close
Skip to content

Unify how server responses are written into the client cache - #96876

Merged
acdlite merged 1 commit into
acdlite/rsc-response-format/05-segment-prefetch-convergencefrom
acdlite/rsc-response-format/06-unify-response-writes
Aug 13, 2026
Merged

Unify how server responses are written into the client cache#96876
acdlite merged 1 commit into
acdlite/rsc-response-format/05-segment-prefetch-convergencefrom
acdlite/rsc-response-format/06-unify-response-writes

Conversation

@acdlite

@acdlite acdlite commented Aug 7, 2026 •
edited
Loading

Copy link
Copy Markdown
Contributor

Every flow that writes a server response into the client cache now goes through a single function, writeServerResponseIntoCache.

This is preparation for subsequent steps in this stack that migrate even more callers to this unified path.

While we're modifying it, fetchSegmentPrefetchesUsingDynamicRequest is renamed to fetchSegmentPrefetchesUsingRuntimeRequest: these responses are produced by a runtime request, and "dynamic" refers to non-cached data, which prefetch responses never contain.

One subtle fix that fell out of the unification: a runtime prefetch response that carries no transport data used to make the flow bail before writing anything; now the shared function rejects the pending entries it was given, the same as a build id mismatch.

@github-actions

github-actions Bot commented Aug 7, 2026 •
edited
Loading

Copy link
Copy Markdown
Contributor

Tests Passed

Commit: b44a4b0

@github-actions

github-actions Bot commented Aug 7, 2026 •
edited
Loading

Copy link
Copy Markdown
Contributor

Stats from current PR

🔴 3 regressions, 1 improvement

Metric Canary PR Change Trend
Webpack Build Time (cached) 25.734s 26.254s 🔴 +520ms (+2%) ▁▆▁▁█
Webpack Cold (First Request) 3.468s 3.605s 🔴 +137ms (+4%) ▄▇▂▁█
Webpack Warm (First Request) 3.550s 3.659s 🔴 +109ms (+3%) ▃▆▁▂▆
node_modules Size 554 MB 553 MB 🟢 344 kB (0%) ▁████
📊 All Metrics
📖 Metrics Glossary

Dev Server Metrics:

  • Listen = TCP port starts accepting connections
  • First Request = HTTP server returns successful response
  • Cold = Fresh build (no cache)
  • Warm = With cached build artifacts

Build Metrics:

  • Fresh = Clean build (no .next directory)
  • Cached = With existing .next directory

Change Thresholds:

  • Time: Changes < 50ms AND < 10%, OR < 2% are insignificant
  • Size: Changes < 1KB AND < 1% are insignificant
  • All other changes are flagged to catch regressions

⚡ Dev Server

Metric Canary PR Change Trend
Cold (Listen) 813ms 813ms ✓ ▁▇█▂▇
Cold (Ready in log) 797ms 817ms ✓ ▁██▁█
Cold (First Request) 1.327s 1.373s ✓ ▁▇█▁█
Warm (Listen) 814ms 814ms ✓ ▁▇█▁▇
Warm (Ready in log) 808ms 815ms ✓ ▁██▁█
Warm (First Request) 1.368s 1.374s ✓ ▄█▁▄█
📦 Dev Server (Webpack) (Legacy)

📦 Dev Server (Webpack)

Metric Canary PR Change Trend
Cold (Listen) 813ms 814ms ✓ ▅▇▁▅█
Cold (Ready in log) 800ms 818ms ✓ ▃▅▁▂▇
Cold (First Request) 3.468s 3.605s 🔴 +137ms (+4%) ▄▇▂▁█
Warm (Listen) 814ms 864ms ✓ ▅▇▁▃▇
Warm (Ready in log) 798ms 823ms ✓ ▃▆▁▂▃
Warm (First Request) 3.550s 3.659s 🔴 +109ms (+3%) ▃▆▁▂▆

⚡ Production Builds

Metric Canary PR Change Trend
Fresh Build 6.550s 6.342s ✓ ▁▇█▁█
Cached Build 3.286s 3.328s ✓ ▁██▁▇
📦 Production Builds (Webpack) (Legacy)

📦 Production Builds (Webpack)

Metric Canary PR Change Trend
Fresh Build 25.644s 25.759s ✓ ▁▅▂▁▂
Cached Build 25.734s 26.254s 🔴 +520ms (+2%) ▁▆▁▁█
node_modules Size 554 MB 553 MB 🟢 344 kB (0%) ▁████
📦 Bundle Sizes

