docs(turbopack): Move singleton pattern documentation from mdbook to rustdoc

[bgw]

Copied over from https://turbopack-rust-docs.vercel.sh/turbo-engine/singleton.html with minimal changes.

[bgw]

Warning

This pull request is not mergeable via GitHub because a downstack PR is open. Once all requirements are satisfied, merge this PR as a stack on Graphite.
Learn more

• Turbopack: Remove the IntoTraitRef trait, make it an inherent method on Vc #91223
• docs(turbopack): Move singleton pattern documentation from mdbook to rustdoc #91175 👈 (View in Graphite)
• docs(turbopack): Migrate docs about traits from mdbook to rustdocs #91170
• docs(turbopack): Merge task input docs from mdbook into rustdocs #91136
• docs(turbopack): Move mdbook "tasks" docs over to turbo_tasks::function rustdoc #91132
• docs(turbopack): Merge the contents of the "cells" page in the mdbook with our rustdocs #91126
• docs(turbopack): Merge old turbo-tasks concept mdbook page with crate's top-level rustdoc #91120
• docs(turbopack): Copy over turbopack-trace-server docs #91111
• docs(contributing): Update setup in contributing/core/developing.md #91018
• canary

This stack of pull requests is managed by Graphite. Learn more about stacking.

[nextjs-bot]

Tests Passed

[codspeed-hq]

Merging this PR will degrade performance by 3.01%

❌ 1 regressed benchmark
✅ 16 untouched benchmarks
⏩ 3 skipped benchmarks¹

⚠️ Please fix the performance issues or acknowledge them on CodSpeed.

Performance Changes

	Mode	Benchmark	BASE	HEAD	Efficiency
❌	Simulation	packages-bundle.js[full]	1.2 s	1.2 s	-3.01%

---

_{Comparing bgw/turbo-tasks-singleton-docs (7ad9a2a) with canary (8850163)²}

Footnotes

1. 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. ↩

2. No successful run was found on bgw/turbo-tasks-traits-docs (5772998) during the generation of this report, so canary (8850163) was used instead as the comparison base. There might be some changes unrelated to this pull request in this report. ↩

[nextjs-bot]

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)	914ms	915ms	✓	▁██▁▁
Cold (Ready in log)	886ms	886ms	✓	▁██▁▁
Cold (First Request)	1.632s	1.642s	✓	▁██▃▁
Warm (Listen)	915ms	914ms	✓	▁██▁▁
Warm (Ready in log)	881ms	883ms	✓	▁██▁▁
Warm (First Request)	672ms	680ms	✓	▁██▁▁

📦 Dev Server (Webpack) (Legacy)

📦 Dev Server (Webpack)

Metric	Canary	PR	Change	Trend
Cold (Listen)	455ms	456ms	✓	▁▅▁▁▁
Cold (Ready in log)	436ms	437ms	✓	▁▄▃▃▃
Cold (First Request)	1.912s	1.922s	✓	▁▅▂▂▂
Warm (Listen)	457ms	455ms	✓	▁▄▁▁▁
Warm (Ready in log)	435ms	437ms	✓	▁▆▄▄▃
Warm (First Request)	1.914s	1.934s	✓	▁▆▂▂▂

⚡ Production Builds

Metric	Canary	PR	Change	Trend
Fresh Build	6.270s	6.309s	✓	▁█▇▁▁
Cached Build	6.145s	6.282s	✓	▁██▁▁

📦 Production Builds (Webpack) (Legacy)

📦 Production Builds (Webpack)

Metric	Canary	PR	Change	Trend
Fresh Build	14.339s	13.938s	✓	▁▅▁▁▁
Cached Build	14.403s	14.142s	✓	▁▅▁▁▁
node_modules Size	477 MB	477 MB	✓	▁▁▁▁▁

📦 Bundle Sizes

Bundle Sizes

⚡ Turbopack

Client

Main Bundles: **402 kB** → **402 kB** ✅ -25 B

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

Server

Middleware

	Canary	PR	Change
middleware-b..fest.js gzip	770 B	764 B	✓
Total	770 B	764 B	✅ -6 B

