diff --git a/src/lib/anchorsApi.test.ts b/src/lib/anchorsApi.test.ts
index 3815d89..5138a2e 100644
--- a/src/lib/anchorsApi.test.ts
+++ b/src/lib/anchorsApi.test.ts
@@ -16,6 +16,37 @@ function mockFetch(status: number, body: unknown) {
   });
 }
 
+/**
+ * Builds a `fetch` mock that emulates real fetch's cancellation behaviour: it
+ * captures the `AbortSignal` handed to the outgoing request and, like the real
+ * `fetch`, rejects with an `AbortError` `DOMException` when that signal aborts.
+ *
+ * `apiRequest` composes the caller's signal with an internal timeout controller
+ * (see `composeSignals` in `api.ts`), so the object reaching `fetch` is a
+ * *derived* signal rather than the caller's signal itself. Asserting that an
+ * abort of the caller's signal propagates to the outgoing request is the
+ * meaningful, implementation-agnostic way to verify signal forwarding — and it
+ * is exactly the regression (a request no longer aborting on unmount/reload)
+ * that this coverage is meant to catch.
+ */
+function mockAbortableFetch() {
+  return vi.fn().mockImplementation((_url: string, init?: RequestInit) => {
+    const signal = init?.signal;
+    return new Promise<Response>((_resolve, reject) => {
+      if (signal?.aborted) {
+        reject(new DOMException("The operation was aborted.", "AbortError"));
+        return;
+      }
+      signal?.addEventListener(
+        "abort",
+        () =>
+          reject(new DOMException("The operation was aborted.", "AbortError")),
+        { once: true },
+      );
+    });
+  });
+}
+
 afterEach(() => {
   vi.unstubAllGlobals();
 });
@@ -25,9 +56,7 @@ describe("anchorsApi", () => {
     vi.stubGlobal(
       "fetch",
       mockFetch(200, {
-        anchors: [
-          { id: "a", name: "A", registeredAt: "", active: true },
-        ],
+        anchors: [{ id: "a", name: "A", registeredAt: "", active: true }],
       }),
     );
 
@@ -50,6 +79,48 @@ describe("anchorsApi", () => {
     expect(fn.mock.calls[0][0]).toContain("/api/v1/anchors/a");
   });
 
+  // `registerAnchor` and `deregisterAnchor` do not accept an AbortSignal, so
+  // only `fetchAnchors` and `fetchAnchor` need signal-forwarding coverage here.
+  describe("abort signal forwarding", () => {
+    it("fetchAnchors forwards the abort signal to the outgoing fetch call", async () => {
+      const fn = mockAbortableFetch();
+      vi.stubGlobal("fetch", fn);
+      const controller = new AbortController();
+
+      const promise = fetchAnchors(controller.signal);
+
+      // The request reached `fetch` with an AbortSignal attached.
+      expect(fn).toHaveBeenCalledTimes(1);
+      const fetchSignal = fn.mock.calls[0][1].signal as AbortSignal;
+      expect(fetchSignal).toBeInstanceOf(AbortSignal);
+      expect(fetchSignal.aborted).toBe(false);
+
+      // Aborting the caller's signal propagates to the outgoing request and
+      // cancels it with an AbortError.
+      controller.abort();
+      expect(fetchSignal.aborted).toBe(true);
+      await expect(promise).rejects.toMatchObject({ name: "AbortError" });
+    });
+
+    it("fetchAnchor forwards the abort signal to the outgoing fetch call", async () => {
+      const fn = mockAbortableFetch();
+      vi.stubGlobal("fetch", fn);
+      const controller = new AbortController();
+
+      const promise = fetchAnchor("a", controller.signal);
+
+      expect(fn).toHaveBeenCalledTimes(1);
+      expect(fn.mock.calls[0][0]).toContain("/api/v1/anchors/a");
+      const fetchSignal = fn.mock.calls[0][1].signal as AbortSignal;
+      expect(fetchSignal).toBeInstanceOf(AbortSignal);
+      expect(fetchSignal.aborted).toBe(false);
+
+      controller.abort();
+      expect(fetchSignal.aborted).toBe(true);
+      await expect(promise).rejects.toMatchObject({ name: "AbortError" });
+    });
+  });
+
   it("surfaces a not-found error for an unknown anchor id", async () => {
     vi.stubGlobal(
       "fetch",
diff --git a/src/lib/metricsApi.test.ts b/src/lib/metricsApi.test.ts
index a83e1ff..ecffdfe 100644
--- a/src/lib/metricsApi.test.ts
+++ b/src/lib/metricsApi.test.ts
@@ -11,6 +11,38 @@ function mockFetch(status: number, body: unknown) {
   });
 }
 