Bundle Sizes

⚡ Turbopack

Client

Main Bundles
Canary PR Change
03lzpt71kg1qg.js gzip 47 kB N/A -
03o8j4gdcreqe.js gzip 170 B N/A -
0405hwyamng46.js gzip 157 B N/A -
050icza-xjz0i.js gzip 5.73 kB N/A -
07jdby0ue616s.js gzip 450 B N/A -
0bjdc8muo74n5.js gzip 8.71 kB N/A -
0cz1d0mv5g_q7.js gzip 39.4 kB 39.4 kB ✓
0rci1f3or1a19.js gzip 13.3 kB N/A -
1_2x714--ii1i.js gzip 8.76 kB N/A -
1-3y752pkth5-.js gzip 10 kB N/A -
1elt1qium-r2m.css gzip 115 B 115 B ✓
1ewkwfyqom2y8.js gzip 158 B N/A -
1gyf22uwo685a.js gzip 158 B N/A -
1hxhm60beg9ej.js gzip 71.7 kB N/A -
1k6dd7su4cfei.js gzip 3.57 kB N/A -
1tf1phijqlx9j.js gzip 220 B 220 B ✓
1uzabyd1120a1.js gzip 8.71 kB N/A -
1vvaqv96pfhdm.js gzip 156 B N/A -
2-ufv8lc-g7gg.js gzip 10.6 kB N/A -
21kmjy_10x14f.js gzip 8.81 kB N/A -
28dhc6t85q1_p.js gzip 8.78 kB N/A -
2f-ilvczue-tp.js gzip 9.46 kB N/A -
2f1u17u5c8iny.js gzip 8.79 kB N/A -
2fklnf1x-tk68.js gzip 7.53 kB N/A -
2ifum2q5l9pnn.js gzip 155 B N/A -
2ikltg_8iegxw.js gzip 10.3 kB N/A -
2vxi673cz1-t4.js gzip 8.79 kB N/A -
2w4laifzt1o9q.js gzip 157 B N/A -
31dg94q7iv1fe.js gzip 160 B N/A -
38-q43pzktqhs.js gzip 1.46 kB N/A -
3j981cx6o_t11.js gzip 155 B N/A -
3ki92ksbh68ff.js gzip 152 B N/A -
3l9pr36yz-v2o.js gzip 161 B N/A -
3mrwxzed0ylgv.js gzip 13.1 kB N/A -
3nbojhxiy1qv_.js gzip 13.7 kB N/A -
3qn872h2wdhw7.js gzip 157 B N/A -
3ueg8wcmwx2u-.js gzip 156 B N/A -
41u5s3oe2-erp.js gzip 2.29 kB N/A -
445s_9hf8o7ao.js gzip 8.76 kB N/A -
44i244dmnulb-.js gzip 65.6 kB N/A -
turbopack-0d..9ejy.js gzip 3.74 kB 3.74 kB ✓
0-6bcj16ji2wf.js gzip N/A 10.6 kB -
056018sbl3xxg.js gzip N/A 156 B -
07ryk0jced-sc.js gzip N/A 8.78 kB -
0a9npihj78qly.js gzip N/A 157 B -
0jwho9fkrb_t3.js gzip N/A 2.29 kB -
0roh390ijzxa5.js gzip N/A 8.75 kB -
0rvbkygoup2y6.js gzip N/A 157 B -
0vex9w55ursqj.js gzip N/A 8.79 kB -
0z8h9xivq9k4i.js gzip N/A 156 B -
0zn9pf1bv9yel.js gzip N/A 156 B -
17oe55cu76cd7.js gzip N/A 450 B -
19om32e1m-0cq.js gzip N/A 160 B -
1din_zw2g87o2.js gzip N/A 168 B -
1drww5xikb-c-.js gzip N/A 9.46 kB -
1f2amrrz84mzg.js gzip N/A 151 B -
1g60xde_dv17t.js gzip N/A 8.79 kB -
1ioh62mzk8gy7.js gzip N/A 71.7 kB -
1o20zijn7kx7u.js gzip N/A 155 B -
1uzv47btzam64.js gzip N/A 5.73 kB -
1vy7n7wxv_rh5.js gzip N/A 8.81 kB -
1x0gfa0ls84m6.js gzip N/A 65.6 kB -
2-0i7pl900-ou.js gzip N/A 8.71 kB -
2-kcbngm7ik7y.js gzip N/A 8.75 kB -
29p5-xa4jmdhg.js gzip N/A 13.7 kB -
2jhbuzgq122u-.js gzip N/A 7.53 kB -
2kmj9_wi-lea_.js gzip N/A 46.3 kB -
2lpk5_hknut8q.js gzip N/A 13.1 kB -
2o4cibp3awtbw.js gzip N/A 3.56 kB -
2ugc69z0t0ypz.js gzip N/A 1.46 kB -
336mo8ag01xm6.js gzip N/A 156 B -
36dn8i-_3dnq5.js gzip N/A 10 kB -
3fljpmwcjxqhx.js gzip N/A 10.3 kB -
3gz44skqdlsrb.js gzip N/A 8.71 kB -
3q5e1j1558-w2.js gzip N/A 155 B -
3y9tus7kb5su0.js gzip N/A 13.3 kB -
446udw0vqke67.js gzip N/A 157 B -
44zkt6f12xfx-.js gzip N/A 162 B -
Total 401 kB 401 kB ✅ -729 B

Server

Middleware
Canary PR Change
middleware-b..fest.js gzip 1.06 kB 1.06 kB ✓
Total 1.06 kB 1.06 kB ⚠️ +2 B
Build Details
Build Manifests
Canary PR Change
_buildManifest.js gzip 878 B 878 B ✓
Total 878 B 878 B ✓
Build Cache
Canary PR Change
00000001.sst gzip 13.4 MB 12.6 MB 🟢 794 kB (-6%)
00000002.sst gzip 14.7 MB 14.6 MB 🟢 84.8 kB (-1%)
00000003.sst gzip 14.6 MB 14.2 MB 🟢 346 kB (-2%)
00000004.sst gzip 12.5 MB 13.7 MB 🔴 +1.22 MB (+10%)
00000005.sst gzip 10.2 MB 10.2 MB 🟢 30.7 kB (0%)
00000006.sst gzip 2.8 MB 2.8 MB ✓
00000007.sst gzip 59 B 59 B ✓
00000008.meta gzip 89 B 89 B ✓
00000009.meta gzip 298 kB 298 kB ✓
00000010.meta gzip 298 kB 298 kB ✓
00000011.meta gzip 298 kB 298 kB ✓
00000012.sst gzip 51.8 kB 51.8 kB ✓
00000013.sst gzip 1.79 MB 1.8 MB 🔴 +8.44 kB (+0%)
00000014.sst gzip 59 B 59 B ✓
00000015.meta gzip 116 B 116 B ✓
00000016.meta gzip 326 kB 326 kB ✓
00000017.meta gzip 405 kB 405 kB ✓
00000018.sst gzip 52.5 kB 52.4 kB ✓
00000019.sst gzip 1.38 MB 1.39 MB 🔴 +10.9 kB (+1%)
00000020.sst gzip 59 B 59 B ✓
00000021.meta gzip 116 B 116 B ✓
00000022.meta gzip 326 kB 326 kB ✓
00000023.meta gzip 372 kB 371 kB ✓
00000024.sst gzip 52.6 kB 52.5 kB ✓
00000025.sst gzip 1.38 MB 1.39 MB 🔴 +10.9 kB (+1%)
00000026.sst gzip 59 B 59 B ✓
00000027.meta gzip 116 B 116 B ✓
00000028.meta gzip 326 kB 326 kB ✓
00000029.meta gzip 372 kB 371 kB ✓
00000030.sst gzip 51.9 kB 51.9 kB ✓
00000031.sst gzip 1.38 MB 1.39 MB 🔴 +11 kB (+1%)
00000032.sst gzip 59 B 59 B ✓
00000033.meta gzip 116 B 116 B ✓
00000034.meta gzip 326 kB 326 kB ✓
00000035.meta gzip 372 kB 371 kB ✓
00000036.sst gzip 52.4 kB 52.3 kB ✓
00000037.sst gzip 1.38 MB 1.39 MB 🔴 +10.9 kB (+1%)
00000038.sst gzip 59 B 59 B ✓
00000039.meta gzip 116 B 116 B ✓
00000040.meta gzip 326 kB 326 kB ✓
00000041.meta gzip 372 kB 371 kB ✓
CURRENT gzip 92 B 94 B 🔴 +2 B (+2%)
LOG gzip 662 B 666 B ✓
Total 80.2 MB 80.2 MB ⚠️ +11.9 kB

📦 Webpack

Client

Main Bundles
Canary PR Change
3322-HASH.js gzip 66.1 kB N/A -
4191.HASH.js gzip 169 B N/A -
7920-HASH.js gzip 4.67 kB N/A -
9784-HASH.js gzip 5.63 kB N/A -
b1ad9f4c-HASH.js gzip 63.4 kB N/A -
framework-HASH.js gzip 59.7 kB 59.7 kB ✓
main-app-HASH.js gzip 255 B 252 B 🟢 3 B (-1%)
main-HASH.js gzip 40.1 kB 40.1 kB ✓
webpack-HASH.js gzip 1.68 kB 1.68 kB ✓
3577.HASH.js gzip N/A 168 B -
578-HASH.js gzip N/A 66.1 kB -
8590-HASH.js gzip N/A 5.61 kB -
9750-HASH.js gzip N/A 4.68 kB -
a8984546-HASH.js gzip N/A 63.4 kB -
Total 242 kB 242 kB ✅ -80 B
Polyfills
Canary PR Change
polyfills-HASH.js gzip 39.4 kB 39.4 kB ✓
Total 39.4 kB 39.4 kB ✓
Pages
Canary PR Change
_app-HASH.js gzip 194 B 193 B ✓
_error-HASH.js gzip 181 B 182 B ✓
css-HASH.js gzip 334 B 331 B ✓
dynamic-HASH.js gzip 1.81 kB 1.81 kB ✓
edge-ssr-HASH.js gzip 255 B 253 B ✓
head-HASH.js gzip 349 B 351 B ✓
hooks-HASH.js gzip 382 B 384 B ✓
image-HASH.js gzip 581 B 582 B ✓
index-HASH.js gzip 260 B 259 B ✓
link-HASH.js gzip 2.48 kB 2.48 kB ✓
routerDirect..HASH.js gzip 317 B 318 B ✓
script-HASH.js gzip 384 B 386 B ✓
withRouter-HASH.js gzip 316 B 315 B ✓
1afbb74e6ecf..834.css gzip 106 B 106 B ✓
Total 7.95 kB 7.96 kB ⚠️ +4 B

Server

Edge SSR
Canary PR Change
edge-ssr.js gzip 129 kB 129 kB ✓
page.js gzip 294 kB 294 kB ✓
Total 423 kB 423 kB ✅ -268 B
Middleware
Canary PR Change
middleware-b..fest.js gzip 618 B 615 B ✓
middleware-r..fest.js gzip 156 B 156 B ✓
middleware.js gzip 45.8 kB 45.4 kB ✓
edge-runtime..pack.js gzip 842 B 842 B ✓
Total 47.4 kB 47 kB ✅ -360 B
Build Details
Build Manifests
Canary PR Change
_buildManifest.js gzip 717 B 718 B ✓
Total 717 B 718 B ⚠️ +1 B
Build Cache
Canary PR Change
0.pack gzip 4.81 MB 4.79 MB 🟢 19.3 kB (0%)
index.pack gzip 122 kB 121 kB ✓
index.pack.old gzip 123 kB 121 kB 🟢 1.95 kB (-2%)
Total 5.05 MB 5.03 MB ✅ -22 kB

🔄 Shared (bundler-independent)

Runtimes
Canary PR Change
app-page-exp...dev.js gzip 375 kB 374 kB ✓
app-page-exp..prod.js gzip 207 kB 207 kB ✓
app-page-tur...dev.js gzip 375 kB 374 kB ✓
app-page-tur..prod.js gzip 207 kB 206 kB ✓
app-page-tur...dev.js gzip 371 kB 370 kB ✓
app-page-tur..prod.js gzip 205 kB 204 kB ✓
app-page.run...dev.js gzip 371 kB 370 kB ✓
app-page.run..prod.js gzip 205 kB 204 kB ✓
app-route-ex...dev.js gzip 82.9 kB 82.9 kB ✓
app-route-ex..prod.js gzip 56.1 kB 56.1 kB ✓
app-route-tu...dev.js gzip 83 kB 83 kB ✓
app-route-tu..prod.js gzip 56.1 kB 56.1 kB ✓
app-route-tu...dev.js gzip 82.5 kB 82.5 kB ✓
app-route-tu..prod.js gzip 55.9 kB 55.9 kB ✓
app-route.ru...dev.js gzip 82.5 kB 82.5 kB ✓
app-route.ru..prod.js gzip 55.8 kB 55.8 kB ✓
dev-validati...dev.js gzip 134 kB 134 kB ✓
dev-validati...dev.js gzip 134 kB 134 kB ✓
dev-validati...dev.js gzip 132 kB 132 kB ✓
dev-validati...dev.js gzip 132 kB 132 kB ✓
dist_client_...dev.js gzip 324 B 324 B ✓
dist_client_...dev.js gzip 326 B 326 B ✓
dist_client_...dev.js gzip 318 B 318 B ✓
dist_client_...dev.js gzip 317 B 317 B ✓
pages-api-tu...dev.js gzip 46.4 kB 46.4 kB ✓
pages-api-tu..prod.js gzip 34.6 kB 34.6 kB ✓
pages-api.ru...dev.js gzip 46.4 kB 46.4 kB ✓
pages-api.ru..prod.js gzip 34.5 kB 34.5 kB ✓
pages-turbo....dev.js gzip 55.2 kB 55.2 kB ✓
pages-turbo...prod.js gzip 40.1 kB 40.1 kB ✓
pages.runtim...dev.js gzip 55.1 kB 55.1 kB ✓
pages.runtim..prod.js gzip 40.1 kB 40.1 kB ✓
server.runti..prod.js gzip 67.1 kB 67.1 kB ✓
use-cache-pr...dev.js gzip 72.6 kB 72.6 kB ✓
use-cache-pr...dev.js gzip 72.6 kB 72.6 kB ✓
use-cache-pr...dev.js gzip 70.8 kB 70.8 kB ✓
use-cache-pr...dev.js gzip 70.8 kB 70.8 kB ✓
Total 4.11 MB 4.1 MB ✅ -7 kB
📝 Changed Files (8 files)

