Turbopack: remove Stateful flag #88196

sokra · 2026-01-07T08:00:47Z

What?

Remove unused code

sokra · 2026-01-07T08:01:10Z

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nextjs-bot · 2026-01-07T08:01:13Z

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approve CI run for commit: 89d496d

Note: this should only be enabled once the PR is ready to go and can only be enabled by a maintainer

nextjs-bot · 2026-01-07T08:01:13Z

Allow CI Workflow Run

approve CI run for commit: 89d496d

Note: this should only be enabled once the PR is ready to go and can only be enabled by a maintainer

vercel

Additional Suggestion:

Undefined variable is_stateful used in verify_determinism check

View Details

📝 Patch Details

diff --git a/turbopack/crates/turbo-tasks-backend/src/backend/operation/update_cell.rs b/turbopack/crates/turbo-tasks-backend/src/backend/operation/update_cell.rs
index e5408cb1f1..3128fe87ff 100644
--- a/turbopack/crates/turbo-tasks-backend/src/backend/operation/update_cell.rs
+++ b/turbopack/crates/turbo-tasks-backend/src/backend/operation/update_cell.rs
@@ -75,8 +75,7 @@ impl UpdateCellOperation {
 
                 // Check if this assumption holds.
                 #[cfg(feature = "verify_determinism")]
-                if !is_stateful
-                    && matches!(verification_mode, VerificationMode::EqualityCheck)
+                if matches!(verification_mode, VerificationMode::EqualityCheck)
                     && content != task.get_cell_data(is_serializable_cell_content, cell)
                 {
                     let task_description = ctx.get_task_description(task_id);

Analysis

The code on line 78 of turbopack/crates/turbo-tasks-backend/src/backend/operation/update_cell.rs referenced an undefined variable is_stateful in a verify_determinism conditional check:

if !is_stateful
    && matches!(verification_mode, VerificationMode::EqualityCheck)
    && content != task.get_cell_data(is_serializable_cell_content, cell)

This variable was never defined in the run function, and inspection of the codebase shows that the Stateful flag and mark_stateful() method have been removed from the system. The is_stateful variable appears to be leftover code from before the Stateful flag removal.

According to the context, when the Stateful flag was removed, this code in UpdateCellOperation was supposed to be updated but wasn't. Since tasks are now always non-stateful (the Stateful flag no longer exists), the condition !is_stateful is always true and can be safely removed.

Fix Applied: Removed the !is_stateful && condition from line 78-79, leaving just the check for VerificationMode::EqualityCheck and the content comparison. This is logically correct since:

The Stateful flag no longer exists in the system
Tasks are now implicitly non-stateful
The determinism verification should always apply to all tasks

turbopack/crates/turbo-tasks/src/manager.rs

turbopack/crates/turbo-tasks-backend/src/backend/mod.rs

nextjs-bot · 2026-01-07T08:30:15Z

Stats from current PR

✅ No significant changes detected

📊 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)	455ms	455ms	✓	▃▅▃▃▁
Cold (First Request)	1.134s	1.144s	✓	█▁▇██
Warm (Listen)	456ms	457ms	✓	█▁▁█▁
Warm (First Request)	362ms	342ms	✓	▁▁▁▂█

📦 Dev Server (Webpack) (Legacy)

📦 Dev Server (Webpack)

Metric	Canary	PR	Change	Trend
Cold (Listen)	455ms	456ms	✓	▁▁▁▁▁
Cold (First Request)	1.815s	1.807s	✓	▂▁▁▂▂
Warm (Listen)	456ms	456ms	✓	▁▁▁▁▁
Warm (First Request)	1.827s	1.826s	✓	▂▁▁▂▂

⚡ Production Builds

Metric	Canary	PR	Change	Trend
Fresh Build	4.151s	4.147s	✓	▂▆▃▄▁
Cached Build	4.158s	4.162s	✓	▁▆▂▃▁