+/**
+ * Builds a `fetch` mock that emulates real fetch's cancellation behaviour.
+ *
+ * The mock captures the `AbortSignal` handed to the outgoing request and, like
+ * the real `fetch`, rejects with an `AbortError` `DOMException` when that signal
+ * is aborted. This lets a test inspect the exact signal that reached `fetch` and
+ * prove that aborting the caller's signal actually cancels the request.
+ *
+ * Note: `apiRequest` composes the caller's signal with an internal timeout
+ * controller (see `composeSignals` in `api.ts`), so the object reaching `fetch`
+ * is a *derived* signal rather than the caller's signal itself. Asserting that
+ * an abort of the caller's signal propagates to the outgoing request is the
+ * meaningful, implementation-agnostic way to verify signal forwarding.
+ */
+function mockAbortableFetch() {
+  return vi.fn().mockImplementation((_url: string, init?: RequestInit) => {
+    const signal = init?.signal;
+    return new Promise<Response>((_resolve, reject) => {
+      if (signal?.aborted) {
+        reject(new DOMException("The operation was aborted.", "AbortError"));
+        return;
+      }
+      signal?.addEventListener(
+        "abort",
+        () =>
+          reject(new DOMException("The operation was aborted.", "AbortError")),
+        { once: true },
+      );
+    });
+  });
+}
+
 afterEach(() => {
   vi.unstubAllGlobals();
 });
@@ -33,19 +65,23 @@ describe("metricsApi", () => {
   });
 
   it("passes the abort signal through", async () => {
-    const fn = mockFetch(200, {
-      anchors: 0,
-      activeAnchors: 0,
-      pools: 0,
-      totalLiquidity: 0,
-      settlements: 0,
-      pendingSettlements: 0,
-    });
+    const fn = mockAbortableFetch();
     vi.stubGlobal("fetch", fn);
     const controller = new AbortController();
 
-    await fetchMetrics(controller.signal);
-    expect(fn.mock.calls[0][1].signal).toBe(controller.signal);
+    const promise = fetchMetrics(controller.signal);
+
+    // The request reached `fetch` with an AbortSignal attached.
+    expect(fn).toHaveBeenCalledTimes(1);
+    const fetchSignal = fn.mock.calls[0][1].signal as AbortSignal;
+    expect(fetchSignal).toBeInstanceOf(AbortSignal);
+    expect(fetchSignal.aborted).toBe(false);
+
+    // Aborting the caller's signal propagates to the outgoing request's signal
+    // and cancels the in-flight request with an AbortError.
+    controller.abort();
+    expect(fetchSignal.aborted).toBe(true);
+    await expect(promise).rejects.toMatchObject({ name: "AbortError" });
   });
 
   it("propagates API error status, code, and message", async () => {
diff --git a/src/lib/settlementsApi.test.ts b/src/lib/settlementsApi.test.ts
index dcd9947..fedb418 100644
--- a/src/lib/settlementsApi.test.ts
+++ b/src/lib/settlementsApi.test.ts
@@ -2,6 +2,7 @@ import { describe, it, expect, vi, afterEach } from "vitest";
 import {
   fetchSettlements,
   fetchSettlement,
+  exportSettlementsCsv,
   openSettlement,
   executeSettlement,
   cancelSettlement,
@@ -18,6 +19,37 @@ function mockFetch(status: number, body: unknown) {
   return fn;
 }
 
+/**
+ * Builds a `fetch` mock that emulates real fetch's cancellation behaviour: it
+ * captures the `AbortSignal` handed to the outgoing request and, like the real
+ * `fetch`, rejects with an `AbortError` `DOMException` when that signal aborts.
+ *
+ * `apiRequest`/`apiTextRequest` compose the caller's signal with an internal
+ * timeout controller (see `composeSignals` in `api.ts`), so the object reaching
+ * `fetch` is a *derived* signal rather than the caller's signal itself.
+ * Asserting that an abort of the caller's signal propagates to the outgoing
+ * request is the meaningful, implementation-agnostic way to verify signal
+ * forwarding — exactly the regression (a request no longer aborting on
+ * unmount/reload) that this coverage is meant to catch.
+ */
+function mockAbortableFetch() {
+  return vi.fn().mockImplementation((_url: string, init?: RequestInit) => {
+    const signal = init?.signal;
+    return new Promise<Response>((_resolve, reject) => {
+      if (signal?.aborted) {
+        reject(new DOMException("The operation was aborted.", "AbortError"));
+        return;
+      }
+      signal?.addEventListener(
+        "abort",
+        () =>
+          reject(new DOMException("The operation was aborted.", "AbortError")),
+        { once: true },
+      );
+    });
+  });
+}
+
 function settlement(status = "pending") {
   return {
     id: 1,
@@ -101,8 +133,12 @@ describe("settlementsApi", () => {
       vi.stubGlobal("fetch", fn);
 
