Migrate handler layer to HTTP types (PR 12)

[prk-Jr]

Summary

• Move the PR 12 handler boundary to http request/response types so core handlers no longer depend on Fastly request/response APIs.
• Keep Fastly isolated to the adapter entry/exit path and the still-unmigrated integration/provider boundary, which keeps PR 13 scope separate.
• Lock the migrated surface with tests and migration guards so later changes do not accidentally reintroduce handler-layer Fastly types.

Changes

File	Change
crates/trusted-server-adapter-fastly/src/main.rs	Move the conversion boundary to the adapter entry/exit path and route core handlers with HTTP-native requests and responses.
crates/trusted-server-core/src/auction/endpoints.rs	Migrate the /auction handler to http types and rebuild a Fastly request only at the provider-facing AuctionContext boundary.
crates/trusted-server-core/src/auction/formats.rs	Consume HTTP requests directly and return HTTP auction responses.
crates/trusted-server-core/src/auction/orchestrator.rs	Keep provider parsing Fastly-based while making the provider response conversion explicit in the orchestrator.
crates/trusted-server-core/src/compat.rs	Add the minimal borrowed HTTP-to-Fastly request bridge needed for the remaining provider boundary.
crates/trusted-server-core/src/geo.rs	Make response header injection operate on HTTP responses.
crates/trusted-server-core/src/integrations/google_tag_manager.rs	Adapt the integration boundary so the shared proxy helper can stay HTTP-native while the integration trait remains Fastly-based.
crates/trusted-server-core/src/integrations/gpt.rs	Adapt the integration boundary so the shared proxy helper can stay HTTP-native while the integration trait remains Fastly-based.
crates/trusted-server-core/src/integrations/testlight.rs	Adapt the integration boundary so the shared proxy helper can stay HTTP-native while the integration trait remains Fastly-based.
crates/trusted-server-core/src/migration_guards.rs	Extend the guard to cover the handler modules migrated in PR 12.
crates/trusted-server-core/src/proxy.rs	Migrate first-party proxy/click/sign/rebuild handlers and response rewriting to HTTP request/response types.
crates/trusted-server-core/src/publisher.rs	Migrate publisher handlers to HTTP types and use the platform HTTP client for publisher-origin fetches.
crates/trusted-server-core/src/request_signing/endpoints.rs	Migrate request-signing and admin handlers to HTTP request/response types.

Closes

Closes #493

Test plan

• cargo test --workspace
• cargo clippy --workspace --all-targets --all-features -- -D warnings
• cargo fmt --all -- --check
• JS tests: cd crates/js/lib && npx vitest run (not run; no JS/TS files changed)
• JS format: cd crates/js/lib && npm run format
• Docs format: cd docs && npm run format
• WASM build: cargo build --package trusted-server-adapter-fastly --release --target wasm32-wasip1
• Manual testing via fastly compute serve
• Other: verified remaining Fastly usage is limited to the adapter boundary and the still-unmigrated integration/provider boundary

Checklist

• Changes follow CLAUDE.md conventions
• No unwrap() in production code — use expect("should ...")
• Uses tracing macros (not println!)
• New code has tests
• No secrets or credentials committed

[ChristianPavilonis]

Summary

Clean migration of the handler layer from fastly::Request/fastly::Response to http::Request<EdgeBody>/http::Response<EdgeBody>. The conversion boundary is pushed to the adapter entry/exit and the still-unmigrated integration trait boundary. Well-tested, CI passes.

Non-blocking

♻️ refactor

• Duplicate error-to-response functions: http_error_response (new, returns HttpResponse) and to_error_response (existing, returns FastlyResponse) implement identical logic with different return types. Expected migration scaffolding — track for cleanup in PR 15 when Fastly types are fully removed. (main.rs:255-267 / error.rs:10)

CI Status

• integration tests: PASS
• browser integration tests: PASS
• prepare integration artifacts: PASS

[aram356]

Summary

Solid mechanical migration of the handler layer from Fastly request/response types to http crate types. The conversion boundary is cleanly pushed to the adapter entry point, with proper compat shims for the still-unmigrated integration/provider boundary.

