fix(vedastro): cut responses are network errors, not 500 (BUG-1504)

_post_json turns IncompleteRead, ConnectionResetError, RemoteDisconnected and
ssl.SSLError raised while reading into URLError, so snapshot dispatch, range
scan and external technique evidence record network_error. The REST health
probe also catches http.client.HTTPException.

Co-Authored-By: Claude Opus 5.5 <noreply@anthropic.com>
Claude-Session: https://claude.ai/code/session_01DbBXoyeZrYn6ryNcSe5Y2Y

scripts/vedastro_rest_bridge.py

@@ -13,6 +13,7 @@ and remains ``official_blocked``.
 from __future__ import annotations
 
 import argparse
+import http.client
 import json
 import os
 import sys
@@ -155,7 +156,8 @@ def probe_calculate_health(*, opener: Any | None = None, timeout: float = 8) ->
             "endpoint": API,
             "transport": "rest",
         }
-    except (urllib.error.URLError, TimeoutError, json.JSONDecodeError, OSError) as error:
+    except (urllib.error.URLError, TimeoutError, json.JSONDecodeError, OSError, http.client.HTTPException) as error:
+        # HTTPException: IncompleteRead and friends when the body is cut (BUG-1504).
         return {
             "status": "official_blocked",
             "reason": type(error).__name__,

scripts/vedastro_service_adapter.py

@@ -14,6 +14,7 @@ import hashlib
 import json
 import os
 import socket
+import ssl
 import subprocess
 import sys
 import threading
@@ -2016,6 +2017,12 @@ def _acquire_free_tier_slot(request_url: str) -> dict[str, Any]:
     }
 
 
+# A connection cut while reading headers or the body. urllib only wraps errors
+# raised while sending, so these reach the caller raw (BUG-1504). RemoteDisconnected
+# is both an HTTPException and a ConnectionResetError.
+_TRANSPORT_READ_ERRORS = (http.client.HTTPException, ConnectionError, ssl.SSLError)
+
+
 def _post_json(endpoint: str, request_preview: dict[str, Any]) -> dict[str, Any] | str:
     request_url, headers, vedastro_payload = _build_live_request(endpoint, request_preview)
     req = request.Request(
@@ -2024,9 +2031,15 @@ def _post_json(endpoint: str, request_preview: dict[str, Any]) -> dict[str, Any]
         headers=headers,
         method="POST",
     )
-    with request.urlopen(req, timeout=_timeout_seconds()) as resp:
-        raw = resp.read().decode("utf-8")
-        return json.loads(raw)
+    try:
+        with request.urlopen(req, timeout=_timeout_seconds()) as resp:
+            raw = resp.read().decode("utf-8")
+    except error.URLError:
+        raise
+    except _TRANSPORT_READ_ERRORS as exc:
+        # Every caller already turns URLError into network_error.
+        raise error.URLError(f"response_read_failed:{type(exc).__name__}") from exc
+    return json.loads(raw)
 
 
 def _retry_status_codes() -> set[int]: