feat(eve): a2a - implement client and channel support by AndrewBarba · Pull Request #3487 · vercel/eve

AndrewBarba · 2026-09-17T20:56:20Z

Summary

Agents built outside eve need a supported way to delegate work to eve and receive work from it. This adds A2A 1.0 JSON-RPC in both directions: defineA2AAgent runs external agents as durable static or dynamic subagents, and a2aChannel exposes public discovery plus authenticated task operations and SSE. Both reuse eve’s authorization and task lifecycle, including input continuation and cancellation. Native defineRemoteAgent behavior is preserved, and the official A2A SDK is a development dependency only.

Closes #678. Implements the proposal in #2887; overlaps the alternative approaches in #3373 and #3215.

The v1 channel uses one context per task and streams durable snapshots and completed artifacts. General task listing scans up to 1,000 retained workflow records, with direct contextId lookup beyond that bound. Other protocol bindings, push notifications, signed cards, and extended cards remain outside this release. Existing extension contracts are retained with new epochs, documentation, and a patch changeset.

Validation

pnpm test:unit — 8,902 tests passed, one skipped after rebasing onto current main.
pnpm test:integration — 893 tests passed before the rebase.
pnpm --filter eve exec vitest run --config vitest.scenario.config.ts src/internal/a2a/a2a.scenario.test.ts — official SDK discovery, task completion, input continuation, cancellation, SSE, pagination, and authenticated static/dynamic eve-to-eve delegation passed.
pnpm --filter eve exec vitest run --config vitest.scenario.config.ts src/internal/invocation/mcp-agent-channel.scenario.test.ts — existing MCP channel scenario passed.
pnpm typecheck, pnpm lint, pnpm fmt, pnpm docs:check, pnpm check:deps, pnpm guard:invariants, and pnpm update:extension-contracts passed. Lint reports existing warnings in unrelated files.
Added a deterministic A2A lifecycle fixture for CI workflow worlds. E2E evals were not run locally; CI results are pending.

Checklist

This change was requested or approved by a maintainer
I ran the relevant checks from CONTRIBUTING.md
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)

Signed-off-by: Andrew Barba <barba@hey.com>

vercel · 2026-09-17T20:56:22Z

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

Project	Deployment	Actions	Updated
eve-docs	Ready	Preview, v0	Sep 17, 2026 8:57pm UTC
eve-pkg	Ready	Preview, v0	Sep 17, 2026 8:57pm UTC

socket-security · 2026-09-17T20:56:54Z

Review the following changes in direct dependencies. Learn more about Socket for GitHub.

Diff	Package	Supply Chain Security	Vulnerability	Quality	Maintenance	License
	npm/@a2a-js/sdk@1.1.0

View full report

github-actions · 2026-09-17T21:00:19Z

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

Key takeaways

Runtime delta: function payloads 20.26 MB -> 20.61 MB (+351.6 kB ⚠️).

Delta vs `main (1e872e3)`

Area	Metric	Baseline	Current	Delta
Package	Packed tarball	8.72 MB	8.75 MB	+21.2 kB ⚠️
Package	Unpacked publish size	32.63 MB	32.71 MB	+78.9 kB ⚠️
Package	Installed footprint	78.70 MB	78.78 MB	+78.9 kB ⚠️
Package	Published files	4007	4029	+22
Package	Installed files	7967	7989	+22
Package	Installed package instances	33	33	0
Package	Distinct installed package names	32	32	0
Package	Installed dependency edges	51	51	0
Package	Installed optional peer edges	8	8	0
Runtime	Unique function payloads	2	2	0
Runtime	Total function bytes	20.26 MB	20.61 MB	+351.6 kB ⚠️
Runtime	Public routes	18	18	0

Changed function payloads vs main (1e872e3) (2)

Function	Status	Baseline	Current	Delta	Route changes
`functions/__server.func`	changed	10.13 MB	10.31 MB	+175.8 kB ⚠️	none
`functions/.well-known/workflow/v1/flow.func`	changed	10.13 MB	10.31 MB	+175.8 kB ⚠️	none

`eve init` install

Metric	Baseline	Current	Delta
Installed footprint	116.92 MB	117.00 MB	+78.9 kB ⚠️
Installed packages	113	113	0
dependencies	4	4	0
devDependencies	2	2	0
Dependency package bytes	49.33 MB	49.41 MB	+78.9 kB ⚠️
devDependency package bytes	5.04 MB	5.04 MB	0 B ➖

Build Metadata

Preset: vercel
Nitro: nitro@3.0.260903-beta
Output directory: apps/fixtures/weather-agent/.vercel/output
Build metadata timestamp: 2026-09-17T20:59:22.625Z
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@0.59.0
Package directory: packages/eve
Tarball: 8.75 MB (eve-0.59.0.tgz)
Unpacked payload: 32.71 MB across 4029 published files
Installed footprint: 78.78 MB across 7989 installed files
Installed root package: 31.28 MB
Installed dependencies: 47.50 MB
Installed package instances: 33
Distinct installed package names: 32
Installed dependency edges: 51
Installed optional peer edges: 8
Runtime dependencies: 2
Peer dependencies: 6 (5 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: 31.28 MB (39.7%)
@rolldown/binding-linux-x64-gnu: 19.10 MB (24.2%)
ai: 7.56 MB (9.6%)
zod: 6.76 MB (8.6%)
undici: 3.51 MB (4.5%)

