diff --git a/.github/workflows/js.yaml b/.github/workflows/js.yaml
index ba40b3cad..81aa19881 100644
--- a/.github/workflows/js.yaml
+++ b/.github/workflows/js.yaml
@@ -57,6 +57,14 @@ jobs:
           PACKED_TARBALL=$(npm pack --pack-destination artifacts)
           echo "packed_tarball=$PACKED_TARBALL" >> "$GITHUB_OUTPUT"
 
+      - name: Pack @braintrust/browser
+        id: prepare_browser_artifact
+        working-directory: integrations/browser-js
+        shell: bash
+        run: |
+          PACKED_BROWSER_TARBALL=$(npm pack --pack-destination ../../js/artifacts)
+          echo "packed_browser_tarball=$PACKED_BROWSER_TARBALL" >> "$GITHUB_OUTPUT"
+
       - name: Build and pack @braintrust/otel
         id: prepare_otel_artifact
         shell: bash
@@ -89,11 +97,22 @@ jobs:
           PACKED_OTEL_TARBALL=$(npm pack --pack-destination ../../js/artifacts)
           echo "packed_otel_tarball=$PACKED_OTEL_TARBALL" >> "$GITHUB_OUTPUT"
 
+      - name: Build and pack @braintrust/templates-nunjucks
+        id: prepare_templates_nunjucks_artifact
+        shell: bash
+        run: |
+          cd integrations/templates-nunjucks
+          pnpm run build
+          PACKED_NUNJUCKS_TARBALL=$(npm pack --pack-destination ../../js/artifacts)
+          echo "packed_nunjucks_tarball=$PACKED_NUNJUCKS_TARBALL" >> "$GITHUB_OUTPUT"
+
       - name: List artifacts before upload
         shell: bash
         run: |
           echo "Braintrust tarball: ${{ steps.prepare_artifact.outputs.packed_tarball }}"
+          echo "Browser tarball: ${{ steps.prepare_browser_artifact.outputs.packed_browser_tarball }}"
           echo "Otel tarball: ${{ steps.prepare_otel_artifact.outputs.packed_otel_tarball }}"
+          echo "Templates-nunjucks tarball: ${{ steps.prepare_templates_nunjucks_artifact.outputs.packed_nunjucks_tarball }}"
           ls -la js/artifacts/
 
       - name: Upload build artifacts
@@ -102,7 +121,9 @@ jobs:
           name: ${{ steps.artifact.outputs.name }}-${{ matrix.node-version }}-dist
           path: |
             js/artifacts/${{ steps.prepare_artifact.outputs.packed_tarball }}
+            js/artifacts/${{ steps.prepare_browser_artifact.outputs.packed_browser_tarball }}
             js/artifacts/${{ steps.prepare_otel_artifact.outputs.packed_otel_tarball }}
+            js/artifacts/${{ steps.prepare_templates_nunjucks_artifact.outputs.packed_nunjucks_tarball }}
           retention-days: 1
 
   api-compatibility:
@@ -210,8 +231,15 @@ jobs:
         working-directory: js/smoke
         shell: bash
         run: |
-          # Use the same auto-discovery logic as the Makefile
-          SCENARIOS=$(command find scenarios -mindepth 1 -maxdepth 1 -type d -exec test -f {}/Makefile \; -print | sed 's|scenarios/||' | sort | jq -R -s -c 'split("\n") | map(select(length > 0))')
+          echo "Discovering local and integration scenarios..."
+          SCRIPTDIR="../../integrations"
+          # Local scenarios (under js/smoke/scenarios): emit their directory names
+          LOCAL=$(find scenarios -mindepth 1 -maxdepth 1 -type d -exec test -f {}/Makefile \; -print | sed 's|scenarios/||' | tr '\n' ' ')
+          # Integration scenarios: emit as integration/name
+          INTEGRATIONS=$(find "$SCRIPTDIR" -type f -path '*/smoke/scenarios/*/Makefile' 2>/dev/null | sed "s|^$SCRIPTDIR/||" | sed 's|/Makefile$||' | sed 's|/smoke/scenarios/|/|' | tr '\n' ' ')
+          ALL="${LOCAL} ${INTEGRATIONS}"
+          # Convert space-separated list to JSON array
+          SCENARIOS=$(printf "%s\n" $ALL | jq -R -s -c 'split("\n") | map(select(length>0))')
           echo "scenarios=$SCENARIOS" >> "$GITHUB_OUTPUT"
           echo "Discovered scenarios: $SCENARIOS"
 
@@ -255,6 +283,15 @@ jobs:
             fi
           done
 
+          # Copy browser tarball to well-known path
+          for f in braintrust-browser-[0-9]*.tgz; do
+            if [ -f "$f" ]; then
+              cp "$f" braintrust-browser-latest.tgz
+              echo "Copied $f to braintrust-browser-latest.tgz"
+              break
+            fi
+          done
+
           # Copy otel tarball to well-known path
           for f in braintrust-otel-[0-9]*.tgz; do
             if [ -f "$f" ]; then
@@ -264,6 +301,15 @@ jobs:
             fi
           done
 
+          # Copy templates-nunjucks-js tarball to well-known path
+          for f in braintrust-templates-nunjucks-js-[0-9]*.tgz; do
+            if [ -f "$f" ]; then
+              cp "$f" braintrust-templates-nunjucks-js-latest.tgz
+              echo "Copied $f to braintrust-templates-nunjucks-js-latest.tgz"
+              break
+            fi
+          done
+
       - name: Build shared test package (once for all scenarios)
         working-directory: js/smoke/shared
         shell: bash
@@ -278,7 +324,9 @@ jobs:
           BRAINTRUST_API_KEY: ${{ secrets.BRAINTRUST_API_KEY }}
           CI: true
           BRAINTRUST_TAR: ../artifacts/braintrust-latest.tgz
+          BRAINTRUST_BROWSER_TAR: ../artifacts/braintrust-browser-latest.tgz
           BRAINTRUST_OTEL_TAR: ../artifacts/braintrust-otel-latest.tgz
+          BRAINTRUST_TEMPLATES_NUNJUCKS_JS_TAR: ../artifacts/braintrust-templates-nunjucks-js-latest.tgz
           SMOKE_V2_SHARED_DIST: shared/dist
         run: |
           make test ${{ matrix.scenario }}
diff --git a/.github/workflows/templates-nunjucks-build-test.yaml b/.github/workflows/templates-nunjucks-build-test.yaml
new file mode 100644
index 000000000..ea48d56b3
--- /dev/null
+++ b/.github/workflows/templates-nunjucks-build-test.yaml
@@ -0,0 +1,46 @@
+name: templates-nunjucks-js
+
+on:
+  pull_request:
+    paths:
+      - "integrations/templates-nunjucks/**"
+      - "js/**"
+      - ".github/workflows/templates-nunjucks-build-test.yaml"
+  push:
+    branches: [main]
+    paths:
+      - "integrations/templates-nunjucks/**"
+      - "js/**"
+
+jobs:
+  build-and-test:
+    runs-on: ubuntu-latest
+
+    strategy:
+      fail-fast: false
+      matrix:
+        node-version: [20, 22]
+
+    steps:
+      - uses: actions/checkout@v4
+
+      - uses: actions/setup-node@v4
+        with:
+          node-version: ${{ matrix.node-version }}
+
+      - uses: pnpm/action-setup@v4
+
+      - name: Install dependencies
+        run: pnpm install --frozen-lockfile
+
+      - name: Build braintrust
+        working-directory: js
+        run: pnpm run build
+
+      - name: Build @braintrust/templates-nunjucks-js
+        working-directory: integrations/templates-nunjucks
+        run: pnpm run build
+
+      - name: Run @braintrust/templates-nunjucks-js tests
+        working-directory: integrations/templates-nunjucks
+        run: pnpm run test
diff --git a/Makefile b/Makefile
index 71a4182f6..162b8871e 100644
--- a/Makefile
+++ b/Makefile
@@ -63,7 +63,8 @@ js-build:
 	pnpm run build
 
 js-test: js-build
-	pnpm run test
+	# Run tests only for the JS workspace packages and exclude integration scenario tests
+	pnpm --filter ./js... run test
 	cd js && make test
 
 js-docs: js-build
diff --git a/integrations/browser-js/README.md b/integrations/browser-js/README.md
new file mode 100644
index 000000000..929c68553
--- /dev/null
+++ b/integrations/browser-js/README.md
@@ -0,0 +1,75 @@
+# Braintrust Browser SDK
+
+Official browser-only SDK for [Braintrust](https://braintrust.dev).
+
+This is an integration package that provides browser-optimized builds of the Braintrust SDK with AsyncLocalStorage polyfill support for standard browsers.
+
+## Installation
+
+```bash
+npm install @braintrust/browser braintrust
+# or
+pnpm add @braintrust/browser braintrust
+# or
+yarn add @braintrust/browser braintrust
+```
+
+Note: `braintrust` is a peer dependency and must be installed alongside `@braintrust/browser`.
+
+## Usage
+
+```typescript
+import * as braintrust from "@braintrust/browser";
+
+const experiment = await braintrust.init("BrowserExperiment", {
+  apiKey: "YOUR_API_KEY",
+});
+
+// Use tracing in browser
+const result = await braintrust.traced(
+  async () => {
+    // Your code here
+    return "result";
+  },
+  { name: "myOperation" },
+);
+```
+
+## Differences from Main Package
+
+This package:
+
+- **Includes** `als-browser` polyfill for AsyncLocalStorage (bundled)
+- **Requires** `braintrust` as a peer dependency
+
+## When to Use
+
+Use `@braintrust/browser` when:
+
+- Building browser-only applications
+- Need AsyncLocalStorage support in standard browsers
+
+Use `braintrust` directly when:
+
+- Building Node.js applications
+- Using in Next.js or other full-stack frameworks (with proper module resolution)
+- Need CLI tools or filesystem access
+
+## Features
+
+All browser-compatible features from the main SDK:
+
+- Logging and tracing
+- Experiments and datasets
+- Prompt management
+- AI provider wrappers (OpenAI, Anthropic, Google)
+- Evaluation framework
+- OpenTelemetry integration
+
+## Documentation
+
+For full documentation, visit [https://www.braintrust.dev/docs](https://www.braintrust.dev/docs)
+
+## License
+
+Apache-2.0
diff --git a/integrations/browser-js/package.json b/integrations/browser-js/package.json
new file mode 100644
index 000000000..aa4485367
--- /dev/null
+++ b/integrations/browser-js/package.json
@@ -0,0 +1,58 @@
+{
+  "name": "@braintrust/browser",
+  "version": "0.0.2",
+  "description": "Braintrust SDK for browser environments with AsyncLocalStorage polyfill",
+  "type": "module",
+  "module": "./dist/index.js",
+  "types": "./dist/index.d.ts",
+  "exports": {
+    ".": {
+      "types": "./dist/index.d.ts",
+      "import": "./dist/index.js",
+      "default": "./dist/index.js"
+    }
+  },
+  "files": [
+    "dist",
+    "README.md"
+  ],
+  "scripts": {
+    "build": "tsup",
+    "watch": "tsup --watch",
+    "clean": "rm -rf dist",
+    "test": "vitest run"
+  },
+  "dependencies": {
+    "als-browser": "^1.0.1"
+  },
+  "devDependencies": {
+    "@types/node": "^20.10.5",
+    "braintrust": "workspace:*",
+    "tsup": "^8.3.5",
+    "typescript": "^5.3.3",
+    "vitest": "^2.1.9"
+  },
+  "peerDependencies": {
+    "braintrust": ">=3.0.0",
+    "zod": "^3.25.34 || ^4.0"
+  },
+  "peerDependenciesMeta": {
+    "braintrust": {
+      "optional": false
+    },
+    "zod": {
+      "optional": false
+    }
+  },
+  "repository": {
+    "type": "git",
+    "url": "git+https://github.com/braintrustdata/braintrust-sdk.git",
+    "directory": "sdk/integrations/browser-js"
+  },
+  "homepage": "https://www.braintrust.dev/docs",
+  "license": "Apache-2.0",
+  "publishConfig": {
+    "access": "public",
+    "registry": "https://registry.npmjs.org/"
+  }
+}
diff --git a/integrations/browser-js/src/browser-config.ts b/integrations/browser-js/src/browser-config.ts
new file mode 100644
index 000000000..139cc3d90
--- /dev/null
+++ b/integrations/browser-js/src/browser-config.ts
@@ -0,0 +1,48 @@
+import { _internalIso as iso, _internalSetInitialState } from "braintrust";
+import { AsyncLocalStorage as BrowserAsyncLocalStorage } from "als-browser";
+
+let browserConfigured = false;
+
+export function configureBrowser() {
+  if (browserConfigured) {
+    return;
+  }
+
+  // Set build type indicator
+  iso.buildType = "browser";
+
+  iso.newAsyncLocalStorage = <T>() => new BrowserAsyncLocalStorage<T>();
+
+  iso.getEnv = (name: string) => {
+    if (typeof process === "undefined" || typeof process.env === "undefined") {
+      return undefined;
+    }
+    return process.env[name];
+  };
+
+  // noop implementations for git config
+  iso.getRepoInfo = async () => ({
+    commit: null,
+    branch: null,
+    tag: null,
+    dirty: false,
+  });
+  iso.getCallerLocation = () => undefined;
+
+  // Implement browser-compatible hash function using a simple hash algorithm
+  iso.hash = (data: string): string => {
+    // Simple hash function for browser compatibility
+    let hash = 0;
+    for (let i = 0; i < data.length; i++) {
+      const char = data.charCodeAt(i);
+      hash = (hash << 5) - hash + char;
+      hash = hash & hash; // Convert to 32bit integer
+    }
+    // Convert to hex string
+    const hashHex = (hash >>> 0).toString(16).padStart(8, "0");
+    return hashHex.repeat(8).substring(0, 64); // Make it look like a SHA-256 hash length
+  };
+
+  _internalSetInitialState();
+  browserConfigured = true;
+}
diff --git a/integrations/browser-js/src/index.ts b/integrations/browser-js/src/index.ts
new file mode 100644
index 000000000..70b350745
--- /dev/null
+++ b/integrations/browser-js/src/index.ts
@@ -0,0 +1,5 @@
+import { configureBrowser } from "./browser-config";
+
+configureBrowser();
+
+export * from "braintrust";
diff --git a/integrations/browser-js/tsconfig.json b/integrations/browser-js/tsconfig.json
new file mode 100644
index 000000000..94649b1d8
--- /dev/null
+++ b/integrations/browser-js/tsconfig.json
@@ -0,0 +1,15 @@
+{
+  "compilerOptions": {
+    "declaration": true,
+    "lib": ["es2022", "dom"],
+    "module": "esnext",
+    "target": "es2022",
+    "moduleResolution": "bundler",
+    "strict": true,
+    "esModuleInterop": true,
+    "skipLibCheck": true,
+    "resolveJsonModule": true
+  },
+  "include": ["src/**/*"],
+  "exclude": ["node_modules", "dist"]
+}
diff --git a/integrations/browser-js/tsup.config.ts b/integrations/browser-js/tsup.config.ts
new file mode 100644
index 000000000..b532d4d5c
--- /dev/null
+++ b/integrations/browser-js/tsup.config.ts
@@ -0,0 +1,14 @@
+import { defineConfig } from "tsup";
+
+export default defineConfig({
+  entry: ["src/index.ts"],
+  format: ["esm"],
+  dts: true,
+  sourcemap: true,
+  clean: true,
+  external: ["braintrust", "zod"],
+  target: "es2022",
+  platform: "browser",
+  outDir: "./dist",
+  treeshake: true,
+});
diff --git a/integrations/browser-js/turbo.json b/integrations/browser-js/turbo.json
new file mode 100644
index 000000000..6b90853c5
--- /dev/null
+++ b/integrations/browser-js/turbo.json
@@ -0,0 +1,10 @@
+{
+  "$schema": "https://turbo.build/schema.json",
+  "extends": ["//"],
+  "tasks": {
+    "build": {
+      "dependsOn": ["braintrust#build"],
+      "outputs": ["dist/**"]
+    }
+  }
+}
diff --git a/integrations/browser-js/vitest.config.ts b/integrations/browser-js/vitest.config.ts
new file mode 100644
index 000000000..73a26a648
--- /dev/null
+++ b/integrations/browser-js/vitest.config.ts
@@ -0,0 +1,7 @@
+import { defineConfig } from "vitest/config";
+
+export default defineConfig({
+  test: {
+    include: ["tests/**/*.test.ts", "src/**/*.test.ts"],
+  },
+});
diff --git a/integrations/langchain-js/vitest.config.ts b/integrations/langchain-js/vitest.config.ts
index 197422ec0..d16bcb8cc 100644
--- a/integrations/langchain-js/vitest.config.ts
+++ b/integrations/langchain-js/vitest.config.ts
@@ -3,5 +3,6 @@ import { defineConfig } from "vitest/config";
 export default defineConfig({
   test: {
     setupFiles: ["./src/test/setup.ts"],
+    include: ["tests/**/*.test.ts", "src/**/*.test.ts"],
   },
 });
diff --git a/integrations/openai-agents-js/src/index.ts b/integrations/openai-agents-js/src/index.ts
index 95a18edd5..4a6a565d3 100644
--- a/integrations/openai-agents-js/src/index.ts
+++ b/integrations/openai-agents-js/src/index.ts
@@ -382,7 +382,8 @@ export class OpenAIAgentsTraceProcessor {
       if (!data.metrics.completion_tokens && usage.completionTokens)
         data.metrics.completion_tokens = usage.completionTokens;
       if (usage.input_tokens_details?.cached_tokens != null)
-        data.metrics.prompt_cached_tokens = usage.input_tokens_details.cached_tokens;
+        data.metrics.prompt_cached_tokens =
+          usage.input_tokens_details.cached_tokens;
     }
 
     return data;
diff --git a/integrations/openai-agents-js/src/openai-agents-integration.test.ts b/integrations/openai-agents-js/src/openai-agents-integration.test.ts
index 618da167b..75c954942 100644
--- a/integrations/openai-agents-js/src/openai-agents-integration.test.ts
+++ b/integrations/openai-agents-js/src/openai-agents-integration.test.ts
@@ -908,7 +908,7 @@ describe(
               output_tokens: 50,
               total_tokens: 150,
               input_tokens_details: {
-                cached_tokens: 80,  // check for this later
+                cached_tokens: 80, // check for this later
               },
             },
           },
@@ -934,9 +934,17 @@ describe(
       const metrics = (responseSpanLog as any).metrics;
       assert.ok(metrics, "Response span should have metrics");
       assert.equal(metrics.prompt_tokens, 100, "Should have prompt_tokens");
-      assert.equal(metrics.completion_tokens, 50, "Should have completion_tokens");
+      assert.equal(
+        metrics.completion_tokens,
+        50,
+        "Should have completion_tokens",
+      );
       assert.equal(metrics.tokens, 150, "Should have total tokens");
-      assert.equal(metrics.prompt_cached_tokens, 80, "Should extract cached_tokens to prompt_cached_tokens");
+      assert.equal(
+        metrics.prompt_cached_tokens,
+        80,
+        "Should extract cached_tokens to prompt_cached_tokens",
+      );
     });
 
     test("Response span handles zero cached tokens correctly", async () => {
@@ -965,7 +973,7 @@ describe(
               input_tokens: 100,
               output_tokens: 50,
               input_tokens_details: {
-                cached_tokens: 0,  // Zero is a valid value
+                cached_tokens: 0, // Zero is a valid value
               },
             },
           },
@@ -977,7 +985,9 @@ describe(
       await processor.onSpanEnd(responseSpan);
 
       const spans = await backgroundLogger.drain();
-      const responseSpanLog = spans.find((s: any) => s.span_attributes?.type === "llm");
+      const responseSpanLog = spans.find(
+        (s: any) => s.span_attributes?.type === "llm",
+      );
       const metrics = (responseSpanLog as any).metrics;
 
       // Zero should be logged, not skipped
@@ -1024,11 +1034,16 @@ describe(
       await processor.onSpanEnd(responseSpan);
 
       const spans = await backgroundLogger.drain();
-      const responseSpanLog = spans.find((s: any) => s.span_attributes?.type === "llm");
+      const responseSpanLog = spans.find(
+        (s: any) => s.span_attributes?.type === "llm",
+      );
       const metrics = (responseSpanLog as any).metrics;
 
       // Should not have prompt_cached_tokens if not present in usage
-      assert.isUndefined(metrics.prompt_cached_tokens, "Should not add prompt_cached_tokens if not in usage");
+      assert.isUndefined(
+        metrics.prompt_cached_tokens,
+        "Should not add prompt_cached_tokens if not in usage",
+      );
     });
 
     test("Generation span extracts cached tokens from usage", async () => {
@@ -1060,7 +1075,7 @@ describe(
             output_tokens: 75,
             total_tokens: 275,
             input_tokens_details: {
-              cached_tokens: 150,  // Test Generation span extraction
+              cached_tokens: 150, // Test Generation span extraction
             },
           },
         },
@@ -1080,8 +1095,16 @@ describe(
       const metrics = (generationSpanLog as any).metrics;
       assert.ok(metrics, "Generation span should have metrics");
       assert.equal(metrics.prompt_tokens, 200, "Should have prompt_tokens");
-      assert.equal(metrics.completion_tokens, 75, "Should have completion_tokens");
-      assert.equal(metrics.prompt_cached_tokens, 150, "Should extract cached_tokens from Generation span");
+      assert.equal(
+        metrics.completion_tokens,
+        75,
+        "Should have completion_tokens",
+      );
+      assert.equal(
+        metrics.prompt_cached_tokens,
+        150,
+        "Should extract cached_tokens from Generation span",
+      );
     });
   },
 );
diff --git a/integrations/openai-agents-js/vitest.config.ts b/integrations/openai-agents-js/vitest.config.ts
index be2185492..8e30c5974 100644
--- a/integrations/openai-agents-js/vitest.config.ts
+++ b/integrations/openai-agents-js/vitest.config.ts
@@ -2,6 +2,7 @@ import { defineConfig } from "vitest/config";
 
 export default defineConfig({
   test: {
+    include: ["tests/**/*.test.ts", "src/**/*.test.ts"],
     // Add any specific test configuration if needed
   },
 });
diff --git a/integrations/otel-js/otel-v1/vitest.config.ts b/integrations/otel-js/otel-v1/vitest.config.ts
index 8c8114c32..fd400cc49 100644
--- a/integrations/otel-js/otel-v1/vitest.config.ts
+++ b/integrations/otel-js/otel-v1/vitest.config.ts
@@ -17,4 +17,7 @@ export default defineConfig({
           alias: createOtelAliases(cwd),
         }
       : {},
+  test: {
+    include: ["tests/**/*.test.ts", "src/**/*.test.ts"],
+  },
 });
diff --git a/integrations/otel-js/otel-v2/vitest.config.ts b/integrations/otel-js/otel-v2/vitest.config.ts
index 8c8114c32..fd400cc49 100644
--- a/integrations/otel-js/otel-v2/vitest.config.ts
+++ b/integrations/otel-js/otel-v2/vitest.config.ts
@@ -17,4 +17,7 @@ export default defineConfig({
           alias: createOtelAliases(cwd),
         }
       : {},
+  test: {
+    include: ["tests/**/*.test.ts", "src/**/*.test.ts"],
+  },
 });
diff --git a/js/smoke/scenarios/otel-v1/.gitignore b/integrations/otel-js/smoke/scenarios/otel-v1/.gitignore
similarity index 100%
rename from js/smoke/scenarios/otel-v1/.gitignore
rename to integrations/otel-js/smoke/scenarios/otel-v1/.gitignore
diff --git a/js/smoke/scenarios/otel-v1/Makefile b/integrations/otel-js/smoke/scenarios/otel-v1/Makefile
similarity index 78%
rename from js/smoke/scenarios/otel-v1/Makefile
rename to integrations/otel-js/smoke/scenarios/otel-v1/Makefile
index 0b72d0207..83e3338f5 100644
--- a/js/smoke/scenarios/otel-v1/Makefile
+++ b/integrations/otel-js/smoke/scenarios/otel-v1/Makefile
@@ -13,7 +13,7 @@ setup:
 		echo "==> Using BRAINTRUST_TAR: $(BRAINTRUST_TAR)"; \
 	else \
 		echo "==> Building SDK"; \
-		cd ../../.. && pnpm exec turbo build --filter=braintrust && mkdir -p artifacts && pnpm pack --pack-destination artifacts; \
+		cd ../../../.. && pnpm exec turbo build --filter=braintrust && mkdir -p artifacts && pnpm pack --pack-destination artifacts; \
 		\
 		for f in artifacts/braintrust-*.tgz; do \
 			if [ "$$(basename $$f)" != "braintrust-latest.tgz" ] && \
@@ -27,7 +27,7 @@ setup:
 	@# Build shared package (if not running from parent)
 	@if [ -z "$(SMOKE_V2_SHARED_DIST)" ]; then \
 		echo "==> Building shared package"; \
-		cd ../../shared && npm ci && npm run build; \
+		cd ../../../shared && npm ci && npm run build; \
 	fi
 
