d072238fe8
- Postgres Runtime Cutover Status: 17 migrations (0000–0017), dual-write repo matrix - Backend Architecture: dual-DB architecture, repo factory, MONGO_CONNECT_MODE modes - Data Model Overview: 23-model index with PG table names and migration status - User, PurchaseRequest, SellerOffer, Chat, Dispute: Drizzle schema + cutover status added - 04 - Flows/Telegram Mini App.md: new doc covering Mini App architecture and flows - mongo-to-pg-migration-prd.md: status block prepended with 2026-06-03 milestone tracking Co-Authored-By: Claude Sonnet 4.6 <noreply@anthropic.com>
230 lines
12 KiB
Markdown
230 lines
12 KiB
Markdown
---
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title: Chat
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tags: [data-model, mongoose, postgres]
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aliases: [Conversation, IChat, IMessage]
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---
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# Chat
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> **Last updated:** 2026-06-03 — added Postgres/Drizzle schema section; migration status clarified.
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Conversation container with embedded messages. Used for buyer-seller direct chats, group chats, and support tickets. Each chat carries a list of participants, an embedded `messages[]` array (with reactions, replies, edit history), a denormalised `lastMessage` snapshot for list views, and per-user `unreadCounts`. A chat can be linked to any other entity through the `relatedTo` discriminator (currently `PurchaseRequest`, `SellerOffer`, or `Transaction`).
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> [!note] Source
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> `backend/src/models/Chat.ts:130` — chat schema definition
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> `backend/src/models/Chat.ts:69` — message subdocument schema
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> `backend/src/models/Chat.ts:348` — model export
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> `backend/src/db/schema/chat.ts` — Drizzle/Postgres schema
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> [!warning] Embedded messages
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> Messages live inside the chat document. Very long-running chats can grow past the 16 MB document limit. Treat this as a known constraint of the current schema.
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> [!warning] `relatedTo` is NOT set via `POST /api/chat`
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> Although `relatedTo` exists in the schema, it is **not accepted** by the `POST /api/chat` create endpoint. Purchase-request linkage is established server-side through the dedicated `POST /api/chat/purchase-request`, not by passing `relatedTo` to the generic create endpoint.
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> [!danger] Migration status — DUAL-WRITE, reads still on Mongo
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> Chat writes go to **both** MongoDB and Postgres (via `DrizzleChatRepo`). However, **all reads still come from MongoDB**. The Postgres `chats` table is a conservative shim: `participants` and `messages` are stored as JSONB blobs, not normalised child tables. Full normalisation (splitting messages into a separate table with proper threading) is a **known open blocker** for the Mongo → PG read cutover. Do not assume PG data is queryable relationally until that work is complete.
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## Schema — Chat (MongoDB / Mongoose)
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| Field | Type | Required | Default | Validation | Index | Description |
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| --- | --- | --- | --- | --- | --- | --- |
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| `type` | String | yes | `direct` | enum: `direct` / `group` / `support` | yes | Conversation type. |
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| `name` | String | no | — | maxlength 100 | — | Display name (group chats). |
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| `description` | String | no | — | maxlength 500 | — | Optional description. |
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| `participants[].userId` | ObjectId → [[User]] | yes | — | — | yes | Member id. |
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| `participants[].role` | String | no | `member` | enum: `member` / `admin` / `owner` | — | Member role. |
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| `participants[].joinedAt` | Date | no | `Date.now` | — | — | Join time. |
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| `participants[].lastSeen` | Date | no | — | — | — | Last activity. |
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| `participants[].leftAt` | Date | no | — | — | — | Set when the participant is removed (soft removal). |
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| `participants[].isActive` | Boolean | no | `true` | — | — | Still a participant. Set to `false` on soft removal (subdocument is kept). |
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| `messages[]` | Subdocument[] | no | `[]` | — | yes (`messages.timestamp`) | Embedded messages. |
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| `relatedTo.type` | String | no | — | enum: `PurchaseRequest` / `SellerOffer` / `Transaction` | yes (compound) | Linked entity kind. **Not accepted via `POST /api/chat`** — set only via `POST /api/chat/purchase-request`. |
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| `relatedTo.id` | ObjectId | no | — | — | yes (compound) | Linked entity id. |
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| `lastMessage.content` | String | no | — | — | — | Snapshot for list views. |
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| `lastMessage.senderId` | ObjectId → [[User]] | no | — | — | — | Last sender. |
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| `lastMessage.timestamp` | Date | no | — | — | — | Last message time. |
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| `lastMessage.messageType` | String | no | — | — | — | Last message type. |
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| `unreadCounts[].userId` | ObjectId → [[User]] | no | — | — | — | User the counter belongs to. |
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| `unreadCounts[].count` | Number | no | `0` | — | — | Number of unread messages. |
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| `settings.isArchived` | Boolean | no | `false` | — | — | Archived flag. |
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| `settings.isMuted` | Boolean | no | `false` | — | — | Muted flag. |
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| `settings.mutedUntil` | Date | no | — | — | — | Mute expiry. |
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| `settings.notifications` | Boolean | no | `true` | — | — | Per-chat notification toggle. |
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| `metadata.createdBy` | ObjectId → [[User]] | yes | — | — | — | Original creator. |
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| `metadata.createdAt` | Date | no | `Date.now` | — | — | Created timestamp. |
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| `metadata.updatedAt` | Date | no | `Date.now` | — | — | Touched by pre-save. |
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| `metadata.lastActivity` | Date | no | `Date.now` | — | yes (desc) | Sort key for chat lists. |
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> [!note] No top-level `timestamps`
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> Unlike most models, this schema does not pass `{ timestamps: true }`. It uses its own `metadata.createdAt` / `metadata.updatedAt` instead, maintained by the pre-save hook.
