docs: rewrite README with feature-parity matrix for desktop vs mobile (#44)

The previous README still described mobile as a "Capacitor scaffold (stub Platform; persistence and native plugins pending)" — wildly stale after Phases 4-7 shipped. Re-anchor it on what actually works today and where the two shells diverge.

- Spell out the unified-UX goal: shell is shared, runtimes inject a Platform. State the one expected divergence point: offline editing (desktop cache-then-OT-replay vs mobile CRDT local-edit-queue).
- Add a 7-section feature matrix (~40 rows) covering workspaces, pads/tabs, deep links, settings/i18n, keyboard/gestures, permissions, packaging, tests. Empty / ⏳ / ✅ keys per shell.
- Update package status (mobile is no longer "Capacitor scaffold").
- Add a What's-Next section grouped Soon / Later / Non-goals, with the offline-editing divergence flagged explicitly.
- Keep quick-start commands inline and point per-package READMEs at developer docs.

Author: JohnMcLear

README.md

@@ -1,31 +1,192 @@
 # Etherpad apps
 
-Cross-platform clients for [Etherpad](https://etherpad.org/) — currently desktop, with mobile in development.
+Cross-platform clients for [Etherpad](https://etherpad.org/) — a single codebase
+that ships as an Electron desktop app **and** a Capacitor Android app, both
+running the same React shell.
 
 This is a pnpm monorepo.
 
 | Package | Status | Source |
 |---|---|---|
-| `@etherpad/desktop` | Released | [`packages/desktop`](packages/desktop) |
-| `@etherpad/shell` | Source-consumed workspace dep | [`packages/shell`](packages/shell) |
-| `@etherpad/mobile` | Capacitor scaffold (stub Platform; persistence and native plugins pending) | [`packages/mobile`](packages/mobile) |
+| `@etherpad/desktop` | v0 beta — Linux (AppImage / `.deb` / Snap), Windows (NSIS / portable), macOS (DMG arm64+x64). Auto-update on Linux + Windows. | [`packages/desktop`](packages/desktop) |
+| `@etherpad/mobile` | Beta — Android debug APK runs; iOS scaffold present, not yet exercised. Not on Play Store yet. | [`packages/mobile`](packages/mobile) |
+| `@etherpad/shell` | Workspace dep consumed as source by both apps. Owns React tree, state, i18n, IPC channel schemas, the `Platform` injection seam. | [`packages/shell`](packages/shell) |
 
-## Quick start (desktop)
+## Goal
+
+**One UX, two shells.** The instance rail, pad tabs, sidebar, dialogs, settings,
+keyboard model, theming, and i18n live in `@etherpad/shell` and render
+identically on desktop and mobile. Each runtime injects a `Platform`
+implementation that handles native concerns (window management, persistence,
+deep links, permissions) behind a typed IPC seam.
+
+The one place we expect to **diverge** is offline editing — a desktop client
+usually has a long-lived connection, where a mobile client is offline by
+default. Mobile will likely grow a CRDT-based local-edit-queue path that
+desktop doesn't need; both will keep using Etherpad's OT-based collaboration
+when online.
+
+## Quick start
 
 ```bash
 pnpm install
-pnpm dev
+pnpm dev               # desktop: Electron + Vite HMR
+pnpm mobile:dev        # mobile: browser preview at http://localhost:5173/
+pnpm mobile:android:run # mobile: build + sync + run on attached device/emulator
+pnpm test              # vitest across all packages
+pnpm test:e2e          # Playwright Electron e2e + mobile smoke
+pnpm typecheck         # tsc -b across the monorepo
 ```
 
-See [`packages/desktop/README.md`](packages/desktop/README.md) for full developer documentation.
+Per-app developer docs:
+
+- [`packages/desktop/README.md`](packages/desktop/README.md) — install one-liners, install matrix, dev loop, packaging.
+- [`packages/mobile/README.md`](packages/mobile/README.md) — Capacitor / Android toolchain, build + adb.
+
+## Feature parity
 
-## Layout
+This is the canonical "what works where" view. Empty cells mean **not started**;
+"⏳" means in flight; "✅" means shipped on that surface.
 
