feat(eve): run subagents as background tasks behind experimental.tasks by ruiconti · Pull Request #1521 · vercel/eve

ruiconti · 2026-08-01T20:30:46Z

Part 4/5 of the experimental.tasks stack, on top of #1519. The flag now means something: every subagent dispatch (fresh start, agentId continuation, local and remote) returns a task receipt and the parent turn keeps moving.

Data flows, before → after (flag on)

Flow	Before	After
Terminal child result	child resumes the parent turn inbox token; the turn blocks in `waitForRuntimeActionResults` until every batch result arrives	child's reply token is the task run's private hook; the originating call resolves immediately with `{ taskId, status: "working" }`
Child HITL / authorization	adapter forwards to the parent turn inbox	same payloads land on the task run → `input_required` snapshot (authorization blocks, `authorization.completed` unblocks)
Ready notification	n/a — parent was always waiting	task run resumes the parent session hook with a deliver payload; a parked parent starts a turn, an active turn sees it at the next boundary. Terminal and `input_required` are the only wake triggers
Agent handle	settled when the batch resolves with the child's outcome	receipt carries a `parked` outcome, so the unchanged resolve path parks the handle at receipt; the address stays for follow-ups

The child wire itself is untouched — local notification, HITL forwarding, and the remote callback route all deliver to whatever token they were given. Delegation is a token-routing change, not a payload change.

Ordering

The task run is created before the child dispatch side effect, so a fast child always finds a live command hook. The command token is derived deterministically from (taskId, parent continuation token): a durable replay re-derives it and the duplicate run loses the hook claim.

Tool execution

task_peek/task_cancel run inside the dispatch step. Cancel commits cancelled on the run first, then propagates a cooperative abort through the handle address — a late child result can't revive the task.
task_await starts a small aggregation run that polls the selected snapshot streams and posts one tool-result to the turn's existing inbox wait. No new wait arm: the strict inbox filter only guards subagent-result kinds, so the result passes as-is. The run exits when the waiting turn's inbox is gone.
Parent finalization cancels live tasks before terminating children.

Scope

Flag off: dispatch behavior, wire shapes, and events unchanged — the agent-messaging scenario suite passes unmodified.
The flag implies conversation-mode children, so tasks and subagentPersistentSessions never produce a third mode.
Deferred: child usage accounting for delegated tasks (usageDelta reaches the task run but isn't folded into parent totals), progress/task_message.
subagent-start.ts is code motion out of the dispatch step (file-length cap).

Part of #1084.

vercel · 2026-08-01T20:30:53Z

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Project	Deployment	Actions	Updated (UTC)
eve-docs	Ready	Preview	Aug 1, 2026 10:15pm
eve-docs-4759	Ready	Preview, v0	Aug 1, 2026 10:15pm

github-actions · 2026-08-01T20:34:19Z

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

Key takeaways

No notable deltas vs tasks/03-tools (0906202).

Delta vs `tasks/03-tools (0906202)`

Area	Metric	Baseline	Current	Delta
Package	Packed tarball	7.61 MB	7.62 MB	+8.5 kB ⚠️
Package	Unpacked publish size	28.52 MB	28.54 MB	+26.3 kB ⚠️
Package	Installed footprint	85.51 MB	85.53 MB	+26.3 kB ⚠️
Package	Published files	2990	3002	+12
Package	Installed files	6785	6797	+12
Runtime	Unique function payloads	2	2	0
Runtime	Total function bytes	16.90 MB	16.96 MB	+66.0 kB ⚠️
Runtime	Public routes	11	11	0

Changed function payloads vs tasks/03-tools (0906202) (2)

Function	Status	Baseline	Current	Delta	Route changes
`functions/__server.func`	changed	8.45 MB	8.48 MB	+33.0 kB ⚠️	none
`functions/.well-known/workflow/v1/flow.func`	changed	8.45 MB	8.48 MB	+33.0 kB ⚠️	none

