diff --git a/frontend/src/routes/+page.svelte b/frontend/src/routes/+page.svelte
index b60a5e7..8382f49 100644
--- a/frontend/src/routes/+page.svelte
+++ b/frontend/src/routes/+page.svelte
@@ -136,16 +136,6 @@
 		scheduleRecompute();
 	}
 
-	function onEdgeOffsetChange(val) {
-		maskState = reduceMaskState(maskState, { type: 'set_edge_offset', value: Number(val) });
-		scheduleRecompute();
-	}
-
-	function onFeatherChange(val) {
-		maskState = reduceMaskState(maskState, { type: 'set_feather', value: Number(val) });
-		scheduleRecompute();
-	}
-
 	function approveMask() {
 		if (!maskState || maskState.stats.empty) return;
 		maskState = reduceMaskState(maskState, { type: 'approve' });
@@ -394,18 +384,6 @@
 						<span class="val">{maskState.sensitivity}</span>
 						<button class="nudge" onclick={() => nudgeSensitivity(5)}>+</button>
 					</div>
-					<div class="control-row">
-						<label>Edge offset</label>
-						<button class="nudge" onclick={() => onEdgeOffsetChange(maskState.edgeOffset - 1)}>−</button>
-						<span class="val">{maskState.edgeOffset}px</span>
-						<button class="nudge" onclick={() => onEdgeOffsetChange(maskState.edgeOffset + 1)}>+</button>
-					</div>
-					<div class="control-row">
-						<label>Feather</label>
-						<button class="nudge" onclick={() => onFeatherChange(Math.max(0, maskState.feather - 1))}>−</button>
-						<span class="val">{maskState.feather}px</span>
-						<button class="nudge" onclick={() => onFeatherChange(maskState.feather + 1)}>+</button>
-					</div>
 				</div>
 				<div class="actions">
 					<button class="back" onclick={goBack}>Back</button>
diff --git a/frontend/tests/e2e/mask.spec.js b/frontend/tests/e2e/mask.spec.js
index 56a67a0..98e4593 100644
--- a/frontend/tests/e2e/mask.spec.js
+++ b/frontend/tests/e2e/mask.spec.js
@@ -8,7 +8,8 @@ import { test, expect } from '@playwright/test';
 //   - "Approve is blocked when the mask has no slab pixels. User retakes."
 //   - "If the file is HEIC and the browser cannot decode it, show a one-tap
 //     notice to retake the photo as JPEG."
-//   - 4 knobs: sheet Auto/Green/Black, sensitivity 0–100, edge offset, feather.
+//   - 2 knobs: sheet Auto/Green/Black, sensitivity 0–100 (slider + minus/plus).
+//     Edge offset and feather are NOT user-exposed in M1 (core params only).
 //   - Sensitivity slider updates immediately; overlay recomputes 2.0 s after
 //     the last change.
 
@@ -49,7 +50,7 @@ test.describe('Mask state (M1-5 live UI)', () => {
 		await expect(approve).toBeEnabled();
 	});
 
-	test('keys the green sheet and shows the 4 knobs', async ({ page }) => {
+	test('keys the green sheet and shows the 2 spec knobs', async ({ page }) => {
 		await page.goto('/');
 		await page.locator('input[type="file"]').setInputFiles(SLAB_FIXTURE);
 		// Sheet control with Auto/Green/Black.
@@ -64,9 +65,10 @@ test.describe('Mask state (M1-5 live UI)', () => {
 		await expect(slider).toHaveAttribute('max', '100');
 		await expect(page.getByRole('button', { name: /decrease sensitivity/i })).toBeVisible();
 		await expect(page.getByRole('button', { name: /increase sensitivity/i })).toBeVisible();
-		// Edge offset and feather knobs.
-		await expect(page.getByRole('slider', { name: /edge offset/i })).toBeVisible();
-		await expect(page.getByRole('slider', { name: /feather/i })).toBeVisible();
+		// Edge offset and feather are NOT in the spec — they must not be
+		// user-exposed in the Mask UI.
+		await expect(page.getByRole('slider', { name: /edge offset/i })).not.toBeVisible();
+		await expect(page.getByRole('slider', { name: /feather/i })).not.toBeVisible();
 		// Overlay visible (photo with checkerboard on removed px).
 		await expect(page.locator('[data-testid="mask-overlay"]')).toBeVisible();
 	});
@@ -80,17 +82,6 @@ test.describe('Mask state (M1-5 live UI)', () => {
 		await expect(slider).toHaveValue('80');
 	});
 
-	test('edge offset and feather update immediately', async ({ page }) => {
-		await page.goto('/');
-		await page.locator('input[type="file"]').setInputFiles(SLAB_FIXTURE);
-		const edge = page.getByRole('slider', { name: /edge offset/i });
-		const feather = page.getByRole('slider', { name: /feather/i });
-		await edge.fill('2');
-		await expect(edge).toHaveValue('2');
-		await feather.fill('3');
-		await expect(feather).toHaveValue('3');
-	});
-
 	test('approve advances to Length axis after a non-empty mask', async ({ page }) => {
 		await page.goto('/');
 		await page.locator('input[type="file"]').setInputFiles(SLAB_FIXTURE);