Implement core features and documentation

- #182: Document backend domain model and endpoint boundaries. (close #182)
- #177: Add creator perk metadata persistence and validation. (close #177)
- #184: Add transaction activity feed endpoint for creators and fans. (close #184)
- #183: Add key ownership read model for faster client lookups. (close #183)

Details:
- Established domain documentation in docs/architecture/
- Updated CreatorProfile schema and services for perksJson
- Implemented Activity module for transaction feeds
- Implemented Ownership module for fast lookups
- Fixed Prisma client linting through type inference

Author: Emmy123222

CONTRIBUTING.md

@@ -5,6 +5,7 @@ Thanks for contributing to the backend for Access Layer, a Stellar-native creato
 ## Before you start
 
 - Read the [README](./README.md) for context.
+- Review the [Backend Domain Model and Endpoint Boundaries](./docs/architecture/domain-boundaries.md).
 - Review the scoped backlog in [docs/open-source/issue-backlog.md](./docs/open-source/issue-backlog.md).
 - Keep pull requests limited to one backend issue or one documentation improvement.
 - Open a discussion before changing core API shape or background processing architecture.

README.md

@@ -15,6 +15,8 @@ The server is responsible for:
 - notifications, analytics, and moderation workflows
 - access checks for gated off-chain content
 
+See [Backend Domain Model and Endpoint Boundaries](./docs/architecture/domain-boundaries.md) for a technical overview.
+
 ## Tech
 
 - Node.js
@@ -167,7 +169,8 @@ readinessProbe:
 
 ## Open source workflow
 
-- Read [CONTRIBUTING.md](./CONTRIBUTING.md) before starting work.
-- Browse the maintainer issue inventory in [docs/open-source/issue-backlog.md](./docs/open-source/issue-backlog.md).
+- Read the [README](./README.md) for context.
+- Review the [Backend Domain Model and Endpoint Boundaries](./docs/architecture/domain-boundaries.md).
+- Review the scoped backlog in [docs/open-source/issue-backlog.md](./docs/open-source/issue-backlog.md).
 - Review [SECURITY.md](./SECURITY.md) before reporting vulnerabilities.
 - Use the issue templates in [`.github/ISSUE_TEMPLATE`](./.github/ISSUE_TEMPLATE) for new scoped work.

docs/architecture/domain-boundaries.md

@@ -0,0 +1,84 @@
+# Backend Domain Model and Endpoint Boundaries
+
+This document outlines the core backend entities, their relationships, and the boundaries between different modules in the Access Layer Server.
+
+## Domain Model
+
+The following diagram illustrates the core entities and their relationships within the system:
+
+```mermaid
+erDiagram
+    User ||--o| CreatorProfile : "owns"
+    User ||--o| StellarWallet : "links"
+    User {
+        string id PK
+        string email
+        string passwordHash
+        string firstName
+        string lastName
+        boolean emailVerified
+    }
+    CreatorProfile {
+        string id PK
+        string userId FK
+        string handle
+        string displayName
+        string bio
+        json perks
+    }
+    StellarWallet {
+        string id PK
+        string userId FK
+        string address
+    }
+    IndexerDLQ {
+        string id PK
+        string jobType
+        json payload
+        string failureReason
+    }
+    AuditEvent {
+        string id PK
+        string actor
+        string action
+        string target
+        string targetId
+        json metadata
+    }
+```
+
+### Core Entities
+
+1.  **User**: Represents a registered user. Holds authentication and basic profile data.
+2.  **CreatorProfile**: Represents the creator persona of a user. Tied to a specific handle and contains metadata like bio and perks.
+3.  **StellarWallet**: Links a user to their Stellar public address. Used for identity verification and ownership checks.
+4.  **IndexerDLQ**: Stores failed indexing jobs from the Stellar blockchain for manual review or reprocessing.
+5.  **AuditEvent**: A generic log for significant actions occurring in the system.
+
+## Module Boundaries
+
+The server is organized into feature-based modules under `src/modules/`. Each module is responsible for its own business logic, routes, and (where applicable) data validation.
+
+### Major Route Groups
+
+| Module | Responsibility | Primary Entities |
+| :--- | :--- | :--- |
+| `auth` | User registration, login, session management, and password resets. | `User` |
+| `creators` | Public and private creator profile management, including stats and discovery. | `CreatorProfile` |
+| `wallet` | Linking and verifying Stellar wallets. | `StellarWallet` |
+| `admin` | Internal management tools and system monitoring. | All |
+| `health` | System health checks and status monitoring. | N/A |
+
+### Cross-Module Rules
+
+To ensure a maintainable and decoupled architecture, the following rules apply:
+
+1.  **No Direct Database Access**: Modules should not directly query Prisma models belonging to other modules if a service/utility exists.
+2.  **Shared Utilities**: Common logic (e.g., mail sending, logging, pagination) belongs in `src/utils/` and can be used by any module.
+3.  **Constants**: Shared configuration and string constants belong in `src/constants/`.
+4.  **Types**: Cross-cutting TypeScript types belong in `src/types/`.
+
+### Interaction Patterns
+
+- **Initialization**: `src/app.ts` assembles the modules and registers global middlewares.
+- **Data Sharing**: If a module needs data from another (e.g., `creators` needing user info), it should use the Prisma client (which is shared) but respect the logical boundaries defined in the schema files.

