[cunninghamcard-bit]

Requested by li

Summary

Before: each model's private config carries the AI SDK's provider callbacks as Rust closures: a url() closure that builds the endpoint, a headers() closure that adds auth and fixed headers, endpoint closures for Vertex, Bedrock and Polly, supported-URL closures, and a provider-name match that picks the Alibaba or Moonshot AI usage shape.

After: package-private configs hold plain data, and where a shared layer needs a vendor's behaviour, the shared layer defines a small trait and the vendor implements it in its own module.

• Inside one package: base URLs are enums (OpenAIUrl, MessagesUrl, AnthropicEndpoint, the compatible BaseUrl::Preset); provider headers are ProviderHeaders / EndpointHeaders.
• Across packages: shared defines ResolveEndpoint (with HttpEndpoint for the common case); the Vertex Gemini, Bedrock and Polly endpoints implement it in vertex/, bedrock/ and aws_polly/. openai_compatible defines ResolveBaseUrl and ResolveFetchHeaders; the Vertex partner sub-providers implement them in vertex/. Google's supported-URL patterns are passed in as a function.
• Usage: the Alibaba and Moonshot AI converters live with their registry rows in preset.rs and reach the chat model through the existing convert_usage hook, chosen by the row's profile.convert_usage rather than the provider name.
• ChatSettings::error_structure stays a capturing Arc<dyn Fn>, the same shape as convert_usage.
• SigV4Fetch::with_clock takes a fn pointer.

scripts/check_provider_boundaries.sh gains a rule: code in shared/ and openai_compatible/ may only name the shared layers, preset and runtime_decision, so vendor modules added later are caught too. Special auth stays composed inside each vendor package (D11). Public settings and public JSON do not change.

This re-derives the earlier "provider config is plain data" layer of the RFC-0036 stack (branch rfc-0036/provider-config) onto the migrated code, keeping what the project decided to keep: compat transformRequestBody, metadataExtractor, supportsMultiPartToolContent and specification_version.

Type of change

• Bug fix (non-breaking)
• New feature (non-breaking)
• Breaking change
• New provider
• New / updated binding
• Docs / RFC

Refactor of private internals.

Checklist

• cargo fmt --all -- --check passes
• cargo clippy --workspace --all-targets -- -D warnings passes
• cargo test --workspace passes (cassette playback — no network/keys)
• Added or updated cassette tests / contract fixtures for behavior changes
• Updated relevant docs (README.md, docs/, rfc/, bindings/README.md)
• Commit messages follow Conventional Commits

Notes for reviewers

• Position: base master; [10/13] ([10/13] refactor: tool-call repair is a trait #258) is merged, and this is the next PR of the Rust-adaptation series.
• Direction: structure only. Every public setting, request, error and JSON field is unchanged, including the camelCase provider-config JSON (baseUrl, with base_url still accepted), the by-name provider entries, the C ABI, the bindings and the generated TS types.
• Dependencies point one way: no shared → vertex/bedrock/aws_polly/google or openai_compatible → vertex imports; the first version of this PR had them and the boundary rule now forbids them.
• Kept caller closures: transform_request_body, generate_id, and the compatible supported_urls, convert_usage, error_structure and metadata_extractor.
• Not ported from the old layer, because those parts change behaviour or the public API: the by-name/FFI config path, a feature commit, the removal of transform_request_body, the narrowing of generate_id, and the rewrite of the compatible public settings.
• Edge case: PresetDescriptor gains a pub(crate) field. Code outside the crate could previously build one with a struct literal; it is built from the registry JSON in practice. Noted in CHANGELOG.
• Docs: CHANGELOG and docs/contributing/adding-a-provider.md updated.

Verification

Check	Result
cargo test --workspace	3194 passed, 0 failed, 7 ignored: the same per test binary as #258, plus the new SearXNG and DataForSEO env tests (the ts-rs export tests run only under the ts-export feature since [1/8])
Upstream fixture replays ({openai,anthropic,google,openai_compatible}_factory_test)	unchanged
Test edits	decision_support.rs native_decision_url_passes_endpoint_to_url_callback builds its config with ProviderHeaders and OpenAIUrl::Base (the url closure it overrode no longer exists); a_lazy_base_url_is_evaluated_per_request_and_its_error_fails_the_request uses a preset whose base URL comes from an env var. New: searxng_test.rs instance_url_comes_from_searxng_url_per_request covers the BaseUrl::Env path (not in the request differential: search providers have no cassettes); the DataForSEO EndpointHeaders::Basic path is covered by the existing do_search_sends_correct_basic_auth_header, and dataforseo_test.rs login_comes_from_dataforseo_login_per_request covers the login read from DATAFORSEO_LOGIN per request (missing: LoadApiKey, no request sent)
Boundary rule	reports all 8 vendor references on the first version of this PR; passes now
Old vs new, request by request	#258 against #260 (this PR and the next together): 2,542 cassettes plus all 282 registry presets replayed through every public language-model route with a recording transport. 20,173 requests (URL, headers, body), 8,464 generate results and 2,497 errors compared: 0 differ once the process-wide source-N / id-N counters of the Responses code are normalised. Not covered: cassettes for non-language-model endpoints, response bodies over 256 KiB, and search, speech, transcription, image and video providers (no cassettes). The probe (one test file copied into both worktrees, plus a diff script) is not committed; it can be shared on request
Gate	fmt, clippy, rustdoc -D warnings, gen_ts_types.py --check, gen_providers_doc.py --check, check_provider_boundaries.sh pass on stable 1.99

[cunninghamcard-bit]

谢谢评审。这一层已随整套栈更新，请以更新后的为准。

你提到	我们的处理	位置
（我们自己的改动）shared 和 openai_compatible 原先反向依赖厂商模块	共享层定义 ResolveEndpoint、ResolveBaseUrl、ResolveFetchHeaders，各厂商自己实现，边界检查脚本加了对应规则；Alibaba 和 Moonshot 的 usage 换算跟着 registry 行放进 preset.rs；UsageDialect 去掉	aimux-providers/src/shared/、preset.rs、scripts/check_provider_boundaries.sh
SearXNG 从 SEARXNG_URL 读地址、DataForSEO 用 Basic 头，这两条新路径应有测试	都补了。SearXNG：instance_url_comes_from_searxng_url_per_request，设了变量请求发到 mock，删掉后返回 LoadSetting 且不发请求。DataForSEO：Basic 头原有 do_search_sends_correct_basic_auth_header 覆盖；从 DATAFORSEO_LOGIN 读 login 的分支新增 login_comes_from_dataforseo_login_per_request，设了变量带正确 Basic 头，删掉后返回 LoadApiKey 且不发请求	aimux-providers/tests/searxng_test.rs、dataforseo_test.rs
CHANGELOG 应写明 PresetDescriptor 多了 crate 私有字段，crate 外不能再用结构体字面量构造	已补这一句	CHANGELOG.md
validate_base_url 允许地址带 userinfo，以后收紧校验时要记得保留	确认是有意保留（自托管服务的 basic-auth），日后收紧时显式保留这一条	无代码改动

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