📦 Production Builds (Webpack) (Legacy)

📦 Production Builds (Webpack)

Metric	Canary	PR	Change	Trend
Fresh Build	13.845s	13.874s	✓	▁▁▁▃▂
Cached Build	13.900s	13.853s	✓	▁▁▁▃▂
node_modules Size	457 MB	457 MB	✓	█████

📦 Bundle Sizes

Bundle Sizes

⚡ Turbopack

Client

Main Bundles: **431 kB** → **431 kB** ⚠️ +2 B

82 files with content-based hashes (individual files not comparable between builds)

Server

Middleware

	Canary	PR	Change
middleware-b..fest.js gzip	785 B	788 B	✓
Total	785 B	788 B	⚠️ +3 B

Build Details

Build Manifests

	Canary	PR	Change
_buildManifest.js gzip	451 B	451 B	✓
Total	451 B	451 B	✓

📦 Webpack

Client

Main Bundles

	Canary	PR	Change
2086.HASH.js gzip	169 B	N/A	-
2161-HASH.js gzip	5.4 kB	N/A	-
2747-HASH.js gzip	4.48 kB	N/A	-
4322-HASH.js gzip	52.7 kB	N/A	-
ec793fe8-HASH.js gzip	62.3 kB	N/A	-
framework-HASH.js gzip	59.8 kB	59.8 kB	✓
main-app-HASH.js gzip	250 B	254 B	🔴 +4 B (+2%)
main-HASH.js gzip	38.6 kB	38.9 kB	✓
webpack-HASH.js gzip	1.68 kB	1.68 kB	✓
1596.HASH.js gzip	N/A	169 B	-
2658-HASH.js gzip	N/A	52.5 kB	-
6349-HASH.js gzip	N/A	4.46 kB	-
7019-HASH.js gzip	N/A	5.42 kB	-
b17a3386-HASH.js gzip	N/A	62.3 kB	-
Total	225 kB	225 kB	⚠️ +161 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	182 B	182 B	✓
css-HASH.js gzip	336 B	335 B	✓
dynamic-HASH.js gzip	1.8 kB	1.8 kB	✓
edge-ssr-HASH.js gzip	256 B	256 B	✓
head-HASH.js gzip	352 B	349 B	✓
hooks-HASH.js gzip	385 B	384 B	✓
image-HASH.js gzip	580 B	580 B	✓
index-HASH.js gzip	259 B	258 B	✓
link-HASH.js gzip	2.5 kB	2.51 kB	✓
routerDirect..HASH.js gzip	319 B	317 B	✓
script-HASH.js gzip	385 B	387 B	✓
withRouter-HASH.js gzip	316 B	315 B	✓
1afbb74e6ecf..834.css gzip	106 B	106 B	✓
Total	7.97 kB	7.96 kB	✅ -8 B

Server

Edge SSR

	Canary	PR	Change
edge-ssr.js gzip	124 kB	124 kB	✓
page.js gzip	240 kB	241 kB	✓
Total	364 kB	365 kB	⚠️ +1.04 kB

Middleware

	Canary	PR	Change
middleware-b..fest.js gzip	652 B	653 B	✓
middleware-r..fest.js gzip	155 B	156 B	✓
middleware.js gzip	32.7 kB	32.9 kB	✓
edge-runtime..pack.js gzip	842 B	842 B	✓
Total	34.4 kB	34.6 kB	⚠️ +190 B

Build Details

Build Manifests

	Canary	PR	Change
_buildManifest.js gzip	738 B	738 B	✓
Total	738 B	738 B	✓

Build Cache

	Canary	PR	Change
0.pack gzip	3.63 MB	3.64 MB	🔴 +6.86 kB (+0%)
index.pack gzip	99.9 kB	100 kB	✓
index.pack.old gzip	99.2 kB	99.5 kB	✓
Total	3.83 MB	3.84 MB	⚠️ +7.42 kB

🔄 Shared (bundler-independent)

