diff --git a/web/src/server/api/root.ts b/web/src/server/api/root.ts
index 972114d..909e3dd 100644
--- a/web/src/server/api/root.ts
+++ b/web/src/server/api/root.ts
@@ -2,6 +2,7 @@ import { exampleRouter } from "./routers/example";
 import { userRouter } from "./routers/user";
 import { billingRouter } from "./routers/billing";
 import { notificationRouter } from "./routers/notification";
+import { darkwatchRouter } from "./routers/darkwatch";
 import { createTRPCRouter } from "./utils";
 
 export const appRouter = createTRPCRouter({
@@ -9,6 +10,7 @@ export const appRouter = createTRPCRouter({
   user: userRouter,
   billing: billingRouter,
   notification: notificationRouter,
+  darkwatch: darkwatchRouter,
 });
 
 export type AppRouter = typeof appRouter;
diff --git a/web/src/server/api/routers/darkwatch.test.ts b/web/src/server/api/routers/darkwatch.test.ts
new file mode 100644
index 0000000..97a2a63
--- /dev/null
+++ b/web/src/server/api/routers/darkwatch.test.ts
@@ -0,0 +1,202 @@
+import { describe, it, expect, vi, beforeEach } from "vitest";
+import { initTRPC, TRPCError } from "@trpc/server";
+import { wrap } from "@typeschema/valibot";
+import {
+  AddWatchlistItemSchema,
+  RemoveWatchlistItemSchema,
+  ExposureFilterSchema,
+  ExposureDetailsSchema,
+  RunScanSchema,
+  ReportFilterSchema,
+} from "../schemas/darkwatch";
+
+vi.mock("~/server/services/darkwatch.service", () => ({
+  getWatchlistItems: vi.fn(),
+  addWatchlistItem: vi.fn(),
+  removeWatchlistItem: vi.fn(),
+  getExposures: vi.fn(),
+  getExposureDetails: vi.fn(),
+  runScan: vi.fn(),
+  getScanStatus: vi.fn(),
+  getReports: vi.fn(),
+}));
+
+import * as darkwatchService from "~/server/services/darkwatch.service";
+
+const mockGetWatchlistItems = vi.mocked(darkwatchService.getWatchlistItems);
+const mockAddWatchlistItem = vi.mocked(darkwatchService.addWatchlistItem);
+const mockRemoveWatchlistItem = vi.mocked(darkwatchService.removeWatchlistItem);
+const mockGetExposures = vi.mocked(darkwatchService.getExposures);
+const mockGetExposureDetails = vi.mocked(darkwatchService.getExposureDetails);
+const mockRunScan = vi.mocked(darkwatchService.runScan);
+const mockGetScanStatus = vi.mocked(darkwatchService.getScanStatus);
+const mockGetReports = vi.mocked(darkwatchService.getReports);
+
+type User = {
+  id: string; email: string; name: string | null; image: string | null;
+  role: string; emailVerified: Date | null; deletedAt: Date | null;
+  stripeCustomerId: string | null;
+  createdAt: Date; updatedAt: Date;
+};
+type Ctx = { db: object; user: User | null; apiKey: string | null };
+
+function createCaller(user: User | null) {
+  const t = initTRPC.context<Ctx>().create();
+  const isAuthed = t.middleware(({ ctx, next }) => {
+    if (!ctx.user) throw new TRPCError({ code: "UNAUTHORIZED" });
+    return next({ ctx: { ...ctx, user: ctx.user } });
+  });
+
+  const router = t.router({
+    getWatchlist: t.procedure.use(isAuthed).query(async ({ ctx }) => {
+      return mockGetWatchlistItems(ctx.user.id);
+    }),
+    addWatchlistItem: t.procedure.use(isAuthed)
+      .input(wrap(AddWatchlistItemSchema))
+      .mutation(async ({ ctx, input }) => {
+        return mockAddWatchlistItem(ctx.user.id, input.type, input.value);
+      }),
+    removeWatchlistItem: t.procedure.use(isAuthed)
+      .input(wrap(RemoveWatchlistItemSchema))
+      .mutation(async ({ ctx, input }) => {
+        return mockRemoveWatchlistItem(ctx.user.id, input.itemId);
+      }),
+    getExposures: t.procedure.use(isAuthed)
+      .input(wrap(ExposureFilterSchema))
+      .query(async ({ ctx, input }) => {
+        return mockGetExposures(ctx.user.id, input);
+      }),
+    getExposureDetails: t.procedure.use(isAuthed)
+      .input(wrap(ExposureDetailsSchema))
+      .query(async ({ ctx, input }) => {
+        return mockGetExposureDetails(ctx.user.id, input.exposureId);
+      }),
+    runScan: t.procedure.use(isAuthed)
+      .input(wrap(RunScanSchema))
+      .mutation(async ({ ctx }) => {
+        return mockRunScan(ctx.user.id);
+      }),
+    getScanStatus: t.procedure.use(isAuthed).query(async ({ ctx }) => {
+      return mockGetScanStatus(ctx.user.id);
+    }),
+    getReports: t.procedure.use(isAuthed)
+      .input(wrap(ReportFilterSchema))
+      .query(async ({ ctx, input }) => {
+        return mockGetReports(ctx.user.id, input);
+      }),
+  });
+
+  const caller = t.createCallerFactory(router);
+  return caller({ db: {} as never, user, apiKey: null });
+}
+
+const baseUser: User = {
+  id: "user-1", email: "a@b.com", name: "Test", image: null,
+  role: "user", emailVerified: null, deletedAt: null,
+  stripeCustomerId: null,
+  createdAt: new Date(), updatedAt: new Date(),
+};
+
+function makeUser(overrides: Partial<User> = {}): User {
+  return { ...baseUser, ...overrides };
+}
+
+beforeEach(() => {
+  vi.clearAllMocks();
+});
+
+describe("darkwatch.getWatchlist", () => {
