docs: Add pull request guidelines with user-facing changelog conventions

.claude/CLAUDE.md

@@ -44,5 +44,6 @@ Detailed guidelines are in `.claude/rules/`:
 - `build-commands.md` — Build, test, lint, and release commands
 - `localization.md` — String resource naming conventions
 - `commit-guidelines.md` — Commit message format and prefixes
+- `pull-requests.md` — PR title and description conventions
 - `agent-instructions.md` — Sub-agent delegation and critical thinking
 - `screenshots.md` — Play Store screenshot pipeline, commands, adding new screens

.claude/rules/pull-requests.md

@@ -0,0 +1,80 @@
+---
+description: Pull request naming and description conventions
+globs:
+  - "**"
+---
+
+# Pull Request Guidelines
+
+## PR Title Format
+
+```
+<Category>: <Short user-facing summary>
+```
+
+PR titles appear in auto-generated changelogs and are read by users. Use **ELI5, user-facing language** — no internal class names, library names, or implementation details.
+
+## Category Prefixes
+
+| Prefix | Covers |
+|--------|--------|
+| **Widget** | Home screen widget |
+| **Reaction** | Case-open popup, auto-play/pause, notification triggers |
+| **Device** | AirPods detection, compatibility, Bluetooth scanning, battery reading, device profiles |
+| **General** | Dashboard, settings, notifications, themes, onboarding, support, app-wide UI |
+| **Fix** | Bug fixes spanning multiple areas |
+
+For non-user-facing PRs (refactors, tests, CI, dependency bumps, translations), apply the `changelog-ignore` GitHub label. These don't need user-facing titles.
+
+### Title Examples
+
+- `Widget: Add color themes and transparency slider`
+- `Reaction: Fix popup appearing twice when opening AirPods case`
+- `Device: Add support for AirPods 4 with ANC`
+- `General: Add dark mode and color theme settings`
+- `Fix: Fix battery display stuck at 0% after reconnecting`
+
+### Bad Titles (too technical)
+
+- `refactor(settings): Migrate preferences to AndroidX DataStore`
+- `feat(widget): Migrate to Jetpack Glance`
+- `refactor(ui): Migrate from Fragments to Jetpack Compose`
+
+## PR Description Format
+
+### What changed
+
+User-friendly explanation of what this PR does. Describe the problem that was fixed or the feature that was added from the user's perspective. No internal class or method names.
+
+For non-user-facing PRs (refactors, tests, CI, dependency bumps): write "No user-facing behavior change" followed by a brief internal description.
+
+### Technical Context
+
+Explain what's hard to extract from the diff alone. Focus on:
+
+- **Why** this approach was chosen (and alternatives considered/rejected)
+- **Root cause** for bug fixes (the diff shows the fix, not what caused it)
+- **Non-obvious side effects** or behavioral changes not apparent from reading the code
+- **Review guidance** — what's tricky or deserves close attention
+
+Keep it scannable with bullet points. Don't restate what's visible in the diff (file names, class renames, line-level changes).
+
+### Example
+
+```markdown
+## What changed
+
+Fixed a crash that could happen when the AirPods case is opened while Bluetooth is turning off.
+
+## Technical Context
+
+- Root cause: `MonitorService` continued processing scan results during Bluetooth adapter state change, hitting a null adapter reference
+- Chose to gate on adapter state in the scan callback rather than adding a separate BroadcastReceiver, since the service already observes adapter state for restart logic
+- The timing window is ~200ms between ACTION_STATE_CHANGING and ACTION_STATE_OFF — only reproducible on Pixel devices with aggressive Bluetooth power management
+```
+
+## Conventions
+
+- **Issue references**: Use "Closes #123", "Fixes #123", or "Resolves #123"
+- **Breaking changes**: Mark with "BREAKING:" prefix if applicable
+- **No `Co-authored-by` trailers** (per project convention)