docs: plan modern chat for v3.0

docs/ROADMAP.md

@@ -30,6 +30,83 @@
 
 *Prioritized for upcoming phases.*
 
+### v3.0 — Modern Room Chat
+
+- **Release date:** Not scheduled
+- **Priority:** P1
+- **Category:** Social / Communication / Privacy
+- **Status:** Planned. This is a roadmap target, not a release announcement.
+- **Existing foundation:** Opt-in, live-only end-to-end encrypted room chat; a floating
+  chat bubble over the selected player opens a dockable, detachable, resizable overlay.
+  The relay stores no chat history and mixed extension versions use capability-gated
+  delivery.
+
+#### Core experience
+
+- Floating bubble with an accessible unread badge (`1`, `2`, `3`, …, `99+`), cleared
+  only when the chat is actually viewed.
+- Subtle new-message pulse with reduced-motion support; no animation or sound while
+  muted or during Do Not Disturb.
+- Drag-and-snap bubble positioning, remembered per site, with reset-to-default.
+- Dock left/right, detached overlay, compact mode, fullscreen-safe placement, responsive
+  narrow-player layout, and keyboard-only operation.
+- Per-room mute, mention-only mode, notification sound controls, browser notifications,
+  and a visible mute state.
+- Unread state survives overlay close/reopen and tab focus changes, but room messages
+  remain memory-only unless a future storage option is explicitly enabled.
+
+#### Messaging
+
+- Replies with quoted context, emoji reactions, emoji picker, mentions, and typing
+  indicators.
+- Edit and delete own messages with clear local tombstones; no silent mutation.
+- Delivery states (`sending`, `sent`, `failed`, `retry`) with idempotent retries and
+  duplicate suppression after reconnects.
+- Message timestamps, date separators, jump-to-latest, unread divider, search within
+  the current live session, copy, and selectable text.
+- Link detection with safe external opening, explicit scheme allowlist, and no automatic
+  previews or remote-media loading.
+- Optional image/GIF/file sharing only after encrypted size limits, malware-risk UX,
+  relay bandwidth limits, and privacy behavior are designed and tested.
+
+#### Presence, safety, and control
+
+- Online/reconnecting status, join/leave events, and room-member presence without
+  exposing IP addresses or cross-room identity.
+- Local mute/block, host moderation controls, slow mode, spam limits, and configurable
+  maximum message length.
+- Optional read receipts and activity indicators default off; never infer or expose
+  viewing behavior without explicit consent.
+- Clear live-only/no-history explanation, encrypted-chat indicator, room-key fingerprint,
+  and key-rotation/rejoin UX.
+
+#### Reliability and compatibility
+
+- Versioned chat capabilities for every new wire feature; unknown fields/events remain
+  harmless to older extensions and old non-chat clients receive no chat traffic.
+- Server-first and extension-first rollout tests, including current, first-chat-beta,
+  old non-chat, reconnect, duplicate-frame, and malformed-capability clients.
+- Bounded queues, payloads, unread counters, typing events, reactions, and attachment
+  metadata; backpressure and rate limits on both client and relay.
+- Real Chrome and Firefox extension E2E coverage for bubble, unread count, overlay,
+  fullscreen, reconnect, and mixed-version rooms before v3.0 can ship.
+
+#### Accessibility and localization
+
+- Screen-reader announcements that do not read every busy-room message by default.
+- Complete focus management, logical tab order, Escape behavior, high contrast,
+  zoom/reflow, reduced motion, and touch target coverage.
+- All chat UI, notification text, moderation states, and errors localized across every
+  supported locale before release.
+
+#### Explicit non-goals for the first v3.0 release
+
+- No server-readable plaintext.
+- No mandatory accounts, public room directory, advertising, tracking, or presence
+  across rooms.
+- No unencrypted server-side history. Any future encrypted history requires a separate
+  threat model, retention controls, export/delete behavior, and explicit opt-in.
+
 ### 2. Invite link with target URL for auto-redirect
 
 - **Priority:** P2
@@ -49,17 +126,6 @@
 
 *Ideas and feature requests under evaluation.*
 
-### In-room chat overlay (like TeleParty)
-
-- **Priority:** P3
-- **Category:** Social / Communication
-- **Background:** A collapsible chat panel to the right of the video (or as an overlay) allowing text-based communication with everyone in the room.
-- **Why backlog (still uncertain):**
-  - **Use case:** No strong personal need — with chat, latency matters less than with voice; async communication tolerates a few seconds of delay.
-  - **Complexity:** Relatively large feature (UI + message persistence + possibly history).
-  - **Legal/moderation:** Unclear what moderation requirements would apply if users can exchange chat messages. Could be relevant depending on jurisdiction.
-- **Status:** Under evaluation, may come later.
-
 ### Cross-frame video detection and control
 
 - **Priority:** P3