fix(gateway): sanitize agent error messages, validate webhook gh args

Two of the three fixes from PR #6660 (the cli.py reopen_session change is
moot — that raw _conn.execute reopen block no longer exists on main).

- gateway/run.py: stop sending raw type(e).__name__ and str(e)[:300] to
  end users on chat platforms. Exception text from LLM providers can leak
  API URLs, file paths, and partial credentials. Return a generic message;
  keep curated status hints for known HTTP codes; full detail stays in logs.
- gateway/platforms/webhook.py: validate pr_number (positive int) and repo
  (owner/name regex) before passing to the 'gh pr comment' subprocess.
  Payload-controlled values could otherwise inject gh flags (--help, a
  different --repo). List-form subprocess means this is arg injection, not
  shell injection, but validation is still correct.

Co-authored-by: aaronagent <1115117931@qq.com>

gateway/platforms/webhook.py

@@ -938,13 +938,34 @@ class WebhookAdapter(BasePlatformAdapter):
                 success=False, error="Missing repo or pr_number"
             )
 
+        # --- Input validation (prevent CLI argument injection) ---
+        # pr_number must be a positive integer.
+        try:
+            pr_int = int(pr_number)
+            if pr_int <= 0:
+                raise ValueError("non-positive")
+        except (ValueError, TypeError):
+            logger.error(
+                "[webhook] invalid pr_number: %r", pr_number
+            )
+            return SendResult(
+                success=False, error="Invalid pr_number"
+            )
+
+        # repo must match owner/name (alphanumeric, hyphens, underscores, dots).
+        if not re.fullmatch(r"[A-Za-z0-9._-]+/[A-Za-z0-9._-]+", repo):
+            logger.error("[webhook] invalid repo format: %r", repo)
+            return SendResult(
+                success=False, error="Invalid repo format"
+            )
+
         try:
             result = subprocess.run(
                 [
                     "gh",
                     "pr",
                     "comment",
-                    str(pr_number),
+                    str(pr_int),
                     "--repo",
                     repo,
                     "--body",

gateway/run.py

@@ -10910,8 +10910,8 @@ class GatewayRunner(GatewayAuthorizationMixin, GatewayKanbanWatchersMixin, Gatew
                         )
             except Exception:
                 logger.debug("Failed to persist inbound user message after agent exception", exc_info=True)
-            error_type = type(e).__name__
-            error_detail = str(e)[:300] if str(e) else "no details available"
+            # Log full details server-side only; never expose raw exception
+            # types or messages to end users (info-leakage risk).
             status_hint = ""
             status_code = getattr(e, "status_code", None)
             _hist_len = len(history) if 'history' in locals() else 0
@@ -10955,9 +10955,7 @@ class GatewayRunner(GatewayAuthorizationMixin, GatewayKanbanWatchersMixin, Gatew
                 elif status_code == 400:
                     status_hint = " The request was rejected by the API."
             return (
-                f"Sorry, I encountered an error ({error_type}).\n"
-                f"{error_detail}\n"
-                f"{status_hint}"
+                f"Sorry, I encountered an unexpected error.{status_hint}\n"
                 "Try again or use /reset to start a fresh session."
             )
         finally: