test(eve): repro dev forward reusing a worker socket closed on keep-alive timeout by roboeve[bot] · Pull Request #5003 · vercel/eve

roboeve · 2026-10-17T23:00:27Z

Repro for #5001: eve dev answers 503 when the parent forwards a request on a pooled worker socket that the worker already closed. The fix arrives as a stacked PR.

Why

The dev server forwards each request to the dev worker through env-runner's proxyFetch, which uses a shared keep-alive http.Agent with no idle timeout. The worker's HTTP server closes idle sockets after 6s (Node 24's 5s keepAliveTimeout plus its 1s buffer). Node only uses the server's Keep-Alive: timeout=5 hint to shorten an agent timeout that is already set, so this agent never expires idle sockets itself (freeSocket.timeout === 0). The parent learns a pooled socket is dead only when its event loop reads the worker's FIN. If it dispatches a forward before that, the request goes out on a closed socket, the forward throws, and writeRequestError answers 503. CPU load delays the parent's event loop, which widens that window.

Repro

The new scenario test boots a real DrainedNitroDevServer with the real Node dev worker, sends one request to fill the pool, then blocks the parent for 7s inside the control handler (no event-loop turn, like CPU starvation) before the next forward.

Before the it.fails marker, on main (f4e8ef14f, Node 24, Linux):

pnpm --filter eve exec vitest run --config vitest.scenario.config.ts \
  src/internal/nitro/host/drained-nitro-dev-server.scenario.test.ts -t "keep-alive"

 × forwards a request after the parent stalls past the worker keep-alive timeout 7176ms
- Expected
+ Received
  {
-   "body": "worker",
-   "status": 200,
+   "body": "{\"error\":\"socket hang up\"}",
+   "status": 503,
  }

It failed 4 of 4 runs. Controls with a 1s and a 5.5s stall pass, so the failure tracks the worker's keep-alive deadline. Linux reports the reset as socket hang up (ECONNRESET); the reporter's macOS shows read ECONNRESET. Both come from the same failed forward.

With the marker: Tests 15 passed | 1 expected fail (16).

Regressed in: not a recent regression. The same test fails with the same 503 on eve@0.79.0 and eve@0.50.0, and env-runner@0.1.16 / httpxy@0.5.5 have been pinned since at least eve@0.29.5.

…live timeout Pins #5001 as an expected failure. Co-authored-by: ruiconti <1834568+ruiconti@users.noreply.github.com>

vercel · 2026-10-17T23:00:33Z

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Project	Deployment	Actions	Updated
eve-docs	Ready	Preview, v0	Oct 17, 2026 11:01pm UTC
eve-pkg	Ready	Preview, v0	Oct 17, 2026 11:01pm UTC

github-actions · 2026-10-17T23:03:56Z

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

Key takeaways

No notable deltas vs main (f4e8ef1).

Delta vs `main (f4e8ef1)`

Area	Metric	Baseline	Current	Delta
Package	Packed tarball	7.66 MB	7.66 MB	+66 B ⚠️
Package	Unpacked publish size	26.97 MB	26.97 MB	0 B ➖
Package	Installed footprint	75.11 MB	75.11 MB	0 B ➖
Package	Published files	4171	4171	0
Package	Installed files	8182	8182	0
Package	Installed package instances	34	34	0
Package	Distinct installed package names	32	32	0
Package	Installed dependency edges	51	51	0
Package	Installed optional peer edges	9	9	0
Runtime	Unique function payloads	2	2	0
Runtime	Total function bytes	20.77 MB	20.77 MB	-120 B ✅
Runtime	Public routes	18	18	0

Changed function payloads vs main (f4e8ef1) (2)

Function	Status	Baseline	Current	Delta	Route changes
`functions/__server.func`	changed	10.38 MB	10.38 MB	-60 B ✅	none
`functions/.well-known/workflow/v1/flow.func`	changed	10.38 MB	10.38 MB	-60 B ✅	none

`eve init` install

Metric	Baseline	Current	Delta
Installed footprint	113.50 MB	113.50 MB	0 B ➖
Installed packages	97	97	0
dependencies	4	4	0
devDependencies	2	2	0
Dependency package bytes	45.25 MB	45.25 MB	0 B ➖
devDependency package bytes	5.11 MB	5.11 MB	0 B ➖

Build Metadata

Preset: vercel
Nitro: nitro@3.0.260903-beta
Output directory: apps/fixtures/weather-agent/.vercel/output
Build metadata timestamp: 2026-10-17T23:03:06.793Z
Route aliases: 18 public, 1 internal (19 total aliases)
Vercel routes in config: 21
Severity legend: 🔴 dominant/large, 🟠 notable, 🟡 watch, ⚪ small

