Migrate utility layer to HTTP types (PR 11)

[prk-Jr]

Summary

• Migrate the PR11 utility layer off direct fastly::Request/fastly::Response usage so core helpers can operate on http::{Request, Response} and edgezero_core::Body.
• Add a temporary compat bridge at Fastly boundaries so handlers and integrations can keep working while later migration PRs move the remaining call stack.
• Lock in the migration with focused compat tests and a guard test that prevents the migrated utility modules from drifting back to Fastly request/response types.

Changes

File	Change
Cargo.toml	Add the workspace mime dependency used by migrated HTTP response helpers.
Cargo.lock	Record the new mime dependency.
crates/trusted-server-adapter-fastly/src/main.rs	Route forwarded-header sanitization and basic-auth response conversion through the new compat boundary.
crates/trusted-server-core/Cargo.toml	Add the core crate's mime workspace dependency.
crates/trusted-server-core/src/auction/endpoints.rs	Convert auction utility calls to use the HTTP request compat bridge for synthetic ID and consent handling.
crates/trusted-server-core/src/auction/formats.rs	Bridge Fastly requests into migrated synthetic ID generation helpers.
crates/trusted-server-core/src/auth.rs	Migrate basic-auth enforcement to http::Request/Response and update tests to HTTP builders.
crates/trusted-server-core/src/compat.rs	Add Fastly↔HTTP request/response conversions plus temporary Fastly boundary shims for headers, cookies, and synthetic cookie handling.
crates/trusted-server-core/src/consent/extraction.rs	Migrate consent signal extraction to http::Request<EdgeBody>.
crates/trusted-server-core/src/consent/mod.rs	Move consent pipeline input types and tests onto HTTP request types.
crates/trusted-server-core/src/cookies.rs	Migrate cookie parsing/forwarding and synthetic cookie response helpers to HTTP request/response types.
crates/trusted-server-core/src/http_util.rs	Migrate request/response helpers to HTTP types, preserve duplicate headers, and keep request-info logic on ClientInfo.
crates/trusted-server-core/src/integrations/lockr.rs	Use Fastly compat shims for header/cookie forwarding at the integration boundary.
crates/trusted-server-core/src/integrations/permutive.rs	Use Fastly compat shims for custom-header forwarding at the integration boundary.
crates/trusted-server-core/src/integrations/prebid.rs	Bridge request-info construction and cookie forwarding through compat conversions.
crates/trusted-server-core/src/integrations/registry.rs	Use compat conversions for synthetic ID generation and synthetic cookie response handling.
crates/trusted-server-core/src/integrations/testlight.rs	Bridge the migrated synthetic ID lookup into the Fastly integration path.
crates/trusted-server-core/src/lib.rs	Export the compat module and add migration guard tests.
crates/trusted-server-core/src/migration_guards.rs	Add a regression test preventing migrated utility modules from reintroducing direct Fastly request/response types.
crates/trusted-server-core/src/proxy.rs	Bridge proxy synthetic ID reads through the migrated HTTP utility layer.
crates/trusted-server-core/src/publisher.rs	Route TSJS serving, request-info extraction, consent handling, and synthetic cookie writes through compat conversions.
crates/trusted-server-core/src/request_signing/endpoints.rs	Switch JSON content-type constants to mime::APPLICATION_JSON.
crates/trusted-server-core/src/synthetic.rs	Migrate synthetic ID helpers and tests to http::Request<EdgeBody>.

Closes

Closes #492

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
• 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: focused Rust verification with cargo test --package trusted-server-core compat -- --nocapture, cargo test --package trusted-server-core http_util -- --nocapture, cargo test --package trusted-server-core request_signing -- --nocapture, and cargo test --package trusted-server-core migration_guards -- --nocapture
• Other: local cd crates/js/lib && npx vitest run currently fails before test execution with ERR_REQUIRE_ESM in html-encoding-sniffer -> @exodus/bytes/encoding-lite.js; leaving CI to capture the current JS environment issue.

Hardening note

This PR does not add any new config-derived regex or pattern compilation paths. Basic auth still surfaces invalid enabled handler regex configuration as an error rather than panicking, covered by auth::tests::returns_error_for_invalid_handler_regex_without_panicking alongside the existing settings startup validation tests.

Checklist

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

[ChristianPavilonis]

Summary

This PR cleanly migrates utility-layer functions (auth, cookies, synthetic, http_util, consent/extraction, consent/mod) from fastly::Request/fastly::Response to http::Request/http::Response with EdgeBody. The compat bridge pattern is sound and well-tested.

Two duplicate-header-dropping bugs need fixing before merge — see inline comments.

