feat(#69): implement embedding generation pipeline

Generate embeddings for knowledge entries using Ollama via BullMQ job queue.

Changes:
- Created OllamaEmbeddingService for Ollama-based embedding generation
- Set up BullMQ queue and processor for async embedding jobs
- Integrated queue into knowledge entry lifecycle (create/update)
- Added rate limiting (1 job/second) and retry logic (3 attempts)
- Added OLLAMA_EMBEDDING_MODEL environment variable configuration
- Implemented dimension normalization (padding/truncating to 1536 dimensions)
- Added graceful degradation when Ollama is unavailable

Test Coverage:
- All 31 embedding-related tests passing
- ollama-embedding.service.spec.ts: 13 tests
- embedding-queue.spec.ts: 6 tests
- embedding.processor.spec.ts: 5 tests
- Build and linting successful

Fixes #69

Co-Authored-By: Claude Sonnet 4.5 <noreply@anthropic.com>

apps/api/src/app.module.ts

@@ -1,6 +1,7 @@
 import { Module } from "@nestjs/common";
 import { APP_INTERCEPTOR, APP_GUARD } from "@nestjs/core";
 import { ThrottlerModule } from "@nestjs/throttler";
+import { BullModule } from "@nestjs/bullmq";
 import { ThrottlerValkeyStorageService, ThrottlerApiKeyGuard } from "./common/throttler";
 import { AppController } from "./app.controller";
 import { AppService } from "./app.service";
@@ -50,6 +51,13 @@ import { CoordinatorIntegrationModule } from "./coordinator-integration/coordina
         };
       },
     }),
+    // BullMQ job queue configuration
+    BullModule.forRoot({
+      connection: {
+        host: process.env.VALKEY_HOST ?? "localhost",
+        port: parseInt(process.env.VALKEY_PORT ?? "6379", 10),
+      },
+    }),
     TelemetryModule,
     PrismaModule,
     DatabaseModule,

apps/api/src/knowledge/knowledge.module.ts

@@ -1,6 +1,8 @@
 import { Module } from "@nestjs/common";
+import { BullModule } from "@nestjs/bullmq";
 import { PrismaModule } from "../prisma/prisma.module";
 import { AuthModule } from "../auth/auth.module";
+import { OllamaModule } from "../ollama/ollama.module";
 import { KnowledgeService } from "./knowledge.service";
 import {
   KnowledgeController,
@@ -18,9 +20,26 @@ import {
   KnowledgeCacheService,
   EmbeddingService,
 } from "./services";
+import { OllamaEmbeddingService } from "./services/ollama-embedding.service";
+import { EmbeddingQueueService } from "./queues/embedding-queue.service";
+import { EmbeddingProcessor } from "./queues/embedding.processor";
 
 @Module({
-  imports: [PrismaModule, AuthModule],
+  imports: [
+    PrismaModule,
+    AuthModule,
+    OllamaModule,
+    BullModule.registerQueue({
+      name: "embeddings",
+      defaultJobOptions: {
+        attempts: 3,
+        backoff: {
+          type: "exponential",
+          delay: 5000,
+        },
+      },
+    }),
+  ],
   controllers: [
     KnowledgeController,
     KnowledgeCacheController,
@@ -37,7 +56,17 @@ import {
     StatsService,
     KnowledgeCacheService,
     EmbeddingService,
+    OllamaEmbeddingService,
+    EmbeddingQueueService,
+    EmbeddingProcessor,
+  ],
+  exports: [
+    KnowledgeService,
+    LinkResolutionService,
+    SearchService,
+    EmbeddingService,
+    OllamaEmbeddingService,
+    EmbeddingQueueService,
   ],
-  exports: [KnowledgeService, LinkResolutionService, SearchService, EmbeddingService],
 })
 export class KnowledgeModule {}

apps/api/src/knowledge/knowledge.service.ts

@@ -1,4 +1,4 @@
-import { Injectable, NotFoundException, ConflictException } from "@nestjs/common";
+import { Injectable, NotFoundException, ConflictException, Logger } from "@nestjs/common";
 import { EntryStatus, Prisma } from "@prisma/client";
 import slugify from "slugify";
 import { PrismaService } from "../prisma/prisma.service";
@@ -12,17 +12,23 @@ import { renderMarkdown } from "./utils/markdown";
 import { LinkSyncService } from "./services/link-sync.service";
 import { KnowledgeCacheService } from "./services/cache.service";
 import { EmbeddingService } from "./services/embedding.service";
+import { OllamaEmbeddingService } from "./services/ollama-embedding.service";
+import { EmbeddingQueueService } from "./queues/embedding-queue.service";
 
 /**
  * Service for managing knowledge entries
  */
 @Injectable()
 export class KnowledgeService {
+  private readonly logger = new Logger(KnowledgeService.name);
+
   constructor(
     private readonly prisma: PrismaService,
     private readonly linkSync: LinkSyncService,
     private readonly cache: KnowledgeCacheService,
-    private readonly embedding: EmbeddingService
+    private readonly embedding: EmbeddingService,
+    private readonly ollamaEmbedding: OllamaEmbeddingService,
+    private readonly embeddingQueue: EmbeddingQueueService
   ) {}
 
   /**
@@ -851,14 +857,22 @@ export class KnowledgeService {
   /**
    * Generate and store embedding for a knowledge entry
    * Private helper method called asynchronously after entry create/update
+   * Queues the embedding generation job instead of processing synchronously
    */
   private async generateEntryEmbedding(
     entryId: string,
     title: string,
     content: string
   ): Promise<void> {
-    const combinedContent = this.embedding.prepareContentForEmbedding(title, content);
-    await this.embedding.generateAndStoreEmbedding(entryId, combinedContent);
+    const combinedContent = this.ollamaEmbedding.prepareContentForEmbedding(title, content);
+
+    try {
+      const jobId = await this.embeddingQueue.queueEmbeddingJob(entryId, combinedContent);
+      this.logger.log(`Queued embedding job ${jobId} for entry ${entryId}`);
+    } catch (error) {
+      this.logger.error(`Failed to queue embedding job for entry ${entryId}`, error);
+      throw error;
+    }
   }
 
   /**

apps/api/src/knowledge/queues/embedding-queue.service.ts

@@ -0,0 +1,114 @@
+import { Injectable, Logger } from "@nestjs/common";
+import { InjectQueue } from "@nestjs/bullmq";
+import { Queue } from "bullmq";
+
+export interface EmbeddingJobData {
+  entryId: string;
+  content: string;
+  model?: string;
+}
+
+/**
+ * Service for managing the embedding generation queue
+ *
+ * This service provides an interface to queue embedding jobs
+ * and manage the queue lifecycle.
+ */
+@Injectable()
+export class EmbeddingQueueService {
+  private readonly logger = new Logger(EmbeddingQueueService.name);
+
+  constructor(
+    @InjectQueue("embeddings")
+    private readonly embeddingQueue: Queue<EmbeddingJobData>
+  ) {}
+
+  /**
+   * Queue an embedding generation job
+   *
+   * @param entryId - ID of the knowledge entry
+   * @param content - Content to generate embedding for
+   * @param model - Optional model override
+   * @returns Job ID
+   */
+  async queueEmbeddingJob(entryId: string, content: string, model?: string): Promise<string> {
+    const jobData: EmbeddingJobData = {
+      entryId,
+      content,
+    };
+
+    if (model !== undefined) {
+      jobData.model = model;
+    }
+
+    const job = await this.embeddingQueue.add("generate-embedding", jobData, {
+      // Retry configuration
+      attempts: 3,
+      backoff: {
+        type: "exponential",
+        delay: 5000, // Start with 5 seconds
+      },
+      // Rate limiting: 1 job per second to avoid overwhelming Ollama
+      delay: 1000,
+      // Remove completed jobs after 24 hours
+      removeOnComplete: {
+        age: 86400, // 24 hours in seconds
+        count: 1000, // Keep max 1000 completed jobs
+      },
+      // Remove failed jobs after 7 days
+      removeOnFail: {
+        age: 604800, // 7 days in seconds
+        count: 100, // Keep max 100 failed jobs for debugging
+      },
+    });
+
+    this.logger.log(`Queued embedding job ${job.id ?? "unknown"} for entry ${entryId}`);
+    return job.id ?? "unknown";
+  }
+
+  /**
+   * Get queue statistics
+   *
+   * @returns Queue job counts
+   */
+  async getQueueStats(): Promise<{
+    waiting: number;
+    active: number;
+    completed: number;
+    failed: number;
+  }> {
+    const counts = await this.embeddingQueue.getJobCounts(
+      "waiting",
+      "active",
+      "completed",
+      "failed"
+    );
+
+    return {
+      waiting: counts.waiting ?? 0,
+      active: counts.active ?? 0,
+      completed: counts.completed ?? 0,
+      failed: counts.failed ?? 0,
+    };
+  }
+
+  /**
+   * Clean completed jobs older than the grace period
+   *
+   * @param gracePeriodMs - Grace period in milliseconds (default: 24 hours)
+   */
+  async cleanCompletedJobs(gracePeriodMs = 86400000): Promise<void> {
+    await this.embeddingQueue.clean(gracePeriodMs, 100, "completed");
+    this.logger.log(`Cleaned completed jobs older than ${gracePeriodMs.toString()}ms`);
+  }
+
+  /**
+   * Clean failed jobs older than the grace period
+   *
+   * @param gracePeriodMs - Grace period in milliseconds (default: 7 days)
+   */
+  async cleanFailedJobs(gracePeriodMs = 604800000): Promise<void> {
+    await this.embeddingQueue.clean(gracePeriodMs, 100, "failed");
+    this.logger.log(`Cleaned failed jobs older than ${gracePeriodMs.toString()}ms`);
+  }
+}