 	@# Check if BRAINTRUST_OTEL_TAR is set (from parent or CI), otherwise build
@@ -35,11 +35,11 @@ setup:
 		echo "==> Using BRAINTRUST_OTEL_TAR: $(BRAINTRUST_OTEL_TAR)"; \
 	else \
 		echo "==> Building @braintrust/otel package"; \
-		cd ../../../../integrations/otel-js && pnpm exec turbo build --filter=@braintrust/otel && pnpm pack --pack-destination ../../js/artifacts; \
+		cd ../../../../../integrations/otel-js && pnpm exec turbo build --filter=@braintrust/otel && pnpm pack --pack-destination ../../js/artifacts; \
 		\
-		for f in ../../js/artifacts/braintrust-otel-*.tgz; do \
+		for f in ../../../js/artifacts/braintrust-otel-*.tgz; do \
 			if [ "$$(basename $$f)" != "braintrust-otel-latest.tgz" ]; then \
-				cp "$$f" ../../js/artifacts/braintrust-otel-latest.tgz; \
+				cp "$$f" ../../../js/artifacts/braintrust-otel-latest.tgz; \
 				break; \
 			fi; \
 		done; \
diff --git a/js/smoke/scenarios/otel-v1/README.md b/integrations/otel-js/smoke/scenarios/otel-v1/README.md
similarity index 100%
rename from js/smoke/scenarios/otel-v1/README.md
rename to integrations/otel-js/smoke/scenarios/otel-v1/README.md
diff --git a/js/smoke/scenarios/otel-v1/mise.toml b/integrations/otel-js/smoke/scenarios/otel-v1/mise.toml
similarity index 100%
rename from js/smoke/scenarios/otel-v1/mise.toml
rename to integrations/otel-js/smoke/scenarios/otel-v1/mise.toml
diff --git a/js/smoke/scenarios/otel-v1/package.json b/integrations/otel-js/smoke/scenarios/otel-v1/package.json
similarity index 73%
rename from js/smoke/scenarios/otel-v1/package.json
rename to integrations/otel-js/smoke/scenarios/otel-v1/package.json
index 335a0b33b..50b0a8700 100644
--- a/js/smoke/scenarios/otel-v1/package.json
+++ b/integrations/otel-js/smoke/scenarios/otel-v1/package.json
@@ -3,8 +3,8 @@
   "private": true,
   "type": "module",
   "dependencies": {
-    "braintrust": "file:../../../artifacts/braintrust-latest.tgz",
-    "@braintrust/otel": "file:../../../artifacts/braintrust-otel-latest.tgz",
+    "braintrust": "file:../../../../../js/artifacts/braintrust-latest.tgz",
+    "@braintrust/otel": "file:../../../../../js/artifacts/braintrust-otel-latest.tgz",
     "@opentelemetry/api": "^1.9.0",
     "@opentelemetry/core": "^1.9.0",
     "@opentelemetry/exporter-trace-otlp-http": "^0.53.0",
diff --git a/js/smoke/scenarios/otel-v1/src/test-helpers.ts b/integrations/otel-js/smoke/scenarios/otel-v1/src/test-helpers.ts
similarity index 100%
rename from js/smoke/scenarios/otel-v1/src/test-helpers.ts
rename to integrations/otel-js/smoke/scenarios/otel-v1/src/test-helpers.ts
diff --git a/js/smoke/scenarios/otel-v1/tests/basic.test.ts b/integrations/otel-js/smoke/scenarios/otel-v1/tests/basic.test.ts
similarity index 97%
rename from js/smoke/scenarios/otel-v1/tests/basic.test.ts
rename to integrations/otel-js/smoke/scenarios/otel-v1/tests/basic.test.ts
index 2031df34d..8ae35e369 100644
--- a/js/smoke/scenarios/otel-v1/tests/basic.test.ts
+++ b/integrations/otel-js/smoke/scenarios/otel-v1/tests/basic.test.ts
@@ -8,7 +8,7 @@ import {
   displayTestResults,
   hasFailures,
   type TestResult,
-} from "../../../shared/dist/index.mjs";
+} from "../../../../../../js/smoke/shared/dist/index.mjs";
 
 async function main() {
   const results: TestResult[] = [];
diff --git a/js/smoke/scenarios/otel-v1/tests/filtering.test.ts b/integrations/otel-js/smoke/scenarios/otel-v1/tests/filtering.test.ts
similarity index 98%
rename from js/smoke/scenarios/otel-v1/tests/filtering.test.ts
rename to integrations/otel-js/smoke/scenarios/otel-v1/tests/filtering.test.ts
index 3fdfab0a4..0a7cf10a9 100644
--- a/js/smoke/scenarios/otel-v1/tests/filtering.test.ts
+++ b/integrations/otel-js/smoke/scenarios/otel-v1/tests/filtering.test.ts
@@ -8,7 +8,7 @@ import {
   displayTestResults,
   hasFailures,
   type TestResult,
-} from "../../../shared/dist/index.mjs";
+} from "../../../../../../js/smoke/shared/dist/index.mjs";
 
 type OtelPayload = {
   resourceSpans?: Array<{
diff --git a/js/smoke/scenarios/otel-v1/tests/shared-suite.test.ts b/integrations/otel-js/smoke/scenarios/otel-v1/tests/shared-suite.test.ts
similarity index 80%
rename from js/smoke/scenarios/otel-v1/tests/shared-suite.test.ts
rename to integrations/otel-js/smoke/scenarios/otel-v1/tests/shared-suite.test.ts
index 5559e89ac..83fba976f 100644
--- a/js/smoke/scenarios/otel-v1/tests/shared-suite.test.ts
+++ b/integrations/otel-js/smoke/scenarios/otel-v1/tests/shared-suite.test.ts
@@ -4,6 +4,7 @@
 
 import {
   runTests,
+  expectFailure,
   testBasicSpanLogging,
   testMultipleSpans,
   testDirectLogging,
@@ -25,7 +26,10 @@ import {
   testTestingExports,
   testStateManagementExports,
   testBuildResolution,
-} from "../../../shared/dist/index.js";
+  testMustacheTemplate,
+  testNunjucksTemplate,
+  testEvalSmoke,
+} from "../../../../../../js/smoke/shared/dist/index.js";
 
 async function runSharedTestSuites() {
   const braintrust = await import("braintrust");
@@ -55,6 +59,14 @@ async function runSharedTestSuites() {
       testAsyncLocalStorageTraced,
       testNestedTraced,
       testCurrentSpan,
+      testEvalSmoke,
+      testMustacheTemplate,
+      expectFailure(
+        testNunjucksTemplate,
+        (e: { message: string }) =>
+          e.message.includes("requires @braintrust/template-nunjucks"),
+        "Nunjucks requires separate package",
+      ),
     ],
   });
 
diff --git a/js/smoke/scenarios/otel-v1/tsconfig.json b/integrations/otel-js/smoke/scenarios/otel-v1/tsconfig.json
similarity index 100%
rename from js/smoke/scenarios/otel-v1/tsconfig.json
rename to integrations/otel-js/smoke/scenarios/otel-v1/tsconfig.json
diff --git a/integrations/otel-js/vitest.config.ts b/integrations/otel-js/vitest.config.ts
index 8fb6f2dcf..73a26a648 100644
--- a/integrations/otel-js/vitest.config.ts
+++ b/integrations/otel-js/vitest.config.ts
@@ -1,3 +1,7 @@
 import { defineConfig } from "vitest/config";
 
