fix(eve): resume duplicate Vercel sandbox creates

[ruiconti]

What

• Resume a named Vercel sandbox when Sandbox.create loses a duplicate-name race.
• Preserve non-duplicate create failures. If the follow-up lookup still cannot find the sandbox, the original create error stays visible.
• Add a regression test for two concurrent first opens of the same Vercel sandbox session.

Failure mode

The incident shape was a load_skill failure after Vercel returned 400 bad_request from sandbox create: the named sandbox already existed, and Vercel told the caller to use GET /sandboxes/:name to resume it.

That can happen because eve names Vercel sandbox sessions deterministically from the backend, deployment scope, runtime session, and graph node. A concurrent first open, or a retried step after the sandbox was created but before eve persisted sandbox metadata, can leave one execution context creating the sandbox while another still sees no session metadata. The losing create got treated as fatal even though the sandbox now existed.

Impact

The Vercel backend now treats that duplicate create as a resumable open. It re-reads the named sandbox and adopts it, while keeping the old error behavior for unrelated create failures.

This lives in the backend rather than load_skill because load_skill only exposed the race. ensureSandboxAccess already dedupes within one provider instance. This handles the cross-provider, workflow retry, and serverless execution cases where process-local state is not enough.

Template-less resumed sessions still run the base runtime setup path, so a caller that adopts the sandbox does not skip the readiness work that a winning create would have done.

Checked locally with the Vercel sandbox unit file, eve typecheck, targeted lint, and git diff --check.

[vercel]

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

Project	Deployment	Actions	Updated (UTC)
eve-docs	Ready	Preview, Comment, Open in v0	Jun 28, 2026 9:08pm

[github-actions]

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

Key takeaways

• No notable deltas vs main (6dc84fc).

Delta vs main (6dc84fc)

Area	Metric	Baseline	Current	Delta
Package	Packed tarball	3.48 MB	3.48 MB	+248 B ⚠️
Package	Unpacked publish size	12.64 MB	12.64 MB	+1.2 kB ⚠️
Package	Installed footprint	52.64 MB	52.64 MB	+1.2 kB ⚠️
Package	Published files	2371	2371	0
Package	Installed files	5579	5579	0
Runtime	Unique function payloads	2	2	0
Runtime	Total function bytes	9.18 MB	9.18 MB	+2.4 kB ⚠️
Runtime	Public routes	9	9	0

Changed function payloads vs main (6dc84fc) (2)

Function	Status	Baseline	Current	Delta	Route changes
functions/.well-known/workflow/v1/flow.func	changed	5.72 MB	5.72 MB	+1.3 kB ⚠️	none
functions/__server.func	changed	3.46 MB	3.46 MB	+1.1 kB ⚠️	none

Build Metadata

• Preset: vercel
• Nitro: nitro@3.0.260610-beta
• Output directory: apps/fixtures/weather-agent/.vercel/output
• Build metadata timestamp: 2026-06-28T21:08:57.226Z
• Route aliases: 9 public, 1 internal (10 total aliases)
• Vercel routes in config: 10
• Severity legend: 🔴 dominant/large, 🟠 notable, 🟡 watch, ⚪ small

Package Drill-Down

Package Details

• Package: eve@0.16.2
• Package directory: packages/eve
• Tarball: 3.48 MB (eve-0.16.2.tgz)
• Unpacked payload: 12.64 MB across 2371 published files
• Installed footprint: 52.64 MB across 5579 installed files
• Installed root package: 11.37 MB
• Installed dependencies: 41.27 MB
• Runtime dependencies: 1
• Peer dependencies: 12 (11 optional)

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

Heavy installed dependencies

• @rolldown/binding-linux-x64-gnu: 20.26 MB (38.5%)
• eve: 11.37 MB (21.6%)
• ai: 6.27 MB (11.9%)
• zod: 5.04 MB (9.6%)
• nitro: 2.41 MB (4.6%)

