feat(platform): route scheduler notifications through platform messenger

docs/adr/002-platform-neutral-batch-rendering.md

@@ -30,7 +30,7 @@ SessionBatchViewModel (platform-neutral)
     │
     ├──► TelegramSessionBatchRenderer ──► HTML + InlineKeyboardMarkup
     │
-    └──► DiscordSessionBatchRenderer ──► (issue #26)
+    └──► DiscordSessionBatchRenderer ──► Discord embeds + buttons
 ```
 
 ### Изменённые компоненты
@@ -41,7 +41,7 @@ SessionBatchViewModel (platform-neutral)
 | `SessionBatchViewBuilder` | — | `GmRelay.Shared.Rendering` |
 | `SessionBatchViewModel` | — | `GmRelay.Shared.Rendering` |
 | `TelegramSessionBatchRenderer` | — | `GmRelay.Bot` + `GmRelay.Web` |
-| `DiscordSessionBatchRenderer` | — | `GmRelay.Shared.Rendering` (stub) |
+| `DiscordSessionBatchRenderer` | — | `GmRelay.DiscordBot.Rendering` |
 | `BatchMessageEditor` | `GmRelay.Shared.Rendering` | `GmRelay.Bot` + `GmRelay.Web` |
 
 ## Consequences
@@ -49,7 +49,7 @@ SessionBatchViewModel (platform-neutral)
 ### Positive
 
 - `GmRelay.Shared` больше не зависит от `Telegram.Bot`. Чистый platform-agnostic проект.
-- Можно добавить `DiscordSessionBatchRenderer` без изменений в `Shared`.
+- Discord renderer lives in `GmRelay.DiscordBot`, so NetCord stays out of `Shared`.
 - Unit-тесты ViewBuilder не создают `InlineKeyboardMarkup`.
 - Логика подсчёта игроков, сортировки сессий и генерации действий — в одном месте (ViewBuilder).
 
@@ -62,4 +62,5 @@ SessionBatchViewModel (platform-neutral)
 
 - Issue #22 — этот рефакторинг.
 - Issue #26 — Discord Bot MVP (потребитель новой архитектуры).
+- Issue #31 — scheduler notifications and reschedule deadline updates now use `IPlatformMessenger` for Telegram and Discord.
 - ADR 001 — vertical slice, native AOT, Aspire (`docs/adr/0001-use-vertical-slice-native-aot-and-aspire.md`).

docs/c4-system-context.md

@@ -18,11 +18,11 @@ C4Context
     Rel(gm, telegram, "Creates and manages sessions")
     Rel(gm, discord, "Uses /newsession and /listsessions")
     Rel(player, telegram, "Uses inline buttons")
-    Rel(player, discord, "Uses Join/Leave buttons")
+    Rel(player, discord, "Uses Join/Leave and RSVP buttons")
     Rel(telegram, gmrelay, "Updates via long polling")
     Rel(discord, gmrelay, "Gateway events and component interactions")
     Rel(gmrelay, telegram, "SendMessage, EditMessage, AnswerCallbackQuery")
-    Rel(gmrelay, discord, "Send/edit schedule messages and ephemeral interaction replies")
+    Rel(gmrelay, discord, "Send/edit schedule, RSVP, reminder, and reschedule messages")
     Rel(gmrelay, postgres, "SQL via Npgsql and Dapper")
 ```
 
@@ -37,9 +37,9 @@ C4Container
 
     System_Boundary(runtime, "Docker Compose / Aspire runtime") {
         Container(bot, "GmRelay.Bot", "Worker Service, .NET 10 AOT", "Telegram long polling, commands, callback routing, reminders")
-        Container(discordBot, "GmRelay.DiscordBot", "Worker Service, .NET 10", "NetCord Gateway, slash commands, Join/Leave button interactions")
+        Container(discordBot, "GmRelay.DiscordBot", "Worker Service, .NET 10", "NetCord Gateway, slash commands, scheduler notifications, and button interactions")
         Container(web, "GmRelay.Web", "Blazor Server", "Dashboard, Mini App pages, editing and stats")
-        Container(shared, "GmRelay.Shared", ".NET library", "Shared domain models, rendering, and platform-neutral join/leave handlers")
+        Container(shared, "GmRelay.Shared", ".NET library", "Shared domain models, rendering, scheduler, and platform-neutral handlers")
         ContainerDb(db, "PostgreSQL", "Database", "sessions, players, session_participants, game_groups, platform identities")
     }
 
