diff --git a/src/harness/run.test.ts b/src/harness/run.test.ts
index 422a4aa6..e0a520f1 100644
--- a/src/harness/run.test.ts
+++ b/src/harness/run.test.ts
@@ -172,6 +172,19 @@ describe("runBenchmark", () => {
     expect(result.usage.generationTimeMs).toBe(600);
     expect(result.sampleScores[0]?.generationIds).toEqual(["fake-Q1 target B"]);
   });
+  it("runs only the requested epoch", async () => {
+    const model = fakeModel(() => "Answer: B");
+    const solver = generate(model.service, {
+      temperature: 0.5,
+      reasoningEffort: "high",
+    });
+    const result = await runPromise(
+      runBenchmark({ epochs: 3, epoch: 2, maxConcurrency: 4 }).pipe(
+        provide(makeLayers(model, solver))
+      )
+    );
+    expect(result.sampleScores.map((score) => score.epoch)).toEqual([2, 2]);
+  });
   it("captures per-sample message trajectories", async () => {
     const model = fakeModel(() => "Answer: B");
     const solver = chain(
diff --git a/src/harness/run.ts b/src/harness/run.ts
index 7f004f5f..fc6e6833 100644
--- a/src/harness/run.ts
+++ b/src/harness/run.ts
@@ -49,6 +49,7 @@ import { Solver } from "./solver";
 
 export interface RunConfig {
   readonly epochs: number;
+  readonly epoch?: number;
   readonly maxConcurrency: number;
   readonly range?: {
     readonly start?: number;
@@ -83,7 +84,7 @@ type EvalOutcome = {
 
 function sampleEpochStream(
   dataset: DatasetService,
-  epochs: number,
+  epochs: readonly number[],
   range:
     | {
         readonly start?: number;
@@ -96,7 +97,7 @@ function sampleEpochStream(
     streamZipWithIndex,
     streamFlatMap(([sample, i]) =>
       streamFromIterable(
-        Array.from({ length: epochs }, (_, epoch) => ({
+        epochs.map((epoch) => ({
           sample,
           epoch,
           sampleIndex: baseIndex + i,
@@ -337,7 +338,9 @@ export function runBenchmark(
     effectFlatMap((dataset) => {
       const sampleEpochs = sampleEpochStream(
         dataset,
-        config.epochs,
+        config.epoch === undefined
+          ? Array.from({ length: config.epochs }, (_, epoch) => epoch)
+          : [config.epoch],
         config.range
       );
       const initialAcc: FoldAccumulator = {
diff --git a/src/runner/run-by-id.ts b/src/runner/run-by-id.ts
index e7e5c56e..aefe430d 100644
--- a/src/runner/run-by-id.ts
+++ b/src/runner/run-by-id.ts
@@ -56,6 +56,7 @@ export interface RunBenchmarkInput {
   readonly baseUrl?: string;
   readonly benchmarkConfig: BenchmarkRunConfig;
   readonly epochs: number;
+  readonly epoch?: number;
   readonly maxConcurrency: number;
   readonly range?: {
     readonly start?: number;
@@ -96,6 +97,7 @@ export function runBenchmarkById(
   const model = modelFromConfig(input.benchmarkConfig);
   const runConfig: RunConfig = definedValues({
     epochs: input.epochs,
+    epoch: input.epoch,
     maxConcurrency: input.maxConcurrency,
     range: input.range,
     degradeSolverErrors: benchmark.degradeSolverErrors,