Publish payload breakdown

Published file size
🟠 dist/src/compiled/experimental-ai-sdk-code-mo... [####....................] 1.51 MB 11.9%
🟡 dist/src/compiled/@workflow/core/runtime.js      [##......................] 788.4 kB 6.2%
🟡 dist/src/compiled/@vercel/sandbox/index.js       [##......................] 632.0 kB 5.0%
🟡 dist/src/compiled/@chat-adapter/slack/index.js   [#.......................] 438.4 kB 3.5%
🟡 dist/src/compiled/_chunks/workflow/attribute-... [#.......................] 371.6 kB 2.9%
🔴 Other published files                            [########################] 8.91 MB 70.4%

Installed footprint breakdown

Installed package size
🔴 @rolldown/binding-linux-x64-gnu [########################] 20.26 MB 38.5%
🔴 eve                             [#############...........] 11.37 MB 21.6%
🔴 ai                              [#######.................] 6.27 MB 11.9%
🔴 zod                             [######..................] 5.04 MB 9.6%
🟠 nitro                           [###.....................] 2.41 MB 4.6%
🟡 rolldown                        [#.......................] 771.7 kB 1.5%
🔴 Other installed packages        [########................] 6.52 MB 12.4%

Runtime dependencies (1)

Package	Range	Notes
nitro	3.0.260610-beta

Peer dependencies (12)

Package	Range	Notes
@opentelemetry/api	^1.0.0	optional peer
@sveltejs/kit	^2.0.0	optional peer
ai	catalog:
braintrust	^3.0.0	optional peer
just-bash	^3.0.0	optional peer
microsandbox	^0.5.0	optional peer
next	^16.0.0	optional peer
nuxt	^4.0.0	optional peer
react	^19.0.0	optional peer
svelte	^5.0.0	optional peer
vite	^8.0.0	optional peer
vue	^3.5.0	optional peer

Function Drill-Down

Payload Size Graph

Unique function payload size and share of total
🔴 functions/.well-known/workflow/v1/flow.func     [########################] 5.72 MB 62.3%
🟠 functions/__server.func                         [###############.........] 3.46 MB 37.7%

Top Function Payloads

🟠 functions/.well-known/workflow/v1/flow.func • 1 public route • 5.72 MB

Metric	Value
Public routes	/.well-known/workflow/v1/flow
Runtime	nodejs24.x
Handler	index.mjs
Payload	5.72 MB
Function files	5.72 MB across 26 files
Traced dependencies	0 B
Signal	🟠 Bundled file __eve_nitro_handler__.mjs is 1.96 MB (34.2%)

🟠 🔎 Dependency Analysis

📦 Bundled files:

Bundled file size
🟠 __eve_nitro_handler__.mjs              [########################] 1.96 MB 34.2%
🟠 _chunks/runtime.mjs                    [############............] 975.4 kB 17.0%
🟡 _chunks/sandbox.mjs                    [#########...............] 766.0 kB 13.4%
🟡 _chunks/attribute-changes-DUxG-Gic.mjs [######..................] 473.2 kB 8.3%
🟡 _libs/@ai-sdk/gateway+[...].mjs        [#####...................] 413.5 kB 7.2%
🟠 Other bundled files                    [##############..........] 1.14 MB 19.9%

🧾 Vercel Config

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

---

🟠 functions/__server.func • 8 public routes, 1 internal alias • 3.46 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]/stream
Internal aliases	/__server
Runtime	nodejs24.x
Handler	index.mjs
Payload	3.46 MB
Function files	3.46 MB across 19 files
Traced dependencies	0 B
Signal	🟠 Bundled file index.mjs is 992.0 kB (28.7%)

🟠 🔎 Dependency Analysis

📦 Bundled files:

Bundled file size
🟠 index.mjs                              [########################] 992.0 kB 28.7%
🟠 _chunks/runtime.mjs                    [#####################...] 883.8 kB 25.5%
🟠 _chunks/sandbox.mjs                    [###################.....] 766.0 kB 22.1%
🟡 _chunks/attribute-changes-DUxG-Gic.mjs [###########.............] 448.9 kB 13.0%
⚪ _libs/zod.mjs                          [###.....................] 114.2 kB 3.3%
🟡 Other bundled files                    [######..................] 255.4 kB 7.4%

🧾 Vercel Config

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