@@ -55,7 +55,7 @@ C4Container
     Rel(bot, telegram, "Bot API calls")
     Rel(discordBot, discord, "REST send/edit/reply calls")
     Rel(bot, shared, "Uses shared renderers and join/leave handlers")
-    Rel(discordBot, shared, "Uses shared renderers and join/leave handlers")
+    Rel(discordBot, shared, "Uses shared renderers, scheduler, and platform-neutral handlers")
     Rel(web, shared, "Uses shared domain and rendering models")
     Rel(bot, db, "Npgsql + Dapper.AOT")
     Rel(discordBot, db, "Npgsql + Dapper")
@@ -71,18 +71,20 @@ C4Component
     Container_Boundary(shared, "GmRelay.Shared") {
         Component(join, "JoinSessionHandler", "Feature handler", "Adds players as Active or Waitlisted with session row locking")
         Component(leave, "LeaveSessionHandler", "Feature handler", "Removes players and promotes the first waitlisted player when capacity allows")
+        Component(rsvp, "HandleRsvpHandler", "Feature handler", "Updates RSVP state and emits platform-neutral RSVP outcomes")
+        Component(scheduler, "SessionSchedulerService", "Background service", "Triggers confirmation, reminder, and join-link notifications per platform")
         Component(updateLock, "ScheduleMessageUpdateLock", "In-memory keyed lock", "Serializes DB changes and schedule message edits per platform message")
         Component(renderer, "SessionBatchViewBuilder", "Renderer model builder", "Builds platform-neutral schedule views and actions")
     }
 
     Container_Boundary(discordBot, "GmRelay.DiscordBot") {
-        Component(discordModule, "DiscordSessionInteractionModule", "NetCord component module", "Maps join_session/leave_session buttons to neutral commands")
-        Component(discordMessenger, "DiscordPlatformMessenger", "IPlatformMessenger", "Edits Discord schedule messages and stores interaction replies")
+        Component(discordModule, "DiscordSessionInteractionModule", "NetCord component module", "Maps join_session/leave_session/rsvp buttons to neutral commands")
+        Component(discordMessenger, "DiscordPlatformMessenger", "IPlatformMessenger", "Sends and edits Discord schedule, RSVP, reminder, join-link, and reschedule messages")
     }
 
     Container_Boundary(bot, "GmRelay.Bot") {
         Component(updateRouter, "UpdateRouter", "Telegram adapter", "Maps callback queries to neutral commands")
-        Component(telegramMessenger, "TelegramPlatformMessenger", "IPlatformMessenger", "Edits Telegram schedule messages and answers callback queries")
+        Component(telegramMessenger, "TelegramPlatformMessenger", "IPlatformMessenger", "Sends and edits Telegram schedule, RSVP, reminder, join-link, and reschedule messages")
     }
 
     ContainerDb(db, "PostgreSQL")
@@ -92,19 +94,27 @@ C4Component
     Rel(discord, discordModule, "Button interaction")
     Rel(discordModule, join, "JoinSessionCommand")
     Rel(discordModule, leave, "LeaveSessionCommand")
+    Rel(discordModule, rsvp, "HandleRsvpCommand")
     Rel(discordModule, discord, "Deferred ephemeral reply, then modify response")
     Rel(updateRouter, join, "JoinSessionCommand")
     Rel(updateRouter, leave, "LeaveSessionCommand")
+    Rel(updateRouter, rsvp, "HandleRsvpCommand")
     Rel(join, updateLock, "Acquire by PlatformMessageRef")
     Rel(leave, updateLock, "Acquire by PlatformMessageRef")
     Rel(join, db, "SELECT FOR UPDATE, INSERT participant")
     Rel(leave, db, "SELECT FOR UPDATE, DELETE/promote participant")
+    Rel(rsvp, db, "Update RSVP and load notification recipients")
+    Rel(scheduler, db, "Load due session triggers")
     Rel(join, renderer, "Build updated schedule view")
     Rel(leave, renderer, "Build updated schedule view")
     Rel(join, discordMessenger, "Update Discord schedule when command is Discord")
     Rel(leave, discordMessenger, "Update Discord schedule when command is Discord")
     Rel(join, telegramMessenger, "Update Telegram schedule when command is Telegram")
     Rel(leave, telegramMessenger, "Update Telegram schedule when command is Telegram")
-    Rel(discordMessenger, discord, "ModifyMessage + ephemeral text")
-    Rel(telegramMessenger, telegram, "EditMessage + AnswerCallbackQuery")
+    Rel(rsvp, discordMessenger, "Update Discord confirmation and outcomes")
+    Rel(rsvp, telegramMessenger, "Update Telegram confirmation and outcomes")
+    Rel(scheduler, discordMessenger, "Send Discord scheduler notifications")
+    Rel(scheduler, telegramMessenger, "Send Telegram scheduler notifications")
+    Rel(discordMessenger, discord, "REST send/edit/DM + ephemeral text")
+    Rel(telegramMessenger, telegram, "SendMessage/EditMessage + AnswerCallbackQuery")
 ```