-- `packages/desktop/` — Electron app (Linux AppImage, deb, snap; macOS DMG; Windows NSIS).
-- `packages/shell/` — React renderer shell shared between desktop and mobile. Owns dialogs, state, i18n, and the `Platform` injection seam.
-- `packages/mobile/` — Capacitor 8 Android (and iOS-ready) app. Vite-built, wraps `@etherpad/shell` via `createCapacitorPlatform()`. `pnpm mobile:dev` for a browser preview; `pnpm mobile:android:run` for an attached device/emulator.
-- `docs/` — specs, plans, and shared internal docs.
+### Etherpad instances and workspaces
+
+| Feature | Desktop | Mobile |
+|---|---|---|
+| Multiple Etherpad instances, isolated sessions | ✅ | ✅ |
+| Per-instance colour + name + URL editing | ✅ | ✅ |
+| Reorder instances in the rail | ✅ | ✅ |
+| Embedded local Etherpad server (no internet needed) | ✅ | ❌ phones don't ship Node; spec divergence noted below |
+| HTTP basic-auth challenge dialog | ✅ | ❌ planned |
+
+### Pads, tabs, navigation
+
+| Feature | Desktop | Mobile |
+|---|---|---|
+| Open pad by name into a new tab | ✅ | ✅ |
+| Multiple pads per instance, switchable tabs | ✅ | ✅ |
+| Auto-collapse rail when opening a pad (focus mode) | ✅ | ✅ |
+| Tap pad to dismiss the rail (drawer behaviour) | n/a | ✅ |
+| Restore open tabs + active pad across app restarts | ✅ | ✅ |
+| Restore rail-collapsed state across app restarts | ✅ | ✅ |
+| Native pad rendering (WebContentsView vs iframe) | WebContentsView | iframe |
+| Pad sidebar — Recent + Pinned + search | ✅ | ✅ |
+| Cross-instance fuzzy quick switcher (Ctrl+K) | ✅ name + content search | ✅ name search; content search ⏳ |
+| Pad-history persistence per workspace | ✅ | ✅ |
+| `?lang=…&userName=…` threaded into pad URL | ✅ | ✅ |
+
+### Deep links and integration
+
+| Feature | Desktop | Mobile |
+|---|---|---|
+| `etherpad-app://` deep-link scheme | ✅ registered, partial handler | ✅ |
+| Open pad by URL dialog | ✅ | ✅ |
+| Receive shared URL from another app | n/a | ✅ Android share intent |
+| "Open in browser" escape for blocked / X-Frame-DENY pads | n/a | ✅ |
+
+### Settings, theming, i18n
+
+| Feature | Desktop | Mobile |
+|---|---|---|
+| Light / dark / auto theme | ✅ | ✅ |
+| Default zoom override | ✅ | ✅ |
+| Accent colour override | ✅ | ✅ |
+| User display name pre-fill | ✅ | ✅ |
+| "Remember open pads on quit" toggle | ✅ | ✅ |
+| Confirmation dialog before "Clear all pad history" | ✅ | ✅ |
+| Shell strings translated (en, es, fr, de, pt/pt-br, it) | ✅ | ✅ |
+| Pad-iframe locale via `?lang=` (115 etherpad-core locales) | ✅ | ✅ |
+| HTML root `lang` attribute follows active locale | ✅ | ✅ |
+
+### Keyboard, gestures, window
+
+| Feature | Desktop | Mobile |
+|---|---|---|
+| Keyboard shortcuts (`Ctrl+T` / `Ctrl+W` / `Ctrl+K` / `Ctrl+1..9` / `Ctrl+,`) | ✅ | n/a |
+| Swipe gesture between pads | n/a | ✅ |
+| Android back button collapses → switches → exits | n/a | ✅ |
+| Window bounds + active workspace restored on relaunch | ✅ | n/a |
+| Minimise-to-tray | ✅ | n/a |
+| Tray icon (B&W silhouette, theme-adaptive ⏳) | ✅ | n/a |
+
+### Permissions and security
+
+| Feature | Desktop | Mobile |
+|---|---|---|
+| Per-instance isolated session partition | ✅ `persist:ws-<uuid>` | ✅ Capacitor Preferences keyed by workspace id |
+| Permission pre-allow for `ep_webrtc` plugins (cam/mic/fullscreen/clipboard/screen) | ✅ narrow allowlist | ⏳ Phase 6b native plugin (camera/mic delegation) |
+| Deny-by-default with prompt-on-request, persisted decisions | ⏳ planned | ⏳ planned |
