diff --git a/frontend/src/__tests__/plans.test.ts b/frontend/src/__tests__/plans.test.ts
index a436840a3..e9591d981 100644
--- a/frontend/src/__tests__/plans.test.ts
+++ b/frontend/src/__tests__/plans.test.ts
@@ -3463,11 +3463,22 @@ describe('Plans Module', () => {
       expect(api.createPlannedPurchases).not.toHaveBeenCalled();
     });
 
-    test('weekly 20% plan currently prefills as immediate and previews 1 step (#1156)', async () => {
-      // Documents current behaviour of the Edit prefill, which maps weekly != 25% to `immediate`; see #1156.
-      // Invert this expectation (weekly 20% should preview 5 steps) when #1156 is fixed.
-      await openEdit(backendPlan({ type: 'weekly', percent_per_step: 20, step_interval_days: 7 }));
-      expect(points()).toBe(1);
+    const checkedRamp = (): string => document.querySelector<HTMLInputElement>('input[name="ramp-schedule"]:checked')!.value;
+    const customFields = (): string[] => ['ramp-step-percent', 'ramp-interval-days'].map(id => (document.getElementById(id) as HTMLInputElement).value);
+
+    test.each([
+      ['weekly 20% / 7d', { type: 'weekly', percent_per_step: 20, step_interval_days: 7 }, 'custom', ['20', '7'], 5],
+      ['monthly 5% / 30d', { type: 'monthly', percent_per_step: 5, step_interval_days: 30 }, 'custom', ['5', '30'], 20],
+      ['weekly 25% on a 14 day interval', { type: 'weekly', percent_per_step: 25, step_interval_days: 14 }, 'custom', ['25', '14'], 4],
+      ['monthly 10% on a 15 day interval', { type: 'monthly', percent_per_step: 10, step_interval_days: 15 }, 'custom', ['10', '15'], 10],
+      ['weekly 25% / 7d', { type: 'weekly', percent_per_step: 25, step_interval_days: 7 }, 'weekly-25pct', null, 4],
+      ['monthly 10% / 30d', { type: 'monthly', percent_per_step: 10, step_interval_days: 30 }, 'monthly-10pct', null, 10],
+      ['immediate', { type: 'immediate', percent_per_step: 100, step_interval_days: 0 }, 'immediate', null, 1],
+    ])('Edit prefills a stored %s ramp as %s (#1156)', async (_name, ramp, radio, fields, count) => {
+      await openEdit(backendPlan(ramp));
+      expect(checkedRamp()).toBe(radio);
+      if (fields) expect(customFields()).toEqual(fields);
+      expect(points()).toBe(count);
     });
 
     test('Edit with absent coverage shows the validation message and no points', async () => {
diff --git a/frontend/src/plans.ts b/frontend/src/plans.ts
index 55398c8a7..e9365d926 100644
--- a/frontend/src/plans.ts
+++ b/frontend/src/plans.ts
@@ -1272,6 +1272,19 @@ function openPlanForm(modal: HTMLElement, restartsFromToday = false): void {
   openModal(modal, { initialFocus: '#plan-name', onClose: () => { disposePlanEditor?.(); disposePlanEditor = undefined; } });
 }
 
+// Presets mirror config.PresetRampSchedules; any other stored ramp is shown as
+// custom so Edit never rewrites it to a different schedule on Save (#1156).
+const PRESET_RAMPS: ReadonlyArray<{ value: string; type: string; percent: number; intervalDays: number }> = [
+  { value: 'weekly-25pct', type: 'weekly', percent: 25, intervalDays: 7 },
+  { value: 'monthly-10pct', type: 'monthly', percent: 10, intervalDays: 30 },
+];
+
+function rampRadioValue(ramp: { type?: string; percent_per_step?: number; step_interval_days?: number }): string {
+  if (ramp.type === 'immediate') return 'immediate';
+  const preset = PRESET_RAMPS.find(p => p.type === ramp.type && p.percent === ramp.percent_per_step && p.intervalDays === ramp.step_interval_days);
+  return preset ? preset.value : 'custom';
+}
+
 // editPlan loads the plan and opens the edit modal pre-filled. Returns true
 // when the modal opened, false when the plan could not be loaded (e.g. it was
 // deleted or is no longer accessible). Callers that render the plan in a list
@@ -1284,15 +1297,7 @@ async function editPlan(planId: string): Promise<boolean> {
     const info = extractPlanInfo(backendPlan);
     const rampSchedule = backendPlan.ramp_schedule || { type: 'immediate', percent_per_step: 100, step_interval_days: 0 };
 
-    // Map ramp schedule type to frontend value
-    let rampValue = 'immediate';
-    if (rampSchedule.type === 'weekly' && rampSchedule.percent_per_step === 25) {
-      rampValue = 'weekly-25pct';
-    } else if (rampSchedule.type === 'monthly' && rampSchedule.percent_per_step === 10) {
-      rampValue = 'monthly-10pct';
-    } else if (rampSchedule.type === 'custom' || (rampSchedule.type !== 'immediate' && rampSchedule.type !== 'weekly' && rampSchedule.type !== 'monthly')) {
-      rampValue = 'custom';
-    }
+    const rampValue = rampRadioValue(rampSchedule);
 
     // Get payment option from services and normalize for provider.
     // H-5: do not pre-select 'no-upfront' when the payment field is absent.
diff --git a/frontend/tests-e2e/plan-schedule-preview.spec.ts b/frontend/tests-e2e/plan-schedule-preview.spec.ts
index bcbd9a22f..dbd2cf126 100644
--- a/frontend/tests-e2e/plan-schedule-preview.spec.ts
+++ b/frontend/tests-e2e/plan-schedule-preview.spec.ts
@@ -134,6 +134,14 @@ for (const [width, height] of [[1440, 900], [1280, 900], [1280, 768], [1024, 900
       expect(footerBox.y + footerBox.height).toBeLessThanOrEqual(page.viewportSize()!.height);
       await page.locator('#close-plan-modal-btn').click();
     }
+    plan.ramp_schedule = { type: 'weekly', current_step: 0, total_steps: 5, step_interval_days: 7, percent_per_step: 20 };
+    await page.reload();
+    await page.locator('[data-action="edit-plan"][data-id="draft-plan"]').click();
+    await expect(page.locator('input[name="ramp-schedule"][value="custom"]')).toBeChecked();
+    await expect(page.locator('#ramp-step-percent')).toHaveValue('20');
+    await expect(page.locator('#ramp-interval-days')).toHaveValue('7');
+    await expect(page.locator('#plan-editor-panel [data-preview-step]')).toHaveCount(5);
+    await page.locator('#close-plan-modal-btn').click();
     await page.locator('#new-plan-btn').click();
     const dense = page.locator('#plan-editor-panel'), scroll = dense.locator('.schedule-preview-scroll');
     await page.locator('#plan-modal label.ramp-option').filter({ hasText: 'Define your own schedule' }).click();