+  it("returns watchlist items for authenticated user", async () => {
+    const items = [{ id: "w1", type: "email", value: "test@example.com" }];
+    mockGetWatchlistItems.mockResolvedValue(items as never);
+    const api = createCaller(makeUser());
+    expect(await api.getWatchlist()).toEqual(items);
+  });
+
+  it("rejects unauthenticated", async () => {
+    const api = createCaller(null);
+    await expect(api.getWatchlist()).rejects.toThrow(TRPCError);
+  });
+});
+
+describe("darkwatch.addWatchlistItem", () => {
+  it("adds a watchlist item", async () => {
+    const item = { id: "w1", type: "email", value: "test@example.com" };
+    mockAddWatchlistItem.mockResolvedValue(item as never);
+    const api = createCaller(makeUser());
+    const result = await api.addWatchlistItem({ type: "email", value: "test@example.com" });
+    expect(result).toEqual(item);
+  });
+
+  it("rejects invalid type", async () => {
+    const api = createCaller(makeUser());
+    await expect(
+      api.addWatchlistItem({ type: "invalid" as never, value: "test" }),
+    ).rejects.toThrow();
+  });
+});
+
+describe("darkwatch.removeWatchlistItem", () => {
+  it("removes a watchlist item", async () => {
+    mockRemoveWatchlistItem.mockResolvedValue({ id: "w1", isActive: false } as never);
+    const api = createCaller(makeUser());
+    const result = await api.removeWatchlistItem({ itemId: "w1" });
+    expect(result.isActive).toBe(false);
+  });
+});
+
+describe("darkwatch.getExposures", () => {
+  it("returns exposures with pagination", async () => {
+    const data = { items: [], total: 0, page: 1, limit: 20, totalPages: 0 };
+    mockGetExposures.mockResolvedValue(data);
+    const api = createCaller(makeUser());
+    const result = await api.getExposures({ page: 1, limit: 20 });
+    expect(result.total).toBe(0);
+  });
+
+  it("passes severity filter", async () => {
+    const data = { items: [], total: 0, page: 1, limit: 20, totalPages: 0 };
+    mockGetExposures.mockResolvedValue(data);
+    const api = createCaller(makeUser());
+    await api.getExposures({ severity: "critical" });
+    expect(mockGetExposures).toHaveBeenCalledWith("user-1", { severity: "critical", page: 1, limit: 20 });
+  });
+});
+
+describe("darkwatch.getExposureDetails", () => {
+  it("returns exposure details", async () => {
+    const exposure = { id: "e1", identifier: "test@example.com", watchlistItem: null };
+    mockGetExposureDetails.mockResolvedValue(exposure as never);
+    const api = createCaller(makeUser());
+    const result = await api.getExposureDetails({ exposureId: "e1" });
+    expect(result.id).toBe("e1");
+  });
+});
+
+describe("darkwatch.runScan", () => {
+  it("triggers a scan", async () => {
+    mockRunScan.mockResolvedValue({ scanId: "s1" });
+    const api = createCaller(makeUser());
+    const result = await api.runScan({});
+    expect(result.scanId).toBe("s1");
+  });
+});
+
+describe("darkwatch.getScanStatus", () => {
+  it("returns scan status", async () => {
+    mockGetScanStatus.mockResolvedValue({ status: "idle", startedAt: null, completedAt: null, progress: 0, error: null });
+    const api = createCaller(makeUser());
+    const result = await api.getScanStatus();
+    expect(result.status).toBe("idle");
+  });
+});
+
+describe("darkwatch.getReports", () => {
+  it("returns reports", async () => {
+    const data = { items: [], total: 0, page: 1, limit: 20, totalPages: 0 };
+    mockGetReports.mockResolvedValue(data);
+    const api = createCaller(makeUser());
+    const result = await api.getReports({ page: 1, limit: 20 });
+    expect(result.total).toBe(0);
+  });
+});
diff --git a/web/src/server/api/routers/darkwatch.ts b/web/src/server/api/routers/darkwatch.ts
new file mode 100644
index 0000000..169f995
--- /dev/null
+++ b/web/src/server/api/routers/darkwatch.ts
@@ -0,0 +1,57 @@
+import { wrap } from "@typeschema/valibot";
+import { createTRPCRouter, protectedProcedure } from "../utils";
+import {
+  AddWatchlistItemSchema,
+  RemoveWatchlistItemSchema,
+  ExposureFilterSchema,
+  ExposureDetailsSchema,
+  RunScanSchema,
+  ReportFilterSchema,
+} from "../schemas/darkwatch";
+import * as darkwatchService from "~/server/services/darkwatch.service";
+
+export const darkwatchRouter = createTRPCRouter({
+  getWatchlist: protectedProcedure.query(async ({ ctx }) => {
+    return darkwatchService.getWatchlistItems(ctx.user.id);
+  }),
+
+  addWatchlistItem: protectedProcedure
+    .input(wrap(AddWatchlistItemSchema))
+    .mutation(async ({ ctx, input }) => {
+      return darkwatchService.addWatchlistItem(ctx.user.id, input.type, input.value);
+    }),
+
+  removeWatchlistItem: protectedProcedure
+    .input(wrap(RemoveWatchlistItemSchema))
+    .mutation(async ({ ctx, input }) => {
+      return darkwatchService.removeWatchlistItem(ctx.user.id, input.itemId);
+    }),
+
+  getExposures: protectedProcedure
+    .input(wrap(ExposureFilterSchema))
+    .query(async ({ ctx, input }) => {
+      return darkwatchService.getExposures(ctx.user.id, input);
+    }),
+
+  getExposureDetails: protectedProcedure
+    .input(wrap(ExposureDetailsSchema))
+    .query(async ({ ctx, input }) => {
+      return darkwatchService.getExposureDetails(ctx.user.id, input.exposureId);
+    }),
+
+  runScan: protectedProcedure
+    .input(wrap(RunScanSchema))
+    .mutation(async ({ ctx }) => {
+      return darkwatchService.runScan(ctx.user.id);
+    }),
+
+  getScanStatus: protectedProcedure.query(async ({ ctx }) => {
+    return darkwatchService.getScanStatus(ctx.user.id);
+  }),
+
+  getReports: protectedProcedure
+    .input(wrap(ReportFilterSchema))
+    .query(async ({ ctx, input }) => {
+      return darkwatchService.getReports(ctx.user.id, input);
+    }),
+});
diff --git a/web/src/server/api/schemas/darkwatch.ts b/web/src/server/api/schemas/darkwatch.ts
new file mode 100644
index 0000000..fff1736
--- /dev/null
+++ b/web/src/server/api/schemas/darkwatch.ts
@@ -0,0 +1,28 @@
+import { object, string, minLength, optional, number, picklist } from "valibot";
+
+export const AddWatchlistItemSchema = object({
+  type: picklist(["email", "phoneNumber", "ssn", "address", "domain"]),
+  value: string([minLength(1)]),
+});
+
+export const RemoveWatchlistItemSchema = object({
+  itemId: string([minLength(1)]),
+});
+
+export const ExposureFilterSchema = object({
+  severity: optional(picklist(["info", "warning", "critical"])),
+  source: optional(picklist(["hibp", "securityTrails", "censys", "darkWebForum", "shodan", "honeypot"])),
+  page: optional(number(), 1),
+  limit: optional(number(), 20),
+});
+
+export const ExposureDetailsSchema = object({
+  exposureId: string([minLength(1)]),
+});
+
+export const RunScanSchema = object({});
+
+export const ReportFilterSchema = object({
+  page: optional(number(), 1),
+  limit: optional(number(), 20),
+});
diff --git a/web/src/server/services/darkwatch.service.test.ts b/web/src/server/services/darkwatch.service.test.ts
new file mode 100644
index 0000000..16ba194
--- /dev/null
+++ b/web/src/server/services/darkwatch.service.test.ts
@@ -0,0 +1,138 @@
+import { describe, it, expect, vi, beforeEach } from "vitest";
+import { TRPCError } from "@trpc/server";
+
+const mockSelectFromWhereLimit = vi.fn();
+const mockSelectFromWhereOrderByLimitOffset = vi.fn();
+const mockInsertValuesReturning = vi.fn();
+const mockUpdateSetWhereReturning = vi.fn();
+const mockSubFindFirst = vi.fn();
+const mockWhereLimit = vi.fn();
+const mockCountSelectFromWhere = vi.fn();
+
+vi.mock("~/server/db", () => ({
+  db: {
+    query: {
+      subscriptions: {
+        findFirst: mockSubFindFirst,
+      },
+    },
+    select: vi.fn((...args: unknown[]) => {
+      const firstArg = args[0] as { count?: unknown } | undefined;
+      const isCount = args.length > 0 && firstArg?.count;
+
+      if (isCount) {
+        return {
+          from: vi.fn(() => ({
+            where: vi.fn(() => mockCountSelectFromWhere()),
+          })),
+        };
+      }
+
+      return {
+        from: vi.fn(() => ({
+          where: vi.fn(() => ({
+            limit: mockSelectFromWhereLimit,
+            orderBy: vi.fn(() => ({
+              limit: vi.fn(() => ({
+                offset: mockSelectFromWhereOrderByLimitOffset,
+              })),
+            })),
+          })),
+          innerJoin: vi.fn(() => ({
+            where: vi.fn(() => ({
+              limit: vi.fn().mockResolvedValue([]),
+            })),
+          })),
+        })),
+      };
+    }),
+    insert: vi.fn(() => ({
+      values: vi.fn(() => ({
+        returning: mockInsertValuesReturning,
+      })),
+    })),
+    update: vi.fn(() => ({
+      set: vi.fn(() => ({
+        where: vi.fn(() => ({
+          returning: mockUpdateSetWhereReturning,
+        })),
+      })),
+    })),
+  },
+}));
+
+const mockSub = {
+  id: "sub-1",
+  userId: "user-1",
+  tier: "premium" as const,
+  status: "active" as const,
+  stripeId: null as string | null,
+  familyGroupId: null as string | null,
+  currentPeriodStart: new Date(),
+  currentPeriodEnd: new Date(Date.now() + 86400000),
+  cancelAtPeriodEnd: false,
+  createdAt: new Date(),
+  updatedAt: new Date(),
+};
+
+beforeEach(() => {
+  vi.clearAllMocks();
+  mockSelectFromWhereLimit.mockResolvedValue([mockSub]);
+});
+
+describe("checkTierLimits", () => {
+  it("allows premium tier always", async () => {
+    mockSubFindFirst.mockResolvedValue({ ...mockSub, tier: "premium" as const });
+    const { checkTierLimits } = await import("./darkwatch.service");
+    const result = await checkTierLimits("user-1");
+    expect(result.allowed).toBe(true);
+  });
+
+  it("allows basic tier if under limit", async () => {
+    mockSubFindFirst.mockResolvedValue({ ...mockSub, tier: "basic" as const });
+    mockCountSelectFromWhere.mockResolvedValue([{ count: 0 }]);
+    const { checkTierLimits } = await import("./darkwatch.service");