-export default defineConfig({});
+export default defineConfig({
+  test: {
+    include: ["tests/**/*.test.ts", "src/**/*.test.ts"],
+  },
+});
diff --git a/integrations/templates-nunjucks/package.json b/integrations/templates-nunjucks/package.json
new file mode 100644
index 000000000..71c0a490b
--- /dev/null
+++ b/integrations/templates-nunjucks/package.json
@@ -0,0 +1,42 @@
+{
+  "name": "@braintrust/templates-nunjucks-js",
+  "version": "0.0.1",
+  "description": "Nunjucks templating support for the Braintrust JS SDK",
+  "main": "./dist/index.js",
+  "module": "./dist/index.mjs",
+  "types": "./dist/index.d.ts",
+  "exports": {
+    "./package.json": "./package.json",
+    ".": {
+      "types": "./dist/index.d.ts",
+      "import": "./dist/index.mjs",
+      "module": "./dist/index.mjs",
+      "require": "./dist/index.js"
+    }
+  },
+  "files": [
+    "dist/**/*"
+  ],
+  "scripts": {
+    "build": "tsup",
+    "watch": "tsup --watch",
+    "clean": "rm -r dist/*",
+    "test": "vitest run --exclude 'smoke/scenarios/**'"
+  },
+  "author": "Braintrust Data Inc.",
+  "license": "Apache-2.0",
+  "dependencies": {
+    "nunjucks": "^3.2.4"
+  },
+  "peerDependencies": {
+    "braintrust": ">=3.0.0"
+  },
+  "devDependencies": {
+    "@types/nunjucks": "^3.2.6",
+    "@types/node": "^20.10.5",
+    "braintrust": "workspace:*",
+    "tsup": "^8.5.1",
+    "typescript": "5.5.4",
+    "vitest": "^2.1.9"
+  }
+}
diff --git a/integrations/templates-nunjucks/smoke/scenarios/deno-node/Makefile b/integrations/templates-nunjucks/smoke/scenarios/deno-node/Makefile
new file mode 100644
index 000000000..92a53564b
--- /dev/null
+++ b/integrations/templates-nunjucks/smoke/scenarios/deno-node/Makefile
@@ -0,0 +1,37 @@
+.PHONY: setup test
+
+setup:
+	@echo "==> Setting up templates-nunjucks deno scenario"
+	mise install
+
+	@# Build or extract braintrust SDK (workspace link will use dist/)
+	@if [ -n "$(BRAINTRUST_TAR)" ]; then \
+		echo "==> Extracting SDK tarball for workspace link"; \
+		TARBALL_PATH="$$(cd ../../../../../js/smoke && pwd)/$(BRAINTRUST_TAR)"; \
+		echo "==> Resolved tarball path: $$TARBALL_PATH"; \
+		cd ../../../../../js && tar -xzf "$$TARBALL_PATH" --strip-components=1 package/dist; \
+	else \
+		echo "==> Building SDK"; \
+		cd ../../../../../js && pnpm build; \
+	fi
+
+	@# Build or extract @braintrust/templates-nunjucks-js (workspace link will use dist/)
+	@if [ -n "$(BRAINTRUST_TEMPLATES_NUNJUCKS_JS_TAR)" ]; then \
+		echo "==> Extracting templates-nunjucks tarball for workspace link"; \
+		TARBALL_PATH="$$(cd ../../../../../js/smoke && pwd)/$(BRAINTRUST_TEMPLATES_NUNJUCKS_JS_TAR)"; \
+		echo "==> Resolved tarball path: $$TARBALL_PATH"; \
+		cd ../../.. && tar -xzf "$$TARBALL_PATH" --strip-components=1 package/dist; \
+	else \
+		echo "==> Building @braintrust/templates-nunjucks-js package"; \
+		cd ../../../../.. && pnpm install && pnpm --filter=@braintrust/templates-nunjucks-js build; \
+	fi
+
+	@# Build shared package (if not running from parent)
+	@if [ -z "$(SMOKE_V2_SHARED_DIST)" ]; then \
+		echo "==> Building shared package"; \
+		cd ../../../../../js/smoke/shared && npm install && npm run build; \
+	fi
+
+test: setup
+	@echo "==> Running deno tests"
+	mise exec -- deno test --no-check --sloppy-imports --allow-all tests/*.test.ts
diff --git a/integrations/templates-nunjucks/smoke/scenarios/deno-node/deno.json b/integrations/templates-nunjucks/smoke/scenarios/deno-node/deno.json
new file mode 100644
index 000000000..deba541b0
--- /dev/null
+++ b/integrations/templates-nunjucks/smoke/scenarios/deno-node/deno.json
@@ -0,0 +1,16 @@
+{
+  "imports": {
+    "@std/assert": "jsr:@std/assert@^1.0.14",
+    "@braintrust/smoke-test-shared": "jsr:@braintrust/smoke-test-shared",
+    "@braintrust/templates-nunjucks-js": "npm:@braintrust/templates-nunjucks-js",
+    "braintrust": "npm:braintrust",
+    "zod": "npm:zod@^4.2.1",
+    "zod/": "npm:/zod@^4.2.1/"
+  },
+  "nodeModulesDir": "auto",
+  "links": [
+    "../../../../../js",
+    "../../../",
+    "../../../../../js/smoke/shared"
+  ]
+}
diff --git a/integrations/templates-nunjucks/smoke/scenarios/deno-node/mise.toml b/integrations/templates-nunjucks/smoke/scenarios/deno-node/mise.toml
new file mode 100644
index 000000000..dd563ce6f
--- /dev/null
+++ b/integrations/templates-nunjucks/smoke/scenarios/deno-node/mise.toml
@@ -0,0 +1,3 @@
+[tools]
+deno = "latest"
+pnpm = "10.26.2"
diff --git a/integrations/templates-nunjucks/smoke/scenarios/deno-node/tests/shared-suite.test.ts b/integrations/templates-nunjucks/smoke/scenarios/deno-node/tests/shared-suite.test.ts
new file mode 100644
index 000000000..5800d3e6b
--- /dev/null
+++ b/integrations/templates-nunjucks/smoke/scenarios/deno-node/tests/shared-suite.test.ts
@@ -0,0 +1,27 @@
+// @ts-nocheck
+/**
+ * Templates-Nunjucks Deno smoke test - testing template rendering only
+ */
+
+import { assertEquals } from "@std/assert";
+import {
+  runTests,
+  testMustacheTemplate,
+  testNunjucksTemplate,
+} from "@braintrust/smoke-test-shared";
+import * as braintrust from "braintrust";
+import { nunjucksPlugin } from "@braintrust/templates-nunjucks-js";
+
+Deno.test("Run template tests with Nunjucks", async () => {
+  // Register nunjucks plugin before running tests
+  braintrust.registerTemplatePlugin(nunjucksPlugin);
+
+  const { failed } = await runTests({
+    name: "templates-nunjucks-deno",
+    braintrust,
+    tests: [testMustacheTemplate, testNunjucksTemplate],
+    skipCoverage: true,
+  });
+
+  assertEquals(failed.length, 0, "All template tests should pass");
+});
diff --git a/integrations/templates-nunjucks/smoke/scenarios/jest/Makefile b/integrations/templates-nunjucks/smoke/scenarios/jest/Makefile
new file mode 100644
index 000000000..29291218a
--- /dev/null
+++ b/integrations/templates-nunjucks/smoke/scenarios/jest/Makefile
@@ -0,0 +1,48 @@
+.PHONY: setup test
+
+setup:
+	@echo "==> Setting up templates-nunjucks jest scenario"
+	mise install
+
+	@# Build SDK and shared package if not provided
+	@if [ -n "$(BRAINTRUST_TAR)" ]; then \
+		echo "==> Using BRAINTRUST_TAR: $(BRAINTRUST_TAR)"; \
+	else \
+		echo "==> Building SDK"; \
+		cd ../../../../.. && pnpm exec turbo build --filter=braintrust && mkdir -p js/artifacts && pnpm --filter=braintrust pack --pack-destination js/artifacts; \
+		for f in js/artifacts/braintrust-*.tgz; do \
+			if [ "$$(basename $$f)" != "braintrust-latest.tgz" ] && \
+			   [ "$$(basename $$f)" != "braintrust-otel-latest.tgz" ] && \
+			   [ "$$(basename $$f)" != "braintrust-templates-nunjucks-js-latest.tgz" ]; then \
+				cp "$$f" js/artifacts/braintrust-latest.tgz; \
+				break; \
+			fi; \
+		done; \
+	fi
+
+	@# Build shared package (if not running from parent)
+	@if [ -z "$(SMOKE_V2_SHARED_DIST)" ]; then \
+		echo "==> Building shared package"; \
+		cd ../../../../../js/smoke/shared && npm install && npm run build; \
+	fi
+
+	@# Build @braintrust/templates-nunjucks-js package
+	@if [ -n "$(BRAINTRUST_TEMPLATES_NUNJUCKS_JS_TAR)" ]; then \
+		echo "==> Using BRAINTRUST_TEMPLATES_NUNJUCKS_JS_TAR: $(BRAINTRUST_TEMPLATES_NUNJUCKS_JS_TAR)"; \
+	else \
+		echo "==> Building @braintrust/templates-nunjucks-js package"; \
+		cd ../../../../.. && pnpm exec turbo build --filter=@braintrust/templates-nunjucks-js && cd integrations/templates-nunjucks && pnpm pack --pack-destination ../js/artifacts; \
+		for f in ../../js/artifacts/braintrust-templates-nunjucks-*.tgz; do \
+			if [ "$$(basename $$f)" != "braintrust-templates-nunjucks-js-latest.tgz" ]; then \
+				cp "$$f" ../../js/artifacts/braintrust-templates-nunjucks-js-latest.tgz; \
+				break; \
+			fi; \
+		done; \
+	fi
+
+	npm install --no-package-lock
+
+test: setup
+	@echo "==> Running jest tests"
+	@# Run only tests under the local tests/ directory to avoid workspace-wide discovery
+	npx jest --passWithNoTests --roots ./tests
diff --git a/integrations/templates-nunjucks/smoke/scenarios/jest/package.json b/integrations/templates-nunjucks/smoke/scenarios/jest/package.json
new file mode 100644
index 000000000..703b21d4d
--- /dev/null
+++ b/integrations/templates-nunjucks/smoke/scenarios/jest/package.json
@@ -0,0 +1,16 @@
+{
+  "name": "smoke-templates-nunjucks-jest",
+  "private": true,
+  "type": "commonjs",
+  "dependencies": {
+    "braintrust": "file:../../../../../js/artifacts/braintrust-latest.tgz",
+    "@braintrust/templates-nunjucks-js": "file:../../../../../js/artifacts/braintrust-templates-nunjucks-js-latest.tgz"
+  },
+  "devDependencies": {
+    "@types/jest": "^29.5.0",
+    "@types/node": "^20.10.5",
+    "jest": "^29.7.0",
+    "ts-jest": "^29.1.0",
+    "typescript": "^5.4.4"
+  }
+}
diff --git a/integrations/templates-nunjucks/smoke/scenarios/jest/tests/jest-basic.test.js b/integrations/templates-nunjucks/smoke/scenarios/jest/tests/jest-basic.test.js
new file mode 100644
index 000000000..98aa16d55
--- /dev/null
+++ b/integrations/templates-nunjucks/smoke/scenarios/jest/tests/jest-basic.test.js
@@ -0,0 +1,26 @@
+const {
+  runTests,
+  testMustacheTemplate,
+  testNunjucksTemplate,
+} = require("../../../../../../js/smoke/shared/dist/index.js");
+const braintrust = require("braintrust");
+const { nunjucksPlugin } = require("@braintrust/templates-nunjucks-js");
+
+test("Templates-Nunjucks basic behavior", async () => {
+  // Register nunjucks plugin before running tests
+  braintrust.registerTemplatePlugin(nunjucksPlugin);
+
+  const { failed } = await runTests({
+    name: "templates-nunjucks-jest",
+    braintrust,
+    tests: [testMustacheTemplate, testNunjucksTemplate],
+    skipCoverage: true,
+  });
+
+  if (failed.length > 0) {
+    const msg = failed
+      .map((f) => `${f.name}: ${f.error ?? "failed"}`)
+      .join("\n");
+    throw new Error(`Found failures:\n${msg}`);
+  }
+});
diff --git a/integrations/templates-nunjucks/smoke/scenarios/nextjs/.gitignore b/integrations/templates-nunjucks/smoke/scenarios/nextjs/.gitignore
new file mode 100644
index 000000000..a3f58edb0
--- /dev/null
+++ b/integrations/templates-nunjucks/smoke/scenarios/nextjs/.gitignore
@@ -0,0 +1,6 @@
+node_modules/
+.next/
+test-results/
+*.log
+.env.local
+package-lock.json
diff --git a/integrations/templates-nunjucks/smoke/scenarios/nextjs/Makefile b/integrations/templates-nunjucks/smoke/scenarios/nextjs/Makefile
new file mode 100644
index 000000000..3191aeadf
--- /dev/null
+++ b/integrations/templates-nunjucks/smoke/scenarios/nextjs/Makefile
@@ -0,0 +1,56 @@
+.PHONY: setup test
+
+setup:
+	@echo "==> Setting up templates-nunjucks nextjs scenario"
+	mise install
+
+	@# Build SDK and shared package if not provided
+	@if [ -n "$(BRAINTRUST_TAR)" ]; then \
+		echo "==> Using BRAINTRUST_TAR: $(BRAINTRUST_TAR)"; \
+	else \
+		echo "==> Building SDK"; \
+		cd ../../../../.. && pnpm exec turbo build --filter=braintrust && mkdir -p js/artifacts && pnpm --filter=braintrust pack --pack-destination js/artifacts; \
+		for f in js/artifacts/braintrust-*.tgz; do \
+			if [ "$$(basename $$f)" != "braintrust-latest.tgz" ] && \
+			   [ "$$(basename $$f)" != "braintrust-otel-latest.tgz" ] && \
+			   [ "$$(basename $$f)" != "braintrust-templates-nunjucks-js-latest.tgz" ]; then \
+				cp "$$f" js/artifacts/braintrust-latest.tgz; \
+				break; \
+			fi; \
+		done; \
+	fi
+
+	@# Build shared package (if not running from parent)
+	@if [ -z "$(SMOKE_V2_SHARED_DIST)" ]; then \
+		echo "==> Building shared package"; \
+		cd ../../../../../js/smoke/shared && npm install && npm run build; \
+	fi
+
+	@# Build @braintrust/templates-nunjucks-js package
+	@if [ -n "$(BRAINTRUST_TEMPLATES_NUNJUCKS_JS_TAR)" ]; then \
+		echo "==> Using BRAINTRUST_TEMPLATES_NUNJUCKS_JS_TAR: $(BRAINTRUST_TEMPLATES_NUNJUCKS_JS_TAR)"; \
+	else \
+		echo "==> Building @braintrust/templates-nunjucks-js package"; \
+		cd ../../../../.. && \
+		pnpm exec turbo build --filter=@braintrust/templates-nunjucks-js && \
+		cd integrations/templates-nunjucks && \
+		pnpm pack --pack-destination ../../js/artifacts && \
+		cd ../../js/artifacts && \
+		for f in braintrust-templates-nunjucks-*.tgz; do \
+			if [ "$$(basename $$f)" != "braintrust-templates-nunjucks-js-latest.tgz" ]; then \
+				cp "$$f" braintrust-templates-nunjucks-js-latest.tgz; \
+				break; \
+			fi; \
+		done; \
+	fi
+
+	@echo "==> Cleaning and reinstalling node_modules to pick up new tarballs"
+	rm -rf node_modules package-lock.json .next
+	npm install --no-package-lock
+
+test: setup
+	@echo "==> Running Next.js integration test"
+	@echo "==> Building Next.js app"
+	npx next build
+	@echo "==> Starting Next.js dev server and running Playwright tests"
+	npx playwright test
diff --git a/integrations/templates-nunjucks/smoke/scenarios/nextjs/next-env.d.ts b/integrations/templates-nunjucks/smoke/scenarios/nextjs/next-env.d.ts
new file mode 100644
index 000000000..830fb594c
--- /dev/null
+++ b/integrations/templates-nunjucks/smoke/scenarios/nextjs/next-env.d.ts
@@ -0,0 +1,6 @@
+/// <reference types="next" />
+/// <reference types="next/image-types/global" />
+/// <reference path="./.next/types/routes.d.ts" />
+
+// NOTE: This file should not be edited
+// see https://nextjs.org/docs/app/api-reference/config/typescript for more information.
diff --git a/integrations/templates-nunjucks/smoke/scenarios/nextjs/next.config.mjs b/integrations/templates-nunjucks/smoke/scenarios/nextjs/next.config.mjs
new file mode 100644
index 000000000..4678774e6
--- /dev/null
+++ b/integrations/templates-nunjucks/smoke/scenarios/nextjs/next.config.mjs
@@ -0,0 +1,4 @@
+/** @type {import('next').NextConfig} */
+const nextConfig = {};
+
+export default nextConfig;
diff --git a/integrations/templates-nunjucks/smoke/scenarios/nextjs/package.json b/integrations/templates-nunjucks/smoke/scenarios/nextjs/package.json
new file mode 100644
index 000000000..22c862740
--- /dev/null
+++ b/integrations/templates-nunjucks/smoke/scenarios/nextjs/package.json
@@ -0,0 +1,17 @@
+{
+  "name": "smoke-templates-nunjucks-nextjs",
+  "private": true,
+  "dependencies": {
+    "braintrust": "file:../../../../../js/artifacts/braintrust-latest.tgz",
+    "@braintrust/templates-nunjucks-js": "file:../../../../../js/artifacts/braintrust-templates-nunjucks-js-latest.tgz",
+    "next": "^15.1.4",
+    "react": "^19.0.0",
+    "react-dom": "^19.0.0"
+  },
+  "devDependencies": {
+    "@playwright/test": "^1.49.1",
+    "@types/node": "^20.11.5",
+    "@types/react": "^18.2.48",
+    "typescript": "^5.3.3"
+  }
+}
diff --git a/integrations/templates-nunjucks/smoke/scenarios/nextjs/playwright.config.mts b/integrations/templates-nunjucks/smoke/scenarios/nextjs/playwright.config.mts
new file mode 100644
index 000000000..ec75bdd0d
--- /dev/null
+++ b/integrations/templates-nunjucks/smoke/scenarios/nextjs/playwright.config.mts
@@ -0,0 +1,26 @@
+import { defineConfig, devices } from "@playwright/test";
+import path from "path";
+import { fileURLToPath } from "url";
+
+const __dirname = path.dirname(fileURLToPath(import.meta.url));
+
+export default defineConfig({
+  testDir: "./tests",
+  timeout: 30000,
+  webServer: {
+    command: "npx next dev --port 3456",
+    port: 3456,
+    cwd: __dirname,
+    timeout: 120000,
+    reuseExistingServer: !process.env.CI,
+  },
+  use: {
+    baseURL: "http://localhost:3456",
+  },
+  projects: [
+    {
+      name: "chromium",
+      use: { ...devices["Desktop Chrome"] },
+    },
+  ],
+});
diff --git a/integrations/templates-nunjucks/smoke/scenarios/nextjs/src/app/api/test/route.ts b/integrations/templates-nunjucks/smoke/scenarios/nextjs/src/app/api/test/route.ts
new file mode 100644
index 000000000..27827c73a
--- /dev/null
+++ b/integrations/templates-nunjucks/smoke/scenarios/nextjs/src/app/api/test/route.ts
@@ -0,0 +1,128 @@
+import { NextResponse } from "next/server";
+import { registerTemplatePlugin, Prompt } from "braintrust";
+import { nunjucksPlugin } from "@braintrust/templates-nunjucks-js";
+
+export const runtime = "nodejs";
+
+export async function GET() {
+  console.log("API route called - starting dynamic imports");
+  try {
+    registerTemplatePlugin(nunjucksPlugin);
+
+    const results = [];
+
+    // Test 1: Basic nunjucks template rendering
+    const prompt = new Prompt(
+      {
+        id: "test-prompt-1",
+        _xact_id: "test-xact",
+        project_id: "test-project",
+        name: "nunjucks-nextjs-test",
+        slug: "nunjucks-nextjs-test",
+        prompt_data: {
+          prompt: {
+            type: "chat",
+            messages: [
+              {
+                role: "user",
+                content:
+                  "Items: {% for item in items %}{{ item.name }}{% if not loop.last %}, {% endif %}{% endfor %}",
+              },
+            ],
+          },
+          options: { model: "gpt-4" },
+        },
+      },
+      {},
+      false,
+    );
+
+    const result = prompt.build(
+      { items: [{ name: "apple" }, { name: "banana" }, { name: "cherry" }] },
+      { templateFormat: "nunjucks" },
+    );
+    if (result.messages[0]?.content === "Items: apple, banana, cherry") {
+      results.push({
+        status: "pass",
+        name: "Nunjucks template loop rendering",
+      });
+    } else {
+      results.push({
+        status: "fail",
+        name: "Nunjucks template loop rendering",
+        error: {
+          message: `Expected "Items: apple, banana, cherry", got "${result.messages[0]?.content}"`,
+        },
+      });
+    }
+
+    // Test 2: Conditional rendering
+    const conditionalPrompt = new Prompt(
+      {
+        id: "test-prompt-2",
+        _xact_id: "test-xact",
+        project_id: "test-project",
+        name: "nunjucks-conditional-test",
+        slug: "nunjucks-conditional-test",
+        prompt_data: {
+          prompt: {
+            type: "chat",
+            messages: [
+              {
+                role: "user",
+                content:
+                  "{% if showGreeting %}Hello, {{ name }}!{% else %}Goodbye!{% endif %}",
+              },
+            ],
+          },
+          options: { model: "gpt-4" },
+        },
+      },
+      {},
+      false,
+    );
+
+    const conditionalResult = conditionalPrompt.build(
+      { showGreeting: true, name: "World" },
+      { templateFormat: "nunjucks" },
+    );
+
+    if (conditionalResult.messages[0]?.content === "Hello, World!") {
+      results.push({
+        status: "pass",
+        name: "Nunjucks conditional rendering",
+      });
+    } else {
+      results.push({
+        status: "fail",
+        name: "Nunjucks conditional rendering",
+        error: {
+          message: `Expected "Hello, World!", got "${conditionalResult.messages[0]?.content}"`,
+        },
+      });
+    }
+
+    const failures = results.filter((r) => r.status === "fail");
+
+    return NextResponse.json(
+      {
+        success: failures.length === 0,
+        message:
+          failures.length > 0
+            ? `${failures.length} test(s) failed`
+            : "All tests passed",
+        content: result.messages[0]?.content,
+        totalTests: results.length,
+        passedTests: results.filter((r) => r.status === "pass").length,
+        failedTests: failures.length,
+        results,
+      },
+      { status: failures.length === 0 ? 200 : 500 },
+    );
+  } catch (error) {
+    return NextResponse.json(
+      { success: false, error: String(error) },
+      { status: 500 },
+    );
+  }
+}
diff --git a/integrations/templates-nunjucks/smoke/scenarios/nextjs/src/app/layout.tsx b/integrations/templates-nunjucks/smoke/scenarios/nextjs/src/app/layout.tsx
new file mode 100644
index 000000000..225b6038d
--- /dev/null
+++ b/integrations/templates-nunjucks/smoke/scenarios/nextjs/src/app/layout.tsx
@@ -0,0 +1,11 @@
+export default function RootLayout({
+  children,
+}: {
+  children: React.ReactNode;
+}) {
+  return (
+    <html lang="en">
+      <body>{children}</body>
+    </html>
+  );
+}
diff --git a/integrations/templates-nunjucks/smoke/scenarios/nextjs/src/app/page.tsx b/integrations/templates-nunjucks/smoke/scenarios/nextjs/src/app/page.tsx
new file mode 100644
index 000000000..cfaa25088
--- /dev/null
+++ b/integrations/templates-nunjucks/smoke/scenarios/nextjs/src/app/page.tsx
@@ -0,0 +1,3 @@
+export default function Home() {
+  return <div>Templates-Nunjucks Next.js Test</div>;
+}
diff --git a/integrations/templates-nunjucks/smoke/scenarios/nextjs/tests/nextjs.test.ts b/integrations/templates-nunjucks/smoke/scenarios/nextjs/tests/nextjs.test.ts
new file mode 100644
index 000000000..e08fe5ee0
--- /dev/null
+++ b/integrations/templates-nunjucks/smoke/scenarios/nextjs/tests/nextjs.test.ts
@@ -0,0 +1,14 @@
+import { test, expect } from "@playwright/test";
+
+test("Nunjucks template rendering in Next.js API route", async ({
+  request,
+}) => {
+  const response = await request.get("/api/test");
+
+  const text = await response.text();
+  const data = JSON.parse(text);
+
+  expect(response.ok()).toBeTruthy();
+  expect(data.success).toBe(true);
+  expect(data.content).toBe("Items: apple, banana, cherry");
+});
diff --git a/integrations/templates-nunjucks/smoke/scenarios/nextjs/tsconfig.json b/integrations/templates-nunjucks/smoke/scenarios/nextjs/tsconfig.json
new file mode 100644
index 000000000..f619795e7
--- /dev/null
+++ b/integrations/templates-nunjucks/smoke/scenarios/nextjs/tsconfig.json
@@ -0,0 +1,35 @@
+{
+  "compilerOptions": {
+    "target": "ES2017",
+    "lib": [
+      "dom",
+      "dom.iterable",
+      "esnext"
+    ],
+    "allowJs": true,
+    "skipLibCheck": true,
+    "strict": false,
+    "noEmit": true,
+    "incremental": true,
+    "module": "esnext",
+    "esModuleInterop": true,
+    "moduleResolution": "node",
+    "resolveJsonModule": true,
+    "isolatedModules": true,
+    "jsx": "preserve",
+    "plugins": [
+      {
+        "name": "next"
+      }
+    ]
+  },
+  "include": [
+    "next-env.d.ts",
+    ".next/types/**/*.ts",
+    "**/*.ts",
+    "**/*.tsx"
+  ],
+  "exclude": [
+    "node_modules"
+  ]
+}
diff --git a/integrations/templates-nunjucks/smoke/scenarios/node-esm/Makefile b/integrations/templates-nunjucks/smoke/scenarios/node-esm/Makefile
new file mode 100644
index 000000000..4c705d23d
--- /dev/null
+++ b/integrations/templates-nunjucks/smoke/scenarios/node-esm/Makefile
@@ -0,0 +1,55 @@
+.PHONY: setup test
+
+# ============================================================================
+# Setup
+# ============================================================================
+
+setup:
+	@echo "==> Setting up templates-nunjucks scenario"
+	mise install
+
+	@# Check if BRAINTRUST_TAR is set (from parent or CI), otherwise build
+	@if [ -n "$(BRAINTRUST_TAR)" ]; then \
+		echo "==> Using BRAINTRUST_TAR: $(BRAINTRUST_TAR)"; \
+	else \
+		echo "==> Building SDK"; \
+		cd ../../../../.. && pnpm exec turbo build --filter=braintrust && mkdir -p js/artifacts && pnpm --filter=braintrust pack --pack-destination js/artifacts; \
+		for f in js/artifacts/braintrust-*.tgz; do \
+			if [ "$$(basename $$f)" != "braintrust-latest.tgz" ] && \
+			   [ "$$(basename $$f)" != "braintrust-otel-latest.tgz" ] && \
+			   [ "$$(basename $$f)" != "braintrust-templates-nunjucks-latest.tgz" ]; then \
+				cp "$$f" js/artifacts/braintrust-latest.tgz; \
+				break; \
+			fi; \
+		done; \
+	fi
+
+	@# Build shared package (if not running from parent)
+	@if [ -z "$(SMOKE_V2_SHARED_DIST)" ]; then \
+		echo "==> Building shared package"; \
+		cd ../../../../../js/smoke/shared && npm install && npm run build; \
+	fi
+
+	@# Build @braintrust/templates-nunjucks-js package into js/artifacts
+	@if [ -n "$(BRAINTRUST_TEMPLATES_NUNJUCKS_JS_TAR)" ]; then \
+		echo "==> Using BRAINTRUST_TEMPLATES_NUNJUCKS_JS_TAR: $(BRAINTRUST_TEMPLATES_NUNJUCKS_JS_TAR)"; \
+	else \
+		echo "==> Building @braintrust/templates-nunjucks-js package"; \
+		cd ../../../../.. && pnpm exec turbo build --filter=@braintrust/templates-nunjucks-js && cd integrations/templates-nunjucks && pnpm pack --pack-destination ../js/artifacts; \
+		for f in ../../js/artifacts/braintrust-templates-nunjucks-*.tgz; do \
+			if [ "$$(basename $$f)" != "braintrust-templates-nunjucks-js-latest.tgz" ]; then \
+				cp "$$f" ../../js/artifacts/braintrust-templates-nunjucks-js-latest.tgz; \
+				break; \
+			fi; \
+		done; \
+	fi
+
+	npm install --no-package-lock
+
+# ============================================================================
+# Test
+# ============================================================================
+
+test: setup
+	@echo "==> Running templates-nunjucks tests"
+	npx tsx tests/basic.test.ts
diff --git a/integrations/templates-nunjucks/smoke/scenarios/node-esm/package.json b/integrations/templates-nunjucks/smoke/scenarios/node-esm/package.json
new file mode 100644
index 000000000..942dfbbf5
--- /dev/null
+++ b/integrations/templates-nunjucks/smoke/scenarios/node-esm/package.json
@@ -0,0 +1,14 @@
+{
+  "name": "smoke-templates-nunjucks-integration",
+  "private": true,
+  "type": "module",
+  "dependencies": {
+    "braintrust": "file:../../../../../js/artifacts/braintrust-latest.tgz",
+    "@braintrust/templates-nunjucks-js": "file:../../../../../js/artifacts/braintrust-templates-nunjucks-js-latest.tgz"
+  },
+  "devDependencies": {
+    "@types/node": "^20.10.5",
+    "tsx": "^4.19.2",
+    "typescript": "^5.4.4"
+  }
+}
diff --git a/integrations/templates-nunjucks/smoke/scenarios/node-esm/tests/basic.test.ts b/integrations/templates-nunjucks/smoke/scenarios/node-esm/tests/basic.test.ts
new file mode 100644
index 000000000..0e53dce22
--- /dev/null
+++ b/integrations/templates-nunjucks/smoke/scenarios/node-esm/tests/basic.test.ts
@@ -0,0 +1,28 @@
+import {
+  runTests,
+  testMustacheTemplate,
+  testNunjucksTemplate,
+} from "../../../../../../js/smoke/shared/dist/index.mjs";
+import * as braintrust from "braintrust";
+import { nunjucksPlugin } from "@braintrust/templates-nunjucks-js";
+
+async function main() {
+  // Register nunjucks plugin before running tests
+  braintrust.registerTemplatePlugin(nunjucksPlugin);
+
+  const { failed } = await runTests({
+    name: "templates-nunjucks-basic-render",
+    braintrust,
+    tests: [testMustacheTemplate, testNunjucksTemplate],
+    skipCoverage: true,
+  });
+
+  if (failed.length > 0) {
+    process.exit(1);
+  }
+}
+
+main().catch((err) => {
+  console.error("Fatal error:", err);
+  process.exit(1);
+});
diff --git a/integrations/templates-nunjucks/src/index.test.ts b/integrations/templates-nunjucks/src/index.test.ts
new file mode 100644
index 000000000..60bee39c1
--- /dev/null
+++ b/integrations/templates-nunjucks/src/index.test.ts
@@ -0,0 +1,728 @@
+import { describe, test, expect, beforeAll } from "vitest";
+import { registerTemplatePlugin, Prompt } from "braintrust";
+import { nunjucksPlugin } from "./index";
+
+// Register and activate the plugin for all tests
+beforeAll(() => {
+  // registerTemplatePlugin will auto-activate using the plugin's
+  // `defaultOptions` when available.
+  registerTemplatePlugin(nunjucksPlugin);
+});
+
+describe("nunjucks rendering via Prompt", () => {
+  test("renders variable and control structures", () => {
+    const prompt = new Prompt(
+      {
+        name: "test-prompt",
+        slug: "test-prompt",
+        prompt_data: {
+          prompt: {
+            type: "chat",
+            messages: [
+              {
+                role: "user",
+                content:
+                  "Hello {{ name | upper }} {% if age > 18 %}Adult{% else %}Minor{% endif %}",
+              },
+            ],
+          },
+          options: { model: "gpt-4" },
+        },
+      },
+      {},
+      false,
+    );
+
+    const result = prompt.build(
+      { name: "alice", age: 30 },
+      { templateFormat: "nunjucks" },
+    );
+    expect(result.messages[0]?.content).toBe("Hello ALICE Adult");
+  });
+
+  test("loops render", () => {
+    const prompt = new Prompt(
+      {
+        name: "test-prompt",
+        slug: "test-prompt",
+        prompt_data: {
+          prompt: {
+            type: "chat",
+            messages: [
+              {
+                role: "user",
+                content: `{% for item in items %}{{ item }},{% endfor %}`,
+              },
+            ],
+          },
+          options: { model: "gpt-4" },
+        },
+      },
+      {},
+      false,
+    );
+
+    const result = prompt.build(
+      { items: ["a", "b"] },
+      { templateFormat: "nunjucks" },
+    );
+    expect(result.messages[0]?.content).toBe("a,b,");
+  });
+
+  test("strict mode throws for missing top-level variable", () => {
+    const prompt = new Prompt(
+      {
+        name: "test-prompt",
+        slug: "test-prompt",
+        prompt_data: {
+          prompt: {
+            type: "chat",
+            messages: [
+              {
+                role: "user",
+                content: "Hello {{ name }}",
+              },
+            ],
+          },
+          options: { model: "gpt-4" },
+        },
+      },
+      {},
+      false,
+    );
+
+    expect(() =>
+      prompt.build({ user: "x" }, { templateFormat: "nunjucks", strict: true }),
+    ).toThrow();
+  });
+
+  test("strict mode passes for defined variable and filters", () => {
+    const prompt = new Prompt(
+      {
+        name: "test-prompt",
+        slug: "test-prompt",
+        prompt_data: {
+          prompt: {
+            type: "chat",
+            messages: [
+              {
+                role: "user",
+                content: "Hello {{ name | upper }}",
+              },
+            ],
+          },
+          options: { model: "gpt-4" },
+        },
+      },
+      {},
+      false,
+    );
+
+    expect(() =>
+      prompt.build(
+        { name: "alice" },
+        { templateFormat: "nunjucks", strict: true },
+      ),
+    ).not.toThrow();
+  });
+
+  test("strict mode: for over undefined is empty (does not throw)", () => {
+    const prompt1 = new Prompt(
+      {
+        name: "test-prompt",
+        slug: "test-prompt",
+        prompt_data: {
+          prompt: {
+            type: "chat",
+            messages: [
+              {
+                role: "user",
+                content: `{% for item in items %}{{ item }}{% endfor %}`,
+              },
+            ],
+          },
+          options: { model: "gpt-4" },
+        },
+      },
+      {},
+      false,
+    );
+
+    expect(() =>
+      prompt1.build(
+        { items: [1, 2, 3] },
+        { templateFormat: "nunjucks", strict: true },
+      ),
+    ).not.toThrow();
+
+    expect(() =>
+      prompt1.build({}, { templateFormat: "nunjucks", strict: true }),
+    ).not.toThrow();
+  });
+
+  test("strict mode: nested path with numeric index using brackets", () => {
+    const prompt = new Prompt(
+      {
+        name: "test-prompt",
+        slug: "test-prompt",
+        prompt_data: {
+          prompt: {
+            type: "chat",
+            messages: [
+              {
+                role: "user",
+                content: `{{ user.addresses[2].city }}`,
+              },
+            ],
+          },
+          options: { model: "gpt-4" },
+        },
+      },
+      {},
+      false,
+    );
+
+    const ok = { user: { addresses: [{}, {}, { city: "SF" }] } };
+    expect(() =>
+      prompt.build(ok, { templateFormat: "nunjucks", strict: true }),
+    ).not.toThrow();
+
+    const bad = { user: {} };
+    expect(() =>
+      prompt.build(bad, { templateFormat: "nunjucks", strict: true }),
+    ).toThrow();
+  });
+
+  test("renders nested object properties", () => {
+    const prompt = new Prompt(
+      {
+        name: "test-prompt",
+        slug: "test-prompt",
+        prompt_data: {
+          prompt: {
+            type: "chat",
+            messages: [
+              {
+                role: "user",
+                content: "{{ user.profile.name }}",
+              },
+            ],
+          },
+          options: { model: "gpt-4" },
+        },
+      },
+      {},
+      false,
+    );
+
+    const result = prompt.build(
+      { user: { profile: { name: "Alice" } } },
+      { templateFormat: "nunjucks" },
+    );
+    expect(result.messages[0]?.content).toBe("Alice");
+  });
+
+  test("renders multiple variables with context", () => {
+    const prompt = new Prompt(
+      {
+        name: "test-prompt",
+        slug: "test-prompt",
+        prompt_data: {
+          prompt: {
+            type: "chat",
+            messages: [
+              {
+                role: "user",
+                content:
+                  "{{ firstName }} {{ lastName }} is {{ age }} years old",
+              },
+            ],
+          },
+          options: { model: "gpt-4" },
+        },
+      },
+      {},
+      false,
+    );
+
+    const result = prompt.build(
+      { firstName: "Bob", lastName: "Smith", age: 25 },
+      { templateFormat: "nunjucks" },
+    );
+    expect(result.messages[0]?.content).toBe("Bob Smith is 25 years old");
+  });
+
+  test("renders with string concatenation", () => {
+    const prompt = new Prompt(
+      {
+        name: "test-prompt",
+        slug: "test-prompt",
+        prompt_data: {
+          prompt: {
+            type: "chat",
+            messages: [
+              {
+                role: "user",
+                content: "{{ greeting ~ ' ' ~ name }}",
+              },
+            ],
+          },
+          options: { model: "gpt-4" },
+        },
+      },
+      {},
+      false,
+    );
+
+    const result = prompt.build(
+      { greeting: "Hello", name: "World" },
+      { templateFormat: "nunjucks" },
+    );
+    expect(result.messages[0]?.content).toBe("Hello World");
+  });
+
+  test("renders numeric operations", () => {
+    const prompt = new Prompt(
+      {
+        name: "test-prompt",
+        slug: "test-prompt",
+        prompt_data: {
+          prompt: {
+            type: "chat",
+            messages: [
+              {
+                role: "user",
+                content: "Total: {{ price * quantity }}",
+              },
+            ],
+          },
+          options: { model: "gpt-4" },
+        },
+      },
+      {},
+      false,
+    );
+
+    const result = prompt.build(
+      { price: 10, quantity: 3 },
+      { templateFormat: "nunjucks" },
+    );
+    expect(result.messages[0]?.content).toBe("Total: 30");
+  });
+
+  test("renders with filters and context", () => {
+    const prompt = new Prompt(
+      {
+        name: "test-prompt",
+        slug: "test-prompt",
+        prompt_data: {
+          prompt: {
+            type: "chat",
+            messages: [
+              {
+                role: "user",
+                content: "{{ message | upper | trim }}",
+              },
+            ],
+          },
+          options: { model: "gpt-4" },
+        },
+      },
+      {},
+      false,
+    );
+
+    const result = prompt.build(
+      { message: "  hello world  " },
+      { templateFormat: "nunjucks" },
+    );
+    expect(result.messages[0]?.content).toBe("HELLO WORLD");
+  });
+
+  test("renders array elements with index", () => {
+    const prompt = new Prompt(
+      {
+        name: "test-prompt",
+        slug: "test-prompt",
+        prompt_data: {
+          prompt: {
+            type: "chat",
+            messages: [
+              {
+                role: "user",
+                content: "First: {{ items[0] }}, Last: {{ items[2] }}",
+              },
+            ],
+          },
+          options: { model: "gpt-4" },
+        },
+      },
+      {},
+      false,
+    );
+
+    const result = prompt.build(
+      { items: ["apple", "banana", "cherry"] },
+      { templateFormat: "nunjucks" },
+    );
+    expect(result.messages[0]?.content).toBe("First: apple, Last: cherry");
+  });
+
+  test("renders nested arrays and objects", () => {
+    const prompt = new Prompt(
+      {
+        name: "test-prompt",
+        slug: "test-prompt",
+        prompt_data: {
+          prompt: {
+            type: "chat",
+            messages: [
+              {
+                role: "user",
+                content: "{{ users[0].name }} from {{ users[0].city }}",
+              },
+            ],
+          },
+          options: { model: "gpt-4" },
+        },
+      },
+      {},
+      false,
+    );
+
+    const result = prompt.build(
+      {
+        users: [
+          { name: "John", city: "NYC" },
+          { name: "Jane", city: "LA" },
+        ],
+      },
+      { templateFormat: "nunjucks" },
+    );
+    expect(result.messages[0]?.content).toBe("John from NYC");
+  });
+
+  test("renders with default filter", () => {
+    const prompt = new Prompt(
+      {
+        name: "test-prompt",
+        slug: "test-prompt",
+        prompt_data: {
+          prompt: {
+            type: "chat",
+            messages: [
+              {
+                role: "user",
+                content: "{{ name | default('Guest') }}",
+              },
+            ],
+          },
+          options: { model: "gpt-4" },
+        },
+      },
+      {},
+      false,
+    );
+
+    const result1 = prompt.build(
+      { name: "Alice" },
+      { templateFormat: "nunjucks" },
+    );
+    expect(result1.messages[0]?.content).toBe("Alice");
+
+    const result2 = prompt.build({}, { templateFormat: "nunjucks" });
+    expect(result2.messages[0]?.content).toBe("Guest");
+  });
+
+  test("renders ternary expressions", () => {
+    const prompt = new Prompt(
+      {
+        name: "test-prompt",
+        slug: "test-prompt",
+        prompt_data: {
+          prompt: {
+            type: "chat",
+            messages: [
+              {
+                role: "user",
+                content: "{{ user.name if user else 'Anonymous' }}",
+              },
+            ],
+          },
+          options: { model: "gpt-4" },
+        },
+      },
+      {},
+      false,
+    );
+
+    const result1 = prompt.build(
+      { user: { name: "Alice" } },
+      { templateFormat: "nunjucks" },
+    );
+    expect(result1.messages[0]?.content).toBe("Alice");
+
+    const result2 = prompt.build({}, { templateFormat: "nunjucks" });
+    expect(result2.messages[0]?.content).toBe("Anonymous");
+  });
+
+  test("renders with multiple filters chained", () => {
+    const prompt = new Prompt(
+      {
+        name: "test-prompt",
+        slug: "test-prompt",
+        prompt_data: {
+          prompt: {
+            type: "chat",
+            messages: [
+              {
+                role: "user",
+                content: "{{ text | lower | trim }}",
+              },
+            ],
+          },
+          options: { model: "gpt-4" },
+        },
+      },
+      {},
+      false,
+    );
+
+    const result = prompt.build(
+      { text: "  HELLO WORLD  " },
+      { templateFormat: "nunjucks" },
+    );
+    expect(result.messages[0]?.content).toBe("hello world");
+  });
+
+  test("renders complex nested context", () => {
+    const prompt = new Prompt(
+      {
+        name: "test-prompt",
+        slug: "test-prompt",
+        prompt_data: {
+          prompt: {
+            type: "chat",
+            messages: [
+              {
+                role: "user",
+                content:
+                  "{{ order.customer.name }} ordered {{ order.items[0].name }} for ${{ order.total }}",
+              },
+            ],
+          },
+          options: { model: "gpt-4" },
+        },
+      },
+      {},
+      false,
+    );
+
+    const result = prompt.build(
+      {
+        order: {
+          customer: { name: "Alice" },
+          items: [{ name: "Widget", price: 10 }],
+          total: 10,
+        },
+      },
+      { templateFormat: "nunjucks" },
+    );
+    expect(result.messages[0]?.content).toBe("Alice ordered Widget for $10");
+  });
+
+  test("renders with length filter on arrays", () => {
+    const prompt = new Prompt(
+      {
+        name: "test-prompt",
+        slug: "test-prompt",
+        prompt_data: {
+          prompt: {
+            type: "chat",
+            messages: [
+              {
+                role: "user",
+                content: "You have {{ items | length }} items",
+              },
+            ],
+          },
+          options: { model: "gpt-4" },
+        },
+      },
+      {},
+      false,
+    );
+
+    const result = prompt.build(
+      { items: ["a", "b", "c", "d"] },
+      { templateFormat: "nunjucks" },
+    );
+    expect(result.messages[0]?.content).toBe("You have 4 items");
+  });
+
+  test("renders with join filter", () => {
+    const prompt = new Prompt(
+      {
+        name: "test-prompt",
+        slug: "test-prompt",
+        prompt_data: {
+          prompt: {
+            type: "chat",
+            messages: [
+              {
+                role: "user",
+                content: "{{ tags | join(', ') }}",
+              },
+            ],
+          },
+          options: { model: "gpt-4" },
+        },
+      },
+      {},
+      false,
+    );
+
+    const result = prompt.build(
+      { tags: ["red", "green", "blue"] },
+      { templateFormat: "nunjucks" },
+    );
+    expect(result.messages[0]?.content).toBe("red, green, blue");
+  });
+});
+
+describe("nunjucks linting", () => {
+  test("lint throws for missing variable", () => {
+    const prompt = new Prompt(
+      {
+        name: "test-prompt",
+        slug: "test-prompt",
+        prompt_data: {
+          prompt: {
+            type: "chat",
+            messages: [
+              {
+                role: "user",
+                content: "Hello {{ user.name }}",
+              },
+            ],
+          },
+          options: { model: "gpt-4" },
+        },
+      },
+      {},
+      false,
+    );
+
+    expect(() =>
+      prompt.build({}, { templateFormat: "nunjucks", strict: true }),
+    ).toThrow();
+  });
+
+  test("lint passes for valid template with loops", () => {
+    const prompt = new Prompt(
+      {
+        name: "test-prompt",
+        slug: "test-prompt",
+        prompt_data: {
+          prompt: {
+            type: "chat",
+            messages: [
+              {
+                role: "user",
+                content: `{% for item in items %}{{ item }}{% endfor %}`,
+              },
+            ],
+          },
+          options: { model: "gpt-4" },
+        },
+      },
+      {},
+      false,
+    );
+
+    expect(() =>
+      prompt.build({}, { templateFormat: "nunjucks", strict: true }),
+    ).not.toThrow();
+  });
+
+  test("lint passes for valid template with conditionals", () => {
+    const prompt = new Prompt(
+      {
+        name: "test-prompt",
+        slug: "test-prompt",
+        prompt_data: {
+          prompt: {
+            type: "chat",
+            messages: [
+              {
+                role: "user",
+                content: `{% if user %}{{ user.name }}{% endif %}`,
+              },
+            ],
+          },
+          options: { model: "gpt-4" },
+        },
+      },
+      {},
+      false,
+    );
+
+    expect(() =>
+      prompt.build({}, { templateFormat: "nunjucks", strict: true }),
+    ).not.toThrow();
+  });
+
+  test("lint throws for invalid template syntax", () => {
+    const prompt = new Prompt(
+      {
+        name: "test-prompt",
+        slug: "test-prompt",
+        prompt_data: {
+          prompt: {
+            type: "chat",
+            messages: [
+              {
+                role: "user",
+                content: "{{ unclosed",
+              },
+            ],
+          },
+          options: { model: "gpt-4" },
+        },
+      },
+      {},
+      false,
+    );
+
+    expect(() =>
+      prompt.build({}, { templateFormat: "nunjucks", strict: true }),
+    ).toThrow();
+  });
+
+  test("lint throws for mismatched tags", () => {
+    const prompt = new Prompt(
+      {
+        name: "test-prompt",
+        slug: "test-prompt",
+        prompt_data: {
+          prompt: {
+            type: "chat",
+            messages: [
+              {
+                role: "user",
+                content: "{% if x %}{% endfor %}",
+              },
+            ],
+          },
+          options: { model: "gpt-4" },
+        },
+      },
+      {},
+      false,
+    );
+
+    expect(() =>
+      prompt.build({}, { templateFormat: "nunjucks", strict: true }),
+    ).toThrow();
+  });
+});
diff --git a/integrations/templates-nunjucks/src/index.ts b/integrations/templates-nunjucks/src/index.ts
new file mode 100644
index 000000000..e88e1cb1e
--- /dev/null
+++ b/integrations/templates-nunjucks/src/index.ts
@@ -0,0 +1,142 @@
+import * as nunjucks from "nunjucks";
+
+import type { TemplateRendererPlugin } from "braintrust";
+
+/**
+ * Configuration options for the Nunjucks template renderer.
+ *
+ * @example
+ * ```typescript
+ * import { registerTemplatePlugin } from "braintrust";
+ * import { nunjucksPlugin, type NunjucksOptions } from "@braintrust/templates-nunjucks-js";
+ *
+ * // Configure options before registering
+ * nunjucksPlugin.defaultOptions = {
+ *   autoescape: true,
+ *   throwOnUndefined: false
+ * } as NunjucksOptions;
+ *
+ * registerTemplatePlugin(nunjucksPlugin);
+ * ```
+ */
+export interface NunjucksOptions {
+  /**
+   * Controls whether HTML escaping is enabled for template variables.
+   *
+   * When `true` (default), variables are automatically HTML-escaped to prevent XSS attacks.
+   * When `false`, variables are rendered as-is without escaping.
+   *
+   * @default true
+   * @example
+   * ```typescript
+   * // With autoescape enabled (default)
+   * nunjucksPlugin.defaultOptions = { autoescape: true };
+   * // Template: "{{ html }}"
+   * // Variables: { html: "<div>Test</div>" }
+   * // Output: "&lt;div&gt;Test&lt;/div&gt;"
+   *
+   * // With autoescape disabled
+   * nunjucksPlugin.defaultOptions = { autoescape: false };
+   * // Output: "<div>Test</div>"
+   * ```
+   */
+  autoescape?: boolean;
+
+  /**
+   * Controls whether undefined variables throw errors.
+   *
+   * When `true`, accessing undefined variables throws an error, making it easier to catch typos.
+   * When `false` (default), undefined variables render as empty strings.
+   *
+   * Note: When using `prompt.build()` with `strict: true`, this is always enabled for linting.
+   *
+   * @default false
+   * @example
+   * ```typescript
+   * // Lenient mode (default) - typos render as empty
+   * nunjucksPlugin.defaultOptions = { throwOnUndefined: false };
+   * // Template: "Hello {{ userName }}"
+   * // Variables: { userName: "Alice" }
+   * // Output: "Hello Alice"
+   *
+   * // Strict mode - typos throw errors
+   * nunjucksPlugin.defaultOptions = { throwOnUndefined: true };
+   * // Output: Error: Variable 'userName' is undefined
+   * ```
+   */
+  throwOnUndefined?: boolean;
+}
+
+/**
+ * Nunjucks template renderer plugin for Braintrust.
+ *
+ * Provides support for Nunjucks/Jinja2-style templating in Braintrust prompts,
+ * including loops, conditionals, filters, and more.
+ *
+ * @example
+ * ```typescript
+ * import { registerTemplatePlugin, Prompt } from "braintrust";
+ * import { nunjucksPlugin } from "@braintrust/templates-nunjucks-js";
+ *
+ * // Register the plugin
+ * registerTemplatePlugin(nunjucksPlugin);
+ *
+ * // Use in prompts
+ * const prompt = new Prompt({
+ *   name: "example",
+ *   slug: "example",
+ *   prompt_data: {
+ *     prompt: {
+ *       type: "chat",
+ *       messages: [{
+ *         role: "user",
+ *         content: "{% for item in items %}{{ item }}{% if not loop.last %}, {% endif %}{% endfor %}"
+ *       }]
+ *     },
+ *     options: { model: "gpt-4" }
+ *   }
+ * }, {}, false);
+ *
+ * const result = prompt.build(
+ *   { items: ["apple", "banana", "cherry"] },
+ *   { templateFormat: "nunjucks" }
+ * );
+ * // Output: "apple, banana, cherry"
+ * ```
+ */
+export const nunjucksPlugin: TemplateRendererPlugin = {
+  name: "nunjucks",
+  defaultOptions: {
+    autoescape: true,
+    throwOnUndefined: false,
+  } as NunjucksOptions,
+  createRenderer() {
+    const opts = (this.defaultOptions ?? {}) as NunjucksOptions;
+    const autoescape = opts.autoescape ?? true;
+    const throwOnUndefined = opts.throwOnUndefined ?? false;
+
+    const env = new nunjucks.Environment(null, {
+      autoescape,
+      throwOnUndefined,
+    });
+
+    const strictEnv = new nunjucks.Environment(null, {
+      autoescape: true,
+      throwOnUndefined: true,
+    });
+
+    return {
+      render(
+        template: string,
+        variables: Record<string, unknown>,
+        _escape: (v: unknown) => string,
+        strict: boolean,
+      ) {
+        return (strict ? strictEnv : env).renderString(template, variables);
+      },
+      lint(template: string, variables: Record<string, unknown>) {
+        strictEnv.renderString(template, variables);
+      },
+    };
+  },
+};
diff --git a/integrations/templates-nunjucks/tsconfig.json b/integrations/templates-nunjucks/tsconfig.json
new file mode 100644
index 000000000..47119abe2
--- /dev/null
+++ b/integrations/templates-nunjucks/tsconfig.json
@@ -0,0 +1,13 @@
+{
+  "compilerOptions": {
+    "declaration": true,
+    "lib": ["es2022"],
+    "module": "esnext",
+    "target": "es2022",
+    "moduleResolution": "node",
+    "strict": true,
+    "esModuleInterop": true,
+    "skipLibCheck": true
+  },
+  "include": ["src"]
+}
diff --git a/integrations/templates-nunjucks/tsup.config.ts b/integrations/templates-nunjucks/tsup.config.ts
new file mode 100644
index 000000000..41099bc7a
--- /dev/null
+++ b/integrations/templates-nunjucks/tsup.config.ts
@@ -0,0 +1,10 @@
+import { defineConfig } from "tsup";
+
+export default defineConfig({
+  entry: ["src/index.ts"],
+  format: ["cjs", "esm"],
+  outDir: "dist",
+  dts: true,
+  splitting: true,
+  clean: true,
+});
diff --git a/integrations/templates-nunjucks/vitest.config.ts b/integrations/templates-nunjucks/vitest.config.ts
new file mode 100644
index 000000000..73a26a648
--- /dev/null
+++ b/integrations/templates-nunjucks/vitest.config.ts
@@ -0,0 +1,7 @@
+import { defineConfig } from "vitest/config";
+
+export default defineConfig({
+  test: {
+    include: ["tests/**/*.test.ts", "src/**/*.test.ts"],
+  },
+});
diff --git a/integrations/temporal-js/vitest.config.ts b/integrations/temporal-js/vitest.config.ts
index 77a73cf2e..73a26a648 100644
--- a/integrations/temporal-js/vitest.config.ts
+++ b/integrations/temporal-js/vitest.config.ts
@@ -1,5 +1,7 @@
 import { defineConfig } from "vitest/config";
 
