diff --git a/app/api/research/albums/[id]/measurements/route.ts b/app/api/research/albums/[id]/measurements/route.ts
new file mode 100644
index 000000000..a9dd39c8c
--- /dev/null
+++ b/app/api/research/albums/[id]/measurements/route.ts
@@ -0,0 +1,27 @@
+import { NextRequest, NextResponse } from "next/server";
+import { getCorsHeaders } from "@/lib/networking/getCorsHeaders";
+import { getAlbumMeasurementsHandler } from "@/lib/research/measurements/getAlbumMeasurementsHandler";
+
+export const maxDuration = 60;
+
+/**
+ * OPTIONS /api/research/albums/{id}/measurements — CORS preflight.
+ *
+ * @returns CORS-enabled 200 response
+ */
+export async function OPTIONS() {
+  return new NextResponse(null, { status: 200, headers: getCorsHeaders() });
+}
+
+/**
+ * GET /api/research/albums/{id}/measurements — latest measured count per track.
+ *
+ * @param request - The incoming HTTP request.
+ * @param options - Route options containing params.
+ * @param options.params - Route params containing the album id.
+ * @returns JSON album measurements or error
+ */
+export async function GET(request: NextRequest, options: { params: Promise<{ id: string }> }) {
+  const { id } = await options.params;
+  return getAlbumMeasurementsHandler(request, id);
+}
diff --git a/app/api/research/tracks/[id]/measurements/route.ts b/app/api/research/tracks/[id]/measurements/route.ts
new file mode 100644
index 000000000..ed3598014
--- /dev/null
+++ b/app/api/research/tracks/[id]/measurements/route.ts
@@ -0,0 +1,28 @@
+import { NextRequest, NextResponse } from "next/server";
+import { getCorsHeaders } from "@/lib/networking/getCorsHeaders";
+import { getTrackMeasurementsHandler } from "@/lib/research/measurements/getTrackMeasurementsHandler";
+
+export const maxDuration = 60;
+
+/**
+ * OPTIONS /api/research/tracks/{id}/measurements — CORS preflight.
+ *
+ * @returns CORS-enabled 200 response
+ */
+export async function OPTIONS() {
+  return new NextResponse(null, { status: 200, headers: getCorsHeaders() });
+}
+
+/**
+ * GET /api/research/tracks/{id}/measurements — a track's measured series, or a
+ * derived `aggregate=run_rate` projection.
+ *
+ * @param request - The incoming HTTP request.
+ * @param options - Route options containing params.
+ * @param options.params - Route params containing the track id.
+ * @returns JSON measurements or error
+ */
+export async function GET(request: NextRequest, options: { params: Promise<{ id: string }> }) {
+  const { id } = await options.params;
+  return getTrackMeasurementsHandler(request, id);
+}
diff --git a/lib/research/measurements/__tests__/getAlbumMeasurements.test.ts b/lib/research/measurements/__tests__/getAlbumMeasurements.test.ts
new file mode 100644
index 000000000..0cad8cef8
--- /dev/null
+++ b/lib/research/measurements/__tests__/getAlbumMeasurements.test.ts
@@ -0,0 +1,56 @@
+import { describe, it, expect, vi, beforeEach } from "vitest";
+import { getAlbumMeasurements } from "../getAlbumMeasurements";
+import { getAlbumPlaycounts } from "@/lib/research/playcounts/getAlbumPlaycounts";
+
+vi.mock("@/lib/research/playcounts/getAlbumPlaycounts", () => ({ getAlbumPlaycounts: vi.fn() }));
+
+describe("getAlbumMeasurements", () => {
+  beforeEach(() => vi.clearAllMocks());
+
+  it("remaps the album playcounts read into the measurements shape", async () => {
+    vi.mocked(getAlbumPlaycounts).mockResolvedValue({
+      data: {
+        status: "success",
+        album: { spotify_album_id: "AL1" },
+        playcounts: [
+          {
+            isrc: "I1",
+            spotify_track_id: "T1",
+            name: "Song",
+            platform_displayed_play_count: 500,
+            captured_at: "2026-06-12T00:00:00+00:00",
+            data_source: "apify_spotify_playcount",
+          },
+        ],
+      },
+    });
+
+    const r = await getAlbumMeasurements({ accountId: "acc_1", spotifyAlbumId: "AL1" });
+
+    expect(getAlbumPlaycounts).toHaveBeenCalledWith({ accountId: "acc_1", spotifyAlbumId: "AL1" });
+    expect(r).toEqual({
+      data: {
+        status: "success",
+        id: "AL1",
+        platform: "spotify",
+        metric: "platform_displayed_play_count",
+        measurements: [
+          {
+            isrc: "I1",
+            spotify_track_id: "T1",
+            name: "Song",
+            value: 500,