+| HTTPS-with-self-signed-cert trust UX | ⏳ planned | ⏳ planned |
+
+### Packaging, distribution, updates
+
+| Feature | Desktop | Mobile |
+|---|---|---|
+| Linux AppImage + `.deb` + Snap | ✅ | n/a |
+| Windows NSIS installer + portable `.exe` | ✅ unsigned | n/a |
+| macOS DMG (arm64 + x64) | ✅ unsigned | n/a |
+| Android signed release APK + Play Store listing | n/a | ⏳ |
+| iOS build | n/a | scaffold present, not built |
+| `release-please` conventional-commits release flow | ✅ | shared release flow planned |
+| In-app auto-update | ✅ electron-updater (AppImage + `.deb` + Windows NSIS) | n/a — store handles updates |
+| Snap channel publishing (`edge` auto, `stable` gated) | ✅ | n/a |
+
+### Tests and CI
+
+| Feature | Desktop | Mobile |
+|---|---|---|
+| Vitest unit + component tests | ✅ | ✅ shared with shell |
+| Playwright Electron e2e | ✅ against in-process mock Etherpad | n/a |
+| Playwright web smoke (vite preview) | n/a | ✅ |
+| Android emulator click-through smoke (uiautomator) | n/a | ✅ scaffolded |
+| CI runs on every PR (lint / typecheck / unit / e2e) | ✅ | ✅ |
+
+## What's next
+
+Roughly in the order it'll be tackled. Items that apply to one shell are
+marked; everything else lands on both.
+
+### Soon
+
+- **Mobile permissions plugin (Phase 6b)** — native Kotlin delegation for
+  camera, mic, clipboard, fullscreen, file picker so `ep_webrtc` and friends
+  work inside the WebView on Android.
+- **Desktop permission UX upgrade** — replace the narrow pre-allow with a
+  deny-by-default prompt-on-request flow, decisions persisted per
+  instance+origin. Same UI ships to mobile after Phase 6b lands.
+- **Mobile content search in quick switcher** — desktop already indexes pad
+  bodies via `/export/txt`. Mobile stubs that path; wire it.
+- **Mobile Play Store release** — signed AAB, store listing, edge / stable
+  channels mirroring the Snap split.
+- **Cross-pad content search on mobile** — see above.
+- **Tray icon theme adaptation (desktop)** — detect `nativeTheme`, ship a
+  black-silhouette variant for light trays.
+
+### Later
+
+- **Offline editing — diverges between shells.** Desktop usually has a
+  long-lived connection; mobile is offline by default. Working assumption:
+  desktop gets a cache-then-OT-replay path; mobile gets a CRDT-based local
+  edit queue with sync-on-reconnect. Both surface the same UX (greyed
+  "offline" banner, queued-edit indicator) but the engines differ. Spec work
+  in flight.
+- **Native OS notifications** — pad mentions, presence.
+- **Drag-tab-to-reorder + tear-off-into-new-window** (desktop).
+- **HTTPS-with-self-signed-cert trust UX** — applies to both, more useful on
+  desktop where users add local Etherpad URLs.
+
+### Explicit non-goals
+
+- **No code-signing fees.** Windows + macOS will continue shipping unsigned
+  binaries — SmartScreen / Gatekeeper warn on first run; both work fine
+  afterwards. Apple's $99/yr Developer ID and Microsoft's EV / Azure Trusted
+  Signing programs gate independent open-source software behind a recurring
+  tax we won't pay. Forks / distributors / enterprises are welcome to roll
+  their own signed builds under Apache-2.0.
 
 ## License
 
 Apache-2.0. See [LICENSE](LICENSE) and [NOTICE](NOTICE).
+
+This project is a thin client; the Etherpad server is upstream software with
+its own license and contributors. Etherpad is at
+<https://github.com/ether/etherpad>.