Optimize processImportSpecifier by computing shouldFollowImportsFromFile once per file

[Copilot]

Description

processImportSpecifier was calling shouldFollowImportsFromFile(filePath, forceFollowImports) once for every import specifier in a file, even though the result only depends on filePath and forceFollowImports. Hoist that evaluation into processFile and pass the boolean result down:

• processFile now computes shouldFollow once before iterating specifiers.
• processImportSpecifier now accepts a shouldFollow: boolean argument instead of forceFollowImports: boolean.

// Before
await Promise.all(
  specifiers.map((specifier) =>
    processImportSpecifier(filePath, specifier, forceFollowImports)
  )
);

// After
const shouldFollow = await shouldFollowImportsFromFile(filePath, forceFollowImports);
// ...
await Promise.all(
  specifiers.map((specifier) =>
    processImportSpecifier(filePath, specifier, shouldFollow)
  )
);

How did you test your changes?

• Ran the @workflow/builders test suite (fast-discovery.test.ts and related files pass).
• Verified the change with Biome lint/format on the modified file.

PR Checklist - Required to merge

• 📦 pnpm changeset was run to create a changelog for this PR
  • Use the correct semver bump type: patch for bug fixes, minor for new features, major for breaking changes.
  • Use pnpm changeset --empty if you are changing documentation or workbench apps
• 🔒 DCO sign-off passes (run git commit --signoff on your commits)
• 📝 Ping @vercel/workflow in a comment once the PR is ready, and above checklist is complete

[vercel]

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Project	Deployment	Actions	Updated (UTC)
example-nextjs-workflow-turbopack	Ready	Preview, Comment	Jul 23, 2026 10:49pm
example-nextjs-workflow-webpack	Ready	Preview, Comment	Jul 23, 2026 10:49pm
example-workflow	Ready	Preview, Comment	Jul 23, 2026 10:49pm
workbench-astro-workflow	Ready	Preview, Comment	Jul 23, 2026 10:49pm
workbench-express-workflow	Ready	Preview, Comment	Jul 23, 2026 10:49pm
workbench-fastify-workflow	Ready	Preview, Comment	Jul 23, 2026 10:49pm
workbench-hono-workflow	Ready	Preview, Comment	Jul 23, 2026 10:49pm
workbench-nestjs-workflow	Ready	Preview, Comment	Jul 23, 2026 10:49pm
workbench-nitro-workflow	Ready	Preview, Comment	Jul 23, 2026 10:49pm
workbench-nuxt-workflow	Ready	Preview, Comment	Jul 23, 2026 10:49pm
workbench-sveltekit-workflow	Ready	Preview, Comment	Jul 23, 2026 10:49pm
workbench-tanstack-start-workflow	Ready	Preview, Comment	Jul 23, 2026 10:49pm
workbench-vite-workflow	Ready	Preview, Comment	Jul 23, 2026 10:49pm
workflow-docs	Ready	Preview, Comment, Open in v0	Jul 23, 2026 10:49pm
workflow-swc-playground	Ready	Preview, Comment	Jul 23, 2026 10:49pm
workflow-tarballs	Ready	Preview, Comment	Jul 23, 2026 10:49pm
workflow-web	Ready	Preview, Comment	Jul 23, 2026 10:49pm

[changeset-bot]

🦋 Changeset detected

Latest commit: 10fad5b

The changes in this PR will be included in the next version bump.

This PR includes changesets to release 16 packages

Name	Type
@workflow/builders	Patch
@workflow/astro	Patch
@workflow/cli	Patch
@workflow/nest	Patch
@workflow/next	Patch
@workflow/nitro	Patch
@workflow/nuxt	Patch
@workflow/rollup	Patch
@workflow/sveltekit	Patch
@workflow/vite	Patch
@workflow/vitest	Patch
workflow	Patch
@workflow/world-testing	Patch
@workflow/core	Patch
@workflow/web-shared	Patch
@workflow/web	Patch

Not sure what this means? Click here to learn what changesets are.

