fix(eve): restore Bash process substitution in Vercel sandboxes

[vercel-gh-bot-3]

Fixes #2565.

Vercel Sandbox guests expose /proc/self/fd but can omit /dev/fd. Bash parses process substitution in that state, then fails when it opens /dev/fd/N. Read loops can continue with empty input, which turns verification logic into a false success.

Hypothesis

/dev is runtime-owned, so an image-layer change cannot reliably establish this path across snapshots and resumed sessions. If eve validates and repairs /dev/fd during framework setup and every Vercel session attach, Bash process substitution should work before any authored command runs.

Changes

• Validate that /dev/fd resolves to the same descriptor directory as /proc/self/fd
• Create the conventional symlink when it is missing, using the existing sudo retry when required
• Run base-runtime setup for fresh, snapshot-backed, and resumed Vercel sessions
• Preserve the existing network-policy behavior for fresh template-less sessions
• Add lifecycle coverage and a patch changeset

Validation

• pnpm --filter eve exec vitest run --config vitest.unit.config.ts src/execution/sandbox/bindings/vercel.test.ts (48 tests)
• pnpm --filter eve exec vitest run --config vitest.integration.config.ts src/execution/sandbox/bindings/docker.integration.test.ts (22 tests)
• pnpm --filter eve typecheck
• pnpm guard:invariants
• /bin/sh syntax, execution, and descriptor-identity checks
• Sandbox repro on Ubuntu 26.04: main returned n=0 with /dev/fd/63: No such file or directory; the candidate setup returned n=2 and exit code 0

An independent correctness review found no remaining issues after strengthening the descriptor validation.

Requested by: jfonturbel

[vercel]

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Project	Deployment	Actions	Updated (UTC)
eve-docs	Ready	Preview, v0	Aug 25, 2026 7:52pm
eve-docs-4759	Ready	Preview, v0	Aug 25, 2026 7:52pm
eve-pkg	Ready	Preview, v0	Aug 25, 2026 7:52pm

[github-actions]

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

Key takeaways

• No notable deltas vs main (91700b0).

Delta vs main (91700b0)

Area	Metric	Baseline	Current	Delta
Package	Packed tarball	8.22 MB	8.22 MB	+3 B ⚠️
Package	Unpacked publish size	30.99 MB	30.99 MB	+476 B ⚠️
Package	Installed footprint	75.20 MB	75.20 MB	+476 B ⚠️
Package	Published files	3497	3497	0
Package	Installed files	7212	7212	0
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	18.37 MB	18.37 MB	+882 B ⚠️
Runtime	Public routes	16	16	0

Changed function payloads vs main (91700b0) (2)

Function	Status	Baseline	Current	Delta	Route changes
functions/__server.func	changed	9.18 MB	9.19 MB	+441 B ⚠️	none
functions/.well-known/workflow/v1/flow.func	changed	9.18 MB	9.19 MB	+441 B ⚠️	none

eve init install

Metric	Baseline	Current	Delta
Installed footprint	113.64 MB	113.64 MB	+476 B ⚠️
Installed packages	120	120	0
dependencies	4	4	0
devDependencies	2	2	0
Dependency package bytes	45.59 MB	45.59 MB	+476 B ⚠️
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: 2026-08-25T19:54:16.156Z
• Route aliases: 16 public, 1 internal (17 total aliases)
• Vercel routes in config: 19
• Severity legend: 🔴 dominant/large, 🟠 notable, 🟡 watch, ⚪ small

Package Drill-Down

Package Details

• Package: eve@0.44.4
• Package directory: packages/eve
• Tarball: 8.22 MB (eve-0.44.4.tgz)
• Unpacked payload: 30.99 MB across 3497 published files
• Installed footprint: 75.20 MB across 7212 installed files
• Installed root package: 29.64 MB
• Installed dependencies: 45.57 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: 29.64 MB (39.4%)
• @rolldown/binding-linux-x64-gnu: 19.91 MB (26.5%)
• ai: 6.77 MB (9.0%)
• zod: 5.07 MB (6.7%)
• undici: 3.50 MB (4.7%)

Publish payload breakdown

Published file size
🔴 dist/src/compiled/shadcn-registry/index.js       [##############..........] 9.76 MB 31.5%
🟠 dist/src/compiled/@photon-ai/chat-adapter-ime... [####....................] 2.44 MB 7.9%
🟠 dist/src/compiled/experimental-ai-sdk-code-mo... [##......................] 1.51 MB 4.9%
🟡 dist/src/compiled/_chunks/workflow/undici-Dzn... [#.......................] 512.7 kB 1.7%
🟡 dist/src/compiled/_chunks/node/undici-CUIybhQ... [#.......................] 508.8 kB 1.6%
🔴 Other published files                            [########################] 16.26 MB 52.5%