+    const result = await checkTierLimits("user-1");
+    expect(result.allowed).toBe(true);
+  });
+});
+
+describe("addWatchlistItem", () => {
+  it("hashes and deduplicates values", async () => {
+    mockSubFindFirst.mockResolvedValue(mockSub);
+    mockSelectFromWhereLimit
+      .mockResolvedValueOnce([mockSub])
+      .mockResolvedValueOnce([]);
+    mockInsertValuesReturning.mockResolvedValue([{
+      id: "w1", subscriptionId: "sub-1", type: "email", value: "test@example.com",
+      hash: "some-hash", isActive: true,
+      createdAt: new Date(), updatedAt: new Date(),
+    }]);
+    const { addWatchlistItem } = await import("./darkwatch.service");
+    const result = await addWatchlistItem("user-1", "email", "test@example.com");
+    expect(result.type).toBe("email");
+    expect(result.value).toBe("test@example.com");
+  });
+});
+
+describe("removeWatchlistItem", () => {
+  it("throws not found if item does not belong to user", async () => {
+    mockSubFindFirst.mockResolvedValue(mockSub);
+    mockSelectFromWhereLimit.mockResolvedValue([]);
+    const { removeWatchlistItem } = await import("./darkwatch.service");
+    await expect(removeWatchlistItem("user-1", "nonexistent")).rejects.toThrow(TRPCError);
+  });
+});
+
+describe("getExposures", () => {
+  it("returns paginated exposures", async () => {
+    mockSubFindFirst.mockResolvedValue(mockSub);
+    mockCountSelectFromWhere.mockResolvedValue([{ count: 0 }]);
+    mockSelectFromWhereOrderByLimitOffset.mockResolvedValue([]);
+    const { getExposures } = await import("./darkwatch.service");
+    const result = await getExposures("user-1", { page: 1, limit: 10 });
+    expect(result.items).toEqual([]);
+    expect(result.total).toBe(0);
+    expect(result.page).toBe(1);
+  });
+});
diff --git a/web/src/server/services/darkwatch.service.ts b/web/src/server/services/darkwatch.service.ts
new file mode 100644
index 0000000..1c47033
--- /dev/null
+++ b/web/src/server/services/darkwatch.service.ts
@@ -0,0 +1,363 @@
+import { createHash } from "node:crypto";
+import { TRPCError } from "@trpc/server";
+import { eq, and, desc, count, gte, lte, inArray, sql } from "drizzle-orm";
+import { db } from "~/server/db";
+import { watchlistItems, exposures, subscriptions, securityReports } from "~/server/db/schema";
+import { scanHIBP, scanSecurityTrails, scanCensys, scanShodan, scanForums } from "./darkwatch/scan.engine";
+import { processExposure } from "./darkwatch/alert.pipeline";
+import type { ScanResult } from "./darkwatch/scan.engine";
+
+interface ScanState {
+  status: "idle" | "running" | "completed" | "failed";
+  startedAt: Date | null;
+  completedAt: Date | null;
+  totalSources: number;
+  completedSources: number;
+  error: string | null;
+}
+
+const scanStates = new Map<string, ScanState>();
+
+function hashValue(value: string): string {
+  return createHash("sha256").update(value.toLowerCase().trim()).digest("hex");
+}
+
+async function getSubscription(userId: string) {
+  const [sub] = await db
+    .select()
+    .from(subscriptions)
+    .where(and(eq(subscriptions.userId, userId), eq(subscriptions.status, "active")))
+    .limit(1);
+  if (!sub) {
+    throw new TRPCError({ code: "NOT_FOUND", message: "No active subscription found" });
+  }
+  return sub;
+}
+
+export async function getWatchlistItems(userId: string) {
+  const sub = await getSubscription(userId);
+  const items = await db
+    .select()
+    .from(watchlistItems)
+    .where(and(eq(watchlistItems.subscriptionId, sub.id), eq(watchlistItems.isActive, true)))
+    .orderBy(desc(watchlistItems.createdAt));
+  return items;
+}
+
+export async function addWatchlistItem(userId: string, type: string, value: string) {
+  const sub = await getSubscription(userId);
+  const hash = hashValue(value);
+
+  const [existing] = await db
+    .select()
+    .from(watchlistItems)
+    .where(
+      and(
+        eq(watchlistItems.subscriptionId, sub.id),
+        eq(watchlistItems.type, type as "email" | "phoneNumber" | "ssn" | "address" | "domain"),
+        eq(watchlistItems.hash, hash),
+      ),
+    )
+    .limit(1);
+
+  if (existing) {
+    if (existing.isActive) {
+      throw new TRPCError({ code: "CONFLICT", message: "Watchlist item already exists" });
+    }
+    const [reactivated] = await db
+      .update(watchlistItems)
+      .set({ isActive: true, updatedAt: new Date() })
+      .where(eq(watchlistItems.id, existing.id))
+      .returning();
+    return reactivated;
+  }
+
+  const [inserted] = await db
+    .insert(watchlistItems)
+    .values({
+      subscriptionId: sub.id,
+      type: type as "email" | "phoneNumber" | "ssn" | "address" | "domain",
+      value,
+      hash,
+    })
+    .returning();
+  return inserted;
+}
+
+export async function removeWatchlistItem(userId: string, itemId: string) {
+  const sub = await getSubscription(userId);
+  const [item] = await db
+    .select()
