Add optional image field to PuzzleConfig for share/preview images

Per new PR review feedback, adding a placeholder capability for a
per-puzzle preview/share image, to eventually populate og:image/
twitter:image. Confirmed by investigation (per the review request) that
DCR has no site-wide default/fallback share image anywhere for pages
without one - frontend's MetaData.opengraphProperties/SimplePage only add
og:image via explicit per-page overrides, never a default. So an unset
image is expected to simply omit og:image/twitter:image, matching
existing sitewide behaviour, rather than needing a placeholder asset.

- src/model/puzzles/puzzleConfigs.ts: added an optional image?: string
  field to PuzzleConfig, documented as intentionally unset on every
  current registry entry - none of the 6 V0 games have a real, licensed
  preview image yet, and this commit deliberately does NOT invent
  placeholder image URLs for any of them. isValidPuzzleConfig updated to
  allow image being absent, but reject it if present-and-empty or
  whitespace-only (same validation style already used for description).
- src/model/puzzles/puzzleConfigs.test.ts: added tests confirming every
  current entry has no image set, that validatePuzzleConfigs does not
  throw when a valid non-empty image is present, and that it rejects an
  empty-string or whitespace-only image.

tsc --noEmit clean, eslint clean, 17/17 tests passing in this suite (4
new tests added).

Co-authored-by: Copilot App <223556219+Copilot@users.noreply.github.com>

Author: andresilva-guardian

dotcom-rendering/src/model/puzzles/puzzleConfigs.test.ts

@@ -92,6 +92,44 @@ describe('puzzleConfigs registry', () => {
 		).toThrow(TypeError);
 	});
 
+	it('allows every entry to have no image configured (the current state)', () => {
+		expect(
+			Object.values(puzzleConfigs).every(
+				(config) => config.image === undefined,
+			),
+		).toBe(true);
+	});
+
+	it('does not throw when an entry has a valid, non-empty image set', () => {
+		expect(() =>
+			validatePuzzleConfigs({
+				...puzzleConfigs,
+				wordiply: {
+					...puzzleConfigs.wordiply!,
+					image: 'https://example.com/wordiply.jpg',
+				},
+			}),
+		).not.toThrow();
+	});
+
+	it('rejects an entry with an empty-string image', () => {
+		expect(() =>
+			validatePuzzleConfigs({
+				...puzzleConfigs,
+				wordiply: { ...puzzleConfigs.wordiply!, image: '' },
+			}),
+		).toThrow(TypeError);
+	});
+
+	it('rejects an entry with a whitespace-only image', () => {
+		expect(() =>
+			validatePuzzleConfigs({
+				...puzzleConfigs,
+				wordiply: { ...puzzleConfigs.wordiply!, image: '   ' },
+			}),
+		).toThrow(TypeError);
+	});
+
 	describe('getPuzzleConfig', () => {
 		it('returns the config for a known slug', () => {
 			expect(getPuzzleConfig('sudoku-easy')?.puzzleGroup).toBe(

dotcom-rendering/src/model/puzzles/puzzleConfigs.ts

@@ -54,6 +54,18 @@ export interface PuzzleConfig {
 	 * only the slug swapped in.
 	 */
 	description: string;
+	/**
+	 * An optional, full preview/share image URL for this puzzle, used to
+	 * populate `og:image`/`twitter:image` in `render.puzzlePage.web.tsx`.
+	 * Deliberately optional and unset on every current registry entry - DCR
+	 * has no site-wide default/fallback share image for pages without one
+	 * (confirmed by investigation; see docs/puzzle-page.md), so an unset
+	 * `image` simply omits `og:image`/`twitter:image` entirely, matching
+	 * existing sitewide behaviour rather than needing a placeholder. Leave
+	 * unset until a real, licensed preview image is provided for a given
+	 * puzzle - do not invent a placeholder URL here.
+	 */
+	image?: string;
 }
 
 const amuseLabsUrlTemplate =
@@ -138,14 +150,15 @@ const isValidPuzzleConfig = (key: string, config: PuzzleConfig): boolean => {
 	if (!puzzleGroups.includes(config.puzzleGroup)) return false;
 	if (!config.iframe.provider || !config.iframe.urlTemplate) return false;
 	if (!config.description.trim()) return false;
+	if (config.image !== undefined && !config.image.trim()) return false;
 	return true;
 };
 
 /**
  * Fail fast if the registry itself is malformed (e.g. a mismatched slug key,
- * a missing/empty `iframe` config, or a missing/empty `description`). Run
- * once at module load so a bad registry entry surfaces immediately rather
- * than at request time.
+ * a missing/empty `iframe` config, a missing/empty `description`, or a
+ * present-but-empty `image`). Run once at module load so a bad registry
+ * entry surfaces immediately rather than at request time.
  */
 export const validatePuzzleConfigs = (
 	configs: Record<string, PuzzleConfig>,