Add the WebBrain for websites widget as embed/

.github/workflows/embed.yml

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+name: Embed widget
+
+# Builds and tests the WebBrain for websites widget (embed/) whenever it or
+# the extension code it bundles changes, including loading embed.js in Chrome.
+# Pushing a tag like embed-v1.0.0 publishes a GitHub release with embed.js,
+# tools.json, the icons, VERSION.json and SHA256SUMS, which sites.webbrain.one
+# pins by version.
+
+on:
+  pull_request:
+    paths:
+      - ".github/workflows/embed.yml"
+      - "embed/**"
+      - "package.json"
+      - "package-lock.json"
+      - "src/chrome/**"
+  push:
+    branches:
+      - main
+    paths:
+      - ".github/workflows/embed.yml"
+      - "embed/**"
+      - "package.json"
+      - "package-lock.json"
+      - "src/chrome/**"
+    tags:
+      - "embed-v*"
+
+permissions:
+  contents: read
+
+concurrency:
+  group: embed-${{ github.ref }}
+  cancel-in-progress: true
+
+jobs:
+  test:
+    runs-on: ubuntu-24.04
+    timeout-minutes: 10
+    defaults:
+      run:
+        working-directory: embed
+    steps:
+      - uses: actions/checkout@v4
+
+      - uses: actions/setup-node@v4
+        with:
+          node-version: 22
+          cache: npm
+
+      - name: Build and test
+        run: |
+          npm run build
+          npm test
+
+      # Playwright comes from the repository root; the widget itself has no dependencies.
+      - name: Install Playwright
+        working-directory: .
+        run: npm ci
+
+      - name: Run embed.js in Chrome
+        env:
+          EMBED_CHROME_PATH: /usr/bin/google-chrome
+        run: npm run test:browser
+
+  release:
+    if: startsWith(github.ref, 'refs/tags/embed-v')
+    needs: test
+    runs-on: ubuntu-24.04
+    timeout-minutes: 5
+    permissions:
+      contents: write
+    defaults:
+      run:
+        working-directory: embed
+    steps:
+      - uses: actions/checkout@v4
+
+      - uses: actions/setup-node@v4
+        with:
+          node-version: 22
+
+      - name: Check the tag matches embed/package.json
+        run: |
+          version="$(node -p "require('./package.json').version")"
+          if [ "${GITHUB_REF_NAME}" != "embed-v${version}" ]; then
+            echo "Tag ${GITHUB_REF_NAME} does not match embed/package.json version ${version}" >&2
+            exit 1
+          fi
+
+      - name: Build
+        run: npm run build
+
+      - name: Publish the release
+        env:
+          GH_TOKEN: ${{ github.token }}
+        run: |
+          gh release create "${GITHUB_REF_NAME}" dist/* \
+            --title "WebBrain for websites widget ${GITHUB_REF_NAME#embed-v}" \
+            --notes "The script site owners add with <script src=\".../embed.js\">, built from commit ${GITHUB_SHA}. Verify downloads against SHA256SUMS. Source: https://github.com/${GITHUB_REPOSITORY}/tree/${GITHUB_SHA}/embed" \
+            --latest=false

embed/.gitignore

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+dist/

embed/README.md

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+# WebBrain for websites — the embed widget
+
+The script a site owner adds to their pages to give every visitor a WebBrain
+assistant:
+
+```html
+<script src="https://sites.webbrain.one/embed.js" data-site-id="site_…"></script>
+```
+
+It is built from the WebBrain extension's own code in this repository, so the
+widget reads and acts on pages exactly the way the extension does:
+
+| Extension file (`src/chrome/`) | What the widget uses it for |
+| --- | --- |
+| `src/content/accessibility-tree.js` | Reading the page as an accessibility tree |
+| `src/content/content.js` | Clicking, typing, scrolling and extracting on the page |
+| `src/content/agent-visual-indicator.js` | The on-page activity glow |
+| `src/ui/activity-brain.js` | The thinking animation |
+| `src/ui/markdown-render.js` | Rendering answers |
+| `src/agent/calculator.js` | Exact arithmetic |
+| `src/agent/read-page-window.js` | Paging `read_page` results |
+| `src/agent/credential-fields.js` | Keeping credential field values out of tool results |
+| `src/agent/tools.js`, `adapters.js` | The Ask and Act tools and prompts in `tools.json` |
+
+`src/widget-runtime.js` adds the launcher, the chat panel and the agent loop
+that talks to the server. The widget only runs the tools `tools.json` lists
+for the turn's mode, and Act is off unless the site's config sets
+`modePolicy: "ask_and_act"`.
+
+Elements with `data-webbrain-ask="…"` start an Ask run when a visitor clicks
+them. `data-webbrain-act="…"` only puts its prompt in the composer for the
+visitor to send, since any markup on the page, including content the site's
+users wrote, can carry the attribute.
+
+The widget is licensed GPL-3.0-or-later, like the rest of WebBrain. Every copy
+of `embed.js` states its license and links back to this folder.
+
+## Build and test
+
+No dependencies to install; Node 20 or newer.
+
+```bash
+cd embed
+npm run build   # writes dist/
+npm test
+npm run test:browser   # loads embed.js in Chrome; needs `npm ci` at the repository root
+```
+
+`dist/` contains:
+
+| File | Purpose |
+| --- | --- |
+| `embed.js` | The widget |
+| `tools.json` | System prompts and tool definitions for the server that answers the widget |
+| `icon48.png`, `icon128.png` | WebBrain icons the widget shows |
+| `VERSION.json` | Widget version, the commit it was built from, and a link to that source |
+| `SHA256SUMS` | Checksums of the files above |
+
+## Releases
+
+1. Bump `version` in `embed/package.json`.
+2. Push a tag `embed-v<version>`, for example `embed-v1.0.0`.
+
+The **Embed widget** workflow builds, tests and publishes a GitHub release
+with the files above. It is never marked as the repository's latest release,
+so extension releases stay on top.
+
+The server behind sites.webbrain.one pins one of these releases by version and
+checks it against `SHA256SUMS`. Pull requests that change the widget or the
+extension files it bundles run the same build and tests.

