Full schema field coverage is tracked in `docs/api/format-field-coverage-matrix.md`. That matrix is generated from the schema inventory in `docs/api/provider-interface-definitions.md` by `python3 docs/api/generate_format_field_coverage.py` and gives every documented OpenAI, Claude, and Gemini schema field a handling status. “Handled” means mapped, same-format/native preserved, extension-preserved, blocked with a structured error, or explicitly marked outside the canonical conversion surface.
Provider schema refresh is not a runtime dependency. Same-format runtime paths do not use this matrix; they bypass canonical conversion. Same-format canonical roundtrip must preserve unrecognized provider fields through provider extension namespaces. Cross-format conversion is capability-based: only explicitly mapped fields are emitted, and newly discovered or unknown provider fields fail closed with `UnauditedField` until a lossless mapping is audited.
| Reporting | Added `ConversionReport` with field statuses. Runtime reports remain conversion-operation oriented; exhaustive nested schema coverage is enforced by `format-field-coverage-matrix.md`. |
| Source schema coverage | Cross-format request conversion rejects unknown source root fields before emit. Every documented schema field is covered by the field coverage matrix. |
| Tool schema roundtrip | Claude `input_schema` and Gemini `functionDeclarations.parameters` preserve raw same-format schema through provider-specific extensions. |
| Tool result ids | Chat `tool_call_id`, Responses `call_id`, Claude `tool_use_id`, and Gemini `functionResponse.id` are mapped through canonical tool IDs. |
## OpenAI Chat -> OpenAI Responses
| Chat field | Canonical handling | Responses output | Status |
Claude to OpenAI Chat, Claude to OpenAI Responses, and the reverse directions are included in the field coverage matrix. Runtime strict guards cover request root fields, provider extension namespaces, thinking/cache/tool-result hazards, and target generation-field gaps. Fields without a lossless target equivalent fail closed instead of being dropped.
Gemini to OpenAI Chat, Gemini to OpenAI Responses, Gemini to Claude, and reverse generation paths are included in the field coverage matrix. Gemini-only request fields are preserved same-format and blocked cross-format unless the target mapping is explicitly audited.
Embedding and rerank request parse/emit capability and strict target guards are implemented. Provider schema fields outside these canonical conversion surfaces are marked `not-in-conversion-surface` in the field coverage matrix instead of being left implicit.
Cross-format sync response conversion now validates source stop/finish/status
enums before emitting a target body. Same-format runtime response passthrough is
still outside canonical conversion.
| Source field | Target risk | Current behavior | Status |
| --- | --- | --- | --- |
| Same-format response raw stop/status fields | canonical emitters would otherwise normalize unknown enum/status to default target stop values | raw OpenAI Chat `finish_reason`, OpenAI Responses `status`, Claude `stop_reason`/`stop_sequence`, and Gemini `finishReason` are preserved through provider extension metadata | extension-preserved |
| OpenAI Chat `choices[].finish_reason` | unknown value would otherwise emit as target normal stop | valid Chat enum required; unknown values fail with `InvalidEnumValue` | invalid-enum |
| OpenAI Responses `status` | `queued`, `in_progress`, and `cancelled` have no sync target equivalent | non-terminal valid states fail with `LossyConversionBlocked`; invalid states fail with `InvalidEnumValue` | lossy-blocked / invalid-enum |
| OpenAI Responses `incomplete_details.reason=content_filter` | previously mapped to max tokens/`length` | maps to canonical content filter and emits Chat `content_filter` / Claude `content_filtered` / Gemini `SAFETY` | mapped |
| Claude `stop_reason` | unknown value would otherwise emit as target normal stop | valid known stop enum required for cross-format conversion | invalid-enum |
| Gemini `candidates[].finishReason` | known-but-unmappable reasons would otherwise emit as target normal stop | mappable safety/max/stop reasons convert; known unmappable values such as `OTHER`, `MALFORMED_FUNCTION_CALL`, `UNEXPECTED_TOOL_CALL`, `MISSING_THOUGHT_SIGNATURE`, and `MALFORMED_RESPONSE` fail with `LossyConversionBlocked`; future unknown values fail with `InvalidEnumValue` | lossy-blocked / invalid-enum |
| Provider parsers | OpenAI Chat, OpenAI Responses, Claude, and Gemini unknown stream payloads become `CanonicalStreamEvent::UnknownEvent` | mapped |
| Cross-format stream matrix | Unknown canonical stream events emit a target-format error SSE with `unsupported_stream_event` and terminate conversion | lossy-blocked |
| Stream finish reason guard | Unknown OpenAI finish reasons, unknown Claude `stop_reason`, and Gemini known-but-unmappable `finishReason` values such as `OTHER` are preserved as raw canonical finish strings, then blocked by the matrix with `unsupported_finish_reason` | lossy-blocked |
| OpenAI Responses stream target | Canonical `length` and `content_filter` terminal reasons emit `response.incomplete` with `incomplete_details.reason=max_output_tokens` or `content_filter` instead of `response.completed` | mapped |
| Runtime strict fallback guard | `UnauditedField`, `InvalidEnumValue`, `UnsupportedField`, `LossyConversionBlocked`, and `InvalidTargetField` from registry response conversion are not allowed to fall through legacy conversion helpers | lossy-blocked |
