feat(knowledge): add database schema for Knowledge Module

Implements KNOW-001
- KnowledgeEntry, Version, Link, Tag, Embedding models
- Full indexes and constraints
- Seed data for testing

apps/api/prisma/migrations/20260129220645_add_knowledge_module/migration.sql

@@ -0,0 +1,158 @@
+-- CreateEnum
+CREATE TYPE "EntryStatus" AS ENUM ('DRAFT', 'PUBLISHED', 'ARCHIVED');
+
+-- CreateEnum
+CREATE TYPE "Visibility" AS ENUM ('PRIVATE', 'WORKSPACE', 'PUBLIC');
+
+-- AlterTable
+ALTER TABLE "user_layouts" ADD COLUMN     "metadata" JSONB NOT NULL DEFAULT '{}';
+
+-- CreateTable
+CREATE TABLE "knowledge_entries" (
+    "id" UUID NOT NULL,
+    "workspace_id" UUID NOT NULL,
+    "slug" TEXT NOT NULL,
+    "title" TEXT NOT NULL,
+    "content" TEXT NOT NULL,
+    "content_html" TEXT,
+    "summary" TEXT,
+    "status" "EntryStatus" NOT NULL DEFAULT 'DRAFT',
+    "visibility" "Visibility" NOT NULL DEFAULT 'PRIVATE',
+    "created_at" TIMESTAMPTZ NOT NULL DEFAULT CURRENT_TIMESTAMP,
+    "updated_at" TIMESTAMPTZ NOT NULL,
+    "created_by" UUID NOT NULL,
+    "updated_by" UUID NOT NULL,
+
+    CONSTRAINT "knowledge_entries_pkey" PRIMARY KEY ("id")
+);
+
+-- CreateTable
+CREATE TABLE "knowledge_entry_versions" (
+    "id" UUID NOT NULL,
+    "entry_id" UUID NOT NULL,
+    "version" INTEGER NOT NULL,
+    "title" TEXT NOT NULL,
+    "content" TEXT NOT NULL,
+    "summary" TEXT,
+    "created_at" TIMESTAMPTZ NOT NULL DEFAULT CURRENT_TIMESTAMP,
+    "created_by" UUID NOT NULL,
+    "change_note" TEXT,
+
+    CONSTRAINT "knowledge_entry_versions_pkey" PRIMARY KEY ("id")
+);
+
+-- CreateTable
+CREATE TABLE "knowledge_links" (
+    "id" UUID NOT NULL,
+    "source_id" UUID NOT NULL,
+    "target_id" UUID NOT NULL,
+    "link_text" TEXT NOT NULL,
+    "context" TEXT,
+    "created_at" TIMESTAMPTZ NOT NULL DEFAULT CURRENT_TIMESTAMP,
+
+    CONSTRAINT "knowledge_links_pkey" PRIMARY KEY ("id")
+);
+
+-- CreateTable
+CREATE TABLE "knowledge_tags" (
+    "id" UUID NOT NULL,
+    "workspace_id" UUID NOT NULL,
+    "name" TEXT NOT NULL,
+    "slug" TEXT NOT NULL,
+    "color" TEXT,
+    "description" TEXT,
+
+    CONSTRAINT "knowledge_tags_pkey" PRIMARY KEY ("id")
+);
+
+-- CreateTable
+CREATE TABLE "knowledge_entry_tags" (
+    "entry_id" UUID NOT NULL,
+    "tag_id" UUID NOT NULL,
+
+    CONSTRAINT "knowledge_entry_tags_pkey" PRIMARY KEY ("entry_id","tag_id")
+);
+
+-- CreateTable
+CREATE TABLE "knowledge_embeddings" (
+    "id" UUID NOT NULL,
+    "entry_id" UUID NOT NULL,
+    "embedding" vector(1536) NOT NULL,
+    "model" TEXT NOT NULL,
+    "created_at" TIMESTAMPTZ NOT NULL DEFAULT CURRENT_TIMESTAMP,
+    "updated_at" TIMESTAMPTZ NOT NULL,
+
+    CONSTRAINT "knowledge_embeddings_pkey" PRIMARY KEY ("id")
+);
+
+-- CreateIndex
+CREATE INDEX "knowledge_entries_workspace_id_status_idx" ON "knowledge_entries"("workspace_id", "status");
+
+-- CreateIndex
+CREATE INDEX "knowledge_entries_workspace_id_updated_at_idx" ON "knowledge_entries"("workspace_id", "updated_at");
+
+-- CreateIndex
+CREATE INDEX "knowledge_entries_created_by_idx" ON "knowledge_entries"("created_by");
+