`eve init` install

Metric	Baseline	Current	Delta
Installed footprint	123.92 MB	123.94 MB	+26.3 kB ⚠️
Installed packages	128	128	0
dependencies	4	4	0
devDependencies	2	2	0
Dependency package bytes	42.90 MB	42.93 MB	+26.3 kB ⚠️
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: 2026-08-01T22:15:58.244Z
Route aliases: 11 public, 1 internal (12 total aliases)
Vercel routes in config: 14
Severity legend: 🔴 dominant/large, 🟠 notable, 🟡 watch, ⚪ small

Package Drill-Down

Package Details

Package: eve@0.29.4
Package directory: packages/eve
Tarball: 7.62 MB (eve-0.29.4.tgz)
Unpacked payload: 28.54 MB across 3002 published files
Installed footprint: 85.53 MB across 6797 installed files
Installed root package: 27.19 MB
Installed dependencies: 58.34 MB
Runtime dependencies: 2
Peer dependencies: 5 (4 optional)

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

Heavy installed dependencies

eve: 27.19 MB (31.8%)
@rolldown/binding-linux-x64-gnu: 19.28 MB (22.5%)
@rolldown/binding-wasm32-wasi: 10.66 MB (12.5%)
ai: 6.57 MB (7.7%)
zod: 5.07 MB (5.9%)

Publish payload breakdown

Published file size
🔴 dist/src/compiled/shadcn-registry/index.js       [#################.......] 9.68 MB 33.9%
🟠 dist/src/compiled/@photon-ai/chat-adapter-ime... [####....................] 2.42 MB 8.5%
🟠 dist/src/compiled/experimental-ai-sdk-code-mo... [###.....................] 1.51 MB 5.3%
🟡 dist/src/compiled/_chunks/node/undici-DWL_MYm... [#.......................] 502.4 kB 1.8%
🟡 dist/src/compiled/_chunks/workflow/undici-DWL... [#.......................] 502.4 kB 1.8%
🔴 Other published files                            [########################] 13.93 MB 48.8%

Installed footprint breakdown

Installed package size
🔴 eve                             [########################] 27.19 MB 31.8%
🔴 @rolldown/binding-linux-x64-gnu [#################.......] 19.28 MB 22.5%
🔴 @rolldown/binding-wasm32-wasi   [#########...............] 10.66 MB 12.5%
🔴 ai                              [######..................] 6.57 MB 7.7%
🔴 zod                             [####....................] 5.07 MB 5.9%
🟠 undici                          [###.....................] 3.50 MB 4.1%
🔴 Other installed packages        [############............] 13.26 MB 15.5%

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`	`^3.0.0`	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: 123.94 MB across 8673 installed files
Installed packages: 128 total (122 transitive-only)
dependencies: 4 direct packages totaling 42.93 MB
devDependencies: 2 direct packages totaling 5.04 MB
Other transitive package files: 75.98 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 (22.5%)
eve: 27.19 MB (21.9%)
@rolldown/binding-linux-x64-gnu: 19.28 MB (15.6%)
@rolldown/binding-wasm32-wasi: 10.66 MB (8.6%)
zod: 9.02 MB (7.3%)

Installed footprint breakdown

Installed package size
🔴 @typescript/typescript-linux-x64 [########################] 27.95 MB 22.5%
🔴 eve                              [#######################.] 27.19 MB 21.9%
🔴 @rolldown/binding-linux-x64-gnu  [#################.......] 19.28 MB 15.6%
🔴 @rolldown/binding-wasm32-wasi    [#########...............] 10.66 MB 8.6%
🔴 zod                              [########................] 9.02 MB 7.3%
🔴 ai                               [######..................] 6.57 MB 5.3%
🔴 Other installed packages         [####################....] 23.27 MB 18.8%

dependencies (4)

Package	Range	Installed size	Share
`@vercel/connect`	`0.4.3`	141.0 kB	0.1%
`ai`	`^7.0.38`	6.57 MB	5.3%
`eve`	`file:eve-0.29.4.tgz`	27.19 MB	21.9%
`zod`	`4.4.3`	9.02 MB	7.3%

devDependencies (2)

