Improve API reference navigation and changelog

.changeset/README.md

@@ -1,3 +1,35 @@
 # Changesets
 
 Run `pnpm changeset` for every user-facing change.
+
+## Writing changelog entries
+
+Changeset descriptions are published directly on the documentation website. Write them for library users rather than repository maintainers.
+
+- Lead with the user-visible outcome and name the affected API when useful.
+- Keep the entry short and specific. One to three brief paragraphs is usually enough.
+- Use separate paragraphs when they make the outcome, motivation, or migration clearer.
+- Use inline code for API names, types, and short expressions.
+- Include at most one small fenced TypeScript example when an API is added or its usage changes meaningfully.
+- For a breaking change, state what changed and show the replacement or migration directly.
+- Omit commit hashes, pull request numbers, implementation history, test details, and internal refactoring unless they affect users.
+
+A typical API entry looks like:
+
+````md
+Add `Machine.example` for describing the user-visible behavior.
+
+Use it when a short explanation would not make the new calling pattern clear:
+
+```ts
+const value = Machine.example(input)
+```
+````
+
+Prefer a shorter entry without an example for fixes and internal improvements:
+
+```md
+Fix resumed machines so nested history is restored before raised events are processed.
+
+This preserves the same observable transition order as a freshly started machine.
+```

.github/workflows/ci.yml

@@ -62,6 +62,7 @@ jobs:
 
   example:
     needs: discover-examples
+    if: needs.discover-examples.outputs.required == 'true'
     strategy:
       fail-fast: false
       matrix:

.github/workflows/website.yml

@@ -22,6 +22,8 @@ jobs:
       pages: read
     steps:
       - uses: actions/checkout@v7
+        with:
+          fetch-depth: 0
       - uses: pnpm/action-setup@v6
       - uses: actions/setup-node@v7
         with:

AGENTS.md

@@ -49,5 +49,5 @@ Every package directly below `examples/` must have a `check` script and a commit
 
 ## Pull request conventions
 
-- Add or update a changeset for changes under `src/` or changes to `package.json`.
+- Add or update a changeset for changes under `src/` or changes to `package.json`, following the changelog-writing guide in `.changeset/README.md`.
 - Fill in the pull request template, including the validation performed and the changeset decision.

CHANGELOG.md

@@ -4,9 +4,31 @@
 
 ### Minor Changes
 
-- b192484: Allow state query helpers to inspect extracted snapshot subtrees, and add
-  equality-aware `AtomMachine.selectSnapshot` and `selectSnapshotChild`
-  combinators.
+- b192484: Allow `Machine.defineStates` query helpers to inspect an extracted
+  snapshot subtree. Paths remain absolute and type-safe, but `get`,
+  `getSnapshot`, and `matches` can now continue from a snapshot selected
+  earlier instead of requiring the complete root snapshot.
+
+  ```ts
+  const readySnapshot = States.getSnapshot(snapshot, "Ready")
+
+  if (Option.isSome(readySnapshot)) {
+    States.get(readySnapshot.value, "Ready.editor")
+    States.matches(readySnapshot.value, "Ready.editor.Editing")
+  }
+
+  const editorSnapshotAtom = AtomMachine.selectSnapshot(
+    machineAtom,
+    "Ready.editor"
+  )
+  ```
+
+  Add equality-aware `AtomMachine.selectSnapshot` and
+  `AtomMachine.selectSnapshotChild` combinators for reactive consumers that
+  need the complete logical snapshot subtree instead of only its state value.
+  The selected atoms retain nested topology, suppress structurally equal
+  updates, and produce `Option.none()` while the path or invoked child is
+  inactive.
 
 ## 0.6.1
 

scripts/api-reference-site/api-reference-site.test.mjs

@@ -7,9 +7,13 @@ import {
   normalizeBasePath,
   normalizeGitHubStars,
   normalizeOrigin,
+  parseChangelog,
+  parseChangeset,
+  renderChangelogPage,
   renderIndexPage,
   renderLayout,
   renderMarkdown,
+  renderModulePage,
   renderRobots,
   renderSitemap,
   siteManifest,
@@ -30,6 +34,22 @@ test("renders documentation prose while escaping source HTML", () => {
   assert.doesNotMatch(renderMarkdown("<script>alert(1)</script>"), /<script>/)
 })
 
+test("renders fenced code with highlighting and copy controls", () => {
+  const html = renderMarkdown(`Call the new API:
+
+\`\`\`ts
+const value = Machine.example("safe")
+\`\`\`
+
+Then reuse \`value\`.`)
+  assert.match(html, /<p>Call the new API:<\/p>/)
+  assert.match(html, /class="code-block code-block--markdown"/)
+  assert.match(html, /aria-label="Copy ts code"/)
+  assert.match(html, /syntax-keyword">const<\/span>/)
+  assert.match(html, /syntax-string">&quot;safe&quot;<\/span>/)
+  assert.match(html, /<p>Then reuse <code>value<\/code>\.<\/p>/)
+})
+
 test("assigns deterministic unique anchors to duplicate declarations", () => {
   const first = { name: "Machine" }
   const second = { name: "Machine" }
@@ -88,6 +108,92 @@ const site = {
   title: "Effect Machine"
 }
 
