[lauridskern]

Closes #48.

Why

Hosts can update or uninstall Mobile Dev while its server is still running. The update deletes the version folder that the old server reads serve-emu and Baguette from, so the next Android stream or simulator open fails.

The Sentry users match up:

• 9 of the 15 users in MOBILE-DEV-SERVER-68 (serve-emu) also appear in MOBILE-DEV-SERVER-7B (failed updates).
• The Baguette issue, MOBILE-DEV-SERVER-7C (14 users), overlaps with both.
• Several users lost both runtimes in the same second, minutes after a failed update, on the same release.

The packages themselves were complete. Users saw a developer message ("Run npm run vendor:serve-emu…"), and the panel retried on every reconnect.

What changes

• Install integrity. packages/core/src/install-integrity.ts records the inode and modification time of the server's bundle file when it loads. Later it can tell whether those files are intact, removed or replaced.
• A message the user can act on. A missing serve-emu or Baguette throws MissingRuntimeError:
  • When the server's files were removed or replaced, it says Mobile Dev was updated or removed while running, and asks the user to restart the app running it.
  • When the server's files are intact but the runtime was never there, it asks for a reinstall.
• No retry storms. The panel now gets retryable: false for missing runtimes, as it already did for unavailable devices. The three duplicated checks became one retryableFailure().
• Telemetry. A client event processor tags every error event from a server whose files are gone with install_integrity, however the event was captured. Missing-runtime errors also carry bundled_runtime, with install_integrity: incomplete when the install never had the runtime.
• Store migration. installLatest no longer exists. Its replacement, migrateToStore, reported the same single generic error. It now tags plugin_update_step and plugin_update_failure, and the user-facing messages are unchanged.
• docs/telemetry.md documents the new tags.

Not in this PR

• Surviving the deletion. The old server could keep working if it ran from a stable copy of dist/, the way the Android CPU collector keeps its binaries in memory. But dist/ is about 131 MB, and this would change how every host launches the server, so it belongs in its own PR.
• Other bundled helpers. iOS logs, the iOS mirror, FPS and agent-device still fail with their own errors after a deletion. Their events now carry install_integrity, so Sentry can show how often this happens.
• Expected outcome. Once the field data confirms the cause, removed and replaced could count as expected outcomes, with only incomplete reported as an issue.

Testing

• npm test: 877 of 880 passed, 1 skipped. Two TraceSift tests failed while npm run build ran at the same time; tracesift-client.test.ts passes on its own (14/14).
• npm run typecheck:telemetry passes. A full tsc reports the same errors as main.
• New tests:
  • install-integrity.test.ts bundles the module as a real server.mjs, then deletes or replaces that file.
  • android.test.ts calls mobile_android_stream_session through the real ServeEmu start path and checks the message and retryable: false.
  • Telemetry and migration tests check the Sentry tags.
• End to end with npm run build, running dist/server.mjs from a copy:
  • Deleting the copy while the server ran made mobile_open_simulator say: "Mobile Dev was updated or removed while it was running and cannot find its simulator backend. Restart the app running Mobile Dev to load the installed version."
  • Starting a copy without baguette/ made it say: "This Mobile Dev installation is missing its simulator backend. Reinstall Mobile Dev, then restart the app running it."

[lauridskern]

@codex review this