; `logs doctor` checks readiness; `logs mark` writes timeline markers.
 - Device tooling: `adb` (Android), `simctl`/`devicectl` (iOS via Xcode).
 - Minimal dependencies; TypeScript executed directly on Node 22+ (no build step).
 
@@ -145,7 +145,7 @@ agent-device scrollintoview @e42
 - `press` (alias: `click`), `focus`, `type`, `fill`, `long-press`, `swipe`, `scroll`, `scrollintoview`, `pinch`, `is`
 - `alert`, `wait`, `screenshot`
 - `trace start`, `trace stop`
-- `logs path`, `logs start`, `logs stop`, `logs doctor`, `logs mark` (session app log file for grep; iOS simulator + iOS device + Android)
+- `logs path`, `logs start`, `logs stop`, `logs clear`, `logs clear --restart`, `logs doctor`, `logs mark` (session app log file for grep; iOS simulator + iOS device + Android)
 - `settings wifi|airplane|location on|off`
 - `settings faceid match|nonmatch|enroll|unenroll` (iOS simulator only)
 - `appstate`, `apps`, `devices`, `session list`
@@ -300,9 +300,11 @@ App state:
 
 ## Debug
 
-- **App logs (token-efficient):** With an active session, run `logs path` to get path + state metadata (e.g. `~/.agent-device/sessions/<session>/app.log`). Run `logs start` to stream app output to that file; use `logs stop` to stop. Run `logs doctor` for tool/runtime checks and `logs mark "step"` to insert timeline markers. Grep the file when you need to inspect errors (e.g. `grep -n "Error\|Exception" <path>`) instead of pulling full logs into context. Supported on iOS simulator, iOS physical device, and Android.
+- **App logs (token-efficient):** Logging is off by default in normal flows. Enable it on demand when debugging. With an active session, run `logs path` to get path + state metadata (e.g. `~/.agent-device/sessions/<session>/app.log`). Run `logs start` to stream app output to that file; use `logs stop` to stop. Run `logs clear` to truncate `app.log` (and remove rotated `app.log.N` files) before a new repro window. Run `logs doctor` for tool/runtime checks and `logs mark "step"` to insert timeline markers. Grep the file when you need to inspect errors (e.g. `grep -n "Error\|Exception" <path>`) instead of pulling full logs into context. Supported on iOS simulator, iOS physical device, and Android.
+- Use `logs clear --restart` when you want one command to stop an active stream, clear current logs, and immediately resume streaming.
 - `logs start` appends to `app.log` and rotates to `app.log.1` when the file exceeds 5 MB.
 - Android log streaming automatically rebinds to the app PID after process restarts.
+- Detailed playbook: `skills/agent-device/references/logs-and-debug.md`
 - iOS log capture relies on Unified Logging signals (for example `os_log`); plain stdout/stderr output may be limited depending on app/runtime.
 - Retention knobs: set `AGENT_DEVICE_APP_LOG_MAX_BYTES` and `AGENT_DEVICE_APP_LOG_MAX_FILES` to override rotation limits.
 - Optional write-time redaction patterns: set `AGENT_DEVICE_APP_LOG_REDACT_PATTERNS` to a comma-separated regex list.

skills/agent-device/SKILL.md

@@ -112,16 +112,18 @@ Think of them as validate/invalidate outcomes when describing intent.
 ### Logs (token-efficient debugging)
 
 Use the detailed logs workflow reference:
-`skills/agent-device/references/logs.md`
+`skills/agent-device/references/logs-and-debug.md`
 
 Recommended minimum:
 
 ```bash
 agent-device logs doctor
-agent-device logs start
+agent-device logs clear --restart
 agent-device logs path
 ```
 
+Logging is off by default for normal flows. Turn it on only for debugging windows.
+
 ### App state
 
 ```bash

skills/agent-device/references/logs.md → skills/agent-device/references/logs-and-debug.md

@@ -1,12 +1,12 @@
 # Logs (Token-Efficient Debugging)
 
-App output is written to a session-scoped file so agents can grep it instead of loading full logs into context.
+Logging is off by default in normal flows. Enable it on demand for debugging windows. App output is written to a session-scoped file so agents can grep it instead of loading full logs into context.
 
 ## Quick Flow
 
 ```bash
 agent-device open MyApp --platform ios
-agent-device logs start              # Start streaming app logs to session file
+agent-device logs clear --restart    # Preferred: stop stream, clear logs, and start streaming again
 agent-device logs path               # Print path, e.g. ~/.agent-device/sessions/default/app.log
 agent-device logs doctor             # Check tool/runtime readiness for current session/device
 agent-device logs mark "before tap"  # Insert a timeline marker into app.log
@@ -19,6 +19,8 @@ agent-device logs stop               # Stop streaming (optional; close also stop
 - `logs path`: returns log file path and metadata (`active`, `state`, `backend`, size, timestamps).
 - `logs start`: starts streaming; requires an active app session (`open` first). Supported on iOS simulator, iOS device, and Android.
 - `logs stop`: stops streaming. Session `close` also stops logging.
+- `logs clear`: truncates `app.log` and removes rotated `app.log.N` files. Requires logging to be stopped first.
+- `logs clear --restart`: convenience reset for repro loops (stop stream, clear files, restart stream).
 - `logs doctor`: reports backend/tool checks and readiness notes for troubleshooting.
 - `logs mark`: writes a timestamped marker line to the session log.
 
