xAI's /responses endpoint rejects pattern and format JSON Schema keywords
in tool schemas with HTTP 400 'Invalid arguments passed to the model'.
The existing strip_pattern_and_format() only walked OpenAI-format tools
({'function': {'parameters': ...}}), missing Responses-format shapes
({'name': ..., 'parameters': ...}) used by codex_responses API mode.
This shows up most often with MCP-derived tools that carry validation
keywords (e.g. domain pattern regex in firecrawl, format: date-time)
through to the wire.
Extends the walk to handle both shapes. Auto-strip wiring is applied
separately in chat_completion_helpers (post-refactor location).
Closes#27197
zccyman
2551f08130