chore(eve): performance - measure turns and remove root overhead by AndrewBarba · Pull Request #2814 · vercel/eve

AndrewBarba · 2026-09-01T00:58:33Z

Summary

Related to #876. eve's deterministic Vercel Workflow stress fixture exposed multi-second turn latency but did not retain structured measurements. This PR adds versioned sequential and concurrent samples, an informational report in the GitHub job summary, and 30-day JSON/Markdown artifacts so every relevant PR leaves inspectable evidence.

It also removes caller-resolution, caller-bind, and caller-notification steps when serialized lineage proves the session is a root session. Delegated, task, callback, failure, and cancellation paths retain the existing caller protocol. Best-effort Workflow attributes start alongside result settlement, but remain joined before the durable step exits so cumulative writes cannot reorder or outlive the step.

The research plan records the critical-path attribution, low-risk waitUntil audit, independently pushed experiments, hosted result ledger, rejected alternatives, required Workflow primitives, and a paired base/head benchmark design.

Hosted result

The exact benchmark-base and current candidate stress jobs both completed successfully and uploaded raw reports:

Metric	Control `33468124247`	Candidate `33469404605`	Delta
Sequential mean	3.042 s	2.009 s	-34.0%
Sequential p50	3.036 s	2.008 s	-33.9%
Sequential p95	3.692 s	2.341 s	-36.6%
Concurrent second-turn p50	1.867 s	1.607 s	-13.9%
Turn-order slope	13.31 ms/turn	5.27 ms/turn	-60.4%

The root-only change reproduced independently at 2.036-second mean and 2.053-second p50 in run 33468608676, so it accounts for almost all of the combined improvement. Exact Workflow-world coverage confirms that two root turns omit one caller resolution, two binds, and two notifications, while the delegated two-turn path retains that 1 + 2 + 2 inventory and identical results.

These are close-in-time hosted A/Bs, not interleaved statistical proof. The new report is informational until the proposed paired benchmark establishes the platform noise floor. The full research ledger also records the SDK beta.47 regression, neutral readiness and retired-cleanup trials, failed polling child join, unsafe hook/attribute coalescing attempts, and a non-mergeable topology prototype that reproduced 0.799–0.828-second p50s.

Low-risk await audit

There is no additional safe ctx.waitUntil conversion in the current Workflow hot path. Channel routes already use Nitro's request lifetime; Workflow steps expose no supported equivalent. The stress fixture's instrumentation flush is an async no-op, Workflow already group-commits adjacent stream chunks, and detaching attributes, hook operations, terminal cleanup, or provider drains would weaken ordering, retry, cancellation, or invocation-lifetime guarantees. This PR does not import Workflow's private host helper or make correctness environment-dependent.

Validation

node --test scripts/workflow-stress-report.test.mjs — 3 passed
pnpm test:unit — 7,461 passed, 1 skipped
pnpm --filter eve exec vitest run --config vitest.integration.config.ts src/execution/workflow-entry.integration.test.ts — 17 passed
pnpm typecheck
pnpm lint — existing unrelated warnings only
pnpm guard:invariants
pnpm docs:check
hosted Vercel Workflow stress control, isolated root-only confirmation, and combined candidate jobs passed and retained reports
the latest-head Workflow stress rerun passed after the shared-project throttle cleared; p50 was 2.036 s and concurrent second-turn p50 was 1.526 s (run, artifact)
required CI, the lower-concurrency Vercel rerun, and Postgres passed on the latest head; the real-model Anthropic prompt-cache eval failed twice because the model returned an empty response instead of its expected tool call

Checklist

This change was requested or approved by a maintainer
I ran the relevant checks from CONTRIBUTING.md
I added tests and documentation where relevant
I added changesets for published eve behavior
DCO sign-off passes for every commit (git commit --signoff)

Signed-off-by: Andrew Barba <barba@hey.com>

vercel · 2026-09-01T00:58:39Z

The latest updates on your projects. Learn more about Vercel for GitHub.

Project	Deployment	Actions	Updated
eve-docs	Ready	Preview, v0	Sep 1, 2026 12:55pm UTC
eve-docs-4759	Ready	Preview, v0	Sep 1, 2026 12:55pm UTC
eve-pkg	Building	Preview, v0	Sep 1, 2026 12:55pm UTC

Signed-off-by: Andrew Barba <barba@hey.com>

github-actions · 2026-09-01T01:32:33Z

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

Key takeaways

No notable deltas vs main (e09c721).