Runtimes

	Canary	PR	Change
app-page-exp...dev.js gzip	303 kB	303 kB	✓
app-page-exp..prod.js gzip	158 kB	158 kB	✓
app-page-tur...dev.js gzip	303 kB	303 kB	✓
app-page-tur..prod.js gzip	158 kB	158 kB	✓
app-page-tur...dev.js gzip	299 kB	299 kB	✓
app-page-tur..prod.js gzip	156 kB	156 kB	✓
app-page.run...dev.js gzip	300 kB	300 kB	✓
app-page.run..prod.js gzip	156 kB	156 kB	✓
app-route-ex...dev.js gzip	68.7 kB	68.7 kB	✓
app-route-ex..prod.js gzip	47.5 kB	47.5 kB	✓
app-route-tu...dev.js gzip	68.7 kB	68.7 kB	✓
app-route-tu..prod.js gzip	47.6 kB	47.6 kB	✓
app-route-tu...dev.js gzip	68.3 kB	68.3 kB	✓
app-route-tu..prod.js gzip	47.3 kB	47.3 kB	✓
app-route.ru...dev.js gzip	68.3 kB	68.3 kB	✓
app-route.ru..prod.js gzip	47.3 kB	47.3 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	41.1 kB	41.1 kB	✓
pages-api-tu..prod.js gzip	31.2 kB	31.2 kB	✓
pages-api.ru...dev.js gzip	41 kB	41 kB	✓
pages-api.ru..prod.js gzip	31.2 kB	31.2 kB	✓
pages-turbo....dev.js gzip	50.8 kB	50.8 kB	✓
pages-turbo...prod.js gzip	38.2 kB	38.2 kB	✓
pages.runtim...dev.js gzip	50.7 kB	50.7 kB	✓
pages.runtim..prod.js gzip	38.2 kB	38.2 kB	✓
server.runti..prod.js gzip	62.2 kB	62.2 kB	✓
Total	2.68 MB	2.68 MB	⚠️ +2 B

📝 Changed Files (2 files)

Files with changes:

pages-api.ru..time.prod.js
pages.runtime.prod.js

View diffs

pages-api.ru..time.prod.js

Diff too large to display

pages.runtime.prod.js

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codspeed-hq · 2026-01-07T12:09:23Z

CodSpeed Performance Report

Merging this PR will not alter performance

_{Comparing sokra/remove-unused-stateful-flag (73fc223) with canary (0f9b732)}

Summary

✅ 17 untouched benchmarks
⏩ 3 skipped benchmarks¹

3 benchmarks were skipped, so the baseline results were used instead. If they were deleted from the codebase, click here and archive them to remove them from the performance reports. ↩

vercel

Additional Suggestion:

Undefined variable is_stateful used in verify_determinism check

View Details

📝 Patch Details

diff --git a/turbopack/crates/turbo-tasks-backend/src/backend/operation/update_cell.rs b/turbopack/crates/turbo-tasks-backend/src/backend/operation/update_cell.rs
index e5408cb1f1..3128fe87ff 100644
--- a/turbopack/crates/turbo-tasks-backend/src/backend/operation/update_cell.rs
+++ b/turbopack/crates/turbo-tasks-backend/src/backend/operation/update_cell.rs
@@ -75,8 +75,7 @@ impl UpdateCellOperation {
 
                 // Check if this assumption holds.
                 #[cfg(feature = "verify_determinism")]
-                if !is_stateful
-                    && matches!(verification_mode, VerificationMode::EqualityCheck)
+                if matches!(verification_mode, VerificationMode::EqualityCheck)
                     && content != task.get_cell_data(is_serializable_cell_content, cell)
                 {
                     let task_description = ctx.get_task_description(task_id);

Analysis

The code on line 78 of turbopack/crates/turbo-tasks-backend/src/backend/operation/update_cell.rs referenced an undefined variable is_stateful in a verify_determinism conditional check:

if !is_stateful
    && matches!(verification_mode, VerificationMode::EqualityCheck)
    && content != task.get_cell_data(is_serializable_cell_content, cell)

This variable was never defined in the run function, and inspection of the codebase shows that the Stateful flag and mark_stateful() method have been removed from the system. The is_stateful variable appears to be leftover code from before the Stateful flag removal.

