perf(eve): build a single Nitro app on Vercel by RihanArfan · Pull Request #1229 · vercel/eve

RihanArfan · 2026-07-27T00:13:12Z

Description

Currently two Nitro builds are ran during eve build when deploying to Vercel. Logic is prior to Nitro supporting modifying specific function's config nitrojs/nitro#4124, and Eve/Workflows requires queue triggers, so we were generating the workflow flow function separately and then copying this separate function build into the core Nitro build later.

Now we drop the standalone flow build and instead emit the workflow flow function from one Nitro build.

Benchmarked building weather-agent and it's:

33% faster on my Mac (see benchmark below)
Used ~30% less CPU during GHA CI (see report below)
In Vercel CI (and other CoW FS's that Node.js supports COPYFILE_FICLONE) the total combined function size on disk goes from 11.08MB (main) to 6.97 MB (branch) (numbers based on generated function sizes on main vs brach from a build on macOS)

How did you test your changes?

hyperfine --warmup 1 --runs 5 \
  --prepare 'cd <eve-main-worktree>/apps/fixtures/weather-agent && rm -rf .eve .vercel/output' \
  --command-name 'main (2 nitro builds)' \
  'cd <eve-main-worktree>/apps/fixtures/weather-agent && VERCEL=1 node <eve-main-worktree>/packages/eve/bin/eve.js build --skip-sandbox-prewarm' \
  --prepare 'cd <eve-branch-worktree>/apps/fixtures/weather-agent && rm -rf .eve .vercel/output' \
  --command-name 'branch (1 nitro build)' \
  'cd /<eve-branch-worktree>/apps/fixtures/weather-agent && VERCEL=1 node <eve-branch-worktree>/packages/eve/bin/eve.js build --skip-sandbox-prewarm'

Benchmark 1: main (2 nitro builds)
  Time (mean ± σ):      1.284 s ±  0.053 s    [User: 1.934 s, System: 0.587 s]
  Range (min … max):    1.240 s …  1.364 s    5 runs
 
Benchmark 2: branch (1 nitro build)
  Time (mean ± σ):     964.9 ms ±  23.8 ms    [User: 1376.8 ms, System: 410.3 ms]
  Range (min … max):   930.9 ms … 987.9 ms    5 runs
 
Summary
  branch (1 nitro build) ran
    1.33 ± 0.06 times faster than main (2 nitro builds)

PR Checklist

I linked an issue with prior discussion confirming this change is wanted
I ran the relevant checks from CONTRIBUTING.md
I added tests and documentation where relevant
I added a changeset if this touches the published eve package
DCO sign-off passes for every commit (git commit --signoff)

vercel · 2026-07-27T08:02:02Z

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Project	Deployment	Actions	Updated (UTC)
eve-docs	Ready	Preview, Comment, Open in v0	Jul 27, 2026 8:27am
eve-docs-1644	Ready	Preview, Comment, Open in v0	Jul 27, 2026 8:27am
eve-docs-4759	Ready	Preview, Comment, Open in v0	Jul 27, 2026 8:27am

github-actions · 2026-07-27T08:05:07Z

Bundle + Package Summary: `apps/fixtures/weather-agent`

Key takeaways

Bundle warning: function payloads grew 25.2%.
Runtime delta: function payloads 11.69 MB -> 14.63 MB (+2.94 MB ⚠️); 1 changed payload.

❌ Bundle Warning: Action Will Fail

This action will fail because the bundle warning policy was exceeded. Add the acknowledge-bundle-warning label to acknowledge the regression and allow the check to pass without regenerating this report.

Area	Warning	Details
Runtime	Total function bytes	11.69 MB -> 14.63 MB; +2.94 MB ⚠️ (25.2%) over limit 10.0%

Delta vs `main (632605f)`

Area	Metric	Baseline	Current	Delta
Package	Packed tarball	4.07 MB	4.06 MB	-4.1 kB ✅
Package	Unpacked publish size	14.77 MB	14.76 MB	-14.6 kB ✅
Package	Installed footprint	53.93 MB	53.91 MB	-14.6 kB ✅
Package	Published files	2775	2775	0
Package	Installed files	6015	6015	0
Runtime	Unique function payloads	2	2	0
Runtime	Total function bytes	11.69 MB	14.63 MB	+2.94 MB ⚠️
Runtime	Public routes	11	11	0

Changed function payloads vs main (632605f) (2)

Function	Status	Baseline	Current	Delta	Route changes
`functions/__server.func`	changed	4.41 MB	7.31 MB	+2.90 MB ⚠️	none
`functions/.well-known/workflow/v1/flow.func`	changed	7.27 MB	7.31 MB	+41.7 kB ⚠️	none

`eve init` install

Metric	Baseline	Current	Delta
Installed footprint	92.33 MB	92.32 MB	-14.6 kB ✅
Installed packages	122	122	0
dependencies	4	4	0
devDependencies	2	2	0
Dependency package bytes	29.05 MB	29.04 MB	-14.6 kB ✅
devDependency package bytes	5.04 MB	5.04 MB	0 B ➖

Build Metadata

Preset: vercel
Nitro: nitro@3.0.260610-beta
Output directory: apps/fixtures/weather-agent/.vercel/output
Build metadata timestamp: 2026-07-27T08:28:15.252Z
Route aliases: 11 public, 1 internal (12 total aliases)
Vercel routes in config: 14
Severity legend: 🔴 dominant/large, 🟠 notable, 🟡 watch, ⚪ small

Package Drill-Down

Package Details

Package: eve@0.27.6
Package directory: packages/eve
Tarball: 4.06 MB (eve-0.27.6.tgz)
Unpacked payload: 14.76 MB across 2775 published files
Installed footprint: 53.91 MB across 6015 installed files
Installed root package: 13.47 MB
Installed dependencies: 40.44 MB
Runtime dependencies: 1
Peer dependencies: 5 (4 optional)

Installed footprint is measured from an isolated temporary npm install of the packed tarball.

Heavy installed dependencies

@rolldown/binding-linux-x64-gnu: 18.96 MB (35.2%)
eve: 13.47 MB (25.0%)
ai: 6.43 MB (11.9%)
zod: 5.04 MB (9.3%)
nitro: 2.41 MB (4.5%)

Publish payload breakdown

Published file size
🟠 dist/src/compiled/experimental-ai-sdk-code-mo... [###.....................] 1.51 MB 10.2%
🟡 dist/src/compiled/@vercel/sandbox/index.js       [#.......................] 632.4 kB 4.3%
🟡 dist/src/compiled/_chunks/workflow/undici-C2Z... [#.......................] 502.4 kB 3.4%
🟡 dist/src/compiled/@chat-adapter/slack/index.js   [#.......................] 440.5 kB 3.0%
🟡 dist/src/compiled/@vercel/oidc/index.js          [#.......................] 379.5 kB 2.6%
🔴 Other published files                            [########################] 11.30 MB 76.5%

Installed footprint breakdown

Installed package size
🔴 @rolldown/binding-linux-x64-gnu [########################] 18.96 MB 35.2%
🔴 eve                             [#################.......] 13.47 MB 25.0%
🔴 ai                              [########................] 6.43 MB 11.9%
🔴 zod                             [######..................] 5.04 MB 9.3%
🟠 nitro                           [###.....................] 2.41 MB 4.5%
🟡 @ai-sdk/provider-utils          [#.......................] 852.0 kB 1.6%
🔴 Other installed packages        [#########...............] 6.75 MB 12.5%

Runtime dependencies (1)

Package	Range	Notes
`nitro`	`3.0.260610-beta`

Peer dependencies (5)

Package	Range	Notes
`@opentelemetry/api`	`^1.0.0`	optional peer
`ai`	`catalog:`
`braintrust`	`^3.0.0`	optional peer
`just-bash`	`^3.0.0`	optional peer
`microsandbox`	`^0.5.0`	optional peer

eve init install drill-down

`eve init` install details

Command: eve init my-agent
Package manager: npm
Installed footprint: 92.32 MB across 7883 installed files
Installed packages: 122 total (116 transitive-only)
dependencies: 4 direct packages totaling 29.04 MB
devDependencies: 2 direct packages totaling 5.04 MB
Other transitive package files: 58.24 MB

Installed footprint is measured from an isolated temporary eve init my-agent using the current packed eve tarball.

Heavy installed dependencies

@typescript/typescript-linux-x64: 27.95 MB (30.3%)
@rolldown/binding-linux-x64-gnu: 18.96 MB (20.5%)
eve: 13.47 MB (14.6%)
zod: 9.00 MB (9.7%)
ai: 6.43 MB (7.0%)

Installed footprint breakdown

Installed package size
🔴 @typescript/typescript-linux-x64 [########################] 27.95 MB 30.3%
🔴 @rolldown/binding-linux-x64-gnu  [################........] 18.96 MB 20.5%
🔴 eve                              [############............] 13.47 MB 14.6%
🔴 zod                              [########................] 9.00 MB 9.7%
🔴 ai                               [######..................] 6.43 MB 7.0%
🟠 @types/node                      [##......................] 2.54 MB 2.8%
🔴 Other installed packages         [############............] 13.97 MB 15.1%

dependencies (4)

Package	Range	Installed size	Share
`@vercel/connect`	`0.4.2`	135.8 kB	0.1%
`ai`	`^7.0.34`	6.43 MB	7.0%
`eve`	`file:eve-0.27.6.tgz`	13.47 MB	14.6%
`zod`	`4.4.3`	9.00 MB	9.7%

devDependencies (2)

Package	Range	Installed size	Share
`@types/node`	`24.x`	2.54 MB	2.8%
`typescript`	`7.0.2`	2.50 MB	2.7%

Function Drill-Down

Payload Size Graph

Unique function payload size and share of total
🔴 functions/.well-known/workflow/v1/flow.func     [########################] 7.31 MB 50.0%
🔴 functions/__server.func                         [########################] 7.31 MB 50.0%

Top Function Payloads

🟠 functions/.well-known/workflow/v1/flow.func • 1 public route • 7.31 MB

Metric	Value
Public routes	`/.well-known/workflow/v1/flow`
Runtime	`nodejs24.x`
Handler	`index.mjs`
Payload	7.31 MB
Function files	7.31 MB across 43 files
Traced dependencies	0 B
Signal	🟠 Bundled file `_chunks/runtime-artifacts.mjs` is 1.57 MB (21.5%)

🟠 🔎 Dependency Analysis

📦 Bundled files:

Bundled file size
🟠 _chunks/runtime-artifacts.mjs   [###############.........] 1.57 MB 21.5%
🟠 index.mjs                       [###########.............] 1.17 MB 16.0%
🟡 _chunks/world-vercel.mjs        [#########...............] 900.3 kB 12.3%
🟡 _chunks/sandbox.mjs             [#######.................] 767.6 kB 10.5%
🟡 _libs/@ai-sdk/gateway+[...].mjs [####....................] 432.5 kB 5.9%
🟠 Other bundled files             [########################] 2.47 MB 33.8%

🧾 Vercel Config

{
  "handler": "index.mjs",
  "launcherType": "Nodejs",
  "shouldAddHelpers": false,
  "supportsResponseStreaming": true,
  "runtime": "nodejs24.x",
  "maxDuration": "max",
  "experimentalTriggers": [
    {
      "type": "queue/v2beta",
      "topic": "__eve776561746865722d6167656e74_wkf_workflow_*",
      "consumer": "default",
      "retryAfterSeconds": 5,
      "initialDelaySeconds": 0
    }
  ],
  "environment": {
    "WORKFLOW_PRECONDITION_GUARD": "1"
  }
}

🟠 functions/__server.func • 10 public routes, 1 internal alias • 7.31 MB

Metric	Value
Public routes	`/` `/eve/v1/callback/[token]` `/eve/v1/connections/[name]/callback/[token]` `/eve/v1/health` `/eve/v1/info` `/eve/v1/session` `/eve/v1/session/[sessionId]` `/eve/v1/session/[sessionId]/cancel` `/eve/v1/session/[sessionId]/stream` `/eve/v1/session/reset`
Internal aliases	`/__server`
Runtime	`nodejs24.x`
Handler	`index.mjs`
Payload	7.31 MB
Function files	7.31 MB across 43 files
Traced dependencies	0 B
Signal	🟠 Bundled file `_chunks/runtime-artifacts.mjs` is 1.57 MB (21.5%)

🟠 🔎 Dependency Analysis

📦 Bundled files:

Bundled file size
🟠 _chunks/runtime-artifacts.mjs   [###############.........] 1.57 MB 21.5%
🟠 index.mjs                       [###########.............] 1.17 MB 16.0%
🟡 _chunks/world-vercel.mjs        [#########...............] 900.3 kB 12.3%
🟡 _chunks/sandbox.mjs             [#######.................] 767.6 kB 10.5%
🟡 _libs/@ai-sdk/gateway+[...].mjs [####....................] 432.5 kB 5.9%
🟠 Other bundled files             [########################] 2.47 MB 33.8%

🧾 Vercel Config

{
  "handler": "index.mjs",
  "launcherType": "Nodejs",
  "shouldAddHelpers": false,
  "supportsResponseStreaming": true,
  "runtime": "nodejs24.x"
}

Build Timing: `e2e/fixtures/agent-tools-sandbox`

This is an informational timing measurement inside eve build, from preflight through publication. Output-size measurement and profile writing are excluded.

Build mode: deployable Vercel build with sandbox template prewarm included.

Build pipeline: 2.91 s -> 1.60 s (-1.31 s) vs main (632605f).
Timing is informational: shared GitHub runners are too variable for a hard timing budget.

