snapshot: WIP 5j replay reliability (B1 watchdog + dialog handlers + grounding drift)

Snapshot avant correction du blocage relance Léa (3 incidents 24h: SSH refusé,
polls morts ×2). Point de rollback stable.

Contenu:
- agent_v1/core/executor.py: 5 patchs dialog handling (saveas drift, close_tab
  hotkey fallback, confirm_save Unicode apostrophe, foreground dialog
  recontextualization, runtime_dialog in-loop) + helpers normalize_window_hint,
  requires_post_verify_window_transition
- agent_v1/core/grounding.py: garde drift template fix (fallback_x/y plumbed)
- server_v1/replay_watchdog.py (NEW): orphan watchdog B1, scan 10s timeout 30s
- server_v1/api_stream.py: dispatched_action plumbing, watchdog lifespan,
  metrics endpoint
- server_v1/replay_engine.py: _schedule_retry préserve original_action +
  dispatched_action
- stream_processor.py: gardes _infer_tab_switch_target (no false switch_tab
  on save_as dialog open) + _attach_expected_window_before
- tests/integration: test_replay_watchdog.py (8 cas), test_stream_processor.py
- tests/unit: test_executor_verify_window_guard.py (start_button, close_tab,
  runtime_dialog, post_verify, transition fallbacks)

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

agent_v0/agent_v1/ui/capture_server.py

@@ -158,14 +158,25 @@ class CaptureHandler(BaseHTTPRequestHandler):
         """Capture l'ecran principal et le renvoie en base64 JPEG."""
         t0 = time.perf_counter()
         try:
-            import mss
-            from PIL import Image
+            from ..vision.capturer import (
+                capture_foreground_window_image,
+                capture_screen_image,
+            )
 
-            with mss.mss() as sct:
-                monitor = sct.monitors[1]  # ecran principal
-                raw = sct.grab(monitor)
-
-            img = Image.frombytes("RGB", raw.size, raw.bgra, "raw", "BGRX")
+            _monitor, img, meta = capture_screen_image()
+            if img is None:
+                img, win_meta = capture_foreground_window_image()
+                meta.update(win_meta)
+            if img is None:
+                elapsed_ms = (time.perf_counter() - t0) * 1000
+                logger.error("Erreur capture : aucun backend exploitable (%s)", meta)
+                self._send_json(503, {
+                    "error": "capture_unavailable",
+                    "source": meta.get("backend", "unknown"),
+                    "capture_ms": round(elapsed_ms),
+                    "diagnostics": meta,
+                })
+                return
 
             # Floutage des données sensibles (conformité AI Act)
             if BLUR_SENSITIVE:
@@ -180,15 +191,22 @@ class CaptureHandler(BaseHTTPRequestHandler):
             img_b64 = base64.b64encode(buf.getvalue()).decode()
 
             elapsed_ms = (time.perf_counter() - t0) * 1000
-            logger.info(f"Capture {img.width}x{img.height} en {elapsed_ms:.0f}ms")
+            logger.info(
+                "Capture %sx%s via %s en %.0fms",
+                img.width,
+                img.height,
+                meta.get("backend", "unknown"),
+                elapsed_ms,
+            )
 
             self._send_json(200, {
                 "image": img_b64,
                 "width": img.width,
                 "height": img.height,
                 "format": "jpeg",
-                "source": "windows_live",
+                "source": meta.get("backend", "windows_live"),
                 "capture_ms": round(elapsed_ms),
+                "diagnostics": meta,
             })
 
         except Exception as e: