Require watcher startup before ATVM runner launch

- update the ATVM automation guide to make watcher-first launch order explicit whenever the watcher is approved
- update the ATVM AGENTS rules so the runner is never started before the watcher for watcher-backed runs
- add a 2026-03-27 run learning documenting that the watcher helper can delete the live runner log if the runner starts first

atvm/AGENTS.md

@@ -62,6 +62,8 @@ This file defines how to operate and maintain the ATVM workspace in `/home/aw/co
 - For ATVM run approvals, treat `approve` as run-without-watcher and `approve with watcher` as run-with-watcher.
 - After `cmc-templates.py`, always verify that the generated spec files and the config `specPattern` still include every requested VM before starting `run-sorry-cypress.py`.
 - If any requested VM is missing after template generation, stop and report the mismatch instead of launching the runner.
+- When the watcher is requested, start the watcher before `run-sorry-cypress.py`.
+- Do not start the runner before the watcher, because the watcher helper clears stale `/tmp/<build-name>.log` and can delete the fresh live runner log if the runner starts first.
 - For host-level test detail and failed-test investigation, use `/root/cdc-e2e-cyp-12.17.4/cypress/cmcReporter`, especially `logs/`, `xml/`, and `mochawesome/`.
 - If the operator asks for ATVM run status without mentioning Mattermost, respond locally only and do not post externally.
 - If the operator asks to send ATVM run status to Mattermost, use `MATTERMOST_ATVM_WEBHOOK` and `MATTERMOST_ATVM_CHANNEL` from `/home/aw/code/cds/.env.credentials.local` by default and send the final status only after the run has fully completed, whether the run passed or failed.