       const { exportSettlementsCsv } = await import("./settlementsApi");
-      const result = await exportSettlementsCsv({ anchor: "b", page: 1, pageSize: 50 });
-      
+      const result = await exportSettlementsCsv({
+        anchor: "b",
+        page: 1,
+        pageSize: 50,
+      });
+
       expect(result).toBe("id,anchor\n1,a");
       const url = fn.mock.calls[0][0] as string;
       expect(url).toContain("anchor=b");
@@ -112,6 +148,68 @@ describe("settlementsApi", () => {
     });
   });
 
+  describe("abort signal forwarding", () => {
+    it("fetchSettlements forwards the abort signal to the outgoing fetch call", async () => {
+      const fn = mockAbortableFetch();
+      vi.stubGlobal("fetch", fn);
+      const controller = new AbortController();
+
+      const promise = fetchSettlements({
+        anchor: "a",
+        signal: controller.signal,
+      });
+
+      // The request reached `fetch` with an AbortSignal attached.
+      expect(fn).toHaveBeenCalledTimes(1);
+      expect(fn.mock.calls[0][0]).toContain("anchor=a");
+      const fetchSignal = fn.mock.calls[0][1].signal as AbortSignal;
+      expect(fetchSignal).toBeInstanceOf(AbortSignal);
+      expect(fetchSignal.aborted).toBe(false);
+
+      // Aborting the caller's signal propagates to the outgoing request and
+      // cancels it with an AbortError.
+      controller.abort();
+      expect(fetchSignal.aborted).toBe(true);
+      await expect(promise).rejects.toMatchObject({ name: "AbortError" });
+    });
+
+    it("fetchSettlement forwards the abort signal to the outgoing fetch call", async () => {
+      const fn = mockAbortableFetch();
+      vi.stubGlobal("fetch", fn);
+      const controller = new AbortController();
+
+      const promise = fetchSettlement(1, controller.signal);
+
+      expect(fn).toHaveBeenCalledTimes(1);
+      expect(fn.mock.calls[0][0]).toContain("/api/v1/settlements/1");
+      const fetchSignal = fn.mock.calls[0][1].signal as AbortSignal;
+      expect(fetchSignal).toBeInstanceOf(AbortSignal);
+      expect(fetchSignal.aborted).toBe(false);
+
+      controller.abort();
+      expect(fetchSignal.aborted).toBe(true);
+      await expect(promise).rejects.toMatchObject({ name: "AbortError" });
+    });
+
+    it("exportSettlementsCsv forwards the abort signal to the outgoing fetch call", async () => {
+      const fn = mockAbortableFetch();
+      vi.stubGlobal("fetch", fn);
+      const controller = new AbortController();
+
+      const promise = exportSettlementsCsv({ signal: controller.signal });
+
+      expect(fn).toHaveBeenCalledTimes(1);
+      expect(fn.mock.calls[0][0]).toContain("format=csv");
+      const fetchSignal = fn.mock.calls[0][1].signal as AbortSignal;
+      expect(fetchSignal).toBeInstanceOf(AbortSignal);
+      expect(fetchSignal.aborted).toBe(false);
+
+      controller.abort();
+      expect(fetchSignal.aborted).toBe(true);
+      await expect(promise).rejects.toMatchObject({ name: "AbortError" });
+    });
+  });
+
   it("fetches a single settlement by id", async () => {
     const fn = mockFetch(200, settlement());
     vi.stubGlobal("fetch", fn);
@@ -124,7 +222,9 @@ describe("settlementsApi", () => {
   it("surfaces a not-found error for an unknown settlement id", async () => {
     vi.stubGlobal(
       "fetch",
-      mockFetch(404, { error: { code: "NOT_FOUND", message: "no settlement" } }),
+      mockFetch(404, {
+        error: { code: "NOT_FOUND", message: "no settlement" },
+      }),
     );
 
     await expect(fetchSettlement(999)).rejects.toBeInstanceOf(ApiRequestError);