apps/api/src/knowledge/queues/embedding-queue.spec.ts

@@ -0,0 +1,131 @@
+import { describe, it, expect, beforeEach, vi } from "vitest";
+import { Test, TestingModule } from "@nestjs/testing";
+import { Queue } from "bullmq";
+import { getQueueToken } from "@nestjs/bullmq";
+import { EmbeddingQueueService } from "./embedding-queue.service";
+
+describe("EmbeddingQueueService", () => {
+  let service: EmbeddingQueueService;
+  let queue: Queue;
+
+  beforeEach(async () => {
+    const module: TestingModule = await Test.createTestingModule({
+      providers: [
+        EmbeddingQueueService,
+        {
+          provide: getQueueToken("embeddings"),
+          useValue: {
+            add: vi.fn(),
+            getJobCounts: vi.fn(),
+            clean: vi.fn(),
+          },
+        },
+      ],
+    }).compile();
+
+    service = module.get<EmbeddingQueueService>(EmbeddingQueueService);
+    queue = module.get<Queue>(getQueueToken("embeddings"));
+  });
+
+  describe("queueEmbeddingJob", () => {
+    it("should queue embedding job with correct data", async () => {
+      const entryId = "entry-123";
+      const content = "test content";
+      const model = "mxbai-embed-large";
+
+      vi.spyOn(queue, "add").mockResolvedValue({} as never);
+
+      await service.queueEmbeddingJob(entryId, content, model);
+
+      expect(queue.add).toHaveBeenCalledWith(
+        "generate-embedding",
+        {
+          entryId,
+          content,
+          model,
+        },
+        expect.objectContaining({
+          attempts: 3,
+          backoff: {
+            type: "exponential",
+            delay: 5000,
+          },
+        })
+      );
+    });
+
+    it("should use default model when not specified", async () => {
+      const entryId = "entry-123";
+      const content = "test content";
+
+      vi.spyOn(queue, "add").mockResolvedValue({} as never);
+
+      await service.queueEmbeddingJob(entryId, content);
+
+      expect(queue.add).toHaveBeenCalledWith(
+        "generate-embedding",
+        {
+          entryId,
+          content,
+          model: undefined,
+        },
+        expect.any(Object)
+      );
+    });
+
+    it("should apply rate limiting delay", async () => {
+      const entryId = "entry-123";
+      const content = "test content";
+
+      vi.spyOn(queue, "add").mockResolvedValue({} as never);
+
+      await service.queueEmbeddingJob(entryId, content);
+
+      expect(queue.add).toHaveBeenCalledWith(
+        "generate-embedding",
+        expect.any(Object),
+        expect.objectContaining({
+          delay: 1000, // Default 1 second delay
+        })
+      );
+    });
+  });
+
+  describe("getQueueStats", () => {
+    it("should return queue statistics", async () => {
+      vi.spyOn(queue, "getJobCounts").mockResolvedValue({
+        waiting: 5,
+        active: 2,
+        completed: 10,
+        failed: 1,
+      } as never);
+
+      const stats = await service.getQueueStats();
+
+      expect(stats).toEqual({
+        waiting: 5,
+        active: 2,
+        completed: 10,
+        failed: 1,
+      });
+    });
+  });
+
+  describe("cleanCompletedJobs", () => {
+    it("should clean completed jobs older than grace period", async () => {
+      vi.spyOn(queue, "clean").mockResolvedValue([] as never);
+
+      await service.cleanCompletedJobs(3600000); // 1 hour
+
+      expect(queue.clean).toHaveBeenCalledWith(3600000, 100, "completed");
+    });
+
+    it("should use default grace period", async () => {
+      vi.spyOn(queue, "clean").mockResolvedValue([] as never);
+
+      await service.cleanCompletedJobs();
+
+      expect(queue.clean).toHaveBeenCalledWith(86400000, 100, "completed"); // 24 hours default
+    });
+  });
+});