+            captured_at: "2026-06-12T00:00:00+00:00",
+            data_source: "apify_spotify_playcount",
+          },
+        ],
+      },
+    });
+  });
+
+  it("propagates a 404 from the underlying read", async () => {
+    vi.mocked(getAlbumPlaycounts).mockResolvedValue({ error: "No snapshot", status: 404 });
+    const r = await getAlbumMeasurements({ accountId: "acc_1", spotifyAlbumId: "AL1" });
+    expect(r).toEqual({ error: "No snapshot", status: 404 });
+  });
+});
diff --git a/lib/research/measurements/__tests__/getAlbumMeasurementsHandler.test.ts b/lib/research/measurements/__tests__/getAlbumMeasurementsHandler.test.ts
new file mode 100644
index 000000000..dcf32e684
--- /dev/null
+++ b/lib/research/measurements/__tests__/getAlbumMeasurementsHandler.test.ts
@@ -0,0 +1,52 @@
+import { describe, it, expect, vi, beforeEach } from "vitest";
+import { NextRequest, NextResponse } from "next/server";
+import { getAlbumMeasurementsHandler } from "../getAlbumMeasurementsHandler";
+import { validateGetAlbumMeasurementsRequest } from "../validateGetAlbumMeasurementsRequest";
+import { getAlbumMeasurements } from "../getAlbumMeasurements";
+
+vi.mock("@/lib/networking/getCorsHeaders", () => ({ getCorsHeaders: vi.fn(() => ({})) }));
+vi.mock("../validateGetAlbumMeasurementsRequest", () => ({
+  validateGetAlbumMeasurementsRequest: vi.fn(),
+}));
+vi.mock("../getAlbumMeasurements", () => ({ getAlbumMeasurements: vi.fn() }));
+
+const req = () => new NextRequest("http://x/api/research/albums/AL1/measurements");
+const validated = { accountId: "acc_1", spotifyAlbumId: "AL1" } as never;
+
+describe("getAlbumMeasurementsHandler", () => {
+  beforeEach(() => vi.clearAllMocks());
+
+  it("returns the album measurements payload on success", async () => {
+    vi.mocked(validateGetAlbumMeasurementsRequest).mockResolvedValue(validated);
+    vi.mocked(getAlbumMeasurements).mockResolvedValue({
+      data: { status: "success", id: "AL1", measurements: [] },
+    });
+    const res = await getAlbumMeasurementsHandler(req(), "AL1");
+    expect(res.status).toBe(200);
+    expect(await res.json()).toMatchObject({ id: "AL1" });
+  });
+
+  it("short-circuits with the validation response", async () => {
+    vi.mocked(validateGetAlbumMeasurementsRequest).mockResolvedValue(
+      NextResponse.json({ status: "error" }, { status: 401 }) as never,
+    );
+    const res = await getAlbumMeasurementsHandler(req(), "AL1");
+    expect(res.status).toBe(401);
+    expect(getAlbumMeasurements).not.toHaveBeenCalled();
+  });
+
+  it("maps error results to error responses", async () => {
+    vi.mocked(validateGetAlbumMeasurementsRequest).mockResolvedValue(validated);
+    vi.mocked(getAlbumMeasurements).mockResolvedValue({ error: "No snapshot", status: 404 });
+    const res = await getAlbumMeasurementsHandler(req(), "AL1");
+    expect(res.status).toBe(404);
+  });
+
+  it("returns 500 on unexpected errors", async () => {
+    const consoleError = vi.spyOn(console, "error").mockImplementation(() => {});
+    vi.mocked(validateGetAlbumMeasurementsRequest).mockRejectedValue(new Error("boom"));
+    const res = await getAlbumMeasurementsHandler(req(), "AL1");
+    expect(res.status).toBe(500);
+    consoleError.mockRestore();
+  });
+});
diff --git a/lib/research/measurements/__tests__/getTrackMeasurements.test.ts b/lib/research/measurements/__tests__/getTrackMeasurements.test.ts
new file mode 100644
index 000000000..fa58a7d8c
--- /dev/null
+++ b/lib/research/measurements/__tests__/getTrackMeasurements.test.ts
@@ -0,0 +1,117 @@
+import { describe, it, expect, vi, beforeEach } from "vitest";
+import { getTrackMeasurements } from "../getTrackMeasurements";
+import { resolveTrackIsrc } from "../resolveTrackIsrc";
+import { selectSongMeasurements } from "@/lib/supabase/song_measurements/selectSongMeasurements";
+import { computePlaycountDeltas } from "@/lib/research/playcounts/computePlaycountDeltas";
+import { deductCredits } from "@/lib/research/deductCredits";
+
+vi.mock("../resolveTrackIsrc", () => ({ resolveTrackIsrc: vi.fn() }));
+vi.mock("@/lib/supabase/song_measurements/selectSongMeasurements", () => ({
+  selectSongMeasurements: vi.fn(),
+}));
+vi.mock("@/lib/research/playcounts/computePlaycountDeltas", () => ({
+  computePlaycountDeltas: vi.fn(),
+}));
+vi.mock("@/lib/research/deductCredits", () => ({ deductCredits: vi.fn() }));
