Why: Uploaded images never reached the model, so a text-only chat model could be asked to read a picture it cannot see.
Evidence: go test ./internal/... passed locally before this commit. Image-link rejection is covered by vision package tests.
Impact: Current-turn attachments and fetched image links become image input. History keeps a text placeholder. Image turns swap to the configured vision model when the chat model is not in the capable list, and fallbacks are filtered the same way.
Refs: Agent-System-Dev feature/four-model-vision
Co-authored-by: Cursor <cursoragent@cursor.com>
weichenandCursor
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