+    .from(watchlistItems)
+    .where(and(eq(watchlistItems.id, itemId), eq(watchlistItems.subscriptionId, sub.id)))
+    .limit(1);
+
+  if (!item) {
+    throw new TRPCError({ code: "NOT_FOUND", message: "Watchlist item not found" });
+  }
+
+  const [deleted] = await db
+    .update(watchlistItems)
+    .set({ isActive: false, updatedAt: new Date() })
+    .where(eq(watchlistItems.id, itemId))
+    .returning();
+  return deleted;
+}
+
+export async function getExposures(
+  userId: string,
+  filters?: {
+    severity?: string;
+    source?: string;
+    page?: number;
+    limit?: number;
+  },
+) {
+  const sub = await getSubscription(userId);
+  const page = filters?.page ?? 1;
+  const limit = filters?.limit ?? 20;
+  const offset = (page - 1) * limit;
+
+  const conditions = [eq(exposures.subscriptionId, sub.id)];
+  if (filters?.severity) {
+    conditions.push(eq(exposures.severity, filters.severity as "info" | "warning" | "critical"));
+  }
+  if (filters?.source) {
+    conditions.push(eq(exposures.source, filters.source as "hibp" | "securityTrails" | "censys" | "darkWebForum" | "shodan" | "honeypot"));
+  }
+
+  const [totalResult] = await db
+    .select({ count: count() })
+    .from(exposures)
+    .where(and(...conditions));
+
+  const items = await db
+    .select()
+    .from(exposures)
+    .where(and(...conditions))
+    .orderBy(desc(exposures.detectedAt))
+    .limit(limit)
+    .offset(offset);
+
+  return {
+    items,
+    total: totalResult.count,
+    page,
+    limit,
+    totalPages: Math.ceil(totalResult.count / limit),
+  };
+}
+
+export async function getExposureDetails(userId: string, exposureId: string) {
+  const sub = await getSubscription(userId);
+  const [exposure] = await db
+    .select()
+    .from(exposures)
+    .where(and(eq(exposures.id, exposureId), eq(exposures.subscriptionId, sub.id)))
+    .limit(1);
+
+  if (!exposure) {
+    throw new TRPCError({ code: "NOT_FOUND", message: "Exposure not found" });
+  }
+
+  if (exposure.watchlistItemId) {
+    const [item] = await db
+      .select()
+      .from(watchlistItems)
+      .where(eq(watchlistItems.id, exposure.watchlistItemId))
+      .limit(1);
+    return { ...exposure, watchlistItem: item ?? null };
+  }
+
+  return { ...exposure, watchlistItem: null };
+}
+
+export async function checkTierLimits(userId: string): Promise<{ allowed: boolean; reason?: string }> {
+  const sub = await getSubscription(userId);
+  const tier = sub.tier;
+
+  if (tier === "premium") {
+    return { allowed: true };
+  }
+
+  const maxScans: Record<string, number> = {
+    basic: 1,
+    plus: 4,
+  };
+
+  const maxScanCount = maxScans[tier] ?? 1;
+  const periodStart = tier === "plus"
+    ? new Date(Date.now() - 7 * 24 * 60 * 60 * 1000)
+    : new Date(Date.now() - 30 * 24 * 60 * 60 * 1000);
+
+  const [result] = await db
+    .select({ count: count() })
+    .from(exposures)
+    .where(
+      and(
+        eq(exposures.subscriptionId, sub.id),
+        gte(exposures.detectedAt, periodStart),
+      ),
+    );
+
+  if (result.count >= maxScanCount) {
+    const periodLabel = tier === "plus" ? "week" : "month";
+    return {
+      allowed: false,
+      reason: `Scan limit reached: ${maxScanCount} per ${periodLabel} for ${tier} tier`,
+    };
+  }
+
+  return { allowed: true };
+}
+
+export async function runScan(userId: string): Promise<{ scanId: string }> {
+  const sub = await getSubscription(userId);
+
+  const tierCheck = await checkTierLimits(userId);
+  if (!tierCheck.allowed) {
+    throw new TRPCError({ code: "TOO_MANY_REQUESTS", message: tierCheck.reason });
+  }
+
+  if (scanStates.get(userId)?.status === "running") {
+    throw new TRPCError({ code: "TOO_MANY_REQUESTS", message: "Scan already in progress" });
+  }
+
+  const scanId = crypto.randomUUID();
+  scanStates.set(userId, {
+    status: "running",
+    startedAt: new Date(),
+    completedAt: null,
+    totalSources: 4,
+    completedSources: 0,
+    error: null,
+  });
+
+  const items = await db
+    .select()
+    .from(watchlistItems)
+    .where(and(eq(watchlistItems.subscriptionId, sub.id), eq(watchlistItems.isActive, true)));
+
+  processScan(userId, sub.id, items).catch((err) => {
+    console.error("[darkwatch] Scan failed:", err);
+    const state = scanStates.get(userId);
+    if (state) {
+      state.status = "failed";
+      state.error = err instanceof Error ? err.message : "Unknown error";
+    }
+  });
+
+  return { scanId };
+}
+
+async function processScan(
+  userId: string,
+  subscriptionId: string,
+  items: Array<{ id: string; type: string; value: string }>,
+): Promise<void> {
+  const allResults: ScanResult[] = [];
+
+  for (const item of items) {
+    const sourcePromises: Promise<ScanResult[]>[] = [];
+
+    switch (item.type) {
+      case "email":
+        sourcePromises.push(scanHIBP(item.value));
+        break;
+      case "domain":
+        sourcePromises.push(scanSecurityTrails(item.value));
