feat(eve): capture model and tool content on local trace spans by chadhietala · Pull Request #1443 · vercel/eve

chadhietala · 2026-07-31T03:11:23Z

Stacked on #1442 — base is trace-wrap-perf, review that first.

Local trace spans were structural only: names, timings, ids, usage. Any spool consumer — eve traces today, the /traces viewer up-stack — could show that a model call happened but not what was asked or answered. This layer puts the content on the spans.

What changed

With content capture on (the default), operation spans gain payload attributes:

span	attributes
model (`ai.*.doStream`)	`ai.prompt.system`, `ai.prompt.messages`, `ai.response.text`, `ai.response.reasoning`, `ai.response.tool_calls`, `ai.response.finish_reason`
tool (`ai.toolCall`)	`gen_ai.tool.call.arguments`, `gen_ai.tool.call.result`

EVE_TRACES_CONTENT=off disables capture entirely (documented in the instrumentation guide's env table). Structural spans (agent.turn, agent.step, agent.action) stay structural — content lives only on the operation spans.

Every attribute is capped at 32 KiB so one giant payload cannot bloat a spool segment past the reader's per-file limit. Messages are the interesting case: they must stay parseable through truncation, so oldest messages drop first behind an eve.truncated omission marker, and when even a single message exceeds the cap it is truncated at the text level rather than the JSON level. Provider transport noise (providerOptions, providerMetadata — signature blobs et al.) is stripped from messages, but deliberately not from tool data, where those keys may be legitimate domain fields the user authored or the tool returned.

Verification

Provider unit tests cover the capture shape, the strip rules, truncation keeping valid JSON with recent messages retained, and that capture-off leaves spans clean (17 tests at this layer). Sweep green; the full suite ran at the stack top.

Model spans record the system prompt, prompt messages, and the response (text, reasoning, tool calls, finish reason); tool spans record call arguments and results. Everything is capped at 32 KB — messages truncate oldest-first behind an omission marker so the attribute stays valid JSON — and provider transport metadata is stripped from messages. EVE_TRACES_CONTENT=off disables capture entirely. Signed-off-by: Chad Hietala <chadhietala@gmail.com>

vercel · 2026-07-31T03:11:30Z

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Project	Deployment	Actions	Updated (UTC)
eve-docs	Ready	Preview	Jul 31, 2026 3:12am
eve-docs-4759	Ready	Preview, v0	Jul 31, 2026 3:12am

github-actions · 2026-07-31T03:16:18Z

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

Key takeaways

No notable deltas vs trace-wrap-perf (e9fdb69).

Delta vs `trace-wrap-perf (e9fdb69)`

Area	Metric	Baseline	Current	Delta
Package	Packed tarball	7.63 MB	7.63 MB	+1.6 kB ⚠️
Package	Unpacked publish size	28.80 MB	28.81 MB	+6.1 kB ⚠️
Package	Installed footprint	91.31 MB	91.32 MB	+6.1 kB ⚠️
Package	Published files	2872	2874	+2
Package	Installed files	6665	6667	+2
Runtime	Unique function payloads	2	2	0
Runtime	Total function bytes	16.82 MB	16.82 MB	-40 B ✅
Runtime	Public routes	11	11	0

Changed function payloads vs trace-wrap-perf (e9fdb69) (2)

Function	Status	Baseline	Current	Delta	Route changes
`functions/__server.func`	changed	8.41 MB	8.41 MB	-20 B ✅	none
`functions/.well-known/workflow/v1/flow.func`	changed	8.41 MB	8.41 MB	-20 B ✅	none

`eve init` install

Metric	Baseline	Current	Delta
Installed footprint	129.71 MB	129.72 MB	+6.1 kB ⚠️
Installed packages	128	128	0
dependencies	4	4	0
devDependencies	2	2	0
Dependency package bytes	43.17 MB	43.17 MB	+6.1 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: 2026-07-31T03:15:29.503Z
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@0.29.2
Package directory: packages/eve
Tarball: 7.63 MB (eve-0.29.2.tgz)
Unpacked payload: 28.81 MB across 2874 published files
Installed footprint: 91.32 MB across 6667 installed files
Installed root package: 27.45 MB
Installed dependencies: 63.86 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: 27.45 MB (30.1%)
@rolldown/binding-linux-x64-gnu: 19.28 MB (21.1%)
@rolldown/binding-wasm32-wasi: 10.66 MB (11.7%)
@napi-rs/wasm-runtime: 6.56 MB (7.2%)
ai: 6.56 MB (7.2%)