Build Details

Build Manifests

	Canary	PR	Change
_buildManifest.js gzip	450 B	451 B	✓
Total	450 B	451 B	⚠️ +1 B

📦 Webpack

Client

Main Bundles

	Canary	PR	Change
5528-HASH.js gzip	5.54 kB	N/A	-
6280-HASH.js gzip	59.6 kB	N/A	-
6335.HASH.js gzip	169 B	N/A	-
912-HASH.js gzip	4.59 kB	N/A	-
e8aec2e4-HASH.js gzip	62.6 kB	N/A	-
framework-HASH.js gzip	59.7 kB	59.7 kB	✓
main-app-HASH.js gzip	255 B	254 B	✓
main-HASH.js gzip	39.2 kB	39.2 kB	✓
webpack-HASH.js gzip	1.68 kB	1.68 kB	✓
262-HASH.js gzip	N/A	4.59 kB	-
2889.HASH.js gzip	N/A	169 B	-
5602-HASH.js gzip	N/A	5.55 kB	-
6948ada0-HASH.js gzip	N/A	62.6 kB	-
9544-HASH.js gzip	N/A	60.3 kB	-
Total	233 kB	234 kB	⚠️ +733 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	194 B	✓
_error-HASH.js gzip	183 B	180 B	🟢 3 B (-2%)
css-HASH.js gzip	331 B	330 B	✓
dynamic-HASH.js gzip	1.81 kB	1.81 kB	✓
edge-ssr-HASH.js gzip	256 B	256 B	✓
head-HASH.js gzip	351 B	352 B	✓
hooks-HASH.js gzip	384 B	383 B	✓
image-HASH.js gzip	580 B	581 B	✓
index-HASH.js gzip	260 B	260 B	✓
link-HASH.js gzip	2.51 kB	2.51 kB	✓
routerDirect..HASH.js gzip	320 B	319 B	✓
script-HASH.js gzip	386 B	386 B	✓
withRouter-HASH.js gzip	315 B	315 B	✓
1afbb74e6ecf..834.css gzip	106 B	106 B	✓
Total	7.98 kB	7.98 kB	✅ -1 B

Server

Edge SSR

	Canary	PR	Change
edge-ssr.js gzip	125 kB	125 kB	✓
page.js gzip	257 kB	257 kB	✓
Total	381 kB	382 kB	⚠️ +534 B

Middleware

	Canary	PR	Change
middleware-b..fest.js gzip	615 B	615 B	✓
middleware-r..fest.js gzip	156 B	155 B	✓
middleware.js gzip	43.9 kB	43.9 kB	✓
edge-runtime..pack.js gzip	842 B	842 B	✓
Total	45.5 kB	45.5 kB	✅ -40 B

Build Details

Build Manifests

	Canary	PR	Change
_buildManifest.js gzip	715 B	718 B	✓
Total	715 B	718 B	⚠️ +3 B

Build Cache

	Canary	PR	Change
0.pack gzip	4.08 MB	4.08 MB	🔴 +5.04 kB (+0%)
index.pack gzip	103 kB	105 kB	🔴 +1.96 kB (+2%)
index.pack.old gzip	102 kB	104 kB	🔴 +1.8 kB (+2%)
Total	4.28 MB	4.29 MB	⚠️ +8.79 kB

🔄 Shared (bundler-independent)

Runtimes

	Canary	PR	Change
app-page-exp...dev.js gzip	323 kB	323 kB	✓
app-page-exp..prod.js gzip	171 kB	171 kB	✓
app-page-tur...dev.js gzip	322 kB	322 kB	✓
app-page-tur..prod.js gzip	171 kB	171 kB	✓
app-page-tur...dev.js gzip	319 kB	319 kB	✓
app-page-tur..prod.js gzip	169 kB	169 kB	✓
app-page.run...dev.js gzip	319 kB	319 kB	✓
app-page.run..prod.js gzip	170 kB	170 kB	✓
app-route-ex...dev.js gzip	70.9 kB	70.9 kB	✓
app-route-ex..prod.js gzip	49.3 kB	49.3 kB	✓
app-route-tu...dev.js gzip	70.9 kB	70.9 kB	✓
app-route-tu..prod.js gzip	49.3 kB	49.3 kB	✓
app-route-tu...dev.js gzip	70.5 kB	70.5 kB	✓
app-route-tu..prod.js gzip	49.1 kB	49.1 kB	✓
app-route.ru...dev.js gzip	70.5 kB	70.5 kB	✓
app-route.ru..prod.js gzip	49 kB	49 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	43.3 kB	43.3 kB	✓
pages-api-tu..prod.js gzip	32.9 kB	32.9 kB	✓
pages-api.ru...dev.js gzip	43.2 kB	43.2 kB	✓
pages-api.ru..prod.js gzip	32.9 kB	32.9 kB	✓
pages-turbo....dev.js gzip	52.6 kB	52.6 kB	✓
pages-turbo...prod.js gzip	38.5 kB	38.5 kB	✓
pages.runtim...dev.js gzip	52.6 kB	52.6 kB	✓
pages.runtim..prod.js gzip	38.5 kB	38.5 kB	✓
server.runti..prod.js gzip	62 kB	62 kB	✓
Total	2.84 MB	2.84 MB	✅ -5 B

📎 Tarball URL

https://vercel-packages.vercel.app/next/commits/7ad9a2a5cdf00b962655d59e0d9993241dfbb07d/next