fix(eve): limit subagent fan-out per step

[allenzhou101]

Summary

Stacked on the subagent depth guardrail PR. Adds the width/fan-out limit separately from recursion depth.

• adds limits.subagents.maxCallsPerStep with a default of 4
• starts only the allowed subagent calls from a single model step
• returns EVE_SUBAGENT_STEP_LIMIT_EXCEEDED subagent results for overflow calls instead of dispatching them
• tracks accepted/requested calls across split runtime-action batches for the same model step
• extends the deterministic e2e fixture with a fan-out overflow eval

Testing

• pnpm --filter eve exec vitest run --config vitest.unit.config.ts src/harness/subagent-limits.test.ts src/harness/tool-loop.test.ts src/internal/authored-definition/core.test.ts src/compiler/manifest.test.ts src/execution/session.test.ts src/execution/workflow-steps.test.ts test/resolve-agent.test.ts test/runtime-agent-graph.test.ts
• pnpm --filter eve run typecheck
• pnpm --filter eve run build
• pnpm --filter agent-subagent-limits run typecheck
• pnpm --filter agent-subagent-limits run test:e2e

[vercel]

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Project	Deployment	Actions	Updated (UTC)
eve-docs	Ready	Preview, Comment, Open in v0	Jul 1, 2026 3:41pm

[github-actions]

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

Key takeaways

• No notable deltas vs main (7d1084d).

Delta vs main (7d1084d)

Area	Metric	Baseline	Current	Delta
Package	Packed tarball	3.49 MB	3.49 MB	+1.8 kB ⚠️
Package	Unpacked publish size	12.70 MB	12.70 MB	+7.0 kB ⚠️
Package	Installed footprint	51.68 MB	51.69 MB	+7.0 kB ⚠️
Package	Published files	2388	2390	+2
Package	Installed files	5601	5603	+2
Runtime	Unique function payloads	2	2	0
Runtime	Total function bytes	9.22 MB	9.24 MB	+17.2 kB ⚠️
Runtime	Public routes	9	9	0

Changed function payloads vs main (7d1084d) (2)

Function	Status	Baseline	Current	Delta	Route changes
functions/.well-known/workflow/v1/flow.func	changed	5.75 MB	5.76 MB	+16.9 kB ⚠️	none
functions/__server.func	changed	3.47 MB	3.47 MB	+237 B ⚠️	none

eve init install

Metric	Baseline	Current	Delta
Installed footprint	91.46 MB	91.47 MB	+7.0 kB ⚠️
Installed packages	120	120	0
dependencies	4	4	0
devDependencies	2	2	0
Dependency package bytes	26.81 MB	26.81 MB	+7.0 kB ⚠️
devDependency package bytes	4.81 MB	4.81 MB	0 B ➖

Build Metadata

• Preset: vercel
• Nitro: nitro@3.0.260610-beta
• Output directory: apps/fixtures/weather-agent/.vercel/output
• Build metadata timestamp: 2026-07-01T15:42:01.231Z
• 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@0.17.2
• Package directory: packages/eve
• Tarball: 3.49 MB (eve-0.17.2.tgz)
• Unpacked payload: 12.70 MB across 2390 published files
• Installed footprint: 51.69 MB across 5603 installed files
• Installed root package: 11.43 MB
• Installed dependencies: 40.25 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: 19.18 MB (37.1%)
• eve: 11.43 MB (22.1%)
• ai: 6.29 MB (12.2%)
• zod: 5.04 MB (9.7%)
• nitro: 2.41 MB (4.7%)

Publish payload breakdown

Published file size
🟠 dist/src/compiled/experimental-ai-sdk-code-mo... [####....................] 1.51 MB 11.9%
🟡 dist/src/compiled/@workflow/core/runtime.js      [##......................] 794.4 kB 6.3%
🟡 dist/src/compiled/@vercel/sandbox/index.js       [##......................] 632.0 kB 5.0%
🟡 dist/src/compiled/@chat-adapter/slack/index.js   [#.......................] 436.6 kB 3.4%
🟡 dist/src/compiled/_chunks/workflow/attribute-... [#.......................] 371.6 kB 2.9%
🔴 Other published files                            [########################] 8.96 MB 70.6%

Installed footprint breakdown

Installed package size
🔴 @rolldown/binding-linux-x64-gnu [########################] 19.18 MB 37.1%
🔴 eve                             [##############..........] 11.43 MB 22.1%
🔴 ai                              [########................] 6.29 MB 12.2%
🔴 zod                             [######..................] 5.04 MB 9.7%
🟠 nitro                           [###.....................] 2.41 MB 4.7%
🟡 rolldown                        [#.......................] 771.7 kB 1.5%
🔴 Other installed packages        [########................] 6.57 MB 12.7%

