fix(pack): harden tsdown extension wiring and lightningcss version sync

- wireBundledTsdownExtensions: scan every emitted chunk (not just
  build-*.js) and assert the bundled ./tsdown-css.js is referenced, so a
  rolldown chunking change can't silently ship an unrewritten import.
- upgrade-deps: match any lightningcss range value so a non-caret range
  from @tsdown/css can't poison the next run's pattern.
- rfc: lightningcss is a core dependency, not an optional peer.

Author: fengmk2

.github/scripts/upgrade-deps.ts

@@ -252,7 +252,9 @@ async function updatePnpmWorkspace(versions: PnpmWorkspaceVersions): Promise<voi
     // tsdown upgrade that bumps lightningcss is mirrored here.
     {
       name: 'lightningcss',
-      pattern: /\n {2}lightningcss: (\^?[\d.]+(?:-[\w.]+)?)\n/,
+      // Match any range value (not just `^x.y.z`) so the pattern can re-match
+      // whatever `@tsdown/css` declares (`~`, `>=`, compound ranges) on the next run.
+      pattern: /\n {2}lightningcss: ([^\n]+)\n/,
       replacement: `\n  lightningcss: ${versions.lightningcss}\n`,
       newVersion: versions.lightningcss,
     },

packages/core/build.ts

@@ -588,9 +588,11 @@ async function brandTsdown() {
 // top-level packages. See https://github.com/voidzero-dev/vite-plus/issues/1586
 async function wireBundledTsdownExtensions() {
   const tsdownDistDir = join(projectDir, 'dist/tsdown');
-  const buildFiles = await glob(toPosixPath(join(tsdownDistDir, 'build-*.js')), { absolute: true });
-  if (buildFiles.length === 0) {
-    throw new Error('wireBundledTsdownExtensions: no build chunk found in dist/tsdown/');
+  // Scan every emitted chunk, not just `build-*.js`: which chunk rolldown hoists
+  // these call sites into depends on its chunking heuristics, so don't pin to one.
+  const chunkFiles = await glob(toPosixPath(join(tsdownDistDir, '*.js')), { absolute: true });
+  if (chunkFiles.length === 0) {
+    throw new Error('wireBundledTsdownExtensions: no chunk found in dist/tsdown/');
   }
 
   // Route `@tsdown/exe` and `@tsdown/css` to the bundled entries.
@@ -602,8 +604,12 @@ async function wireBundledTsdownExtensions() {
   // bundled), which resolves to core's own `lightningcss` dependency.
   let exeWired = false;
   let cssWired = false;
-  for (const buildFile of buildFiles) {
-    let content = await readFile(buildFile, 'utf-8');
+  // The `import("@tsdown/css")` call site may already be deduped to the bundled
+  // entry by rolldown; track whether the bundled load ends up referenced either
+  // way so a silent miss (no rewrite and no dedup) fails the build.
+  let cssLoadWired = false;
+  for (const chunkFile of chunkFiles) {
+    let content = await readFile(chunkFile, 'utf-8');
     let changed = false;
     if (content.includes('importWithError("@tsdown/exe")')) {
       content = content.replaceAll('importWithError("@tsdown/exe")', 'import("./tsdown-exe.js")');
@@ -619,8 +625,11 @@ async function wireBundledTsdownExtensions() {
       content = content.replaceAll('import("@tsdown/css")', 'import("./tsdown-css.js")');
       changed = true;
     }
+    if (content.includes('import("./tsdown-css.js")')) {
+      cssLoadWired = true;
+    }
     if (changed) {
-      await writeFile(buildFile, content);
+      await writeFile(chunkFile, content);
     }
   }
   if (!exeWired) {
@@ -629,6 +638,9 @@ async function wireBundledTsdownExtensions() {
   if (!cssWired) {
     throw new Error('wireBundledTsdownExtensions: `pkgExists("@tsdown/css")` not found');
   }
+  if (!cssLoadWired) {
+    throw new Error('wireBundledTsdownExtensions: bundled `./tsdown-css.js` is never imported');
+  }
 }
 
 // Actually do nothing now, we will polish it in the future when `vitepress` is ready

rfcs/pack-command.md

@@ -300,7 +300,7 @@ These are distinct commands:
 - Ensures consistent tsdown version across all vite-plus users
 - Avoids version conflicts in monorepos
 - The core build process bundles JS, CJS deps, and types together
-- The extensions peer-depend on `tsdown`/`tsdown/internal`, which Vite+ does not expose as a top-level package, so bundling them is the only way they resolve (issue #1586). Only `lightningcss` (native) stays external as an optional peer.
+- The extensions peer-depend on `tsdown`/`tsdown/internal`, which Vite+ does not expose as a top-level package, so bundling them is the only way they resolve (issue #1586). Only `lightningcss` (native, cannot be bundled) stays external; it ships as a regular core dependency.
 
 ### 4. Category C Delegation
 
@@ -404,7 +404,7 @@ This RFC documents an existing command with no breaking changes:
 - All existing `vp pack` options continue to work
 - The new `--exe` flag is purely additive
 - Config format in `vite.config.ts` is unchanged
-- Bundling `@tsdown/exe`/`@tsdown/css` is a strict improvement: projects that previously installed them keep working and no longer need to. CSS bundling now only requires the optional `lightningcss` peer (`vp add -D lightningcss`), which is loaded lazily with an actionable error when missing.
+- Bundling `@tsdown/exe`/`@tsdown/css` is a strict improvement: projects that previously installed them keep working and no longer need to. CSS bundling works out of the box, `lightningcss` is a core dependency that ships with the toolchain, so nothing extra needs installing.
 
 ## Exe Advanced Configuration