@@ -49,3 +51,35 @@ tail -50 <path>
 - Use `-n` for line numbers.
 - Use `-E` for extended regex so `|` in the pattern does not need escaping.
 - Prefer targeted patterns (e.g. `Error`, `Exception`, or app-specific tags) over reading the full file.
+
+## Crash Triage Fast Path
+
+Always start from the session app log, then branch by platform.
+
+```bash
+agent-device logs path
+grep -n -E "SIGABRT|SIGSEGV|EXC_|fatal|exception|terminated|killed|jetsam|memorystatus|FATAL EXCEPTION|Abort message" <path>
+nl -ba <path> | sed -n '<start>,<end>p'
+```
+
+### iOS
+
+```bash
+# If log shows ReportCrash / SIGABRT / EXC_*, inspect simulator DiagnosticReports:
+ls -lt ~/Library/Logs/DiagnosticReports | grep -E "<AppName>|<BundleId>" | head
+```
+
+- `SIGABRT`: app/runtime abort; inspect `.ips` triggered thread and top frames.
+- `SIGKILL` + jetsam/memorystatus markers: memory-pressure kill.
+- `EXC_BAD_ACCESS`/`SIGSEGV`: native memory access issue.
+
+### Android
+
+```bash
+# Capture fatal crash lines around app process death:
+adb -s <serial> logcat -d | grep -n -E "FATAL EXCEPTION|Process: <package>|Abort message|signal [0-9]+ \\(SIG"
+```
+
+- `FATAL EXCEPTION` with Java stack: uncaught Java/Kotlin exception.
+- `signal 6 (SIGABRT)` or `signal 11 (SIGSEGV)` with tombstone refs: native crash path (NDK/JNI/runtime).
+- `Low memory killer` / `Killing <pid>` entries: OS memory-pressure/process reclaim.

src/__tests__/cli-logs.test.ts

@@ -0,0 +1,84 @@
+import test from 'node:test';
+import assert from 'node:assert/strict';
+import { runCli } from '../cli.ts';
+import type { DaemonRequest, DaemonResponse } from '../daemon-client.ts';
+
+class ExitSignal extends Error {
+  public readonly code: number;
+
+  constructor(code: number) {
+    super(`EXIT_${code}`);
+    this.code = code;
+  }
+}
+
+type RunResult = {
+  code: number | null;
+  stdout: string;
+  stderr: string;
+  calls: Omit<DaemonRequest, 'token'>[];
+};
+
+async function runCliCapture(
+  argv: string[],
+  responder: (req: Omit<DaemonRequest, 'token'>) => Promise<DaemonResponse>,
+): Promise<RunResult> {
+  let stdout = '';
+  let stderr = '';
+  let code: number | null = null;
+  const calls: Array<Omit<DaemonRequest, 'token'>> = [];
+
+  const originalExit = process.exit;
+  const originalStdoutWrite = process.stdout.write.bind(process.stdout);
+  const originalStderrWrite = process.stderr.write.bind(process.stderr);
+
+  (process as any).exit = ((nextCode?: number) => {
+    throw new ExitSignal(nextCode ?? 0);
+  }) as typeof process.exit;
+  (process.stdout as any).write = ((chunk: unknown) => {
+    stdout += String(chunk);
+    return true;
+  }) as typeof process.stdout.write;
+  (process.stderr as any).write = ((chunk: unknown) => {
+    stderr += String(chunk);
+    return true;
+  }) as typeof process.stderr.write;
+
+  const sendToDaemon = async (req: Omit<DaemonRequest, 'token'>): Promise<DaemonResponse> => {
+    calls.push(req);
+    return await responder(req);
+  };
+
+  try {
+    await runCli(argv, { sendToDaemon });
+  } catch (error) {
+    if (error instanceof ExitSignal) code = error.code;
+    else throw error;
+  } finally {
+    process.exit = originalExit;
+    process.stdout.write = originalStdoutWrite;
+    process.stderr.write = originalStderrWrite;
+  }
+
+  return { code, stdout, stderr, calls };
+}
+
+test('logs clear prints action metadata and forwards --restart flag', async () => {
+  const result = await runCliCapture(['logs', 'clear', '--restart'], async () => ({
+    ok: true,
+    data: {
+      path: '/tmp/app.log',
+      cleared: true,
+      restarted: true,
+      removedRotatedFiles: 2,
+    },
+  }));
+
+  assert.equal(result.code, null);
+  assert.equal(result.calls.length, 1);
+  assert.equal(result.calls[0]?.flags?.restart, true);
+  assert.match(result.stdout, /\/tmp\/app\.log/);
+  assert.match(result.stderr, /cleared=true/);
+  assert.match(result.stderr, /restarted=true/);
+  assert.match(result.stderr, /removedRotatedFiles=2/);
+});

