feat(photos): Photos-ready lineup after Calculate (#64)

Add buildPhotosReadyLineup (clean cal → overlay → batch inventory PNGs
in capture order, plus empty-mask/floor error slots). MeasurePanel
switches to a Photos ready end screen with Milestone 1 numbers and the
inventory PNG lineup; Back still returns to Length axis.

frontend/src/capture/MeasurePanel.svelte

@@ -1,8 +1,14 @@
 <script lang="ts">
+  import { onDestroy } from 'svelte';
   import type { Capture } from './capture.types';
   import { inToEighths, eighthsToIn } from './capture.types';
   import { fmtEighths } from './session';
   import PhotoStage from './PhotoStage.svelte';
+  import {
+    buildPhotosReadyLineup,
+    photosReadyPngAlt,
+    type PhotosReadyLineupItem,
+  } from './photosReadyLineup';
 
   export let state: Extract<Capture, { k: 'measure' }>;
   export let setLength: (e: number) => void;
@@ -15,6 +21,32 @@
   let lengthIn = state.lengthEighths === 0 ? '' : String(eighthsToIn(state.lengthEighths));
   let thicknessIn = state.thicknessEighths === 0 ? '' : String(eighthsToIn(state.thicknessEighths));
 
+  let lineupUrls: string[] = [];
+  let lineupItems: PhotosReadyLineupItem[] = [];
+
+  $: photosReady = !!state.results;
+  $: {
+    for (const u of lineupUrls) URL.revokeObjectURL(u);
+    lineupUrls = [];
+    if (state.results) {
+      lineupItems = buildPhotosReadyLineup({
+        inventoryPng: state.results.inventoryPng,
+        overlayPng: state.results.overlayPng,
+        batchApply: state.batchApply,
+        sourceBelowFloor: state.results.sourceBelowFloor,
+      });
+      lineupUrls = lineupItems.map((it) =>
+        it.kind === 'png' ? URL.createObjectURL(it.blob) : '',
+      );
+    } else {
+      lineupItems = [];
+    }
+  }
+
+  onDestroy(() => {
+    for (const u of lineupUrls) URL.revokeObjectURL(u);
+  });
+
   const positiveInches = (raw: string): number | null => {
     const inches = Number.parseFloat(raw);
     return Number.isFinite(inches) && inches > 0 ? inches : null;
@@ -46,7 +78,9 @@
 </script>
 
 <section class="panel">
-  <h1>Measure</h1>
+  <h1>{photosReady ? 'Photos ready' : 'Measure'}</h1>
+
+  {#if !photosReady}
     <PhotoStage
       blob={state.source.blob}
       bbox={state.axis.bbox}
@@ -97,9 +131,8 @@
         {calcBusy ? 'Calculating…' : 'Calculate'}
       </button>
     </div>
-
+  {:else if state.results}
-  {#if state.results}
+    <div class="results" aria-label="Photos ready">
-    <div class="results">
       <div class="nums">
         <div><span>Widths</span><span>{fmtEighths(state.results.widths.min)} – {fmtEighths(state.results.widths.max)} (avg {fmtEighths(state.results.widths.avg)})</span></div>
         <div><span>Sqft</span><span>{state.results.sqft.toFixed(2)}</span></div>
@@ -109,12 +142,42 @@
       {#if state.results.sourceBelowFloor}
         <div class="warn">Source is below the 800px floor for the inventory PNG. Retake a larger photo.</div>
       {/if}
-      {#if pngUrl && !state.results.sourceBelowFloor}
+
+      <ol class="lineup" aria-label="Inventory PNG lineup">
+        {#each lineupItems as item, i (i)}
+          {#if item.kind === 'png'}
+            <li class="lineup-item png">
+              <img src={lineupUrls[i]} alt={photosReadyPngAlt(item)} />
+              <span class="role">
+                {#if item.role === 'calibration'}
+                  Clean calibration
+                {:else if item.role === 'overlay'}
+                  Dimension overlay
+                {:else}
+                  Batch photo {(item.batchIndex ?? 0) + 1}
+                {/if}
+              </span>
+            </li>
+          {:else}
+            <li class="lineup-item error" role="alert">
+              <span class="err-title">Photo {item.batchIndex + 1} failed</span>
+              <span class="err-msg">{item.message}</span>
+            </li>
+          {/if}
+        {/each}
+      </ol>
+
+      <!-- Legacy single-PNG fallback only when lineup helper yielded nothing but pngUrl exists -->
+      {#if lineupItems.length === 0 && pngUrl && !state.results.sourceBelowFloor}
         <div class="png-wrap">
           <img src={pngUrl} alt="Inventory PNG" />
         </div>
       {/if}
     </div>
+
+    <div class="row">
+      <button type="button" class="ghost" on:click={back}>Back</button>
+    </div>
   {/if}
 </section>
 
