fix(eve): download unresolved attachment links in eve, not the provider

[AndrewBarba]

Summary

When a channel's fetchFile returned null, or the channel had none, eve kept the link in history for the model provider to fetch. A private, expired, or sign-in-gated link then failed every later model call. A Google Drive file shared in a Slack thread broke every later mention in that thread with a 401 (#855). eve now downloads these links itself. It fetches public https: links with the existing SSRF-safe request, the 25 MB default upload cap, and a 30-second timeout. It downloads at most 10 links per message, one at a time, so one request can't make the server buffer an unbounded amount of data. Any other scheme, an HTTP error, a sign-in page, or a refused address becomes a note. A provider reference, such as { openai: "file-…" }, still passes through. Sessions that already hold an unresolved link or eve-url: marker recover, because each one renders as a note at the model call.

This changes what null means in the documented fetchFile contract, so the changeset is minor. A Slack-specific filter for external files lands later in this stack.

Related to #855. Part of the stack from the research plan in #4625.

Validation

• New integration tests in attachment-staging.integration.test.ts cover a downloaded link, refused links, the per-message download limit and serialization, a provider reference, and recovered history. They mock requestPublicUrl, so they make no network calls.
• pnpm --filter eve exec vitest run --config vitest.unit.config.ts: all pass after I deleted a unit test that pinned the old passthrough behavior, which also made a real network request.
• pnpm --filter eve exec vitest run --config vitest.integration.config.ts src/public src/harness src/execution src/channel: 966 passed. One test in entry-handoff-lifetime.integration.test.ts failed under load, then passed when run alone.
• pnpm --filter eve run typecheck, pnpm lint, pnpm fmt, pnpm guard:invariants, and pnpm docs:check pass.

Checklist

• I added tests and documentation where relevant
• I added a changeset if this touches the published eve package
• DCO sign-off passes for every commit (git commit --signoff)

[vercel]

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

Project	Deployment	Actions	Updated
eve-docs	Ready	Preview, v0	Oct 10, 2026 4:57pm UTC
eve-pkg	Ready	Preview, v0	Oct 10, 2026 4:57pm UTC

[github-actions]

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

Key takeaways

• No notable deltas vs barba/attachments-never-unresolved (6f4a055).

Delta vs barba/attachments-never-unresolved (6f4a055)

Area	Metric	Baseline	Current	Delta
Package	Packed tarball	7.58 MB	7.58 MB	+915 B ⚠️
Package	Unpacked publish size	26.69 MB	26.69 MB	+4.4 kB ⚠️
Package	Installed footprint	74.49 MB	74.49 MB	+4.4 kB ⚠️
Package	Published files	4113	4115	+2
Package	Installed files	8118	8120	+2
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	20.38 MB	20.39 MB	+7.2 kB ⚠️
Runtime	Public routes	18	18	0

Changed function payloads vs barba/attachments-never-unresolved (6f4a055) (2)

Function	Status	Baseline	Current	Delta	Route changes
functions/__server.func	changed	10.19 MB	10.19 MB	+3.6 kB ⚠️	none
functions/.well-known/workflow/v1/flow.func	changed	10.19 MB	10.19 MB	+3.6 kB ⚠️	none

eve init install

Metric	Baseline	Current	Delta
Installed footprint	112.79 MB	112.79 MB	+4.4 kB ⚠️
Installed packages	97	97	0
dependencies	4	4	0
devDependencies	2	2	0
Dependency package bytes	44.77 MB	44.78 MB	+4.4 kB ⚠️
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: 2026-10-10T16:58:04.062Z
• 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@0.76.2
• Package directory: packages/eve
• Tarball: 7.58 MB (eve-0.76.2.tgz)
• Unpacked payload: 26.69 MB across 4115 published files
• Installed footprint: 74.49 MB across 8120 installed files
• Installed root package: 26.69 MB
• Installed dependencies: 47.80 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: 26.69 MB (35.8%)
• @rolldown/binding-linux-x64-gnu: 19.62 MB (26.3%)
• ai: 8.14 MB (10.9%)
• zod: 6.14 MB (8.2%)
• undici: 3.56 MB (4.8%)