Publish payload breakdown

Published file size
🔴 dist/src/compiled/shadcn-registry/index.js       [########################] 13.15 MB 45.7%
🟠 dist/src/compiled/experimental-ai-sdk-code-mo... [###.....................] 1.51 MB 5.2%
🟡 dist/src/compiled/@vercel/sandbox/index.js       [#.......................] 632.5 kB 2.2%
🟡 dist/src/compiled/_chunks/workflow/undici-DWL... [#.......................] 502.4 kB 1.7%
🟡 dist/src/compiled/@chat-adapter/slack/index.js   [#.......................] 440.5 kB 1.5%
🔴 Other published files                            [#######################.] 12.57 MB 43.6%

Installed footprint breakdown

Installed package size
🔴 eve                             [########################] 27.45 MB 30.1%
🔴 @rolldown/binding-linux-x64-gnu [#################.......] 19.28 MB 21.1%
🔴 @rolldown/binding-wasm32-wasi   [#########...............] 10.66 MB 11.7%
🔴 @napi-rs/wasm-runtime           [######..................] 6.56 MB 7.2%
🔴 ai                              [######..................] 6.56 MB 7.2%
🔴 zod                             [####....................] 5.07 MB 5.5%
🔴 Other installed packages        [##############..........] 15.73 MB 17.2%

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: 129.72 MB across 8535 installed files
Installed packages: 128 total (122 transitive-only)
dependencies: 4 direct packages totaling 43.17 MB
devDependencies: 2 direct packages totaling 5.04 MB
Other transitive package files: 81.50 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 (21.5%)
eve: 27.45 MB (21.2%)
@rolldown/binding-linux-x64-gnu: 19.28 MB (14.9%)
@rolldown/binding-wasm32-wasi: 10.66 MB (8.2%)
zod: 9.02 MB (7.0%)

Installed footprint breakdown

Installed package size
🔴 @typescript/typescript-linux-x64 [########################] 27.95 MB 21.5%
🔴 eve                              [########################] 27.45 MB 21.2%
🔴 @rolldown/binding-linux-x64-gnu  [#################.......] 19.28 MB 14.9%
🔴 @rolldown/binding-wasm32-wasi    [#########...............] 10.66 MB 8.2%
🔴 zod                              [########................] 9.02 MB 7.0%
🔴 @napi-rs/wasm-runtime            [######..................] 6.56 MB 5.1%
🔴 ai                               [######..................] 6.56 MB 5.1%
🔴 Other installed packages         [###################.....] 22.23 MB 17.1%

dependencies (4)

Package	Range	Installed size	Share
`@vercel/connect`	`0.4.2`	135.8 kB	0.1%
`ai`	`^7.0.38`	6.56 MB	5.1%
`eve`	`file:eve-0.29.2.tgz`	27.45 MB	21.2%
`zod`	`4.4.3`	9.02 MB	7.0%

devDependencies (2)

Package	Range	Installed size	Share
`@types/node`	`24.x`	2.54 MB	2.0%
`typescript`	`7.0.2`	2.50 MB	1.9%

Function Drill-Down

Payload Size Graph

Unique function payload size and share of total
🔴 functions/.well-known/workflow/v1/flow.func     [########################] 8.41 MB 50.0%
🔴 functions/__server.func                         [########################] 8.41 MB 50.0%

Top Function Payloads

🟠 functions/.well-known/workflow/v1/flow.func • 1 public route • 8.41 MB

Metric	Value
Public routes	`/.well-known/workflow/v1/flow`
Runtime	`nodejs24.x`
Handler	`index.mjs`
Payload	8.41 MB
Function files	8.41 MB across 43 files
Traced dependencies	0 B
Signal	🟠 Bundled file `index.mjs` is 2.31 MB (27.5%)