Delta vs `main (e09c721)`

Area	Metric	Baseline	Current	Delta
Package	Packed tarball	8.54 MB	8.54 MB	+1.1 kB ⚠️
Package	Unpacked publish size	32.20 MB	32.20 MB	+2.1 kB ⚠️
Package	Installed footprint	77.22 MB	77.23 MB	+2.1 kB ⚠️
Package	Published files	3674	3676	+2
Package	Installed files	7509	7511	+2
Package	Installed package instances	35	35	0
Package	Distinct installed package names	34	34	0
Package	Installed dependency edges	53	53	0
Package	Installed optional peer edges	47	47	0
Runtime	Unique function payloads	2	2	0
Runtime	Total function bytes	19.86 MB	19.87 MB	+14.5 kB ⚠️
Runtime	Public routes	17	17	0

Changed function payloads vs main (e09c721) (2)

Function	Status	Baseline	Current	Delta	Route changes
`functions/__server.func`	changed	9.93 MB	9.94 MB	+7.2 kB ⚠️	none
`functions/.well-known/workflow/v1/flow.func`	changed	9.93 MB	9.94 MB	+7.2 kB ⚠️	none

`eve init` install

Metric	Baseline	Current	Delta
Installed footprint	115.66 MB	115.66 MB	+2.1 kB ⚠️
Installed packages	120	120	0
dependencies	4	4	0
devDependencies	2	2	0
Dependency package bytes	48.17 MB	48.17 MB	+2.1 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: 2026-09-01T12:55:32.720Z
Route aliases: 17 public, 1 internal (18 total aliases)
Vercel routes in config: 20
Severity legend: 🔴 dominant/large, 🟠 notable, 🟡 watch, ⚪ small

Package Drill-Down

Package Details

Package: eve@0.47.6
Package directory: packages/eve
Tarball: 8.54 MB (eve-0.47.6.tgz)
Unpacked payload: 32.20 MB across 3676 published files
Installed footprint: 77.23 MB across 7511 installed files
Installed root package: 30.74 MB
Installed dependencies: 46.48 MB
Installed package instances: 35
Distinct installed package names: 34
Installed dependency edges: 53
Installed optional peer edges: 47
Runtime dependencies: 2
Peer dependencies: 5 (4 optional)

Installed footprint is measured from an isolated temporary npm install of the packed tarball.
Graph metrics read only package.json files in package directories directly beneath a node_modules boundary, including nested boundaries. Each directory is one package instance; distinct names come from those manifests. Dependency edges count each unique name in dependencies or optionalDependencies per instance; optional peer edges count peerDependencies marked optional.

Heavy installed dependencies

eve: 30.74 MB (39.8%)
@rolldown/binding-linux-x64-gnu: 19.33 MB (25.0%)
ai: 6.89 MB (8.9%)
zod: 6.41 MB (8.3%)
undici: 3.50 MB (4.5%)

Publish payload breakdown

Published file size
🔴 dist/src/compiled/shadcn-registry/index.js       [#############...........] 9.76 MB 30.3%
🟠 dist/src/compiled/@photon-ai/chat-adapter-ime... [###.....................] 2.27 MB 7.1%
🟠 dist/src/compiled/@ai-sdk/code-mode/index.js     [#.......................] 1.03 MB 3.2%
🟡 dist/src/compiled/@vercel/blob/index.js          [#.......................] 901.8 kB 2.8%
🟡 dist/src/compiled/_chunks/workflow/undici-Dzn... [#.......................] 512.7 kB 1.6%
🔴 Other published files                            [########################] 17.73 MB 55.1%

Installed footprint breakdown

Installed package size
🔴 eve                             [########################] 30.74 MB 39.8%
🔴 @rolldown/binding-linux-x64-gnu [###############.........] 19.33 MB 25.0%
🔴 ai                              [#####...................] 6.89 MB 8.9%
🔴 zod                             [#####...................] 6.41 MB 8.3%
🟠 undici                          [###.....................] 3.50 MB 4.5%
🟠 nitro                           [##......................] 2.41 MB 3.1%
🔴 Other installed packages        [######..................] 7.94 MB 10.3%