+-- CreateIndex
+CREATE INDEX "knowledge_entries_updated_by_idx" ON "knowledge_entries"("updated_by");
+
+-- CreateIndex
+CREATE UNIQUE INDEX "knowledge_entries_workspace_id_slug_key" ON "knowledge_entries"("workspace_id", "slug");
+
+-- CreateIndex
+CREATE INDEX "knowledge_entry_versions_entry_id_version_idx" ON "knowledge_entry_versions"("entry_id", "version");
+
+-- CreateIndex
+CREATE UNIQUE INDEX "knowledge_entry_versions_entry_id_version_key" ON "knowledge_entry_versions"("entry_id", "version");
+
+-- CreateIndex
+CREATE INDEX "knowledge_links_source_id_idx" ON "knowledge_links"("source_id");
+
+-- CreateIndex
+CREATE INDEX "knowledge_links_target_id_idx" ON "knowledge_links"("target_id");
+
+-- CreateIndex
+CREATE UNIQUE INDEX "knowledge_links_source_id_target_id_key" ON "knowledge_links"("source_id", "target_id");
+
+-- CreateIndex
+CREATE INDEX "knowledge_tags_workspace_id_idx" ON "knowledge_tags"("workspace_id");
+
+-- CreateIndex
+CREATE UNIQUE INDEX "knowledge_tags_workspace_id_slug_key" ON "knowledge_tags"("workspace_id", "slug");
+
+-- CreateIndex
+CREATE INDEX "knowledge_entry_tags_entry_id_idx" ON "knowledge_entry_tags"("entry_id");
+
+-- CreateIndex
+CREATE INDEX "knowledge_entry_tags_tag_id_idx" ON "knowledge_entry_tags"("tag_id");
+
+-- CreateIndex
+CREATE UNIQUE INDEX "knowledge_embeddings_entry_id_key" ON "knowledge_embeddings"("entry_id");
+
+-- CreateIndex
+CREATE INDEX "knowledge_embeddings_entry_id_idx" ON "knowledge_embeddings"("entry_id");
+
+-- AddForeignKey
+ALTER TABLE "knowledge_entries" ADD CONSTRAINT "knowledge_entries_workspace_id_fkey" FOREIGN KEY ("workspace_id") REFERENCES "workspaces"("id") ON DELETE CASCADE ON UPDATE CASCADE;
+
+-- AddForeignKey
+ALTER TABLE "knowledge_entry_versions" ADD CONSTRAINT "knowledge_entry_versions_entry_id_fkey" FOREIGN KEY ("entry_id") REFERENCES "knowledge_entries"("id") ON DELETE CASCADE ON UPDATE CASCADE;
+
+-- AddForeignKey
+ALTER TABLE "knowledge_links" ADD CONSTRAINT "knowledge_links_source_id_fkey" FOREIGN KEY ("source_id") REFERENCES "knowledge_entries"("id") ON DELETE CASCADE ON UPDATE CASCADE;
+
+-- AddForeignKey
+ALTER TABLE "knowledge_links" ADD CONSTRAINT "knowledge_links_target_id_fkey" FOREIGN KEY ("target_id") REFERENCES "knowledge_entries"("id") ON DELETE CASCADE ON UPDATE CASCADE;
+
+-- AddForeignKey
+ALTER TABLE "knowledge_tags" ADD CONSTRAINT "knowledge_tags_workspace_id_fkey" FOREIGN KEY ("workspace_id") REFERENCES "workspaces"("id") ON DELETE CASCADE ON UPDATE CASCADE;
+
+-- AddForeignKey
+ALTER TABLE "knowledge_entry_tags" ADD CONSTRAINT "knowledge_entry_tags_entry_id_fkey" FOREIGN KEY ("entry_id") REFERENCES "knowledge_entries"("id") ON DELETE CASCADE ON UPDATE CASCADE;
+
+-- AddForeignKey
+ALTER TABLE "knowledge_entry_tags" ADD CONSTRAINT "knowledge_entry_tags_tag_id_fkey" FOREIGN KEY ("tag_id") REFERENCES "knowledge_tags"("id") ON DELETE CASCADE ON UPDATE CASCADE;
+
+-- AddForeignKey
+ALTER TABLE "knowledge_embeddings" ADD CONSTRAINT "knowledge_embeddings_entry_id_fkey" FOREIGN KEY ("entry_id") REFERENCES "knowledge_entries"("id") ON DELETE CASCADE ON UPDATE CASCADE;