 export default defineConfig({
-  test: {},
+  test: {
+    include: ["tests/**/*.test.ts", "src/**/*.test.ts"],
+  },
 });
diff --git a/integrations/vercel-ai-sdk/vitest.config.ts b/integrations/vercel-ai-sdk/vitest.config.ts
index e69de29bb..73a26a648 100644
--- a/integrations/vercel-ai-sdk/vitest.config.ts
+++ b/integrations/vercel-ai-sdk/vitest.config.ts
@@ -0,0 +1,7 @@
+import { defineConfig } from "vitest/config";
+
+export default defineConfig({
+  test: {
+    include: ["tests/**/*.test.ts", "src/**/*.test.ts"],
+  },
+});
diff --git a/js/Makefile b/js/Makefile
index 125beef2b..42ee5a23e 100644
--- a/js/Makefile
+++ b/js/Makefile
@@ -163,23 +163,10 @@ clean:
 
 SMOKE_DIR := smoke
 
-# Run smoke tests (always prepares - relies on turbo/tsup caching for build efficiency)
+# Run smoke tests - delegates to smoke/Makefile which handles auto-discovery and tarball creation
 # Usage: make test-smoke [TEST_NAME...]
 test-smoke:
-	@TESTS="$(filter-out test-smoke,$(MAKECMDGOALS))"; \
-	SMOKE_ABS="$$(pwd)/$(SMOKE_DIR)"; \
-	cd $(SMOKE_DIR) && ./prepare-tests.sh $$TESTS; \
-	EXIT_CODE=0; \
-	cd $$SMOKE_ABS && ./run-tests.sh $$TESTS || EXIT_CODE=$$?; \
-	echo ""; \
-	echo "Restoring package files..."; \
-	cd $$SMOKE_ABS && \
-	for dir in tests/*/; do \
-		if [ -f "$$dir/package.json" ] && grep -q '"restore"' "$$dir/package.json" 2>/dev/null; then \
-			(cd "$$dir" && npm run restore >/dev/null 2>&1 && echo "  ✓ Restored $$(basename $$dir)") || true; \
-		fi; \
-	done; \
-	exit $$EXIT_CODE
+	@cd $(SMOKE_DIR) && $(MAKE) test $(filter-out test-smoke,$(MAKECMDGOALS))
 
