Luca Forstner (lforst) · Aug 19, 2026 · Aug 19, 2026 · Aug 19, 2026 · Aug 20, 2026 · Aug 26, 2026
diff --git a/.agents/skills/instrumentation/SKILL.md b/.agents/skills/instrumentation/SKILL.md
@@ -52,7 +52,7 @@ Map the change before editing:
 - Pass `Error` objects directly as `span.log({ error })` values. The SDK serializes errors correctly, so do not add local helpers that manually turn errors into message/stack strings unless an external API requires a non-`Error` representation.
 - Log only the useful surface. Prefer narrow, stable payloads over dumping full request/response objects; exclude redundant or overly large data when possible.
 - Automatic capture of inline multimodal bytes as Braintrust attachments must be opt-in.
-  Guard attachment creation and binary observation with `BRAINTRUST_CAPTURE_ATTACHMENTS`, and enable them only when its value is `1` or `true`.
+  Guard attachment creation and binary observation with `BRAINTRUST_AUTO_CAPTURE_ATTACHMENTS`, and enable them only when its value is `1` or `true`.
   Audio/video recordings may contain personal data and are separately controlled with their own explicit flags (`BRAINTRUST_CAPTURE_USER_AUDIO_ATTACHMENTS`, `BRAINTRUST_CAPTURE_AGENT_AUDIO_ATTACHMENTS`): enabling the shared flag for other media never records audio/video without these being enabled.
   Preserve useful text, metadata, metrics, and remote references when attachment capture is disabled, and omit inline bytes from logged payloads.
 - Segmentable streaming media must use the shared `configureInstrumentation({ streamingAttachmentBufferBytes })` setting instead of provider-specific chunk-size or time-based controls.

diff --git a/.changeset/add-node-engine.md b/.changeset/add-node-engine.md
@@ -0,0 +1,5 @@
+---
+"braintrust": major
+---
+
+feat(v4)!: Add Node Engine to package json
diff --git a/.changeset/breezy-lines-draw.md b/.changeset/breezy-lines-draw.md
@@ -0,0 +1,10 @@
+---
+"@braintrust/browser": major
+"@braintrust/deepseek-harness": major
+"@braintrust/otel": major
+"@braintrust/templates-nunjucks-js": major
+"@braintrust/temporal": major
+"braintrust": major
+---
+
+build(sdk)!: Migrate to Vite+ and tree-shakeable ESM
diff --git a/.changeset/chilly-ends-appear.md b/.changeset/chilly-ends-appear.md
@@ -0,0 +1,5 @@
+---
+"braintrust": patch
+---
+
+fix(instrumentation): Initialize tracing automatically in bundles
diff --git a/.changeset/light-plants-return.md b/.changeset/light-plants-return.md
@@ -0,0 +1,6 @@
+---
+"@braintrust/deepseek-harness": major
+"braintrust": major
+---
+
+feat!: Add `BRAINTRUST_CAPTURE_ATTACHMENTS` env var option and `captureAttachments` logger option for all integrations
diff --git a/.changeset/reduce-api-to-a-minimum.md b/.changeset/reduce-api-to-a-minimum.md
@@ -0,0 +1,8 @@
+---
+"braintrust": major
+"@braintrust/otel": major
+"@braintrust/browser": patch
+"@braintrust/temporal": patch
+---
+
+ref!: Reduce API to a minimum that makes sense
diff --git a/.changeset/remove-ai-sdk-v3.md b/.changeset/remove-ai-sdk-v3.md
@@ -0,0 +1,5 @@
+---
+"braintrust": major
+---
+
+ref(ai-sdk)!: Remove AI SDK v3 support
diff --git a/.changeset/remove-eve-pre-034.md b/.changeset/remove-eve-pre-034.md
@@ -0,0 +1,5 @@
+---
+"braintrust": major
+---
+
+ref(eve)!: Bump minimum eve version to `0.34.0`
diff --git a/.changeset/remove-flue-pre-v1.md b/.changeset/remove-flue-pre-v1.md
@@ -0,0 +1,5 @@
+---
+"braintrust": major
+---
+
+ref(v4)!: Remove flue pre-v1 support
diff --git a/.changeset/remove-flush-async.md b/.changeset/remove-flush-async.md
@@ -0,0 +1,5 @@
+---
+"braintrust": major
+---
+
+ref!: Remove `flushAsync` option
diff --git a/.changeset/remove-js-braintrust-cli.md b/.changeset/remove-js-braintrust-cli.md
@@ -0,0 +1,5 @@
+---
+"braintrust": major
+---
+
+ref(v4)!: Remove JS Braintrust CLI
diff --git a/.changeset/remove-packaged-bt.md b/.changeset/remove-packaged-bt.md
@@ -0,0 +1,5 @@
+---
+"braintrust": major
+---
+
+ref!: Remove packaged `bt` binary from `braintrust` package
diff --git a/.changeset/remove-plugins-public-api.md b/.changeset/remove-plugins-public-api.md
@@ -0,0 +1,5 @@
+---
+"braintrust": major
+---
+
+ref!: Remove plugins as part of public API
diff --git a/.changeset/remove-zod-derived-types.md b/.changeset/remove-zod-derived-types.md
@@ -0,0 +1,5 @@
+---
+"braintrust": major
+---
+
+ref!: Remove Zod derived types from public SDK declarations
diff --git a/.changeset/shy-parents-return.md b/.changeset/shy-parents-return.md
@@ -0,0 +1,6 @@
+---
+"braintrust": major
+"@braintrust/deepseek-harness": major
+---
+
+refactor(sdk)!: Rename automatic attachment capture options
diff --git a/.changeset/simplify-eval-types.md b/.changeset/simplify-eval-types.md
@@ -0,0 +1,5 @@
+---
+"braintrust": major
+---
+
+ref!: Simplify Eval type definitions
diff --git a/.changeset/simplify-public-sdk-types.md b/.changeset/simplify-public-sdk-types.md
@@ -0,0 +1,5 @@
+---
+"braintrust": major
+---
+
+ref!: Don't make generated types part of public api
diff --git a/.github/dependabot.yml b/.github/dependabot.yml
@@ -37,12 +37,12 @@ updates:
           - "eslint"
           - "@typescript-eslint/*"
           - "prettier"
-          - "turbo"
           - "typescript"
-          - "tsup"
           - "tsx"
           - "vitest"
           - "vite"
+          - "vite-plus"
+          - "@voidzero-dev/*"
           - "vite-tsconfig-paths"
           - "rollup"
           - "webpack"