apps/api/prisma/schema.prisma

@@ -96,6 +96,18 @@ enum AgentStatus {
   TERMINATED
 }
 
+enum EntryStatus {
+  DRAFT
+  PUBLISHED
+  ARCHIVED
+}
+
+enum Visibility {
+  PRIVATE
+  WORKSPACE
+  PUBLIC
+}
+
 // ============================================
 // MODELS
 // ============================================
@@ -151,6 +163,8 @@ model Workspace {
   agents             Agent[]
   agentSessions      AgentSession[]
   userLayouts        UserLayout[]
+  knowledgeEntries   KnowledgeEntry[]
+  knowledgeTags      KnowledgeTag[]
 
   @@index([ownerId])
   @@map("workspaces")
@@ -605,3 +619,131 @@ model Verification {
   @@index([identifier])
   @@map("verifications")
 }
+
+// ============================================
+// KNOWLEDGE MODULE
+// ============================================
+
+model KnowledgeEntry {
+  id          String      @id @default(uuid()) @db.Uuid
+  workspaceId String      @map("workspace_id") @db.Uuid
+  workspace   Workspace   @relation(fields: [workspaceId], references: [id], onDelete: Cascade)
+
+  // Identity
+  slug        String
+  title       String
+  
+  // Content
+  content     String      @db.Text
+  contentHtml String?     @map("content_html") @db.Text
+  summary     String?
+  
+  // Status
+  status      EntryStatus @default(DRAFT)
+  visibility  Visibility  @default(PRIVATE)
+  
+  // Audit
+  createdAt   DateTime    @default(now()) @map("created_at") @db.Timestamptz
+  updatedAt   DateTime    @updatedAt @map("updated_at") @db.Timestamptz
+  createdBy   String      @map("created_by") @db.Uuid
+  updatedBy   String      @map("updated_by") @db.Uuid
+  
+  // Relations
+  tags          KnowledgeEntryTag[]
+  outgoingLinks KnowledgeLink[]     @relation("SourceEntry")
+  incomingLinks KnowledgeLink[]     @relation("TargetEntry")
+  versions      KnowledgeEntryVersion[]
+  embedding     KnowledgeEmbedding?
+  
+  @@unique([workspaceId, slug])
+  @@index([workspaceId, status])
+  @@index([workspaceId, updatedAt])
+  @@index([createdBy])
+  @@index([updatedBy])
+  @@map("knowledge_entries")
+}
+
+model KnowledgeEntryVersion {
+  id         String         @id @default(uuid()) @db.Uuid
+  entryId    String         @map("entry_id") @db.Uuid
+  entry      KnowledgeEntry @relation(fields: [entryId], references: [id], onDelete: Cascade)
+  
+  version    Int
+  title      String
+  content    String         @db.Text
+  summary    String?
+  
+  createdAt  DateTime       @default(now()) @map("created_at") @db.Timestamptz
+  createdBy  String         @map("created_by") @db.Uuid
+  changeNote String?        @map("change_note")
+  
+  @@unique([entryId, version])
+  @@index([entryId, version])
+  @@map("knowledge_entry_versions")
+}
+
+model KnowledgeLink {
+  id        String         @id @default(uuid()) @db.Uuid
+  
+  sourceId  String         @map("source_id") @db.Uuid
+  source    KnowledgeEntry @relation("SourceEntry", fields: [sourceId], references: [id], onDelete: Cascade)
+  
+  targetId  String         @map("target_id") @db.Uuid
+  target    KnowledgeEntry @relation("TargetEntry", fields: [targetId], references: [id], onDelete: Cascade)
+  
+  // Link metadata
+  linkText  String         @map("link_text")
+  context   String?
+  
+  createdAt DateTime       @default(now()) @map("created_at") @db.Timestamptz
+  
+  @@unique([sourceId, targetId])
+  @@index([sourceId])
+  @@index([targetId])
+  @@map("knowledge_links")
+}
+
+model KnowledgeTag {
+  id          String @id @default(uuid()) @db.Uuid
+  workspaceId String @map("workspace_id") @db.Uuid
+  workspace   Workspace @relation(fields: [workspaceId], references: [id], onDelete: Cascade)
+  
+  name        String
+  slug        String
+  color       String?
+  description String?
+  
+  entries     KnowledgeEntryTag[]
+  
+  @@unique([workspaceId, slug])
+  @@index([workspaceId])
+  @@map("knowledge_tags")
+}
+
+model KnowledgeEntryTag {
+  entryId String         @map("entry_id") @db.Uuid
+  entry   KnowledgeEntry @relation(fields: [entryId], references: [id], onDelete: Cascade)
+  
+  tagId   String         @map("tag_id") @db.Uuid
+  tag     KnowledgeTag   @relation(fields: [tagId], references: [id], onDelete: Cascade)
+  
+  @@id([entryId, tagId])
+  @@index([entryId])
+  @@index([tagId])
+  @@map("knowledge_entry_tags")
+}
+
+model KnowledgeEmbedding {
+  id        String         @id @default(uuid()) @db.Uuid
+  entryId   String         @unique @map("entry_id") @db.Uuid
+  entry     KnowledgeEntry @relation(fields: [entryId], references: [id], onDelete: Cascade)
+  
+  embedding Unsupported("vector(1536)")
+  model     String
+  
+  createdAt DateTime       @default(now()) @map("created_at") @db.Timestamptz
+  updatedAt DateTime       @updatedAt @map("updated_at") @db.Timestamptz
+  
+  @@index([entryId])
+  @@map("knowledge_embeddings")
+}