 # Allow passing test names as make targets (they become no-ops)
 cloudflare-worker deno nextjs-instrumentation otel-v1 span span-jest:
diff --git a/js/README.md b/js/README.md
index 1b09f9b4b..e09fc1f9e 100644
--- a/js/README.md
+++ b/js/README.md
@@ -42,3 +42,22 @@ async function main() {
 
 main().catch(console.error);
 ```
+
+### Browser Support
+
+**For browser-only applications, use the dedicated browser package:**
+
+```bash
+npm install @braintrust/browser
+```
+
+The `@braintrust/browser` package is optimized for browser environments and includes the `als-browser` polyfill for AsyncLocalStorage support. It's a standalone package with no peer dependencies.
+
+**When to use each package:**
+
+- **`braintrust`** (this package) - For Node.js applications, full-stack frameworks (Next.js, etc.), and edge runtimes with native AsyncLocalStorage (Cloudflare Workers, Vercel Edge)
+- **`@braintrust/browser`** - For browser-only applications that need AsyncLocalStorage support in standard browsers
+
+See the [@braintrust/browser README](../integrations/browser-js/README.md) for more details.
+
+**Breaking change in v3.0.0:** The `braintrust/browser` subpath export has been deprecated. Browser users should migrate to the `@braintrust/browser` package.
diff --git a/js/deno.json b/js/deno.json
new file mode 100644
index 000000000..353175f94
--- /dev/null
+++ b/js/deno.json
@@ -0,0 +1,6 @@
+{
+  "name": "braintrust",
+  "exports": {
+    ".": "./dist/index.mjs"
+  }
+}
diff --git a/js/package.json b/js/package.json
index b211d7cfb..b9d5c9f9a 100644
--- a/js/package.json
+++ b/js/package.json
@@ -1,7 +1,7 @@
 {
   "name": "braintrust",
-  "version": "2.1.0",
-  "description": "SDK for integrating Braintrust",
+  "version": "3.0.0",
+  "description": "SDK for integrating Braintrust.",
   "repository": {
     "type": "git",
     "url": "git+https://github.com/braintrustdata/braintrust-sdk.git",
@@ -33,12 +33,12 @@
       "browser": "./dist/browser.mjs",
       "import": "./dist/index.mjs",
       "require": "./dist/index.js",
-      "default": "./dist/browser.mjs"
+      "default": "./dist/index.mjs"
     },
     "./browser": {
       "import": "./dist/browser.mjs",
-      "module": "./dist/browser.mjs",
-      "require": "./dist/browser.js"
+      "require": "./dist/browser.js",
+      "default": "./dist/browser.mjs"
     },
     "./node": {
       "types": "./dist/index.d.ts",
@@ -132,7 +132,6 @@
   "dependencies": {
     "@ai-sdk/provider": "^1.1.3",
     "@next/env": "^14.2.3",
-    "@types/nunjucks": "^3.2.6",
     "@vercel/functions": "^1.0.2",
     "argparse": "^2.0.1",
     "boxen": "^8.0.1",
@@ -148,7 +147,6 @@
     "http-errors": "^2.0.0",
     "minimatch": "^9.0.3",
     "mustache": "^4.2.0",
-    "nunjucks": "^3.2.4",
     "pluralize": "^8.0.0",
     "simple-git": "^3.21.0",
     "source-map": "^0.7.4",
diff --git a/js/smoke/Makefile b/js/smoke/Makefile
index effaa15e5..bcd11e472 100644
--- a/js/smoke/Makefile
+++ b/js/smoke/Makefile
@@ -1,36 +1,52 @@
-# Auto-discover scenarios (any folder in scenarios/ with a Makefile)
-SCENARIOS := $(shell find scenarios -mindepth 1 -maxdepth 1 -type d -exec test -f {}/Makefile \; -print | sed 's|scenarios/||' | sort)
+## Discover integration scenarios under ../../integrations
+SCRIPTDIR := ../../integrations
+LOCAL_MAKEFILES := $(shell find scenarios -type f -path 'scenarios/*/Makefile' -not -path '*/node_modules/*' 2>/dev/null)
+INTEGRATION_MAKEFILES := $(shell find $(SCRIPTDIR) -type f -path '*/smoke/scenarios/*/Makefile' -not -path '*/node_modules/*' 2>/dev/null)
+SCENARIO_MAKEFILES := $(LOCAL_MAKEFILES) $(INTEGRATION_MAKEFILES)
+LOCAL_SCENARIOS := $(patsubst scenarios/%/Makefile,%,$(LOCAL_MAKEFILES))
+INTEGRATION_SCENARIOS := $(shell echo "$(INTEGRATION_MAKEFILES)" | tr ' ' '\n' | sed 's|$(SCRIPTDIR)/||' | sed 's|/smoke/scenarios/|/|' | sed 's|/Makefile$$||' | tr '\n' ' ')
+SCENARIOS := $(LOCAL_SCENARIOS) $(INTEGRATION_SCENARIOS)
 
-.PHONY: help setup test list clean
+.PHONY: help setup test list clean discover
 
-# =============================================================================
-# Help
-# =============================================================================
+# Declare all scenarios as phony targets with empty recipes
+# This prevents "No rule to make target" errors when running: make test scenario-name
+.PHONY: $(LOCAL_SCENARIOS) $(INTEGRATION_SCENARIOS)
+$(LOCAL_SCENARIOS) $(INTEGRATION_SCENARIOS):
+	@: # Empty recipe - actual test logic is in the test target
+
+## ============================================================================
+## Help
+## ============================================================================
 
 help:
 	@echo "Smoke Test Infrastructure"
 	@echo ""
 	@echo "Available targets:"
-	@echo "  make test            - Run all scenarios (builds SDK once if needed)"
-	@echo "  make test <scenario> - Run specific scenario (e.g., make test otel-v1)"
-	@echo "  make setup           - Ensure SDK artifacts + shared package are ready"
-	@echo "  make clean           - Remove all build artifacts (force rebuild)"
-	@echo "  make list            - List discovered scenarios"
+	@echo "  make test                - Run all discovered integration scenarios"
+	@echo "  make test <integration/name> - Run specific scenario (e.g., make test templates-nunjucks/basic-render)"
+	@echo "  make setup               - Ensure SDK artifacts + shared package are ready"
+	@echo "  make clean               - Remove all build artifacts (force rebuild)"
+	@echo "  make list                - List discovered scenarios"
 	@echo ""
 	@echo "Environment variables:"
 	@echo "  BRAINTRUST_TAR           - Path to braintrust tarball (auto-set by parent when running locally)"
+	@echo "  BRAINTRUST_BROWSER_TAR   - Path to browser tarball (auto-set by parent when running locally)"
 	@echo "  BRAINTRUST_OTEL_TAR      - Path to otel tarball (auto-set by parent when running locally)"
 	@echo "  SMOKE_V2_SHARED_DIST     - Path to shared package dist (auto-set by parent when running locally)"
 	@echo ""
-	@echo "Running individual scenarios:"
-	@echo "  cd scenarios/otel-v1 && make test   - Runs standalone, builds if needed"
-	@echo ""
-	@echo "Discovered scenarios:"
-	@for scenario in $(SCENARIOS); do echo "  - $$scenario"; done
+	@echo "Discovered local scenarios:"; \
+	for s in $(LOCAL_SCENARIOS); do \
+		if [ -n "$$s" ]; then echo "  - $$s"; fi; \
+	done; \
+	echo "Discovered integration scenarios:"; \
+	for s in $(INTEGRATION_SCENARIOS); do \
+		if [ -n "$$s" ]; then echo "  - $$s"; fi; \
+	done
 
-# =============================================================================
-# Setup - Build SDK + shared package
-# =============================================================================
+## ============================================================================
+## Setup - Build SDK + shared package
+## ============================================================================
 
 setup:
 	@echo "==> Setting up smoke"
@@ -42,16 +58,28 @@ setup:
 	else \
 		echo "==> Building SDK and creating tarball"; \
 		cd ../../.. && pnpm exec turbo build --filter=braintrust && pnpm --filter=braintrust pack --pack-destination sdk/js/artifacts; \
-		\
 		for f in sdk/js/artifacts/braintrust-*.tgz; do \
-			if [ "$$(basename $$f)" != "braintrust-latest.tgz" ] && \
-			   [ "$$(basename $$f)" != "braintrust-otel-latest.tgz" ]; then \
+			if [ "$$(basename $$f)" != "braintrust-latest.tgz" ] && [ "$$(basename $$f)" != "braintrust-otel-latest.tgz" ] && [ "$$(basename $$f)" != "braintrust-browser-latest.tgz" ]; then \
 				cp "$$f" sdk/js/artifacts/braintrust-latest.tgz; \
 				break; \
 			fi; \
 		done; \
 	fi
 
+	@# Build browser package and create tarball if not provided
+	@if [ -n "$(BRAINTRUST_BROWSER_TAR)" ] && [ -f "$(BRAINTRUST_BROWSER_TAR)" ]; then \
+		echo "==> Using provided BRAINTRUST_BROWSER_TAR: $(BRAINTRUST_BROWSER_TAR)"; \
+	else \
+		echo "==> Building browser package and creating tarball"; \
+		cd ../../.. && pnpm exec turbo build --filter=@braintrust/browser && pnpm --filter=@braintrust/browser pack --pack-destination sdk/js/artifacts; \
+		for f in sdk/js/artifacts/braintrust-browser-*.tgz; do \
+			if [ "$$(basename $$f)" != "braintrust-browser-latest.tgz" ]; then \
+				cp "$$f" sdk/js/artifacts/braintrust-browser-latest.tgz; \
+				break; \
+			fi; \
+		done; \
+	fi
+
 	@# Build shared package if not provided
 	@if [ -n "$(SMOKE_V2_SHARED_DIST)" ] && [ -d "$(SMOKE_V2_SHARED_DIST)" ]; then \
 		echo "==> Using provided SMOKE_V2_SHARED_DIST: $(SMOKE_V2_SHARED_DIST)"; \
@@ -64,52 +92,72 @@ setup:
 		fi; \
 	fi
 
-# =============================================================================
-# Clean - Remove all build artifacts
-# =============================================================================
+## ============================================================================
+## Clean - Remove all build artifacts
+## ============================================================================
 
 clean:
 	@echo "==> Cleaning smoke artifacts"
 	rm -rf ../artifacts/*.tgz
 	rm -rf shared/dist shared/node_modules
 
-# =============================================================================
-# Test - Run scenarios
-# =============================================================================
+## ============================================================================
+## Test - Run scenarios
+## ============================================================================
+
+# Support positional scenario argument: make test integration/name
+
 
 test:
-	@REQUESTED="$(filter-out test,$(MAKECMDGOALS))"; \
-	\
+	@# Collect requested scenario names (strip any trailing /Makefile if provided by user)
+	@REQUESTED_RAW="$(filter-out test,$(MAKECMDGOALS))"; \
+	REQUESTED="$$(echo $$REQUESTED_RAW | tr ' ' '\n' | sed 's|/Makefile$$||' | tr '\n' ' ' | xargs)"; \
 	if [ -z "$$REQUESTED" ]; then \
 		SCENARIOS_TO_RUN="$(SCENARIOS)"; \
-		echo "==> Running all scenarios"; \
+		echo "==> Running all discovered scenarios"; \
 	else \
 		SCENARIOS_TO_RUN=""; \
 		for scenario in $$REQUESTED; do \
-			if [ ! -d "scenarios/$$scenario" ]; then \
-				echo "Error: Scenario '$$scenario' not found"; \
+			if echo "$$scenario" | grep -q '/'; then \
+				integration=$$(echo $$scenario | cut -d/ -f1); \
+				name=$$(echo $$scenario | cut -d/ -f2-); \
+				dir="$(SCRIPTDIR)/$$integration/smoke/scenarios/$$name"; \
+			else \
+				dir="scenarios/$$scenario"; \
+			fi; \
+			if [ ! -d "$$dir" ]; then \
+				echo "Error: Scenario '$$scenario' not found at $$dir"; \
 				echo "Available scenarios:"; \
-				for s in $(SCENARIOS); do echo "  - $$s"; done; \
+				for s in $(LOCAL_SCENARIOS) $(INTEGRATION_SCENARIOS); do \
+					echo "  - $$s"; \
+				done; \
 				exit 1; \
 			fi; \
-			SCENARIOS_TO_RUN="$$SCENARIOS_TO_RUN $$scenario"; \
+			SCENARIOS_TO_RUN="$$SCENARIOS_TO_RUN $$dir"; \
 		done; \
-		echo "==> Running scenarios:$$SCENARIOS_TO_RUN"; \
+		echo "==> Running scenarios: $$REQUESTED"; \
 	fi; \
 	\
 	$(MAKE) setup; \
 	\
 	: $${BRAINTRUST_TAR:=../artifacts/braintrust-latest.tgz}; \
+	: $${BRAINTRUST_BROWSER_TAR:=../artifacts/braintrust-browser-latest.tgz}; \
 	: $${BRAINTRUST_OTEL_TAR:=../artifacts/braintrust-otel-latest.tgz}; \
 	: $${SMOKE_V2_SHARED_DIST:=shared/dist}; \
-	export BRAINTRUST_TAR BRAINTRUST_OTEL_TAR SMOKE_V2_SHARED_DIST; \
+	export BRAINTRUST_TAR BRAINTRUST_BROWSER_TAR BRAINTRUST_OTEL_TAR SMOKE_V2_SHARED_DIST; \
 	\
 	FAILED_SCENARIOS=""; \
 	for scenario in $$SCENARIOS_TO_RUN; do \
 		echo ""; \
 		echo "=== Testing $$scenario ==="; \
-		if ! $(MAKE) -C scenarios/$$scenario test; then \
-			FAILED_SCENARIOS="$$FAILED_SCENARIOS $$scenario"; \
+		if [ -f "$$scenario/Makefile" ]; then \
+			if ! $(MAKE) -C $$scenario test; then \
+				FAILED_SCENARIOS="$$FAILED_SCENARIOS $$(echo $$scenario | sed 's|$(SCRIPTDIR)/||' | sed 's|/scenarios/|/|')"; \
+			fi; \
+		elif [ -f "$$scenario/test.js" ]; then \
+			( cd $$scenario && node test.js ) || FAILED_SCENARIOS="$$FAILED_SCENARIOS $$(echo $$scenario | sed 's|$(SCRIPTDIR)/||' | sed 's|/scenarios/|/|')"; \
+		else \
+			FAILED_SCENARIOS="$$FAILED_SCENARIOS $$(echo $$scenario | sed 's|$(SCRIPTDIR)/||' | sed 's|/scenarios/|/|')"; \
 		fi; \
 	done; \
 	\
@@ -121,17 +169,11 @@ test:
 		echo "✓ All requested scenarios passed"; \
 	fi
 
-# =============================================================================
-# List - Show discovered scenarios
-# =============================================================================
+## ============================================================================
+## List - Show discovered scenarios
+## ============================================================================
 
 list:
-	@echo "Discovered scenarios:"
-	@for scenario in $(SCENARIOS); do echo "  - $$scenario"; done
-
-# =============================================================================
-# Make scenario names valid targets (no-ops to support "make test otel-v1")
-# =============================================================================
-
-$(SCENARIOS):
-	@:
+	@echo "Discovered scenarios:"; \
+	for s in $(SCENARIOS); do echo "  - $$s"; done
+	@echo ''
diff --git a/js/smoke/README.md b/js/smoke/README.md
index f0b52cec5..89b725452 100644
--- a/js/smoke/README.md
+++ b/js/smoke/README.md
@@ -5,9 +5,18 @@ Smoke test infrastructure verifying SDK installation across different runtimes a
 ## Quick Reference
 
