perf(workbench): preload workbench and warmup dev-server files

[gu-stav]

Description

Preload the module federation manifest using a Link HTTP header and HTML tags and warmup more workbench-related files in Vite.

Speeds up loading of workbench - the remoteUrl is known ahead of time. This reduces the waterfall of load manifest -> load entry to load entry.

Companion PR: https://github.com/sanity-io/workbench/pull/182

---

Note

Low Risk
Low risk: changes are limited to the workbench dev-server startup path and only add optional preloading/warmup behavior when a valid remote URL is configured.

Overview
Speeds up workbench startup by preloading the Module Federation manifest when SANITY_INTERNAL_WORKBENCH_REMOTE_URL is set: writeWorkbenchRuntime now injects preconnect + preload as=fetch hints into the generated index.html, and the Vite dev server adds a middleware that sets a matching Link preload header on / and /index.html.

Improves dev-server responsiveness by expanding Vite server.warmup.clientFiles to include additional workbench modules and by fire-and-forget fetching the remote manifest to warm the remote's transform/module graph. Tests are extended to cover the new warmup list and header/prefetch behavior.

^{Reviewed by Cursor Bugbot for commit 62b96d1. Bugbot is set up for automated code reviews on this repo. Configure here.}

[github-actions]

📦 Bundle Stats — @sanity/cli

Compared against feat/workbench (236d11ca)

@sanity/cli

Metric	Value	vs feat/workbench (236d11c)
Internal (raw)	2.1 KB	-
Internal (gzip)	799 B	-
Bundled (raw)	10.94 MB	-
Bundled (gzip)	2.05 MB	-
Import time	740ms	-2ms, -0.3%

bin:sanity

Metric	Value	vs feat/workbench (236d11c)
Internal (raw)	975 B	-
Internal (gzip)	460 B	-
Bundled (raw)	9.84 MB	-
Bundled (gzip)	1.77 MB	-
Import time	2.08s	-18ms, -0.9%

🗺️ View treemap · Artifacts

Details

• Import time regressions over 10% are flagged with ⚠️
• Sizes shown as raw / gzip 🗜️. Internal bytes = own code only. Total bytes = with all dependencies. Import time = Node.js cold-start median.

📦 Bundle Stats — @sanity/cli-core

Compared against feat/workbench (236d11ca)

Metric	Value	vs feat/workbench (236d11c)
Internal (raw)	95.5 KB	-
Internal (gzip)	22.5 KB	-
Bundled (raw)	21.62 MB	-
Bundled (gzip)	3.42 MB	-
Import time	700ms	-5ms, -0.8%

🗺️ View treemap · Artifacts

Details

• Import time regressions over 10% are flagged with ⚠️
• Sizes shown as raw / gzip 🗜️. Internal bytes = own code only. Total bytes = with all dependencies. Import time = Node.js cold-start median.

📦 Bundle Stats — create-sanity

Compared against feat/workbench (236d11ca)

Metric	Value	vs feat/workbench (236d11c)
Internal (raw)	976 B	-
Internal (gzip)	507 B	-
Bundled (raw)	50.7 KB	-
Bundled (gzip)	12.6 KB	-
Import time	❌ ChildProcess denied: node	-

Details

• Import time regressions over 10% are flagged with ⚠️
• Sizes shown as raw / gzip 🗜️. Internal bytes = own code only. Total bytes = with all dependencies. Import time = Node.js cold-start median.

[github-actions]

Coverage Delta

File	Statements
packages/@sanity/cli-core/src/config/cli/getCliConfig.ts	100.0% (±0%)
packages/@sanity/cli-core/src/config/cli/schemas.ts	100.0% (±0%)
packages/@sanity/cli-core/src/services/cliUserConfig.ts	100.0% (±0%)
packages/@sanity/cli-core/src/util/getSanityConfigDir.ts	66.7% (new)
packages/@sanity/cli/src/actions/build/buildApp.ts	95.1% (±0%)
packages/@sanity/cli/src/actions/build/buildStaticFiles.ts	97.6% (+ 1.0%)
packages/@sanity/cli/src/actions/build/buildStudio.ts	96.5% (±0%)
packages/@sanity/cli/src/actions/build/buildVendorDependencies.ts	67.4% (±0%)
packages/@sanity/cli/src/actions/build/getViteConfig.ts	100.0% (±0%)
packages/@sanity/cli/src/actions/build/writeSanityRuntime.ts	96.0% (+ 0.8%)
packages/@sanity/cli/src/actions/deploy/deployApp.ts	80.5% (±0%)
packages/@sanity/cli/src/actions/dev/devAction.ts	100.0% (±0%)
packages/@sanity/cli/src/actions/dev/devServerRegistry.ts	93.5% (new)
packages/@sanity/cli/src/actions/dev/extractDevServerManifest.ts	20.0% (new)
packages/@sanity/cli/src/actions/dev/getDevServerConfig.ts	100.0% (±0%)
packages/@sanity/cli/src/actions/dev/startAppDevServer.ts	100.0% (+ 13.0%)
packages/@sanity/cli/src/actions/dev/startDevManifestWatcher.ts	90.9% (new)
packages/@sanity/cli/src/actions/dev/startStudioDevServer.ts	100.0% (+ 5.0%)
packages/@sanity/cli/src/actions/dev/startWorkbenchDevServer.ts	98.5% (new)
packages/@sanity/cli/src/actions/dev/writeWorkbenchRuntime.ts	100.0% (new)
packages/@sanity/cli/src/actions/init/bootstrapLocalTemplate.ts	89.7% (±0%)
packages/@sanity/cli/src/actions/init/bootstrapTemplate.ts	0.0% (±0%)
packages/@sanity/cli/src/actions/init/createAppCliConfig.ts	100.0% (±0%)
packages/@sanity/cli/src/actions/init/createCliConfig.ts	100.0% (+ 50.0%)
packages/@sanity/cli/src/actions/init/createStudioConfig.ts	83.3% (±0%)
packages/@sanity/cli/src/actions/init/initAction.ts	97.2% (+ 0.1%)
packages/@sanity/cli/src/actions/init/scaffoldTemplate.ts	100.0% (±0%)
packages/@sanity/cli/src/actions/init/types.ts	100.0% (±0%)
packages/@sanity/cli/src/actions/manifest/extractCoreAppManifest.ts	93.1% (new)
packages/@sanity/cli/src/actions/manifest/extractManifest.ts	100.0% (±0%)
packages/@sanity/cli/src/actions/manifest/types.ts	100.0% (±0%)
packages/@sanity/cli/src/actions/manifest/writeManifestFile.ts	100.0% (±0%)
packages/@sanity/cli/src/commands/dev.ts	100.0% (±0%)
packages/@sanity/cli/src/commands/init.ts	100.0% (±0%)
packages/@sanity/cli/src/commands/manifest/extract.ts	100.0% (±0%)
packages/@sanity/cli/src/constants.ts	100.0% (new)
packages/@sanity/cli/src/prompts/init/federation.ts	100.0% (new)
packages/@sanity/cli/src/server/devServer.ts	94.1% (±0%)
packages/@sanity/cli/src/services/userApplications.ts	92.8% (±0%)

Comparing 39 changed files against main @ 09a30e25f3f6246f967245420f7a91ba764b3690

Overall Coverage

Metric	Coverage
Statements	84.5% (+ 0.3%)
Branches	74.5% (+ 0.4%)
Functions	84.3% (+ 0.3%)
Lines	85.0% (+ 0.4%)