Publish payload breakdown

Published file size
🔴 dist/src/compiled/shadcn-registry/index.js       [#############...........] 9.76 MB 29.8%
🟠 dist/src/compiled/@photon-ai/chat-adapter-ime... [###.....................] 2.27 MB 6.9%
🟠 dist/src/compiled/@ai-sdk/code-mode/index.js     [#.......................] 1.03 MB 3.1%
🟡 dist/src/compiled/@vercel/blob/index.js          [#.......................] 901.4 kB 2.8%
🟡 dist/src/compiled/_chunks/workflow/signal-exi... [#.......................] 514.6 kB 1.6%
🔴 Other published files                            [########################] 18.24 MB 55.8%

Installed footprint breakdown

Installed package size
🔴 eve                             [########################] 31.28 MB 39.7%
🔴 @rolldown/binding-linux-x64-gnu [###############.........] 19.10 MB 24.2%
🔴 ai                              [######..................] 7.56 MB 9.6%
🔴 zod                             [#####...................] 6.76 MB 8.6%
🟠 undici                          [###.....................] 3.51 MB 4.5%
🟠 nitro                           [#.......................] 1.89 MB 2.4%
🔴 Other installed packages        [#######.................] 8.67 MB 11.0%

Runtime dependencies (2)

Package	Range	Notes
`nitro`	`3.0.260903-beta`
`undici`	`8.9.0`

Peer dependencies (6)

Package	Range	Notes
`@opentelemetry/api`	`^1.0.0`	optional peer
`ai`	`catalog:`
`braintrust`	`^3.0.0`	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: 117.00 MB across 9883 installed files
Installed packages: 113 total (107 transitive-only)
dependencies: 4 direct packages totaling 49.41 MB
devDependencies: 2 direct packages totaling 5.04 MB
Other transitive package files: 62.55 MB

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

Heavy installed dependencies

eve: 31.28 MB (26.7%)
@typescript/typescript-linux-x64: 27.95 MB (23.9%)
@rolldown/binding-linux-x64-gnu: 19.10 MB (16.3%)
zod: 10.37 MB (8.9%)
ai: 7.56 MB (6.5%)

Installed footprint breakdown

Installed package size
🔴 eve                              [########################] 31.28 MB 26.7%
🔴 @typescript/typescript-linux-x64 [#####################...] 27.95 MB 23.9%
🔴 @rolldown/binding-linux-x64-gnu  [###############.........] 19.10 MB 16.3%
🔴 zod                              [########................] 10.37 MB 8.9%
🔴 ai                               [######..................] 7.56 MB 6.5%
🟠 undici                           [###.....................] 3.51 MB 3.0%
🔴 Other installed packages         [#############...........] 17.22 MB 14.7%

dependencies (4)

Package	Range	Installed size	Share
`@vercel/connect`	`2.2.0`	188.7 kB	0.2%
`ai`	`^7.0.105`	7.56 MB	6.5%
`eve`	`file:eve-0.59.0.tgz`	31.28 MB	26.7%
`zod`	`4.5.4`	10.37 MB	8.9%

devDependencies (2)

Package	Range	Installed size	Share
`@types/node`	`24.x`	2.54 MB	2.2%
`typescript`	`7.0.2`	2.50 MB	2.1%

Function Drill-Down

Payload Size Graph

Unique function payload size and share of total
🔴 functions/.well-known/workflow/v1/flow.func     [########################] 10.31 MB 50.0%
🔴 functions/__server.func                         [########################] 10.31 MB 50.0%

Top Function Payloads

🟠 functions/.well-known/workflow/v1/flow.func • 1 public route • 10.31 MB

Metric	Value
Public routes	`/.well-known/workflow/v1/flow`
Runtime	`nodejs24.x`
Handler	`index.mjs`
Payload	10.31 MB
Function files	10.31 MB across 110 files
Traced dependencies	0 B
Signal	🟠 Bundled file `index.mjs` is 2.26 MB (21.9%)

🟠 🔎 Dependency Analysis

📦 Bundled files:

Bundled file size
🟠 index.mjs                        [###########.............] 2.26 MB 21.9%
🟡 _libs/undici.mjs                 [#####...................] 980.8 kB 9.5%
🟡 _chunks/sandbox.mjs              [####....................] 804.5 kB 7.8%
🟡 _chunks/chatgpt-model.mjs        [###.....................] 699.0 kB 6.8%
🟡 _chunks/signal-exit-Dsy-TT0V.mjs [###.....................] 616.2 kB 6.0%
🔴 Other bundled files              [########################] 4.95 MB 48.0%