diff --git a/.github/scripts/npm-download-stats.ts b/.github/scripts/npm-download-stats.ts
@@ -212,7 +212,7 @@ async function main() {
     method: "POST",
     headers: {
       "Content-Type": "application/json",
-      "DD-API-KEY": ddApiKey,
+      "DD-API-KEY": ddApiKey!,
     },
     body: JSON.stringify(payload),
   });

diff --git a/.github/workflows/checks.yaml b/.github/workflows/checks.yaml
@@ -40,8 +40,8 @@ jobs:
         uses: pnpm/action-setup@ea17c68df8912ef543352723c149a84f56e3d413 # v6.1.0
       - name: Install dependencies
         run: pnpm install --frozen-lockfile
-      - name: Lint
-        run: pnpm run lint
+      - name: Static checks
+        run: pnpm run check
 
   check-typings:
     runs-on: ubuntu-latest
@@ -88,9 +88,7 @@ jobs:
       fail-fast: false
       matrix:
         os: [ubuntu-latest, windows-2025-vs2026]
-        node-version: [20, 22, 24, 26]
-    env:
-      ACTIONS_ALLOW_USE_UNSECURE_NODE_VERSION: ${{ matrix.node-version == 20 && 'true' || '' }}
+        node-version: [22.18.0, 24, 26]
     steps:
       - uses: actions/checkout@3d3c42e5aac5ba805825da76410c181273ba90b1 # v7.0.1
       - uses: actions/setup-node@48b55a011bda9f5d6aeb4c2d9c7362e8dae4041e # v6.4.0
@@ -226,9 +224,7 @@ jobs:
     strategy:
       fail-fast: false
       matrix:
-        node-version: [20]
-    env:
-      ACTIONS_ALLOW_USE_UNSECURE_NODE_VERSION: "true"
+        node-version: [22.18.0]
     steps:
       - uses: actions/checkout@3d3c42e5aac5ba805825da76410c181273ba90b1 # v7.0.1
         with:
@@ -267,11 +263,13 @@ jobs:
           pnpm install --frozen-lockfile || { echo "Baseline install failed"; git checkout "$CURRENT_REF"; exit 0; }
           pnpm run build || { echo "Baseline build failed"; git checkout "$CURRENT_REF"; exit 0; }
 
