feat(frontend): update sessions page for enhanced health monitoring

- Add new status badges: starting, probing, unhealthy
- Show tunnel error only when tunnel_status is unreachable
- Show app error badge with status code for error_response
- Add collapsible probe output section for diagnostics
- Update health polling to check all active instances
- Only show Recreate Tunnel button for unreachable tunnels

apps/api/src/services/docker.py

@@ -244,24 +244,94 @@ def connect_container_to_network(container_name: str, network_name: str = "backe
     return result.returncode == 0
 
 
-def get_container_status(container_id: str) -> str:
+def get_container_status(container_id: str) -> dict[str, Any]:
     """Get the status of a Docker container.
 
     Args:
         container_id: Docker container ID
 
     Returns:
-        Container status string (running, exited, etc.)
+        Dict with 'status' (running, exited, restarting, not_found), 
+        'exit_code' (int or None), and 'health' (health status or None)
     """
     result = subprocess.run(
-        ["docker", "inspect", "-f", "{{.State.Status}}", container_id],
+        [
+            "docker", "inspect", "-f",
+            "{{.State.Status}}|{{.State.ExitCode}}|{{if .State.Health}}{{.State.Health.Status}}{{else}}none{{end}}",
+            container_id,
+        ],
         capture_output=True,
         text=True,
     )
 
-    if result.returncode == 0:
-        return result.stdout.strip()
-    return "unknown"
+    if result.returncode != 0:
+        return {"status": "not_found", "exit_code": None, "health": None}
+    
+    parts = result.stdout.strip().split("|")
+    status = parts[0] if parts else "unknown"
+    exit_code = int(parts[1]) if len(parts) > 1 and parts[1].isdigit() else None
+    health = parts[2] if len(parts) > 2 and parts[2] != "none" else None
+    
+    return {"status": status, "exit_code": exit_code, "health": health}
+
+
+def wait_for_container_running(
+    container_id: str, timeout: int = 30, interval: float = 2.0
+) -> dict[str, Any]:
+    """Wait for a container to reach the running state.
+
+    Polls docker inspect until the container status is "running" or timeout.
+
+    Args:
+        container_id: Docker container ID
+        timeout: Maximum seconds to wait
+        interval: Seconds between polls
+
+    Returns:
+        Dict with 'success' (bool), 'status' (str), 'exit_code' (int or None),
+        and 'waited_seconds' (float)
+    """
+    import time
+
+    start_time = time.time()
+    
+    while time.time() - start_time < timeout:
+        info = get_container_status(container_id)
+        
+        if info["status"] == "running":
+            return {
+                "success": True,
+                "status": "running",
+                "exit_code": None,
+                "waited_seconds": time.time() - start_time,
+            }
+        
+        if info["status"] == "exited":
+            return {
+                "success": False,
+                "status": "exited",
+                "exit_code": info["exit_code"],
+                "waited_seconds": time.time() - start_time,
+            }
+        
+        if info["status"] == "not_found":
+            return {
+                "success": False,
+                "status": "not_found",
+                "exit_code": None,
+                "waited_seconds": time.time() - start_time,
+            }
+        
+        time.sleep(interval)
+    
+    # Timeout reached
+    info = get_container_status(container_id)
+    return {
+        "success": False,
+        "status": info["status"],
+        "exit_code": info["exit_code"],
+        "waited_seconds": time.time() - start_time,
+    }
 
 
 def get_container_logs(container_id: str, tail: int = 100) -> str:
@@ -424,14 +494,15 @@ def recreate_tunnel(
 
 
 def check_tunnel_health(url: str, timeout: int = 10) -> dict[str, Any]:
-    """Check if a tunnel URL is healthy.
+    """Check if a tunnel URL is healthy with smart error classification.
 
     Args:
         url: The tunnel URL to check
         timeout: Request timeout in seconds
 
     Returns:
-        Dict with 'healthy' (bool) and 'status_code' (int or None)
+        Dict with 'tunnel_status' (healthy, unreachable, error_response, not_applicable),
+        'status_code' (int or None), 'healthy' (bool), and 'error' (str or None)
     """
     import subprocess
 
@@ -444,13 +515,49 @@ def check_tunnel_health(url: str, timeout: int = 10) -> dict[str, Any]:
             timeout=timeout + 5,
         )
         status_code = int(result.stdout.strip())
+        
+        if 200 <= status_code < 400:
+            return {
+                "tunnel_status": "healthy",
+                "status_code": status_code,
+                "healthy": True,
+                "error": None,
+            }
+        elif status_code in (502, 503, 504):
+            # Application error, not tunnel error
+            return {
+                "tunnel_status": "error_response",
+                "status_code": status_code,
+                "healthy": False,
+                "error": f"Application returned HTTP {status_code}",
+            }
+        else:
+            return {
+                "tunnel_status": "error_response",
+                "status_code": status_code,
+                "healthy": False,
+                "error": f"HTTP {status_code}",
+            }
+    except subprocess.TimeoutExpired:
         return {
-            "healthy": 200 <= status_code < 400,
-            "status_code": status_code,
-        }
-    except (ValueError, subprocess.TimeoutExpired, Exception) as e:
-        return {
-            "healthy": False,
+            "tunnel_status": "unreachable",
             "status_code": None,
+            "healthy": False,
+            "error": "Tunnel request timed out",
+        }
+    except (ValueError, Exception) as e:
+        error_str = str(e).lower()
+        # Classify connection errors
+        if any(err in error_str for err in ["connection refused", "econnrefused", "could not resolve", "nodename"]):
+            return {
+                "tunnel_status": "unreachable",
+                "status_code": None,
+                "healthy": False,
+                "error": f"Tunnel unreachable: {e}",
+            }
+        return {
+            "tunnel_status": "unreachable",
+            "status_code": None,
+            "healthy": False,
             "error": str(e),
         }