fix(browse): Chromium-crash exit is daemon-only — embedded launches never kill their host

handleChromiumDisconnect unconditionally process.exit()ed. Correct for
the standalone daemon (its supervisor/user must notice); suicidal when
a TEST launches BrowserManager in-process: a mid-suite Chromium death
exited the whole bun shard with no terminal summary — the exact
truncation class the strict runner flags (observed live: CI shard 1 on
eb233299 died at cache-concurrent-refresh right after a daemon-spawning
gate test; with this fix the same pairing runs to completion and
REPORTS instead of dying).

The standalone entrypoint opts in via markDaemonProcess() under
server.ts's import.meta.main gate — the same embedder contract its
signal handlers already use (gbrowser phoenix keeps its own handlers).
Embedded contexts now get the disconnect log line and continue.

Co-Authored-By: Claude Fable 5 <noreply@anthropic.com>

browse/src/browser-manager.ts

@@ -186,12 +186,32 @@ export async function resolveDisconnectCause(browser: Browser | null): Promise<'
 }
 
 /**
- * Headless `launch()` disconnect handler. Exits 0 on clean user-quit, 1 on
- * crash. Inlined into the launch() body via a one-line dispatch so
+ * Exit-on-disconnect is DAEMON-ONLY semantics. The standalone server
+ * entrypoint opts in via markDaemonProcess() (under its import.meta.main
+ * gate, same contract as its signal handlers); embedders — gbrowser
+ * phoenix, and every test that launches a BrowserManager in-process —
+ * must never have a Chromium crash process.exit() their HOST. Observed
+ * live before this flag: a test-launched browser died mid-suite and the
+ * exit(1) killed the whole bun shard with no terminal summary (the
+ * truncation class the strict runner exists to catch).
+ */
+let daemonProcess = false;
+export function markDaemonProcess(): void {
+  daemonProcess = true;
+}
+
+/**
+ * Headless `launch()` disconnect handler. In the standalone daemon: exits 0
+ * on clean user-quit, 1 on crash. Embedded contexts get the log line only.
+ * Inlined into the launch() body via a one-line dispatch so
  * browser-manager's flow stays grep-friendly.
  */
 export async function handleChromiumDisconnect(browser: Browser | null): Promise<void> {
   const cause = await resolveDisconnectCause(browser);
+  if (!daemonProcess) {
+    console.error(`[browse] Chromium disconnected (${cause}) in an embedded context — host process continues.`);
+    return;
+  }
   if (cause === 'clean') {
     console.error('[browse] Chromium closed cleanly (user-initiated quit). Server exiting (0).');
     process.exit(0);

browse/src/server.ts

@@ -13,7 +13,7 @@
  *   Port:       random 10000-60000 (or BROWSE_PORT env for debug override)
  */
 
-import { BrowserManager } from './browser-manager';
+import { BrowserManager, markDaemonProcess } from './browser-manager';
 import { handleReadCommand, hasOutArg } from './read-commands';
 import { handleWriteCommand } from './write-commands';
 import { handleMetaCommand } from './meta-commands';
@@ -1394,6 +1394,10 @@ async function handleCommand(body: any, tokenInfo?: TokenInfo | null): Promise<R
 // server.ts as a submodule can register their own signal handlers without
 // fighting with gstack's. CLI path is unchanged.
 if (import.meta.main) {
+  // Standalone daemon: a Chromium crash must exit THIS process (its
+  // supervisor/user notices); embedders and in-process test launches must
+  // never be exited by browser-manager's disconnect handler.
+  markDaemonProcess();
   // SIGINT (Ctrl+C): user intentionally stopping → shutdown.
   process.on('SIGINT', () => activeShutdown?.());
   // SIGHUP (terminal hangup): with handleSIGHUP:false at the three launch