According to the context, when the Stateful flag was removed, this code in UpdateCellOperation was supposed to be updated but wasn't. Since tasks are now always non-stateful (the Stateful flag no longer exists), the condition !is_stateful is always true and can be safely removed.

Fix Applied: Removed the !is_stateful && condition from line 78-79, leaving just the check for VerificationMode::EqualityCheck and the content comparison. This is logically correct since:

The Stateful flag no longer exists in the system
Tasks are now implicitly non-stateful
The determinism verification should always apply to all tasks

nextjs-bot · 2026-01-07T15:50:00Z

Tests Passed

graphite-app · 2026-01-07T19:52:31Z

Merge activity

Jan 7, 7:52 PM UTC: This pull request can not be added to the Graphite merge queue. Please try rebasing and resubmitting to merge when ready.
Jan 7, 7:52 PM UTC: Graphite disabled "merge when ready" on this PR due to: a merge conflict with the target branch; resolve the conflict and try again..
Jan 8, 8:25 AM UTC: @sokra merged this pull request with Graphite.

nextjs-bot added created-by: Turbopack team PRs by the Turbopack team. Turbopack Related to Turbopack with Next.js. labels Jan 7, 2026

sokra mentioned this pull request Jan 7, 2026

Turbopack: report changed env vars in tracing #88195

Merged

This was referenced Jan 7, 2026

Turbopack: parallelize making dependent tasks dirty #86755

Open

Turbopack: Use batch get request to read more efficient from database #87106

Merged

Turbopack: In CI only persist at the end #87316

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vercel bot reviewed Jan 7, 2026

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sokra marked this pull request as ready for review January 7, 2026 08:18

sokra requested a review from mischnic January 7, 2026 08:18

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sokra force-pushed the sokra/trace_env_diff branch from 5661e21 to dc67461 Compare January 7, 2026 11:44

sokra force-pushed the sokra/remove-unused-stateful-flag branch from 89d496d to a89fc7e Compare January 7, 2026 11:44

sokra force-pushed the sokra/trace_env_diff branch 2 times, most recently from d36032d to 42acf15 Compare January 7, 2026 13:12

sokra force-pushed the sokra/remove-unused-stateful-flag branch 2 times, most recently from e43fd0b to 630982c Compare January 7, 2026 14:29

sokra force-pushed the sokra/trace_env_diff branch from 42acf15 to 4244c77 Compare January 7, 2026 14:29

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sokra changed the base branch from sokra/trace_env_diff to graphite-base/88196 January 7, 2026 15:33

sokra force-pushed the graphite-base/88196 branch from 4244c77 to 117c33b Compare January 7, 2026 15:33

sokra force-pushed the sokra/remove-unused-stateful-flag branch from 912ab8a to e9e1566 Compare January 7, 2026 15:33

graphite-app bot changed the base branch from graphite-base/88196 to canary January 7, 2026 15:34

sokra force-pushed the sokra/remove-unused-stateful-flag branch from e9e1566 to f43c55a Compare January 7, 2026 15:34

Turbopack: remove Stateful flag

73fc223

sokra force-pushed the sokra/remove-unused-stateful-flag branch from f43c55a to 73fc223 Compare January 8, 2026 07:35

sokra merged commit b81a64c into canary Jan 8, 2026
306 of 309 checks passed

sokra deleted the sokra/remove-unused-stateful-flag branch January 8, 2026 08:25

Turbopack: remove Stateful flag #88196

Turbopack: remove Stateful flag #88196

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Stats from current PR

✅ No significant changes detected

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CodSpeed Performance Report

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