+
+const base = {
+  accountId: "acc_1",
+  id: "USQY51771120",
+  platform: "spotify",
+  metric: "platform_displayed_play_count",
+  windowDays: 365,
+};
+
+// newest-first store rows for one song
+const rows = [
+  {
+    song: "I",
+    platform: "spotify",
+    metric: "m",
+    value: 300,
+    captured_at: "2026-06-12T00:00:00+00:00",
+    data_source: "apify_spotify_playcount",
+  },
+  {
+    song: "I",
+    platform: "spotify",
+    metric: "m",
+    value: 100,
+    captured_at: "2025-06-12T00:00:00+00:00",
+    data_source: "songstats",
+  },
+];
+
+describe("getTrackMeasurements", () => {
+  beforeEach(() => {
+    vi.clearAllMocks();
+    vi.mocked(resolveTrackIsrc).mockResolvedValue("I");
+    vi.mocked(selectSongMeasurements).mockResolvedValue(rows as never);
+  });
+
+  it("404s when the id resolves to no ISRC", async () => {
+    vi.mocked(resolveTrackIsrc).mockResolvedValue(null);
+    const r = await getTrackMeasurements({ ...base });
+    expect(r).toEqual({ error: "Unknown track id", status: 404 });
+    expect(deductCredits).not.toHaveBeenCalled();
+  });
+
+  it("404s when the track has no measurements yet", async () => {
+    vi.mocked(selectSongMeasurements).mockResolvedValue([] as never);
+    const r = await getTrackMeasurements({ ...base });
+    expect((r as { status: number }).status).toBe(404);
+    expect(deductCredits).not.toHaveBeenCalled();
+  });
+
+  it("returns the ascending daily series by default and charges one credit", async () => {
+    const r = await getTrackMeasurements({ ...base });
+    expect(computePlaycountDeltas).not.toHaveBeenCalled();
+    expect(deductCredits).toHaveBeenCalledWith("acc_1");
+    expect(r).toEqual({
+      data: {
+        status: "success",
+        id: "USQY51771120",
+        platform: "spotify",
+        metric: "platform_displayed_play_count",
+        series: [
+          { date: "2025-06-12", value: 100, data_source: "songstats" },
+          { date: "2026-06-12", value: 300, data_source: "apify_spotify_playcount" },
+        ],
+      },
+    });
+  });
+
+  it("returns a run_rate aggregate over the trailing window when aggregate=run_rate", async () => {
+    vi.mocked(computePlaycountDeltas).mockReturnValue([
+      {
+        platform: "spotify",
+        metric: "platform_displayed_play_count",
+        since: { captured_at: "2025-06-12T00:00:00+00:00", value: 100 },
+        until: { captured_at: "2026-06-12T00:00:00+00:00", value: 300 },
+        delta: 200,
+        days: 365,
+        run_rate_annualized: 200,
+      },
+    ]);
+
+    const r = await getTrackMeasurements({ ...base, aggregate: "run_rate" });
+
+    // window start = latest date (2026-06-12) minus 365d
+    expect(computePlaycountDeltas).toHaveBeenCalledWith(rows, { since: "2025-06-12" });
+    expect(r).toEqual({
+      data: {
+        status: "success",
+        id: "USQY51771120",
+        platform: "spotify",
+        metric: "platform_displayed_play_count",
+        aggregate: { kind: "run_rate", window_days: 365, delta: 200, run_rate_annualized: 200 },
+      },
+    });
+  });
+
+  it("returns a null aggregate when history is insufficient for a run-rate", async () => {
+    vi.mocked(computePlaycountDeltas).mockReturnValue([]);
+    const r = await getTrackMeasurements({ ...base, aggregate: "run_rate" });
+    expect((r as { data: { aggregate: unknown } }).data.aggregate).toBeNull();
+  });
+});
diff --git a/lib/research/measurements/__tests__/getTrackMeasurementsHandler.test.ts b/lib/research/measurements/__tests__/getTrackMeasurementsHandler.test.ts
new file mode 100644
index 000000000..22c9776c2
--- /dev/null
+++ b/lib/research/measurements/__tests__/getTrackMeasurementsHandler.test.ts
@@ -0,0 +1,58 @@
+import { describe, it, expect, vi, beforeEach } from "vitest";
+import { NextRequest, NextResponse } from "next/server";
+import { getTrackMeasurementsHandler } from "../getTrackMeasurementsHandler";
+import { validateGetTrackMeasurementsRequest } from "../validateGetTrackMeasurementsRequest";
+import { getTrackMeasurements } from "../getTrackMeasurements";
+
+vi.mock("@/lib/networking/getCorsHeaders", () => ({ getCorsHeaders: vi.fn(() => ({})) }));
+vi.mock("../validateGetTrackMeasurementsRequest", () => ({
+  validateGetTrackMeasurementsRequest: vi.fn(),
+}));
