fix(eve): fix Vercel Sandbox file reads

[remiconnesson]

Summary

• adapt Vercel Sandbox's Node file stream to Eve's ReadableStream<Uint8Array> contract
• correct Eve's vendored Vercel Sandbox declaration to match the provider SDK
• add a regression test that consumes the returned stream through Eve's public SandboxSession.readFile() API

Root cause

Vercel Sandbox returns a Node.js readable stream from readFile(). Eve's vendored declaration described that value as a Web ReadableStream, and the Vercel backend passed it through unchanged.

Consumers therefore received a value without getReader(). Download helpers mapped that resulting TypeError to a generic unreadable-file error even though the file existed and was readable inside the sandbox.

User impact

Vercel-backed Eve agents can stream existing sandbox files through SandboxSession.readFile(), including bounded download flows.

Fixes #120.

Verification

• regression test failed before the fix because the returned value was not a ReadableStream
• 3,631 unit tests pass, including the 700-line structural guard
• Eve typecheck, formatting, and lint pass

Also tried the same kind of change locally here, and it worked

[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 19, 2026 9:09pm

[github-actions]

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

Key takeaways

• No notable deltas vs main (bfc7191).

Delta vs main (bfc7191)

Area	Metric	Baseline	Current	Delta
Package	Packed tarball	3.23 MB	3.23 MB	-114 B ✅
Package	Unpacked publish size	11.58 MB	11.58 MB	+61 B ⚠️
Package	Installed footprint	51.79 MB	51.79 MB	+61 B ⚠️
Package	Published files	2163	2163	0
Package	Installed files	5368	5368	0
Runtime	Unique function payloads	2	2	0
Runtime	Total function bytes	9.34 MB	9.34 MB	-12 B ✅
Runtime	Public routes	9	9	0

Changed function payloads vs main (bfc7191) (2)

Function	Status	Baseline	Current	Delta	Route changes
functions/__server.func	changed	3.86 MB	3.86 MB	-62 B ✅	none
functions/.well-known/workflow/v1/flow.func	changed	5.47 MB	5.47 MB	+50 B ⚠️	none

Build Metadata

• Preset: vercel
• Nitro: nitro@3.0.260610-beta
• Output directory: apps/fixtures/weather-agent/.vercel/output
• Build metadata timestamp: 2026-06-19T21:09:42.633Z
• 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@0.11.7
• Package directory: packages/eve
• Tarball: 3.23 MB (eve-0.11.7.tgz)
• Unpacked payload: 11.58 MB across 2163 published files
• Installed footprint: 51.79 MB across 5368 installed files
• Installed root package: 10.47 MB
• Installed dependencies: 41.32 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: 20.61 MB (39.8%)
• eve: 10.47 MB (20.2%)
• ai: 6.20 MB (12.0%)
• zod: 4.97 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 13.0%
🟡 dist/src/compiled/@workflow/core/runtime.js      [##......................] 775.4 kB 6.7%
🟡 dist/src/compiled/@vercel/sandbox/index.js       [##......................] 632.0 kB 5.5%
🟡 dist/src/compiled/@chat-adapter/slack/index.js   [#.......................] 436.9 kB 3.8%
🟡 dist/src/compiled/_chunks/workflow/attribute-... [#.......................] 370.9 kB 3.2%
🔴 Other published files                            [########################] 7.86 MB 67.9%

Installed footprint breakdown

Installed package size
🔴 @rolldown/binding-linux-x64-gnu [########################] 20.61 MB 39.8%
🔴 eve                             [############............] 10.47 MB 20.2%
🔴 ai                              [#######.................] 6.20 MB 12.0%
🟠 zod                             [######..................] 4.97 MB 9.6%
🟠 nitro                           [###.....................] 2.41 MB 4.6%
🟡 rolldown                        [#.......................] 771.0 kB 1.5%
🔴 Other installed packages        [#######.................] 6.37 MB 12.3%

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     [########################] 5.47 MB 58.6%
🔴 functions/__server.func                         [#################.......] 3.86 MB 41.4%

Top Function Payloads

🟠 functions/.well-known/workflow/v1/flow.func • 1 public route • 5.47 MB

Metric	Value
Public routes	/.well-known/workflow/v1/flow
Runtime	nodejs24.x
Handler	index.mjs
Payload	5.47 MB
Function files	5.47 MB across 27 files
Traced dependencies	0 B
Signal	🟠 Bundled file __eve_nitro_handler__.mjs is 1.50 MB (27.5%)

🟠 🔎 Dependency Analysis

📦 Bundled files:

Bundled file size
🟠 __eve_nitro_handler__.mjs              [########################] 1.50 MB 27.5%
🟠 _chunks/runtime.mjs                    [###############.........] 958.4 kB 17.5%
🟡 _chunks/sandbox.mjs                    [############............] 766.0 kB 14.0%
🟡 _chunks/attribute-changes-Bi5DLT8S.mjs [########................] 472.2 kB 8.6%
🟡 _chunks/dist-DTchiX0N.mjs              [#######.................] 460.6 kB 8.4%
🟠 Other bundled files                    [#####################...] 1.31 MB 24.0%

🧾 Vercel Config

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

---

🟠 functions/__server.func • 8 public routes, 1 internal alias • 3.86 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	3.86 MB
Function files	3.86 MB across 21 files
Traced dependencies	0 B
Signal	🟠 Bundled file index.mjs is 1.40 MB (36.3%)

🟠 🔎 Dependency Analysis

📦 Bundled files:

Bundled file size
🟠 index.mjs                              [########################] 1.40 MB 36.3%
🟠 _chunks/runtime.mjs                    [###############.........] 875.8 kB 22.7%
🟠 _chunks/sandbox.mjs                    [#############...........] 766.0 kB 19.8%
🟡 _chunks/attribute-changes-Bi5DLT8S.mjs [########................] 448.5 kB 11.6%
⚪ _libs/zod.mjs                          [##......................] 114.2 kB 3.0%
🟡 Other bundled files                    [####....................] 258.8 kB 6.7%

🧾 Vercel Config

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

[remiconnesson]

Vercel readFile() verification (1f3f8cc)

The regression was reproduced before the fix with a Node Readable returned by the Vercel SDK. Eve passed that value through, and the test failed because it was not an instance of ReadableStream—the same condition that makes the starter's bounded reader fail at stream.getReader().

After the fix:

• the provider Node stream is converted at the Vercel adapter boundary
• Eve's public SandboxSession.readFile() returns a Web ReadableStream
• the regression consumes the stream and matches the original bytes
• provider errors are not caught or replaced by the adapter

The real Vercel Sandbox pass also traversed this adapter successfully: 45 bytes matched with SHA-256 cee7126090710957909be4c25dfff28428432d7416752a2baa4d4f4066400557. Sandbox pr117-vercel-mqlb9eu3-038458 was then deleted and lookup confirmed it was absent.

Current branch verification:

• 3,631 unit tests passed
• focused Vercel suite: 38 tests passed
• typecheck, lint, and formatting passed
• vercel.ts remains at the repository's 700-line structural limit

Reproduction: remiconnesson/eve-single-user-agent-starter#18.

[ctgowrie]

Let's see if readFile solves the requirements now to keep surface area small

[remiconnesson]

Follow-up documentation is in #121. It documents the existing readFile() Web-stream contract, reader selection, and frontend rendering for generated images and file downloads. The docs PR targets main separately and should merge after this runtime fix.