feat(ui): documents open in an almost-fullscreen modal instead of a new page — same-page overlay on chat + Sources, /document.html kept as the no-JS/direct-link fallback

frontend/sources.html

@@ -121,7 +121,44 @@
 
   <!-- Phase 19: the shared header module loads through the page script's
        own `import "./header.js"` — a hoisted import that is evaluated
-       before the page script body calls initSharedHeader() at boot. -->
+       before the page script body calls initSharedHeader() at boot.
+       Phase 26: markdown.js (the classic global renderMarkdown) loads
+       BEFORE the module script — the document modal renders md
+       documents through it on this page too. -->
+  <script src="assets/markdown.js"></script>
   <script type="module" src="/assets/sources.js"></script>
+
+  <!-- Phase 26: the almost-fullscreen document modal — SAME skeleton as
+       the chat page (index.html): Sources-table path links open documents
+       here (same-page overlay, no new tab) instead of navigating to
+       /document.html, which stays the no-JS / direct-link fallback,
+       unchanged. The page script fetches /api/documents/content and
+       renders into #doc-modal-content through the shared renderDocument
+       (document.js); the hidden attribute keeps the skeleton inert until
+       JS opens it. #doc-modal-open points at the same
+       /document.html?source=…&path=… URL the link carries, so the
+       dedicated page is always one click away. -->
+  <div class="doc-modal" id="doc-modal" hidden>
+    <div class="doc-modal-backdrop" id="doc-modal-backdrop" aria-hidden="true"></div>
+    <div class="doc-modal-panel" id="doc-modal-panel" role="dialog" aria-modal="true" aria-labelledby="doc-modal-title" aria-describedby="doc-modal-desc">
+      <header class="doc-modal-header">
+        <h2 class="doc-modal-title" id="doc-modal-title">Loading…</h2>
+        <div class="doc-modal-actions">
+          <a class="doc-modal-open" id="doc-modal-open" target="_blank" rel="noopener" hidden aria-label="Open in full page">
+            <svg aria-hidden="true" viewBox="0 0 24 24" fill="none" stroke="currentColor" stroke-width="1.7" stroke-linecap="round"><path d="M18 13v6a2 2 0 0 1-2 2H5a2 2 0 0 1-2-2V8a2 2 0 0 1 2-2h6"/><path d="M15 3h6v6"/><path d="M10 14 21 3"/></svg>
+            <span>Full page</span>
+          </a>
+          <button type="button" class="doc-modal-close" id="doc-modal-close" aria-label="Close document">
+            <svg aria-hidden="true" viewBox="0 0 24 24" fill="none" stroke="currentColor" stroke-width="1.7" stroke-linecap="round"><path d="M18 6 6 18M6 6l12 12"/></svg>
+          </button>
+        </div>
+      </header>
+      <div class="doc-modal-meta" id="doc-modal-meta" aria-live="polite"></div>
+      <p class="visually-hidden" id="doc-modal-desc" role="status">Document content is loading.</p>
+      <main class="doc-modal-content" id="doc-modal-content" tabindex="-1">
+        <p class="doc-modal-loading" role="status">Loading document…</p>
+      </main>
+    </div>
+  </div>
 </body>
 </html>