+        sourcePromises.push(scanCensys(item.value));
+        sourcePromises.push(scanShodan(item.value));
+        break;
+      case "phoneNumber":
+        sourcePromises.push(scanShodan(item.value));
+        sourcePromises.push(scanCensys(item.value));
+        break;
+      default:
+        sourcePromises.push(scanShodan(item.value));
+        break;
+    }
+    sourcePromises.push(scanForums(item.value));
+
+    const results = await Promise.allSettled(sourcePromises);
+    for (const r of results) {
+      if (r.status === "fulfilled") {
+        allResults.push(...r.value.map((sr) => ({ ...sr, watchlistItemId: item.id })));
+      }
+    }
+
+    const state = scanStates.get(userId);
+    if (state) {
+      state.completedSources++;
+    }
+  }
+
+  for (const result of allResults) {
+    try {
+      await processExposure({
+        subscriptionId,
+        watchlistItemId: (result as ScanResult & { watchlistItemId: string }).watchlistItemId,
+        source: result.source,
+        dataType: result.dataType,
+        identifier: result.identifier,
+        identifierHash: result.identifierHash,
+        severity: result.severity,
+        metadata: result.metadata,
+        detectedAt: result.detectedAt,
+      });
+    } catch (err) {
+      console.error("[darkwatch] Failed to process exposure:", err);
+    }
+  }
+
+  const state = scanStates.get(userId);
+  if (state) {
+    state.status = "completed";
+    state.completedAt = new Date();
+  }
+}
+
+export async function getScanStatus(userId: string) {
+  const state = scanStates.get(userId);
+  if (!state) {
+    return { status: "idle" as const, startedAt: null, completedAt: null, progress: 0 };
+  }
+  return {
+    status: state.status,
+    startedAt: state.startedAt,
+    completedAt: state.completedAt,
+    progress: state.totalSources > 0 ? state.completedSources / state.totalSources : 0,
+    error: state.error,
+  };
+}
+
+export async function getReports(
+  userId: string,
+  filters?: { page?: number; limit?: number },
+) {
+  const sub = await getSubscription(userId);
+  const page = filters?.page ?? 1;
+  const limit = filters?.limit ?? 20;
+  const offset = (page - 1) * limit;
+
+  const [totalResult] = await db
+    .select({ count: count() })
+    .from(securityReports)
+    .where(eq(securityReports.subscriptionId, sub.id));
+
+  const items = await db
+    .select()
+    .from(securityReports)
+    .where(eq(securityReports.subscriptionId, sub.id))
+    .orderBy(desc(securityReports.createdAt))
+    .limit(limit)
+    .offset(offset);
+
+  return {
+    items,
+    total: totalResult.count,
+    page,
+    limit,
+    totalPages: Math.ceil(totalResult.count / limit),
+  };
+}
diff --git a/web/src/server/services/darkwatch/alert.pipeline.ts b/web/src/server/services/darkwatch/alert.pipeline.ts
new file mode 100644
index 0000000..766e142
--- /dev/null
+++ b/web/src/server/services/darkwatch/alert.pipeline.ts
@@ -0,0 +1,118 @@
+import { eq, and } from "drizzle-orm";
+import { db } from "~/server/db";
+import { exposures, alerts, subscriptions } from "~/server/db/schema";
+
+export function severityScore(exposure: {
+  source: string;
+  dataType: string;
+}): "info" | "warning" | "critical" {
+  const criticalSources = new Set(["hibp"]);
+  const warningSources = new Set(["shodan", "censys", "darkWebForum"]);
+  const criticalTypes = new Set(["ssn"]);
+  const warningTypes = new Set(["email", "phoneNumber"]);
+
+  if (criticalSources.has(exposure.source) || criticalTypes.has(exposure.dataType)) {
+    return "critical";
+  }
+  if (warningSources.has(exposure.source) || warningTypes.has(exposure.dataType)) {
+    return "warning";
+  }
+  return "info";
+}
+
+export async function processExposure(newExposure: {
+  subscriptionId: string;
+  watchlistItemId?: string | null;
+  source: string;
+  dataType: string;
+  identifier: string;
+  identifierHash: string;
+  severity: string;
+  metadata?: Record<string, unknown> | null;
+  detectedAt: Date;
+}): Promise<{ exposureId: string; alertCreated: boolean }> {
+  const severity = newExposure.severity as "info" | "warning" | "critical";
+
+  const [existing] = await db
+    .select()
+    .from(exposures)
+    .where(
+      and(
+        eq(exposures.identifierHash, newExposure.identifierHash),
+        eq(exposures.source, newExposure.source as "hibp" | "securityTrails" | "censys" | "darkWebForum" | "shodan" | "honeypot"),
+      ),
+    )
+    .limit(1);
+
+  if (existing) {
+    const currentSeverityIdx = ["info", "warning", "critical"].indexOf(existing.severity);
+    const newSeverityIdx = ["info", "warning", "critical"].indexOf(severity);
+    if (newSeverityIdx <= currentSeverityIdx) {
+      return { exposureId: existing.id, alertCreated: false };
+    }
+    const [updated] = await db
+      .update(exposures)
+      .set({
+        severity,
+        metadata: newExposure.metadata ?? existing.metadata,