-          mkdir -p "$BASELINE_DIR/js/dev" "$BASELINE_DIR/js/util"
+          mkdir -p "$BASELINE_DIR/js/util"
           cp -R js/dist "$BASELINE_DIR/js/"
-          cp -R js/dev/dist "$BASELINE_DIR/js/dev/"
-          cp -R js/util/dist "$BASELINE_DIR/js/util/"
-          echo "Copied js/dist, js/dev/dist, and js/util/dist to baseline"
+          cp js/package.json "$BASELINE_DIR/js/"
+          if [ -d js/util/dist ]; then
+            cp -R js/util/dist "$BASELINE_DIR/js/util/"
+          fi
+          echo "Copied package metadata and build outputs to baseline"
 
           git checkout "$CURRENT_REF"
 
@@ -395,9 +393,7 @@ jobs:
     strategy:
       fail-fast: false
       matrix:
-        node-version: [20, 22, 24, 26]
-    env:
-      ACTIONS_ALLOW_USE_UNSECURE_NODE_VERSION: ${{ matrix.node-version == 20 && 'true' || '' }}
+        node-version: [22.18.0, 24, 26]
     steps:
       - uses: actions/checkout@3d3c42e5aac5ba805825da76410c181273ba90b1 # v7.0.1
       - uses: actions/setup-node@48b55a011bda9f5d6aeb4c2d9c7362e8dae4041e # v6.4.0
@@ -423,9 +419,7 @@ jobs:
     strategy:
       fail-fast: false
       matrix:
-        node-version: [20, 22, 24, 26]
-    env:
-      ACTIONS_ALLOW_USE_UNSECURE_NODE_VERSION: ${{ matrix.node-version == 20 && 'true' || '' }}
+        node-version: [22.18.0, 24, 26]
     steps:
       - uses: actions/checkout@3d3c42e5aac5ba805825da76410c181273ba90b1 # v7.0.1
       - uses: actions/setup-node@48b55a011bda9f5d6aeb4c2d9c7362e8dae4041e # v6.4.0
@@ -451,9 +445,7 @@ jobs:
     strategy:
       fail-fast: false
       matrix:
-        node-version: [20, 22, 24, 26]
-    env:
-      ACTIONS_ALLOW_USE_UNSECURE_NODE_VERSION: ${{ matrix.node-version == 20 && 'true' || '' }}
+        node-version: [22.18.0, 24, 26]
     steps:
       - uses: actions/checkout@3d3c42e5aac5ba805825da76410c181273ba90b1 # v7.0.1
       - uses: actions/setup-node@48b55a011bda9f5d6aeb4c2d9c7362e8dae4041e # v6.4.0
@@ -479,10 +471,8 @@ jobs:
     strategy:
       fail-fast: false
       matrix:
-        node-version: [20, 22, 24, 26]
+        node-version: [22.18.0, 24, 26]
         test-dir: [otel-v1, otel-v2]
-    env:
-      ACTIONS_ALLOW_USE_UNSECURE_NODE_VERSION: ${{ matrix.node-version == 20 && 'true' || '' }}
     steps:
       - uses: actions/checkout@3d3c42e5aac5ba805825da76410c181273ba90b1 # v7.0.1
       - name: Set up Docker Buildx
@@ -532,17 +522,6 @@ jobs:
       - name: Run hermetic tests
         working-directory: ./js
         run: pnpm run test:checks
-      - name: Run zod v3 tests
-        if: matrix.zod-version == '3.25.34'
-        working-directory: ./js
-        run: |
-          pnpm test:zod-v3
-      - name: Run zod v4 tests
-        if: matrix.zod-version == '4.2.1'
-        working-directory: ./js
-        run: |
-          pnpm test:zod-v4
-
   checks-passed:
     name: checks-passed
     needs:

diff --git a/.gitignore b/.gitignore
@@ -24,3 +24,7 @@ tsconfig.tsbuildinfo
 # Auto-generated by @sentry/dotagents — do not commit these files.
 agents.lock
 .agents/.gitignore
+
+# Local bundle reports and before/after build artifacts.
+.context/
+.vite/
diff --git a/.prettierignore b/.prettierignore
diff --git a/.prettierrc b/.prettierrc
diff --git a/AGENTS.md b/AGENTS.md
@@ -25,6 +25,21 @@ mise install        # Install toolchain and dependencies
 pnpm run build      # Build all workspace packages (from repo root)
 ```
 
+## Public TypeScript APIs
+
+Do not derive SDK-owned public TypeScript types from Zod schemas (for example,
+with `z.infer`, `z.input`, `z.output`, or equivalent schema-derived aliases).
+Define public API types explicitly with interfaces, type aliases, or generated
+plain types. Generic APIs may still infer types from caller-provided schemas.
+When exporting a runtime validator, give it a compact public type such as
+`z.ZodType<PublicType>` and test that the validator and public type stay in sync.
+
+Zod-derived public declarations can expand into large schema implementation
+graphs. Those declarations are expensive for downstream TypeScript consumers to
+parse, instantiate, and type-check, increasing compile time, declaration size,
+and memory usage. They also expose validation-library implementation details as
+part of the SDK's API surface.
+
 ## Public API
 
 Keep public exports minimal. Generally, export only the requested runtime APIs and do not export types unless explicitly requested.
@@ -55,6 +70,8 @@ Span names should generally remain stable across calls and versions. Do not incl
 
 Uses Vitest. Prefer running the **narrowest relevant test** rather than the full suite.
 
+Generally, do not add tests for build or linting code or their configuration. Validate tooling changes by running the relevant build or lint commands instead.
+
 **From `js/` directory:**
 
 ```bash

diff --git a/README.md b/README.md
@@ -34,27 +34,25 @@ Eval("Say Hi Bot", {
 });
 ```
 
-Run it:
+Install the `bt` CLI separately using the standalone installation instructions in the [CLI quickstart](https://www.braintrust.dev/docs/reference/cli/quickstart), then run it:
 
