refactor(core)!: provider results carry request and response information as upstream does

[cunninghamcard-bit]

What

Move language-model request and response information into the provider result objects and carry it into the call-layer results, following LanguageModelV4GenerateResult, LanguageModelV4StreamResult, generateText, and streamText. This pull request is based on rfc-0036/provider-prompt-types and precedes rfc-0036/factory-test-removal. It removes the old flat JSON adapter, separates public text-stream chunks from provider chunks, and absorbs provider response metadata into the completed step. Provider implementations and language bindings are updated for these changes.

Before and after

Type or behavior	Before	After and upstream reference
Provider generation result	GenerateResultWire flattened request body and response headers during serialization	GenerateResult serializes directly with optional request: RequestInfo and response: ResponseInfo, corresponding to LanguageModelV4GenerateResult
Provider response types	Separate GenerateResponse and StreamResponse types	Shared ResponseInfo contains optional id, timestamp, model id, headers, and body; StreamResponseInfo contains optional headers, as in LanguageModelV4StreamResult
Non-streaming call result	No top-level request; response held metadata alone	GenerateTextResult.request carries the provider request and response carries metadata, headers, and body, following generate-text.ts; missing metadata gets call-layer defaults
GenerateTextResult.raw	A second serialization path preserved the earlier flat JSON	The field uses GenerateResult directly. The call layer moves request and response into its top-level fields, leaving those fields empty in raw
Public stream chunks	TextStreamPart was an alias of the provider union and exposed response metadata events	A distinct TextStreamPart enum receives content chunks; provider metadata is absorbed and exposed through FinishStep.response, following stream-text.ts
Incomplete stream without output	Consumption used a generic invalid-response error; the direct stream could synthesize successful metadata	The direct stream emits NoOutputGenerated, and consumption returns that error, following the upstream NoOutputGeneratedError path
Stream aggregation	Request and response headers were lost	StreamTextResultAggregated carries request information and the last step's response metadata and headers
OpenAI Responses and Azure streaming request information	Returned request body included stream: true	Only the HTTP body gets stream: true; the returned request body excludes it, following openai-responses-language-model.ts

Upstream's Date and number types are compile-time constraints, not runtime validation in these result types. Rust retains String timestamps and u32 token counts. Request and response bodies remain Value, which cannot represent every value allowed by upstream's unknown.

Tests

Earlier deletions of self-generated contract tests and hand-written tests remain in the stack. This branch retains upstream-ported tests and cassette replays; cassette_full_test.rs now matches TextStreamPart. Existing end-to-end stream assertions are migrated to FinishStep followed by Finish, and output round-trip callers use generate_text_result_to_chat_completion to read call-layer response metadata. Those hand-written end-to-end and round-trip test files still exist in this branch; this pull request does not claim they were deleted or ported from upstream. Cassette payloads and fixtures/ are unchanged.

Not in this pull request

• Serde naming remains pending the maintainer's decision: snake_case fields, PascalCase external tags, Option values serialized as null where not omitted, and generated Node types with required-nullable fields. These representations are not claimed to match upstream's optional properties.
• The call-layer ModelMessage tool-result shape remains pending the maintainer's decision. The new public stream enum still carries the provider ToolResult payload; it does not complete the call-layer tool-result and error separation. The stream also retains its Rust Result error channel.
• Bedrock generation still exposes the full response body here, although upstream's Converse result omits it. This is fixed on rfc-0036/vendor-alignment.
• Other model families' result contracts are outside this language-model result change; they need separate upstream comparison.
• Removal of the remaining hand-written provider end-to-end and output round-trip tests is outside this result migration; their continued presence is not evidence of upstream behavior.

Not verified

No cargo command or runtime test was run for this documentation update. Go, Java, Kotlin, Swift, and Flutter files edited on this branch were not compiled locally. Node npm test and Python pytest were not run. CI YAML was only syntax-checked; CI execution is not verified. Providers without corresponding source in the local upstream packages were not independently checked for behavioral parity.

Verification

Gate on the final commit 6a1da337: cargo fmt --check, cargo clippy --workspace --all-targets -D warnings, cargo doc, tests of core, provider-utils, providers, ffi, web, replay and cli: 2,316 passed, 0 failed; Node and Python bindings cargo check; provider boundary script; gen_ts_types.py --check, gen_providers_doc.py --check. Cassettes and fixtures/aisdk unchanged relative to the base. 61 files, +986 / −627.

🤖 Generated with Claude Code

https://claude.ai/code/session_01WGwanvo9WLU9HWD7sRR8TS