 ```bash
-make test              # Run all scenarios (doesn't exit early on failures)
-make test otel-v1      # Run specific scenario
-make list              # List available scenarios
+# From sdk/js/:
+make test-smoke                    # Run all scenarios
+
+# From sdk/js/smoke/:
+make test                          # Run all scenarios (local + integration)
+make test deno-node                # Run specific local scenario
+make test templates-nunjucks/jest  # Run integration scenario
+make list                          # List all discovered scenarios
+
+# From a specific scenario:
+cd scenarios/deno-node
+make test                          # Auto-creates tarball if needed
 ```
 
 ## Output Standardization (REQUIRED)
@@ -182,6 +191,72 @@ test: setup
 
 This ensures all tests run and display their results, but the suite still fails if any test failed.
 
+## Environment Variables & Tarball Creation
+
+### Automatic Tarball Creation
+
+Scenarios automatically create tarballs if they're not provided via environment variables. This happens during the `setup` target:
+
+1. **Check for existing tarball**: If `BRAINTRUST_TAR` env var is set and points to a valid file, use it
+2. **Build from source**: Otherwise, build SDK and create tarball:
+
+   ```bash
+   cd ../../.. && pnpm exec turbo build --filter=braintrust && \
+   mkdir-p artifacts && pnpm pack --pack-destination artifacts
+   ```
+
+3. **Rename to well-known path**: Copy to `braintrust-latest.tgz` for consistent references
+
+### Environment Variables
+
+- **`BRAINTRUST_TAR`**: Path to braintrust tarball (auto-created if not set)
+
+  - Example: `../artifacts/braintrust-latest.tgz`
+
+- **`BRAINTRUST_OTEL_TAR`**: Path to @braintrust/otel tarball (auto-created for scenarios that need it)
+
+  - Example: `../artifacts/braintrust-otel-latest.tgz`
+
+- **`BRAINTRUST_TEMPLATES_NUNJUCKS_JS_TAR`**: Path to @braintrust/templates-nunjucks-js tarball
+
+  - Example: `../artifacts/braintrust-templates-nunjucks-js-latest.tgz`
+
+- **`SMOKE_V2_SHARED_DIST`**: Path to shared test utilities (auto-built if not set)
+  - Example: `shared/dist`
+
+### Local vs CI Execution
+
+**Locally:**
+
+- Tarballs auto-created on first run
+- Cached for subsequent runs (fast)
+- Run from any level: `sdk/js/`, `sdk/js/smoke/`, or scenario directory
+
+**In CI** (`.github/workflows/js.yaml`):
+
+1. **Build job**: Creates all tarballs (braintrust, otel, templates-nunjucks), uploads as artifacts
+2. **Smoke-discover job**: Auto-discovers all scenarios (local + integration)
+3. **Smoke-test job**: Downloads tarballs, runs all scenarios in parallel with `fail-fast: false`
+
+## Integration Scenarios
+
+Integration scenarios test SDK integrations and are located under `../../integrations/*/scenarios/`:
+
+### Templates-Nunjucks
+
+- **templates-nunjucks/basic-render**: Basic Nunjucks template rendering
+- **templates-nunjucks/deno**: Deno runtime with Nunjucks
+- **templates-nunjucks/jest**: Jest test runner with Nunjucks
+- **templates-nunjucks/nextjs**: Next.js integration with Nunjucks
+
+### OpenTelemetry (OTel)
+
+- **otel-js/otel-v1**: OpenTelemetry smoke test scenario (using shared test suite)
+
+Note: The `otel-js/otel-v1` and `otel-js/otel-v2` directories at the root of `integrations/otel-js/` are integration test environments (not smoke tests) and use a different test runner (vitest).
+
+All integration scenarios are automatically discovered and run alongside local scenarios.
+
 ## Design Principles
 
 ### Well-Known Tarball Paths
diff --git a/js/smoke/scenarios/browser-main-package/.gitignore b/js/smoke/scenarios/browser-main-package/.gitignore
new file mode 100644
index 000000000..2bbe28c25
--- /dev/null
+++ b/js/smoke/scenarios/browser-main-package/.gitignore
@@ -0,0 +1,5 @@
+node_modules/
+dist/
+package-lock.json
+test-results/
+playwright-report/
diff --git a/js/smoke/scenarios/browser-main-package/Makefile b/js/smoke/scenarios/browser-main-package/Makefile
new file mode 100644
index 000000000..704f7aa07
--- /dev/null
+++ b/js/smoke/scenarios/browser-main-package/Makefile
@@ -0,0 +1,14 @@
+.PHONY: install build test clean
+
+install:
+	npm install
+	npx playwright install --with-deps chromium
+
+build: install
+	node esbuild.config.mjs
+
+test: build
+	npx playwright test
+
+clean:
+	rm -rf node_modules dist package-lock.json
diff --git a/js/smoke/scenarios/browser-main-package/README.md b/js/smoke/scenarios/browser-main-package/README.md
new file mode 100644
index 000000000..581f3fbe7
--- /dev/null
+++ b/js/smoke/scenarios/browser-main-package/README.md
@@ -0,0 +1,64 @@
+# Browser Main Package Smoke Test
+
+This smoke test verifies that the informational message appears when using the browser build from the main `braintrust` package.
+
+## What This Tests
+
+When a user imports from the main `braintrust` package in a browser environment:
+
+```typescript
+import * as braintrust from "braintrust";
+```
+
+The bundler (via the `"browser"` field in package.json) will resolve to the browser build (`dist/browser.mjs`), which should:
+
+1. Show an informational console message suggesting `@braintrust/browser` for optimal use
+2. Provide working browser-safe implementations
+3. Not include Node.js modules
+
+## Test Structure
+
+- **src/browser-message-test.ts** - Browser test script that imports from main package
+- **pages/browser-message-test.html** - HTML page to run the test
+- **tests/browser-message.test.ts** - Playwright test that verifies the message
+
+## Running the Test
+
+```bash
+make test
+```
+
+Or step by step:
+
+```bash
+# Install dependencies
+make install
+
+# Build the test bundle
+make build
+
+# Run Playwright tests
+npx playwright test
+```
+
+## What Gets Verified
+
+✓ Import from main package works in browser
+✓ Basic functions are available (init, newId, traceable)
+✓ Informational message appears in console
+✓ Message mentions "@braintrust/browser" package
+✓ No Node.js module errors
+
+## Expected Console Output
+
+When the test runs, you should see:
+
+```
+Braintrust SDK Browser Build
+You are using a browser-compatible build from the main package.
+For optimal browser support consider:
+  npm install @braintrust/browser
+  import * as braintrust from "@braintrust/browser"
+```
+
+This message guides users toward the optimized `@braintrust/browser` package while ensuring the main package works correctly in browsers.
diff --git a/js/smoke/scenarios/browser-main-package/esbuild.config.mjs b/js/smoke/scenarios/browser-main-package/esbuild.config.mjs
new file mode 100644
index 000000000..681330c31
--- /dev/null
+++ b/js/smoke/scenarios/browser-main-package/esbuild.config.mjs
@@ -0,0 +1,18 @@
+import esbuild from "esbuild";
+import { rmSync } from "node:fs";
+
+rmSync("dist", { recursive: true, force: true });
+
+await esbuild.build({
+  entryPoints: ["src/browser-message-test.ts"],
+  bundle: true,
+  format: "esm",
+  outdir: "dist",
+  platform: "browser",
+  target: "es2022",
+  sourcemap: true,
+  mainFields: ["browser", "module", "main"],
+  external: [],
+});
+
+console.log("Build complete!");
diff --git a/js/smoke/scenarios/browser-main-package/mise.toml b/js/smoke/scenarios/browser-main-package/mise.toml
new file mode 100644
index 000000000..6a0493c69
--- /dev/null
+++ b/js/smoke/scenarios/browser-main-package/mise.toml
@@ -0,0 +1,2 @@
+[tools]
+node = "22"
diff --git a/js/smoke/scenarios/browser-main-package/package.json b/js/smoke/scenarios/browser-main-package/package.json
new file mode 100644
index 000000000..bd3bc537a
--- /dev/null
+++ b/js/smoke/scenarios/browser-main-package/package.json
@@ -0,0 +1,18 @@
+{
+  "name": "smoke-browser-main-package",
+  "version": "1.0.0",
+  "private": true,
+  "type": "module",
+  "description": "Smoke test for main package browser build with informational message",
+  "dependencies": {
+    "braintrust": "file:../../../artifacts/braintrust-latest.tgz",
+    "zod": "^4.3.5"
+  },
+  "devDependencies": {
+    "@playwright/test": "^1.51.1",
+    "@types/node": "^20.10.5",
+    "esbuild": "^0.27.2",
+    "http-server": "^14.1.1",
+    "typescript": "^5.4.4"
+  }
+}
diff --git a/js/smoke/scenarios/browser-main-package/pages/browser-message-test.html b/js/smoke/scenarios/browser-main-package/pages/browser-message-test.html
new file mode 100644
index 000000000..3f23e1f2e
--- /dev/null
+++ b/js/smoke/scenarios/browser-main-package/pages/browser-message-test.html
@@ -0,0 +1,17 @@
+<!doctype html>
+<html lang="en">
+  <head>
+    <meta charset="UTF-8" />
+    <meta name="viewport" content="width=device-width, initial-scale=1.0" />
+    <title>Braintrust Main Package Browser Build Test</title>
+  </head>
+  <body>
+    <h1>Braintrust Main Package Browser Build Test</h1>
+    <p>
+      This test verifies the informational message appears when using the
+      browser build from the main package.
+    </p>
+    <div id="output"></div>
+    <script type="module" src="/dist/browser-message-test.js"></script>
+  </body>
+</html>
diff --git a/js/smoke/scenarios/browser-main-package/playwright.config.ts b/js/smoke/scenarios/browser-main-package/playwright.config.ts
new file mode 100644
index 000000000..3cce5c28d
--- /dev/null
+++ b/js/smoke/scenarios/browser-main-package/playwright.config.ts
@@ -0,0 +1,26 @@
+import { defineConfig, devices } from "@playwright/test";
+
+export default defineConfig({
+  testDir: "./tests",
+  fullyParallel: false,
+  forbidOnly: !!process.env.CI,
+  retries: process.env.CI ? 2 : 0,
+  workers: 1,
+  reporter: "list",
+  use: {
+    baseURL: "http://localhost:8765",
+    trace: "on-first-retry",
+  },
+  projects: [
+    {
+      name: "chromium",
+      use: { ...devices["Desktop Chrome"] },
+    },
+  ],
+  webServer: {
+    command: "npx http-server -p 8765",
+    port: 8765,
+    reuseExistingServer: !process.env.CI,
+    timeout: 10000,
+  },
+});
diff --git a/js/smoke/scenarios/browser-main-package/src/browser-message-test.ts b/js/smoke/scenarios/browser-main-package/src/browser-message-test.ts
new file mode 100644
index 000000000..dd728e468
--- /dev/null
+++ b/js/smoke/scenarios/browser-main-package/src/browser-message-test.ts
@@ -0,0 +1,58 @@
+declare global {
+  interface Window {
+    __btBrowserMessageTest?: {
+      completed: boolean;
+      consoleMessages: string[];
+      importSuccessful: boolean;
+      hasInit: boolean;
+      hasNewId: boolean;
+      hasTraceable: boolean;
+    };
+  }
+}
+
+// Capture console.info messages BEFORE importing braintrust
+const capturedMessages: string[] = [];
+const originalConsoleInfo = console.info;
+console.info = (...args: any[]) => {
+  const message = args.join(" ");
+  capturedMessages.push(message);
+  originalConsoleInfo.apply(console, args);
+};
+
+// Import from main package browser export AFTER setting up console capture
+// This must be done dynamically to ensure console.info is overridden first
+const braintrust = await import("braintrust/browser");
+
+// Test that imports work
+const importSuccessful = true;
+const hasInit = typeof braintrust.init === "function";
+const hasNewId = typeof braintrust.newId === "function";
+const hasTraceable = typeof braintrust.traceable === "function";
+
+// Store results
+window.__btBrowserMessageTest = {
+  completed: true,
+  consoleMessages: capturedMessages,
+  importSuccessful,
+  hasInit,
+  hasNewId,
+  hasTraceable,
+};
+
+// Display results
+const output = document.getElementById("output");
+if (output) {
+  output.innerHTML = `
+    <h2>Test Results</h2>
+    <ul>
+      <li>Import successful: ${importSuccessful ? "✓" : "✗"}</li>
+      <li>Has init function: ${hasInit ? "✓" : "✗"}</li>
+      <li>Has newId function: ${hasNewId ? "✓" : "✗"}</li>
+      <li>Has traceable function: ${hasTraceable ? "✓" : "✗"}</li>
+      <li>Console messages captured: ${capturedMessages.length}</li>
+    </ul>
+    <h3>Console Messages:</h3>
+    <pre>${capturedMessages.join("\n")}</pre>
+  `;
+}
diff --git a/js/smoke/scenarios/browser-main-package/tests/browser-message.test.ts b/js/smoke/scenarios/browser-main-package/tests/browser-message.test.ts
new file mode 100644
index 000000000..d815136e3
--- /dev/null
+++ b/js/smoke/scenarios/browser-main-package/tests/browser-message.test.ts
@@ -0,0 +1,88 @@
+import { test, expect } from "@playwright/test";
+
+test.describe("Braintrust Main Package Browser Build", () => {
+  test("should display informational message when using browser build", async ({
+    page,
+    baseURL,
+  }) => {
+    const consoleMessages: string[] = [];
+
+    // Capture console.info messages
+    page.on("console", (msg) => {
+      if (msg.type() === "info") {
+        consoleMessages.push(msg.text());
+      } else if (msg.type() === "error") {
+        console.error(`[Browser Console Error] ${msg.text()}`);
+      }
+    });
+
+    page.on("pageerror", (error) => {
+      console.error("[Browser Page Error]", error.message);
+    });
+
+    // Load the test page
+    const response = await page.goto(
+      `${baseURL}/pages/browser-message-test.html`,
+      {
+        waitUntil: "domcontentloaded",
+        timeout: 10000,
+      },
+    );
+
+    if (!response || !response.ok()) {
+      throw new Error(`Failed to load page: ${response?.status()}`);
+    }
+
+    // Wait for test to complete
+    await page.waitForFunction(
+      () => {
+        return (window as any).__btBrowserMessageTest?.completed === true;
+      },
+      { timeout: 10000 },
+    );
+
+    // Get test results
+    const testResults = await page.evaluate(
+      () => (window as any).__btBrowserMessageTest,
+    );
+
+    // Log results for debugging
+    console.log("Test Results:", testResults);
+    console.log("Captured Console Messages:", consoleMessages);
+
+    // Assertions
+    expect(testResults).toBeTruthy();
+    expect(testResults.completed).toBe(true);
+    expect(testResults.importSuccessful).toBe(true);
+    expect(testResults.hasInit).toBe(true);
+    expect(testResults.hasNewId).toBe(true);
+    expect(testResults.hasTraceable).toBe(true);
+
+    // Expected message from browser-config.ts
+    const expectedMessage =
+      "This entrypoint is no longer supported.\n\n" +
+      "You should be using entrypoints:\n\n" +
+      "- `/workerd` (cloudflare envs)\n" +
+      "- `/edge-light` (next-js or other edge envs)\n\n" +
+      "If you'd like to use braintrust in the browser use the dedicated package: @braintrust/browser\n";
+
+    // Verify the full informational message appears in console
+    const hasInformationalMessage = consoleMessages.some(
+      (msg) => msg === expectedMessage,
+    );
+
+    expect(hasInformationalMessage).toBe(true);
+
+    // Also verify from captured messages in the page
+    const hasCapturedMessage = testResults.consoleMessages.some(
+      (msg: string) => msg === expectedMessage,
+    );
+
+    expect(hasCapturedMessage).toBe(true);
+
+    console.log("✓ Complete informational message verified");
+    console.log(
+      "✓ Main package browser build working correctly with full message",
+    );
+  });
+});
diff --git a/js/smoke/scenarios/browser-main-package/tsconfig.json b/js/smoke/scenarios/browser-main-package/tsconfig.json
new file mode 100644
index 000000000..d1677290d
--- /dev/null
+++ b/js/smoke/scenarios/browser-main-package/tsconfig.json
@@ -0,0 +1,16 @@
+{
+  "compilerOptions": {
+    "target": "ES2022",
+    "module": "ESNext",
+    "lib": ["ES2022", "DOM"],
+    "moduleResolution": "bundler",
+    "strict": true,
+    "esModuleInterop": true,
+    "skipLibCheck": true,
+    "forceConsistentCasingInFileNames": true,
+    "resolveJsonModule": true,
+    "isolatedModules": true,
+    "noEmit": true
+  },
+  "include": ["src/**/*", "tests/**/*"]
+}
diff --git a/js/smoke/scenarios/cloudflare-vite-hono-vite-dev-node-esm/src/worker-node-esm.ts b/js/smoke/scenarios/cloudflare-vite-hono-vite-dev-node-esm/src/worker-node-esm.ts
index 90f59075c..bfe08e49b 100644
--- a/js/smoke/scenarios/cloudflare-vite-hono-vite-dev-node-esm/src/worker-node-esm.ts
+++ b/js/smoke/scenarios/cloudflare-vite-hono-vite-dev-node-esm/src/worker-node-esm.ts
@@ -78,8 +78,9 @@ app.get("/api/test", async (c) => {
       testMustacheTemplate,
       expectFailure(
         testNunjucksTemplate,
-        (e) => e.message.includes("Disallowed in this environment"),
-        "Cloudflare Workers blocks dynamic code generation (eval/Function)",
+        (e: { message: string }) =>
+          e.message.includes("requires @braintrust/template-nunjucks"),
+        "Nunjucks requires separate package",
       ),
     ],
   });
diff --git a/js/smoke/scenarios/cloudflare-vite-hono-vite-dev/package.json b/js/smoke/scenarios/cloudflare-vite-hono-vite-dev/package.json
index 272211cad..8b0168d16 100644
--- a/js/smoke/scenarios/cloudflare-vite-hono-vite-dev/package.json
+++ b/js/smoke/scenarios/cloudflare-vite-hono-vite-dev/package.json
@@ -4,6 +4,7 @@
   "type": "module",
   "dependencies": {
     "braintrust": "file:../../../artifacts/braintrust-latest.tgz",
+    "@braintrust/browser": "file:../../../artifacts/braintrust-browser-latest.tgz",
     "hono": "^4.11.1",
     "react": "^19.2.1",
     "react-dom": "^19.2.1",
diff --git a/js/smoke/scenarios/cloudflare-vite-hono-vite-dev/src/worker.ts b/js/smoke/scenarios/cloudflare-vite-hono-vite-dev/src/worker.ts
index 29fbbbd41..887aa1d0d 100644
--- a/js/smoke/scenarios/cloudflare-vite-hono-vite-dev/src/worker.ts
+++ b/js/smoke/scenarios/cloudflare-vite-hono-vite-dev/src/worker.ts
@@ -28,7 +28,7 @@ import {
   testEvalSmoke,
 } from "../../../shared";
 
-import * as braintrust from "braintrust";
+import * as braintrust from "@braintrust/browser";
 
 const app = new Hono<{ Bindings: Env }>();
 
@@ -73,8 +73,9 @@ app.get("/api/test", async (c) => {
       testMustacheTemplate,
       expectFailure(
         testNunjucksTemplate,
-        (e) => e.message.includes("Nunjucks templating is not supported"),
-        "Nunjucks not supported in browser build",
+        (e: { message: string }) =>
+          e.message.includes("requires @braintrust/template-nunjucks"),
+        "Nunjucks requires separate package",
       ),
     ],
   });
diff --git a/js/smoke/scenarios/cloudflare-vite-hono-wrangler-dev/package.json b/js/smoke/scenarios/cloudflare-vite-hono-wrangler-dev/package.json
index c0edc8625..9a8899a7a 100644
--- a/js/smoke/scenarios/cloudflare-vite-hono-wrangler-dev/package.json
+++ b/js/smoke/scenarios/cloudflare-vite-hono-wrangler-dev/package.json
@@ -4,6 +4,7 @@
   "type": "module",
   "dependencies": {
     "braintrust": "file:../../../artifacts/braintrust-latest.tgz",
+    "@braintrust/browser": "file:../../../artifacts/braintrust-browser-latest.tgz",
     "hono": "^4.11.1",
     "zod": "^3.25.76"
   },
diff --git a/js/smoke/scenarios/cloudflare-vite-hono-wrangler-dev/src/worker.ts b/js/smoke/scenarios/cloudflare-vite-hono-wrangler-dev/src/worker.ts
index c440196ba..33b9cfe33 100644
--- a/js/smoke/scenarios/cloudflare-vite-hono-wrangler-dev/src/worker.ts
+++ b/js/smoke/scenarios/cloudflare-vite-hono-wrangler-dev/src/worker.ts
@@ -28,7 +28,7 @@ import {
   testEvalSmoke,
 } from "../../../shared";
 
-import * as braintrust from "braintrust";
+import * as braintrust from "@braintrust/browser";
 
 const app = new Hono<{ Bindings: Env }>();
 
@@ -73,8 +73,9 @@ app.get("/api/test", async (c) => {
       testMustacheTemplate,
       expectFailure(
         testNunjucksTemplate,
-        (e) => e.message.includes("Nunjucks templating is not supported"),
-        "Nunjucks not supported in browser build",
+        (e: { message: string }) =>
+          e.message.includes("requires @braintrust/template-nunjucks"),
+        "Nunjucks requires separate package",
       ),
     ],
   });
diff --git a/js/smoke/scenarios/cloudflare-worker-browser-compat/package.json b/js/smoke/scenarios/cloudflare-worker-browser-compat/package.json
index c39db0404..65ba9854f 100644
--- a/js/smoke/scenarios/cloudflare-worker-browser-compat/package.json
+++ b/js/smoke/scenarios/cloudflare-worker-browser-compat/package.json
@@ -4,6 +4,7 @@
   "type": "module",
   "dependencies": {
     "braintrust": "file:../../../artifacts/braintrust-latest.tgz",
+    "@braintrust/browser": "file:../../../artifacts/braintrust-browser-latest.tgz",
     "zod": "^3.25.76"
   },
   "devDependencies": {
diff --git a/js/smoke/scenarios/cloudflare-worker-browser-compat/src/worker.ts b/js/smoke/scenarios/cloudflare-worker-browser-compat/src/worker.ts
index a80533a28..28d7d810a 100644
--- a/js/smoke/scenarios/cloudflare-worker-browser-compat/src/worker.ts
+++ b/js/smoke/scenarios/cloudflare-worker-browser-compat/src/worker.ts
@@ -1,4 +1,4 @@
-import * as braintrust from "braintrust";
+import * as braintrust from "@braintrust/browser";
 import {
   runTests,
   expectFailure,
@@ -64,8 +64,9 @@ export default {
           testMustacheTemplate,
           expectFailure(
             testNunjucksTemplate,
-            (e) => e.message.includes("String template rendering. Disallowed"),
-            "Nunjucks evals not supported",
+            (e: { message: string }) =>
+              e.message.includes("requires @braintrust/template-nunjucks"),
+            "Nunjucks requires separate package",
           ),
         ],
       });
diff --git a/js/smoke/scenarios/cloudflare-worker-browser-no-compat/package.json b/js/smoke/scenarios/cloudflare-worker-browser-no-compat/package.json
index 5e8ae393f..438b44a00 100644
--- a/js/smoke/scenarios/cloudflare-worker-browser-no-compat/package.json
+++ b/js/smoke/scenarios/cloudflare-worker-browser-no-compat/package.json
@@ -4,6 +4,7 @@
   "type": "module",
   "dependencies": {
     "braintrust": "file:../../../artifacts/braintrust-latest.tgz",
+    "@braintrust/browser": "file:../../../artifacts/braintrust-browser-latest.tgz",
     "zod": "^3.25.76"
   },
   "devDependencies": {
diff --git a/js/smoke/scenarios/cloudflare-worker-browser-no-compat/src/worker.ts b/js/smoke/scenarios/cloudflare-worker-browser-no-compat/src/worker.ts
index 56e8c1cc1..328496ebb 100644
--- a/js/smoke/scenarios/cloudflare-worker-browser-no-compat/src/worker.ts
+++ b/js/smoke/scenarios/cloudflare-worker-browser-no-compat/src/worker.ts
@@ -1,4 +1,4 @@
-import * as braintrust from "braintrust";
+import * as braintrust from "@braintrust/browser";
 import {
   runTests,
   expectFailure,
@@ -64,8 +64,9 @@ export default {
           testMustacheTemplate,
           expectFailure(
             testNunjucksTemplate,
-            (e) => e.message.includes("Nunjucks templating is not supported"),
-            "Nunjucks not supported in browser build",
+            (e: { message: string }) =>
+              e.message.includes("requires @braintrust/template-nunjucks"),
+            "Nunjucks requires separate package",
           ),
         ],
       });
diff --git a/js/smoke/scenarios/cloudflare-worker-node-compat/src/worker.ts b/js/smoke/scenarios/cloudflare-worker-node-compat/src/worker.ts
index 17c8e186e..6fd2f7f01 100644
--- a/js/smoke/scenarios/cloudflare-worker-node-compat/src/worker.ts
+++ b/js/smoke/scenarios/cloudflare-worker-node-compat/src/worker.ts
@@ -64,8 +64,9 @@ export default {
           testMustacheTemplate,
           expectFailure(
             testNunjucksTemplate,
-            (e) => e.message.includes("Disallowed in this environment"),
-            "Cloudflare Workers blocks dynamic code generation (eval/Function)",
+            (e: { message: string }) =>
+              e.message.includes("requires @braintrust/template-nunjucks"),
