Responses Lite rejects hosted tools at the top level ("responses Lite does
not support top-level tool type web_search"), so Lite requests now carry the
injected web_search tool in an input additional_tools item: extend the
caller's first additional_tools item, or insert one before a trailing
compaction_trigger so the v2 compaction wire keeps the trigger last.
The HTTP passthrough path also runs the shared compatibility normalizer on
/responses/compact; thread the compact flag through so that endpoint is
left untouched, and drop the now-redundant call from the passthrough OAuth
body normalizer.
ChatGPT's Codex endpoint now rejects requests whose input replays a hosted
web_search_call item unless tools declares web_search, failing the stream
with "response protection is unavailable". Codex local context compaction
sends the full history with tools:[], so every compaction after a web search
fails and the session gets stuck in a reconnect loop.
For OAuth transform, passthrough and WebSocket paths, append a cached-only
web_search tool when the history contains web_search_call and no web_search
tool is declared. When the caller offered no tools, pin tool_choice to
"none" so the injected tool cannot be invoked. The /responses/compact wire
shape is left untouched.
Fixes#7927
shaw