🧾 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 • 10.31 MB

Metric	Value
Public routes	`/` `/.well-known/workflow/v1/webhook/[token]` `/eve/v1/activity/[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/task-input/[token]`
Internal aliases	`/__server`
Runtime	`nodejs24.x`
Handler	`index.mjs`
Payload	10.31 MB
Function files	10.31 MB across 110 files
Traced dependencies	0 B
Signal	🟠 Bundled file `index.mjs` is 2.26 MB (21.9%)

🟠 🔎 Dependency Analysis

📦 Bundled files:

Bundled file size
🟠 index.mjs                        [###########.............] 2.26 MB 21.9%
🟡 _libs/undici.mjs                 [#####...................] 980.8 kB 9.5%
🟡 _chunks/sandbox.mjs              [####....................] 804.5 kB 7.8%
🟡 _chunks/chatgpt-model.mjs        [###.....................] 699.0 kB 6.8%
🟡 _chunks/signal-exit-Dsy-TT0V.mjs [###.....................] 616.2 kB 6.0%
🔴 Other bundled files              [########################] 4.95 MB 48.0%

🧾 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: 5.93 s -> 5.90 s (-23.3 ms) vs main (1e872e3).
Timing is informational: shared GitHub runners are too variable for a hard timing budget.

Detailed phase timings vs `main (1e872e3)`

Phase	Baseline	Current	Delta
`extension.check`	0.8 ms	0.8 ms	0.0 ms
`project.resolve`	0.4 ms	0.3 ms	-0.1 ms
`workspace.create`	0.6 ms	0.6 ms	0.0 ms
`host.prepare`	543.6 ms	510.0 ms	-33.6 ms
`vercel.service-prefix.resolve`	2.2 ms	2.1 ms	-0.1 ms
`nitro.create`	536.8 ms	562.0 ms	+25.2 ms
`sandbox.prewarm`	433.9 ms	397.7 ms	-36.2 ms
`nitro.cache.prepare`	0.3 ms	0.2 ms	-0.1 ms
`nitro.prepare`	0.8 ms	0.8 ms	0.0 ms
`nitro.public-assets`	0.8 ms	0.7 ms	-0.1 ms
`nitro.prerender`	0.5 ms	0.5 ms	0.0 ms
`nitro.bundle`	4.35 s	4.37 s	+21.4 ms
`nitro.cache.write`	0.4 ms	0.4 ms	0.0 ms
`vercel.workflow-function.materialize`	48.7 ms	49.3 ms	+0.6 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

AndrewBarba added 2 commits September 17, 2026 16:54

feat(eve): a2a - implement client and channel support

5c51bd3

Signed-off-by: Andrew Barba <barba@hey.com>

docs(eve): a2a - link protocol support issue

5e419a3

Signed-off-by: Andrew Barba <barba@hey.com>

AndrewBarba requested review from cmpadden, ctgowrie, ijjk and ruiconti as code owners September 17, 2026 20:56

vercel Bot deployed to Preview – eve-pkg September 17, 2026 20:56 View deployment

AndrewBarba requested review from OwenKephart, benpankow, chadhietala and prha as code owners September 17, 2026 20:56

vercel Bot deployed to Preview – eve-docs September 17, 2026 20:57 View deployment

AndrewBarba marked this pull request as draft September 17, 2026 21:15

Navigation Menu

feat(eve): a2a - implement client and channel support - #3487

feat(eve): a2a - implement client and channel support#3487
AndrewBarba wants to merge 2 commits into
mainfrom
barba/a2a-protocol

AndrewBarba commented Sep 17, 2026

Uh oh!

vercel Bot commented Sep 17, 2026 •

edited

Loading

Uh oh!

socket-security Bot commented Sep 17, 2026

Uh oh!

github-actions Bot commented Sep 17, 2026

Package Details

`eve init` install details

Payload Size Graph

Top Function Payloads

Uh oh!

This branch was successfully deployed

Reviewers

Assignees

Labels

Projects

Milestone

Development

Uh oh!

1 participant

Conversation

AndrewBarba commented Sep 17, 2026

Summary

Validation

Checklist

Uh oh!

vercel Bot commented Sep 17, 2026 • edited Loading Uh oh! There was an error while loading. Please reload this page.

Uh oh!

Uh oh!

socket-security Bot commented Sep 17, 2026

Uh oh!

github-actions Bot commented Sep 17, 2026

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

Delta vs main (1e872e3)

eve init install

Package Details

eve init install details

Payload Size Graph

Top Function Payloads

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

Uh oh!

This branch was successfully deployed

Reviewers

Assignees

Labels

Projects

Milestone

Development

Uh oh!

1 participant

vercel Bot commented Sep 17, 2026 •

edited

Loading

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

Delta vs `main (1e872e3)`

`eve init` install

`eve init` install details

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