diff --git a/packages/cli/CHANGELOG.md b/packages/cli/CHANGELOG.md
index 24cc4f5..c837cd8 100644
--- a/packages/cli/CHANGELOG.md
+++ b/packages/cli/CHANGELOG.md
@@ -3,11 +3,20 @@
 Notable changes to `@framesieve/cli`. Pre-1.0 the CLI surface may
 change between minor versions.
 
+## 0.2.1
+
+- `--mode <previous|reference>` selects the diff comparison baseline
+  (core 0.4.0's reference mode), and `--persist <ms>` sets
+  `policy.referencePersistMs`. `--sweep referencePersistMs=a:b:step`
+  calibrates the reference-mode persistence window against a recording,
+  so `fsieve replay <dir> --mode reference --sweep referencePersistMs=0:4000:1000`
+  shows the emit knee. No behavior change to existing flags.
+
 ## 0.2.0
 
 - Requires `framesieve` `^0.4.0` and `@framesieve/adapters` `^0.3.0`
-  (core adds the opt-in reference diff mode). `fsieve replay --sweep`
-  can vary `diff.mode` like any other gate option; no new CLI flags.
+  (core adds the opt-in reference diff mode). No CLI surface change in
+  this version.
 
 ## 0.1.1
 
diff --git a/packages/cli/package.json b/packages/cli/package.json
index adff617..b1231e1 100644
--- a/packages/cli/package.json
+++ b/packages/cli/package.json
@@ -1,6 +1,6 @@
 {
   "name": "@framesieve/cli",
-  "version": "0.2.0",
+  "version": "0.2.1",
   "description": "fsieve command: replay recordings and sweep gate parameters offline.",
   "license": "Apache-2.0",
   "type": "module",
diff --git a/packages/cli/src/main.ts b/packages/cli/src/main.ts
index 667bbd2..f04fc37 100644
--- a/packages/cli/src/main.ts
+++ b/packages/cli/src/main.ts
@@ -20,8 +20,10 @@ Options:
   --sweep <param=a:b:step>   replay once per value of <param>;
                              params: downsampleFactor, luminanceThreshold,
                              blockChangeRatio, minChangedBlocks, windowSize,
-                             debounceMs, minIntervalMs, maxSilenceMs
+                             debounceMs, minIntervalMs, maxSilenceMs,
+                             referencePersistMs
   --algorithm <name>         diff algorithm: downsample | pixel | edge
+  --mode <name>              diff comparison: previous | reference
   --downsample <n>           diff.downsampleFactor
   --luminance <n>            diff.luminanceThreshold
   --grid <cols>x<rows>       blocks grid, e.g. 16x9
@@ -32,6 +34,7 @@ Options:
   --debounce <ms>            policy.debounceMs
   --min-interval <ms>        policy.minIntervalMs
   --max-silence <ms>         policy.maxSilenceMs
+  --persist <ms>             policy.referencePersistMs (reference mode)
   -h, --help                 show this help
 `;
 
@@ -43,7 +46,8 @@ type SweepParam =
   | "windowSize"
   | "debounceMs"
   | "minIntervalMs"
-  | "maxSilenceMs";
+  | "maxSilenceMs"
+  | "referencePersistMs";
 
 const SWEEP_PARAMS: readonly SweepParam[] = [
   "downsampleFactor",
@@ -54,6 +58,7 @@ const SWEEP_PARAMS: readonly SweepParam[] = [
   "debounceMs",
   "minIntervalMs",
   "maxSilenceMs",
+  "referencePersistMs",
 ];
 