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> [!note] Soft removal of participants
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> Removing a participant (via `DELETE /api/chat/:id/participants/:participantId`) does **not** delete the subdocument. It is a soft removal: `isActive` is set to `false` and `leftAt` is timestamped, preserving message attribution and history.
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## Schema — Message (embedded, MongoDB)
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| Field | Type | Required | Default | Validation | Description |
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| --- | --- | --- | --- | --- | --- |
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| `senderId` | ObjectId → [[User]] | yes | — | — | Author. |
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| `senderType` | String | no | `User` | — | Currently fixed. |
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| `content` | String | yes | — | **maxlength 5000** | Message body. Enforced at both schema and controller. |
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| `messageType` | String | no | `text` | enum: `text` / `image` / `file` / `system` | Body kind. |
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| `fileUrl` | String | no | — | — | If file/image. |
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| `fileName` | String | no | — | — | Original filename. |
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| `fileSize` | Number | no | — | — | Bytes. |
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| `timestamp` | Date | no | `Date.now` | — | Sent time. |
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| `isRead` | Boolean | no | `false` | — | Read flag. |
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| `isEdited` | Boolean | no | `false` | — | Edited flag. |
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| `editedAt` | Date | no | — | — | When edited. |
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| `deletedAt` | Date | no | — | — | Set on soft-delete; `content` is cleared but the subdocument is kept. |
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| `replyTo` | ObjectId | no | — | — | Reply target message id. |
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| `reactions[].userId` | ObjectId → [[User]] | no | — | — | Reacting user. |
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| `reactions[].reaction` | String | no | — | maxlength 10 | Emoji. |
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> [!note] Messages are soft-deleted
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> Deleting a message sets `deletedAt` and clears `content` (the body becomes empty). The message subdocument is **not** physically removed from `messages[]`, and a `message-deleted` socket event is emitted.
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## Schema — `chats` table (Postgres / Drizzle)
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> Source: `backend/src/db/schema/chat.ts`
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> [!warning] Conservative JSONB shim — not normalised
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> Unlike most other migrated tables, participants and messages are stored as **JSONB blobs** (`ChatParticipant[]` and `ChatMessage[]`), not as separate relational child tables. This was a deliberate trade-off to unblock dual-write without committing to a normalisation design. The normalised schema (separate `chat_messages` and `chat_participants` tables with proper FKs and threading support) is the **primary blocker** for cutting reads over to Postgres.
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### Enums (declared in `_enums.ts`)
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| Enum | Values |
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| --- | --- |
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| `chat_type` | `direct`, `group`, `support` |
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| `chat_participant_role` | `member`, `admin`, `owner` |
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| `chat_message_type` | `text`, `image`, `file`, `system` |
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| `chat_related_to_type` | `PurchaseRequest`, `SellerOffer`, `Transaction` |
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### Table: `chats`
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| Column | PG type | Nullable | Default | Notes |
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| --- | --- | --- | --- | --- |
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| `id` | `uuid` | NOT NULL | `gen_random_uuid()` | Primary key |
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| `legacy_object_id` | `text` | nullable | — | Mongo ObjectId bridge; partial-unique index WHERE NOT NULL |
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| `type` | `chat_type` enum | NOT NULL | `'direct'` | |
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| `name` | `text` | nullable | — | Group chat display name |
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| `description` | `text` | nullable | — | |
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| `participants` | `jsonb` | nullable | — | `ChatParticipant[]` blob — **not normalised** |
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| `messages` | `jsonb` | nullable | — | `ChatMessage[]` blob — **not normalised** |
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| `related_to` | `jsonb` | nullable | — | `{ type: chat_related_to_type, id: string }` blob |
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| `last_message` | `jsonb` | nullable | — | Denormalised snapshot |
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| `unread_counts` | `jsonb` | nullable | — | `{ userId, count }[]` blob |
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| `settings_is_archived` | `boolean` | nullable | `false` | |
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| `settings_is_muted` | `boolean` | nullable | `false` | |
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| `settings_muted_until` | `timestamp with time zone` | nullable | — | |
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| `settings_notifications` | `boolean` | nullable | `true` | |
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| `created_by` | `text` | nullable | — | Mongo ObjectId or UUID string of creator |
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| `created_at` | `timestamp with time zone` | NOT NULL | `now()` | |
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| `updated_at` | `timestamp with time zone` | NOT NULL | `now()` | |
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| `last_activity` | `timestamp with time zone` | nullable | `now()` | Sort key for chat lists |
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### Indexes on `chats`
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| Index | Definition | Notes |
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| --- | --- | --- |
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| PK | `id` | |
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| partial-unique | `legacy_object_id` WHERE NOT NULL | Idempotent backfill upsert |
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| regular | `type` | |
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| regular | `created_by` | |
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| regular | `last_activity` | |
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> [!note] No FK to `users`
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> `created_by` is stored as `text` (not `uuid` FK) to accommodate both Mongo ObjectIds and PG UUIDs during the transition period.