Detailed phase timings vs `main (632605f)`

Phase	Baseline	Current	Delta
`extension.check`	5.5 ms	9.5 ms	+4.0 ms
`project.resolve`	5.7 ms	3.5 ms	-2.2 ms
`workspace.create`	1.4 ms	1.2 ms	-0.2 ms
`host.prepare`	466.3 ms	158.9 ms	-307.4 ms
`vercel.service-prefix.resolve`	1.7 ms	1.7 ms	0.0 ms
`nitro.create`	—	178.5 ms	—
`sandbox.prewarm`	333.0 ms	175.2 ms	-157.8 ms
`nitro.cache.prepare`	—	0.3 ms	—
`nitro.prepare`	—	0.7 ms	—
`nitro.public-assets`	—	0.7 ms	—
`nitro.prerender`	—	0.5 ms	—
`nitro.bundle`	—	1.06 s	—
`nitro.cache.write`	—	0.3 ms	—
`agent-summary.emit`	0.5 ms	0.5 ms	0.0 ms
`nitro.close`	—	0.1 ms	—
`output.publish`	3.3 ms	3.3 ms	0.0 ms
`workspace.remove`	4.6 ms	1.9 ms	-2.7 ms
`nitro.app.create`	23.8 ms	—	—
`nitro.app.cache.prepare`	0.2 ms	—	—
`nitro.app.prepare`	0.8 ms	—	—
`nitro.app.public-assets`	0.7 ms	—	—
`nitro.app.prerender`	0.4 ms	—	—
`nitro.app.bundle`	679.9 ms	—	—
`nitro.app.cache.write`	0.3 ms	—	—
`nitro.flow.create`	180.6 ms	—	—
`nitro.flow.cache.prepare`	0.2 ms	—	—
`nitro.flow.prepare`	0.7 ms	—	—
`nitro.flow.public-assets`	0.2 ms	—	—
`nitro.flow.prerender`	0.0 ms	—	—
`nitro.flow.bundle`	1.05 s	—	—
`nitro.flow.cache.write`	0.3 ms	—	—
`nitro.flow.close`	0.2 ms	—	—
`workflow.emit`	156.6 ms	—	—
`nitro.app.close`	0.1 ms	—	—

Signed-off-by: Rihan Arfan <me@file.properties>

RihanArfan · 2026-07-27T09:41:22Z

In nitro-nightly and the next Nitro v3 release, we added reflink support (on Copy on Write filesystems) so in Vercel CI the separate function in the same Nitro doesn't actually equate to duplicate disk usage, and in fact would result in a smaller total function output size. nitrojs/nitro#4373

vercel Bot deployed to Preview – eve-docs-4759 July 27, 2026 08:03 View deployment

vercel Bot deployed to Preview – eve-docs-1644 July 27, 2026 08:03 View deployment

vercel Bot deployed to Preview – eve-docs July 27, 2026 08:03 View deployment

feat: merge nitro instances into singular on vercel builds

1d50bec

Signed-off-by: Rihan Arfan <me@file.properties>

RihanArfan force-pushed the rihan/single-nitro-build branch from cc7f43a to 1d50bec Compare July 27, 2026 08:25

vercel Bot temporarily deployed to Preview – eve-docs-1644 July 27, 2026 08:25 Inactive

vercel Bot temporarily deployed to Preview – eve-docs-4759 July 27, 2026 08:26 Inactive

Merge branch 'main' into rihan/single-nitro-build

ad5ae39

vercel Bot deployed to Preview – eve-docs-4759 July 27, 2026 08:27 View deployment

vercel Bot deployed to Preview – eve-docs-1644 July 27, 2026 08:27 View deployment

vercel Bot deployed to Preview – eve-docs July 27, 2026 08:27 View deployment

RihanArfan added the acknowledge-bundle-warning Acknowledge an intentional bundle footprint increase label Jul 27, 2026

RihanArfan marked this pull request as ready for review July 27, 2026 09:41

ctgowrie approved these changes Jul 27, 2026

View reviewed changes

ctgowrie merged commit 3c53306 into main Jul 27, 2026
138 of 141 checks passed

ctgowrie deleted the rihan/single-nitro-build branch July 27, 2026 12:25

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perf(eve): build a single Nitro app on Vercel - #1229

perf(eve): build a single Nitro app on Vercel#1229
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rihan/single-nitro-build

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Package Details

`eve init` install details

Payload Size Graph

Top Function Payloads

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Description

How did you test your changes?

PR Checklist

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Bundle + Package Summary: apps/fixtures/weather-agent

❌ Bundle Warning: Action Will Fail

Delta vs main (632605f)

eve init install

Package Details

eve init install details

Payload Size Graph

Top Function Payloads

Build Timing: e2e/fixtures/agent-tools-sandbox

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RihanArfan commented Jul 27, 2026 •

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Bundle + Package Summary: `apps/fixtures/weather-agent`

Delta vs `main (632605f)`

`eve init` install

`eve init` install details

Build Timing: `e2e/fixtures/agent-tools-sandbox`