## Problem
Codex receives reasoning text from the Responses stream, but FCC does
not emit reasoning-token usage details. Codex reports zero reasoning
tokens even when thinking is present.
## Changes
| Before | After |
| --- | --- |
| Responses usage reported only input, output, and total tokens. |
Responses usage reports input, output, total, and reasoning-token
details when reasoning text exists. |
| Reasoning text had no adapter-owned token estimate. | Reasoning text
gets a Responses-owned best-effort token estimate. |
| Reasoning estimates could exceed reported output tokens. | Reasoning
estimates are capped at reported output tokens. |
| Text-only Responses usage kept the base shape. | Text-only Responses
usage keeps the base shape. |
Codex includes OpenAI tool_search in the tools array; omit it from the Anthropic payload like other passive hosted tools so fcc-codex requests do not fail at conversion.
## Summary
- Split monolithic `core/openai_responses/conversion.py` and `sse.py`
into focused protocol modules (input, output, stream, tools, reasoning,
events, etc.) behind an `OpenAIResponsesAdapter` facade.
- Wire `ClaudeProxyService.create_response()` through the adapter
instead of importing conversion helpers directly, tightening the
API/import boundary.
- Add Codex bridging for Responses `custom_tool_call` items and document
the adapter architecture in `ARCHITECTURE.md`.
## Test plan
- [x] `uv run pytest tests/core/openai_responses/
tests/api/test_openai_responses.py tests/cli/test_adapters.py
tests/contracts/test_import_boundaries.py`
- [x] Full CI via `.\scripts\ci.ps1`
## Summary
- Add `StreamRecoverySession` in
`core/anthropic/stream_recovery_session.py` to centralize early-retry
classification, holdback buffering, retry counting, and flush/discard
behavior shared by Anthropic and OpenAI transports.
- Refactor `AnthropicMessagesTransport` and `OpenAIChatTransport` to use
the shared session instead of duplicating recovery holdback and
early-retry logic.
- Update architecture docs and tests for per-delta overlap trim on
midstream recovery; bump version to 2.2.1.
## Test plan
- [x] `uv run pytest tests/core/anthropic/test_stream_recovery.py`
- [x] `uv run pytest tests/providers/test_anthropic_messages.py
tests/providers/test_streaming_errors.py`
Consolidates the incremental refactor work into a single change set: modular web tools (api/web_tools), native Anthropic request building and SSE block policy, OpenAI conversion and error handling, provider transports and rate limiting, messaging handler and tree queue, safe logging, smoke tests, and broad test coverage.
Alishahryar1