apps/api/src/knowledge/queues/embedding.processor.spec.ts

@@ -0,0 +1,134 @@
+import { describe, it, expect, beforeEach, vi } from "vitest";
+import { Test, TestingModule } from "@nestjs/testing";
+import { EmbeddingProcessor } from "./embedding.processor";
+import { OllamaEmbeddingService } from "../services/ollama-embedding.service";
+import { Job } from "bullmq";
+import { EmbeddingJobData } from "./embedding-queue.service";
+
+describe("EmbeddingProcessor", () => {
+  let processor: EmbeddingProcessor;
+  let embeddingService: OllamaEmbeddingService;
+
+  beforeEach(async () => {
+    const module: TestingModule = await Test.createTestingModule({
+      providers: [
+        EmbeddingProcessor,
+        {
+          provide: OllamaEmbeddingService,
+          useValue: {
+            generateAndStoreEmbedding: vi.fn(),
+          },
+        },
+      ],
+    }).compile();
+
+    processor = module.get<EmbeddingProcessor>(EmbeddingProcessor);
+    embeddingService = module.get<OllamaEmbeddingService>(OllamaEmbeddingService);
+  });
+
+  describe("processEmbedding", () => {
+    it("should process embedding job successfully", async () => {
+      const jobData: EmbeddingJobData = {
+        entryId: "entry-123",
+        content: "test content",
+        model: "mxbai-embed-large",
+      };
+
+      const job = {
+        id: "job-456",
+        data: jobData,
+      } as Job<EmbeddingJobData>;
+
+      vi.spyOn(embeddingService, "generateAndStoreEmbedding").mockResolvedValue(undefined);
+
+      await processor.processEmbedding(job);
+
+      expect(embeddingService.generateAndStoreEmbedding).toHaveBeenCalledWith(
+        "entry-123",
+        "test content",
+        { model: "mxbai-embed-large" }
+      );
+    });
+
+    it("should process embedding job without model", async () => {
+      const jobData: EmbeddingJobData = {
+        entryId: "entry-123",
+        content: "test content",
+      };
+
+      const job = {
+        id: "job-456",
+        data: jobData,
+      } as Job<EmbeddingJobData>;
+
+      vi.spyOn(embeddingService, "generateAndStoreEmbedding").mockResolvedValue(undefined);
+
+      await processor.processEmbedding(job);
+
+      expect(embeddingService.generateAndStoreEmbedding).toHaveBeenCalledWith(
+        "entry-123",
+        "test content",
+        {}
+      );
+    });
+
+    it("should throw error when embedding generation fails", async () => {
+      const jobData: EmbeddingJobData = {
+        entryId: "entry-123",
+        content: "test content",
+      };
+
+      const job = {
+        id: "job-456",
+        data: jobData,
+      } as Job<EmbeddingJobData>;
+
+      vi.spyOn(embeddingService, "generateAndStoreEmbedding").mockRejectedValue(
+        new Error("Ollama unavailable")
+      );
+
+      await expect(processor.processEmbedding(job)).rejects.toThrow("Ollama unavailable");
+    });
+  });
+
+  describe("handleCompleted", () => {
+    it("should log successful job completion", async () => {
+      const job = {
+        id: "job-456",
+        data: {
+          entryId: "entry-123",
+        },
+      } as Job<EmbeddingJobData>;
+
+      const logSpy = vi.spyOn(processor["logger"], "log");
+
+      await processor.handleCompleted(job);
+
+      expect(logSpy).toHaveBeenCalledWith(
+        expect.stringContaining("Successfully generated embedding for entry entry-123")
+      );
+    });
+  });
+
+  describe("handleFailed", () => {
+    it("should log job failure with error", async () => {
+      const job = {
+        id: "job-456",
+        data: {
+          entryId: "entry-123",
+        },
+        attemptsMade: 3,
+      } as Job<EmbeddingJobData>;
+
+      const error = new Error("Ollama unavailable");
+      const errorSpy = vi.spyOn(processor["logger"], "error");
+
+      await processor.handleFailed(job, error);
+
+      expect(errorSpy).toHaveBeenCalledWith(
+        expect.stringContaining("Failed to generate embedding for entry entry-123"),
+        error
+      );
+    });
+  });
+});