Package	Range	Installed size	Share
`@types/node`	`24.x`	2.54 MB	2.1%
`typescript`	`7.0.2`	2.50 MB	2.0%

Function Drill-Down

Payload Size Graph

Unique function payload size and share of total
🔴 functions/.well-known/workflow/v1/flow.func     [########################] 8.48 MB 50.0%
🔴 functions/__server.func                         [########################] 8.48 MB 50.0%

Top Function Payloads

🟠 functions/.well-known/workflow/v1/flow.func • 1 public route • 8.48 MB

Metric	Value
Public routes	`/.well-known/workflow/v1/flow`
Runtime	`nodejs24.x`
Handler	`index.mjs`
Payload	8.48 MB
Function files	8.48 MB across 44 files
Traced dependencies	0 B
Signal	🟠 Bundled file `index.mjs` is 2.33 MB (27.4%)

🟠 🔎 Dependency Analysis

📦 Bundled files:

Bundled file size
🟠 index.mjs                       [########################] 2.33 MB 27.4%
🟠 _chunks/runtime-artifacts.mjs   [################........] 1.61 MB 18.9%
🟡 _libs/undici.mjs                [##########..............] 980.5 kB 11.6%
🟡 _chunks/sandbox.mjs             [########................] 769.0 kB 9.1%
🟡 _libs/@ai-sdk/gateway+[...].mjs [####....................] 432.8 kB 5.1%
🟠 Other bundled files             [########################] 2.37 MB 27.9%

🧾 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 • 10 public routes, 1 internal alias • 8.48 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]/cancel` `/eve/v1/session/[sessionId]/stream` `/eve/v1/session/reset`
Internal aliases	`/__server`
Runtime	`nodejs24.x`
Handler	`index.mjs`
Payload	8.48 MB
Function files	8.48 MB across 44 files
Traced dependencies	0 B
Signal	🟠 Bundled file `index.mjs` is 2.33 MB (27.4%)

🟠 🔎 Dependency Analysis

📦 Bundled files:

Bundled file size
🟠 index.mjs                       [########################] 2.33 MB 27.4%
🟠 _chunks/runtime-artifacts.mjs   [################........] 1.61 MB 18.9%
🟡 _libs/undici.mjs                [##########..............] 980.5 kB 11.6%
🟡 _chunks/sandbox.mjs             [########................] 769.0 kB 9.1%
🟡 _libs/@ai-sdk/gateway+[...].mjs [####....................] 432.8 kB 5.1%
🟠 Other bundled files             [########################] 2.37 MB 27.9%

🧾 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: 2.03 s -> 1.94 s (-85.8 ms) vs tasks/03-tools (0906202).
Timing is informational: shared GitHub runners are too variable for a hard timing budget.

Detailed phase timings vs `tasks/03-tools (0906202)`

Phase	Baseline	Current	Delta
`extension.check`	6.5 ms	6.0 ms	-0.5 ms
`project.resolve`	6.5 ms	10.8 ms	+4.3 ms
`workspace.create`	1.4 ms	1.4 ms	0.0 ms
`host.prepare`	292.0 ms	149.2 ms	-142.8 ms
`vercel.service-prefix.resolve`	2.5 ms	2.4 ms	-0.1 ms
`nitro.create`	203.3 ms	217.2 ms	+13.9 ms
`sandbox.prewarm`	188.4 ms	180.3 ms	-8.1 ms
`nitro.cache.prepare`	0.3 ms	0.3 ms	0.0 ms
`nitro.prepare`	1.0 ms	0.9 ms	-0.1 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`	1.29 s	1.34 s	+47.8 ms
`nitro.cache.write`	0.4 ms	0.4 ms	0.0 ms
`vercel.workflow-function.materialize`	23.5 ms	24.0 ms	+0.5 ms
`agent-summary.emit`	0.4 ms	0.5 ms	+0.1 ms
`nitro.close`	0.1 ms	0.1 ms	0.0 ms
`output.publish`	3.6 ms	3.6 ms	0.0 ms
`workspace.remove`	2.8 ms	2.3 ms	-0.5 ms

