## Why
Standard MCP forms can require user-entered values even when tool permissions are
otherwise auto-approved in full-access sessions.
## What changed
- Recognize the `openai/standard-form-input` client extension and surface
non-approval forms in full-access, user-initiated root threads.
- Keep approval forms, automation and subagent threads, headless sessions, and
clients without the capability on their existing decline or review paths.
- Treat the capability as client-only so it is not advertised to MCP servers,
and enable it after session startup so required servers cannot block startup
waiting for form input.
## Testing
Add unit and app-server coverage for accepted form round trips, declined cases,
approval metadata safeguards, resumed threads, and extension filtering.
GitOrigin-RevId: 053bfe397a5c79eceef90a81d13e2aca6353af43
## Why
App-server clients need to advertise structured MCP extension settings, including supported MCP App UI MIME types, rather than only opting into OpenAI form elicitation with a boolean.
## What changed
- Add an `extensions` map to initialize capabilities and preserve `mcpServerOpenaiFormElicitation` as a legacy alias for `openai/form`.
- Capture the declared extension profile when a thread is started, resumed, or forked, propagate it to subagents, and advertise it to downstream MCP servers during initialization.
- Keep the profile stable for the lifetime of the loaded session instead of changing it on later turns or direct tool calls.
## Testing
- Cover extension conversion, downstream MCP initialization, session isolation, legacy form support, and subagent inheritance.
GitOrigin-RevId: fbcedbb74ce788e574b0f884a4c45c4cedb9de54
mchen-oai