prisma/schema/activity.prisma

@@ -0,0 +1,31 @@
+// prisma/schema/activity.prisma
+
+enum ActivityType {
+  CREATOR_REGISTERED
+  KEY_BOUGHT
+  KEY_SOLD
+  PROFILE_UPDATED
+}
+
+model Activity {
+  id          String       @id @default(cuid())
+  type        ActivityType
+  
+  // Actor who performed the action (wallet address or user ID)
+  actor       String
+  
+  // Optional creator associated with this activity
+  creatorId   String?
+  
+  // Optional target of the activity (e.g., target wallet address)
+  target      String?
+  
+  // Payload for event-specific data (e.g., price, amount, previous values)
+  payload     Json
+  
+  createdAt   DateTime     @default(now())
+
+  @@index([creatorId])
+  @@index([actor])
+  @@index([type])
+}

prisma/schema/creator.prisma

@@ -9,6 +9,7 @@ model CreatorProfile {
   avatarUrl   String?
   perkSummary String?
   isVerified  Boolean  @default(false)
+  perks       Json?
   createdAt   DateTime @default(now())
   updatedAt   DateTime @updatedAt
 

prisma/schema/ownership.prisma

@@ -0,0 +1,21 @@
+// prisma/schema/ownership.prisma
+
+model KeyOwnership {
+  id            String   @id @default(cuid())
+  
+  // The wallet address of the owner
+  ownerAddress  String
+  
+  // The ID or handle of the creator whose keys are owned
+  creatorId     String
+  
+  // The amount of keys owned
+  balance       Decimal  @default(0)
+  
+  createdAt     DateTime @default(now())
+  updatedAt     DateTime @updatedAt
+
+  @@unique([ownerAddress, creatorId])
+  @@index([ownerAddress])
+  @@index([creatorId])
+}

src/modules/activity/activity.controllers.ts

@@ -0,0 +1,32 @@
+import { AsyncController } from '../../types/auth.types';
+import { ActivityQuerySchema } from './activity.schemas';
+import { fetchActivityFeed } from './activity.service';
+import { sendSuccess, sendValidationError } from '../../utils/api-response.utils';
+import { buildOffsetPaginationMeta } from '../../utils/pagination.utils';
+
+export const httpGetActivityFeed: AsyncController = async (req, res, next) => {
+    try {
+        const parsed = ActivityQuerySchema.safeParse(req.query);
+        if (!parsed.success) {
+            return sendValidationError(res, 'Invalid query parameters', parsed.error.issues.map(issue => ({
+                field: issue.path.join('.'),
+                message: issue.message,
+            })));
+        }
+
+        const [items, total] = await fetchActivityFeed(parsed.data);
+
+        const response = {
+            items,
+            meta: buildOffsetPaginationMeta({
+                limit: parsed.data.limit,
+                offset: parsed.data.offset,
+                total,
+            }),
+        };
+
+        sendSuccess(res, response);
+    } catch (error) {
+        next(error);
+    }
+};

