diff --git a/CLAUDE.md b/CLAUDE.md
index e13b623..2553b25 100644
--- a/CLAUDE.md
+++ b/CLAUDE.md
@@ -72,7 +72,7 @@ All types use `snake_case` field names matching the server's JSON output exactly
 | `/clients/{id}/ack` | PUT | ACK sequence number. JSON body: `{ "seq": N }`. Returns 204. |
 | `/send` | POST | Transmit CAN frame. JSON body: `pgn`, `src`, `dst`, `prio`, `data`. Returns 202. |
 | `/devices` | GET | Device snapshot. Returns JSON array. |
-| `/values` | GET | Last-seen value per (device, PGN). Returns JSON array grouped by device. |
+| `/values` | GET | Last-seen value per (device, PGN). Query params: `pgn`, `manufacturer`, `instance`, `name` (repeatable). Returns JSON array grouped by device. |
 
 ## Release
 
diff --git a/packages/lplex/README.md b/packages/lplex/README.md
index ae35b5f..01d70bc 100644
--- a/packages/lplex/README.md
+++ b/packages/lplex/README.md
@@ -58,7 +58,7 @@ for (const d of devices) {
 }
 ```
 
-### `client.values(signal?): Promise<DeviceValues[]>`
+### `client.values(filter?, signal?): Promise<DeviceValues[]>`
 
 Returns the last-seen value for each (device, PGN) pair, grouped by device. Useful for getting a snapshot of current bus state without subscribing to SSE.
 
@@ -72,6 +72,15 @@ for (const device of snapshot) {
 }
 ```
 
+Pass a `Filter` to narrow results by PGN and/or device criteria:
+
+```typescript
+const positions = await client.values({
+  pgn: [129025],
+  manufacturer: ["Garmin"],
+});
+```
+
 ### `client.subscribe(filter?, signal?): Promise<AsyncIterable<Event>>`
 
 Opens an ephemeral SSE stream. No session state, no replay. Frames flow until you stop reading or abort.
@@ -326,7 +335,7 @@ interface DeviceValues {
 | `/clients/{id}/ack` | PUT | ACK sequence number. JSON body: `{ "seq": N }`. Returns 204. |
 | `/send` | POST | Transmit CAN frame. JSON body: `pgn`, `src`, `dst`, `prio`, `data`. Returns 202. |
 | `/devices` | GET | Device snapshot. Returns JSON array. |
-| `/values` | GET | Last-seen value per (device, PGN). Returns JSON array grouped by device. |
+| `/values` | GET | Last-seen value per (device, PGN). Query params: `pgn`, `manufacturer`, `instance`, `name` (repeatable). Returns JSON array grouped by device. |
 
 ## License
 
diff --git a/packages/lplex/src/client.ts b/packages/lplex/src/client.ts
index 9f4e75e..5330cf3 100644
--- a/packages/lplex/src/client.ts
+++ b/packages/lplex/src/client.ts
@@ -40,8 +40,10 @@ export class Client {
   }
 
   /** Fetch the last-seen value for each (device, PGN) pair. */
-  async values(signal?: AbortSignal): Promise<DeviceValues[]> {
-    const url = `${this.#baseURL}/values`;
+  async values(filter?: Filter, signal?: AbortSignal): Promise<DeviceValues[]> {
+    let url = `${this.#baseURL}/values`;
+    const qs = filterToQueryString(filter);
+    if (qs) url += `?${qs}`;
     const resp = await this.#fetch(url, { signal });
 
     if (!resp.ok) {
diff --git a/packages/lplex/test/client.test.ts b/packages/lplex/test/client.test.ts
index 20fc5d3..ed8ce1b 100644
--- a/packages/lplex/test/client.test.ts
+++ b/packages/lplex/test/client.test.ts
@@ -102,6 +102,51 @@ describe("Client.values", () => {
     expect(result).toEqual([]);
   });
 
+  it("encodes filter as query params", async () => {
+    let capturedURL = "";
+    const mockFetch = async (url: string | URL | Request) => {
+      capturedURL = String(url);
+      return jsonResponse([]);
+    };
+
+    const client = new Client("http://localhost:8089", {
+      fetch: mockFetch as typeof fetch,
+    });
+    await client.values({ pgn: [129025, 129026], manufacturer: ["Garmin"] });
+
+    const parsed = new URL(capturedURL);
+    expect(parsed.searchParams.getAll("pgn")).toEqual(["129025", "129026"]);
+    expect(parsed.searchParams.getAll("manufacturer")).toEqual(["Garmin"]);
+  });
+
+  it("omits query string when filter is empty", async () => {
+    let capturedURL = "";
+    const mockFetch = async (url: string | URL | Request) => {
+      capturedURL = String(url);
+      return jsonResponse([]);
+    };
+
+    const client = new Client("http://localhost:8089", {
+      fetch: mockFetch as typeof fetch,
+    });
+    await client.values({});
+    expect(capturedURL).toBe("http://localhost:8089/values");
+  });
+
+  it("omits query string when no filter", async () => {
+    let capturedURL = "";
+    const mockFetch = async (url: string | URL | Request) => {
+      capturedURL = String(url);
+      return jsonResponse([]);
+    };
+
+    const client = new Client("http://localhost:8089", {
+      fetch: mockFetch as typeof fetch,
+    });
+    await client.values();
+    expect(capturedURL).toBe("http://localhost:8089/values");
+  });
+
   it("throws HttpError on non-200", async () => {
     const mockFetch = async () => errorResponse(500, "internal error");
     const client = new Client("http://localhost:8089", {