feat(security): wire logAttempt to gstack-telemetry-log (fire-and-forget)

Every local attempt.jsonl write now also triggers a subprocess call to
gstack-telemetry-log with the attack_attempt event type. The binary handles
tier gating internally (community → Supabase upload, anonymous → local
JSONL only, off → no-op), so security.ts doesn't need to re-check.

Binary resolution follows the skill preamble pattern — never relies on PATH,
which breaks in compiled-binary contexts:

  1. ~/.claude/skills/gstack/bin/gstack-telemetry-log  (global install)
  2. .claude/skills/gstack/bin/gstack-telemetry-log    (symlinked dev)
  3. bin/gstack-telemetry-log                          (in-repo dev)

Fire-and-forget:
  * spawn with stdio: 'ignore', detached: true, unref()
  * .on('error') swallows failures
  * Missing binary is non-fatal — local attempts.jsonl still gives audit trail

Never throws. Never blocks. Existing 37 security tests pass unchanged.

Co-Authored-By: Claude Opus 4.7 (1M context) <noreply@anthropic.com>

browse/src/security.ts

@@ -20,6 +20,7 @@
  */
 
 import { randomBytes, createHash } from 'crypto';
+import { spawn } from 'child_process';
 import * as fs from 'fs';
 import * as path from 'path';
 import * as os from 'os';
@@ -258,10 +259,74 @@ function rotateIfNeeded(): void {
 }
 
 /**
- * Append an attempt to the local log. Never throws — logging failure should
- * not break the sidebar. Returns true if the write succeeded.
+ * Try to locate the gstack-telemetry-log binary. Resolution order matches
+ * the existing skill preamble pattern (never relies on PATH — packaged
+ * binary layouts can break that).
+ *
+ * Order:
+ *  1. ~/.claude/skills/gstack/bin/gstack-telemetry-log  (global install)
+ *  2. .claude/skills/gstack/bin/gstack-telemetry-log    (symlinked dev)
+ *  3. bin/gstack-telemetry-log                          (in-repo dev)
+ */
+function findTelemetryBinary(): string | null {
+  const candidates = [
+    path.join(os.homedir(), '.claude', 'skills', 'gstack', 'bin', 'gstack-telemetry-log'),
+    path.resolve(process.cwd(), '.claude', 'skills', 'gstack', 'bin', 'gstack-telemetry-log'),
+    path.resolve(process.cwd(), 'bin', 'gstack-telemetry-log'),
+  ];
+  for (const c of candidates) {
+    try {
+      fs.accessSync(c, fs.constants.X_OK);
+      return c;
+    } catch {
+      // try next
+    }
+  }
+  return null;
+}
+
+/**
+ * Fire-and-forget subprocess invocation of gstack-telemetry-log with the
+ * attack_attempt event type. The binary handles tier gating internally
+ * (community → upload, anonymous → local only, off → no-op), so we don't
+ * need to re-check here.
+ *
+ * Never throws. Never blocks. If the binary isn't found or spawn fails, the
+ * local attempts.jsonl write from logAttempt() still gives us the audit trail.
+ */
+function reportAttemptTelemetry(record: AttemptRecord): void {
+  const bin = findTelemetryBinary();
+  if (!bin) return;
+  try {
+    const child = spawn(bin, [
+      '--event-type', 'attack_attempt',
+      '--url-domain', record.urlDomain || '',
+      '--payload-hash', record.payloadHash,
+      '--confidence', String(record.confidence),
+      '--layer', record.layer,
+      '--verdict', record.verdict,
+    ], {
+      stdio: 'ignore',
+      detached: true,
+    });
+    // unref so this subprocess doesn't hold the event loop open
+    child.unref();
+    child.on('error', () => { /* swallow — telemetry must never break sidebar */ });
+  } catch {
+    // Spawn failure is non-fatal.
+  }
+}
+
+/**
+ * Append an attempt to the local log AND fire telemetry via
+ * gstack-telemetry-log (which respects the user's telemetry tier setting).
+ * Never throws — logging failure should not break the sidebar.
+ * Returns true if the local write succeeded.
  */
 export function logAttempt(record: AttemptRecord): boolean {
+  // Fire telemetry first, async — even if local write fails, we still want
+  // the event reported (it goes to a different directory anyway).
+  reportAttemptTelemetry(record);
   try {
     fs.mkdirSync(SECURITY_DIR, { recursive: true, mode: 0o700 });
     rotateIfNeeded();