+            "Nunjucks requires separate package",
           ),
         ],
       });
diff --git a/js/smoke/scenarios/cloudflare-worker-node-no-compat/src/worker.ts b/js/smoke/scenarios/cloudflare-worker-node-no-compat/src/worker.ts
index 8090a2fce..86a08c0cf 100644
--- a/js/smoke/scenarios/cloudflare-worker-node-no-compat/src/worker.ts
+++ b/js/smoke/scenarios/cloudflare-worker-node-no-compat/src/worker.ts
@@ -1,6 +1,7 @@
 import * as braintrust from "braintrust/node";
 import {
   runTests,
+  expectFailure,
   testBasicSpanLogging,
   testMultipleSpans,
   testDirectLogging,
@@ -61,7 +62,12 @@ export default {
           testCurrentSpan,
           testEvalSmoke,
           testMustacheTemplate,
-          testNunjucksTemplate,
+          expectFailure(
+            testNunjucksTemplate,
+            (e: { message: string }) =>
+              e.message.includes("requires @braintrust/template-nunjucks"),
+            "Nunjucks requires separate package",
+          ),
         ],
       });
 
diff --git a/js/smoke/scenarios/deno-browser/Makefile b/js/smoke/scenarios/deno-browser/Makefile
index 09ad4910d..8c95c70db 100644
--- a/js/smoke/scenarios/deno-browser/Makefile
+++ b/js/smoke/scenarios/deno-browser/Makefile
@@ -15,4 +15,5 @@ setup:
 	fi; \
 
 test: setup
-	deno test --sloppy-imports --allow-all tests/*.test.ts
+	@# Run only tests under the local tests/ directory
+	mise exec -- deno test --sloppy-imports --allow-all tests/*.test.ts
diff --git a/js/smoke/scenarios/deno-browser/deno.json b/js/smoke/scenarios/deno-browser/deno.json
index ab612b4d0..db0573ac5 100644
--- a/js/smoke/scenarios/deno-browser/deno.json
+++ b/js/smoke/scenarios/deno-browser/deno.json
@@ -2,7 +2,7 @@
   "imports": {
     "@std/assert": "jsr:@std/assert@^1.0.14",
     "@braintrust/smoke-test-shared": "jsr:@braintrust/smoke-test-shared",
-    "braintrust": "npm:braintrust/browser"
+    "@braintrust/browser": "npm:@braintrust/browser@^0.0.2-rc.0"
   },
   "nodeModulesDir": "auto",
   "links": [
diff --git a/js/smoke/scenarios/deno-browser/tests/shared-suite.test.ts b/js/smoke/scenarios/deno-browser/tests/shared-suite.test.ts
index 2c37b4f98..eb3dd0884 100644
--- a/js/smoke/scenarios/deno-browser/tests/shared-suite.test.ts
+++ b/js/smoke/scenarios/deno-browser/tests/shared-suite.test.ts
@@ -32,7 +32,7 @@ import {
   testNunjucksTemplate,
   testEvalSmoke,
 } from "@braintrust/smoke-test-shared";
-import * as braintrust from "braintrust";
+import * as braintrust from "@braintrust/browser";
 
 Deno.test("Run shared test suites (browser build)", async () => {
   const { failed } = await runTests({
@@ -65,8 +65,8 @@ Deno.test("Run shared test suites (browser build)", async () => {
       expectFailure(
         testNunjucksTemplate,
         (e: { message: string }) =>
-          e.message.includes("Nunjucks templating is not supported"),
-        "Nunjucks not supported in browser build",
+          e.message.includes("requires @braintrust/template-nunjucks"),
+        "Nunjucks requires separate package",
       ),
     ],
   });
diff --git a/js/smoke/scenarios/deno-node/Makefile b/js/smoke/scenarios/deno-node/Makefile
index 3a7c730a7..05babbc0f 100644
--- a/js/smoke/scenarios/deno-node/Makefile
+++ b/js/smoke/scenarios/deno-node/Makefile
@@ -15,4 +15,5 @@ setup:
 	fi; \
 
 test: setup
-	deno test --sloppy-imports --allow-all tests/*.test.ts
+	@# Run only tests under the local tests/ directory
+	mise exec -- deno test --sloppy-imports --allow-all tests/*.test.ts
diff --git a/js/smoke/scenarios/deno-node/tests/shared-suite.test.ts b/js/smoke/scenarios/deno-node/tests/shared-suite.test.ts
index 543312576..3286585cb 100644
--- a/js/smoke/scenarios/deno-node/tests/shared-suite.test.ts
+++ b/js/smoke/scenarios/deno-node/tests/shared-suite.test.ts
@@ -6,6 +6,7 @@
 import { assertEquals } from "@std/assert";
 import {
   runTests,
+  expectFailure,
   testBasicSpanLogging,
   testMultipleSpans,
   testDirectLogging,
@@ -61,7 +62,12 @@ Deno.test("Run shared test suites", async () => {
       testCurrentSpan,
       testEvalSmoke,
       testMustacheTemplate,
-      testNunjucksTemplate,
+      expectFailure(
+        testNunjucksTemplate,
+        (e: { message: string }) =>
+          e.message.includes("requires @braintrust/template-nunjucks"),
+        "Nunjucks requires separate package",
+      ),
     ],
   });
 
diff --git a/js/smoke/scenarios/jest-node/Makefile b/js/smoke/scenarios/jest-node/Makefile
index 22f859f8c..ccdff2cf0 100644
--- a/js/smoke/scenarios/jest-node/Makefile
+++ b/js/smoke/scenarios/jest-node/Makefile
@@ -36,4 +36,5 @@ setup:
 
 test: setup
 	@echo "==> Running jest-node tests"
-	npx jest
+	@# Run only tests under the local tests/ directory to avoid workspace-wide discovery
+	npx jest --passWithNoTests --roots ./tests
diff --git a/js/smoke/scenarios/jest-node/tests/shared-suite.test.js b/js/smoke/scenarios/jest-node/tests/shared-suite.test.js
index 33c2d24a4..13aeffdf4 100644
--- a/js/smoke/scenarios/jest-node/tests/shared-suite.test.js
+++ b/js/smoke/scenarios/jest-node/tests/shared-suite.test.js
@@ -1,5 +1,6 @@
 const {
   runTests,
+  expectFailure,
   testBasicSpanLogging,
   testMultipleSpans,
   testDirectLogging,
@@ -23,6 +24,7 @@ const {
   testBuildResolution,
   testMustacheTemplate,
   testNunjucksTemplate,
+  testEvalSmoke,
 } = require("../../../shared/dist/index.js");
 
 const braintrust = require("braintrust");
@@ -53,8 +55,13 @@ test("shared test suites pass in Jest", async () => {
       testAsyncLocalStorageTraced,
       testNestedTraced,
       testCurrentSpan,
+      testEvalSmoke,
       testMustacheTemplate,
-      testNunjucksTemplate,
+      expectFailure(
+        testNunjucksTemplate,
+        (e) => e.message.includes("requires @braintrust/template-nunjucks"),
+        "Nunjucks requires separate package",
+      ),
     ],
   });
 
diff --git a/js/smoke/scenarios/nextjs-instrumentation/package.json b/js/smoke/scenarios/nextjs-instrumentation/package.json
index e8faeef10..19528dbd4 100644
--- a/js/smoke/scenarios/nextjs-instrumentation/package.json
+++ b/js/smoke/scenarios/nextjs-instrumentation/package.json
@@ -8,6 +8,7 @@
   },
   "dependencies": {
     "braintrust": "file:../../../artifacts/braintrust-latest.tgz",
+    "@braintrust/browser": "file:../../../artifacts/braintrust-browser-latest.tgz",
     "@braintrust/otel": "file:../../../artifacts/braintrust-otel-latest.tgz",
     "@opentelemetry/api": "^1.9.0",
     "@opentelemetry/api-logs": "^0.200.0",
diff --git a/js/smoke/scenarios/nextjs-instrumentation/src/app/api/smoke-test/edge/route.ts b/js/smoke/scenarios/nextjs-instrumentation/src/app/api/smoke-test/edge/route.ts
index c0bf8769c..79beb7dff 100644
--- a/js/smoke/scenarios/nextjs-instrumentation/src/app/api/smoke-test/edge/route.ts
+++ b/js/smoke/scenarios/nextjs-instrumentation/src/app/api/smoke-test/edge/route.ts
@@ -32,7 +32,7 @@ import {
   testEvalSmoke,
 } from "../../../../../../../shared";
 
-import * as braintrust from "braintrust";
+import * as braintrust from "@braintrust/browser";
 
 export const runtime = "edge";
 
@@ -68,8 +68,9 @@ export async function GET() {
       testMustacheTemplate,
       expectFailure(
         testNunjucksTemplate,
-        (e) => e.message.includes("Nunjucks templating is not supported"),
-        "Nunjucks not supported in Edge Runtime",
+        (e: { message: string }) =>
+          e.message.includes("requires @braintrust/template-nunjucks"),
+        "Nunjucks requires separate package",
       ),
     ],
   });
diff --git a/js/smoke/scenarios/nextjs-instrumentation/src/app/api/smoke-test/node/route.ts b/js/smoke/scenarios/nextjs-instrumentation/src/app/api/smoke-test/node/route.ts
index 1730617da..7c86e8440 100644
--- a/js/smoke/scenarios/nextjs-instrumentation/src/app/api/smoke-test/node/route.ts
+++ b/js/smoke/scenarios/nextjs-instrumentation/src/app/api/smoke-test/node/route.ts
@@ -5,6 +5,7 @@
 import { NextResponse } from "next/server";
 import {
   runTests,
+  expectFailure,
   testBasicSpanLogging,
   testMultipleSpans,
   testDirectLogging,
@@ -65,7 +66,12 @@ export async function GET() {
       testCurrentSpan,
       testEvalSmoke,
       testMustacheTemplate,
-      testNunjucksTemplate,
+      expectFailure(
+        testNunjucksTemplate,
+        (e: { message: string }) =>
+          e.message.includes("requires @braintrust/template-nunjucks"),
+        "Nunjucks requires separate package",
+      ),
     ],
   });
 
diff --git a/js/smoke/scenarios/playwright-browser/package.json b/js/smoke/scenarios/playwright-browser/package.json
index 49818a121..e703f5b2d 100644
--- a/js/smoke/scenarios/playwright-browser/package.json
+++ b/js/smoke/scenarios/playwright-browser/package.json
@@ -6,6 +6,7 @@
   "description": "Playwright browser smoke test for Braintrust SDK",
   "dependencies": {
     "braintrust": "file:../../../artifacts/braintrust-latest.tgz",
+    "@braintrust/browser": "file:../../../artifacts/braintrust-browser-latest.tgz",
     "zod": "^4.3.5"
   },
   "devDependencies": {
diff --git a/js/smoke/scenarios/playwright-browser/src/browser-tests.ts b/js/smoke/scenarios/playwright-browser/src/browser-tests.ts
index e56a78d0a..f28a9ada7 100644
--- a/js/smoke/scenarios/playwright-browser/src/browser-tests.ts
+++ b/js/smoke/scenarios/playwright-browser/src/browser-tests.ts
@@ -1,4 +1,4 @@
-import * as braintrust from "braintrust";
+import * as braintrust from "@braintrust/browser";
 import {
   runTests,
   expectFailure,
@@ -84,8 +84,9 @@ async function runAllTestSuites() {
       testMustacheTemplate,
       expectFailure(
         testNunjucksTemplate,
-        (e) => e.message.includes("Nunjucks templating is not supported"),
-        "Nunjucks not supported in browser build",
+        (e: { message: string }) =>
+          e.message.includes("requires @braintrust/template-nunjucks"),
+        "Nunjucks requires separate package",
       ),
     ],
   });
diff --git a/js/smoke/scenarios/playwright-browser/tests/browser.test.ts b/js/smoke/scenarios/playwright-browser/tests/browser.test.ts
index fec302726..42dd1a9c5 100644
--- a/js/smoke/scenarios/playwright-browser/tests/browser.test.ts
+++ b/js/smoke/scenarios/playwright-browser/tests/browser.test.ts
@@ -110,11 +110,19 @@ test.describe("Braintrust SDK Browser Tests", () => {
         name: `All tests (${smoke.sections.tests.passed} passed)`,
       });
     } else {
+      // Extract individual test failures for better error reporting
+      const failureDetails = smoke.sections.tests.failures
+        .map(
+          (f) =>
+            `  • ${f.testName}: ${f.error}${f.message ? ` (${f.message})` : ""}`,
+        )
+        .join("\n");
+
       results.push({
         status: "fail",
         name: "All tests",
         error: {
-          message: `Completed: ${smoke.sections.tests.completed}, Passed: ${smoke.sections.tests.passed}, Failed: ${smoke.sections.tests.failed}`,
+          message: `Completed: ${smoke.sections.tests.completed}, Passed: ${smoke.sections.tests.passed}, Failed: ${smoke.sections.tests.failed}\n\nFailed tests:\n${failureDetails}`,
         },
       });
     }
diff --git a/js/smoke/shared/package-lock.json b/js/smoke/shared/package-lock.json
index f67d631b2..32ad0c26b 100644
--- a/js/smoke/shared/package-lock.json
+++ b/js/smoke/shared/package-lock.json
@@ -933,6 +933,7 @@
       "dev": true,
       "hasInstallScript": true,
       "license": "MIT",
+      "peer": true,
       "bin": {
         "esbuild": "bin/esbuild"
       },
@@ -1125,6 +1126,7 @@
       "integrity": "sha512-5gTmgEY/sqK6gFXLIsQNH19lWb4ebPDLA4SdLP7dsWkIXHWlG66oPuVvXSGFPppYZz8ZDZq0dYYrbHfBCVUb1Q==",
       "dev": true,
       "license": "MIT",
+      "peer": true,
       "engines": {
         "node": ">=12"
       },
@@ -1419,6 +1421,7 @@
       "integrity": "sha512-jl1vZzPDinLr9eUt3J/t7V6FgNEw9QjvBPdysz9KfQDD41fQrC2Y4vKQdiaUpFT4bXlb1RHhLpp8wtm6M5TgSw==",
       "dev": true,
       "license": "Apache-2.0",
+      "peer": true,
       "bin": {
         "tsc": "bin/tsc",
         "tsserver": "bin/tsserver"
diff --git a/js/smoke/shared/src/helpers/register.ts b/js/smoke/shared/src/helpers/register.ts
index 663481b5e..9b45d0126 100644
--- a/js/smoke/shared/src/helpers/register.ts
+++ b/js/smoke/shared/src/helpers/register.ts
@@ -120,6 +120,7 @@ export interface RunTestsOptions {
   name: string;
   braintrust: BraintrustModule;
   tests: TestFn[];
+  skipCoverage?: boolean;
 }
 
 export interface TestRunResults {
@@ -142,6 +143,7 @@ export async function runTests({
   name,
   braintrust,
   tests,
+  skipCoverage = false,
 }: RunTestsOptions): Promise<TestRunResults> {
   const results: TestResult[] = [];
 
@@ -149,7 +151,9 @@ export async function runTests({
     results.push(await test(braintrust));
   }
 
-  results.push(validateCoverage(results));
+  if (!skipCoverage) {
+    results.push(validateCoverage(results));
+  }
 
   displayTestResults({ scenarioName: name, results });
 
diff --git a/js/src/browser-config.ts b/js/src/browser-config.ts
index 2607a4ec1..718ec83cb 100644
--- a/js/src/browser-config.ts
+++ b/js/src/browser-config.ts
@@ -1,3 +1,6 @@
+// Browser-safe isomorph that noops Node.js features
+// This file is only used for the /browser, /edge-light, /workerd exports
+
 import iso from "./isomorph";
 import { _internalSetInitialState } from "./logger";
 
@@ -10,13 +13,30 @@ declare global {
 }
 // End copied code
 
+let messageShown = false;
 let browserConfigured = false;
-export function configureBrowser() {
+
+/**
+ * Configure the isomorph for browser environments.
+ */
+export function configureBrowser(): void {
   if (browserConfigured) {
     return;
   }
 
-  // Set build type indicator
+  // Show informational message once
+  if (!messageShown && typeof console !== "undefined") {
+    console.info(
+      "This entrypoint is no longer supported.\n\n" +
+        "You should be using entrypoints:\n\n" +
+        "- `/workerd` (cloudflare envs)\n" +
+        "- `/edge-light` (next-js or other edge envs)\n\n" +
+        "If you'd like to use braintrust in the browser use the dedicated package: @braintrust/browser\n",
+    );
+    messageShown = true;
+  }
+
+  // Configure browser-safe implementations
   iso.buildType = "browser";
 
   try {
@@ -34,12 +54,6 @@ export function configureBrowser() {
     return process.env[name];
   };
 
-  iso.renderNunjucksString = () => {
-    throw new Error(
-      "Nunjucks templating is not supported in this build. Use templateFormat: 'mustache' (or omit templateFormat).",
-    );
-  };
-
   // Implement browser-compatible hash function using a simple hash algorithm
   iso.hash = (data: string): string => {
     // Simple hash function for browser compatibility
diff --git a/js/src/browser.ts b/js/src/browser.ts
index 706b2bb4b..9f4f756d1 100644
--- a/js/src/browser.ts
+++ b/js/src/browser.ts
@@ -1,7 +1,16 @@
+/**
+ * Browser-compatible build of the Braintrust SDK.
+ *
+ * This build uses a noop isomorph that provides browser-safe implementations
+ * for Node.js-specific features.
+ *
+ * For optimal browser support with AsyncLocalStorage polyfill, consider:
+ *   npm install @braintrust/browser
+ *   import * as braintrust from '@braintrust/browser';
+ */
+
 import { configureBrowser } from "./browser-config";
 
 configureBrowser();
 
-// eslint-disable-next-line no-restricted-syntax -- already enforced in exports
 export * from "./exports";
-export * as default from "./exports";
diff --git a/js/src/exports.ts b/js/src/exports.ts
index fee5d4b43..420e1bd03 100644
--- a/js/src/exports.ts
+++ b/js/src/exports.ts
@@ -103,12 +103,26 @@ export {
   registerOtelFlush,
 } from "./logger";
 
+// Internal isomorph layer for platform-specific implementations
+import _internalIso from "./isomorph";
+export { _internalIso };
+
 export {
   isTemplateFormat,
   parseTemplateFormat,
   renderTemplateContent,
 } from "./template/renderer";
-export type { TemplateFormat } from "./template/renderer";
+export type { TemplateFormat } from "./template/registry";
+
+export type {
+  TemplateRenderer,
+  TemplateRendererPlugin,
+} from "./template/registry";
+export {
+  registerTemplatePlugin,
+  getTemplateRenderer,
+  templateRegistry,
+} from "./template/registry";
 
 export type { InvokeFunctionArgs, InvokeReturn } from "./functions/invoke";
 export { initFunction, invoke } from "./functions/invoke";
diff --git a/js/src/framework.test.ts b/js/src/framework.test.ts
index 62129fe17..0b3c7f7d8 100644
--- a/js/src/framework.test.ts
+++ b/js/src/framework.test.ts
@@ -1075,9 +1075,10 @@ describe("framework2 metadata support", () => {
       // Check that template_format is stored at the top level of prompt data
       expect(prompt.templateFormat).toBe("nunjucks");
 
-      // Verify it renders correctly
-      const result = prompt.build({ name: "World" });
-      expect(result.messages[0].content).toBe("Hello World");
+      // Verify it requires the addon to render
+      expect(() => prompt.build({ name: "World" })).toThrow(
+        "Nunjucks templating requires @braintrust/template-nunjucks. Install and import it to enable templateFormat: 'nunjucks'.",
+      );
     });
   });
 });
diff --git a/js/src/isomorph.ts b/js/src/isomorph.ts
index 690fdcb38..eef739889 100644
--- a/js/src/isomorph.ts
+++ b/js/src/isomorph.ts
@@ -75,13 +75,6 @@ export interface Common {
   // zlib (promisified and type-erased).
   gunzip?: (data: any) => Promise<any>;
   gzip?: (data: any) => Promise<any>;
-
-  // Nunjucks template rendering (lints if strict is true)
-  renderNunjucksString: (
-    template: string,
-    variables: Record<string, unknown>,
-    options?: { strict?: boolean },
-  ) => string;
 }
 
 const iso: Common = {
@@ -92,11 +85,6 @@ const iso: Common = {
   getCallerLocation: () => undefined,
   newAsyncLocalStorage: <T>() => new DefaultAsyncLocalStorage<T>(),
   processOn: (_0, _1) => {},
-  renderNunjucksString: () => {
-    throw new Error(
-      "Nunjucks templating is not supported in this build. Use templateFormat: 'mustache' (or omit templateFormat).",
-    );
-  },
   basename: (filepath: string) => filepath.split(/[\\/]/).pop() || filepath,
   writeln: (text: string) => console.log(text),
 };
diff --git a/js/src/logger.test.ts b/js/src/logger.test.ts
index 7123985ed..a9ad24bce 100644
--- a/js/src/logger.test.ts
+++ b/js/src/logger.test.ts
@@ -209,30 +209,16 @@ describe("prompt.build structured output templating", () => {
       false,
     );
 
-    const result = prompt.build(
-      {
-        user: { name: "ada" },
-      },
-      { templateFormat: "nunjucks" },
-    );
-
-    expect(result).toMatchObject({
-      response_format: {
-        type: "json_schema",
-        json_schema: {
-          name: "schema",
-          schema: {
-            type: "object",
-            properties: {
-              greeting: {
-                type: "string",
-                description: "Hello ADA",
-              },
-            },
-          },
+    expect(() =>
+      prompt.build(
+        {
+          user: { name: "ada" },
         },
-      },
-    });
+        { templateFormat: "nunjucks" },
+      ),
+    ).toThrow(
+      "Nunjucks templating requires @braintrust/template-nunjucks. Install and import it to enable templateFormat: 'nunjucks'.",
+    );
   });
 
   test("prompt.build with structured output templating", () => {
diff --git a/js/src/logger.ts b/js/src/logger.ts
index 9d1838dde..b1beb1548 100644
--- a/js/src/logger.ts
+++ b/js/src/logger.ts
@@ -75,8 +75,8 @@ import Mustache from "mustache";
 import {
   parseTemplateFormat,
   renderTemplateContent,
-  type TemplateFormat,
 } from "./template/renderer";
+import type { TemplateFormat } from "./template/registry";
 
 import { z, ZodError } from "zod/v3";
 import {
@@ -6497,25 +6497,15 @@ function renderTemplatedObject(
   options: { strict?: boolean; templateFormat: TemplateFormat },
 ): unknown {
   if (typeof obj === "string") {
-    const strict = !!options.strict;
-    if (options.templateFormat === "nunjucks") {
-      return iso.renderNunjucksString(obj, args, { strict });
-    }
-    if (options.templateFormat === "mustache") {
-      if (strict) {
-        lintMustacheTemplate(obj, args);
-      }
-      return Mustache.render(obj, args, undefined, {
-        escape: (value) => {
-          if (typeof value === "string") {
-            return value;
-          } else {
-            return JSON.stringify(value);
-          }
-        },
-      });
-    }
-    return obj;
+    return renderTemplateContent(
+      obj,
+      args,
+      (value) => (typeof value === "string" ? value : JSON.stringify(value)),
+      {
+        strict: options.strict,
+        templateFormat: options.templateFormat,
+      },
+    );
   } else if (isArray(obj)) {
     return obj.map((item) => renderTemplatedObject(item, args, options));
   } else if (isObject(obj)) {
diff --git a/js/src/node.ts b/js/src/node.ts
index df453a3a8..2351c6ca4 100644
--- a/js/src/node.ts
+++ b/js/src/node.ts
@@ -9,8 +9,6 @@ import iso from "./isomorph";
 import { getRepoInfo, getPastNAncestors } from "./gitutil";
 import { getCallerLocation } from "./stackutil";
 import { _internalSetInitialState } from "./logger";
-import { renderNunjucksString as nunjucksRender } from "./template/nunjucks-env";
-import { lintTemplate as nunjucksLint } from "./template/nunjucks-utils";
 import { promisify } from "node:util";
 import * as zlib from "node:zlib";
 
@@ -26,15 +24,6 @@ export function configureNode() {
   iso.processOn = (event: string, handler: (code: unknown) => void) => {
     process.on(event, handler);
   };
-  iso.renderNunjucksString = (template, variables, options = {}) => {
-    const strict = options.strict ?? false;
-
-    if (strict) {
-      nunjucksLint(template, variables);
-    }
-
-    return nunjucksRender(template, variables, { strict });
-  };
   iso.basename = path.basename;
   iso.writeln = (text: string) => process.stdout.write(text + "\n");
   iso.pathJoin = path.join;
diff --git a/js/src/prompt.test.ts b/js/src/prompt.test.ts
index c822a39d7..849158cc2 100644
--- a/js/src/prompt.test.ts
+++ b/js/src/prompt.test.ts
@@ -168,8 +168,9 @@ describe("prompt template_format", () => {
       true,
     );
 
-    const result = prompt.build({ name: "World" });
-    expect(result.messages[0].content).toBe("Hello World");
+    expect(() => prompt.build({ name: "World" })).toThrow(
+      "Nunjucks templating requires @braintrust/template-nunjucks. Install and import it to enable templateFormat: 'nunjucks'.",
+    );
   });
 
   test("defaults to mustache when no templateFormat specified", () => {
@@ -258,8 +259,11 @@ describe("prompt template_format", () => {
       true,
     );
 
-    const result = prompt.build({ text: "Hello" }, { flavor: "completion" });
-    expect(result.prompt).toBe("Complete this: Hello");
+    expect(() =>
+      prompt.build({ text: "Hello" }, { flavor: "completion" }),
+    ).toThrow(
+      "Nunjucks templating requires @braintrust/template-nunjucks. Install and import it to enable templateFormat: 'nunjucks'.",
+    );
   });
 });
 
@@ -298,10 +302,9 @@ describe("prompt template_format (unconfigured/browser-like)", () => {
     );
 
     expect(() => prompt.build({ name: "World" })).toThrowError(
-      /Nunjucks templating is not supported in this build/,
+      /Nunjucks templating requires @braintrust\/template-nunjucks/,
     );
   });
-