🟠 🔎 Dependency Analysis

📦 Bundled files:

Bundled file size
🟠 index.mjs                       [########################] 2.31 MB 27.5%
🟠 _chunks/runtime-artifacts.mjs   [################........] 1.59 MB 18.9%
🟡 _libs/undici.mjs                [##########..............] 980.5 kB 11.7%
🟡 _chunks/sandbox.mjs             [########................] 768.8 kB 9.1%
🟡 _libs/@ai-sdk/gateway+[...].mjs [####....................] 432.8 kB 5.1%
🟠 Other bundled files             [########################] 2.32 MB 27.6%

🧾 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 • 8.41 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	8.41 MB
Function files	8.41 MB across 43 files
Traced dependencies	0 B
Signal	🟠 Bundled file `index.mjs` is 2.31 MB (27.5%)

🟠 🔎 Dependency Analysis

📦 Bundled files:

Bundled file size
🟠 index.mjs                       [########################] 2.31 MB 27.5%
🟠 _chunks/runtime-artifacts.mjs   [################........] 1.59 MB 18.9%
🟡 _libs/undici.mjs                [##########..............] 980.5 kB 11.7%
🟡 _chunks/sandbox.mjs             [########................] 768.8 kB 9.1%
🟡 _libs/@ai-sdk/gateway+[...].mjs [####....................] 432.8 kB 5.1%
🟠 Other bundled files             [########################] 2.32 MB 27.6%

🧾 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: 2.05 s -> 2.00 s (-50.4 ms) vs trace-wrap-perf (e9fdb69).
Timing is informational: shared GitHub runners are too variable for a hard timing budget.

Detailed phase timings vs `trace-wrap-perf (e9fdb69)`

Phase	Baseline	Current	Delta
`extension.check`	8.9 ms	1.3 ms	-7.6 ms
`project.resolve`	3.3 ms	0.5 ms	-2.8 ms
`workspace.create`	1.2 ms	0.6 ms	-0.6 ms
`host.prepare`	225.1 ms	205.6 ms	-19.5 ms
`vercel.service-prefix.resolve`	1.7 ms	1.9 ms	+0.2 ms
`nitro.create`	191.4 ms	199.2 ms	+7.8 ms
`sandbox.prewarm`	290.9 ms	288.8 ms	-2.1 ms
`nitro.cache.prepare`	0.2 ms	0.3 ms	+0.1 ms
`nitro.prepare`	0.9 ms	0.9 ms	0.0 ms
`nitro.public-assets`	0.7 ms	0.7 ms	0.0 ms
`nitro.prerender`	0.4 ms	0.4 ms	0.0 ms
`nitro.bundle`	1.26 s	1.25 s	-11.4 ms
`nitro.cache.write`	0.4 ms	0.4 ms	0.0 ms
`vercel.workflow-function.materialize`	58.3 ms	44.1 ms	-14.2 ms
`agent-summary.emit`	0.5 ms	0.5 ms	0.0 ms
`nitro.close`	0.1 ms	0.1 ms	0.0 ms
`output.publish`	3.1 ms	2.9 ms	-0.2 ms
`workspace.remove`	1.8 ms	1.6 ms	-0.2 ms

chadhietala mentioned this pull request Jul 31, 2026

feat(eve): add the /traces conversation viewer to the dev TUI #1403

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vercel Bot deployed to Preview – eve-docs-4759 July 31, 2026 03:12 View deployment

vercel Bot deployed to Preview – eve-docs July 31, 2026 03:12 View deployment

chadhietala mentioned this pull request Jul 31, 2026

refactor(eve): extract the local trace reader into a shared harness module #1444

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chadhietala changed the title ~~Capture model and tool content on local trace spans~~ feat(eve): capture model and tool content on local trace spans Jul 31, 2026

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feat(eve): capture model and tool content on local trace spans - #1443

feat(eve): capture model and tool content on local trace spans#1443
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Bundle + Package Summary: apps/fixtures/weather-agent

Delta vs trace-wrap-perf (e9fdb69)

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 `trace-wrap-perf (e9fdb69)`

`eve init` install

`eve init` install details

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