Runtime dependencies (2)

Package	Range	Notes
`nitro`	`3.0.260610-beta`
`undici`	`8.9.0`

Peer dependencies (5)

Package	Range	Notes
`@opentelemetry/api`	`^1.0.0`	optional peer
`ai`	`catalog:`
`braintrust`	`^3.0.0`	optional peer
`just-bash`	`^3.1.0`	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: 115.66 MB across 9407 installed files
Installed packages: 120 total (114 transitive-only)
dependencies: 4 direct packages totaling 48.17 MB
devDependencies: 2 direct packages totaling 5.04 MB
Other transitive package files: 62.45 MB

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

Heavy installed dependencies

eve: 30.74 MB (26.6%)
@typescript/typescript-linux-x64: 27.95 MB (24.2%)
@rolldown/binding-linux-x64-gnu: 19.33 MB (16.7%)
zod: 10.37 MB (9.0%)
ai: 6.89 MB (6.0%)

Installed footprint breakdown

Installed package size
🔴 eve                              [########################] 30.74 MB 26.6%
🔴 @typescript/typescript-linux-x64 [######################..] 27.95 MB 24.2%
🔴 @rolldown/binding-linux-x64-gnu  [###############.........] 19.33 MB 16.7%
🔴 zod                              [########................] 10.37 MB 9.0%
🔴 ai                               [#####...................] 6.89 MB 6.0%
🟠 undici                           [###.....................] 3.50 MB 3.0%
🔴 Other installed packages         [#############...........] 16.88 MB 14.6%

dependencies (4)

Package	Range	Installed size	Share
`@vercel/connect`	`1.0.0`	167.9 kB	0.1%
`ai`	`^7.0.82`	6.89 MB	6.0%
`eve`	`file:eve-0.47.6.tgz`	30.74 MB	26.6%
`zod`	`4.5.4`	10.37 MB	9.0%

devDependencies (2)

Package	Range	Installed size	Share
`@types/node`	`24.x`	2.54 MB	2.2%
`typescript`	`7.0.2`	2.50 MB	2.2%

Function Drill-Down

Payload Size Graph

Unique function payload size and share of total
🔴 functions/.well-known/workflow/v1/flow.func     [########################] 9.94 MB 50.0%
🔴 functions/__server.func                         [########################] 9.94 MB 50.0%

Top Function Payloads

🟠 functions/.well-known/workflow/v1/flow.func • 1 public route • 9.94 MB

Metric	Value
Public routes	`/.well-known/workflow/v1/flow`
Runtime	`nodejs24.x`
Handler	`index.mjs`
Payload	9.94 MB
Function files	9.94 MB across 109 files
Traced dependencies	0 B
Signal	🟠 Bundled file `index.mjs` is 1.98 MB (19.9%)

🟠 🔎 Dependency Analysis

📦 Bundled files:

Bundled file size
🟠 index.mjs                       [##########..............] 1.98 MB 19.9%
🟡 _libs/undici.mjs                [#####...................] 980.5 kB 9.9%
🟡 _chunks/decode_jwt-Col8JOnf.mjs [###.....................] 702.6 kB 7.1%
🟡 _chunks/frames-Dl2Hcma4.mjs     [###.....................] 678.7 kB 6.8%
🟡 _chunks/chatgpt-model.mjs       [###.....................] 667.7 kB 6.7%
🔴 Other bundled files             [########################] 4.93 MB 49.6%

🧾 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 • 16 public routes, 1 internal alias • 9.94 MB

Metric	Value
Public routes	`/` `/eve/v1/activity/[token]` `/eve/v1/callback/[token]` `/eve/v1/connections/[name]/callback/[attemptId]/[token]` `/eve/v1/connections/[name]/callback/[token]` `/eve/v1/health` `/eve/v1/info` `/eve/v1/session` `/eve/v1/session/[parentSessionId]/subagents/[callId]/[childSessionId]/stream` `/eve/v1/session/[sessionId]` `/eve/v1/session/[sessionId]/cancel` `/eve/v1/session/[sessionId]/clear` `/eve/v1/session/[sessionId]/compact` `/eve/v1/session/[sessionId]/reset` `/eve/v1/session/[sessionId]/stream` `/eve/v1/task-input/[token]`
Internal aliases	`/__server`
Runtime	`nodejs24.x`
Handler	`index.mjs`
Payload	9.94 MB
Function files	9.94 MB across 109 files
Traced dependencies	0 B
Signal	🟠 Bundled file `index.mjs` is 1.98 MB (19.9%)