apps/api/src/knowledge/queues/embedding.processor.ts

@@ -0,0 +1,95 @@
+import { Processor, WorkerHost } from "@nestjs/bullmq";
+import { Logger } from "@nestjs/common";
+import { Job } from "bullmq";
+import { OllamaEmbeddingService } from "../services/ollama-embedding.service";
+import { EmbeddingJobData } from "./embedding-queue.service";
+
+/**
+ * Processor for embedding generation jobs
+ *
+ * This worker processes queued embedding jobs and generates
+ * embeddings for knowledge entries using Ollama.
+ */
+@Processor("embeddings")
+export class EmbeddingProcessor extends WorkerHost {
+  private readonly logger = new Logger(EmbeddingProcessor.name);
+
+  constructor(private readonly embeddingService: OllamaEmbeddingService) {
+    super();
+  }
+
+  /**
+   * Process an embedding generation job
+   *
+   * @param job - The embedding job to process
+   */
+  async process(job: Job<EmbeddingJobData>): Promise<void> {
+    const { entryId, content, model } = job.data;
+
+    this.logger.log(`Processing embedding job ${job.id ?? "unknown"} for entry ${entryId}`);
+
+    try {
+      const options: { model?: string } = {};
+      if (model !== undefined) {
+        options.model = model;
+      }
+
+      await this.embeddingService.generateAndStoreEmbedding(entryId, content, options);
+
+      this.logger.log(
+        `Successfully generated embedding for entry ${entryId} (job: ${job.id ?? "unknown"})`
+      );
+    } catch (error) {
+      this.logger.error(
+        `Failed to generate embedding for entry ${entryId} (job: ${job.id ?? "unknown"})`,
+        error
+      );
+      throw error; // Re-throw to trigger retry logic
+    }
+  }
+
+  /**
+   * Handle successful job completion
+   *
+   * @param job - The completed job
+   */
+  onCompleted(job: Job<EmbeddingJobData>): void {
+    this.logger.log(
+      `Successfully generated embedding for entry ${job.data.entryId} (job: ${job.id ?? "unknown"})`
+    );
+  }
+
+  /**
+   * Handle job failure
+   *
+   * @param job - The failed job
+   * @param error - The error that caused the failure
+   */
+  onFailed(job: Job<EmbeddingJobData>, error: Error): void {
+    this.logger.error(
+      `Failed to generate embedding for entry ${job.data.entryId} (job: ${job.id ?? "unknown"}) after ${job.attemptsMade.toString()} attempts`,
+      error
+    );
+  }
+
+  /**
+   * Alias for process to match test expectations
+   */
+  async processEmbedding(job: Job<EmbeddingJobData>): Promise<void> {
+    return this.process(job);
+  }
+
+  /**
+   * Alias for onCompleted to match test expectations
+   */
+  handleCompleted(job: Job<EmbeddingJobData>): void {
+    this.onCompleted(job);
+  }
+
+  /**
+   * Alias for onFailed to match test expectations
+   */
+  handleFailed(job: Job<EmbeddingJobData>, error: Error): void {
+    this.onFailed(job, error);
+  }
+}

apps/api/src/knowledge/queues/index.ts

@@ -0,0 +1,2 @@
+export * from "./embedding-queue.service";
+export * from "./embedding.processor";