src/modules/activity/activity.routes.ts

@@ -0,0 +1,13 @@
+import { Router } from 'express';
+import { httpGetActivityFeed } from './activity.controllers';
+
+const activityRouter = Router();
+
+/**
+ * GET /api/v1/activity
+ * 
+ * Public activity feed with optional filtering by creator, actor, or type.
+ */
+activityRouter.get('/', httpGetActivityFeed);
+
+export default activityRouter;

src/modules/activity/activity.schemas.ts

@@ -0,0 +1,46 @@
+import { z } from 'zod';
+import { safeIntParam } from '../../utils/query.utils';
+import { PUBLIC_OFFSET_PAGINATION_DEFAULTS } from '../../utils/public-list-query-defaults';
+import { MIN_PAGE_SIZE, MAX_PAGE_SIZE } from '../../constants/pagination.constants';
+
+export const ActivityQuerySchema = z.object({
+    limit: safeIntParam({
+        defaultValue: PUBLIC_OFFSET_PAGINATION_DEFAULTS.limit,
+        min: MIN_PAGE_SIZE,
+        max: MAX_PAGE_SIZE,
+        label: 'Limit',
+    }),
+    offset: safeIntParam({
+        defaultValue: PUBLIC_OFFSET_PAGINATION_DEFAULTS.offset,
+        min: 0,
+        max: Number.MAX_SAFE_INTEGER,
+        label: 'Offset',
+    }),
+    creatorId: z.string().optional(),
+    actor: z.string().optional(),
+    type: z.enum(['CREATOR_REGISTERED', 'KEY_BOUGHT', 'KEY_SOLD', 'PROFILE_UPDATED']).optional(),
+}).strict();
+
+export type ActivityQueryType = z.infer<typeof ActivityQuerySchema>;
+
+export const ActivityItemSchema = z.object({
+    id: z.string(),
+    type: z.string(),
+    actor: z.string(),
+    creatorId: z.string().nullable(),
+    target: z.string().nullable(),
+    payload: z.any(),
+    createdAt: z.date(),
+});
+
+export const ActivityFeedResponseSchema = z.object({
+    items: z.array(ActivityItemSchema),
+    meta: z.object({
+        limit: z.number(),
+        offset: z.number(),
+        total: z.number(),
+        hasMore: z.boolean(),
+    }),
+});
+
+export type ActivityFeedResponse = z.infer<typeof ActivityFeedResponseSchema>;

src/modules/activity/activity.service.test.ts

@@ -0,0 +1,28 @@
+import { fetchActivityFeed } from './activity.service';
+import { prisma } from '../../utils/prisma.utils';
+
+describe('Activity Service', () => {
+    beforeAll(async () => {
+        // Clean up and seed minimal test data if needed
+        // In a real environment, we'd use a test database
+    });
+
+    it('should return empty list when no activity exists', async () => {
+        const [items, total] = await fetchActivityFeed({ limit: 10, offset: 0 });
+        expect(Array.isArray(items)).toBe(true);
+        // expect(total).toBe(0); // Depends on DB state
+    });
+
+    it('should filter by creatorId', async () => {
+        const [items] = await fetchActivityFeed({ limit: 10, offset: 0, creatorId: 'non-existent' });
+        expect(items.length).toBe(0);
+    });
+
+    it('should handle pagination', async () => {
+        const [items1] = await fetchActivityFeed({ limit: 1, offset: 0 });
+        const [items2] = await fetchActivityFeed({ limit: 1, offset: 1 });
+        if (items1.length > 0 && items2.length > 0) {
+            expect(items1[0].id).not.toBe(items2[0].id);
+        }
+    });
+});