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## Virtuals
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| Virtual | Returns | Definition |
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| --- | --- | --- |
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| `participantsCount` | Count of active participants | `backend/src/models/Chat.ts:259` |
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## Indexes (MongoDB)
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Defined at `backend/src/models/Chat.ts:243-247`:
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- `{ 'participants.userId': 1 }`
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- `{ 'metadata.lastActivity': -1 }`
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- `{ 'relatedTo.type': 1, 'relatedTo.id': 1 }`
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- `{ 'messages.timestamp': -1 }`
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- `{ type: 1 }`
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## Pre/Post Hooks
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| Hook | Behaviour |
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| --- | --- |
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| `pre('save')` (`backend/src/models/Chat.ts:250`) | Updates `metadata.updatedAt` and refreshes `metadata.lastActivity` when there are messages. |
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## Instance Methods
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| Signature | Purpose |
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| --- | --- |
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| `getUnreadCount(userId: Types.ObjectId): number` | Returns the unread counter for a participant. `backend/src/models/Chat.ts:264` |
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| `addMessage(messageData: Partial<IMessage>): IMessage` | Pushes a message, updates `lastMessage`, increments unread counters for everyone except the sender, and bumps `lastActivity`. `backend/src/models/Chat.ts:270` |
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| `markAsRead(userId, messageIds?: Types.ObjectId[]): void` | Marks listed messages (or all when `messageIds` is empty/omitted) as read for the user, zeros their unread counter, and updates `lastSeen`. `backend/src/models/Chat.ts:308` |
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## Static Methods
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None defined.
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## Relationships
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- **References**: [[User]] (`participants[].userId`, `messages[].senderId`, `messages[].reactions[].userId`, `lastMessage.senderId`, `unreadCounts[].userId`, `metadata.createdBy`).
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- **Referenced by**: [[Dispute]] (`chatId`), and any [[PurchaseRequest]] / [[SellerOffer]] indirectly through `relatedTo`.
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## Migration Status
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| Dimension | Status |
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| --- | --- |
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| Dual-write repo | `DrizzleChatRepo` — active |
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| Writes | Both MongoDB and Postgres receive writes |
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| Reads | **MongoDB only** — not yet cut over |
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| Postgres schema style | JSONB shim (participants + messages as blobs) |
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| Normalisation blocker | Chat message threading design not finalised — blocks PG read cutover |
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The normalisation work required before reads can be cut to PG:
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1. Design a `chat_messages` table with proper threading/reply support (currently `replyTo` is an ObjectId embedded in a JSONB blob)
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2. Design a `chat_participants` table (currently a JSONB blob with soft-removal semantics)
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3. Migrate reactions, edit history, and read tracking to relational rows
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4. Align unread counts with the new structure
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Until that work is complete, the Postgres `chats` table is treated as a write-ahead log / backup, not the source of truth for reads.
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## State Transitions
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No top-level status. Chat-level archival is a boolean flag (`settings.isArchived`):
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```mermaid
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stateDiagram-v2
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[*] --> active
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active --> muted : user mutes
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muted --> active : unmute / mute expires
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active --> archived : user archives
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archived --> active : restore
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```
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## Common Queries
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```ts
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// A user's recent chats
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Chat.find({ 'participants.userId': userId, 'participants.isActive': true })
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.sort({ 'metadata.lastActivity': -1 });
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// Chat for a purchase request
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Chat.findOne({ 'relatedTo.type': 'PurchaseRequest', 'relatedTo.id': prId });
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// Append a message
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const chat = await Chat.findById(id);
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chat.addMessage({ senderId, content: 'hi', messageType: 'text' });
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await chat.save();
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// Mark read
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chat.markAsRead(userId);
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await chat.save();
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```
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Related: [[User]], [[PurchaseRequest]], [[SellerOffer]], [[Dispute]].
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