🟠 🔎 Dependency Analysis

📦 Bundled files:

Bundled file size
🟠 index.mjs                       [##########..............] 1.98 MB 19.9%
🟡 _libs/undici.mjs                [#####...................] 980.5 kB 9.9%
🟡 _chunks/decode_jwt-Col8JOnf.mjs [###.....................] 702.6 kB 7.1%
🟡 _chunks/frames-Dl2Hcma4.mjs     [###.....................] 678.7 kB 6.8%
🟡 _chunks/chatgpt-model.mjs       [###.....................] 667.7 kB 6.7%
🔴 Other bundled files             [########################] 4.93 MB 49.6%

🧾 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: 2.83 s -> 2.61 s (-219.9 ms) vs main (e09c721).
Timing is informational: shared GitHub runners are too variable for a hard timing budget.

Detailed phase timings vs `main (e09c721)`

Phase	Baseline	Current	Delta
`extension.check`	1.1 ms	10.7 ms	+9.6 ms
`project.resolve`	0.3 ms	0.3 ms	0.0 ms
`workspace.create`	0.7 ms	0.7 ms	0.0 ms
`host.prepare`	667.5 ms	594.4 ms	-73.1 ms
`vercel.service-prefix.resolve`	2.2 ms	2.4 ms	+0.2 ms
`nitro.create`	278.1 ms	300.8 ms	+22.7 ms
`sandbox.prewarm`	399.0 ms	228.6 ms	-170.4 ms
`nitro.cache.prepare`	0.3 ms	0.3 ms	0.0 ms
`nitro.prepare`	0.9 ms	0.8 ms	-0.1 ms
`nitro.public-assets`	0.8 ms	0.7 ms	-0.1 ms
`nitro.prerender`	0.6 ms	0.6 ms	0.0 ms
`nitro.bundle`	1.43 s	1.42 s	-12.0 ms
`nitro.cache.write`	0.3 ms	0.4 ms	+0.1 ms
`vercel.workflow-function.materialize`	44.7 ms	47.9 ms	+3.2 ms
`agent-summary.emit`	0.7 ms	0.8 ms	+0.1 ms
`nitro.close`	0.2 ms	0.2 ms	0.0 ms
`output.publish`	3.4 ms	3.2 ms	-0.2 ms
`workspace.remove`	2.1 ms	2.3 ms	+0.2 ms

Signed-off-by: Andrew Barba <barba@hey.com> (cherry picked from commit 863daf1)

Signed-off-by: Andrew Barba <barba@hey.com> (cherry picked from commit 5c3b078)

Signed-off-by: Andrew Barba <barba@hey.com> (cherry picked from commit cf580c1)

Signed-off-by: Andrew Barba <barba@hey.com> (cherry picked from commit c4e4fa0)

Signed-off-by: Andrew Barba <barba@hey.com> (cherry picked from commit 57e06b2)

Signed-off-by: Andrew Barba <barba@hey.com> (cherry picked from commit c05458d)

Signed-off-by: Andrew Barba <barba@hey.com>

chore(eve): track workflow turn performance

57b477d

Signed-off-by: Andrew Barba <barba@hey.com>

vercel Bot deployed to Preview – eve-pkg September 1, 2026 00:58 View deployment

vercel Bot deployed to Preview – eve-docs-4759 September 1, 2026 01:00 View deployment

vercel Bot deployed to Preview – eve-docs September 1, 2026 01:00 View deployment

perf(eve): overlap turn attribute persistence

5eb8d4d

Signed-off-by: Andrew Barba <barba@hey.com>

vercel Bot deployed to Preview – eve-pkg September 1, 2026 01:29 View deployment

AndrewBarba changed the title ~~chore(eve): performance - track Workflow turn latency~~ Sep 1, 2026

vercel Bot deployed to Preview – eve-docs-4759 September 1, 2026 01:30 View deployment

vercel Bot deployed to Preview – eve-docs September 1, 2026 01:30 View deployment

perf(eve): skip root caller steps

37d633e

Signed-off-by: Andrew Barba <barba@hey.com> (cherry picked from commit 863daf1)

vercel Bot deployed to Preview – eve-pkg September 1, 2026 04:19 View deployment

vercel Bot deployed to Preview – eve-docs-4759 September 1, 2026 04:20 View deployment

vercel Bot deployed to Preview – eve-docs September 1, 2026 04:21 View deployment

