diff --git a/browser-extension/README.md b/browser-extension/README.md
index 9df13d5..ca426bc 100644
--- a/browser-extension/README.md
+++ b/browser-extension/README.md
@@ -31,7 +31,7 @@ Start a Deep Sesh or Pomodoro session before testing browser activity.
 3. Click Load unpacked.
 4. Select the project `browser-extension` folder.
 5. Start a Taskmaster focus session, then switch tabs.
-6. Native Messaging requires a host install step that will be added in the next phase.
+6. Install the native host using the steps below.
 
 ## Load In Opera GX
 
@@ -50,9 +50,24 @@ Start a Deep Sesh or Pomodoro session before testing browser activity.
 5. Stop the Taskmaster session.
 6. Switch browser tabs again and confirm the panel no longer receives new activity.
 
+## Install Native Messaging Host
+
+From the project root:
+
+```powershell
+.\native-host\install-chrome-native-host.ps1
+```
+
+This registers the host under the current Windows user:
+
+```txt
+HKCU\Software\Google\Chrome\NativeMessagingHosts\com.taskmaster.browser_monitor
+```
+
+Restart Chrome after installing the host.
+
 ## Current Limitations
 
-- Native Messaging host setup is not implemented yet.
 - It only reports the active tab in the focused browser window.
 - It does not classify, block, notify, or persist browsing activity.
 - Internal browser pages such as `chrome://`, `edge://`, `opera://`, `about:`, and `devtools://` are ignored.
@@ -76,6 +91,12 @@ The package includes only:
 - `manifest.json`
 - `background.js`
 
-## Future Production Plan
+## Native Messaging
+
+The extension uses:
+
+```txt
+com.taskmaster.browser_monitor
+```
 
-The next phase will add the Native Messaging host and install scripts.
+The native host forwards validated messages to the local Taskmaster desktop app on the same device.
diff --git a/browser-extension/background.js b/browser-extension/background.js
index 5975ddc..9bceaf8 100644
--- a/browser-extension/background.js
+++ b/browser-extension/background.js
@@ -7,8 +7,8 @@
 // - Page content, cookies, form inputs, and the browsing history API are never read.
 // - The active tab URL/title is queried only after Taskmaster says monitoring is active.
 //
-// Transport is intentionally separated from tab collection so the same privacy
-// gate can work with the current dev localhost bridge and future Native Messaging.
+// Transport is intentionally separated from tab collection. Production uses
+// Native Messaging; the old localhost path is retained only for local debugging.
 
 const BRIDGE_ORIGIN = 'http://127.0.0.1:17382'
 const STATUS_URL = `${BRIDGE_ORIGIN}/taskmaster-browser-monitor/status`
@@ -91,7 +91,8 @@ async function isMonitoringEnabled() {
   return isDevLocalhostMonitoringEnabled()
 }
 
-// Placeholder production status check. Phase 2 will wire this to the native host.
+// Production status check. Chrome launches the registered Native Messaging host,
+// then the host asks the local Taskmaster bridge whether monitoring is active.
 async function isNativeMonitoringEnabled() {
   try {
     const response = await chrome.runtime.sendNativeMessage(NATIVE_HOST_NAME, {
@@ -156,7 +157,7 @@ async function sendActivity(payload) {
   await sendDevLocalhostActivity(payload)
 }
 
-// Placeholder production sender. Phase 2 will add the native host implementation.
+// Production sender. The native host validates and forwards this to Taskmaster.
 async function sendNativeActivity(payload) {
   try {
     await chrome.runtime.sendNativeMessage(NATIVE_HOST_NAME, {
diff --git a/electron/src/main/browser-activity-bridge.ts b/electron/src/main/browser-activity-bridge.ts
index 3a875d0..33315c4 100644
--- a/electron/src/main/browser-activity-bridge.ts
+++ b/electron/src/main/browser-activity-bridge.ts
@@ -1,5 +1,6 @@
-// Dev-only localhost bridge for the Taskmaster browser extension prototype.
-// This accepts active tab metadata only while a focus session has enabled monitoring.
+// Local Taskmaster app bridge for browser activity messages.
+// Native Messaging host forwards validated active-tab metadata here while a
+// focus session has enabled monitoring.
 
 import http from 'node:http'
 import type { BrowserActivityPayload } from '../shared/browserActivity.ts'
@@ -16,7 +17,7 @@ let isBrowserMonitoringActive = false
 let latestBrowserActivity: BrowserActivityPayload | null = null
 let notifyRenderer: BrowserActivityListener | null = null
 
