merge: a11y evidence via ariaSnapshot (PR #9)

apps/api/src/capture/capture.ts

@@ -21,6 +21,7 @@ export interface CapturedPage {
     value: string | null;
     children?: unknown[];
   } | null;
+  ariaSnapshot: string | null;
   har: {
     entries: { url: string; method: string; status: number; mimeType: string | null; size: number | null }[];
     entryCount: number;
@@ -95,10 +96,11 @@ export function buildEvidence(targetId: string, page: CapturedPage): CaptureEvid
       requests: page.networkRequests,
     }, tool),
   ];
-  if (page.accessibilityTree) {
+  if (page.accessibilityTree || page.ariaSnapshot) {
     evidence.push(
       record(targetId, page.finalUrl, "accessibility", {
-        tree: page.accessibilityTree,
+        tree: page.accessibilityTree ?? undefined,
+        ariaSnapshot: page.ariaSnapshot ?? undefined,
       }, tool),
     );
   }
@@ -234,8 +236,11 @@ export async function capturePage(
       // Screenshot failure is an evidence gap, not a capture failure.
       screenshotBase64 = null;
     }
-    // Accessibility tree (measured; null on failure = explicit evidence gap).
+    // Accessibility evidence (measured). Legacy page.accessibility first
+    // (older runtimes), else ariaSnapshot on body (playwright >= 1.49).
+    // Failure = explicit evidence gap (null), never a capture failure.
     let accessibilityTree: CapturedPage["accessibilityTree"] = null;
+    let ariaSnapshot: string | null = null;
     try {
       const acc = (page as unknown as { accessibility?: { snapshot(): Promise<unknown> } })
         .accessibility;
@@ -243,6 +248,13 @@ export async function capturePage(
     } catch {
       accessibilityTree = null;
     }
+    if (!accessibilityTree) {
+      try {
+        ariaSnapshot = await page.locator("body").ariaSnapshot({ timeout: 5000 });
+      } catch {
+        ariaSnapshot = null;
+      }
+    }
     // HAR (measured; condensed to entry-level metadata).
     let har: CapturedPage["har"] = null;
     try {
@@ -269,6 +281,7 @@ export async function capturePage(
       ...captured,
       networkRequests,
       accessibilityTree,
+      ariaSnapshot,
       har,
       screenshotBase64,
     };