+vi.mock("../getTrackMeasurements", () => ({ getTrackMeasurements: vi.fn() }));
+
+const req = () => new NextRequest("http://x/api/research/tracks/I/measurements");
+const validated = {
+  accountId: "acc_1",
+  id: "I",
+  platform: "spotify",
+  metric: "platform_displayed_play_count",
+  windowDays: 365,
+} as never;
+
+describe("getTrackMeasurementsHandler", () => {
+  beforeEach(() => vi.clearAllMocks());
+
+  it("returns the measurements payload on success", async () => {
+    vi.mocked(validateGetTrackMeasurementsRequest).mockResolvedValue(validated);
+    vi.mocked(getTrackMeasurements).mockResolvedValue({
+      data: { status: "success", id: "I", series: [] },
+    });
+    const res = await getTrackMeasurementsHandler(req(), "I");
+    expect(res.status).toBe(200);
+    expect(await res.json()).toMatchObject({ status: "success", id: "I" });
+  });
+
+  it("short-circuits with the validation response", async () => {
+    vi.mocked(validateGetTrackMeasurementsRequest).mockResolvedValue(
+      NextResponse.json({ status: "error" }, { status: 401 }) as never,
+    );
+    const res = await getTrackMeasurementsHandler(req(), "I");
+    expect(res.status).toBe(401);
+    expect(getTrackMeasurements).not.toHaveBeenCalled();
+  });
+
+  it("maps error results to error responses", async () => {
+    vi.mocked(validateGetTrackMeasurementsRequest).mockResolvedValue(validated);
+    vi.mocked(getTrackMeasurements).mockResolvedValue({ error: "Unknown track id", status: 404 });
+    const res = await getTrackMeasurementsHandler(req(), "I");
+    expect(res.status).toBe(404);
+  });
+
+  it("returns 500 on unexpected errors", async () => {
+    const consoleError = vi.spyOn(console, "error").mockImplementation(() => {});
+    vi.mocked(validateGetTrackMeasurementsRequest).mockRejectedValue(new Error("boom"));
+    const res = await getTrackMeasurementsHandler(req(), "I");
+    expect(res.status).toBe(500);
+    consoleError.mockRestore();
+  });
+});
diff --git a/lib/research/measurements/__tests__/resolveTrackIsrc.test.ts b/lib/research/measurements/__tests__/resolveTrackIsrc.test.ts
new file mode 100644
index 000000000..6b8dbc477
--- /dev/null
+++ b/lib/research/measurements/__tests__/resolveTrackIsrc.test.ts
@@ -0,0 +1,36 @@
+import { describe, it, expect, vi, beforeEach } from "vitest";
+import { resolveTrackIsrc } from "../resolveTrackIsrc";
+import { selectSongIdentifiers } from "@/lib/supabase/song_identifiers/selectSongIdentifiers";
+
+vi.mock("@/lib/supabase/song_identifiers/selectSongIdentifiers", () => ({
+  selectSongIdentifiers: vi.fn(),
+}));
+
+describe("resolveTrackIsrc", () => {
+  beforeEach(() => vi.clearAllMocks());
+
+  it("returns an ISRC-shaped id unchanged without a lookup", async () => {
+    const out = await resolveTrackIsrc("USQY51771120");
+    expect(out).toBe("USQY51771120");
+    expect(selectSongIdentifiers).not.toHaveBeenCalled();
+  });
+
+  it("resolves a Spotify track id to its ISRC via the identifier mappings", async () => {
+    vi.mocked(selectSongIdentifiers).mockResolvedValue([
+      { song: "USQY51771120", platform: "spotify", identifier_type: "track_id", value: "6Rmabc" },
+    ]);
+    const out = await resolveTrackIsrc("6Rmabc");
+    expect(selectSongIdentifiers).toHaveBeenCalledWith({
+      platform: "spotify",
+      identifierType: "track_id",
+      values: ["6Rmabc"],
+    });
+    expect(out).toBe("USQY51771120");
+  });
+
+  it("returns null when a non-ISRC id maps to nothing", async () => {
+    vi.mocked(selectSongIdentifiers).mockResolvedValue([]);
+    // a 22-char Spotify-style id (not ISRC-shaped) that has no mapping
+    expect(await resolveTrackIsrc("6rqhFgbbKwnb9MLmUQDhG6")).toBeNull();
+  });
+});
diff --git a/lib/research/measurements/__tests__/validateGetAlbumMeasurementsRequest.test.ts b/lib/research/measurements/__tests__/validateGetAlbumMeasurementsRequest.test.ts
new file mode 100644
index 000000000..092a6c8f1
--- /dev/null
+++ b/lib/research/measurements/__tests__/validateGetAlbumMeasurementsRequest.test.ts
@@ -0,0 +1,31 @@
+import { describe, it, expect, vi, beforeEach } from "vitest";
+import { NextRequest, NextResponse } from "next/server";
+import { validateGetAlbumMeasurementsRequest } from "../validateGetAlbumMeasurementsRequest";
+import { validateAuthContext } from "@/lib/auth/validateAuthContext";
+