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

eve init install drill-down

eve init install details

• Command: eve init my-agent
• Package manager: npm
• Installed footprint: 91.47 MB across 7355 installed files
• Installed packages: 120 total (114 transitive-only)
• dependencies: 4 direct packages totaling 26.81 MB
• devDependencies: 2 direct packages totaling 4.81 MB
• Other transitive package files: 59.84 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: 29.69 MB (32.5%)
• @rolldown/binding-linux-x64-gnu: 19.18 MB (21.0%)
• eve: 11.43 MB (12.5%)
• zod: 9.00 MB (9.8%)
• ai: 6.29 MB (6.9%)

Installed footprint breakdown

Installed package size
🔴 @typescript/typescript-linux-x64 [########################] 29.69 MB 32.5%
🔴 @rolldown/binding-linux-x64-gnu  [###############.........] 19.18 MB 21.0%
🔴 eve                              [#########...............] 11.43 MB 12.5%
🔴 zod                              [#######.................] 9.00 MB 9.8%
🔴 ai                               [#####...................] 6.29 MB 6.9%
🟠 @types/node                      [##......................] 2.54 MB 2.8%
🔴 Other installed packages         [###########.............] 13.34 MB 14.6%

dependencies (4)

Package	Range	Installed size	Share
@vercel/connect	0.2.2	98.6 kB	0.1%
ai	^7.0.0	6.29 MB	6.9%
eve	file:eve-0.17.2.tgz	11.43 MB	12.5%
zod	4.4.3	9.00 MB	9.8%

devDependencies (2)

Package	Range	Installed size	Share
@types/node	24.x	2.54 MB	2.8%
typescript	7.0.1-rc	2.27 MB	2.5%

Function Drill-Down

Payload Size Graph

Unique function payload size and share of total
🔴 functions/.well-known/workflow/v1/flow.func     [########################] 5.76 MB 62.4%
🟠 functions/__server.func                         [##############..........] 3.47 MB 37.6%

Top Function Payloads

🟠 functions/.well-known/workflow/v1/flow.func • 1 public route • 5.76 MB

Metric	Value
Public routes	/.well-known/workflow/v1/flow
Runtime	nodejs24.x
Handler	index.mjs
Payload	5.76 MB
Function files	5.76 MB across 26 files
Traced dependencies	0 B
Signal	🟠 Bundled file __eve_nitro_handler__.mjs is 1.99 MB (34.5%)

🟠 🔎 Dependency Analysis

📦 Bundled files:

Bundled file size
🟠 __eve_nitro_handler__.mjs              [########################] 1.99 MB 34.5%
🟠 _chunks/runtime.mjs                    [############............] 983.9 kB 17.1%
🟡 _chunks/sandbox.mjs                    [#########...............] 766.0 kB 13.3%
🟡 _chunks/attribute-changes-zAifvEhb.mjs [######..................] 473.4 kB 8.2%
🟡 _libs/@ai-sdk/gateway+[...].mjs        [#####...................] 413.5 kB 7.2%
🟠 Other bundled files                    [##############..........] 1.14 MB 19.7%

🧾 Vercel Config

{
  "handler": "index.mjs",
  "launcherType": "Nodejs",
  "shouldAddHelpers": false,
  "supportsResponseStreaming": true,
  "runtime": "nodejs24.x",
  "environment": {
    "NODE_OPTIONS": "--experimental-require-module"
  },
  "maxDuration": "max",
  "experimentalTriggers": [
    {
      "type": "queue/v2beta",
      "topic": "__eve776561746865722d6167656e74_wkf_workflow_*",
      "consumer": "default",
      "retryAfterSeconds": 5,
      "initialDelaySeconds": 0
    }
  ]
}

---

🟠 functions/__server.func • 8 public routes, 1 internal alias • 3.47 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	3.47 MB
Function files	3.47 MB across 21 files
Traced dependencies	0 B
Signal	🟠 Bundled file _chunks/dev-runtime-artifacts.mjs is 908.5 kB (26.2%)

🟠 🔎 Dependency Analysis

📦 Bundled files:

Bundled file size
🟠 _chunks/dev-runtime-artifacts.mjs      [########################] 908.5 kB 26.2%
🟠 _chunks/runtime.mjs                    [########################] 891.6 kB 25.7%
🟠 _chunks/sandbox.mjs                    [####################....] 766.0 kB 22.1%
🟡 _chunks/attribute-changes-zAifvEhb.mjs [############............] 449.0 kB 12.9%
⚪ _libs/zod.mjs                          [###.....................] 114.2 kB 3.3%
🟡 Other bundled files                    [#########...............] 343.7 kB 9.9%

🧾 Vercel Config

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