Files with changes:

  • app-page-exp..ntime.dev.js
  • app-page-exp..time.prod.js
  • app-page-tur..ntime.dev.js
  • app-page-tur..time.prod.js
  • app-page-tur..ntime.dev.js
  • app-page-tur..time.prod.js
  • app-page.runtime.dev.js
  • app-page.runtime.prod.js
View diffs
app-page-exp..ntime.dev.js 
failed to diff
app-page-exp..time.prod.js 
failed to diff
app-page-tur..ntime.dev.js 
failed to diff
app-page-tur..time.prod.js 
failed to diff
app-page-tur..ntime.dev.js 
failed to diff
app-page-tur..time.prod.js 
failed to diff
app-page.runtime.dev.js 
failed to diff
app-page.runtime.prod.js 
failed to diff
📎 Tarball URL 
https://vercel-packages.vercel.app/next/commits/b44a4b01ef78fe1b5660b79d1b170cfcb53cc753/next

Commit: b44a4b0

@acdlite
acdlite force-pushed the acdlite/rsc-response-format/06-unify-response-writes branch from 220bac8 to 3bf1c27 Compare August 10, 2026 20:34
@acdlite
acdlite force-pushed the acdlite/rsc-response-format/06-unify-response-writes branch from 3bf1c27 to ac9fee0 Compare August 10, 2026 23:08
@acdlite
acdlite marked this pull request as ready for review August 10, 2026 23:10
@acdlite
acdlite requested a review from ztanner August 10, 2026 23:10
@acdlite
acdlite force-pushed the acdlite/rsc-response-format/06-unify-response-writes branch from ac9fee0 to 861a757 Compare August 12, 2026 03:11
@acdlite
acdlite force-pushed the acdlite/rsc-response-format/06-unify-response-writes branch from 861a757 to bdd8b23 Compare August 13, 2026 01:34
@acdlite
Unify how server responses are written into the client cache
b44a4b0 
Every flow that writes a server response into the client cache now
goes through a single function, writeServerResponseIntoCache.

This is preparation for subsequent steps in this stack that migrate
even more callers to this unified path.

While we're modifying it, fetchSegmentPrefetchesUsingDynamicRequest
is renamed to fetchSegmentPrefetchesUsingRuntimeRequest: these
responses are produced by a runtime request, and "dynamic" refers to
non-cached data, which prefetch responses never contain.

One subtle fix that fell out of the unification: a runtime prefetch
response that carries no transport data used to make the flow bail
before writing anything; now the shared function rejects the pending
entries it was given, the same as a build id mismatch.
@acdlite
acdlite force-pushed the acdlite/rsc-response-format/06-unify-response-writes branch from bdd8b23 to b44a4b0 Compare August 13, 2026 20:35
@acdlite
acdlite merged commit 0c5881a into canary Aug 13, 2026
279 of 299 checks passed
@acdlite
acdlite deleted the acdlite/rsc-response-format/06-unify-response-writes branch August 13, 2026 22:18
Sign up for free to join this conversation on GitHub. Already have an account? Sign in to comment

Reviewers

@ztanner ztanner ztanner approved these changes

Assignees

No one assigned

Labels

None yet

Projects

None yet

Milestone

No milestone

Development

Successfully merging this pull request may close these issues.

2 participants

@acdlite @ztanner