fix(astro): register middleware by package subpath, not chunk-relative URL

[tenphi]

Problem

tastyIntegration() is broken in the published 3.0.0 and fails the build outright for every Astro consumer.

It registered its middleware with:

addMiddleware({ entrypoint: new URL('./astro-middleware.js', import.meta.url), order: 'pre' })

import.meta.url points at the emitted chunk, not the source file. The v3 build hoists tastyIntegration out of dist/ssr/astro.js into a shared chunk at the dist/ root (dist/astro-B53trJyX.js), one directory up — so the URL resolved to dist/astro-middleware.js, which doesn't exist. The real file shipped fine at dist/ssr/astro-middleware.js.

Reported downstream; the reporter worked around it with the documented manual-middleware path (src/middleware.ts calling tastyMiddleware({ transferCache: false }), integration dropped from astro.config.ts).

Second bug found while fixing this

tastyIntegration({ islands: false }) silently kept emitting the class-list transfer script — so the "ships zero client JS" promise in the docs did not hold.

The flag travelled through module-level state in astro-transfer-cache.ts: written by the integration when the Astro config is loaded, read by the middleware at request time. Those are different module instances, and for built output different processes entirely, so the middleware always saw the true default. This means the reporter's manual workaround was in fact more correct than the integration it replaced, not merely equivalent.

Fix

• Entrypoint is now a package subpath (@tenphi/tasty/ssr/astro-middleware), resolved through the exports map. Immune to chunk layout, which is free to change at any time.
• Two self-contained entrypoints instead of shared mutable state, since addMiddleware() cannot pass options. astro-middleware bakes in transferCache: true, astro-middleware-static bakes in false. astro-transfer-cache.ts is deleted.
• New exports ./ssr/astro-middleware and ./ssr/astro-middleware-static exist only so Astro can resolve them by specifier; manual setups should keep using tastyMiddleware(). Documented as such in docs/ssr.md and AGENTS.md.

Consumers on the manual workaround can revert to tastyIntegration() once on this release, or keep the manual setup — both are supported.

Tests

New src/ssr/astro-integration.test.ts. The important one asserts the entrypoint is actually reachable — declared in package.json exports and produced by a tsdown entry — rather than just that some string was passed, which is the class of bug that shipped. Both guards were verified to fail against the broken code before being committed:

• reinstating the new URL(...) entrypoint → 4 tests fail
• removing the exports entry → @tenphi/tasty/ssr/astro-middleware is not declared in package.json "exports"

The transfer-cache tests render through each onRequest with a collected style chunk and assert the islands variant emits window.__TASTY__ while the static one emits no <script> at all.

Verification

• pnpm test — 66 files, 1939 passed
• pnpm hygiene (lint + format + typecheck), pnpm knip, pnpm size — all clean
• Public API snapshot updated: adds exactly the two new subpaths, each exporting onRequest
• End-to-end against the real artifact: npm pack, installed the tarball into a clean consumer, ran the integration hook and dynamically imported whatever entrypoint it handed back — resolves and loads for both islands: true and islands: false

🤖 Generated with Claude Code

[github-actions]

📦 Snapshot release

Published 0.0.0-snapshot.2394160.

pnpm add @tenphi/tasty@0.0.0-snapshot.2394160