Installed footprint breakdown

Installed package size
🔴 eve                             [########################] 29.64 MB 39.4%
🔴 @rolldown/binding-linux-x64-gnu [################........] 19.91 MB 26.5%
🔴 ai                              [#####...................] 6.77 MB 9.0%
🔴 zod                             [####....................] 5.07 MB 6.7%
🟠 undici                          [###.....................] 3.50 MB 4.7%
🟠 nitro                           [##......................] 2.41 MB 3.2%
🔴 Other installed packages        [######..................] 7.91 MB 10.5%

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: 113.64 MB across 9108 installed files
• Installed packages: 120 total (114 transitive-only)
• dependencies: 4 direct packages totaling 45.59 MB
• devDependencies: 2 direct packages totaling 5.04 MB
• Other transitive package files: 63.01 MB

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

Heavy installed dependencies

• eve: 29.64 MB (26.1%)
• @typescript/typescript-linux-x64: 27.95 MB (24.6%)
• @rolldown/binding-linux-x64-gnu: 19.91 MB (17.5%)
• zod: 9.02 MB (7.9%)
• ai: 6.77 MB (6.0%)

Installed footprint breakdown

Installed package size
🔴 eve                              [########################] 29.64 MB 26.1%
🔴 @typescript/typescript-linux-x64 [#######################.] 27.95 MB 24.6%
🔴 @rolldown/binding-linux-x64-gnu  [################........] 19.91 MB 17.5%
🔴 zod                              [#######.................] 9.02 MB 7.9%
🔴 ai                               [#####...................] 6.77 MB 6.0%
🟠 undici                           [###.....................] 3.50 MB 3.1%
🔴 Other installed packages         [##############..........] 16.85 MB 14.8%

dependencies (4)

Package	Range	Installed size	Share
@vercel/connect	1.0.0	167.9 kB	0.1%
ai	^7.0.58	6.77 MB	6.0%
eve	file:eve-0.44.4.tgz	29.64 MB	26.1%
zod	4.4.3	9.02 MB	7.9%

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     [########################] 9.19 MB 50.0%
🔴 functions/__server.func                         [########################] 9.19 MB 50.0%

Top Function Payloads

🟠 functions/.well-known/workflow/v1/flow.func • 1 public route • 9.19 MB

Metric	Value
Public routes	/.well-known/workflow/v1/flow
Runtime	nodejs24.x
Handler	index.mjs
Payload	9.19 MB
Function files	9.19 MB across 99 files
Traced dependencies	0 B
Signal	🟠 Bundled file index.mjs is 2.03 MB (22.1%)

🟠 🔎 Dependency Analysis

📦 Bundled files:

Bundled file size
🟠 index.mjs                   [############............] 2.03 MB 22.1%
🟡 _libs/undici.mjs            [######..................] 980.5 kB 10.7%
🟡 _chunks/sandbox.mjs         [#####...................] 781.9 kB 8.5%
🟡 _chunks/frames-Dl2Hcma4.mjs [####....................] 678.7 kB 7.4%
🟡 _chunks/chatgpt-model.mjs   [####....................] 666.7 kB 7.3%
🔴 Other bundled files         [########################] 4.05 MB 44.1%

🧾 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 • 15 public routes, 1 internal alias • 9.19 MB

Metric	Value
Public routes	/ /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	9.19 MB
Function files	9.19 MB across 99 files
Traced dependencies	0 B
Signal	🟠 Bundled file index.mjs is 2.03 MB (22.1%)

🟠 🔎 Dependency Analysis

📦 Bundled files:

Bundled file size
🟠 index.mjs                   [############............] 2.03 MB 22.1%
🟡 _libs/undici.mjs            [######..................] 980.5 kB 10.7%
🟡 _chunks/sandbox.mjs         [#####...................] 781.9 kB 8.5%
🟡 _chunks/frames-Dl2Hcma4.mjs [####....................] 678.7 kB 7.4%
🟡 _chunks/chatgpt-model.mjs   [####....................] 666.7 kB 7.3%
🔴 Other bundled files         [########################] 4.05 MB 44.1%

🧾 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: 2.45 s -> 2.40 s (-46.9 ms) vs main (91700b0).
• Timing is informational: shared GitHub runners are too variable for a hard timing budget.

Detailed phase timings vs `main (91700b0)`

Phase	Baseline	Current	Delta
extension.check	1.1 ms	1.1 ms	0.0 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	338.9 ms	323.5 ms	-15.4 ms
vercel.service-prefix.resolve	2.2 ms	2.3 ms	+0.1 ms
nitro.create	265.9 ms	266.3 ms	+0.4 ms
sandbox.prewarm	237.1 ms	247.6 ms	+10.5 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	0.8 ms	0.0 ms
nitro.prerender	0.4 ms	0.6 ms	+0.2 ms
nitro.bundle	1.55 s	1.50 s	-42.1 ms
nitro.cache.write	0.4 ms	0.4 ms	0.0 ms
vercel.workflow-function.materialize	45.2 ms	45.2 ms	0.0 ms
agent-summary.emit	0.7 ms	0.7 ms	0.0 ms
nitro.close	0.1 ms	0.1 ms	0.0 ms
output.publish	3.6 ms	3.4 ms	-0.2 ms
workspace.remove	2.3 ms	2.1 ms	-0.2 ms