Publish payload breakdown

Published file size
🟠 dist/src/compiled/shadcn-registry/index.js       [#####...................] 3.85 MB 14.4%
🟠 dist/src/compiled/@photon-ai/chat-adapter-ime... [###.....................] 2.29 MB 8.6%
🟠 dist/src/compiled/@ai-sdk/code-mode/index.js     [#.......................] 1.03 MB 3.8%
🟡 dist/src/compiled/@vercel/blob/index.js          [#.......................] 604.9 kB 2.3%
🟡 dist/src/compiled/_chunks/workflow/undici-D-I... [#.......................] 521.9 kB 2.0%
🔴 Other published files                            [########################] 18.40 MB 68.9%

Installed footprint breakdown

Installed package size
🔴 eve                             [########################] 26.69 MB 35.8%
🔴 @rolldown/binding-linux-x64-gnu [##################......] 19.62 MB 26.3%
🔴 ai                              [#######.................] 8.14 MB 10.9%
🔴 zod                             [######..................] 6.14 MB 8.2%
🟠 undici                          [###.....................] 3.56 MB 4.8%
🟠 nitro                           [##......................] 1.89 MB 2.5%
🔴 Other installed packages        [########................] 8.44 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	^4.41.0	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: 112.79 MB across 10015 installed files
• Installed packages: 97 total (91 transitive-only)
• dependencies: 4 direct packages totaling 44.78 MB
• devDependencies: 2 direct packages totaling 5.11 MB
• Other transitive package files: 62.90 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 (24.8%)
• eve: 26.69 MB (23.7%)
• @rolldown/binding-linux-x64-gnu: 19.62 MB (17.4%)
• zod: 9.76 MB (8.6%)
• ai: 8.14 MB (7.2%)

Installed footprint breakdown

Installed package size
🔴 @typescript/typescript-linux-x64 [########################] 27.95 MB 24.8%
🔴 eve                              [#######################.] 26.69 MB 23.7%
🔴 @rolldown/binding-linux-x64-gnu  [#################.......] 19.62 MB 17.4%
🔴 zod                              [########................] 9.76 MB 8.6%
🔴 ai                               [#######.................] 8.14 MB 7.2%
🟠 undici                           [###.....................] 3.56 MB 3.2%
🔴 Other installed packages         [###############.........] 17.07 MB 15.1%

dependencies (4)

Package	Range	Installed size	Share
@vercel/connect	2.2.0	188.7 kB	0.2%
ai	^7.0.128	8.14 MB	7.2%
eve	file:eve-0.76.2.tgz	26.69 MB	23.7%
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     [########################] 10.19 MB 50.0%
🔴 functions/__server.func                         [########################] 10.19 MB 50.0%

Top Function Payloads

🟠 functions/.well-known/workflow/v1/flow.func • 1 public route • 10.19 MB

Metric	Value
Public routes	/.well-known/workflow/v1/flow
Runtime	nodejs24.x
Handler	index.mjs
Payload	10.19 MB
Function files	10.19 MB across 117 files
Traced dependencies	0 B
Signal	🟠 Bundled file _chunks/vercel.web.mjs is 2.25 MB (22.1%)

🟠 🔎 Dependency Analysis

📦 Bundled files:

Bundled file size
🟠 _chunks/vercel.web.mjs                         [############............] 2.25 MB 22.1%
🟠 _libs/undici.mjs                               [#####...................] 1.01 MB 9.9%
🟡 _chunks/sandbox3.mjs                           [####....................] 815.4 kB 8.0%
🟡 _chunks/compiled-artifacts-instrumentation.mjs [####....................] 757.3 kB 7.4%
🟡 _chunks/token-util-Bla5Z0G9.mjs                [####....................] 704.7 kB 6.9%
🔴 Other bundled files                            [########################] 4.66 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 • 10.19 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	10.19 MB
Function files	10.19 MB across 117 files
Traced dependencies	0 B
Signal	🟠 Bundled file _chunks/vercel.web.mjs is 2.25 MB (22.1%)

🟠 🔎 Dependency Analysis

📦 Bundled files:

Bundled file size
🟠 _chunks/vercel.web.mjs                         [############............] 2.25 MB 22.1%
🟠 _libs/undici.mjs                               [#####...................] 1.01 MB 9.9%
🟡 _chunks/sandbox3.mjs                           [####....................] 815.4 kB 8.0%
🟡 _chunks/compiled-artifacts-instrumentation.mjs [####....................] 757.3 kB 7.4%
🟡 _chunks/token-util-Bla5Z0G9.mjs                [####....................] 704.7 kB 6.9%
🔴 Other bundled files                            [########################] 4.66 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: 3.35 s -> 3.33 s (-20.5 ms) vs barba/attachments-never-unresolved (6f4a055).
• Timing is informational: shared GitHub runners are too variable for a hard timing budget.

