[rqbazan]

Summary

@rrlab/tsdown-config's default lib preset sets dts: true. tsdown takes typescript only as an optional peer, and rr plugins add tsdown didn't install it, so rr pack failed in any project without the ts or astro plugin.

 install(ctx)  // @rrlab/tsdown-plugin
   devDependencies
     tsdown ^0.22.0
+    typescript ^6.0.0   // unless dependencies/devDependencies already have it
     @rrlab/tsdown-config
 uninstall(ctx)
   remove tsdown, @rrlab/tsdown-config   // typescript stays: the host or ts/astro may use it

• ^6.0.0 is the same pin as the ts and astro plugins, so the order of rr plugins add ts and rr plugins add tsdown doesn't matter.
• A host that already installs typescript keeps its range: pnpm add would otherwise rewrite it. A peer-only declaration doesn't count, because it isn't installed.
• New optional peer typescript >=5.0.0: the bin preset builds without it.

Evidence

Non-TTY e2e in a temp project, with the worktree's packed @rrlab/cli and @rrlab/tsdown-plugin (via pnpm.overrides) and rr plugins add oxc, so the ts plugin isn't installed:

• Before (npm 1.2.1): rr plugins add tsdown </dev/null adds no typescript. rr pack exits 1 with Error: TypeScript is not installed. You should install typescript package.
  After: typescript ^6.0.3 is added. rr pack exits 0 and writes dist/index.d.mts, and rr check passes.
• Host on typescript ~5.9: left as ~5.9.3. Host with typescript only as a peer: installed. ts then tsdown, and tsdown then ts, both end with one typescript and green rr pack/rr tsc. rr plugins remove tsdown --yes leaves typescript.
• install.test.ts: with the index.ts fix reverted, 5 tests fail, covering the create, skip, decline, user-skip and peer-only paths. With the fix, 25/25 pass.

Merge Danger

Door: two-way

Blast Radius: small

Only rr plugins add tsdown changes: it adds one dev dependency when it's missing. Existing projects aren't touched until they re-run the add.

🤖 Generated with Claude Code

https://claude.ai/code/session_01EZVC7xzzsEmByszmfff4u2

[changeset-bot]

🦋 Changeset detected

Latest commit: 8ae3af4

The changes in this PR will be included in the next version bump.

This PR includes changesets to release 1 package

Name	Type
@rrlab/tsdown-plugin	Patch

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[vland-bot]

Preview release

Latest commit: 8ae3af4

Some packages have been released:

Package	Version	Install
@rrlab/tsdown-plugin	1.2.2-git-8ae3af4.0	@rrlab/tsdown-plugin@1.2.2-git-8ae3af4.0

Note

Use the PR number as tag to install any package. For instance:

pnpm add @rrlab/tsdown-plugin@pr-283