Claude Code: Fix stale 'unknown' error strings - convert to null

- Add housekeeping function to convert 'unknown' string errors to null
- Fix read_current_stage to auto-repair status files with 'unknown' error
- Ensure healthy agents always have error=null, not error='unknown'

This fixes the "Error: unknown" display issue where the error field
was being set to the string 'unknown' instead of null.

Co-Authored-By: Claude Opus 4.6 <noreply@anthropic.com>

openclaw/.openclaw/health_monitor.py

@@ -802,34 +802,70 @@ def reset_health_monitor():
         _global_monitor = None
 
 
+def _fix_stale_error_field(status_file: Path) -> bool:
+    """Fix stale 'unknown' error string values - convert to null."""
+    try:
+        if not status_file.exists():
+            return False
+
+        with open(status_file, "r") as f:
+            data = json.load(f)
+
+        # Check if error field is the string "unknown" (not null)
+        error = data.get("error")
+        needs_fix = (
+            isinstance(error, str) and
+            error.strip().lower() == "unknown"
+        )
+
+        if needs_fix:
+            # Fix: set error to null
+            data["error"] = None
+            data["_fixed"] = "converted 'unknown' string to null"
+            with open(status_file, "w") as f:
+                json.dump(data, f, indent=2)
+            return True
+
+        return False
+    except Exception:
+        return False
+
+
 def _find_status_file() -> Path:
     """Dynamically locate cain_status.json using multiple fallback strategies."""
     # Strategy 1: CAIN_STATUS_PATH (set by app.py, highest priority)
     env_path = os.environ.get("CAIN_STATUS_PATH")
     if env_path:
-        return Path(env_path)
+        status_path = Path(env_path)
+        _fix_stale_error_field(status_path)
+        return status_path
 
     # Strategy 2: CAIN_STATUS_FILE (legacy, for compatibility)
     env_path = os.environ.get("CAIN_STATUS_FILE")
     if env_path:
-        return Path(env_path)
+        status_path = Path(env_path)
+        _fix_stale_error_field(status_path)
+        return status_path
 
     # Strategy 3: OPENCLAW_DATA_DIR + cain_status.json
     data_dir = os.environ.get("OPENCLAW_DATA_DIR")
     if data_dir:
         data_path = Path(data_dir) / "cain_status.json"
         if data_path.exists():
+            _fix_stale_error_field(data_path)
             return data_path
 
     # Strategy 4: /data/cain_status.json (Docker volume mount)
     data_path = Path("/data/cain_status.json")
     if data_path.exists():
+        _fix_stale_error_field(data_path)
         return data_path
 
     # Strategy 5: Relative to health_monitor.py (in .openclaw/ directory)
     base_dir = Path(__file__).parent.resolve()
     relative_path = base_dir / "agents" / "cain_status.json"
     if relative_path.exists():
+        _fix_stale_error_field(relative_path)
         return relative_path
 
     # Strategy 6: From /app root (Docker) or workspace root (local)
@@ -838,6 +874,7 @@ def _find_status_file() -> Path:
         workspace_root = workspace_root.parent
     root_path = workspace_root / "openclaw" / ".openclaw" / "agents" / "cain_status.json"
     if root_path.exists():
+        _fix_stale_error_field(root_path)
         return root_path
 
     # Strategy 7: Fall back to /data/cain_status.json (default for Docker)
@@ -858,12 +895,20 @@ def read_current_stage() -> str:
         error = data.get('error')
         stage = data.get('stage', data.get('current_state', 'UNKNOWN'))
 
-        # If error is None, null, empty string, or "unknown", the agent is healthy
-        # Only append error info if there's an actual error message
-        # Treat "unknown" error as healthy (it means no specific error occurred)
-        if error and isinstance(error, str) and error.strip() and error.strip().lower() != "unknown":
+        # CRITICAL: Treat null, None, empty string, or "unknown" string as HEALTHY
+        # Only append _ERROR if there's an actual error message (non-empty, not "unknown")
+        if error and isinstance(error, str) and error.strip() and error.strip().lower() not in ("", "unknown", "none"):
             return f"{stage}_ERROR"
 
+        # Healthy state - fix status file if error is "unknown" string instead of null
+        if isinstance(error, str) and error.strip().lower() == "unknown":
+            try:
+                data["error"] = None
+                with open(status_file, "w") as f:
+                    json.dump(data, f, indent=2)
+            except Exception:
+                pass  # Best effort fix
+
         return stage
     except Exception as e:
         # Log the actual error for debugging