fix(blocks): clamp Twitter search start_time to 10 seconds before now (#11461)

## Summary
- Clamp `start_time` to at least 10 seconds before request time (Twitter
API requirement)
- Update input description to document this automatic adjustment
- Fix `serialize_list` to handle `None` data gracefully (exposed by the
fix)

## Background
Twitter API returns `400 Bad Request` when `start_time` is less than 10
seconds before the request time. Users providing current/future times
would hit this error.

**Sentry Issue:**
[BUILDER-3PG](https://significant-gravitas.sentry.io/issues/6919685270/)

## Affected Blocks
- `TwitterSearchRecentTweetsBlock`
- `TwitterGetUserMentionsBlock`
- `TwitterGetHomeTimelineBlock`
- `TwitterGetUserTweetsBlock`

## Test plan
- [x] Tested `TwitterSearchRecentTweetsBlock` with current time as
`start_time`
- [x] Verified clamping works and API call succeeds
- [x] Verified "No tweets found" is returned correctly when search
window has no results

🤖 Generated with [Claude Code](https://claude.com/claude-code)

Co-authored-by: Claude <noreply@anthropic.com>
Co-authored-by: Abhimanyu Yadav <122007096+Abhi1992002@users.noreply.github.com>

autogpt_platform/backend/backend/blocks/twitter/_builders.py

@@ -1,4 +1,4 @@
-from datetime import datetime
+from datetime import datetime, timedelta, timezone
 from typing import Any, Dict
 
 from backend.blocks.twitter._mappers import (
@@ -237,6 +237,12 @@ class TweetDurationBuilder:
 
     def add_start_time(self, start_time: datetime | None):
         if start_time:
+            # Twitter API requires start_time to be at least 10 seconds before now
+            max_start_time = datetime.now(timezone.utc) - timedelta(seconds=10)
+            if start_time.tzinfo is None:
+                start_time = start_time.replace(tzinfo=timezone.utc)
+            if start_time > max_start_time:
+                start_time = max_start_time
             self.params["start_time"] = start_time
         return self
 

autogpt_platform/backend/backend/blocks/twitter/_serializer.py

@@ -51,8 +51,10 @@ class ResponseDataSerializer(BaseSerializer):
         return serialized_item
 
     @classmethod
-    def serialize_list(cls, data: List[Dict[str, Any]]) -> List[Dict[str, Any]]:
+    def serialize_list(cls, data: List[Dict[str, Any]] | None) -> List[Dict[str, Any]]:
         """Serializes a list of dictionary items"""
+        if not data:
+            return []
         return [cls.serialize_dict(item) for item in data]
 
 

autogpt_platform/backend/backend/blocks/twitter/_types.py

@@ -408,7 +408,7 @@ class ListExpansionInputs(BlockSchemaInput):
 
 class TweetTimeWindowInputs(BlockSchemaInput):
     start_time: datetime | None = SchemaField(
-        description="Start time in YYYY-MM-DDTHH:mm:ssZ format",
+        description="Start time in YYYY-MM-DDTHH:mm:ssZ format. If set to a time less than 10 seconds ago, it will be automatically adjusted to 10 seconds ago (Twitter API requirement).",
         placeholder="Enter start time",
         default=None,
         advanced=False,