The eligibility gate in grokChatResponsesBridgeEligibility rejected any
structured content (arrays), including standard OpenAI image_url parts.
This forced image-bearing requests to fall back to raw Chat Completions
forwarding, where non-Composer models have no image bridge — silently
dropping the images or causing upstream errors.
Changes:
- Allow content arrays containing only text and image_url parts to pass
eligibility, so ChatCompletionsToResponses can convert them to
input_image parts that Grok vision models natively support.
- Force image-bearing requests to use Responses even when no prompt
cache identity is available, since the raw path cannot forward images
for non-Composer models.
- Add grokChatStructuredContentBridgeable helper with conservative
validation: unknown part types (e.g. input_audio) still fall back.
- Update tests: image_url content is now bridgeable; add cases for
text+image, text-only arrays, unknown parts, and empty arrays.
lenzhang
d5bc576b4f