-/* Starts the dev HTTP bridge once the Electron app is ready. */
+/* Starts the local HTTP bridge once the Electron app is ready. */
 export function startBrowserActivityBridge(onActivity: BrowserActivityListener) {
   notifyRenderer = onActivity
 
@@ -57,7 +58,7 @@ export function startBrowserActivityBridge(onActivity: BrowserActivityListener)
   })
 }
 
-/* Closes the local bridge during app shutdown. */
+/* Closes the local app bridge during app shutdown. */
 export function stopBrowserActivityBridge() {
   setBrowserMonitoringActive(false)
 
@@ -186,7 +187,7 @@ function isRecord(value: unknown): value is Record<string, unknown> {
   return typeof value === 'object' && value !== null
 }
 
-/* Allows the unpacked dev extension to call the local bridge during development. */
+/* Allows local development and the native host to call the app bridge. */
 function addCorsHeaders(response: http.ServerResponse) {
   response.setHeader('Access-Control-Allow-Origin', '*')
   response.setHeader('Access-Control-Allow-Methods', 'GET,POST,OPTIONS')
diff --git a/native-host/.gitignore b/native-host/.gitignore
new file mode 100644
index 0000000..1d7ebf0
--- /dev/null
+++ b/native-host/.gitignore
@@ -0,0 +1,2 @@
+# Ignore machine-specific launchers/manifests generated by the native host installer.
+.generated/
diff --git a/native-host/README.md b/native-host/README.md
new file mode 100644
index 0000000..6082760
--- /dev/null
+++ b/native-host/README.md
@@ -0,0 +1,69 @@
+# Taskmaster Browser Monitor Native Host
+
+This folder contains the Chrome Native Messaging host for the Taskmaster Browser Monitor extension.
+
+The extension talks to this host through Chrome Native Messaging. The host then forwards validated messages to the local Taskmaster desktop app bridge on `127.0.0.1:17382`.
+
+The extension itself does not require localhost host permissions.
+
+## Host Name
+
+```txt
+com.taskmaster.browser_monitor
+```
+
+## Allowed Chrome Extension
+
+```txt
+kibldolnfbpajohdnkbjfjefnemllapm
+```
+
+## Install On Windows
+
+From the repo root:
+
+```powershell
+.\native-host\install-chrome-native-host.ps1
+```
+
+This registers the host under:
+
+```txt
+HKCU\Software\Google\Chrome\NativeMessagingHosts\com.taskmaster.browser_monitor
+```
+
+HKCU is used so admin rights are not required.
+
+## Verify Registration
+
+1. Open `regedit`.
+2. Go to:
+   ```txt
+   HKEY_CURRENT_USER\Software\Google\Chrome\NativeMessagingHosts\com.taskmaster.browser_monitor
+   ```
+3. Confirm the default value points to the generated manifest in:
+   ```txt
+   native-host\.generated\com.taskmaster.browser_monitor.chrome.json
+   ```
+
+## Test Flow
+
+1. Install the native host.
+2. Start Taskmaster Electron dev.
+3. Load or install the Chrome extension with ID `kibldolnfbpajohdnkbjfjefnemllapm`.
+4. Start a Deep Sesh or Pomodoro session.
+5. Open GitHub, YouTube, or ChatGPT.
+6. Confirm FocusMonitorPanel shows the current domain and title.
+7. Stop the focus session and confirm tab updates stop.
+
+## Debugging
+
+If Chrome says the native host was not found:
+
+- Confirm the registry key exists under HKCU, not HKLM.
+- Confirm the manifest path in the registry exists.
+- Confirm the generated manifest `path` points to the generated `.cmd` launcher.
+- Confirm `node` is installed and available when running the install script.
+- Restart Chrome after installing the native host.
+
+Raw URLs are not logged by default.
diff --git a/native-host/com.taskmaster.browser_monitor.chrome.json b/native-host/com.taskmaster.browser_monitor.chrome.json
new file mode 100644
index 0000000..17c226e
--- /dev/null
+++ b/native-host/com.taskmaster.browser_monitor.chrome.json
@@ -0,0 +1,9 @@
+{
+  "name": "com.taskmaster.browser_monitor",
+  "description": "Taskmaster Browser Monitor Native Host",
+  "path": "ABSOLUTE_PATH_CREATED_BY_install-chrome-native-host.ps1",
+  "type": "stdio",
+  "allowed_origins": [