apps/api/prisma/seed.ts

@@ -4,6 +4,8 @@ import {
   TaskPriority,
   ProjectStatus,
   WorkspaceMemberRole,
+  EntryStatus,
+  Visibility,
 } from "@prisma/client";
 
 const prisma = new PrismaClient();
@@ -145,6 +147,309 @@ async function main() {
     });
 
     console.log("Created sample event");
+
+    // ============================================
+    // KNOWLEDGE MODULE SEED DATA
+    // ============================================
+
+    // Delete existing knowledge data
+    await tx.knowledgeEmbedding.deleteMany({ where: { entry: { workspaceId: workspace.id } } });
+    await tx.knowledgeEntryTag.deleteMany({ where: { entry: { workspaceId: workspace.id } } });
+    await tx.knowledgeLink.deleteMany({ where: { source: { workspaceId: workspace.id } } });
+    await tx.knowledgeEntryVersion.deleteMany({ where: { entry: { workspaceId: workspace.id } } });
+    await tx.knowledgeEntry.deleteMany({ where: { workspaceId: workspace.id } });
+    await tx.knowledgeTag.deleteMany({ where: { workspaceId: workspace.id } });
+
+    // Create knowledge tags
+    const tags = await Promise.all([
+      tx.knowledgeTag.create({
+        data: {
+          workspaceId: workspace.id,
+          name: "Architecture",
+          slug: "architecture",
+          color: "#3B82F6",
+          description: "System architecture and design decisions",
+        },
+      }),
+      tx.knowledgeTag.create({
+        data: {
+          workspaceId: workspace.id,
+          name: "Development",
+          slug: "development",
+          color: "#10B981",
+          description: "Development practices and guidelines",
+        },
+      }),
+      tx.knowledgeTag.create({
+        data: {
+          workspaceId: workspace.id,
+          name: "Getting Started",
+          slug: "getting-started",
+          color: "#F59E0B",
+          description: "Onboarding and setup guides",
+        },
+      }),
+    ]);
+
+    console.log(`Created ${tags.length} knowledge tags`);
+
+    // Create knowledge entries
+    const entries = [
+      {
+        slug: "welcome",
+        title: "Welcome to Mosaic Stack Knowledge Base",
+        content: `# Welcome to Mosaic Stack
+
+This is the knowledge base for the Mosaic Stack project. Here you'll find:
+
+- **[[architecture-overview]]** - High-level system architecture
+- **[[development-setup]]** - Getting started with development
+- **[[database-schema]]** - Database design and conventions
+
+## About This Knowledge Base
+
+The Knowledge Module provides:
+- Wiki-style linking between entries
+- Full-text and semantic search
+- Version history and change tracking
+- Tag-based organization
+
+Start exploring by following the links above!`,
+        summary: "Introduction to the Mosaic Stack knowledge base and navigation guide",
+        status: EntryStatus.PUBLISHED,
+        visibility: Visibility.WORKSPACE,
+        tags: ["getting-started"],
+      },
+      {
+        slug: "architecture-overview",
+        title: "Architecture Overview",
+        content: `# Architecture Overview
+
+The Mosaic Stack is built on a modern, scalable architecture:
+
+## Stack Components
+
+- **Frontend**: Next.js 15+ with React 19
+- **Backend**: NestJS with Prisma ORM
+- **Database**: PostgreSQL 17 with pgvector
+- **Cache**: Valkey (Redis fork)