AndrewBarba added 7 commits September 1, 2026 00:24

docs(research): record root no-op benchmark

1bc7fa3

Signed-off-by: Andrew Barba <barba@hey.com> (cherry picked from commit 5c3b078)

docs(eve): record stream batching audit

15696a6

Signed-off-by: Andrew Barba <barba@hey.com> (cherry picked from commit cf580c1)

docs(eve): record attribute coalescing constraints

06e89cb

Signed-off-by: Andrew Barba <barba@hey.com> (cherry picked from commit c4e4fa0)

docs(eve): audit instrumentation flush critical path

82eb599

Signed-off-by: Andrew Barba <barba@hey.com> (cherry picked from commit 57e06b2)

docs(research): record child completion failure

43f6efd

Signed-off-by: Andrew Barba <barba@hey.com> (cherry picked from commit c05458d)

docs(research): synthesize hosted performance trials

d64c90b

Signed-off-by: Andrew Barba <barba@hey.com>

docs(research): record topology constraints

b57c9cb

Signed-off-by: Andrew Barba <barba@hey.com>

vercel Bot deployed to Preview – eve-pkg September 1, 2026 04:41 View deployment

vercel Bot deployed to Preview – eve-docs-4759 September 1, 2026 04:42 View deployment

vercel Bot deployed to Preview – eve-docs September 1, 2026 04:43 View deployment

docs(research): conclude low-risk performance trials

876bc70

Signed-off-by: Andrew Barba <barba@hey.com>

AndrewBarba changed the title ~~chore(eve): performance - track latency and overlap turn attributes~~ Sep 1, 2026

vercel Bot deployed to Preview – eve-pkg September 1, 2026 04:46 View deployment

vercel Bot deployed to Preview – eve-docs-4759 September 1, 2026 04:48 View deployment

vercel Bot deployed to Preview – eve-docs September 1, 2026 04:48 View deployment

refactor(eve): split workflow finalization

02c49e2

Signed-off-by: Andrew Barba <barba@hey.com>

vercel Bot temporarily deployed to Preview – eve-pkg September 1, 2026 04:54 Inactive

docs(eve): clarify workflow result contract

d0ccdf6

Signed-off-by: Andrew Barba <barba@hey.com>

vercel Bot deployed to Preview – eve-docs-4759 September 1, 2026 04:55 View deployment

vercel Bot temporarily deployed to Preview – eve-pkg September 1, 2026 04:56 Inactive

vercel Bot deployed to Preview – eve-docs-4759 September 1, 2026 04:57 View deployment

vercel Bot deployed to Preview – eve-docs September 1, 2026 04:57 View deployment

AndrewBarba requested review from ctgowrie and ruiconti September 1, 2026 12:44

ctgowrie approved these changes Sep 1, 2026

View reviewed changes

Merge branch 'main' into barba/turn-performance-tracking

8560aa9

vercel Bot deployed to Preview – eve-pkg September 1, 2026 12:53 View deployment

vercel Bot deployed to Preview – eve-docs-4759 September 1, 2026 12:54 View deployment

vercel Bot deployed to Preview – eve-docs September 1, 2026 12:55 View deployment

AndrewBarba merged commit 6a8340f into main Sep 1, 2026
117 checks passed

AndrewBarba deleted the barba/turn-performance-tracking branch September 1, 2026 13:01

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chore(eve): performance - measure turns and remove root overhead - #2814

chore(eve): performance - measure turns and remove root overhead#2814
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barba/turn-performance-tracking

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Summary

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Low-risk await audit

Validation

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

Delta vs main (e09c721)

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

Delta vs `main (e09c721)`

`eve init` install

`eve init` install details

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