Interactive visualization of the midpoint + 6h sleep-grouping rule

.github/workflows/pages.yml

@@ -0,0 +1,40 @@
+name: Deploy interactive viz to GitHub Pages
+
+on:
+  push:
+    branches: [master]
+    paths:
+      - "docs/**"
+      - ".github/workflows/pages.yml"
+  workflow_dispatch:
+
+permissions:
+  contents: read
+  pages: write
+  id-token: write
+
+concurrency:
+  group: pages
+  cancel-in-progress: true
+
+jobs:
+  deploy:
+    environment:
+      name: github-pages
+      url: ${{ steps.deployment.outputs.page_url }}
+    runs-on: ubuntu-latest
+    steps:
+      - name: Checkout
+        uses: actions/checkout@v4
+
+      - name: Configure Pages
+        uses: actions/configure-pages@v5
+
+      - name: Upload artifact
+        uses: actions/upload-pages-artifact@v3
+        with:
+          path: docs
+
+      - name: Deploy to GitHub Pages
+        id: deployment
+        uses: actions/deploy-pages@v4

README.md

@@ -44,6 +44,13 @@ A native iOS app that helps optimize your sleep by tracking your "sleep bank" an
 3. Grant HealthKit permissions when prompted
 4. Configure your sleep goal and wake time in settings
 
+## Interactive: Midpoint + 6h grouping
+
+Sleep sessions are assigned to a calendar day using a "midpoint + 6 hours" rule (see
+`SleepSession.dateForGrouping`). An interactive visualization of this rule lives in
+[`docs/index.html`](docs/index.html) and is published via GitHub Pages (enable Pages →
+"GitHub Actions" in repo settings to host it).
+
 ## Privacy
 
 - All data stays on your device