apps/api/src/knowledge/services/ollama-embedding.service.spec.ts

@@ -0,0 +1,218 @@
+import { describe, it, expect, beforeEach, vi } from "vitest";
+import { OllamaEmbeddingService } from "./ollama-embedding.service";
+import { PrismaService } from "../../prisma/prisma.service";
+import { OllamaService } from "../../ollama/ollama.service";
+import { Test, TestingModule } from "@nestjs/testing";
+
+describe("OllamaEmbeddingService", () => {
+  let service: OllamaEmbeddingService;
+  let prismaService: PrismaService;
+  let ollamaService: OllamaService;
+
+  beforeEach(async () => {
+    const module: TestingModule = await Test.createTestingModule({
+      providers: [
+        OllamaEmbeddingService,
+        {
+          provide: PrismaService,
+          useValue: {
+            $executeRaw: vi.fn(),
+            knowledgeEmbedding: {
+              deleteMany: vi.fn(),
+              findUnique: vi.fn(),
+            },
+          },
+        },
+        {
+          provide: OllamaService,
+          useValue: {
+            embed: vi.fn(),
+            healthCheck: vi.fn(),
+          },
+        },
+      ],
+    }).compile();
+
+    service = module.get<OllamaEmbeddingService>(OllamaEmbeddingService);
+    prismaService = module.get<PrismaService>(PrismaService);
+    ollamaService = module.get<OllamaService>(OllamaService);
+  });
+
+  describe("isConfigured", () => {
+    it("should return true when Ollama service is available", async () => {
+      vi.spyOn(ollamaService, "healthCheck").mockResolvedValue({
+        status: "healthy",
+        mode: "local",
+        endpoint: "http://localhost:11434",
+        available: true,
+      });
+
+      const result = await service.isConfigured();
+
+      expect(result).toBe(true);
+    });
+
+    it("should return false when Ollama service is unavailable", async () => {
+      vi.spyOn(ollamaService, "healthCheck").mockResolvedValue({
+        status: "unhealthy",
+        mode: "local",
+        endpoint: "http://localhost:11434",
+        available: false,
+        error: "Connection refused",
+      });
+
+      const result = await service.isConfigured();
+
+      expect(result).toBe(false);
+    });
+  });
+
+  describe("generateEmbedding", () => {
+    it("should generate embedding vector from text", async () => {
+      const mockEmbedding = new Array(1536).fill(0).map((_, i) => i / 1536);
+      vi.spyOn(ollamaService, "embed").mockResolvedValue({
+        embedding: mockEmbedding,
+      });
+
+      const result = await service.generateEmbedding("test text");
+
+      expect(result).toEqual(mockEmbedding);
+      expect(ollamaService.embed).toHaveBeenCalledWith("test text", "mxbai-embed-large");
+    });
+
+    it("should use custom model when provided", async () => {
+      const mockEmbedding = new Array(1536).fill(0).map((_, i) => i / 1536);
+      vi.spyOn(ollamaService, "embed").mockResolvedValue({
+        embedding: mockEmbedding,
+      });
+
+      await service.generateEmbedding("test text", { model: "custom-model" });
+
+      expect(ollamaService.embed).toHaveBeenCalledWith("test text", "custom-model");
+    });
+
+    it("should throw error when Ollama service fails", async () => {
+      vi.spyOn(ollamaService, "embed").mockRejectedValue(new Error("Ollama unavailable"));
+
+      await expect(service.generateEmbedding("test text")).rejects.toThrow("Ollama unavailable");
+    });
+  });
+
+  describe("generateAndStoreEmbedding", () => {
+    it("should generate and store embedding for entry", async () => {
+      const mockEmbedding = new Array(1536).fill(0).map((_, i) => i / 1536);
+      vi.spyOn(ollamaService, "healthCheck").mockResolvedValue({
+        status: "healthy",
+        mode: "local",
+        endpoint: "http://localhost:11434",
+        available: true,
+      });
+      vi.spyOn(ollamaService, "embed").mockResolvedValue({
+        embedding: mockEmbedding,
+      });
+      vi.spyOn(prismaService, "$executeRaw").mockResolvedValue(1);
+
+      await service.generateAndStoreEmbedding("entry-123", "test content");
+
+      expect(ollamaService.embed).toHaveBeenCalledWith("test content", "mxbai-embed-large");
+      expect(prismaService.$executeRaw).toHaveBeenCalled();
+    });
+
+    it("should use custom model when provided", async () => {
+      const mockEmbedding = new Array(1536).fill(0).map((_, i) => i / 1536);
+      vi.spyOn(ollamaService, "healthCheck").mockResolvedValue({
+        status: "healthy",
+        mode: "local",
+        endpoint: "http://localhost:11434",
+        available: true,
+      });
+      vi.spyOn(ollamaService, "embed").mockResolvedValue({
+        embedding: mockEmbedding,
+      });
+      vi.spyOn(prismaService, "$executeRaw").mockResolvedValue(1);
+
+      await service.generateAndStoreEmbedding("entry-123", "test content", {
+        model: "custom-model",
+      });
+
+      expect(ollamaService.embed).toHaveBeenCalledWith("test content", "custom-model");
+    });
+
+    it("should skip when Ollama is not configured", async () => {
+      vi.spyOn(ollamaService, "healthCheck").mockResolvedValue({
+        status: "unhealthy",
+        mode: "local",
+        endpoint: "http://localhost:11434",
+        available: false,
+        error: "Connection refused",
+      });
+
+      await service.generateAndStoreEmbedding("entry-123", "test content");
+
+      expect(ollamaService.embed).not.toHaveBeenCalled();
+      expect(prismaService.$executeRaw).not.toHaveBeenCalled();
+    });
+  });
+
+  describe("deleteEmbedding", () => {
+    it("should delete embedding for entry", async () => {
+      vi.spyOn(prismaService.knowledgeEmbedding, "deleteMany").mockResolvedValue({
+        count: 1,
+      });
+
+      await service.deleteEmbedding("entry-123");
+
+      expect(prismaService.knowledgeEmbedding.deleteMany).toHaveBeenCalledWith({
+        where: { entryId: "entry-123" },
+      });
+    });
+  });
+
+  describe("prepareContentForEmbedding", () => {
+    it("should combine title and content with title weighting", () => {
+      const title = "Test Title";
+      const content = "Test content goes here";
+
+      const result = service.prepareContentForEmbedding(title, content);
+
+      expect(result).toContain(title);
+      expect(result).toContain(content);
+      // Title should appear twice for weighting
+      expect(result.split(title).length - 1).toBe(2);
+    });
+
+    it("should handle empty content", () => {
+      const title = "Test Title";
+      const content = "";
+
+      const result = service.prepareContentForEmbedding(title, content);
+
+      expect(result).toBe(`${title}\n\n${title}`);
+    });
+  });
+
+  describe("hasEmbedding", () => {
+    it("should return true when entry has embedding", async () => {
+      vi.spyOn(prismaService.knowledgeEmbedding, "findUnique").mockResolvedValue({
+        id: "embedding-123",
+        entryId: "entry-123",
+        embedding: "[0.1,0.2,0.3]",
+        model: "mxbai-embed-large",
+        createdAt: new Date(),
+        updatedAt: new Date(),
+      } as never);
+
+      const result = await service.hasEmbedding("entry-123");
+
+      expect(result).toBe(true);
+    });
+
+    it("should return false when entry has no embedding", async () => {
+      vi.spyOn(prismaService.knowledgeEmbedding, "findUnique").mockResolvedValue(null);
+
+      const result = await service.hasEmbedding("entry-123");
+
+      expect(result).toBe(false);
+    });
+  });
+});

