diff --git a/frontend/src/create/review/Review.svelte b/frontend/src/create/review/Review.svelte
index 5df62c0..081f9fb 100644
--- a/frontend/src/create/review/Review.svelte
+++ b/frontend/src/create/review/Review.svelte
@@ -147,6 +147,10 @@
     role: 'calibration' | 'overlay' | 'batch';
     isCalibration: boolean;
     kept: boolean;
+    /** True for the mandatory photos (clean calibration + dimension-overlay
+        copy). Their keep checkbox is checked and disabled — the owner cannot
+        remove them (REVIEW-5 requires both). */
+    required: boolean;
     original: Blob;
     processed: Blob | null;
     url: string;
@@ -197,6 +201,10 @@
           id: r.id,
           role,
           isCalibration: r.is_calibration === 1,
+          // Mandatory: the clean calibration photo and the dimension-overlay
+          // copy. REVIEW-5 requires both to ship, so their keep control is
+          // checked + disabled (the owner can't remove them).
+          required: role === 'calibration' || role === 'overlay',
           kept: true,
           original: blob ?? new Blob(),
           processed: blob ?? null,
@@ -219,7 +227,12 @@
   // Whole-card tap = keep/remove toggle. A real drag (>6px) reorders and does NOT
   // toggle keep/remove — the threshold lives in the pointer handlers below.
   function toggleKeep(id: string) {
-    photos = photos.map((p) => (p.id === id ? { ...p, kept: !p.kept } : p));
+    photos = photos.map((p) => {
+      if (p.id !== id) return p;
+      // Mandatory photos (clean cal + dimension-overlay) can't be removed.
+      if (p.required) return p;
+      return { ...p, kept: !p.kept };
+    });
     lineupDirty = true;
   }
 
@@ -524,12 +537,15 @@
               class="pcard"
               class:kept={p.kept}
               class:primary={p.id === primaryId}
+              class:required={p.required}
               data-testid="photo-card"
               data-primary={p.id === primaryId ? 'true' : ''}
+              data-required={p.required ? 'true' : ''}
               role="button"
               tabindex="0"
-              aria-pressed={p.kept}
-              aria-label="{roleLabel(p.role)}{p.kept ? ', kept' : ', removed'}"
+              aria-pressed={p.required ? true : p.kept}
+              aria-disabled={p.required ? 'true' : 'false'}
+              aria-label="{p.required ? 'Required: ' : ''}{roleLabel(p.role)}{p.required ? ' (cannot be removed)' : (p.kept ? ', kept' : ', removed')}"
               draggable="true"
               on:click={() => toggleKeep(p.id)}
               on:keydown={(e) => { if (e.key === 'Enter' || e.key === ' ') { e.preventDefault(); toggleKeep(p.id); } }}
@@ -542,7 +558,9 @@
                 <span class="ph-pri">PRIMARY</span>
               {/if}
               <span class="ph-seq" aria-hidden="true">{i + 1}</span>
-              <span class="ph-keep" aria-hidden="true"></span>
+              <!-- Keep checkbox: always checked for required photos; a disabled
+                   glyph (no check) when a batch photo is removed. -->
+              <span class="ph-keep" class:required={p.required} aria-hidden="true"></span>
             </div>
           {/each}
         </div>
@@ -810,5 +828,14 @@
   .ph-keep { position: absolute; top: 6px; left: 6px; width: 16px; height: 16px; border: 2px solid #fff; border-radius: 3px; background: rgba(0,0,0,.5); pointer-events: none; }
   .pcard.kept .ph-keep { background: #00e5ff; border-color: #00e5ff; }
   .pcard.kept .ph-keep::after { content: ''; position: absolute; left: 4px; top: 1px; width: 4px; height: 8px; border: solid #002; border-width: 0 2px 2px 0; transform: rotate(45deg); }
+  /* Mandatory photos (clean cal + dimension-overlay): the keep checkbox is
+     checked AND disabled — it can't be unchecked, and a small lock glyph
+     signals "required, cannot be removed". The card keeps full opacity even
+     though it's always kept, and the cursor shows it's not a remove target. */
+  .pcard.required { border-color: #2a2a2a; }
+  .pcard.required .ph-keep { background: #00e5ff; border-color: #00e5ff; }
+  .pcard.required .ph-keep::after { content: ''; position: absolute; left: 4px; top: 1px; width: 4px; height: 8px; border: solid #002; border-width: 0 2px 2px 0; transform: rotate(45deg); }
+  .pcard.required .ph-keep::before { content: ''; position: absolute; left: 2.5px; top: 5px; width: 7px; height: 5px; border: 1.5px solid #002; border-radius: 1px; }
+  .pcard.required { cursor: default; }
   .ph-nudge { color: #e8a; font-size: .74rem; margin: 8px 0 0; }
 </style>
diff --git a/frontend/tests/e2e/review-photo-strip.spec.ts b/frontend/tests/e2e/review-photo-strip.spec.ts
index 1473875..6f375d1 100644
--- a/frontend/tests/e2e/review-photo-strip.spec.ts
+++ b/frontend/tests/e2e/review-photo-strip.spec.ts
@@ -212,18 +212,30 @@ test.describe('M3 Review photo strip (#90)', () => {
     const bgImage = await cards.nth(0).evaluate((el) => getComputedStyle(el).backgroundImage);
     expect(bgImage).toContain('45deg');
 