+
+## Key Modules
+
+1. **Task Management** - See [[development-setup]] for local setup
+2. **Event Calendar** - Integrated scheduling
+3. **Knowledge Base** - This module! See [[database-schema]]
+4. **Agent Orchestration** - AI agent coordination
+
+The database schema is documented in [[database-schema]].`,
+        summary: "High-level overview of Mosaic Stack architecture and components",
+        status: EntryStatus.PUBLISHED,
+        visibility: Visibility.WORKSPACE,
+        tags: ["architecture"],
+      },
+      {
+        slug: "development-setup",
+        title: "Development Setup Guide",
+        content: `# Development Setup Guide
+
+## Prerequisites
+
+- Node.js 22+
+- PostgreSQL 17
+- pnpm 9+
+
+## Quick Start
+
+\`\`\`bash
+# Clone the repository
+git clone https://git.mosaicstack.dev/mosaic/stack.git
+
+# Install dependencies
+pnpm install
+
+# Set up database
+cd apps/api
+pnpm prisma migrate dev
+pnpm prisma:seed
+
+# Start development servers
+pnpm dev
+\`\`\`
+
+## Architecture
+
+Before diving in, review the [[architecture-overview]] to understand the system design.
+
+## Database
+
+The database schema is documented in [[database-schema]]. All models use Prisma ORM.
+
+## Next Steps
+
+1. Read the [[architecture-overview]]
+2. Explore the codebase
+3. Check out the [[database-schema]] documentation`,
+        summary: "Step-by-step guide to setting up the Mosaic Stack development environment",
+        status: EntryStatus.PUBLISHED,
+        visibility: Visibility.WORKSPACE,
+        tags: ["development", "getting-started"],
+      },
+      {
+        slug: "database-schema",
+        title: "Database Schema Documentation",
+        content: `# Database Schema Documentation
+
+## Overview
+
+Mosaic Stack uses PostgreSQL 17 with Prisma ORM. See [[architecture-overview]] for context.
+
+## Key Conventions
+
+- All IDs are UUIDs
+- Timestamps use \`@db.Timestamptz\` (timezone-aware)
+- Soft deletes via status fields (e.g., ARCHIVED)
+- Relations enforce cascade deletes for data integrity
+
+## Core Models
+
+### Task Management
+- \`Task\` - Individual work items
+- \`Project\` - Task containers
+- \`Domain\` - High-level categorization
+
+### Knowledge Module
+- \`KnowledgeEntry\` - Wiki pages
+- \`KnowledgeLink\` - Page connections
+- \`KnowledgeTag\` - Categorization
+- \`KnowledgeEmbedding\` - Semantic search (pgvector)
+
+### Agent System
+- \`Agent\` - AI agent instances
+- \`AgentSession\` - Conversation sessions
+
+## Migrations
+
+Migrations are managed via Prisma:
+
+\`\`\`bash
+# Create migration
+pnpm prisma migrate dev --name my_migration
+
+# Apply in production
+pnpm prisma migrate deploy
+\`\`\`
+
+For setup instructions, see [[development-setup]].`,
+        summary: "Comprehensive documentation of the Mosaic Stack database schema and Prisma conventions",
+        status: EntryStatus.PUBLISHED,
+        visibility: Visibility.WORKSPACE,
+        tags: ["architecture", "development"],
+      },
+      {
+        slug: "future-ideas",
+        title: "Future Ideas and Roadmap",
+        content: `# Future Ideas and Roadmap
+
+## Planned Features
+
+- Real-time collaboration (CRDT)
+- Advanced graph visualizations
+- AI-powered summarization
+- Mobile app
+
+## Research Areas
+