+test("parses Changesets release entries and pending descriptions", () => {
+  const releases = parseChangelog(`# Package
+
+## 1.2.0
+
+### Minor Changes
+
+- abc1234: Add a typed \`make\` helper.
+
+  Preserve inference across multiple lines.
+
+  \`\`\`ts
+  const machine = make()
+  \`\`\`
+
+### Patch Changes
+
+- def5678: Fix escaped output.
+`, new Map([["1.2.0", "2026-08-13"]]))
+  assert.deepEqual(releases, [{
+    version: "1.2.0",
+    date: "2026-08-13",
+    groups: [{
+      type: "minor",
+      entries: [{
+        description: "Add a typed `make` helper.\n\nPreserve inference across multiple lines.\n\n```ts\nconst machine = make()\n```"
+      }]
+    }, {
+      type: "patch",
+      entries: [{ description: "Fix escaped output." }]
+    }]
+  }])
+  assert.deepEqual(parseChangeset(`---
+"@typeonce/effect-machine": minor
+---
+
+Add snapshot selectors.
+`, "@typeonce/effect-machine"), { type: "minor", description: "Add snapshot selectors." })
+  assert.equal(parseChangeset(`---
+"another-package": patch
+---
+
+Ignore this package.
+`, "@typeonce/effect-machine"), undefined)
+})
+
+test("renders a navigable changelog with release dates", () => {
+  const html = renderChangelogPage({
+    ...site,
+    changelog: [{
+      version: "1.2.0",
+      date: "2026-08-13",
+      groups: [{ type: "minor", entries: [{ description: "Add a feature." }] }]
+    }]
+  })
+  assert.match(html, /class="navigation-changelog is-current"/)
+  assert.match(html, /id="release-1-2-0">v1\.2\.0/)
+  assert.match(html, /datetime="2026-08-13">August 13, 2026/)
+  assert.match(html, /<li><p>Add a feature\.<\/p><\/li>/)
+})
+
+test("renders collapsible category navigation with declaration anchors", () => {
+  const declaration = {
+    name: "make",
+    kind: "variable",
+    description: "Creates a machine.",
+    examples: [],
+    see: []
+  }
+  const module = {
+    api: {
+      declarationCount: 1,
+      description: "State machine APIs",
+      groups: [{ category: "constructors", declarations: [declaration] }]
+    },
+    export: "./Machine",
+    label: "Machine",
+    route: "Machine"
+  }
+  const html = renderModulePage({ ...site, modules: [module] }, module)
+  assert.match(html, /<details class="page-toc__group">/)
+  assert.match(html, /<summary>[\s\S]*Constructors[\s\S]*<\/summary>/)
+  assert.match(html, /<a href="#make">make<\/a>/)
+  assert.match(html, /<h3 id="make">make<\/h3>/)
+})
+
 test("renders canonical and social metadata without exposing the internal channel", () => {
   const html = renderLayout(site, {
     content: '<section class="reference-hero"><div class="eyebrow">API reference</div></section>',
@@ -162,6 +268,7 @@ test("generates manifest, robots, and sitemap URLs from the deployment base", ()
   assert.equal(manifest.icons[2].purpose, "maskable")
   assert.match(renderRobots(site), /Sitemap: https:\/\/docs\.example\.com\/docs\/sitemap\.xml/)
   assert.match(renderSitemap(site), /<loc>https:\/\/docs\.example\.com\/docs\/Machine\/<\/loc>/)
+  assert.match(renderSitemap(site), /<loc>https:\/\/docs\.example\.com\/docs\/changelog\/<\/loc>/)
 })
 
 test("accepts only pathless HTTPS production origins", () => {

scripts/api-reference-site/assets/client.js

@@ -85,14 +85,26 @@ searchInput?.addEventListener("input", async () => {
     const search = await pagefind.search(query)
     const data = await Promise.all(search.results.slice(0, 12).map((result) => result.data()))
     if (sequence !== searchSequence) return
-    searchStatus.textContent = `${search.results.length} result${search.results.length === 1 ? "" : "s"}`
-    for (const result of data) {
+    const seen = new Set()
+    const results = data.flatMap((result) => {
+      const sections = result.sub_results?.filter((section) => section.url.includes("#")) ?? []
+      const candidates = sections.length === 0
+        ? [{ title: result.meta.title, url: result.url, excerpt: result.excerpt }]
+        : sections.map((section) => ({ ...section, title: `${section.title} · ${result.meta.title}` }))
+      return candidates.filter((candidate) => {
+        if (seen.has(candidate.url)) return false
+        seen.add(candidate.url)
+        return true
+      })
+    }).slice(0, 12)
+    searchStatus.textContent = `${results.length} result${results.length === 1 ? "" : "s"}`
+    for (const result of results) {
       const item = document.createElement("li")
       const link = document.createElement("a")
       const title = document.createElement("strong")
       const excerpt = document.createElement("span")
       link.href = result.url
-      title.textContent = result.meta.title
+      title.textContent = result.title
       excerpt.innerHTML = result.excerpt
       link.append(title, excerpt)
       item.append(link)