refactor(copilot): narrow exception handling and type context field

- Replace broad `except Exception` with `except (json.JSONDecodeError,
  ValidationError, TypeError, ValueError)` in drain_pending_messages so
  unexpected non-data errors propagate instead of being silently swallowed
- Introduce `PendingMessageContext` Pydantic model to replace the raw
  `dict[str, str]` for the context field, making the url/content contract
  explicit and enabling typed attribute access instead of .get() calls
- Update routes.py to construct PendingMessageContext from the validated
  request dict before passing to PendingMessage
- Update tests to use PendingMessageContext directly

Addresses coderabbitai review comments.

autogpt_platform/backend/backend/api/features/chat/routes.py

@@ -32,6 +32,7 @@ from backend.copilot.model import (
 from backend.copilot.pending_messages import (
     MAX_PENDING_MESSAGES,
     PendingMessage,
+    PendingMessageContext,
     push_pending_message,
 )
 from backend.copilot.rate_limit import (
@@ -1162,7 +1163,7 @@ async def queue_pending_message(
     pending = PendingMessage(
         content=request.message,
         file_ids=sanitized_file_ids,
-        context=request.context,
+        context=PendingMessageContext(**request.context) if request.context else None,
     )
     buffer_length = await push_pending_message(session_id, pending)
 

autogpt_platform/backend/backend/copilot/pending_messages.py

@@ -25,7 +25,7 @@ import json
 import logging
 from typing import Any, cast
 
-from pydantic import BaseModel, Field
+from pydantic import BaseModel, Field, ValidationError
 
 from backend.data.redis_client import get_redis_async
 
@@ -45,12 +45,19 @@ _PENDING_CHANNEL_PREFIX = "copilot:pending:notify:"
 _PENDING_TTL_SECONDS = 3600  # 1 hour — matches stream_ttl default
 
 
+class PendingMessageContext(BaseModel):
+    """Structured page context attached to a pending message."""
+
+    url: str | None = None
+    content: str | None = None
+
+
 class PendingMessage(BaseModel):
     """A user message queued for injection into an in-flight turn."""
 
     content: str = Field(min_length=1, max_length=16_000)
     file_ids: list[str] = Field(default_factory=list)
-    context: dict[str, str] | None = None
+    context: PendingMessageContext | None = None
 
 
 def _buffer_key(session_id: str) -> str:
@@ -153,7 +160,7 @@ async def drain_pending_messages(session_id: str) -> list[PendingMessage]:
     for payload in decoded:
         try:
             messages.append(PendingMessage(**json.loads(payload)))
-        except Exception as e:
+        except (json.JSONDecodeError, ValidationError, TypeError, ValueError) as e:
             logger.warning(
                 "pending_messages: dropping malformed entry for %s: %s",
                 session_id,
@@ -198,12 +205,10 @@ def format_pending_as_user_message(message: PendingMessage) -> dict[str, Any]:
     """
     parts: list[str] = [message.content]
     if message.context:
-        url = message.context.get("url")
-        if url:
-            parts.append(f"\n\n[Page URL: {url}]")
-        page_content = message.context.get("content")
-        if page_content:
-            parts.append(f"\n\n[Page content]\n{page_content}")
+        if message.context.url:
+            parts.append(f"\n\n[Page URL: {message.context.url}]")
+        if message.context.content:
+            parts.append(f"\n\n[Page content]\n{message.context.content}")
     if message.file_ids:
         parts.append(
             "\n\n[Attached files]\n"

autogpt_platform/backend/backend/copilot/pending_messages_test.py

@@ -14,6 +14,7 @@ from backend.copilot import pending_messages as pm_module
 from backend.copilot.pending_messages import (
     MAX_PENDING_MESSAGES,
     PendingMessage,
+    PendingMessageContext,
     clear_pending_messages,
     drain_pending_messages,
     format_pending_as_user_message,
@@ -171,7 +172,7 @@ def test_format_pending_plain_text() -> None:
 def test_format_pending_with_context_url() -> None:
     msg = PendingMessage(
         content="see this page",
-        context={"url": "https://example.com"},
+        context=PendingMessageContext(url="https://example.com"),
     )
     out = format_pending_as_user_message(msg)
     content = out["content"]