@@ -136,11 +199,29 @@
   }
   .primary:disabled { background: #333; color: #777; }
   .ghost { flex: 1; padding: 14px; border-radius: 10px; border: 1px solid #444; background: transparent; color: #ccc; }
-  .results { margin-top: 20px; }
+  .results { margin-top: 8px; }
   .nums { display: flex; flex-direction: column; gap: 8px; }
   .nums div { display: flex; justify-content: space-between; border-bottom: 1px solid #2a2a2a; padding-bottom: 6px; }
   .nums span:first-child { color: #aaa; }
   .warn { color: #ffb4a2; margin-top: 12px; font-size: 0.9rem; }
+  .lineup {
+    list-style: none; padding: 0; margin: 16px 0 0;
+    display: flex; flex-direction: column; gap: 14px;
+  }
+  .lineup-item.png {
+    text-align: center;
+    background-image: linear-gradient(45deg,#ccc 25%,transparent 25%),linear-gradient(-45deg,#ccc 25%,transparent 25%),linear-gradient(45deg,transparent 75%,#ccc 75%),linear-gradient(-45deg,transparent 75%,#ccc 75%);
+    background-size: 16px 16px; background-position: 0 0,0 8px,8px -8px,-8px 0;
+    background-color: #eee; border-radius: 8px; padding: 8px;
+  }
+  .lineup-item.png img { max-width: 100%; border-radius: 4px; display: block; margin: 0 auto; }
+  .role { display: block; margin-top: 8px; font-size: 0.85rem; color: #222; font-weight: 600; }
+  .lineup-item.error {
+    border: 1px solid #8a3a2a; background: #2a1512; border-radius: 8px;
+    padding: 12px 14px; display: flex; flex-direction: column; gap: 4px;
+  }
+  .err-title { color: #ffb4a2; font-weight: 700; font-size: 0.95rem; }
+  .err-msg { color: #e8cfc8; font-size: 0.9rem; }
   .png-wrap { margin-top: 16px; text-align: center; background-image: linear-gradient(45deg,#ccc 25%,transparent 25%),linear-gradient(-45deg,#ccc 25%,transparent 25%),linear-gradient(45deg,transparent 75%,#ccc 75%),linear-gradient(-45deg,transparent 75%,#ccc 75%); background-size: 16px 16px; background-position: 0 0,0 8px,8px -8px,-8px 0; background-color: #eee; border-radius: 8px; padding: 8px; }
   .png-wrap img { max-width: 100%; border-radius: 4px; }
 </style>

frontend/src/capture/photosReadyLineup.ts

@@ -0,0 +1,75 @@
+import type { BatchPhotoResult } from './capture.types';
+
+/** One slot in the Photos-ready end screen (#64 / docs/PHOTOS.md). */
+export type PhotosReadyLineupItem =
+  | {
+      kind: 'png';
+      role: 'calibration' | 'overlay' | 'batch';
+      blob: Blob;
+      /** Capture-order index for non-calibration batch inventory PNGs. */
+      batchIndex?: number;
+    }
+  | {
+      kind: 'error';
+      batchIndex: number;
+      message: string;
+    };
+
+export interface PhotosReadyLineupInput {
+  inventoryPng?: Blob | null;
+  overlayPng?: Blob | null;
+  batchApply?: BatchPhotoResult[] | null;
+  /** When true, omit the clean calibration PNG (M1 floor warn path). */
+  sourceBelowFloor?: boolean;
+}
+
+/**
+ * Build the Photos-ready lineup:
+ * 1. Clean calibration inventory PNG
+ * 2. Dimension-overlay copy
+ * 3. Other batch inventory PNGs in capture order (batchApply, skip cal null)
+ *    with error slots for empty mask / floor failures.
+ */
+export function buildPhotosReadyLineup(
+  input: PhotosReadyLineupInput,
+): PhotosReadyLineupItem[] {
+  const items: PhotosReadyLineupItem[] = [];
+  const { inventoryPng, overlayPng, batchApply, sourceBelowFloor } = input;
+
+  if (inventoryPng && !sourceBelowFloor) {
+    items.push({ kind: 'png', role: 'calibration', blob: inventoryPng });
+  }
+  if (overlayPng) {
+    items.push({ kind: 'png', role: 'overlay', blob: overlayPng });
+  }
+
+  if (batchApply) {
+    for (let i = 0; i < batchApply.length; i++) {
+      const slot = batchApply[i];
+      if (slot === null) continue; // calibration lives in results.inventoryPng
+      if (slot.status === 'ok') {
+        items.push({
+          kind: 'png',
+          role: 'batch',
+          blob: slot.inventoryPng,
+          batchIndex: i,
+        });
+      } else {
+        items.push({
+          kind: 'error',
+          batchIndex: i,
+          message: slot.message,
+        });
+      }
+    }
+  }
+
+  return items;
+}
+
+export function photosReadyPngAlt(item: Extract<PhotosReadyLineupItem, { kind: 'png' }>): string {
+  if (item.role === 'calibration') return 'Calibration inventory PNG';
+  if (item.role === 'overlay') return 'Calibration dimension-overlay PNG';
+  const n = (item.batchIndex ?? 0) + 1;
+  return `Batch inventory PNG ${n}`;
+}