   test("throws unsupported error after configureBrowser()", async () => {
     vi.resetModules();
     const { configureBrowser } = await import("./browser-config");
@@ -339,7 +342,7 @@ describe("prompt template_format (unconfigured/browser-like)", () => {
     );
 
     expect(() => prompt.build({ name: "World" })).toThrowError(
-      /Nunjucks templating is not supported in this build/,
+      /Nunjucks templating requires @braintrust\/template-nunjucks/,
     );
   });
 });
diff --git a/js/src/template/nunjucks-env.ts b/js/src/template/nunjucks-env.ts
deleted file mode 100644
index 16232f72b..000000000
--- a/js/src/template/nunjucks-env.ts
+++ /dev/null
@@ -1,48 +0,0 @@
-import { nunjucks } from "./nunjucks";
-import type { Environment as NunjucksEnvironment } from "nunjucks";
-import { SyncLazyValue } from "../util";
-
-const createNunjucksEnv = (throwOnUndefined: boolean): NunjucksEnvironment => {
-  return new nunjucks.Environment(null, {
-    autoescape: true,
-    throwOnUndefined,
-  });
-};
-
-const nunjucksEnv = new SyncLazyValue<NunjucksEnvironment>(() =>
-  createNunjucksEnv(false),
-);
-
-const nunjucksStrictEnv = new SyncLazyValue<NunjucksEnvironment>(() =>
-  createNunjucksEnv(true),
-);
-
-export function getNunjucksEnv(options?: {
-  strict?: boolean;
-}): NunjucksEnvironment {
-  const strict = options?.strict ?? false;
-  return strict ? nunjucksStrictEnv.get() : nunjucksEnv.get();
-}
-
-export function renderNunjucksString(
-  template: string,
-  variables: Record<string, unknown>,
-  options?: { strict?: boolean },
-): string {
-  const strict = options?.strict ?? false;
-  try {
-    return getNunjucksEnv({ strict }).renderString(template, variables);
-  } catch (error) {
-    if (
-      error instanceof Error &&
-      error.message.includes(
-        "Code generation from strings disallowed for this context",
-      )
-    ) {
-      throw new Error(
-        `String template rendering. Disallowed in this environment for security reasons. Try a different template renderer. Original error: ${error.message}`,
-      );
-    }
-    throw error;
-  }
-}
diff --git a/js/src/template/nunjucks-render.test.ts b/js/src/template/nunjucks-render.test.ts
deleted file mode 100644
index e6dd85ae1..000000000
--- a/js/src/template/nunjucks-render.test.ts
+++ /dev/null
@@ -1,215 +0,0 @@
-import { describe, test, expect } from "vitest";
-import { lintTemplate } from "./nunjucks-utils";
-import { getNunjucksEnv } from "./nunjucks-env";
-
-function getEnv() {
-  return getNunjucksEnv({ strict: false });
-}
-
-function getStrictEnv() {
-  return getNunjucksEnv({ strict: true });
-}
-
-describe("nunjucks rendering", () => {
-  test("renders variable and control structures", () => {
-    const env = getEnv();
-    const out = env.renderString(
-      "Hello {{ name | upper }} {% if age > 18 %}Adult{% else %}Minor{% endif %}",
-      { name: "alice", age: 30 },
-    );
-    expect(out).toBe("Hello ALICE Adult");
-  });
-
-  test("loops render", () => {
-    const env = getEnv();
-    const out = env.renderString(
-      `{% for item in items %}{{ item }},{% endfor %}`,
-      { items: ["a", "b"] },
-    );
-    expect(out).toBe("a,b,");
-  });
-
-  test("strict mode throws for missing top-level variable", () => {
-    const env = getStrictEnv();
-    const tpl = "Hello {{ name }}";
-    expect(() => env.renderString(tpl, { user: "x" })).toThrow();
-  });
-
-  test("strict mode passes for defined variable and filters", () => {
-    const env = getStrictEnv();
-    const tpl = "Hello {{ name | upper }}";
-    expect(() => env.renderString(tpl, { name: "alice" })).not.toThrow();
-  });
-
-  test("strict mode: for over undefined is empty (does not throw)", () => {
-    const env = getStrictEnv();
-    const tpl = `{% for item in items %}{{ item }}{% endfor %}`;
-    expect(() => env.renderString(tpl, { items: [1, 2, 3] })).not.toThrow();
-    expect(() => env.renderString(tpl, {})).not.toThrow();
-  });
-
-  test("strict mode: nested path with numeric index using brackets", () => {
-    const env = getStrictEnv();
-    const tpl = `{{ user.addresses[2].city }}`;
-    const ok = { user: { addresses: [{}, {}, { city: "SF" }] } };
-    expect(() => env.renderString(tpl, ok)).not.toThrow();
-    const bad = { user: {} };
-    expect(() => env.renderString(tpl, bad)).toThrow();
-  });
-
-  test("renders nested object properties", () => {
-    const env = getEnv();
-    const out = env.renderString("{{ user.profile.name }}", {
-      user: { profile: { name: "Alice" } },
-    });
-    expect(out).toBe("Alice");
-  });
-
-  test("renders multiple variables with context", () => {
-    const env = getEnv();
-    const out = env.renderString(
-      "{{ firstName }} {{ lastName }} is {{ age }} years old",
-      { firstName: "Bob", lastName: "Smith", age: 25 },
-    );
-    expect(out).toBe("Bob Smith is 25 years old");
-  });
-
-  test("renders with string concatenation", () => {
-    const env = getEnv();
-    const out = env.renderString("{{ greeting ~ ' ' ~ name }}", {
-      greeting: "Hello",
-      name: "World",
-    });
-    expect(out).toBe("Hello World");
-  });
-
-  test("renders numeric operations", () => {
-    const env = getEnv();
-    const out = env.renderString("Total: {{ price * quantity }}", {
-      price: 10,
-      quantity: 3,
-    });
-    expect(out).toBe("Total: 30");
-  });
-
-  test("renders with filters and context", () => {
-    const env = getEnv();
-    const out = env.renderString("{{ message | upper | trim }}", {
-      message: "  hello world  ",
-    });
-    expect(out).toBe("HELLO WORLD");
-  });
-
-  test("renders array elements with index", () => {
-    const env = getEnv();
-    const out = env.renderString(
-      "First: {{ items[0] }}, Last: {{ items[2] }}",
-      {
-        items: ["apple", "banana", "cherry"],
-      },
-    );
-    expect(out).toBe("First: apple, Last: cherry");
-  });
-
-  test("renders nested arrays and objects", () => {
-    const env = getEnv();
-    const out = env.renderString(
-      "{{ users[0].name }} from {{ users[0].city }}",
-      {
-        users: [
-          { name: "John", city: "NYC" },
-          { name: "Jane", city: "LA" },
-        ],
-      },
-    );
-    expect(out).toBe("John from NYC");
-  });
-
-  test("renders with default filter", () => {
-    const env = getEnv();
-    const out1 = env.renderString("{{ name | default('Guest') }}", {
-      name: "Alice",
-    });
-    expect(out1).toBe("Alice");
-    const out2 = env.renderString("{{ name | default('Guest') }}", {});
-    expect(out2).toBe("Guest");
-  });
-
-  test("renders ternary expressions", () => {
-    const env = getEnv();
-    const out1 = env.renderString("{{ user.name if user else 'Anonymous' }}", {
-      user: { name: "Alice" },
-    });
-    expect(out1).toBe("Alice");
-    const out2 = env.renderString(
-      "{{ user.name if user else 'Anonymous' }}",
-      {},
-    );
-    expect(out2).toBe("Anonymous");
-  });
-
-  test("renders with multiple filters chained", () => {
-    const env = getEnv();
-    const out = env.renderString("{{ text | lower | trim }}", {
-      text: "  HELLO WORLD  ",
-    });
-    expect(out).toBe("hello world");
-  });
-
-  test("renders complex nested context", () => {
-    const env = getEnv();
-    const out = env.renderString(
-      "{{ order.customer.name }} ordered {{ order.items[0].name }} for ${{ order.total }}",
-      {
-        order: {
-          customer: { name: "Alice" },
-          items: [{ name: "Widget", price: 10 }],
-          total: 10,
-        },
-      },
-    );
-    expect(out).toBe("Alice ordered Widget for $10");
-  });
-
-  test("renders with length filter on arrays", () => {
-    const env = getEnv();
-    const out = env.renderString("You have {{ items | length }} items", {
-      items: ["a", "b", "c", "d"],
-    });
-    expect(out).toBe("You have 4 items");
-  });
-
-  test("renders with join filter", () => {
-    const env = getEnv();
-    const out = env.renderString("{{ tags | join(', ') }}", {
-      tags: ["red", "green", "blue"],
-    });
-    expect(out).toBe("red, green, blue");
-  });
-});
-
-describe("nunjucks lintTemplate", () => {
-  test("passes for valid template syntax", () => {
-    expect(() => lintTemplate("Hello {{ user.name }}", {})).toThrow();
-  });
-
-  test("passes for valid template with loops", () => {
-    expect(() =>
-      lintTemplate(`{% for item in items %}{{ item }}{% endfor %}`, {}),
-    ).not.toThrow();
-  });
-
-  test("passes for valid template with conditionals", () => {
-    expect(() =>
-      lintTemplate(`{% if user %}{{ user.name }}{% endif %}`, {}),
-    ).not.toThrow();
-  });
-
-  test("throws for invalid template syntax", () => {
-    expect(() => lintTemplate("{{ unclosed", {})).toThrow();
-  });
-
-  test("throws for mismatched tags", () => {
-    expect(() => lintTemplate("{% if x %}{% endfor %}", {})).toThrow();
-  });
-});
diff --git a/js/src/template/nunjucks-utils.ts b/js/src/template/nunjucks-utils.ts
deleted file mode 100644
index 7afd682cd..000000000
--- a/js/src/template/nunjucks-utils.ts
+++ /dev/null
@@ -1,6 +0,0 @@
-import { getNunjucksEnv } from "./nunjucks-env";
-
-export function lintTemplate(template: string, context: any): void {
-  const env = getNunjucksEnv({ strict: true });
-  env.renderString(template, context);
-}
diff --git a/js/src/template/nunjucks.ts b/js/src/template/nunjucks.ts
deleted file mode 100644
index a7a60ffa0..000000000
--- a/js/src/template/nunjucks.ts
+++ /dev/null
@@ -1,3 +0,0 @@
-import * as nunjucksNodeModule from "nunjucks";
-
-export const nunjucks = nunjucksNodeModule;
diff --git a/js/src/template/registry.ts b/js/src/template/registry.ts
new file mode 100644
index 000000000..a71817c7e
--- /dev/null
+++ b/js/src/template/registry.ts
@@ -0,0 +1,161 @@
+import Mustache from "mustache";
+
+import { lintTemplate as lintMustacheTemplate } from "./mustache-utils";
+
+export type TemplateFormat = "mustache" | "nunjucks" | "none";
+
+export interface TemplateRenderer {
+  render: (
+    template: string,
+    variables: Record<string, unknown>,
+    escape: (v: unknown) => string,
+    strict: boolean,
+  ) => string;
+  lint?: (template: string, variables: Record<string, unknown>) => void;
+}
+
+/**
+ * A template renderer plugin that can be registered with Braintrust.
+ *
+ * Plugins provide support for different template engines (e.g., Nunjucks).
+ * They use a factory pattern where the plugin is registered once, then activated with specific
+ * configuration options when needed.
+ *
+ * @example
+ * ```typescript
+ * import type { TemplateRendererPlugin } from "braintrust";
+ *
+ * export const myPlugin: TemplateRendererPlugin = {
+ *   name: "my-template-engine",
+ *   version: "1.0.0",
+ *   defaultOptions: { strict: false },
+ *   createRenderer(options?: unknown) {
+ *     const opts = options ?? this.defaultOptions;
+ *     return {
+ *       render(template, variables, escape, strict) {
+ *         // Your rendering logic here
+ *       }
+ *     };
+ *   }
+ * };
+ * ```
+ */
+export interface TemplateRendererPlugin {
+  /**
+   * Unique identifier for this plugin.
+   * Must match the format string used in `templateFormat` option.
+   */
+  name: string;
+
+  /**
+   * Factory function that creates a renderer instance.
+   *
+   * @param options - If not provided, `defaultOptions` is used.
+   * @returns A configured TemplateRenderer instance
+   */
+  createRenderer: () => TemplateRenderer;
+
+  /**
+   * Default configuration options for this plugin.
+   */
+  defaultOptions?: unknown;
+}
+
+class TemplatePluginRegistry {
+  private plugins = new Map<
+    string,
+    { plugin: TemplateRendererPlugin; renderer?: TemplateRenderer }
+  >();
+
+  register(plugin: TemplateRendererPlugin): void {
+    if (this.plugins.has(plugin.name)) {
+      console.warn(
+        `Template plugin '${plugin.name}' already registered, overwriting`,
+      );
+    }
+
+    const entry = {
+      plugin,
+      renderer:
+        plugin.defaultOptions !== undefined
+          ? plugin.createRenderer()
+          : undefined,
+    };
+
+    this.plugins.set(plugin.name, entry);
+  }
+
+  getAvailable(): string[] {
+    return Array.from(this.plugins.keys());
+  }
+
+  get(name: string): TemplateRenderer | undefined {
+    return this.plugins.get(name)?.renderer;
+  }
+
+  isRegistered(name: string): boolean {
+    return this.plugins.has(name);
+  }
+}
+
+export const templateRegistry = new TemplatePluginRegistry();
+
+/**
+ * Register a template plugin and optionally activate it
+ *
+ * If `options` is provided it will be used to create the active renderer.
+ * If `options` is omitted but the plugin defines `defaultOptions`, the
+ * registry will activate the renderer using those defaults.
+ */
+export const registerTemplatePlugin =
+  templateRegistry.register.bind(templateRegistry);
+
+/**
+ * Gets an active template renderer by name.
+ *
+ * Returns `undefined` if the renderer is not active.
+ *
+ * @param name - Name of the renderer to retrieve
+ * @returns The active renderer, or undefined if not activated
+ *
+ * @example
+ * ```typescript
+ * import { getTemplateRenderer } from "braintrust";
+ *
+ * const renderer = getTemplateRenderer("nunjucks");
+ * if (renderer) {
+ *   const output = renderer.render(template, variables, escape, strict);
+ * }
+ * ```
+ */
+export const getTemplateRenderer = templateRegistry.get.bind(templateRegistry);
+
+// Built-in mustache plugin
+const jsonEscape = (v: unknown) =>
+  typeof v === "string" ? v : JSON.stringify(v);
+
+const mustachePlugin: TemplateRendererPlugin = {
+  name: "mustache",
+  defaultOptions: { strict: true, escape: jsonEscape },
+  createRenderer() {
+    const opts = (this.defaultOptions ?? {}) as any;
+    const escapeFn: (v: unknown) => string = opts?.escape ?? jsonEscape;
+    const strictDefault: boolean =
+      typeof opts?.strict === "boolean" ? opts.strict : true;
+
+    return {
+      render(template, variables, escape, strict) {
+        const esc = escape ?? escapeFn;
+        const strictMode = typeof strict === "boolean" ? strict : strictDefault;
+        if (strictMode) lintMustacheTemplate(template, variables);
+        return Mustache.render(template, variables, undefined, { escape: esc });
+      },
+      lint(template, variables) {
+        lintMustacheTemplate(template, variables);
+      },
+    };
+  },
+};
+
+// Auto-register built-in mustache plugin.
+registerTemplatePlugin(mustachePlugin);
diff --git a/js/src/template/renderer.ts b/js/src/template/renderer.ts
index 2d002cde7..4fc34203c 100644
--- a/js/src/template/renderer.ts
+++ b/js/src/template/renderer.ts
@@ -1,8 +1,6 @@
-import Mustache from "mustache";
-import { lintTemplate as lintMustacheTemplate } from "./mustache-utils";
-import iso from "../isomorph";
+import { getTemplateRenderer, type TemplateFormat } from "./registry";
 
-export type TemplateFormat = "mustache" | "nunjucks" | "none";
+export type { TemplateFormat } from "./registry";
 
 export function isTemplateFormat(v: unknown): v is TemplateFormat {
   return v === "mustache" || v === "nunjucks" || v === "none";
@@ -23,15 +21,22 @@ export function renderTemplateContent(
 ): string {
   const strict = !!options.strict;
   const templateFormat = parseTemplateFormat(options.templateFormat);
-  if (templateFormat === "nunjucks") {
-    return iso.renderNunjucksString(template, variables, { strict });
-  } else if (templateFormat === "mustache") {
-    if (strict) {
-      lintMustacheTemplate(template, variables);
+  if (templateFormat === "none") {
+    return template;
+  }
+
+  const renderer = getTemplateRenderer(templateFormat);
+  if (!renderer) {
+    if (templateFormat === "nunjucks") {
+      throw new Error(
+        "Nunjucks templating requires @braintrust/template-nunjucks. Install and import it to enable templateFormat: 'nunjucks'.",
+      );
     }
-    return Mustache.render(template, variables, undefined, {
-      escape,
-    });
+    throw new Error(`No template renderer registered for ${templateFormat}`);
+  }
+
+  if (strict && renderer.lint) {
+    renderer.lint(template, variables);
   }
-  return template;
+  return renderer.render(template, variables, escape, strict);
 }
diff --git a/js/tsup.config.ts b/js/tsup.config.ts
index f5100c6cb..875d4ec22 100644
--- a/js/tsup.config.ts
+++ b/js/tsup.config.ts
@@ -18,21 +18,6 @@ export default defineConfig([
     splitting: true,
     clean: true,
   },
-  {
-    entry: ["src/browser.ts"],
-    format: ["cjs", "esm"],
-    outDir: "dist",
-    removeNodeProtocol: false,
-    external: ["zod"],
-    dts: {
-      // Split DTS generation to reduce memory usage
-      compilerOptions: {
-        skipLibCheck: true,
-      },
-    },
-    splitting: true,
-    clean: false,
-  },
   {
     entry: { cli: "src/cli/index.ts" },
     format: ["cjs"],
@@ -73,4 +58,18 @@ export default defineConfig([
     splitting: true,
     clean: true,
   },
+  // Browser/edge exports - single build used by browser, edge-light, and workerd
+  {
+    entry: {
+      browser: "src/browser.ts",
+    },
+    format: ["cjs", "esm"],
+    outDir: "dist",
+    external: ["zod"],
+    removeNodeProtocol: false,
+    platform: "browser",
+    splitting: false,
+    dts: true,
+    clean: false,
+  },
 ]);
diff --git a/pnpm-lock.yaml b/pnpm-lock.yaml
index b3d52aaae..37220265d 100644
--- a/pnpm-lock.yaml
+++ b/pnpm-lock.yaml
@@ -15,6 +15,31 @@ importers:
         specifier: ^2.5.6
         version: 2.5.6
 
+  integrations/browser-js:
+    dependencies:
+      als-browser:
+        specifier: ^1.0.1
+        version: 1.0.1
+      zod:
+        specifier: ^3.25.34 || ^4.0
+        version: 3.25.76
+    devDependencies:
+      '@types/node':
+        specifier: ^20.10.5
+        version: 20.19.16
+      braintrust:
+        specifier: workspace:*
+        version: link:../../js
+      tsup:
+        specifier: ^8.3.5
+        version: 8.5.1(@swc/core@1.15.8)(jiti@2.6.1)(postcss@8.5.6)(typescript@5.5.4)(yaml@2.8.2)
+      typescript:
+        specifier: ^5.3.3
+        version: 5.5.4
+      vitest:
+        specifier: ^2.1.9
+        version: 2.1.9(@types/node@20.19.16)(msw@2.6.6(@types/node@20.19.16)(typescript@5.5.4))(terser@5.44.1)
+
   integrations/langchain-js:
     devDependencies:
       '@langchain/anthropic':
@@ -118,6 +143,31 @@ importers:
         specifier: 5.5.4
         version: 5.5.4
 
+  integrations/templates-nunjucks:
+    dependencies:
+      nunjucks:
+        specifier: ^3.2.4
+        version: 3.2.4
+    devDependencies:
+      '@types/node':
+        specifier: ^20.10.5
+        version: 20.19.16
+      '@types/nunjucks':
+        specifier: ^3.2.6
+        version: 3.2.6
+      braintrust:
+        specifier: workspace:*
+        version: link:../../js
+      tsup:
+        specifier: ^8.5.1
+        version: 8.5.1(@swc/core@1.15.8)(jiti@2.6.1)(postcss@8.5.6)(typescript@5.5.4)(yaml@2.8.2)
+      typescript:
+        specifier: 5.5.4
+        version: 5.5.4
+      vitest:
+        specifier: ^2.1.9
+        version: 2.1.9(@types/node@20.19.16)(msw@2.6.6(@types/node@20.19.16)(typescript@5.5.4))(terser@5.44.1)
+
   integrations/temporal-js:
     devDependencies:
       '@temporalio/activity':
@@ -196,9 +246,6 @@ importers:
       '@next/env':
         specifier: ^14.2.3
         version: 14.2.3
-      '@types/nunjucks':
-        specifier: ^3.2.6
-        version: 3.2.6
       '@vercel/functions':
         specifier: ^1.0.2
         version: 1.0.2
@@ -244,9 +291,6 @@ importers:
       mustache:
         specifier: ^4.2.0
         version: 4.2.0
-      nunjucks:
-        specifier: ^3.2.4
-        version: 3.2.4
       pluralize:
         specifier: ^8.0.0
         version: 8.0.0
@@ -2649,6 +2693,9 @@ packages:
   ajv@8.17.1:
     resolution: {integrity: sha512-B/gBuNg5SiMTrPkC+A2+cW0RszwxYmn6VYxB/inlBStS5nx6xHIt/ehKRhIMhqusl7a8LjQoZnjCs5vhwxOQ1g==}
 
+  als-browser@1.0.1:
+    resolution: {integrity: sha512-DjavKf6zf4DFPdEmgsEM474MBjFcZG/1amv2/+WHGf61kVQWqf7XEn4jvpjFS4ssQbh/pkmYThaPfQK1ERC+3g==}
+
   ansi-align@3.0.1:
     resolution: {integrity: sha512-IOfwwBF5iczOjp/WeY4YxyjqAFMQoZufdQWDd19SEExbVLNXqvpzSJ/M7Za4/sCPmQ0+GRquoA7bGcINcxew6w==}
 
@@ -8275,6 +8322,15 @@ snapshots:
       msw: 2.6.6(@types/node@20.19.16)(typescript@5.4.4)
       vite: 5.4.14(@types/node@20.19.16)(terser@5.44.1)
 
+  '@vitest/mocker@2.1.9(msw@2.6.6(@types/node@20.19.16)(typescript@5.5.4))(vite@5.4.14(@types/node@20.19.16)(terser@5.44.1))':
+    dependencies:
+      '@vitest/spy': 2.1.9
+      estree-walker: 3.0.3
+      magic-string: 0.30.19
+    optionalDependencies:
+      msw: 2.6.6(@types/node@20.19.16)(typescript@5.5.4)
+      vite: 5.4.14(@types/node@20.19.16)(terser@5.44.1)
+
   '@vitest/mocker@2.1.9(msw@2.6.6(@types/node@20.19.9)(typescript@5.4.4))(vite@5.4.14(@types/node@20.19.9)(terser@5.44.1))':
     dependencies:
       '@vitest/spy': 2.1.9
@@ -8555,6 +8611,8 @@ snapshots:
       json-schema-traverse: 1.0.0
       require-from-string: 2.0.2
 
+  als-browser@1.0.1: {}
+
   ansi-align@3.0.1:
     dependencies:
       string-width: 4.2.3
@@ -10831,6 +10889,32 @@ snapshots:
       - '@types/node'
     optional: true
 
+  msw@2.6.6(@types/node@20.19.16)(typescript@5.5.4):
+    dependencies:
+      '@bundled-es-modules/cookie': 2.0.1
+      '@bundled-es-modules/statuses': 1.0.1
+      '@bundled-es-modules/tough-cookie': 0.1.6
+      '@inquirer/confirm': 5.0.2(@types/node@20.19.16)
+      '@mswjs/interceptors': 0.37.3
+      '@open-draft/deferred-promise': 2.2.0
+      '@open-draft/until': 2.1.0
+      '@types/cookie': 0.6.0
+      '@types/statuses': 2.0.5
+      chalk: 4.1.2
+      graphql: 16.9.0
+      headers-polyfill: 4.0.3
+      is-node-process: 1.2.0
+      outvariant: 1.4.3
+      path-to-regexp: 6.3.0
+      strict-event-emitter: 0.5.1
+      type-fest: 4.30.0
+      yargs: 17.7.2
+    optionalDependencies:
+      typescript: 5.5.4
+    transitivePeerDependencies:
+      - '@types/node'
+    optional: true
+
   msw@2.6.6(@types/node@20.19.9)(typescript@5.4.4):
     dependencies:
       '@bundled-es-modules/cookie': 2.0.1
@@ -12468,6 +12552,41 @@ snapshots:
       - supports-color
       - terser
 
+  vitest@2.1.9(@types/node@20.19.16)(msw@2.6.6(@types/node@20.19.16)(typescript@5.5.4))(terser@5.44.1):
+    dependencies:
+      '@vitest/expect': 2.1.9
+      '@vitest/mocker': 2.1.9(msw@2.6.6(@types/node@20.19.16)(typescript@5.5.4))(vite@5.4.14(@types/node@20.19.16)(terser@5.44.1))
+      '@vitest/pretty-format': 2.1.9
+      '@vitest/runner': 2.1.9
+      '@vitest/snapshot': 2.1.9
+      '@vitest/spy': 2.1.9
+      '@vitest/utils': 2.1.9
+      chai: 5.2.0
+      debug: 4.4.3
+      expect-type: 1.2.0
+      magic-string: 0.30.19
+      pathe: 1.1.2
+      std-env: 3.8.1
+      tinybench: 2.9.0
+      tinyexec: 0.3.2
+      tinypool: 1.0.2
+      tinyrainbow: 1.2.0
+      vite: 5.4.14(@types/node@20.19.16)(terser@5.44.1)
+      vite-node: 2.1.9(@types/node@20.19.16)(terser@5.44.1)
+      why-is-node-running: 2.3.0
+    optionalDependencies:
+      '@types/node': 20.19.16
+    transitivePeerDependencies:
+      - less
+      - lightningcss
+      - msw
+      - sass
+      - sass-embedded
+      - stylus
+      - sugarss
+      - supports-color
+      - terser
+
   vitest@2.1.9(@types/node@20.19.9)(msw@2.6.6(@types/node@20.19.9)(typescript@5.4.4))(terser@5.44.1):
     dependencies:
       '@vitest/expect': 2.1.9