The image-part membership test in _payload_chars() ran on every dict in
the request, so a tool JSON Schema with a parameter named "type" (its
value is the sub-schema dict) or a multi-type value like
["string", "null"] raised TypeError: unhashable type before the
request reached the provider. Guard the membership test with
isinstance(str): structured "type" values are payload data, not
content parts, and keep the legacy walk for them.
estimate_request_context_tokens (the stale-stream / non-stream watchdog and Codex TTFB floor
estimator) did len(str(payload)) // 4 over the wire payload, so one native screenshot read as
~100K tokens and selected the 1200s giant-conversation floor while the provider's real prompt
was ~2K (#63871, #76411). Image content parts on both wire shapes (Chat image_url / Responses
input_image) now cost the per-image price learned from provider usage (agent/image_token_cost,
bound per turn; worker threads inherit it via copy_context); base64-looking STRINGS stay text
and tool schemas mentioning image are not images.
A/B, one 300KB screenshot: main estimate 100,545 -> codex floor 1200s / stale 300s; now 2,025
-> floor 0s / stale 180s.
Design and boundary (structured parts only, tools/instructions opaque, plain data-URL strings
stay text) from #76471 by @crdesign8; re-authored to reuse the learned cost instead of a second
fixed constant, and trimmed to 2 invariant tests.
liuhao1024