[Segment Cache] Add isHeadPartial

[acdlite]

Based on:

• [Segment Cache] Interception routes #73434
• [Segment Cache] Use LRU to manage cache data  #73486
• [Segment Cache] Add isPartial to segment prefetch  #73528

---

Similar to #73528, but for the head, which is delivered separately from the segments. We can only skip the dynamic request if this value is false.

[ijjk]

Tests Passed

[ijjk]

Stats from current PR

Default Build

General Overall increase ⚠️

	vercel/next.js canary	acdlite/next.js is-partial-head	Change
buildDuration	20.9s	18.8s	N/A
buildDurationCached	18.1s	15.9s	N/A
nodeModulesSize	409 MB	409 MB	⚠️ +36.8 kB
nextStartRea..uration (ms)	491ms	476ms	N/A

Client Bundles (main, webpack)

	vercel/next.js canary	acdlite/next.js is-partial-head	Change
1187-HASH.js gzip	50.1 kB	50.1 kB	N/A
8276.HASH.js gzip	169 B	168 B	N/A
8377-HASH.js gzip	5.3 kB	5.3 kB	N/A
bccd1874-HASH.js gzip	53 kB	53 kB	N/A
framework-HASH.js gzip	57.5 kB	57.5 kB	N/A
main-app-HASH.js gzip	232 B	235 B	N/A
main-HASH.js gzip	33.7 kB	33.7 kB	N/A
webpack-HASH.js gzip	1.71 kB	1.71 kB	N/A
Overall change	0 B	0 B	✓

Legacy Client Bundles (polyfills)

	vercel/next.js canary	acdlite/next.js is-partial-head	Change
polyfills-HASH.js gzip	39.4 kB	39.4 kB	✓
Overall change	39.4 kB	39.4 kB	✓

Client Pages

	vercel/next.js canary	acdlite/next.js is-partial-head	Change
_app-HASH.js gzip	193 B	193 B	✓
_error-HASH.js gzip	193 B	193 B	✓
amp-HASH.js gzip	513 B	511 B	N/A
css-HASH.js gzip	343 B	342 B	N/A
dynamic-HASH.js gzip	1.84 kB	1.84 kB	N/A
edge-ssr-HASH.js gzip	265 B	265 B	✓
head-HASH.js gzip	363 B	362 B	N/A
hooks-HASH.js gzip	393 B	392 B	N/A
image-HASH.js gzip	4.44 kB	4.43 kB	N/A
index-HASH.js gzip	268 B	268 B	✓
link-HASH.js gzip	2.35 kB	2.34 kB	N/A
routerDirect..HASH.js gzip	328 B	328 B	✓
script-HASH.js gzip	397 B	397 B	✓
withRouter-HASH.js gzip	323 B	326 B	N/A
1afbb74e6ecf..834.css gzip	106 B	106 B	✓
Overall change	1.75 kB	1.75 kB	✓

Client Build Manifests

	vercel/next.js canary	acdlite/next.js is-partial-head	Change
_buildManifest.js gzip	746 B	747 B	N/A
Overall change	0 B	0 B	✓

Rendered Page Sizes

	vercel/next.js canary	acdlite/next.js is-partial-head	Change
index.html gzip	523 B	524 B	N/A
link.html gzip	537 B	537 B	✓
withRouter.html gzip	519 B	521 B	N/A
Overall change	537 B	537 B	✓

Edge SSR bundle Size

	vercel/next.js canary	acdlite/next.js is-partial-head	Change
edge-ssr.js gzip	128 kB	128 kB	N/A
page.js gzip	202 kB	202 kB	N/A
Overall change	0 B	0 B	✓

Middleware size

	vercel/next.js canary	acdlite/next.js is-partial-head	Change
middleware-b..fest.js gzip	667 B	663 B	N/A
middleware-r..fest.js gzip	155 B	156 B	N/A
middleware.js gzip	31.1 kB	31.1 kB	N/A
edge-runtime..pack.js gzip	844 B	844 B	✓
Overall change	844 B	844 B	✓

Next Runtimes

	vercel/next.js canary	acdlite/next.js is-partial-head	Change
797-experime...dev.js gzip	322 B	322 B	✓
797.runtime.dev.js gzip	314 B	314 B	✓
app-page-exp...dev.js gzip	322 kB	322 kB	N/A
app-page-exp..prod.js gzip	127 kB	127 kB	N/A
app-page-tur..prod.js gzip	139 kB	140 kB	N/A
app-page-tur..prod.js gzip	135 kB	135 kB	N/A
app-page.run...dev.js gzip	312 kB	312 kB	N/A
app-page.run..prod.js gzip	122 kB	122 kB	N/A
app-route-ex...dev.js gzip	36.8 kB	36.8 kB	✓
app-route-ex..prod.js gzip	25 kB	25 kB	✓
app-route-tu..prod.js gzip	25 kB	25 kB	✓
app-route-tu..prod.js gzip	24.8 kB	24.8 kB	✓
app-route.ru...dev.js gzip	38.5 kB	38.5 kB	✓
app-route.ru..prod.js gzip	24.8 kB	24.8 kB	✓
pages-api-tu..prod.js gzip	9.56 kB	9.56 kB	✓
pages-api.ru...dev.js gzip	11.4 kB	11.4 kB	✓
pages-api.ru..prod.js gzip	9.56 kB	9.56 kB	✓
pages-turbo...prod.js gzip	21.3 kB	21.3 kB	✓
pages.runtim...dev.js gzip	27 kB	27 kB	✓
pages.runtim..prod.js gzip	21.3 kB	21.3 kB	✓
server.runti..prod.js gzip	916 kB	916 kB	✓
Overall change	1.19 MB	1.19 MB	✓

build cache

	vercel/next.js canary	acdlite/next.js is-partial-head	Change
0.pack gzip	2.04 MB	2.04 MB	N/A
index.pack gzip	146 kB	144 kB	N/A
Overall change	0 B	0 B	✓

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Commit: 0821b05