embed/package.json

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+{
+  "name": "@webbrain/embed",
+  "version": "1.0.0",
+  "private": true,
+  "description": "WebBrain for websites: the script site owners add to their pages. Built from the WebBrain extension's own content scripts.",
+  "type": "module",
+  "license": "GPL-3.0-or-later",
+  "scripts": {
+    "build": "node scripts/build.mjs",
+    "test": "node --no-warnings --test test/*.test.mjs",
+    "test:browser": "node --no-warnings --test test/browser.mjs"
+  },
+  "repository": {
+    "type": "git",
+    "url": "https://github.com/webbrain-one/webbrain.git",
+    "directory": "embed"
+  }
+}

embed/scripts/build.mjs

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+#!/usr/bin/env node
+/**
+ * Builds the WebBrain for websites widget into embed/dist/:
+ *
+ *   embed.js      the script site owners add with <script src=".../embed.js">
+ *   tools.json    prompts and tool definitions for the server that answers it
+ *   icon48.png, icon128.png
+ *   VERSION.json  widget version and the WebBrain commit it was built from
+ *   SHA256SUMS    checksums of the files above, for servers that pin a release
+ *
+ * The bundle is assembled from the extension's own code in src/chrome, so a
+ * change there reaches the widget on the next build.
+ */
+import crypto from 'node:crypto';
+import fs from 'node:fs';
+import path from 'node:path';
+import vm from 'node:vm';
+import { execFileSync } from 'node:child_process';
+import { PROJECT_ROOT, REPO_ROOT, EXTENSION_PATHS } from '../src/webbrain.js';
+import { buildEmbedBundle } from '../src/bundle.js';
+import { buildAgentSpec } from '../src/agent-spec.js';
+
+const distDir = path.resolve(PROJECT_ROOT, 'dist');
+fs.rmSync(distDir, { recursive: true, force: true });
+fs.mkdirSync(distDir, { recursive: true });
+
+const write = (name, contents) => fs.writeFileSync(path.join(distDir, name), contents);
+
+const bundle = buildEmbedBundle();
+// Parse with the grammar of a classic <script>, the way sites load embed.js.
+// (`node --check` would parse it as an ES module, since this package is "type": "module".)
+new vm.Script(bundle, { filename: 'embed.js' });
+write('embed.js', bundle);
+
+write('tools.json', `${JSON.stringify(buildAgentSpec(), null, 2)}\n`);
+fs.copyFileSync(EXTENSION_PATHS.icon48, path.join(distDir, 'icon48.png'));
+fs.copyFileSync(EXTENSION_PATHS.icon128, path.join(distDir, 'icon128.png'));
+
+const pkg = JSON.parse(fs.readFileSync(path.resolve(PROJECT_ROOT, 'package.json'), 'utf8'));
+let commit = process.env.GITHUB_SHA || '';
+if (!commit) {
+  try {
+    commit = execFileSync('git', ['-C', REPO_ROOT, 'rev-parse', 'HEAD'], { encoding: 'utf8', stdio: ['ignore', 'pipe', 'ignore'] }).trim();
+  } catch {
+    commit = 'unknown';
+  }
+}
+write('VERSION.json', `${JSON.stringify({
+  name: pkg.name,
+  version: pkg.version,
+  commit,
+  source: `https://github.com/webbrain-one/webbrain/tree/${commit === 'unknown' ? 'main' : commit}/embed`,
+  license: pkg.license,
+}, null, 2)}\n`);
+
+const files = ['embed.js', 'tools.json', 'icon48.png', 'icon128.png', 'VERSION.json'];
+const sums = files.map((name) => {
+  const hash = crypto.createHash('sha256').update(fs.readFileSync(path.join(distDir, name))).digest('hex');
+  return `${hash}  ${name}`;
+});
+write('SHA256SUMS', `${sums.join('\n')}\n`);
+
+console.log(`✓ Built embed/dist/embed.js (${(Buffer.byteLength(bundle) / 1024).toFixed(1)} KB), tools.json, icons, VERSION.json and SHA256SUMS`);

embed/src/agent-spec.js

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+import {
+  getEmbedToolsForMode,
+  SYSTEM_PROMPT_ASK,
+  SYSTEM_PROMPT_ACT_COMPACT,
+  UNIVERSAL_PREAMBLE,
+} from './webbrain.js';
+
+/**
+ * The agent specification a server needs to drive the widget: the system
+ * prompts and the tool definitions for Ask and Act mode, taken from the
+ * extension so both always agree. Published as `tools.json` with each release.
+ */
+export function buildAgentSpec() {
+  const ask = getEmbedToolsForMode('ask');
+  const act = getEmbedToolsForMode('act');
+  return {
+    version: 1,
+    prompts: {
+      ask: SYSTEM_PROMPT_ASK,
+      act: SYSTEM_PROMPT_ACT_COMPACT,
+      universalPreamble: UNIVERSAL_PREAMBLE,
+    },
+    tools: { ask, act },
+    askToolNames: ask.map((tool) => tool.function.name),
+    actToolNames: act.map((tool) => tool.function.name),
+  };
+}