+- Vector search optimization
+- Knowledge graph algorithms
+- Agent memory systems
+
+This is a draft document. See [[architecture-overview]] for current state.`,
+        summary: "Brainstorming document for future features and research directions",
+        status: EntryStatus.DRAFT,
+        visibility: Visibility.PRIVATE,
+        tags: [],
+      },
+    ];
+
+    // Create entries and track them for linking
+    const createdEntries = new Map<string, any>();
+    
+    for (const entryData of entries) {
+      const entry = await tx.knowledgeEntry.create({
+        data: {
+          workspaceId: workspace.id,
+          slug: entryData.slug,
+          title: entryData.title,
+          content: entryData.content,
+          summary: entryData.summary,
+          status: entryData.status,
+          visibility: entryData.visibility,
+          createdBy: user.id,
+          updatedBy: user.id,
+        },
+      });
+      
+      createdEntries.set(entryData.slug, entry);
+
+      // Create initial version
+      await tx.knowledgeEntryVersion.create({
+        data: {
+          entryId: entry.id,
+          version: 1,
+          title: entry.title,
+          content: entry.content,
+          summary: entry.summary,
+          createdBy: user.id,
+          changeNote: "Initial version",
+        },
+      });
+
+      // Add tags
+      for (const tagSlug of entryData.tags) {
+        const tag = tags.find(t => t.slug === tagSlug);
+        if (tag) {
+          await tx.knowledgeEntryTag.create({
+            data: {
+              entryId: entry.id,
+              tagId: tag.id,
+            },
+          });
+        }
+      }
+    }
+
+    console.log(`Created ${entries.length} knowledge entries`);
+
+    // Create wiki-links between entries
+    const links = [
+      { source: "welcome", target: "architecture-overview", text: "architecture-overview" },
+      { source: "welcome", target: "development-setup", text: "development-setup" },
+      { source: "welcome", target: "database-schema", text: "database-schema" },
+      { source: "architecture-overview", target: "development-setup", text: "development-setup" },
+      { source: "architecture-overview", target: "database-schema", text: "database-schema" },
+      { source: "development-setup", target: "architecture-overview", text: "architecture-overview" },
+      { source: "development-setup", target: "database-schema", text: "database-schema" },
+      { source: "database-schema", target: "architecture-overview", text: "architecture-overview" },
+      { source: "database-schema", target: "development-setup", text: "development-setup" },
+      { source: "future-ideas", target: "architecture-overview", text: "architecture-overview" },
+    ];
+
+    for (const link of links) {
+      const sourceEntry = createdEntries.get(link.source);
+      const targetEntry = createdEntries.get(link.target);
+      
+      if (sourceEntry && targetEntry) {
+        await tx.knowledgeLink.create({
+          data: {
+            sourceId: sourceEntry.id,
+            targetId: targetEntry.id,
+            linkText: link.text,
+          },
+        });
+      }
+    }
+
+    console.log(`Created ${links.length} knowledge links`);
   });
   console.log("Seeding completed successfully!");
 }