-    // Remove the primary (cal) → primary auto-promotes to the next leftmost (ov).
-    await cards.nth(0).click();
-    await expect(cards.nth(0)).toHaveAttribute('aria-pressed', 'false');
-    await expect(cards.nth(1)).toHaveAttribute('data-primary', 'true');
-    // Minimum nudge: cal + batch kept, but overlay still present → only cal missing.
-    await expect(page.getByTestId('lineup-nudge')).toBeVisible();
-    await expect(page.getByTestId('lineup-nudge')).toContainText('clean photo');
+    // Mandatory photos: the clean calibration (seq 1) and the dimension-overlay
+    // copy (seq 2) are required — their keep checkbox is checked AND disabled.
+    await expect(cards.nth(0)).toHaveAttribute('data-required', 'true');
+    await expect(cards.nth(1)).toHaveAttribute('data-required', 'true');
+    await expect(cards.nth(2)).toHaveAttribute('data-required', '');
+    await expect(cards.nth(0)).toHaveAttribute('aria-pressed', 'true');
+    await expect(cards.nth(1)).toHaveAttribute('aria-pressed', 'true');
 
-    // Re-add the cal (the original re-check bug) → it's back to the left = primary.
-    await cards.nth(0).click();
+    // Tapping a mandatory photo is a no-op: it stays checked + primary (can't remove).
+    // The card is aria-disabled, so force the click to exercise the handler directly.
+    await cards.nth(0).click({ force: true });
     await expect(cards.nth(0)).toHaveAttribute('aria-pressed', 'true');
     await expect(cards.nth(0)).toHaveAttribute('data-primary', 'true');
+    // No minimum nudge — both required photos are kept by construction.
+    await expect(page.getByTestId('lineup-nudge')).toHaveCount(0);
+
+    // Remove the OPTIONAL batch photo (index 2) → it un-keeps; required stay kept.
+    await cards.nth(2).click();
+    await expect(cards.nth(2)).toHaveAttribute('aria-pressed', 'false');
+    // Primary is still the leftmost required (cal, index 0).
+    await expect(cards.nth(0)).toHaveAttribute('data-primary', 'true');
+    // Re-add the batch photo.
+    await cards.nth(2).click();
+    await expect(cards.nth(2)).toHaveAttribute('aria-pressed', 'true');
     await expect(page.getByTestId('lineup-nudge')).toHaveCount(0);
 
     // Drag the batch photo (index 2) to the front → it becomes the primary.
@@ -259,20 +271,29 @@ test.describe('M3 Review photo strip (#90)', () => {
     expect(seqs).toEqual([1, 2, 3]);
   });
 
-  test('removing a photo persists a DELETE and blocks publish when the minimum is broken', async ({ page }) => {
+  test('required photos guarantee the minimum; removing an OPTIONAL batch persists a DELETE', async ({ page }) => {
     const mock = await mockApi(page);
     await reachReview(page);
     const cards = page.getByTestId('photo-card');
 
-    // Remove the overlay (seq 2) → minimum broken (no overlay).
-    await cards.nth(1).click();
-    await expect(cards.nth(1)).toHaveAttribute('aria-pressed', 'false');
-    await expect(page.getByTestId('lineup-nudge')).toContainText('overlay');
+    // The clean calibration + dimension-overlay are mandatory and always kept,
+    // so the submission minimum can never be broken — publish is never lineup-blocked.
+    await expect(page.getByTestId('lineup-nudge')).toHaveCount(0);
 
-    // Complete the rest of the form; the slab fields are ready but the lineup is not.
+    // Removing an OPTIONAL batch photo is allowed and persists a DELETE.
+    await cards.nth(2).click();
+    await expect(cards.nth(2)).toHaveAttribute('aria-pressed', 'false');
+    // Still no nudge: both required photos remain kept.
+    await expect(page.getByTestId('lineup-nudge')).toHaveCount(0);
+
+    // Complete the rest of the form; the lineup is valid (required photos kept).
     await completeForReady(page);
-    await expect(page.getByTestId('ready-status')).toContainText(/Not ready|remaining/);
-    // Continue is blocked by the lineup minimum even though the fields are set.
-    await expect(page.getByTestId('continue-publish')).toBeDisabled();
+    await expect(page.getByTestId('ready-status')).toContainText('Ready to publish', { timeout: 15000 });
+    await expect(page.getByTestId('continue-publish')).toBeEnabled();
+    await page.getByTestId('continue-publish').click();
+    await expect(page.getByTestId('publish-screen')).toBeVisible();
+
+    // The removed batch photo persisted as a DELETE; the required photos re-uploaded.
+    expect(mock.deletes).toEqual(['ph-b1']);
   });
 });