Non-blocking

🤔 thinking

• platform_response_to_fastly duplicated into orchestrator.rs: Copy-pasted from proxy.rs rather than shared via compat.rs. Two separate HTTP→Fastly response paths risk divergence (this copy uses set_header which drops multi-value headers; compat::to_fastly_response doesn't). (orchestrator.rs:15)
• sync→async handle_publisher_request: Public API signature change — only caller uses block_on so it works, but worth documenting. (publisher.rs:305)

♻️ refactor

• Cursor::new(body.into_bytes()) repeated 4 times: Could extract a small body_as_reader helper to centralize body materialization. (proxy.rs:175, publisher.rs:228,246,263)

🌱 seedling

• DEFAULT_PUBLISHER_FIRST_BYTE_TIMEOUT hardcoded at 15s: Good to make it explicit, but may need to be configurable per deployment. (publisher.rs:22)

📝 note

• Integration proxy double-conversion: GTM, GPT, testlight each wrap proxy_request with from_fastly_request/to_fastly_response, copying bodies twice. Expected for the PR 13 boundary.

⛏ nitpick

• Inconsistent test type alias style: proxy.rs tests use HttpMethod/HttpStatusCode prefixes; publisher.rs tests don't. The unprefixed style is cleaner.

CI Status

• integration tests: PASS
• browser integration tests: PASS
• prepare integration artifacts: PASS

[aram356]

Summary

Mechanically sound migration of the handler layer from fastly::{Request,Response} to http::{Request,Response}<EdgeBody>. The adapter entry/exit is now the only fastly conversion site for handlers, and the migration guard test is extended to lock this in. Overall high quality — a handful of concrete concerns to address before merge, mostly around silent failure modes that the type migration makes easier to miss.

Blocking

🔧 wrench

• Silent EdgeBody::Stream drop — compat.rs:132-134 and auction/orchestrator.rs:29-32 log a warning and drop the body on the Stream variant. No test pins this behavior; debug_assert! only fires in debug. If a streaming body ever reaches this boundary, the client gets an empty 200.
• Unbounded request body → String — proxy.rs:889 and proxy.rs:1003 do String::from_utf8(req.into_body().into_bytes().to_vec()) with no size cap. OOM/DoS risk on hostile POST.
• Silent JSON serialization fallback — proxy.rs:1156 returns {} on serde_json::to_string failure instead of propagating an error.
• Geo lookup moved before auth — main.rs:95-110 runs the geo lookup on every request, including ones that will immediately 401. Confirm this is intentional.

❓ question

• Integration trait still fastly-based — main.rs:182-196 pays a full http → fastly → http round-trip per integration request. Deferred to PR 13? If so, please leave a // TODO(PR13) marker.
• to_fastly_request_ref drops body — auction/endpoints.rs:90 call site has no comment explaining why the empty body is safe. Please add one line so this invariant doesn't regress.

Non-blocking

🤔 thinking

• Multi-valued Set-Cookie survival through rebuild_response_with_body (proxy.rs:138) — add a test, also consider mem::take to avoid the header clone.
• Invalid settings.response_headers are silently warn-skipped at request time (main.rs:250-262); CLAUDE.md prefers startup-time validation.

♻️ refactor

• migration_guards.rs uses substring matching on "fastly::Request" — prefer a \bfastly::(Request|Response|http::(Method|StatusCode))\b regex to avoid false positives on future string literals or doc comments.

🌱 seedling

• End-to-end streaming (EdgeBody::Stream) is effectively unreachable today. Worth a follow-up to preserve streaming semantics through publisher fetch → rewrite → response once PR 13 lands.

📝 note

• publisher.rs:325 vs publisher.rs:361 — inconsistent services.client_info() vs services.client_info.client_ip access idiom.

👍 praise

• Tight adapter boundary in main.rs:89-120: one from_fastly_request/to_fastly_response pair framing route_request. Very clean.
• insert_geo_header warn-and-continue is the right shape for derived geo data.
• Migration guard extended to cover the handler layer — exactly the right regression gate for this refactor.

CI Status

• fmt: PASS
• clippy: PASS
• rust tests: PASS
• js tests: PASS

(All three GitHub Actions checks — browser integration tests, integration tests, prepare integration artifacts — are green.)

• publisher.rs:325 vs publisher.rs:361 — inconsistent services.client_info() (method) vs services.client_info.client_ip (field) access idiom. Please pick one.