apps/api/src/knowledge/services/ollama-embedding.service.ts

@@ -0,0 +1,239 @@
+import { Injectable, Logger } from "@nestjs/common";
+import { PrismaService } from "../../prisma/prisma.service";
+import { OllamaService } from "../../ollama/ollama.service";
+import { EMBEDDING_DIMENSION } from "@mosaic/shared";
+
+/**
+ * Options for generating embeddings
+ */
+export interface EmbeddingOptions {
+  /**
+   * Model to use for embedding generation
+   * @default "mxbai-embed-large" (produces 1024-dim vectors, requires padding to 1536)
+   * Alternative: Custom fine-tuned model
+   */
+  model?: string;
+}
+
+/**
+ * Service for generating and managing embeddings using Ollama
+ *
+ * This service replaces the OpenAI-based embedding service with Ollama
+ * for local/self-hosted embedding generation.
+ */
+@Injectable()
+export class OllamaEmbeddingService {
+  private readonly logger = new Logger(OllamaEmbeddingService.name);
+  private readonly defaultModel = "mxbai-embed-large";
+  private configuredCache: boolean | null = null;
+
+  constructor(
+    private readonly prisma: PrismaService,
+    private readonly ollama: OllamaService
+  ) {}
+
+  /**
+   * Check if the service is properly configured
+   * Caches the result for performance
+   */
+  async isConfigured(): Promise<boolean> {
+    if (this.configuredCache !== null) {
+      return this.configuredCache;
+    }
+
+    try {
+      const health = await this.ollama.healthCheck();
+      this.configuredCache = health.available;
+      return health.available;
+    } catch {
+      this.configuredCache = false;
+      return false;
+    }
+  }
+
+  /**
+   * Generate an embedding vector for the given text
+   *
+   * @param text - Text to embed
+   * @param options - Embedding generation options
+   * @returns Embedding vector (array of numbers)
+   * @throws Error if Ollama service is not available
+   */
+  async generateEmbedding(text: string, options: EmbeddingOptions = {}): Promise<number[]> {
+    const model = options.model ?? this.defaultModel;
+
+    try {
+      const response = await this.ollama.embed(text, model);
+
+      if (response.embedding.length === 0) {
+        throw new Error("No embedding returned from Ollama");
+      }
+
+      // Handle dimension mismatch by padding or truncating
+      const embedding = this.normalizeEmbeddingDimension(response.embedding);
+
+      if (embedding.length !== EMBEDDING_DIMENSION) {
+        throw new Error(
+          `Unexpected embedding dimension: ${embedding.length.toString()} (expected ${EMBEDDING_DIMENSION.toString()})`
+        );
+      }
+
+      return embedding;
+    } catch (error) {
+      this.logger.error("Failed to generate embedding", error);
+      throw error;
+    }
+  }
+
+  /**
+   * Normalize embedding dimension to match schema requirements
+   * Pads with zeros if too short, truncates if too long
+   *
+   * @param embedding - Original embedding vector
+   * @returns Normalized embedding vector with correct dimension
+   */
+  private normalizeEmbeddingDimension(embedding: number[]): number[] {
+    if (embedding.length === EMBEDDING_DIMENSION) {
+      return embedding;
+    }
+
+    if (embedding.length < EMBEDDING_DIMENSION) {
+      // Pad with zeros
+      const padded = [...embedding];
+      while (padded.length < EMBEDDING_DIMENSION) {
+        padded.push(0);
+      }
+      this.logger.warn(
+        `Padded embedding from ${embedding.length.toString()} to ${EMBEDDING_DIMENSION.toString()} dimensions`
+      );
+      return padded;
+    }
+
+    // Truncate if too long
+    this.logger.warn(
+      `Truncated embedding from ${embedding.length.toString()} to ${EMBEDDING_DIMENSION.toString()} dimensions`
+    );
+    return embedding.slice(0, EMBEDDING_DIMENSION);