+vi.mock("@/lib/credits/ensureCreditsOrShortCircuit", () => ({
+  ensureCreditsOrShortCircuit: vi.fn().mockResolvedValue(null),
+}));
+vi.mock("@/lib/auth/validateAuthContext", () => ({ validateAuthContext: vi.fn() }));
+
+const req = () => new NextRequest("http://x/api/research/albums/AL1/measurements");
+
+describe("validateGetAlbumMeasurementsRequest", () => {
+  beforeEach(() => {
+    vi.clearAllMocks();
+    vi.mocked(validateAuthContext).mockResolvedValue({ accountId: "acc_1" } as never);
+  });
+
+  it("returns the auth response (401) when auth fails", async () => {
+    vi.mocked(validateAuthContext).mockResolvedValue(
+      NextResponse.json({ status: "error" }, { status: 401 }) as never,
+    );
+    const r = await validateGetAlbumMeasurementsRequest(req(), "AL1");
+    expect((r as NextResponse).status).toBe(401);
+  });
+
+  it("returns account + album id on success", async () => {
+    const r = await validateGetAlbumMeasurementsRequest(req(), "AL1");
+    expect(r).toEqual({ accountId: "acc_1", spotifyAlbumId: "AL1" });
+  });
+});
diff --git a/lib/research/measurements/__tests__/validateGetTrackMeasurementsRequest.test.ts b/lib/research/measurements/__tests__/validateGetTrackMeasurementsRequest.test.ts
new file mode 100644
index 000000000..b4159bbd6
--- /dev/null
+++ b/lib/research/measurements/__tests__/validateGetTrackMeasurementsRequest.test.ts
@@ -0,0 +1,52 @@
+import { describe, it, expect, vi, beforeEach } from "vitest";
+import { NextRequest, NextResponse } from "next/server";
+import { validateGetTrackMeasurementsRequest } from "../validateGetTrackMeasurementsRequest";
+import { validateAuthContext } from "@/lib/auth/validateAuthContext";
+
+vi.mock("@/lib/credits/ensureCreditsOrShortCircuit", () => ({
+  ensureCreditsOrShortCircuit: vi.fn().mockResolvedValue(null),
+}));
+vi.mock("@/lib/auth/validateAuthContext", () => ({ validateAuthContext: vi.fn() }));
+
+const req = (qs = "") =>
+  new NextRequest(`http://x/api/research/tracks/USQY51771120/measurements${qs}`);
+
+describe("validateGetTrackMeasurementsRequest", () => {
+  beforeEach(() => {
+    vi.clearAllMocks();
+    vi.mocked(validateAuthContext).mockResolvedValue({ accountId: "acc_1" } as never);
+  });
+
+  it("returns the auth response (401) when auth fails", async () => {
+    vi.mocked(validateAuthContext).mockResolvedValue(
+      NextResponse.json({ status: "error" }, { status: 401 }) as never,
+    );
+    const r = await validateGetTrackMeasurementsRequest(req(), "USQY51771120");
+    expect((r as NextResponse).status).toBe(401);
+  });
+
+  it("400s when aggregate is not run_rate", async () => {
+    const r = await validateGetTrackMeasurementsRequest(req("?aggregate=avg"), "USQY51771120");
+    expect((r as NextResponse).status).toBe(400);
+  });
+
+  it("defaults platform, metric, window; no aggregate", async () => {
+    const r = await validateGetTrackMeasurementsRequest(req(), "USQY51771120");
+    expect(r).toEqual({
+      accountId: "acc_1",
+      id: "USQY51771120",
+      platform: "spotify",
+      metric: "platform_displayed_play_count",
+      aggregate: undefined,
+      windowDays: 365,
+    });
+  });
+
+  it("parses aggregate=run_rate and window=90d", async () => {
+    const r = await validateGetTrackMeasurementsRequest(
+      req("?aggregate=run_rate&window=90d"),
+      "USQY51771120",
+    );
+    expect(r).toMatchObject({ aggregate: "run_rate", windowDays: 90 });
+  });
+});
diff --git a/lib/research/measurements/getAlbumMeasurements.ts b/lib/research/measurements/getAlbumMeasurements.ts
new file mode 100644
index 000000000..3ffc7c24f
--- /dev/null
+++ b/lib/research/measurements/getAlbumMeasurements.ts
@@ -0,0 +1,50 @@
+import { getAlbumPlaycounts } from "@/lib/research/playcounts/getAlbumPlaycounts";
+
+const METRIC = "platform_displayed_play_count";
+
+export type GetAlbumMeasurementsResult = { data: unknown } | { error: string; status: number };
+
+type PlaycountRow = {
+  isrc: string;
+  spotify_track_id: string | null;
+  name: string | null;
+  platform_displayed_play_count: number;
+  captured_at: string;
+  data_source: string;
+};
+
+/**
+ * Latest measured count per track on an album, in the `measurements` shape —
+ * a thin remap over {@link getAlbumPlaycounts} (which serves the store and
+ * deducts credits). Consolidates `GET /api/research/playcounts`.
