chore(qw): cleanup post-review (préfixes BUS, événements monitor, import io)

- safety_checks_provider : tous les logger.warning d'échec LLM préfixés
  [BUS] lea:safety_checks_llm_failed avec une raison spécifique
  (exception, http_status, timeout, network, json_decode).
- monitor_router : émission [BUS] lea:monitor_invalid_index si l'index
  explicite passé dans l'action est hors limites de monitors_geometry,
  et [BUS] lea:monitor_unavailable si focus actif demandé mais introuvable.
  Ces deux events permettent au bus de tracer chaque fallback de la cascade
  de routage QW1.
- safety_checks_provider : import io supprimé (inutilisé).

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

agent_v0/server_v1/monitor_router.py

@@ -9,9 +9,12 @@ Stratégie en cascade :
 Émet sur le bus lea:* l'event monitor_routed avec la source de la décision.
 """
 
+import logging
 from dataclasses import dataclass
 from typing import Any, Dict, List, Optional
 
+logger = logging.getLogger(__name__)
+
 
 @dataclass
 class MonitorTarget:
@@ -76,6 +79,10 @@ def resolve_target_monitor(
         if m is not None:
             return _to_target(m, source="action")
         # Index invalide → on tombe sur le fallback focus
+        logger.warning(
+            "[BUS] lea:monitor_invalid_index requested=%d available_idx=%s",
+            int(explicit_idx), [g.get("idx") for g in geometry],
+        )
 
     # 2. Fallback focus actif
     focused_idx = session_state.get("last_focused_monitor")
@@ -83,6 +90,10 @@ def resolve_target_monitor(
         m = _find_monitor(geometry, int(focused_idx))
         if m is not None:
             return _to_target(m, source="focus")
+        logger.warning(
+            "[BUS] lea:monitor_unavailable focused_idx=%d available_idx=%s",
+            int(focused_idx), [g.get("idx") for g in geometry],
+        )
 
     # 3. Fallback composite (backward compat — comportement actuel mss.monitors[0])
     return _COMPOSITE_FALLBACK

agent_v0/server_v1/safety_checks_provider.py

@@ -11,7 +11,6 @@ le replay continue avec uniquement les déclaratifs (fallback safe).
 """
 
 import base64
-import io
 import json
 import logging
 import os
@@ -77,7 +76,7 @@ def build_pause_payload(
                 existing_labels=[c["label"] for c in checks],
             )
         except Exception as e:
-            logger.warning("safety_checks LLM exception (%s) — fallback safe", e)
+            logger.warning("[BUS] lea:safety_checks_llm_failed reason=exception detail=%s", e)
             additional = []
 
         for a in additional:
@@ -159,21 +158,21 @@ Réponds UNIQUEMENT en JSON :
             timeout=timeout_s,
         )
         if response.status_code != 200:
-            logger.warning("safety_checks LLM HTTP %s", response.status_code)
+            logger.warning("[BUS] lea:safety_checks_llm_failed reason=http_status detail=%s", response.status_code)
             return []
         text = response.json().get("response", "").strip()
     except requests.Timeout:
-        logger.warning("safety_checks LLM timeout (%ss)", timeout_s)
+        logger.warning("[BUS] lea:safety_checks_llm_failed reason=timeout detail=%ss", timeout_s)
         return []
     except Exception as e:
-        logger.warning("safety_checks LLM erreur réseau: %s", e)
+        logger.warning("[BUS] lea:safety_checks_llm_failed reason=network detail=%s", e)
         return []
 
     # format=json garantit normalement du JSON valide
     try:
         parsed = json.loads(text)
     except json.JSONDecodeError as e:
-        logger.warning("safety_checks LLM JSON invalide (%s) — fallback safe", e)
+        logger.warning("[BUS] lea:safety_checks_llm_failed reason=json_decode detail=%s", e)
         return []
 
     additional = parsed.get("additional_checks") or []