feat(eve): add session snapshots

[timolins]

Description

Server-rendered apps need the existing events and the exact cursor to continue from. Eve already has the pieces for this, but every app currently has to collect a bounded stream and assemble that state itself.

This adds ClientSession.snapshot() as the simple path:

const session = client.session({ sessionId, streamIndex: 0 });
const snapshot = await session.snapshot();

The snapshot reads from the start of the session through the durable tail observed when the request opens, then returns:

• events, ready to use as the initial conversation
• session, positioned exactly after those events so streaming can continue without a gap

The original session handle stays unchanged, which makes snapshots safe to use for server rendering and other read-only consumers.

How did you test your changes?

Added coverage for waiting, active, completed, failed, empty, aborted, and preserved-completion sessions.

• pnpm --filter eve exec vitest run --config vitest.unit.config.ts src/client/session.test.ts
• pnpm typecheck
• pnpm docs:check
• pnpm guard:invariants
• pnpm lint
• oxfmt --check
• git diff --check

PR Checklist

• I linked an issue with prior discussion confirming this change is wanted
• 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)

[vercel]

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

Project	Deployment	Actions	Updated (UTC)
eve-docs	Ready	Preview	Jul 31, 2026 8:44am
eve-docs-4759	Ready	Preview, v0	Jul 31, 2026 8:44am

[github-actions]

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

Key takeaways

• Package delta: install footprint 85.76 MB -> 84.81 MB (-950.3 kB ✅).

Delta vs main (dbc8eae)

Area	Metric	Baseline	Current	Delta
Package	Packed tarball	7.62 MB	7.46 MB	-157.2 kB ✅
Package	Unpacked publish size	28.79 MB	27.84 MB	-950.3 kB ✅
Package	Installed footprint	85.76 MB	84.81 MB	-950.3 kB ✅
Package	Published files	2875	2893	+18
Package	Installed files	6668	6686	+18
Runtime	Unique function payloads	2	2	0
Runtime	Total function bytes	16.80 MB	16.90 MB	+97.5 kB ⚠️
Runtime	Public routes	11	11	0

Changed function payloads vs main (dbc8eae) (2)

Function	Status	Baseline	Current	Delta	Route changes
functions/__server.func	changed	8.40 MB	8.45 MB	+48.7 kB ⚠️	none
functions/.well-known/workflow/v1/flow.func	changed	8.40 MB	8.45 MB	+48.7 kB ⚠️	none

eve init install

Metric	Baseline	Current	Delta
Installed footprint	124.17 MB	123.23 MB	-942.9 kB ✅
Installed packages	130	128	-2
dependencies	4	4	0
devDependencies	2	2	0
Dependency package bytes	43.15 MB	42.21 MB	-941.7 kB ✅
devDependency package bytes	5.04 MB	5.04 MB	0 B ➖

eve init dependency changes vs main (dbc8eae)

dependencies

• Changed: @vercel/connect@0.4.2 -> @vercel/connect@0.4.3, eve@file:eve-0.27.13.tgz -> eve@file:eve-0.29.2.tgz

Build Metadata

• Preset: vercel
• Nitro: nitro@3.0.260610-beta
• Output directory: apps/fixtures/weather-agent/.vercel/output
• Build metadata timestamp: 2026-07-31T08:45:30.683Z
• 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: 7.46 MB (eve-0.29.2.tgz)
• Unpacked payload: 27.84 MB across 2893 published files
• Installed footprint: 84.81 MB across 6686 installed files
• Installed root package: 26.49 MB
• Installed dependencies: 58.33 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: 26.49 MB (31.2%)
• @rolldown/binding-linux-x64-gnu: 19.28 MB (22.7%)
• @rolldown/binding-wasm32-wasi: 10.66 MB (12.6%)
• ai: 6.56 MB (7.7%)
• zod: 5.07 MB (6.0%)

Publish payload breakdown

Published file size
🔴 dist/src/compiled/shadcn-registry/index.js       [##################......] 9.68 MB 34.8%
🟠 dist/src/compiled/@photon-ai/chat-adapter-ime... [####....................] 2.42 MB 8.7%
🟠 dist/src/compiled/experimental-ai-sdk-code-mo... [###.....................] 1.51 MB 5.4%
🟡 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                            [########################] 13.23 MB 47.5%

