Preserve native K1 error causes and distinguish Wi-Fi actions

src/k1link/device_plugins/xgrids_k1/node_bridge.py

@@ -37,6 +37,29 @@ ATTESTATION = {
 }
 
 
+def failure_locations(error: BaseException) -> str:
+    """Bounded causal stack, excluding messages, source lines and frame locals.
+
+    The facade deliberately wraps native transport errors. Logging only the
+    outer stack loses the actual OS failure boundary on journalled responses.
+    """
+    chain: list[str] = []
+    seen: set[int] = set()
+    current: BaseException | None = error
+    while current is not None and id(current) not in seen and len(chain) < 6:
+        seen.add(id(current))
+        frames = list(traceback.walk_tb(current.__traceback__))[-10:]
+        locations = ";".join(
+            f"{Path(frame.f_code.co_filename).name}:{frame.f_code.co_name}:{line}"
+            for frame, line in frames
+        )
+        chain.append(f"{type(current).__name__}[{locations}]")
+        current = current.__cause__ or (
+            None if current.__suppress_context__ else current.__context__
+        )
+    return " <- ".join(chain)
+
+
 class NodeEnrollmentRejected(ValueError):
     """A host admission failure proven to precede any device invocation."""
 
@@ -152,14 +175,11 @@ class NodeBridge:
             # results, so the HTTP exception logger never sees them. Record
             # only source locations here; exception text may contain a frame.
             logging.getLogger(__name__).warning(
-                "K1 journalled invocation failed: action=%s operation=%s exception=%s locations=%s",
+                "K1 journalled invocation failed: action=%s operation=%s exception=%s chain=%s",
                 action,
                 identifier,
                 type(error).__name__,
-                ";".join(
-                    f"{Path(frame.filename).name}:{frame.name}:{frame.lineno}"
-                    for frame in traceback.extract_tb(error.__traceback__)[-10:]
-                ),
+                failure_locations(error),
             )
             # Read the exact result after a failure; never repeat an invocation
             # or interpret an exception as evidence that a command was unsent.
@@ -346,15 +366,12 @@ def create_app(repository_root: Path):
             # text, source lines, local variables, payloads or credentials.
             action = body.get("action") if isinstance(body, dict) else None
             logging.getLogger(__name__).warning(
-                "K1 operation failed: action=%s exception=%s locations=%s",
+                "K1 operation failed: action=%s exception=%s chain=%s",
                 action
                 if isinstance(action, str) and action in {"scan", "networks", "connect", "verify"}
                 else "invalid",
                 type(error).__name__,
-                ";".join(
-                    f"{Path(frame.filename).name}:{frame.name}:{frame.lineno}"
-                    for frame in traceback.extract_tb(error.__traceback__)[-8:]
-                ),
+                failure_locations(error),
             )
             return JSONResponse(
                 {