vercel · 2026-08-01T20:36:37Z

+  for (
+    let attempt = 0;
+    attempt < CANCEL_COMMIT_POLL_ATTEMPTS &&
+    !(view !== undefined && isReadyTaskStatus(view.status));


cancelOneTask's commit-poll loop stops on isReadyTaskStatus, which is true for input_required, so cancelling a HITL-blocked task exits before the cancelled state commits — skipping child-turn abort propagation and returning a stale view.

With the flag on, every subagent dispatch (fresh start, agentId continuation, local and remote) becomes delegated execution: - the durable task run is created before the child dispatch side effect, so a fast child always finds a live command hook; a replay re-derives the same deterministic command token and the duplicate run loses the hook claim; - the child's reply address is the task run's private hook instead of the parent turn's inbox, so the existing local notification, HITL forwarding, and remote callback wires deliver to the task unchanged; - the originating call resolves immediately with a task receipt whose parked outcome settles the agent handle through the existing resolve path, keeping history provider-valid with exactly one result; - a dispatch that never acknowledges a child fails its task out of band and returns the failure directly, so the model never sees a task id for work that never started. The task run translates the child wire into lifecycle commands (settled turn outcomes to complete/fail/cancel, HITL batches to input_required, authorization events to blocked/unblocked) and wakes the parent through the ordinary session delivery path when a task becomes ready — a parked parent starts a turn, an active turn observes the notification at its next safe boundary. task_peek and task_cancel execute inside the dispatch step, which owns the session task index and world access; task_cancel commits cancelled before propagating a cooperative abort through the handle address. task_await rides the turn's existing inbox wait: a small aggregation run polls the selected snapshot streams and posts the one tool-result the pending key expects, exiting quietly when the waiting turn is gone. Parent finalization cancels live tasks before terminating children. The flag also implies conversation-mode children so experimental.tasks and experimental.subagentPersistentSessions never produce a third mode. Child usage accounting for delegated tasks is deferred; the subagent-start machinery moved to its own module to keep the dispatch step within the file-length cap. Without the flag, dispatch behavior, wire shapes, and events are unchanged (agent-messaging scenario suite passes unmodified). Signed-off-by: Rui Conti <ruiconti@gmail.com>

This was referenced Aug 1, 2026

feat(eve): add task_send for blocked and finished background tasks #1522

Open

feat(eve): add the experimental.tasks flag, plumbing only #1517

Open

vercel Bot deployed to Preview – eve-docs August 1, 2026 20:32 View deployment

vercel Bot reviewed Aug 1, 2026

View reviewed changes

ruiconti force-pushed the tasks/04-delegated branch from a61c317 to c020182 Compare August 1, 2026 22:13

ruiconti force-pushed the tasks/03-tools branch from d4f3d16 to 0906202 Compare August 1, 2026 22:13

vercel Bot deployed to Preview – eve-docs-4759 August 1, 2026 22:14 View deployment

vercel Bot deployed to Preview – eve-docs August 1, 2026 22:15 View deployment

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feat(eve): run subagents as background tasks behind experimental.tasks - #1521

feat(eve): run subagents as background tasks behind experimental.tasks#1521
ruiconti wants to merge 1 commit into
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ruiconti commented Aug 1, 2026

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Package Details

`eve init` install details

Payload Size Graph

Top Function Payloads

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ruiconti commented Aug 1, 2026

Data flows, before → after (flag on)

Ordering

Tool execution

Scope

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

Delta vs tasks/03-tools (0906202)

eve init install

Package Details

eve init install details

Payload Size Graph

Top Function Payloads

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

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

Delta vs `tasks/03-tools (0906202)`

`eve init` install

`eve init` install details

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

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