Detailed phase timings vs `barba/attachments-never-unresolved (6f4a055)`

Phase	Baseline	Current	Delta
extension.check	21.7 ms	18.3 ms	-3.4 ms
project.resolve	0.4 ms	0.4 ms	0.0 ms
workspace.create	0.6 ms	0.5 ms	-0.1 ms
host.prepare	689.8 ms	750.6 ms	+60.8 ms
vercel.service-prefix.resolve	1.5 ms	1.4 ms	-0.1 ms
nitro.create	590.1 ms	576.5 ms	-13.6 ms
sandbox.prewarm	204.9 ms	196.6 ms	-8.3 ms
nitro.cache.prepare	0.3 ms	0.2 ms	-0.1 ms
nitro.prepare	0.7 ms	0.7 ms	0.0 ms
nitro.public-assets	0.7 ms	0.7 ms	0.0 ms
nitro.prerender	0.5 ms	0.5 ms	0.0 ms
nitro.bundle	1.66 s	1.62 s	-46.2 ms
nitro.cache.write	0.3 ms	0.3 ms	0.0 ms
vercel.workflow-function.materialize	80.4 ms	77.1 ms	-3.3 ms
agent-summary.emit	0.6 ms	0.6 ms	0.0 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	3.1 ms	3.3 ms	+0.2 ms
workspace.remove	2.3 ms	2.3 ms	0.0 ms

[roboeve]

This ignores the channel's configured uploadPolicy. Inbound checks can't size a link: evaluateFilePart gets null from getKnownByteLength for a URL and lets it through (upload-policy.ts:155-169). So a route with maxBytes: 5MB, or maxBytes: 0, which the docs say rejects every attachment, still downloads and stages up to 25 MiB here.

Media type has the same gap. The allowlist was checked against the caller-declared part.mediaType, and stageResolvedBytes then swaps in the fetched content-type (attachment-staging.ts:523) without checking it again. A link declared as image/png can stage any type.

Before this PR the provider fetched the link and eve never stored the bytes, so the PR opens this gap. Fix: pass the effective policy into staging, use its maxBytes as maxResponseSize (and refuse when uploads are disabled), and run isMediaTypeAllowed on the resolved media type before writing.

[roboeve]

This fallback now runs for every unclaimed link, and stageAttachmentsForAdapter calls it through an unbounded Promise.all over all file parts (lines 75-81). eveChannel accepts any number of file parts whose data is a URL string (eve-channel/request.ts:438-445), and each download can buffer up to 25 MiB. So a small request listing a few hundred links starts that many 25 MiB downloads at once in one step: memory and sockets blow up from a request of a few KB. Before this PR those links went to the provider untouched. Cap the number of attachments, or the total bytes per message, and/or limit how many links resolve at the same time.

[roboeve]

isUnresolvedFileData repeats readFileData's switch, and the two copies already disagree. readFileData treats { type: "url", url: "data:..." } as bytes (line 51-53 recurses), while this branch calls every tagged url unresolved, so replaceUnresolvedFileParts would swap valid inline content for a "could not be retrieved" note. The reverse also happens: line 72 treats any data: string as resolved, but readFileData reads a malformed one as unreadable, so it still reaches the provider. Both directions are rare today, but keeping two parallel classifiers in sync by hand will drift further. Suggest one classifier that never decodes (bytes / link / reference / unreadable) shared by both functions, with readFileData adding the decode step on top.

[roboeve]

eve's own download failures get kind resolver-threw plus the channel's adapterKind. They then reach the "attachment resolver failed" warning at attachment-staging.ts:502, and EveAttachmentError is documented as "a channel's fetchFile fails" (errors.ts:24-26). In operator logs, a 404 from a public link looks like a bug in the Slack or Telegram resolver. A separate kind (e.g. download-failed) or an adapterKind like "eve" would keep the two sources apart.

[vercel]

Additional Suggestion:

stageAttachmentsForAdapter resolves every file part through an unbounded Promise.all, so a message listing many URL attachments fans out that many concurrent ~25 MiB downloads, exhausting memory and sockets.

[vercel]

eve's public-link attachment download hardcodes the 25 MiB default cap and never re-checks the resolved content-type, so a route's configured uploadPolicy (maxBytes, maxBytes: 0, or allowedMediaTypes) is bypassed for link attachments.

[AndrewBarba]

Collapsed into #4635.