Click here if you're a maintainer who wants to add another changeset to this PR

[github-actions]

🧪 E2E Test Results

✅ All tests passed

Summary

	Passed	Failed	Skipped	Total
✅ ▲ Vercel Production	1455	0	239	1694
✅ 💻 Local Development	1621	0	227	1848
✅ 📦 Local Production	1621	0	227	1848
✅ 🐘 Local Postgres	1621	0	227	1848
✅ 🪟 Windows	154	0	0	154
✅ 📋 Other	1020	0	212	1232
✅ vercel-multi-region	27	0	0	27
Total	7519	0	1132	8651

Details by Category

✅ ▲ Vercel Production

App	Passed	Failed	Skipped
✅ astro	126	0	28
✅ example	126	0	28
✅ express	126	0	28
✅ fastify	126	0	28
✅ hono	126	0	28
✅ nextjs-turbopack	151	0	3
✅ nextjs-webpack	151	0	3
✅ nitro	126	0	28
✅ nuxt	126	0	28
✅ sveltekit	145	0	9
✅ vite	126	0	28

✅ 💻 Local Development

App	Passed	Failed	Skipped
✅ astro-stable	128	0	26
✅ express-stable	128	0	26
✅ fastify-stable	128	0	26
✅ hono-stable	128	0	26
✅ nextjs-turbopack-canary	135	0	19
✅ nextjs-turbopack-stable	154	0	0
✅ nextjs-webpack-canary	135	0	19
✅ nextjs-webpack-stable	154	0	0
✅ nitro-stable	128	0	26
✅ nuxt-stable	128	0	26
✅ sveltekit-stable	147	0	7
✅ vite-stable	128	0	26

✅ 📦 Local Production

App	Passed	Failed	Skipped
✅ astro-stable	128	0	26
✅ express-stable	128	0	26
✅ fastify-stable	128	0	26
✅ hono-stable	128	0	26
✅ nextjs-turbopack-canary	135	0	19
✅ nextjs-turbopack-stable	154	0	0
✅ nextjs-webpack-canary	135	0	19
✅ nextjs-webpack-stable	154	0	0
✅ nitro-stable	128	0	26
✅ nuxt-stable	128	0	26
✅ sveltekit-stable	147	0	7
✅ vite-stable	128	0	26

✅ 🐘 Local Postgres

App	Passed	Failed	Skipped
✅ astro-stable	128	0	26
✅ express-stable	128	0	26
✅ fastify-stable	128	0	26
✅ hono-stable	128	0	26
✅ nextjs-turbopack-canary	135	0	19
✅ nextjs-turbopack-stable	154	0	0
✅ nextjs-webpack-canary	135	0	19
✅ nextjs-webpack-stable	154	0	0
✅ nitro-stable	128	0	26
✅ nuxt-stable	128	0	26
✅ sveltekit-stable	147	0	7
✅ vite-stable	128	0	26

✅ 🪟 Windows

App	Passed	Failed	Skipped
✅ nextjs-turbopack	154	0	0

✅ 📋 Other

App	Passed	Failed	Skipped
✅ e2e-local-dev-nest-stable	128	0	26
✅ e2e-local-dev-tanstack-start-	128	0	26
✅ e2e-local-postgres-nest-stable	128	0	26
✅ e2e-local-postgres-tanstack-start-	128	0	26
✅ e2e-local-prod-nest-stable	128	0	26
✅ e2e-local-prod-tanstack-start-	128	0	26
✅ e2e-vercel-prod-nest	126	0	28
✅ e2e-vercel-prod-tanstack-start	126	0	28

✅ vercel-multi-region

App	Passed	Failed	Skipped
✅ nextjs-turbopack	27	0	0

---

📋 View full workflow run

[github-actions]

📊 Workflow Benchmarks

commit 10fad5b · Thu, 23 Jul 2026 23:01:48 GMT · run logs

Backend: vercel · app: nextjs-turbopack

Metric	Scenario	Best (ms)	P75 (ms)	P90 (ms)	P99 (ms)	Samples
TTFS	step	1319 (+32%) 🔻	1415 🔴 (+29%) 🔻	1497 🔴 (+34%) 🔻	1866 🔴 (+10%)	30
TTFS	stream	412 (+9.0%)	1408 🔴 (+28%) 🔻	1482 🔴 (+31%) 🔻	1587 🔴 (+25%) 🔻	30
TTFS	hook + stream	1470 (+166%) 🔻	1728 🔴 (+23%) 🔻	1781 🔴 (+21%) 🔻	1897 🔴 (+28%) 🔻	30
STSO	1020 steps (1-20)	185 (+1.1%)	294 🔴 (+6.9%)	305 🔴 (+4.8%)	331 🔴 (±0%)	19
STSO	1020 steps (101-120)	198 (+3.1%)	322 🔴 (+1.6%)	567 🔴 (+21%) 🔻	2199 🔴 (+248%) 🔻	19
STSO	1020 steps (1001-1020)	483 (-4.2%)	573 🔴 (-4.0%)	599 🔴 (-9.1%)	816 🔴 (+12%)	19
WO	1020 steps	403452 (-3.3%)	403452 (-3.3%)	403452 (-3.3%)	403452 (-3.3%)	1
SL	stream latency	107 (+2.9%)	157 🔴 (-0.6%)	184 🔴 (-9.4%)	263 🔴 (-32%) 💚	30