+    "chrome-extension://kibldolnfbpajohdnkbjfjefnemllapm/"
+  ]
+}
diff --git a/native-host/install-chrome-native-host.ps1 b/native-host/install-chrome-native-host.ps1
new file mode 100644
index 0000000..178ca15
--- /dev/null
+++ b/native-host/install-chrome-native-host.ps1
@@ -0,0 +1,41 @@
+# Registers the Taskmaster Browser Monitor native host for Chrome under HKCU.
+# This does not require admin rights and writes a generated local manifest.
+
+$ErrorActionPreference = "Stop"
+
+$hostName = "com.taskmaster.browser_monitor"
+$nativeHostDir = $PSScriptRoot
+$generatedDir = Join-Path $nativeHostDir ".generated"
+$generatedManifestPath = Join-Path $generatedDir "$hostName.chrome.json"
+$generatedLauncherPath = Join-Path $generatedDir "taskmaster-browser-monitor-host.cmd"
+$hostScriptPath = Join-Path $nativeHostDir "taskmaster-browser-monitor-host.js"
+$nodePath = (Get-Command node -ErrorAction Stop).Source
+$registryPath = "HKCU:\Software\Google\Chrome\NativeMessagingHosts\$hostName"
+
+New-Item -ItemType Directory -Path $generatedDir -Force | Out-Null
+
+$launcherContent = @"
+@echo off
+"$nodePath" "$hostScriptPath"
+"@
+
+Set-Content -LiteralPath $generatedLauncherPath -Value $launcherContent -Encoding ASCII
+
+$manifest = @{
+  name = $hostName
+  description = "Taskmaster Browser Monitor Native Host"
+  path = $generatedLauncherPath
+  type = "stdio"
+  allowed_origins = @(
+    "chrome-extension://kibldolnfbpajohdnkbjfjefnemllapm/"
+  )
+}
+
+$manifest | ConvertTo-Json -Depth 4 | Set-Content -LiteralPath $generatedManifestPath -Encoding UTF8
+
+New-Item -Path $registryPath -Force | Out-Null
+Set-Item -Path $registryPath -Value $generatedManifestPath
+
+Write-Host "Registered $hostName"
+Write-Host "Manifest: $generatedManifestPath"
+Write-Host "Registry: $registryPath"
diff --git a/native-host/taskmaster-browser-monitor-host.js b/native-host/taskmaster-browser-monitor-host.js
new file mode 100644
index 0000000..f5a4e78
--- /dev/null
+++ b/native-host/taskmaster-browser-monitor-host.js
@@ -0,0 +1,201 @@
+#!/usr/bin/env node
+// Native Messaging host for Taskmaster Browser Monitor.
+// Reads Chrome length-prefixed JSON from stdin, validates messages, and forwards
+// active-tab metadata to the local Taskmaster desktop app bridge.
+
+const http = require('node:http')
+
+const BRIDGE_HOST = '127.0.0.1'
+const BRIDGE_PORT = 17382
+const STATUS_PATH = '/taskmaster-browser-monitor/status'
+const ACTIVITY_PATH = '/taskmaster-browser-monitor/activity'
+const MAX_MESSAGE_BYTES = 1024 * 1024
+
+let inputBuffer = Buffer.alloc(0)
+
+process.stdin.on('data', (chunk) => {
+  inputBuffer = Buffer.concat([inputBuffer, chunk])
+  readAvailableMessages()
+})
+
+process.stdin.on('end', () => {
+  process.exit(0)
+})
+
+process.stdin.resume()
+
+function readAvailableMessages() {
+  while (inputBuffer.length >= 4) {
+    const messageLength = inputBuffer.readUInt32LE(0)
+
+    if (messageLength > MAX_MESSAGE_BYTES) {
+      writeNativeResponse({ ok: false, error: 'Message too large' })
+      process.exit(1)
+    }
+
+    if (inputBuffer.length < messageLength + 4) {
+      return
+    }
+
+    const messageBuffer = inputBuffer.subarray(4, messageLength + 4)
+    inputBuffer = inputBuffer.subarray(messageLength + 4)
+
+    void handleNativeMessage(messageBuffer)
+  }
+}
+
+async function handleNativeMessage(messageBuffer) {
+  let message
+
+  try {
+    message = JSON.parse(messageBuffer.toString('utf8'))
+  } catch {
+    writeNativeResponse({ ok: false, error: 'Invalid JSON' })
+    return
+  }
+
+  if (!isRecord(message) || typeof message.type !== 'string') {
+    writeNativeResponse({ ok: false, error: 'Invalid message shape' })
+    return
+  }
+
+  if (message.type === 'taskmaster-browser-monitor-status') {
+    await handleStatusMessage()
+    return
+  }
+
+  if (message.type === 'taskmaster-browser-activity') {
+    await handleActivityMessage(message.payload)
+    return
+  }
+