 class UsageError extends Error {}
@@ -86,6 +91,7 @@ function withParam(
     case "debounceMs":
     case "minIntervalMs":
     case "maxSilenceMs":
+    case "referencePersistMs":
       return { ...options, policy: { ...options.policy, [param]: value } };
   }
 }
@@ -144,6 +150,13 @@ function buildOptions(values: Record<string, unknown>): FrameGateOptions {
     }
     options = { ...options, diff: { ...options.diff, algorithm } };
   }
+  const mode = str("mode");
+  if (mode !== undefined) {
+    if (mode !== "previous" && mode !== "reference") {
+      throw new UsageError(`--mode expects previous or reference`);
+    }
+    options = { ...options, diff: { ...options.diff, mode } };
+  }
   const num = (flag: string, param: SweepParam): void => {
     const v = str(flag);
     if (v !== undefined) options = withParam(options, param, parseNumber(`--${flag}`, v));
@@ -156,6 +169,7 @@ function buildOptions(values: Record<string, unknown>): FrameGateOptions {
   num("debounce", "debounceMs");
   num("min-interval", "minIntervalMs");
   num("max-silence", "maxSilenceMs");
+  num("persist", "referencePersistMs");
 
   const grid = str("grid");
   if (grid !== undefined) {
@@ -214,6 +228,7 @@ export async function run(argv: string[]): Promise<number> {
         json: { type: "boolean" },
         sweep: { type: "string" },
         algorithm: { type: "string" },
+        mode: { type: "string" },
         downsample: { type: "string" },
         luminance: { type: "string" },
         grid: { type: "string" },
@@ -224,6 +239,7 @@ export async function run(argv: string[]): Promise<number> {
         debounce: { type: "string" },
         "min-interval": { type: "string" },
         "max-silence": { type: "string" },
+        persist: { type: "string" },
         help: { type: "boolean", short: "h" },
       },
     });
diff --git a/packages/cli/test/cli.test.ts b/packages/cli/test/cli.test.ts
index b2e03a0..d48a4c0 100644
--- a/packages/cli/test/cli.test.ts
+++ b/packages/cli/test/cli.test.ts
@@ -138,10 +138,57 @@ test("sweeping blockChangeRatio handles fractional steps without float drift", (
   assert.deepEqual(values, ["0.1", "0.15", "0.2", "0.25", "0.3", "0.35", "0.4"]);
 });
 
+test("--mode reference matches the library's reference-mode decisions", async () => {
+  const { stdout, status } = fsieve("replay", recordingDir, "--json", "--mode", "reference");
+  assert.equal(status, 0);
+  const fromCli = stdout.trim().split("\n").map(parseDecisionLine);
+  const fromLib = await replay(recordingDir, { diff: { mode: "reference" } });
+  assert.deepEqual(fromCli, canonical(fromLib.decisions));
+});
+
+test("--persist sets referencePersistMs, matching the library", async () => {
+  const { stdout, status } = fsieve(
+    "replay",
+    recordingDir,
+    "--json",
+    "--mode",
+    "reference",
+    "--persist",
+    "1000",
+  );
+  assert.equal(status, 0);
+  const fromCli = stdout.trim().split("\n").map(parseDecisionLine);
+  const fromLib = await replay(recordingDir, {
+    diff: { mode: "reference" },
+    policy: { referencePersistMs: 1000 },
+  });
+  assert.deepEqual(fromCli, canonical(fromLib.decisions));
+});
+
+test("--sweep referencePersistMs prints one row per value", () => {
+  const { stdout, status } = fsieve(
+    "replay",
+    recordingDir,
+    "--mode",
+    "reference",
+    "--sweep",
+    "referencePersistMs=0:2000:1000",
+  );
+  assert.equal(status, 0);
+  const rows = stdout
+    .trim()
+    .split("\n")
+    .filter((l) => /^ {2}\d/.test(l));
+  assert.equal(rows.length, 3); // 0, 1000, 2000
+  assert.match(rows[0]!, /^ {2}0\b/);
+  assert.match(rows[2]!, /^ {2}2000\b/);
+});
+
 test("usage errors exit nonzero", () => {
   assert.equal(fsieve().status, 1);
   assert.equal(fsieve("replay").status, 1);
   assert.equal(fsieve("replay", recordingDir, "--sweep", "bogus=1:2:1").status, 1);
+  assert.equal(fsieve("replay", recordingDir, "--mode", "sideways").status, 1);
   assert.equal(fsieve("replay", join(tmpdir(), "does-not-exist-xyz")).status, 1);
 });