* fix(agent): strip vision markers from history for non-vision providers
When a user sends an image via Telegram to a non-vision provider, the
`[IMAGE:/path]` marker gets stored in the JSONL session file. Previously,
the rollback only removed it from in-memory history, not from the JSONL
file. On restart, the marker was reloaded and permanently broke the
conversation.
Two fixes:
1. `rollback_orphan_user_turn` now also calls `remove_last` on the
session store so the poisoned entry is removed from disk.
2. When building history for a non-vision provider, `[IMAGE:]` markers
are stripped from older history messages (and empty turns are dropped).
Fixes#3674
* fix(agent): only strip vision markers from older history, not current message
The initial fix stripped [IMAGE:] markers from all prior_turns including
the current message, which caused the vision check to never fire. Now
only strip from turns before the last one (the current request), so
fresh image sends still get a proper vision capability error.
84470a2dd2