Package Drill-Down

Package Details

Package: eve@0.80.1
Package directory: packages/eve
Tarball: 7.66 MB (eve-0.80.1.tgz)
Unpacked payload: 26.97 MB across 4171 published files
Installed footprint: 75.11 MB across 8182 installed files
Installed root package: 26.97 MB
Installed dependencies: 48.14 MB
Installed package instances: 34
Distinct installed package names: 32
Installed dependency edges: 51
Installed optional peer edges: 9
Runtime dependencies: 2
Peer dependencies: 7 (6 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: 26.97 MB (35.9%)
@rolldown/binding-linux-x64-gnu: 19.81 MB (26.4%)
ai: 8.24 MB (11.0%)
zod: 6.15 MB (8.2%)
undici: 3.58 MB (4.8%)

Publish payload breakdown

Published file size
🟠 dist/src/compiled/shadcn-registry/index.js       [#####...................] 3.85 MB 14.3%
🟠 dist/src/compiled/@photon-ai/chat-adapter-ime... [###.....................] 2.29 MB 8.5%
🟠 dist/src/compiled/@ai-sdk/code-mode/index.js     [#.......................] 1.03 MB 3.8%
🟡 dist/src/compiled/@vercel/blob/index.js          [#.......................] 604.9 kB 2.2%
🟡 dist/src/compiled/_chunks/workflow/undici-D-I... [#.......................] 521.9 kB 1.9%
🔴 Other published files                            [########################] 18.68 MB 69.3%

Installed footprint breakdown

Installed package size
🔴 eve                             [########################] 26.97 MB 35.9%
🔴 @rolldown/binding-linux-x64-gnu [##################......] 19.81 MB 26.4%
🔴 ai                              [#######.................] 8.24 MB 11.0%
🔴 zod                             [#####...................] 6.15 MB 8.2%
🟠 undici                          [###.....................] 3.58 MB 4.8%
🟠 nitro                           [##......................] 1.89 MB 2.5%
🔴 Other installed packages        [########................] 8.46 MB 11.3%

Runtime dependencies (2)

Package	Range	Notes
`nitro`	`3.0.260903-beta`
`undici`	`8.10.2`

Peer dependencies (7)

Package	Range	Notes
`@opentelemetry/api`	`^1.0.0`	optional peer
`ai`	`catalog:`
`braintrust`	`^3.0.0`	optional peer
`chat`	`^4.42.0`	optional peer
`dd-trace`	`^6.13.0`	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: 113.50 MB across 10099 installed files
Installed packages: 97 total (91 transitive-only)
dependencies: 4 direct packages totaling 45.25 MB
devDependencies: 2 direct packages totaling 5.11 MB
Other transitive package files: 63.14 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 (24.6%)
eve: 26.97 MB (23.8%)
@rolldown/binding-linux-x64-gnu: 19.81 MB (17.5%)
zod: 9.76 MB (8.6%)
ai: 8.24 MB (7.3%)

Installed footprint breakdown

Installed package size
🔴 @typescript/typescript-linux-x64 [########################] 27.95 MB 24.6%
🔴 eve                              [#######################.] 26.97 MB 23.8%
🔴 @rolldown/binding-linux-x64-gnu  [#################.......] 19.81 MB 17.5%
🔴 zod                              [########................] 9.76 MB 8.6%
🔴 ai                               [#######.................] 8.24 MB 7.3%
🟠 undici                           [###.....................] 3.58 MB 3.1%
🔴 Other installed packages         [###############.........] 17.19 MB 15.1%

dependencies (4)

Package	Range	Installed size	Share
`@vercel/connect`	`2.5.2`	276.3 kB	0.2%
`ai`	`^7.0.137`	8.24 MB	7.3%
`eve`	`file:eve-0.80.1.tgz`	26.97 MB	23.8%
`zod`	`4.5.4`	9.76 MB	8.6%

devDependencies (2)

Package	Range	Installed size	Share
`@types/node`	`24.x`	2.61 MB	2.3%
`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     [########################] 10.38 MB 50.0%
🔴 functions/__server.func                         [########################] 10.38 MB 50.0%

Top Function Payloads

🟠 functions/.well-known/workflow/v1/flow.func • 1 public route • 10.38 MB

Metric	Value
Public routes	`/.well-known/workflow/v1/flow`
Runtime	`nodejs24.x`
Handler	`index.mjs`
Payload	10.38 MB
Function files	10.38 MB across 122 files
Traced dependencies	0 B
Signal	🟠 Bundled file `_chunks/vercel.web.mjs` is 2.38 MB (22.9%)

🟠 🔎 Dependency Analysis

📦 Bundled files:

Bundled file size
🟠 _chunks/vercel.web.mjs                         [############............] 2.38 MB 22.9%
🟠 _libs/undici.mjs                               [#####...................] 1.01 MB 9.7%
🟡 _chunks/sandbox3.mjs                           [####....................] 815.4 kB 7.9%
🟡 _chunks/compiled-artifacts-instrumentation.mjs [####....................] 734.8 kB 7.1%
🟡 _chunks/token-util-Bla5Z0G9.mjs                [####....................] 704.7 kB 6.8%
🔴 Other bundled files                            [########################] 4.74 MB 45.7%

🧾 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 • 17 public routes, 1 internal alias • 10.38 MB

Metric	Value
Public routes	`/` `/.well-known/workflow/v1/webhook/[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/session/[sessionId]/stubs` `/eve/v1/task-input/[token]`
Internal aliases	`/__server`
Runtime	`nodejs24.x`
Handler	`index.mjs`
Payload	10.38 MB
Function files	10.38 MB across 122 files
Traced dependencies	0 B
Signal	🟠 Bundled file `_chunks/vercel.web.mjs` is 2.38 MB (22.9%)

🟠 🔎 Dependency Analysis

📦 Bundled files:

Bundled file size
🟠 _chunks/vercel.web.mjs                         [############............] 2.38 MB 22.9%
🟠 _libs/undici.mjs                               [#####...................] 1.01 MB 9.7%
🟡 _chunks/sandbox3.mjs                           [####....................] 815.4 kB 7.9%
🟡 _chunks/compiled-artifacts-instrumentation.mjs [####....................] 734.8 kB 7.1%
🟡 _chunks/token-util-Bla5Z0G9.mjs                [####....................] 704.7 kB 6.8%
🔴 Other bundled files                            [########################] 4.74 MB 45.7%

🧾 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: 3.61 s -> 3.50 s (-110.8 ms) vs main (f4e8ef1).
Timing is informational: shared GitHub runners are too variable for a hard timing budget.

Detailed phase timings vs `main (f4e8ef1)`

Phase	Baseline	Current	Delta
`extension.check`	0.4 ms	0.4 ms	0.0 ms
`project.resolve`	0.3 ms	0.3 ms	0.0 ms
`workspace.create`	0.5 ms	0.6 ms	+0.1 ms
`host.prepare`	822.8 ms	719.2 ms	-103.6 ms
`vercel.service-prefix.resolve`	1.7 ms	1.6 ms	-0.1 ms
`nitro.create`	652.5 ms	632.5 ms	-20.0 ms
`sandbox.prewarm`	347.7 ms	356.7 ms	+9.0 ms
`nitro.cache.prepare`	0.3 ms	0.2 ms	-0.1 ms
`nitro.prepare`	0.7 ms	0.8 ms	+0.1 ms
`nitro.public-assets`	0.8 ms	0.8 ms	0.0 ms
`nitro.prerender`	0.5 ms	0.4 ms	-0.1 ms
`nitro.bundle`	1.66 s	1.66 s	+5.1 ms
`nitro.cache.write`	0.4 ms	0.4 ms	0.0 ms
`vercel.workflow-function.materialize`	46.7 ms	47.7 ms	+1.0 ms
`agent-summary.emit`	0.7 ms	0.6 ms	-0.1 ms
`connect-manifest.emit`	0.3 ms	0.3 ms	0.0 ms
`nitro.close`	0.1 ms	0.1 ms	0.0 ms
`output.publish`	3.3 ms	3.3 ms	0.0 ms
`workspace.remove`	2.5 ms	2.3 ms	-0.2 ms

test(eve): repro dev forward reusing a worker socket closed on keep-a…

ab8cb30

…live timeout Pins #5001 as an expected failure. Co-authored-by: ruiconti <1834568+ruiconti@users.noreply.github.com>

roboeve Bot assigned ruiconti Oct 17, 2026

roboeve Bot requested a review from ruiconti October 17, 2026 23:00

vercel Bot deployed to Preview – eve-docs October 17, 2026 23:01

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vercel Bot deployed to Preview – eve-pkg October 17, 2026 23:01

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roboeve Bot mentioned this pull request Oct 17, 2026

eve dev intermittently answers 503 {"error":"read ECONNRESET"} to channel requests under CPU load #5001

Open

roboeve Bot mentioned this pull request Oct 17, 2026

fix(eve): forward each dev request on a fresh worker connection #5004

Open

roboeve Bot added this pull request to stack #5005 October 17, 2026 23:05

roboeve Bot marked this pull request as ready for review October 17, 2026 23:44

roboeve Bot requested a review from a team as a code owner October 17, 2026 23:44

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test(eve): repro dev forward reusing a worker socket closed on keep-alive timeout - #5003

test(eve): repro dev forward reusing a worker socket closed on keep-alive timeout#5003
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triage/5001-repro

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Package Details

`eve init` install details

Payload Size Graph

Top Function Payloads

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

Delta vs main (f4e8ef1)

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 (f4e8ef1)`

`eve init` install

`eve init` install details

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