Root cause: IMAGE_MAX_WIDTH and IMAGE_MAX_HEIGHT were set to 2000 — exactly the APIs many-image dimension limit. Images resized to exactly 2000px would get rejected when the conversation accumulated enough images to trigger the API's many-image mode.
Fix: Changed both constants from 2000 to 1568 in src/constants/apiLimits.ts:42-43. This is the resolution the API internally downscales to anyway (documented in the API's encoding/full_encoding.py), so there is zero effective quality loss. All images are now safely below the many-image threshold.
export const IMAGE_MAX_WIDTH = 1568
export const IMAGE_MAX_HEIGHT = 1568
Impact: The single constant change propagates everywhere — imageResizer.ts uses IMAGE_MAX_WIDTH/IMAGE_MAX_HEIGHT for all resize decisions, and the error messages reference these constants dynamically. No other files need changes.
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