Installed footprint breakdown

Installed package size
🔴 eve                             [########################] 26.49 MB 31.2%
🔴 @rolldown/binding-linux-x64-gnu [#################.......] 19.28 MB 22.7%
🔴 @rolldown/binding-wasm32-wasi   [##########..............] 10.66 MB 12.6%
🔴 ai                              [######..................] 6.56 MB 7.7%
🔴 zod                             [#####...................] 5.07 MB 6.0%
🟠 undici                          [###.....................] 3.50 MB 4.1%
🔴 Other installed packages        [############............] 13.26 MB 15.6%

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: 123.23 MB across 8562 installed files
• Installed packages: 128 total (122 transitive-only)
• dependencies: 4 direct packages totaling 42.21 MB
• devDependencies: 2 direct packages totaling 5.04 MB
• Other transitive package files: 75.97 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 (22.7%)
• eve: 26.49 MB (21.5%)
• @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 22.7%
🔴 eve                              [#######################.] 26.49 MB 21.5%
🔴 @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                               [######..................] 6.56 MB 5.3%
🔴 Other installed packages         [####################....] 23.27 MB 18.9%

dependencies (4)

Package	Range	Installed size	Share
@vercel/connect	0.4.3	141.0 kB	0.1%
ai	^7.0.38	6.56 MB	5.3%
eve	file:eve-0.29.2.tgz	26.49 MB	21.5%
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     [########################] 8.45 MB 50.0%
🔴 functions/__server.func                         [########################] 8.45 MB 50.0%

Top Function Payloads

🟠 functions/.well-known/workflow/v1/flow.func • 1 public route • 8.45 MB

Metric	Value
Public routes	/.well-known/workflow/v1/flow
Runtime	nodejs24.x
Handler	index.mjs
Payload	8.45 MB
Function files	8.45 MB across 43 files
Traced dependencies	0 B
Signal	🟠 Bundled file index.mjs is 2.31 MB (27.3%)

🟠 🔎 Dependency Analysis

📦 Bundled files:

Bundled file size
🟠 index.mjs                       [#######################.] 2.31 MB 27.3%
🟠 _chunks/runtime-artifacts.mjs   [################........] 1.59 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 28.0%

🧾 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 • 10 public routes, 1 internal alias • 8.45 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	8.45 MB
Function files	8.45 MB across 43 files
Traced dependencies	0 B
Signal	🟠 Bundled file index.mjs is 2.31 MB (27.3%)

🟠 🔎 Dependency Analysis

📦 Bundled files:

Bundled file size
🟠 index.mjs                       [#######################.] 2.31 MB 27.3%
🟠 _chunks/runtime-artifacts.mjs   [################........] 1.59 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             [########################] 2.36 MB 28.0%

🧾 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: 1.93 s -> 1.91 s (-21.4 ms) vs main (dbc8eae).
• Timing is informational: shared GitHub runners are too variable for a hard timing budget.

Detailed phase timings vs `main (dbc8eae)`

Phase	Baseline	Current	Delta
extension.check	1.1 ms	12.4 ms	+11.3 ms
project.resolve	0.6 ms	6.4 ms	+5.8 ms
workspace.create	0.7 ms	5.5 ms	+4.8 ms
host.prepare	148.9 ms	182.7 ms	+33.8 ms
vercel.service-prefix.resolve	2.4 ms	2.1 ms	-0.3 ms
nitro.create	234.4 ms	204.6 ms	-29.8 ms
sandbox.prewarm	198.4 ms	171.1 ms	-27.3 ms
nitro.cache.prepare	0.3 ms	0.3 ms	0.0 ms
nitro.prepare	0.8 ms	0.9 ms	+0.1 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	1.32 s	1.30 s	-19.5 ms
nitro.cache.write	0.4 ms	0.4 ms	0.0 ms
vercel.workflow-function.materialize	23.1 ms	22.8 ms	-0.3 ms
agent-summary.emit	0.4 ms	0.5 ms	+0.1 ms
nitro.close	0.2 ms	0.1 ms	-0.1 ms
output.publish	3.3 ms	3.4 ms	+0.1 ms
workspace.remove	2.1 ms	2.0 ms	-0.1 ms