update-svelte

name	update-svelte
description	Bump the pinned Svelte version across the whole repo — pin, vendored `original/`, docs, README, playground import map — then regenerate expected outputs and run the checks. Manual launch only via `/update-svelte`.
argument-hint	[version, e.g. 5.56.0]
allowed-tools	Bash, Read, Edit, Grep
disable-model-invocation	true

update-svelte

The Svelte version is pinned across the repo and must move as one. Sites are of three kinds:

• pin/prose — package.json, package-lock.json, README.md: text occurrences of the version.
• vendored mirror — original/: a byte-for-byte copy of node_modules/svelte (source of truth for parity). original/compiler/ = node_modules/svelte/src/compiler/, original/package.json = node_modules/svelte/package.json, original/docs/ = documentation/docs/ from the GitHub monorepo.
• playground import map — playground/index.html: a JSPM-generated dependency graph the browser loads straight from the CDN. Independent of node_modules — its own pin.

Every other consumer reads Svelte from node_modules, driven by the single pin in package.json — no separate steps.

Done when the OLD version appears nowhere unintended, original/ diffs clean against node_modules/svelte, the playground resolves svelte@NEW, and just test-compiler, just test-diagnostics, just lint are all green.

Work from the repo root.

Task boundary

This skill does not fix new parity divergences the newer Svelte introduces: in step 9 those surface as just test-compiler failures. That is separate compiler work, not hand-editing of expected files — list such failures in the report; do not paper over them.

Steps

1. Fix OLD and NEW

• OLD — the current "svelte" value in package.json.
• NEW — the invocation argument. If absent, ask the user; npm view svelte version gives latest for reference.

Criterion: both versions known and OLD ≠ NEW.

2. Move the pin and install

• In package.json replace "svelte": "OLD" → "svelte": "NEW" (dependencies section, exact pin, no caret).
• npm install — updates package-lock.json and pulls the new node_modules/svelte.

Criterion: node -p "require('svelte/package.json').version" prints NEW.

3. Re-vendor original/ from the installed package

rsync -a --delete node_modules/svelte/src/compiler/ original/compiler/
cp node_modules/svelte/package.json original/package.json

Criterion (both diffs empty):

diff -rq original/compiler node_modules/svelte/src/compiler
diff -q  original/package.json node_modules/svelte/package.json

4. Re-vendor original/docs/ from the GitHub tag

The npm tarball has no docs — pull them from the monorepo at tag svelte@NEW.

TMP="$(mktemp -d)"
curl -fsSL "https://github.com/sveltejs/svelte/archive/refs/tags/[e-mail]" | tar xz -C "$TMP"
SRC="$(find "$TMP" -type d -path '*/documentation/docs' | head -1)"
[ -n "$SRC" ] || { echo "docs for svelte@NEW not found — check the tag; skip"; exit 1; }
rsync -a --delete "$SRC/" original/docs/

The [ -n "$SRC" ] guard is load-bearing: an empty SRC turns the next line into rsync --delete "/" …, mirroring the filesystem root.

Criterion: original/docs/index.md exists and git status original/docs/ shows the refresh. If the URL 404s, check the tag name at github.com/sveltejs/svelte/tags and retry; if the network is unavailable, report and continue.

5. Update prose

In README.md replace every OLD → NEW.

Criterion: grep -c OLD README.md → 0.

6. Regenerate the playground import map

playground/index.html loads the reference compiler from the JSPM CDN, so its scopes block pins svelte's transitive deps too — hand-swapping the version alone can leave them stale. Regenerate the map for svelte@NEW with the JSPM generator:

npm i --no-save @jspm/generator
node --input-type=module -e '
  import { Generator } from "@jspm/generator";
  const g = new Generator({ defaultProvider: "jspm.io", env: ["browser","module","production"] });
  await g.install("svelte@NEW/compiler");
  console.log(JSON.stringify(g.getMap(), null, 2));
'

From the output, replace in playground/index.html:

• imports["svelte/compiler"] — the new CDN URL,
• the whole scopes["https://ga.jspm.io/"] block.

Then set the UI label — the drawer-subtitle line reading svelte/compiler · v… — to svelte/compiler · vNEW.

If the generator is unavailable, fall back to the online generator at generator.jspm.io (provider jspm.io, env browser/module/production, install svelte@NEW/compiler).

Criteria:

• grep -c 'svelte@OLD' playground/index.html → 0
• curl -fsI "https://ga.jspm.io/npm:svelte@NEW/src/compiler/index.js" → 200
• (manual) just playground, open it — the svelte side compiles a sample and the label reads vNEW.

7. Sweep: no OLD version left

grep -rn 'OLD' . --exclude-dir=node_modules --exclude-dir=.git --exclude-dir=target

Criterion: output empty, or only clearly-historical occurrences (changelog and the like). Any pin/vendored/prose/import-map hit of OLD means a missed site — go back and fix it.

8. Regenerate expected outputs

just generate — rewrites every case-svelte.js from the new svelte/compiler. A large diff here is expected: it is the new reference output.

Criterion: the command finishes without errors.

9. Verify green

Run in order: just test-compiler, just test-diagnostics, just lint.

Criterion: all three green. For test-compiler, apply the Task boundary above: new failures are parity work to report, not expected files to hand-edit.