fix watcher failure detection for host reporter json

Handle dict-shaped reporter events when deriving watcher host failures.

- parse reporter JSON events with type/message/severity fields
- preserve existing support for list-shaped event records
- record the false-PASS failure mode in ATVM automation run learnings

atvm/docs/automation/run-learnings.md

@@ -18,6 +18,15 @@ This file stores run-specific examples only when a run produced a new learning r
   - Write the template phase output to `/tmp/<build>.launch.log` so template activity is preserved separately from the live runner log.
   - If the template step fails, stop immediately and do not start the watcher or the runner.
 
+## Run Learning: 2026-04-29 (Watcher host-artifact parser must handle dict-shaped reporter events)
+- Observed failure mode:
+  - A non-categorized ATVM compute-migration run failed in the host reporter artifacts, but the watcher posted `PASS`.
+  - The watcher fell back to the per-host JSON artifact after `check-xml-files.ts`, but `extract_failure_from_reporter_events()` only recognized the older list-shaped event format.
+  - Current reporter JSON stores events as dicts with fields such as `type`, `message`, and `severity`, so the parser missed `severity: error` and incorrectly returned `0 failures`.
+- Action for future runs:
+  - Treat both list-shaped and dict-shaped reporter event records as valid inputs when extracting failure details from host JSON artifacts.
+  - Continue treating host reporter artifacts as authoritative fallback evidence when final XML only contains `check-xml-files.ts`.
+
 ## Run Learning: 2026-04-24 (Categorized watcher false-PASS guardrail)
 - Observed failure mode:
   - A categorized compute-migration run was incorrectly reported as `PASS` for `atvm121-ubuntu24.04` even though the actual Ubuntu grouped sub-run failed.

atvm/watcher-service/atvm_run_watcher.py

@@ -524,11 +524,16 @@ def extract_failure_from_reporter_events(testcase_name: str, testcase_events: ob
     if not isinstance(testcase_events, list):
         return None
     for event in testcase_events:
-        if not isinstance(event, list) or len(event) < 3:
+        if isinstance(event, dict):
+            event_type = str(event.get("type", "")).lower()
+            message_value = str(event.get("message", ""))
+            status_value = str(event.get("severity", "")).lower()
+        elif isinstance(event, list) and len(event) >= 3:
+            event_type = str(event[0]).lower()
+            message_value = str(event[1]) if len(event) > 1 else ""
+            status_value = str(event[2]).lower()
+        else:
             continue
-        event_type = str(event[0]).lower()
-        message_value = str(event[1]) if len(event) > 1 else ""
-        status_value = str(event[2]).lower()
         if event_type in {"cy:command", "cy:task"} and status_value in {"failed", "fail", "error"}:
             return compact_failure_detail(f"{concise_testcase_name(testcase_name)} - {message_value}")
     return None