📜 Previous results (1)

8c32b94

Wed, 22 Jul 2026 15:32:00 GMT · run logs

vercel / nextjs-turbopack

Metric	Scenario	Best (ms)	P75 (ms)	P90 (ms)	P99 (ms)	Samples
TTFS	step	146 (+20%) 🔻	415 🔴 (+73%) 🔻	2121 🔴 (+553%) 🔻	2620 🔴 (+508%) 🔻	30
TTFS	stream	136 (-12%)	304 🔴 (-10%)	2368 🔴 (+542%) 🔻	4518 🔴 (+876%) 🔻	30
TTFS	hook + stream	259 (-16%) 💚	405 🔴 (-12%)	511 🔴 (+0.6%)	2710 🔴 (+336%) 🔻	30
STSO	1020 steps (1-20)	170 (-11%)	289 🔴 (-1.7%)	331 🔴 (-1.8%)	416 🔴 (+19%) 🔻	19
STSO	1020 steps (101-120)	208 (-6.7%)	323 🔴 (+0.6%)	384 🔴 (-21%) 💚	412 🔴 (-18%) 💚	19
STSO	1020 steps (1001-1020)	513 (-15%) 💚	667 🔴 (-15%)	713 🔴 (-18%) 💚	921 🔴 (-17%) 💚	19
WO	1020 steps	441418 (-17%) 💚	441418 (-17%) 💚	441418 (-17%) 💚	441418 (-17%) 💚	1
SL	stream latency	86 (-4.4%)	142 🔴 (-5.3%)	226 🔴 (+25%) 🔻	402 🔴 (+76%) 🔻	30

_{Best/P75/P90/P99 deltas compare against the most recent benchmark run on main at the time of this run. 🔻 flags a delta worse than +15%, 💚 one better than −15%.}

_{Metrics — TTFS: time to first step body (in-deployment start() → first step body, deployment clocks) · STSO: step-to-step overhead (gap between consecutive step bodies) · WO: workflow overhead (whole-run time outside step bodies, in-deployment anchored) · SL: stream latency (in-deployment write → read propagation, readAt - writtenAt)}

_{Scenarios — step: one trivial no-op step, no stream; no hooks, so the run stays in turbo mode (in-process fast path) · stream: one streaming step; no hooks, so the run stays in turbo mode (in-process fast path) · hook + stream: registers a hook before one step, which exits turbo mode (dispatch path) · 1020 steps: 1020 trivial sequential steps; STSO is measured between consecutive steps in the given step ranges, and WO is the whole-run overhead outside step bodies · stream latency: parallel reader/writer steps on a dedicated stream; SL is the in-deployment write->read propagation (readAt - writtenAt)}

_{🔴 marks a percentile over its target (within target is left unmarked). Targets (p75/p90/p99, ms) — TTFS 200/300/600 · SL 50/60/125 · STSO (1-20) 20/30/60 · STSO (101-120) 30/45/90 · STSO (1001-1020) 40/60/120}

_{All metrics are measured from deployment-side timestamps only. Runs are triggered by an in-deployment route that stamps the anchor (clientStart) right before start(), so the CI runner’s request and its path through api.vercel.com sit outside every measured window. TTFS = in-deployment start() → first step body (turbo uses the in-process fast path, non-turbo the dispatch path), and includes the VQS dispatch hop plus any /flow cold start. STSO/WO are measured between step bodies on the deployment. SL is measured inside the workflow (parallel reader/writer steps), so it no longer includes the api.vercel.com read path.}

_{Cold starts are kept in the numbers on purpose — they are part of real bursty-workload latency. The workbench deployment cold-starts the /flow invocation for a large fraction of runs, inflating P75+; the Best column shows the fastest (warm-start) sample for comparison.}

[github-actions]

Backport PR opened against stable: #3086. (backport job run)