+        detectedAt: newExposure.detectedAt,
+        updatedAt: new Date(),
+      })
+      .where(eq(exposures.id, existing.id))
+      .returning();
+    await createAlertForExposure(updated, severity);
+    return { exposureId: updated.id, alertCreated: true };
+  }
+
+  const [inserted] = await db
+    .insert(exposures)
+    .values({
+      subscriptionId: newExposure.subscriptionId,
+      watchlistItemId: newExposure.watchlistItemId ?? null,
+      source: newExposure.source as "hibp" | "securityTrails" | "censys" | "darkWebForum" | "shodan" | "honeypot",
+      dataType: newExposure.dataType as "email" | "phoneNumber" | "ssn" | "address" | "domain",
+      identifier: newExposure.identifier,
+      identifierHash: newExposure.identifierHash,
+      severity,
+      metadata: newExposure.metadata ?? null,
+      isFirstTime: true,
+      detectedAt: newExposure.detectedAt,
+    })
+    .returning();
+
+  await createAlertForExposure(inserted, severity);
+  return { exposureId: inserted.id, alertCreated: true };
+}
+
+async function createAlertForExposure(
+  exposure: { id: string; subscriptionId: string; severity: string; dataType: string; source: string; identifier: string },
+  severity: "info" | "warning" | "critical",
+): Promise<void> {
+  const alertSeverityMap: Record<string, "info" | "warning" | "critical"> = {
+    info: "info",
+    warning: "warning",
+    critical: "critical",
+  };
+
+  const title = `${severity === "critical" ? "Critical" : severity === "warning" ? "Warning" : "Info"} exposure detected`;
+  const message = `${exposure.dataType} exposed on ${exposure.source}: ${exposure.identifier}`;
+
+  const [sub] = await db
+    .select()
+    .from(subscriptions)
+    .where(eq(subscriptions.id, exposure.subscriptionId))
+    .limit(1);
+
+  if (!sub) return;
+
+  await db.insert(alerts).values({
+    subscriptionId: exposure.subscriptionId,
+    userId: sub.userId,
+    exposureId: exposure.id,
+    type: "exposure_detected",
+    title,
+    message,
+    severity: alertSeverityMap[severity] ?? "info",
+    channel: ["email", "push"],
+  });
+}
diff --git a/web/src/server/services/darkwatch/scan.engine.test.ts b/web/src/server/services/darkwatch/scan.engine.test.ts
new file mode 100644
index 0000000..76d031c
--- /dev/null
+++ b/web/src/server/services/darkwatch/scan.engine.test.ts
@@ -0,0 +1,24 @@
+import { describe, it, expect } from "vitest";
+import { severityScore } from "./alert.pipeline";
+
+describe("severityScore", () => {
+  it("returns critical for HIBP source", () => {
+    expect(severityScore({ source: "hibp", dataType: "email" })).toBe("critical");
+  });
+
+  it("returns critical for ssn data type", () => {
+    expect(severityScore({ source: "darkWebForum", dataType: "ssn" })).toBe("critical");
+  });
+
+  it("returns warning for shodan source", () => {
+    expect(severityScore({ source: "shodan", dataType: "domain" })).toBe("warning");
+  });
+
+  it("returns warning for email data type", () => {
+    expect(severityScore({ source: "securityTrails", dataType: "email" })).toBe("warning");
+  });
+
+  it("returns info for low-risk combinations", () => {
+    expect(severityScore({ source: "securityTrails", dataType: "domain" })).toBe("info");
+  });
+});
diff --git a/web/src/server/services/darkwatch/scan.engine.ts b/web/src/server/services/darkwatch/scan.engine.ts
new file mode 100644
index 0000000..fb936b9
--- /dev/null
+++ b/web/src/server/services/darkwatch/scan.engine.ts
@@ -0,0 +1,188 @@
+import { createHash } from "node:crypto";
+
+interface ScanResult {
+  source: "hibp" | "securityTrails" | "censys" | "shodan" | "darkWebForum";
+  dataType: "email" | "phoneNumber" | "ssn" | "address" | "domain";
+  identifier: string;
+  identifierHash: string;
+  metadata: Record<string, unknown>;
+  detectedAt: Date;
+  severity: "info" | "warning" | "critical";
+}
+
+interface CircuitState {
+  failures: number;
+  lastFailure: number;
+  isOpen: boolean;
+}
+
+const circuits = new Map<string, CircuitState>();
+const THRESHOLD = 5;
+const RESET_MS = 60_000;
+
+function isCircuitOpen(name: string): boolean {
+  const state = circuits.get(name);
+  if (!state) return false;
+  if (!state.isOpen) return false;
+  if (Date.now() - state.lastFailure > RESET_MS) {
+    circuits.delete(name);
+    return false;
+  }
+  return true;
+}
+
+function recordFailure(name: string): void {
+  const state = circuits.get(name) ?? { failures: 0, lastFailure: 0, isOpen: false };
+  state.failures++;
+  state.lastFailure = Date.now();
+  if (state.failures >= THRESHOLD) {
+    state.isOpen = true;
+  }
+  circuits.set(name, state);
+}
+
+function recordSuccess(name: string): void {
+  circuits.delete(name);
+}
+
+async function fetchWithCircuit(name: string, url: string, headers: Record<string, string>): Promise<Response | null> {
+  if (isCircuitOpen(name)) {
+    console.warn(`[darkwatch] Circuit open for ${name}, skipping`);