 ```bash
-BRAINTRUST_API_KEY=<YOUR_API_KEY> npx braintrust eval tutorial.eval.ts
+BRAINTRUST_API_KEY=<YOUR_API_KEY> bt eval tutorial.eval.ts
 ```
 
 ## Packages
 
-| Package                     | Purpose                                                                         | npm                                                                                                                                                          | Docs                                                                               |
-| --------------------------- | ------------------------------------------------------------------------------- | ------------------------------------------------------------------------------------------------------------------------------------------------------------ | ---------------------------------------------------------------------------------- |
-| `braintrust`                | Core JavaScript/TypeScript SDK for logging, tracing, evals, and CLI.            | [![npm: braintrust](https://img.shields.io/npm/v/braintrust.svg)](https://www.npmjs.com/package/braintrust)                                                  | [js/README.md](js/README.md)                                                       |
-| `@braintrust/browser`       | Browser-focused SDK integration with AsyncLocalStorage polyfill support.        | [![npm: @braintrust/browser](https://img.shields.io/npm/v/%40braintrust%2Fbrowser.svg)](https://www.npmjs.com/package/@braintrust/browser)                   | [integrations/browser-js/README.md](integrations/browser-js/README.md)             |
-| `@braintrust/langchain-js`  | Deprecated; use the LangChain integration in `braintrust` instead.              | [![npm: @braintrust/langchain-js](https://img.shields.io/npm/v/%40braintrust%2Flangchain-js.svg)](https://www.npmjs.com/package/@braintrust/langchain-js)    | [integrations/langchain-js/README.md](integrations/langchain-js/README.md)         |
-| `@braintrust/openai-agents` | Deprecated; use the OpenAI Agents integration in `braintrust` instead.          | [![npm: @braintrust/openai-agents](https://img.shields.io/npm/v/%40braintrust%2Fopenai-agents.svg)](https://www.npmjs.com/package/@braintrust/openai-agents) | [integrations/openai-agents-js/README.md](integrations/openai-agents-js/README.md) |
-| `@braintrust/otel`          | OpenTelemetry span processor and compatibility helpers for Braintrust tracing.  | [![npm: @braintrust/otel](https://img.shields.io/npm/v/%40braintrust%2Fotel.svg)](https://www.npmjs.com/package/@braintrust/otel)                            | [integrations/otel-js/README.md](integrations/otel-js/README.md)                   |
-| `@braintrust/temporal`      | Temporal client/worker plugin and workflow interceptors for Braintrust tracing. | [![npm: @braintrust/temporal](https://img.shields.io/npm/v/%40braintrust%2Ftemporal.svg)](https://www.npmjs.com/package/@braintrust/temporal)                | [integrations/temporal-js/README.md](integrations/temporal-js/README.md)           |
+| Package                | Purpose                                                                         | npm                                                                                                                                           | Docs                                                                     |
+| ---------------------- | ------------------------------------------------------------------------------- | --------------------------------------------------------------------------------------------------------------------------------------------- | ------------------------------------------------------------------------ |
+| `braintrust`           | Core JavaScript/TypeScript SDK for logging, tracing, and evals.                 | [![npm: braintrust](https://img.shields.io/npm/v/braintrust.svg)](https://www.npmjs.com/package/braintrust)                                   | [js/README.md](js/README.md)                                             |
+| `@braintrust/browser`  | Browser-focused SDK integration with AsyncLocalStorage polyfill support.        | [![npm: @braintrust/browser](https://img.shields.io/npm/v/%40braintrust%2Fbrowser.svg)](https://www.npmjs.com/package/@braintrust/browser)    | [integrations/browser-js/README.md](integrations/browser-js/README.md)   |
+| `@braintrust/otel`     | OpenTelemetry span processor and compatibility helpers for Braintrust tracing.  | [![npm: @braintrust/otel](https://img.shields.io/npm/v/%40braintrust%2Fotel.svg)](https://www.npmjs.com/package/@braintrust/otel)             | [integrations/otel-js/README.md](integrations/otel-js/README.md)         |
+| `@braintrust/temporal` | Temporal client/worker plugin and workflow interceptors for Braintrust tracing. | [![npm: @braintrust/temporal](https://img.shields.io/npm/v/%40braintrust%2Ftemporal.svg)](https://www.npmjs.com/package/@braintrust/temporal) | [integrations/temporal-js/README.md](integrations/temporal-js/README.md) |
 
 ## CLI `bt`
 
-The `bt` cli is installed alongside `braintrust`, use it with `npx bt` or `pnpm exec bt`.
-See the [documentation](https://www.braintrust.dev/docs/reference/cli/quickstart).
+The `bt` CLI is installed separately from `braintrust`.
+See the standalone installation instructions in the [CLI quickstart](https://www.braintrust.dev/docs/reference/cli/quickstart).
 
 ## Documentation
 

diff --git a/dev-packages/seinfeld/package.json b/dev-packages/seinfeld/package.json
@@ -5,33 +5,33 @@
   "type": "module",
   "license": "MIT",
   "engines": {
-    "node": ">=18"
+    "node": ">=22.18.0"
   },
-  "main": "./dist/index.cjs",
+  "main": "./dist/index.js",
   "module": "./dist/index.js",
   "types": "./dist/index.d.ts",
   "exports": {
     ".": {
       "types": "./dist/index.d.ts",
-      "import": "./dist/index.js",
-      "require": "./dist/index.cjs"
+      "default": "./dist/index.js"
     }
   },
   "files": [
     "dist"
   ],
   "scripts": {
-    "build": "tsup",
+    "build": "vp run compile",
     "check:typings": "tsc --noEmit",
-    "dev": "tsup --watch",
+    "dev": "vp pack --watch",
     "typecheck": "tsc --noEmit"
   },
   "dependencies": {
     "zod": "^3.23.8"
   },
   "devDependencies": {
     "@types/node": "^22.10.0",
-    "tsup": "^8.5.1",
-    "typescript": "^5.7.2"
-  }
+    "typescript": "^5.7.2",
+    "vite-plus": "catalog:"
+  },
+  "sideEffects": false
 }