Blocking

🔧 wrench

• to_fastly_request drops duplicate headers: Uses set_header instead of append_header, losing multi-valued headers during conversion (compat.rs:65)
• copy_custom_headers drops duplicate X-headers: Uses insert instead of append, a behavioral regression from the old Fastly-based version (http_util.rs:22)

Non-blocking

🤔 thinking

• Migration guard strip_line_comments is naive about string literals: A Rust string literal like "fastly::Request" in a test assertion would trigger a false positive. Currently does not happen, but the approach is fragile. Consider adding a brief comment documenting the limitation. (migration_guards.rs)

🌱 seedling

• copy_custom_headers in http_util.rs has no callers outside tests: The integrations (lockr, permutive) now call compat::copy_fastly_custom_headers instead. Worth noting for PR 15 cleanup.

⛏ nitpick

• Dead "X-" check in copy_fastly_custom_headers: The check for name_str.starts_with("X-") in compat.rs:144 is dead code since Fastly normalizes header names to lowercase. The migrated copy_custom_headers in http_util.rs only checks "x-". Not a correctness issue, but the asymmetry may confuse readers.
• Temporary compat functions well-documented with removal targets: Every public function in compat.rs has a # PR 15 removal target annotation — great practice for tracking temporary code.

👍 praise

• Thorough compat test coverage: 11 focused tests covering round-trip conversions, duplicate header preservation, header sanitization, cookie forwarding with consent stripping, and synthetic cookie lifecycle. Excellent scaffolding for temporary bridge code.
• Migration guard test is a clever regression barrier: The include_str! approach to scan source files for banned Fastly types provides a compile-time-like guarantee without proc macros.

📝 note

• mime dependency is appropriate: Replaces fastly::mime::APPLICATION_JSON references. Well-maintained, zero-dependency crate suitable for the use case.

CI Status

• All checks: PASS

[aram356]

Summary

Migrates the utility layer (auth, cookies, synthetic, http_util, consent) off direct fastly::Request/fastly::Response to http::{Request, Response}<EdgeBody> with a temporary compat bridge. Well-structured migration with good test coverage and clear lifecycle annotations. Two header-handling bugs need fixing before merge.

Blocking

🔧 wrench

• copy_custom_headers drops duplicate headers: uses insert instead of append in http_util.rs:22. The compat shim preserves duplicates; this migrated version doesn't. Will become a production regression when the compat layer is removed in PR 15.
• to_fastly_request drops duplicate headers: uses set_header instead of append_header in compat.rs:65. Inconsistent with to_fastly_response which correctly uses append_header on line 109.

Non-blocking

🤔 thinking

• Migration guard doesn't handle block comments: strip_line_comments in migration_guards.rs only strips // line comments. A /* fastly::Request */ block comment would cause a false positive, and a real regression hidden inside a block comment wouldn't be caught. Acceptable for a guard test (false positives are safe), just noting the limitation.

🌱 seedling

• Add a to_fastly_request duplicate-header round-trip test: after fixing the append_header issue, a round-trip test (http::Request → fastly::Request → http::Request) verifying duplicate header preservation would prevent future regressions.

⛏ nitpick

• Redundant case check in copy_fastly_custom_headers: compat.rs:144 checks both "x-" and "X-" but Fastly's HeaderName is already case-normalized to lowercase. Not worth changing in temporary code.

CI Status

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

[aram356]

Summary

Prior blocking findings (duplicate-header drops in to_fastly_request and copy_custom_headers) are both fixed in 2817761, with round-trip regression tests added. CI is green. Approving; non-blocking observations below.

Non-blocking

🤔 thinking

• from_fastly_request_ref silently drops body (crates/trusted-server-core/src/compat.rs:54): docs note the body is empty, but the name doesn't signal it. Footgun if a future caller passes a POST expecting body access. Consider renaming to from_fastly_headers_ref or adding a debug_assert! when the source request has a non-empty body. All current callers only read headers, so not a bug today.
• Double conversion on the auction hot path: auction/endpoints.rs:50 builds http_req once, but auction/formats.rs:93 (convert_tsjs_to_auction_request) re-converts the same underlying fastly::Request again via from_fastly_request_ref. Each conversion iterates all headers — two copies per auction request. Acceptable for a temporary bridge (PR 15 removes it), but worth a comment referencing PR 15 so the duplication doesn't get frozen.
• forward_cookie_header uses insert, not append (crates/trusted-server-core/src/cookies.rs:167,175,184): fine for HTTP/1 where Cookie is a single semicolon-joined value, but HTTP/2 (RFC 7540 §8.1.2.5) allows splitting across multiple headers and only the first would be forwarded. Matches pre-migration behavior and Fastly concatenates HTTP/2 cookie headers upstream, so likely not a live bug — worth documenting the assumption.

🌱 seedling

• Migration guard scope is "utility modules only" (crates/trusted-server-core/src/migration_guards.rs:27-37): guards 6 files. Handler/integration files (publisher.rs, proxy.rs, registry.rs, integrations/*.rs, auction/*.rs) still use fastly::Request by design. PR 12–14 should extend the banned-patterns list as files are migrated.

⛏ nitpick

• Dead case check in copy_fastly_custom_headers (crates/trusted-server-core/src/compat.rs:144): checks both "x-" and "X-" though fastly::Request normalizes to lowercase. Not worth a commit in temporary code — trim on the next touch.

CI Status

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