+ *
+ * @param params.accountId - The authenticated account
+ * @param params.spotifyAlbumId - The Spotify album id
+ */
+export async function getAlbumMeasurements(params: {
+  accountId: string;
+  spotifyAlbumId: string;
+}): Promise<GetAlbumMeasurementsResult> {
+  const result = await getAlbumPlaycounts(params);
+  if ("error" in result) return result;
+
+  const { playcounts } = result.data as { playcounts: PlaycountRow[] };
+  const measurements = playcounts.map(p => ({
+    isrc: p.isrc,
+    spotify_track_id: p.spotify_track_id,
+    name: p.name,
+    value: p.platform_displayed_play_count,
+    captured_at: p.captured_at,
+    data_source: p.data_source,
+  }));
+
+  return {
+    data: {
+      status: "success",
+      id: params.spotifyAlbumId,
+      platform: "spotify",
+      metric: METRIC,
+      measurements,
+    },
+  };
+}
diff --git a/lib/research/measurements/getAlbumMeasurementsHandler.ts b/lib/research/measurements/getAlbumMeasurementsHandler.ts
new file mode 100644
index 000000000..903739e18
--- /dev/null
+++ b/lib/research/measurements/getAlbumMeasurementsHandler.ts
@@ -0,0 +1,33 @@
+import { type NextRequest, NextResponse } from "next/server";
+import { errorResponse } from "@/lib/networking/errorResponse";
+import { successResponse } from "@/lib/networking/successResponse";
+import { getAlbumMeasurements } from "@/lib/research/measurements/getAlbumMeasurements";
+import { validateGetAlbumMeasurementsRequest } from "@/lib/research/measurements/validateGetAlbumMeasurementsRequest";
+
+/**
+ * GET /api/research/albums/{id}/measurements
+ *
+ * Latest measured count per track on an album, from the store. Consolidates
+ * `GET /api/research/playcounts`.
+ *
+ * @param request - The incoming HTTP request.
+ * @param id - The Spotify album id from the path.
+ * @returns The JSON response.
+ */
+export async function getAlbumMeasurementsHandler(
+  request: NextRequest,
+  id: string,
+): Promise<NextResponse> {
+  try {
+    const validated = await validateGetAlbumMeasurementsRequest(request, id);
+    if (validated instanceof NextResponse) return validated;
+
+    const result = await getAlbumMeasurements(validated);
+    if ("error" in result) return errorResponse(result.error, result.status);
+
+    return successResponse(result.data as Record<string, unknown>);
+  } catch (error) {
+    console.error("[ERROR] getAlbumMeasurementsHandler:", error);
+    return errorResponse("Internal error", 500);
+  }
+}
diff --git a/lib/research/measurements/getTrackMeasurements.ts b/lib/research/measurements/getTrackMeasurements.ts
new file mode 100644
index 000000000..e36aa400d
--- /dev/null
+++ b/lib/research/measurements/getTrackMeasurements.ts
@@ -0,0 +1,84 @@
+import { resolveTrackIsrc } from "@/lib/research/measurements/resolveTrackIsrc";
+import { selectSongMeasurements } from "@/lib/supabase/song_measurements/selectSongMeasurements";
+import { computePlaycountDeltas } from "@/lib/research/playcounts/computePlaycountDeltas";
+import { deductCredits } from "@/lib/research/deductCredits";
+
+const DAY_MS = 24 * 60 * 60 * 1000;
+
+export type GetTrackMeasurementsParams = {
+  accountId: string;
+  id: string;
+  platform: string;
+  metric: string;
+  windowDays: number;
+  aggregate?: "run_rate";
+};
+
+export type GetTrackMeasurementsResult = { data: unknown } | { error: string; status: number };
+
+const NO_DATA_ERROR =
+  "No measurements for this track yet — create a historical measurement-job to backfill it";
+
+/**
+ * A track's measured series from the store, or — when `aggregate=run_rate` —
+ * the trailing-window annualized run-rate (a projection of the same series via
+ * {@link computePlaycountDeltas}). Consolidates `track/historic-stats` and
+ * `track/playcount-deltas`. 404 when the id resolves to no ISRC or no
+ * measurements exist. Deducts research credits only on a successful read.
