chat_grid/docs/runtime-flow.md

Runtime Flow

Connect Flow

1. User clicks connect.
2. Client validates auth form and sets up local media.
3. Client connects signaling websocket from the configured app origin.
4. Server accepts the socket only when the browser Origin matches CHGRID_HOST_ORIGIN, then attempts cookie-based session resume from websocket handshake cookie (chgrid_session_token).
5. If resume does not authenticate, server sends auth_required.
   • includes authPolicy limits for username/password.
6. Client sends auth_login or auth_register (or explicit auth_resume if provided by caller).
7. Server sends auth_result.
   • includes role + permissions for authenticated session.
8. Client persists authenticated session into a server-managed HttpOnly cookie via GET /auth/session/set (Authorization: Bearer <sessionToken>, X-Chgrid-Auth-Client: 1), and clears it via GET /auth/session/clear (X-Chgrid-Auth-Client: 1) on logout/session errors.
9. Server sends welcome with users/items snapshot.
10. Client:

• applies welcome.worldConfig.gridSize for authoritative grid bounds/rendering
• applies welcome.worldConfig.movementTickMs as movement pacing guidance
• applies welcome.worldConfig.movementMaxStepsPerTick for movement-rate parity
• uses welcome.player as authoritative starting position (restored from server-side account state when available)
• records welcome.serverInfo (instanceId, version) for restart detection
• if welcome.serverInfo.version differs from running client version, auto-reloads the page
• applies welcome.uiDefinitions for item menus/properties/options, server-backed command metadata, item-management metadata, and admin menu labels/order
• sends initial update_position echo from server-assigned starting tile
• sends initial update_nickname
• creates peer runtimes for known users
• syncs item runtimes (radio, emit)
• applies audio layer state
• starts signaling heartbeat monitor
• starts game loop

Main Loop

Each frame:

• Handle local movement input.
• Send movement intents; server remains authoritative on accepted movement updates.
• Update spatial voice audio.
• Update spatial radio audio.
• Update spatial item emit audio.
• Draw canvas scene.

Message Handling

Core incoming message effects:

• signal: WebRTC negotiation and ICE exchange.
• auth_required: prompt client to authenticate before gameplay messages.
• auth_result: auth success/failure with optional session token + account metadata + authPolicy.
• auth_permissions: live permission refresh (role + permission set) after role/permission admin changes.
• admin_roles_list: role metadata + user counts + permission keys for role management UI.
• admin_users_list: user metadata list for role/ban admin flows.
• admin_action_result: success/error for role/user admin mutations.
• update_position: update peer position; may play movement/teleport world sound.
• teleport_complete: play peer teleport landing sound at final tile.
• update_nickname: update peer display name.
• chat_message: append/readable status; optional system sound class.
• item_upsert: replace item snapshot and resync item runtimes.
• item_remove: remove item and cleanup runtimes.
• item_action_result: success/error status for actions.
• item_use_sound: play one-shot spatial sample (world layer gated).
• item_piano_note: start/stop synthesized piano notes from remote users (item layer gated).
• item_piano_status: structured piano mode/record/playback transitions (client runtime state).
• pong:
  • positive clientSentAt: user ping response (P command)
  • negative clientSentAt: internal heartbeat response

Stale Connection Recovery

• If websocket closes unexpectedly, client starts reconnect flow immediately.
• While running, client also sends heartbeat ping every 10 seconds (fallback for silent half-open cases).
• If one heartbeat pong is missed (10-second interval), client starts reconnect flow.
• Reconnect flow waits 5 seconds and retries up to 3 times.
• If reconnect lands on a different welcome.serverInfo.instanceId, client announces server restart.
• Connect/reconnect status message is emitted from welcome and includes server version.

Authorization Runtime

• Server enforces item/chat/nickname/voice/admin permissions for each packet.
• Role and permission changes apply live to connected users without reconnect.
• voice.send revocation is pushed immediately via auth_permissions; client mutes outbound voice track.

Disconnect/Cleanup

On disconnect:

• Close signaling.
• Stop heartbeat monitor.
• Stop local media tracks.
• Cleanup peers and all audio runtimes.
• Reset UI/mode state and lists.

Runtime Components

• PeerManager: peer connection lifecycle and remote track attach.
• RadioStationRuntime: shared stream sources + per-item output/effects/spatialization.
• ItemEmitRuntime: per-item looping emit source + spatialization.
• AudioEngine: shared audio context, samples, effects, voice graph.