[sajonaro]

Why

Without writ-lsp the extension only highlights syntax. The one fix it offered was an opam pin typed into a terminal, which needs an OCaml toolchain and minutes of building just to get an editor working. writ already publishes a release tarball for each Linux architecture, with a checksum beside it. That tarball holds everything the extension needs: writ-lsp, the writ CLI the verbs run, and the standard library where the resolver looks for it.

What

A Download writ button appears in three places:

• the Writ panel
• the "no language server" error message
• the Command Palette, as Writ: Download writ

Clicking it does this:

1. Picks a release. It takes the release tagged with this extension's version. If that version was never released, it falls back to the latest release, and the panel's version verdict reports the difference.
2. Downloads and verifies it. It fetches the tarball for this platform and checks its .sha256. On a mismatch the download is deleted, not unpacked.
3. Installs it privately. It unpacks into the extension's global storage, renaming into place in one step so an interrupted download never counts as an install. Nothing goes on PATH, and uninstalling the extension removes it.
4. Starts it. The client restarts through the same reload a changed setting uses, now one function in extension.js.

A hand-installed writ always wins. A download is the last place the extension looks, after PATH. For the same reason, the panel offers the button only when there's no server at all, or when the server in use is itself a download. Anywhere else the download would never run, so those cases get the opam option instead.

macOS and Windows have no release tarball yet, so they are pointed to opam.

Verified

• New tests: test/download.test.js adds 25 offline checks for tarball names, checksum parsing, what counts as an install and in what order, search-order placement, and when the panel offers the button. Putting a download ahead of PATH on purpose makes two of them fail.
• Live download: with WRIT_DOWNLOAD_LIVE=1, the test downloads the real v0.2.0 release and runs it. All 28 checks succeed.
• Command wiring: a script stubs the VS Code API and calls the real command. The progress messages appear, the extension reloads, and the resolver switches to the downloaded server and its CLI.
• Downstream CI: writ's downstream workflow ran on this branch, and every suite succeeded. The extension's six test files there report 25, 23, 49, 21, 30 and 8 checks.
• Not done: I haven't clicked the button inside a running VS Code. That needs a manual check before merging.

Worth knowing

• Version mismatch on first download. The extension is 0.1.0 and writ's only release is v0.2.0, so today the download takes 0.2.0 and the panel shows a mismatch. Running scripts/version.sh --from-writ before the next extension release makes the two match exactly.

🤖 Generated with Claude Code