+ *
+ * @param params - account, provider-neutral track id, platform/metric, window
+ */
+export async function getTrackMeasurements(
+  params: GetTrackMeasurementsParams,
+): Promise<GetTrackMeasurementsResult> {
+  const isrc = await resolveTrackIsrc(params.id);
+  if (!isrc) return { error: "Unknown track id", status: 404 };
+
+  const rows = await selectSongMeasurements({
+    song: isrc,
+    platform: params.platform,
+    metric: params.metric,
+  });
+  if (rows.length === 0) return { error: NO_DATA_ERROR, status: 404 };
+
+  await deductCredits(params.accountId);
+
+  const head = {
+    status: "success",
+    id: params.id,
+    platform: params.platform,
+    metric: params.metric,
+  };
+
+  if (params.aggregate === "run_rate") {
+    // window start = latest capture date minus the window
+    const latestDate = rows[0].captured_at.slice(0, 10);
+    const since = new Date(
+      new Date(`${latestDate}T00:00:00Z`).getTime() - params.windowDays * DAY_MS,
+    )
+      .toISOString()
+      .slice(0, 10);
+    const deltas = computePlaycountDeltas(rows, { since });
+    const match =
+      deltas.find(d => d.platform === params.platform && d.metric === params.metric) ?? deltas[0];
+    const aggregate = match
+      ? {
+          kind: "run_rate" as const,
+          window_days: params.windowDays,
+          delta: match.delta,
+          run_rate_annualized: match.run_rate_annualized,
+        }
+      : null;
+    return { data: { ...head, aggregate } };
+  }
+
+  const series = [...rows]
+    .sort((a, b) => (a.captured_at < b.captured_at ? -1 : 1))
+    .map(row => ({
+      date: row.captured_at.slice(0, 10),
+      value: row.value,
+      data_source: row.data_source,
+    }));
+
+  return { data: { ...head, series } };
+}
diff --git a/lib/research/measurements/getTrackMeasurementsHandler.ts b/lib/research/measurements/getTrackMeasurementsHandler.ts
new file mode 100644
index 000000000..128c88995
--- /dev/null
+++ b/lib/research/measurements/getTrackMeasurementsHandler.ts
@@ -0,0 +1,34 @@
+import { type NextRequest, NextResponse } from "next/server";
+import { errorResponse } from "@/lib/networking/errorResponse";
+import { successResponse } from "@/lib/networking/successResponse";
+import { getTrackMeasurements } from "@/lib/research/measurements/getTrackMeasurements";
+import { validateGetTrackMeasurementsRequest } from "@/lib/research/measurements/validateGetTrackMeasurementsRequest";
+
+/**
+ * GET /api/research/tracks/{id}/measurements
+ *
+ * A track's measured series from the store, or — with `aggregate=run_rate` —
+ * the trailing-window annualized run-rate. Consolidates `track/historic-stats`
+ * and `track/playcount-deltas`.
+ *
+ * @param request - The incoming HTTP request.
+ * @param id - The provider-neutral track id from the path.
+ * @returns The JSON response.
+ */
+export async function getTrackMeasurementsHandler(
+  request: NextRequest,
+  id: string,
+): Promise<NextResponse> {
+  try {
+    const validated = await validateGetTrackMeasurementsRequest(request, id);
+    if (validated instanceof NextResponse) return validated;
+
+    const result = await getTrackMeasurements(validated);
+    if ("error" in result) return errorResponse(result.error, result.status);
+
+    return successResponse(result.data as Record<string, unknown>);
+  } catch (error) {
+    console.error("[ERROR] getTrackMeasurementsHandler:", error);
+    return errorResponse("Internal error", 500);
+  }
+}
diff --git a/lib/research/measurements/resolveTrackIsrc.ts b/lib/research/measurements/resolveTrackIsrc.ts
new file mode 100644
index 000000000..bc085561d
--- /dev/null
+++ b/lib/research/measurements/resolveTrackIsrc.ts
@@ -0,0 +1,23 @@
+import { selectSongIdentifiers } from "@/lib/supabase/song_identifiers/selectSongIdentifiers";
+
+/** ISRC shape: 2 letters (country) + 10 alphanumerics. */
+const ISRC_PATTERN = /^[A-Za-z]{2}[A-Za-z0-9]{10}$/;
+
+/**
+ * Resolve a provider-neutral track id (ISRC or Spotify track id) to its ISRC —
+ * the key the measurement store is indexed by. ISRC-shaped ids pass through;
+ * anything else is treated as a Spotify track id and reverse-looked-up.
