abdulsaheel · Nov 1, 2026 · Oct 15, 2026 · Oct 15, 2026 · Oct 15, 2026 · Oct 15, 2026
diff --git a/AGENTS.md b/AGENTS.md
@@ -16,7 +16,8 @@ symbol names don't; verify against the source, not this doc.
 A Flutter health app for wearables (WHOOP 4.0/5.0/MG supported today). **Fully on-device,
 local-first**: BLE offload → SQLite → on-device analytics → UI. No backend owns
 user data. Network use is limited to OTA update pointers, opt-in
-telemetry/Crashlytics, and BYOK LLM calls.
+telemetry/Crashlytics, and BYOK LLM calls (or the user's ChatGPT sign-in,
+whose OAuth calls go to auth.openai.com).
 
 Three sibling repos, strict separation — push work to the right one:
 - `OpenStrap/protocol` — bytes: GATT, framing, CRC, opcodes, record decode.

diff --git a/PRIVACY.md b/PRIVACY.md
@@ -161,7 +161,11 @@ configure:
 - **AI Coach** — if you enable this feature and supply your own API key,
   summaries of your data are sent to the AI provider you configure (by
   default, OpenAI) to generate coaching responses. Off by default and
-  requires your own API key.
+  requires your own API key, or signing in with ChatGPT (Plus or Pro), in
+  which case the same data goes to OpenAI under your ChatGPT account and your
+  ChatGPT data controls, including model-training settings, may apply to it.
+  Check them in ChatGPT settings. The sign-in tokens are kept in the device
+  keychain/keystore and sent only to OpenAI.
 - **Health app integration** — if you enable it, the App can write derived
   daily metrics to Apple Health or Google Health Connect, which are controlled
   by your device's own OS-level health app, not by us. The App can also *read*

diff --git a/android/app/src/main/AndroidManifest.xml b/android/app/src/main/AndroidManifest.xml
@@ -344,5 +344,11 @@
         </intent>
         <!-- Health Connect app discovery (for install/status checks). -->
         <package android:name="com.google.android.apps.healthdata" />
+        <!-- Lets url_launcher find a Custom Tabs browser for the "Sign in with
+             ChatGPT" page (LaunchMode.inAppBrowserView); without it Android 11+
+             falls back to a WebView. -->
+        <intent>
+            <action android:name="android.support.customtabs.action.CustomTabsService" />
+        </intent>
     </queries>
 </manifest>
diff --git a/guides/AI_COACH.md b/guides/AI_COACH.md
@@ -1,9 +1,11 @@
-# AI Coach — bring your own key
+# AI Coach — your own model, or your ChatGPT plan
 
 The AI features in OpenStrap Edge (the Coach chat, the morning and evening
 briefings, and the pre-sleep journal) are all powered by a model **you**
-provide. There's no OpenStrap AI service: you paste in an API key for any
-OpenAI-compatible provider and the app talks to that provider directly.
+provide. There's no OpenStrap AI service. There are two ways to set it up:
+paste in an API key for any OpenAI-compatible provider, or
+[sign in with your ChatGPT plan](#use-your-chatgpt-plan). Either way the app
+talks to that provider directly.
 
 Your key is stored in the device keychain/keystore and is only ever sent to
 the base URL you configure — never to OpenStrap.
@@ -14,7 +16,37 @@ the provider you configure. Before enabling the feature, check that
 provider's data retention and training policies — or point the app at a
 model you host yourself.
 
-## Setup
+## Use your ChatGPT plan
+
+If you pay for ChatGPT Plus or Pro, you can skip the API key: open
+**AI Coach → settings**, tap **ChatGPT** and sign in. Eligible coach, briefing and journal requests then use
+the usage included in your ChatGPT plan instead of API billing. Tap **List
+models** and pick one, then **Save**.
+
+Before the sign-in starts, the app links OpenAI's
+[Terms of Use](https://openai.com/policies/terms-of-use/) and
+[Usage Policies](https://openai.com/policies/usage-policies/). They apply to
+your use of ChatGPT here, so read them before you continue.
+
+- This uses OpenAI's official
+  [Sign in with ChatGPT](https://developers.openai.com/siwc/token-sharing-open-source)
+  for open-source apps. OpenStrap never sees your password, and never charges
+  for it.
+- Set a limit, or disconnect OpenStrap, under
+  [ChatGPT settings → Usage](https://chatgpt.com/settings/usage). The
+  **Manage usage** button in AI settings goes there.
+- When the limit is reached the coach says so and stops; it never quietly
+  switches to an API key.
+- Your questions and the rows the coach reads go to OpenAI under your ChatGPT
+  account. Your ChatGPT data controls, including whether your content may be
+  used to train models, may apply to these requests, and they are not the same
+  terms as an OpenAI API key. Check them in ChatGPT settings before using this.
+- **Sign out of ChatGPT** asks OpenAI to revoke the sign-in and clears it from
+  the phone. If the app says revocation wasn't confirmed, also disconnect
+  OpenStrap in ChatGPT settings. The coach then stays off until you sign in
+  again or pick another provider.
+
+## Setup with an API key
 
 <img src="images/ai-coach/settings.png" width="300" align="right">