[jwrosewell]

Summary

• Move the Flight rewriter into the Next.js module.
• Row 40 of the stack listed in the pluggable modules issue (Pluggable, competition-neutral modules with a technical permission model #777), on feature/39-source-modules. The fork's pull request The Flight rewriter is a middleware of the Next.js module jwrosewell/trusted-server#35 carries the same commits.

Changes

Area	Change
crates/framework/nextjs	3 files, 696 lines added, 0 removed
crates/trusted-server-core/src	8 files, 309 lines added, 487 removed
docs/superpowers	1 file, 109 lines added, 0 removed
docs/guide	3 files, 37 lines added, 18 removed
crates/trusted-server-modules/src	1 file, 12 lines added, 2 removed
trusted-server.example.toml	1 file, 11 lines added, 2 removed
CHANGELOG.md	1 file, 3 lines added, 1 removed
crates/trusted-server-core/README.md	1 file, 2 lines added, 3 removed

Closes

Closes #1340

Spec

Spec: rsc-flight-middleware

Test plan

CI on this pull request at 61de267 passed all 29 checks.

• cargo test-fastly && cargo test-axum
• cargo clippy-fastly && cargo clippy-axum
• cargo fmt --all -- --check
• JS tests: cd crates/trusted-server-js/lib && npx vitest run
• JS format: cd crates/trusted-server-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: the full workflow set of this repository, run on this pull request at 61de267

Checklist

• Changes follow AGENTS.md conventions
• No unwrap() in production code (clippy denies unwrap_used in CI)
• Uses log macros as AGENTS.md asks (not println!)
• New code has tests
• No secrets or credentials committed

---

On top of the source module series (#1380). Issue: #1340.

What this adds

What changes.

The React Server Components Flight rewriter leaves core for the Next.js module. crates/trusted-server-core/src/rsc_flight.rs is now crates/framework/nextjs/src/flight.rs, the fetch middleware framework.nextjs.flight for the media type text/x-component, registered beside framework.nextjs whenever [framework] module = "nextjs" selects the module and run where a [[fetch]] entry names it for that media type.

[[fetch]]
media_type = "text/x-component"
middleware = ["framework.nextjs.flight"]

How it works.

• Core knows nothing of Flight. The publisher path's two Flight branches are gone, core's media type dispatch no longer excludes text/x-component, and the rewriter's five tests moved with it.
• A middleware may say it moves the origin address. Core's text pass runs its own origin address replacer ahead of every non-HTML middleware, which would break a Flight row's length prefix before the rewriter saw it. A middleware that rewrites addresses itself says so through Middleware::moves_origin_address, false by default, and the publisher's text pass leaves that media type to it, whether or not an entry names the middleware, so a Flight response without an entry passes through as the origin sent it.
• The address comes from the host. The middleware builds https://host and http://host from the origin host it is given, as the module's HTML rewriting does, so an origin whose address has a folder keeps that folder in a rewritten address.
• A charset other than UTF-8 passes through. The text pass runs nothing on it and core's replacer is skipped, where the previous rewriter ran regardless.

Why

Every framework's code leaves core, and the stack gave a middleware a media type so that a change to a text response has a place. This was the last page change that predated it.

What breaks

A deployment that fronts a Next.js site names the rewriter in a [[fetch]] entry for text/x-component, as the guide shows. Without the module selected, a Flight response takes core's plain text handling, where core used to rewrite Flight for everyone. trusted_server_core::rsc_flight is gone.

The commits

1. The Flight rewriter is a middleware of the Next.js module.
2. A merge of the series below, which carries the fixes made lower in the stack.
3. A merge of the series below, which carries the page origin change.
4. The Flight middleware design states how it differs from core's replacement and its rollout, and takes its round 2 corrections.
5. Later merges of the series below carry Tech Lab main at 6ef07ae.