+ *
+ * @param id - ISRC or Spotify track id
+ * @returns The ISRC, or null when a non-ISRC id maps to nothing
+ */
+export async function resolveTrackIsrc(id: string): Promise<string | null> {
+  if (ISRC_PATTERN.test(id)) return id;
+
+  const rows = await selectSongIdentifiers({
+    platform: "spotify",
+    identifierType: "track_id",
+    values: [id],
+  });
+  return rows[0]?.song ?? null;
+}
diff --git a/lib/research/measurements/validateGetAlbumMeasurementsRequest.ts b/lib/research/measurements/validateGetAlbumMeasurementsRequest.ts
new file mode 100644
index 000000000..5195f7455
--- /dev/null
+++ b/lib/research/measurements/validateGetAlbumMeasurementsRequest.ts
@@ -0,0 +1,28 @@
+import { type NextRequest, NextResponse } from "next/server";
+import { validateAuthContext } from "@/lib/auth/validateAuthContext";
+import { ensureResearchCredits } from "@/lib/research/ensureResearchCredits";
+
+export type ValidatedGetAlbumMeasurementsRequest = {
+  accountId: string;
+  spotifyAlbumId: string;
+};
+
+/**
+ * Validates `GET /api/research/albums/{id}/measurements` — auth + research
+ * credits. The album id comes from the path.
+ *
+ * @param request - The incoming HTTP request.
+ * @param id - The Spotify album id from the path.
+ */
+export async function validateGetAlbumMeasurementsRequest(
+  request: NextRequest,
+  id: string,
+): Promise<NextResponse | ValidatedGetAlbumMeasurementsRequest> {
+  const authResult = await validateAuthContext(request);
+  if (authResult instanceof NextResponse) return authResult;
+
+  const short = await ensureResearchCredits(authResult.accountId);
+  if (short) return short;
+
+  return { accountId: authResult.accountId, spotifyAlbumId: id };
+}
diff --git a/lib/research/measurements/validateGetTrackMeasurementsRequest.ts b/lib/research/measurements/validateGetTrackMeasurementsRequest.ts
new file mode 100644
index 000000000..8bdfbc681
--- /dev/null
+++ b/lib/research/measurements/validateGetTrackMeasurementsRequest.ts
@@ -0,0 +1,55 @@
+import { type NextRequest, NextResponse } from "next/server";
+import { validateAuthContext } from "@/lib/auth/validateAuthContext";
+import { ensureResearchCredits } from "@/lib/research/ensureResearchCredits";
+import { errorResponse } from "@/lib/networking/errorResponse";
+
+const DEFAULT_PLATFORM = "spotify";
+const DEFAULT_METRIC = "platform_displayed_play_count";
+const DEFAULT_WINDOW_DAYS = 365;
+
+export type ValidatedGetTrackMeasurementsRequest = {
+  accountId: string;
+  id: string;
+  platform: string;
+  metric: string;
+  aggregate?: "run_rate";
+  windowDays: number;
+};
+
+/**
+ * Validates `GET /api/research/tracks/{id}/measurements` — auth, research
+ * credits, and the projection query params (`platform`, `metric`, `aggregate`,
+ * `window`). `aggregate` may only be `run_rate`; `window` like `365d` → days.
+ *
+ * @param request - The incoming HTTP request.
+ * @param id - The provider-neutral track id from the path.
+ */
+export async function validateGetTrackMeasurementsRequest(
+  request: NextRequest,
+  id: string,
+): Promise<NextResponse | ValidatedGetTrackMeasurementsRequest> {
+  const authResult = await validateAuthContext(request);
+  if (authResult instanceof NextResponse) return authResult;
+
+  const { searchParams } = new URL(request.url);
+
+  const aggregateParam = searchParams.get("aggregate");
+  if (aggregateParam !== null && aggregateParam !== "run_rate") {
+    return errorResponse("aggregate must be run_rate", 400);
+  }
+
+  const short = await ensureResearchCredits(authResult.accountId);
+  if (short) return short;
+
+  const windowMatch = (searchParams.get("window") ?? "").match(/^(\d+)d?$/);
+  const windowDays = windowMatch ? Number(windowMatch[1]) : DEFAULT_WINDOW_DAYS;
+
+  return {
+    accountId: authResult.accountId,
+    id,
+    platform: searchParams.get("platform") ?? DEFAULT_PLATFORM,
+    metric: searchParams.get("metric") ?? DEFAULT_METRIC,
+    aggregate: aggregateParam === "run_rate" ? "run_rate" : undefined,
+    windowDays,
+  };
+}