src/cli.ts

@@ -249,6 +249,13 @@ export async function runCli(argv: string[], deps: CliDeps = DEFAULT_CLI_DEPS):
           const state = typeof data?.state === 'string' ? data.state : undefined;
           const backend = typeof data?.backend === 'string' ? data.backend : undefined;
           const sizeBytes = typeof data?.sizeBytes === 'number' ? data.sizeBytes : undefined;
+          const started = data?.started === true;
+          const stopped = data?.stopped === true;
+          const marked = data?.marked === true;
+          const cleared = data?.cleared === true;
+          const restarted = data?.restarted === true;
+          const removedRotatedFiles =
+            typeof data?.removedRotatedFiles === 'number' ? data.removedRotatedFiles : undefined;
           if (!flags.json && (active !== undefined || state || backend || sizeBytes !== undefined)) {
             const meta = [
               active !== undefined ? `active=${active}` : '',
@@ -258,6 +265,17 @@ export async function runCli(argv: string[], deps: CliDeps = DEFAULT_CLI_DEPS):
             ].filter(Boolean).join(' ');
             if (meta) process.stderr.write(`${meta}\n`);
           }
+          if (!flags.json && (started || stopped || marked || cleared || restarted || removedRotatedFiles !== undefined)) {
+            const actionMeta = [
+              started ? 'started=true' : '',
+              stopped ? 'stopped=true' : '',
+              marked ? 'marked=true' : '',
+              cleared ? 'cleared=true' : '',
+              restarted ? 'restarted=true' : '',
+              removedRotatedFiles !== undefined ? `removedRotatedFiles=${removedRotatedFiles}` : '',
+            ].filter(Boolean).join(' ');
+            if (actionMeta) process.stderr.write(`${actionMeta}\n`);
+          }
           if (data?.hint && !flags.json) {
             process.stderr.write(`${data.hint}\n`);
           }

src/daemon/__tests__/app-log.test.ts

@@ -9,6 +9,7 @@ import {
   assertAndroidPackageArgSafe,
   buildIosDeviceLogStreamArgs,
   buildIosLogPredicate,
+  clearAppLogFiles,
   cleanupStaleAppLogProcesses,
   getAppLogPathMetadata,
   runAppLogDoctor,
@@ -111,6 +112,23 @@ test('appendAppLogMarker writes marker lines and metadata reflects file', () =>
   assert.ok(metadata.sizeBytes > 0);
 });
 
+test('clearAppLogFiles truncates current log and removes rotated log files', () => {
+  const root = fs.mkdtempSync(path.join(os.tmpdir(), 'agent-device-app-log-clear-'));
+  const outPath = path.join(root, 'app.log');
+  fs.writeFileSync(outPath, 'line1\nline2\n');
+  fs.writeFileSync(`${outPath}.1`, 'older');
+  fs.writeFileSync(`${outPath}.2`, 'oldest');
+
+  const result = clearAppLogFiles(outPath);
+
+  assert.equal(result.path, outPath);
+  assert.equal(result.cleared, true);
+  assert.equal(result.removedRotatedFiles, 2);
+  assert.equal(fs.readFileSync(outPath, 'utf8'), '');
+  assert.equal(fs.existsSync(`${outPath}.1`), false);
+  assert.equal(fs.existsSync(`${outPath}.2`), false);
+});
+
 test('runAppLogDoctor returns note when app bundle is missing', async () => {
   const result = await runAppLogDoctor({
     platform: 'android',

src/daemon/app-log.ts

@@ -496,4 +496,28 @@ export function appendAppLogMarker(outPath: string, marker: string): void {
   fs.appendFileSync(outPath, line, 'utf8');
 }
 
+export function clearAppLogFiles(outPath: string): { path: string; cleared: boolean; removedRotatedFiles: number } {
+  const dir = path.dirname(outPath);
+  const base = path.basename(outPath);
+  if (!fs.existsSync(dir)) fs.mkdirSync(dir, { recursive: true });
+  if (fs.existsSync(outPath)) {
+    fs.truncateSync(outPath, 0);
+  } else {
+    fs.writeFileSync(outPath, '', 'utf8');
+  }
+  let removedRotatedFiles = 0;
+  for (const entry of fs.readdirSync(dir)) {
+    if (!entry.startsWith(`${base}.`)) continue;
+    const suffix = entry.slice(base.length + 1);
+    if (!/^\d+$/.test(suffix)) continue;
+    try {
+      fs.unlinkSync(path.join(dir, entry));
+      removedRotatedFiles += 1;
+    } catch {
+      // best-effort cleanup
+    }
+  }
+  return { path: outPath, cleared: true, removedRotatedFiles };
+}
+
 export const APP_LOG_PID_FILENAME = APP_LOG_PID_FILE;