When ChatGPT Web generates an image as an image_asset_pointer but the pointer
fails to resolve to a downloadable URL (unknown asset scheme, download 403/
expired, oversize), resolveImagePointers returned [] — indistinguishable from
'no image produced' — so the image-generation handler reported the misleading
502 'completed without returning image markdown'. The image genuinely existed
upstream; OmniRoute dropped it silently.
Fix: the executor flags x_image_resolution_failed when a pointer existed but
none resolved (and logs the unresolved asset scheme for follow-up), and the
handler surfaces a truthful 'generated but not retrievable' 502 instead of
'no image markdown'. Adds executorFactory DI for unit testing.
TDD: tests/unit/chatgpt-web-image-silentdrop.test.ts (red -> green), plus the
existing chatgpt-web / image-generation-handler suites stay green.
Reported via community triage (mesh escalated backlog).
286fdf8794