diff --git a/src/opportunities/opportunities.service.ts b/src/opportunities/opportunities.service.ts
new file mode 100644
index 0000000..ccf7b08
--- /dev/null
+++ b/src/opportunities/opportunities.service.ts
@@ -0,0 +1,92 @@
+import { Injectable, NotFoundException } from '@nestjs/common';
+import { and, desc, eq } from 'drizzle-orm';
+import { db } from '../db/client';
+import { opportunities } from '../db/schema';
+import { AuditService } from '../audit/audit.service';
+import { OutboxService } from '../events/outbox.service';
+import type { AuthenticatedSession } from '../auth/tenant.guard';
+import type { CreateOpportunityDto, UpdateOpportunityDto } from './dto';
+
+@Injectable()
+export class OpportunitiesService {
+  constructor(
+    private readonly outbox: OutboxService,
+    private readonly audit: AuditService,
+  ) {}
+
+  async list(session: AuthenticatedSession) {
+    return db.query.opportunities.findMany({
+      where: eq(opportunities.tenantId, session.tenantId),
+      orderBy: desc(opportunities.createdAt),
+    });
+  }
+
+  async getById(session: AuthenticatedSession, id: string) {
+    const row = await db.query.opportunities.findFirst({
+      where: and(eq(opportunities.id, id), eq(opportunities.tenantId, session.tenantId)),
+    });
+    if (!row) throw new NotFoundException('Opportunity not found');
+    return row;
+  }
+
+  async create(session: AuthenticatedSession, dto: CreateOpportunityDto) {
+    return this.outbox.withTransaction(async (tx) => {
+      const [row] = await tx
+        .insert(opportunities)
+        .values({
+          tenantId: session.tenantId,
+          source: dto.source,
+          entityType: dto.entityType,
+          entityId: dto.entityId,
+          valueRangeMin: dto.valueRangeMin !== undefined ? String(Math.round(dto.valueRangeMin)) : undefined,
+          valueRangeMax: dto.valueRangeMax !== undefined ? String(Math.round(dto.valueRangeMax)) : undefined,
+          probability: dto.probability !== undefined ? String(dto.probability) : undefined,
+          nextAction: dto.nextAction,
+          expiresAt: dto.expiresAt ? new Date(dto.expiresAt) : undefined,
+        })
+        .returning();
+      await this.audit.record(tx, {
+        tenantId: session.tenantId,
+        actorId: session.userId,
+        action: 'opportunity.created',
+        resource: `opportunity:${row.id}`,
+      });
+      await this.outbox.record(tx, {
+        tenantId: session.tenantId,
+        workspaceId: session.workspaceId,
+        actorId: session.userId,
+        eventType: 'opportunity.created',
+        aggregateType: 'opportunity',
+        subjectId: row.id,
+        correlationId: session.correlationId,
+        payload: { source: row.source, entityType: row.entityType },
+      });
+      return row;
+    });
+  }
+
+  async update(session: AuthenticatedSession, id: string, dto: UpdateOpportunityDto) {
+    await this.getById(session, id);
+    return this.outbox.withTransaction(async (tx) => {
+      const [row] = await tx
+        .update(opportunities)
+        .set({
+          ...(dto.probability !== undefined ? { probability: String(dto.probability) } : {}),
+          ...(dto.nextAction !== undefined ? { nextAction: dto.nextAction } : {}),
+          ...(dto.expiresAt !== undefined ? { expiresAt: new Date(dto.expiresAt) } : {}),
+          ...(dto.valueRangeMin !== undefined ? { valueRangeMin: String(Math.round(dto.valueRangeMin)) } : {}),
+          ...(dto.valueRangeMax !== undefined ? { valueRangeMax: String(Math.round(dto.valueRangeMax)) } : {}),
+          updatedAt: new Date(),
+        })
+        .where(and(eq(opportunities.id, id), eq(opportunities.tenantId, session.tenantId)))
+        .returning();
+      await this.audit.record(tx, {
+        tenantId: session.tenantId,
+        actorId: session.userId,
+        action: 'opportunity.updated',
+        resource: `opportunity:${id}`,
+      });
+      return row;
+    });
+  }
+}