+    return null;
+  }
+  try {
+    const res = await fetch(url, { headers, signal: AbortSignal.timeout(10_000) });
+    if (!res.ok) {
+      recordFailure(name);
+      console.warn(`[darkwatch] ${name} returned ${res.status}`);
+      return null;
+    }
+    recordSuccess(name);
+    return res;
+  } catch (err) {
+    recordFailure(name);
+    console.error(`[darkwatch] ${name} error:`, err);
+    return null;
+  }
+}
+
+function hashValue(value: string): string {
+  return createHash("sha256").update(value.toLowerCase().trim()).digest("hex");
+}
+
+export async function scanHIBP(email: string): Promise<ScanResult[]> {
+  const apiKey = process.env.HIBP_API_KEY;
+  if (!apiKey) {
+    console.warn("[darkwatch] HIBP_API_KEY not set, skipping HIBP scan");
+    return [];
+  }
+  const res = await fetchWithCircuit(
+    "hibp",
+    `https://haveibeenpwned.com/api/v3/breachedaccount/${encodeURIComponent(email)}?truncateResponse=false`,
+    { "hibp-api-key": apiKey, "user-agent": "ShieldAI-DarkWatch" },
+  );
+  if (!res) return [];
+  const breaches = await res.json() as Array<{ Name: string; BreachDate: string; DataClasses: string[]; Description: string }>;
+  return breaches.map((b) => ({
+    source: "hibp" as const,
+    dataType: "email" as const,
+    identifier: email,
+    identifierHash: hashValue(email),
+    metadata: { breachName: b.Name, breachDate: b.BreachDate, dataClasses: b.DataClasses, description: b.Description },
+    detectedAt: new Date(b.BreachDate),
+    severity: "critical" as const,
+  }));
+}
+
+export async function scanSecurityTrails(identifier: string): Promise<ScanResult[]> {
+  const apiKey = process.env.SECURITYTRAILS_API_KEY;
+  if (!apiKey) {
+    console.warn("[darkwatch] SECURITYTRAILS_API_KEY not set, skipping");
+    return [];
+  }
+  const domain = identifier.includes("@") ? identifier.split("@")[1] : identifier;
+  const res = await fetchWithCircuit(
+    "securitytrails",
+    `https://api.securitytrails.com/v1/domain/${encodeURIComponent(domain)}/subdomains`,
+    { APIKEY: apiKey },
+  );
+  if (!res) return [];
+  const data = await res.json() as { subdomains: string[] };
+  return (data.subdomains ?? []).slice(0, 20).map((sub) => ({
+    source: "securityTrails" as const,
+    dataType: "domain" as const,
+    identifier: `${sub}.${domain}`,
+    identifierHash: hashValue(`${sub}.${domain}`),
+    metadata: { subdomain: sub, domain },
+    detectedAt: new Date(),
+    severity: "info" as const,
+  }));
+}
+
+export async function scanCensys(query: string): Promise<ScanResult[]> {
+  const apiKey = process.env.CENSYS_API_KEY;
+  if (!apiKey) {
+    console.warn("[darkwatch] CENSYS_API_KEY not set, skipping");
+    return [];
+  }
+  const res = await fetchWithCircuit(
+    "censys",
+    `https://search.censys.io/api/v2/hosts/search?q=${encodeURIComponent(query)}&per_page=10`,
+    { Authorization: `Bearer ${apiKey}` },
+  );
+  if (!res) return [];
+  const data = await res.json() as { result?: { hits?: Array<{ ip: string; services?: Array<{ service_name: string; port: number }> }> } };
+  const hits = data.result?.hits ?? [];
+  return hits.map((h) => ({
+    source: "censys" as const,
+    dataType: "domain" as const,
+    identifier: h.ip,
+    identifierHash: hashValue(h.ip),
+    metadata: { ip: h.ip, services: h.services },
+    detectedAt: new Date(),
+    severity: "warning" as const,
+  }));
+}
+
+export async function scanShodan(query: string): Promise<ScanResult[]> {
+  const apiKey = process.env.SHODAN_API_KEY;
+  if (!apiKey) {
+    console.warn("[darkwatch] SHODAN_API_KEY not set, skipping");
+    return [];
+  }
+  const res = await fetchWithCircuit(
+    "shodan",
+    `https://api.shodan.io/shodan/host/search?key=${apiKey}&query=${encodeURIComponent(query)}&limit=10`,
+    {},
+  );
+  if (!res) return [];
+  const data = await res.json() as { matches?: Array<{ ip_str: string; port: number; org?: string; hostnames?: string[] }> };
+  const matches = data.matches ?? [];
+  return matches.map((m) => ({
+    source: "shodan" as const,
+    dataType: "domain" as const,
+    identifier: m.ip_str,
+    identifierHash: hashValue(m.ip_str),
+    metadata: { ip: m.ip_str, port: m.port, org: m.org, hostnames: m.hostnames },
+    detectedAt: new Date(),
+    severity: "warning" as const,
+  }));
+}
+
+export async function scanForums(identifier: string): Promise<ScanResult[]> {
+  const forumEnabled = process.env.DARKWEB_FORUM_ENABLED;
+  if (!forumEnabled || forumEnabled !== "true") {
+    return [];
+  }
+  return [{
+    source: "darkWebForum" as const,
+    dataType: (identifier.includes("@") ? "email" : "domain") as "email" | "domain",
+    identifier,
+    identifierHash: hashValue(identifier),
+    metadata: { note: "Forum scraping placeholder", identifier },
+    detectedAt: new Date(),
+    severity: "warning" as const,
+  }];
+}
+
+export type { ScanResult };