+  writeNativeResponse({ ok: false, error: 'Unknown message type' })
+}
+
+async function handleStatusMessage() {
+  try {
+    const status = await requestTaskmaster({
+      method: 'GET',
+      path: STATUS_PATH,
+    })
+
+    writeNativeResponse({
+      ok: true,
+      enabled: status.enabled === true,
+    })
+  } catch {
+    writeNativeResponse({
+      ok: false,
+      enabled: false,
+      error: 'Taskmaster bridge unavailable',
+    })
+  }
+}
+
+async function handleActivityMessage(payload) {
+  const validatedPayload = parseBrowserActivityPayload(payload)
+
+  if (!validatedPayload) {
+    writeNativeResponse({ ok: false, error: 'Invalid activity payload' })
+    return
+  }
+
+  try {
+    const response = await requestTaskmaster({
+      method: 'POST',
+      path: ACTIVITY_PATH,
+      body: validatedPayload,
+    })
+
+    writeNativeResponse({
+      ok: true,
+      accepted: response.accepted === true,
+    })
+  } catch {
+    writeNativeResponse({
+      ok: false,
+      accepted: false,
+      error: 'Taskmaster bridge unavailable',
+    })
+  }
+}
+
+function requestTaskmaster({ method, path, body }) {
+  const requestBody = body ? JSON.stringify(body) : ''
+
+  return new Promise((resolve, reject) => {
+    const request = http.request(
+      {
+        host: BRIDGE_HOST,
+        port: BRIDGE_PORT,
+        path,
+        method,
+        headers: {
+          'Content-Type': 'application/json',
+          'Content-Length': Buffer.byteLength(requestBody),
+        },
+      },
+      (response) => {
+        const chunks = []
+
+        response.on('data', (chunk) => chunks.push(chunk))
+        response.on('end', () => {
+          const rawBody = Buffer.concat(chunks).toString('utf8')
+
+          if (!response.statusCode || response.statusCode >= 400) {
+            reject(new Error(`Taskmaster returned ${response.statusCode}`))
+            return
+          }
+
+          try {
+            resolve(rawBody ? JSON.parse(rawBody) : {})
+          } catch {
+            reject(new Error('Taskmaster returned invalid JSON'))
+          }
+        })
+      }
+    )
+
+    request.on('error', reject)
+    request.write(requestBody)
+    request.end()
+  })
+}
+
+function parseBrowserActivityPayload(value) {
+  if (!isRecord(value)) {
+    return null
+  }
+
+  if (
+    value.source !== 'taskmaster-browser-extension' ||
+    value.browser !== 'chromium' ||
+    typeof value.title !== 'string' ||
+    typeof value.url !== 'string' ||
+    typeof value.domain !== 'string' ||
+    typeof value.timestamp !== 'number'
+  ) {
+    return null
+  }
+
+  return {
+    source: 'taskmaster-browser-extension',
+    title: value.title.slice(0, 500),
+    url: value.url.slice(0, 2048),
+    domain: value.domain.slice(0, 255),
+    browser: 'chromium',
+    timestamp: value.timestamp,
+  }
+}
+
+function writeNativeResponse(message) {
+  const response = Buffer.from(JSON.stringify(message), 'utf8')
+  const header = Buffer.alloc(4)
+
+  header.writeUInt32LE(response.length, 0)
+  process.stdout.write(Buffer.concat([header, response]))
+}
+
+function isRecord(value) {
+  return typeof value === 'object' && value !== null
+}
diff --git a/native-host/uninstall-chrome-native-host.ps1 b/native-host/uninstall-chrome-native-host.ps1
new file mode 100644
index 0000000..81b9b98
--- /dev/null
+++ b/native-host/uninstall-chrome-native-host.ps1
@@ -0,0 +1,14 @@
+# Unregisters the Taskmaster Browser Monitor native host from Chrome under HKCU.
+# Generated files are left on disk so local debugging artifacts are not removed unexpectedly.
+
+$ErrorActionPreference = "Stop"
+
+$hostName = "com.taskmaster.browser_monitor"
+$registryPath = "HKCU:\Software\Google\Chrome\NativeMessagingHosts\$hostName"
+
+if (Test-Path $registryPath) {
+  Remove-Item -LiteralPath $registryPath -Recurse -Force
+  Write-Host "Unregistered $hostName"
+} else {
+  Write-Host "$hostName was not registered"
+}