docs: preload and accelerate local search

[karakanb]

Motivation

• The docs site uses VitePress local search which lazily loads the search component and index and uses a 200ms debounce, causing noticeable delay for our large local index when opening the search popup and when typing queries.

Description

• Add a Vite transform plugin fastLocalSearch in docs/.vitepress/config.mjs that injects an idle-time import('./VPLocalSearchBox.vue') to warm the local-search chunk so search UI opens without lazy-load delay.
• Preload the local search index by invoking all localSearchIndex loaders while the reader is browsing so the ~2MB index is available before the user opens search.
• Reduce the search debounce from { debounce: 200, immediate: true } to { debounce: 25, immediate: true } to tighten query-response latency.
• Add defensive checks that throw clear build-time errors if upstream VitePress internal strings change, preventing silent regressions.

Testing

• Ran npm run docs:build to validate the site build and asset generation, and it completed successfully.
• Ran git diff --check and git status --short to validate the working tree and produced no actionable issues.
• Attempted an automated search-performance measurement with Playwright (node .search-perf.cjs), but the headless Chromium/Playwright launch was blocked by the environment (snap/chromium and network-proxy download issues), so end-to-end timing could not be collected here.

---

Codex Task

[greptile-apps]

Prompt To Fix All With AI

### Issue 1
docs/.vitepress/config.mjs:52
**Handle preload loader rejections**

A failed background index import rejects without a handler, producing an unhandled promise rejection even though search can retry the loader when opened.

```suggestion
                    `${searchIndexDeclaration}\n\n// Download the index while the reader is browsing instead of after search opens.\nObject.values(localSearchIndex).forEach((load) => load().catch(() => {}))`,
```

### Issue 2
docs/.vitepress/config.mjs:22-25
**Shorten the plugin commentary**

This four-line comment restates the upstream behavior, motivation, and implementation effects rather than providing the repository-required concise, location-specific explanation.

```suggestion
// Preload and tune VitePress local search for the large documentation index.
```

---

For each issue above, determine whether it is valid and should be fixed. If so, fix it directly.

_{Reviews (1): Last reviewed commit: "docs: preload and accelerate local searc..." | Re-trigger Greptile}

[greptile-apps]

Handle preload loader rejections

A failed background index import rejects without a handler, producing an unhandled promise rejection even though search can retry the loader when opened.

Suggested change

	`${searchIndexDeclaration}\n\n// Download the index while the reader is browsing instead of after search opens.\nObject.values(localSearchIndex).forEach((load) => load())`,
	`${searchIndexDeclaration}\n\n// Download the index while the reader is browsing instead of after search opens.\nObject.values(localSearchIndex).forEach((load) => load().catch(() => {}))`,

Prompt To Fix With AI

This is a comment left during a code review.
Path: docs/.vitepress/config.mjs
Line: 52

Comment:
**Handle preload loader rejections**

A failed background index import rejects without a handler, producing an unhandled promise rejection even though search can retry the loader when opened.

```suggestion
                    `${searchIndexDeclaration}\n\n// Download the index while the reader is browsing instead of after search opens.\nObject.values(localSearchIndex).forEach((load) => load().catch(() => {}))`,
```

---

For each issue above, determine whether it is valid and should be fixed. If so, fix it directly.

[greptile-apps]

Shorten the plugin commentary

This four-line comment restates the upstream behavior, motivation, and implementation effects rather than providing the repository-required concise, location-specific explanation.

Suggested change

	// VitePress intentionally lazy-loads local search and waits 200 ms after each
	// keystroke. That is a good default for small sites, but our large local index
	// made opening and using search feel sluggish. Keep the search code and index
	// warm, and use a short debounce so interaction stays below a frame or two.
	// Preload and tune VitePress local search for the large documentation index.

Rule Used: What: Comments should be concise and targeted to s... (source)

Prompt To Fix With AI

This is a comment left during a code review.
Path: docs/.vitepress/config.mjs
Line: 22-25

Comment:
**Shorten the plugin commentary**

This four-line comment restates the upstream behavior, motivation, and implementation effects rather than providing the repository-required concise, location-specific explanation.

```suggestion
// Preload and tune VitePress local search for the large documentation index.
```

**Rule Used:** What: Comments should be concise and targeted to s... ([source](https://app.greptile.com/bruin/-/custom-context?memory=6adfbd2b-1b23-4560-9e00-6254e7cb7c70))

---

For each issue above, determine whether it is valid and should be fixed. If so, fix it directly.

Note: If this suggestion doesn't match your team's coding style, reply to this and let me know. I'll remember it for next time!