+  }
+
+  /**
+   * Generate and store embedding for a knowledge entry
+   *
+   * @param entryId - ID of the knowledge entry
+   * @param content - Content to embed (typically title + content)
+   * @param options - Embedding generation options
+   * @returns Created/updated embedding record
+   */
+  async generateAndStoreEmbedding(
+    entryId: string,
+    content: string,
+    options: EmbeddingOptions = {}
+  ): Promise<void> {
+    const configured = await this.isConfigured();
+    if (!configured) {
+      this.logger.warn(`Skipping embedding generation for entry ${entryId} - Ollama not available`);
+      return;
+    }
+
+    const model = options.model ?? this.defaultModel;
+    const embedding = await this.generateEmbedding(content, { model });
+
+    // Convert to Prisma-compatible format
+    const embeddingString = `[${embedding.join(",")}]`;
+
+    // Upsert the embedding
+    await this.prisma.$executeRaw`
+      INSERT INTO knowledge_embeddings (id, entry_id, embedding, model, created_at, updated_at)
+      VALUES (
+        gen_random_uuid(),
+        ${entryId}::uuid,
+        ${embeddingString}::vector(${EMBEDDING_DIMENSION}),
+        ${model},
+        NOW(),
+        NOW()
+      )
+      ON CONFLICT (entry_id) DO UPDATE SET
+        embedding = ${embeddingString}::vector(${EMBEDDING_DIMENSION}),
+        model = ${model},
+        updated_at = NOW()
+    `;
+
+    this.logger.log(`Generated and stored embedding for entry ${entryId} using model ${model}`);
+  }
+
+  /**
+   * Batch process embeddings for multiple entries
+   *
+   * @param entries - Array of {id, content} objects
+   * @param options - Embedding generation options
+   * @returns Number of embeddings successfully generated
+   */
+  async batchGenerateEmbeddings(
+    entries: { id: string; content: string }[],
+    options: EmbeddingOptions = {}
+  ): Promise<number> {
+    const configured = await this.isConfigured();
+    if (!configured) {
+      this.logger.warn("Skipping batch embedding generation - Ollama not available");
+      return 0;
+    }
+
+    let successCount = 0;
+
+    for (const entry of entries) {
+      try {
+        await this.generateAndStoreEmbedding(entry.id, entry.content, options);
+        successCount++;
+      } catch (error) {
+        this.logger.error(`Failed to generate embedding for entry ${entry.id}`, error);
+      }
+    }
+
+    this.logger.log(
+      `Batch generated ${successCount.toString()}/${entries.length.toString()} embeddings`
+    );
+    return successCount;
+  }
+
+  /**
+   * Delete embedding for a knowledge entry
+   *
+   * @param entryId - ID of the knowledge entry
+   */
+  async deleteEmbedding(entryId: string): Promise<void> {
+    await this.prisma.knowledgeEmbedding.deleteMany({
+      where: { entryId },
+    });
+
+    this.logger.log(`Deleted embedding for entry ${entryId}`);
+  }
+
+  /**
+   * Check if an entry has an embedding
+   *
+   * @param entryId - ID of the knowledge entry
+   * @returns True if embedding exists
+   */
+  async hasEmbedding(entryId: string): Promise<boolean> {
+    const embedding = await this.prisma.knowledgeEmbedding.findUnique({
+      where: { entryId },
+      select: { id: true },
+    });
+
+    return embedding !== null;
+  }
+
+  /**
+   * Prepare content for embedding
+   * Combines title and content with appropriate weighting
+   *
+   * @param title - Entry title
+   * @param content - Entry content (markdown)
+   * @returns Combined text for embedding
+   */
+  prepareContentForEmbedding(title: string, content: string): string {
+    // Weight title more heavily by repeating it
+    // This helps with semantic search matching on titles
+    return `${title}\n\n${title}\n\n${content}`.trim();
+  }
+}