diff --git a/public/css/assistant.css b/public/css/assistant.css
index 9a31ffd4..35940968 100644
--- a/public/css/assistant.css
+++ b/public/css/assistant.css
@@ -123,7 +123,9 @@
 .assistant-image-modal-card img { max-width:100%; max-height:92vh; border-radius:14px; background:white; box-shadow:0 24px 80px rgba(0,0,0,.35); }
 .assistant-image-modal-close { position:absolute; top:8px; right:8px; z-index:1; width:38px; height:38px; border:0; border-radius:999px; background:white; color:var(--g800); font-size:24px; line-height:1; cursor:pointer; box-shadow:var(--shadow); }
 .assistant-image-modal-cancel { justify-self:center; border:0; border-radius:999px; background:white; color:var(--g800); font-weight:700; padding:9px 14px; box-shadow:var(--shadow); cursor:pointer; }
-.assistant-sources { padding:10px 12px; display:grid; gap:8px; flex:1 1 auto; min-height:0; overflow-y:auto; }
+/* One column capped at the panel's width: an auto grid column grows to its
+   widest unbreakable content, so a long file name pushed every card off-screen. */
+.assistant-sources { padding:10px 12px; display:grid; grid-template-columns:minmax(0,1fr); gap:8px; flex:1 1 auto; min-height:0; overflow-y:auto; overflow-x:hidden; }
 .assistant-saved-chats { flex:1 1 auto; overflow-y:auto; min-height:0; padding:10px 12px; display:flex; flex-direction:column; gap:8px; }
 /* Open WebUI-style recency headings above each run of chats. */
 /* Composed empty state: a title, one status pill and the composer — nothing
@@ -158,7 +160,9 @@
 .assistant-saved-chat-title { font-size:13px; font-weight:500; color:var(--g800); line-height:1.35; display:block; white-space:nowrap; overflow:hidden; text-overflow:ellipsis; }
 .assistant-saved-chat-meta { font-size:11px; color:var(--g500); display:block; white-space:nowrap; overflow:hidden; text-overflow:ellipsis; }
 .assistant-save-actions { display:flex; gap:6px; flex-wrap:wrap; }
-.assistant-source { border:1px solid var(--g200); border-radius:10px; padding:10px 12px; background:white; box-shadow:var(--shadow); font-size:12px; line-height:1.5; transition:border-color .12s ease; }
+/* Long names break onto new lines instead of running past the card
+   (word-break is the fallback for iOS Safari before 15.4). */
+.assistant-source { min-width:0; overflow-wrap:anywhere; word-break:break-word; border:1px solid var(--g200); border-radius:10px; padding:10px 12px; background:white; box-shadow:var(--shadow); font-size:12px; line-height:1.5; transition:border-color .12s ease; }
 .assistant-source:hover { border-color:var(--blue-light); }
 .assistant-source:target { border-color:var(--blue); box-shadow:0 0 0 3px var(--blue-light); }
 .assistant-source strong { color:var(--g800); }
@@ -211,7 +215,10 @@
     border:none; box-shadow:none; border-radius:0; }
   .assistant-side .card-header { flex:0 0 auto; }
   /* The band is fixed height, so the list inside it is what scrolls. */
-  .assistant-sources { flex:1 1 auto; min-height:0; overflow-y:auto; -webkit-overflow-scrolling:touch;
+  /* On a touchscreen the list is one smooth vertical scroll: no sideways pan,
+     and no excerpt scrolling inside it. */
+  .assistant-source-excerpt { max-height:none; overflow:visible; }
+  .assistant-sources { flex:1 1 auto; min-height:0; overflow-y:auto; overflow-x:hidden; touch-action:pan-y; -webkit-overflow-scrolling:touch;
     padding-bottom:calc(12px + env(safe-area-inset-bottom)); }
   /* Slim toolbar: icon-only actions in one row */
   /* Saved chats: a fixed drawer overlaying the chat */
diff --git a/test/assistant-mobile.test.js b/test/assistant-mobile.test.js
index 6e878ba7..0771576e 100644
--- a/test/assistant-mobile.test.js
+++ b/test/assistant-mobile.test.js
@@ -140,3 +140,15 @@ test('on a phone the menu follows the view: chat history in the assistant', () =
   assert.match(mobile, /#assistant-saved-chats \{ flex:1 1 auto; min-height:0; overflow-y:auto;/, 'the chat list does');
   assert.match(mobile, /\.assistant-drawer-close \{ display:none !important; \}/, 'one close control, the « in the head row');
 });
+
+test('source cards fit the phone: long names wrap, nothing scrolls sideways or inside', () => {
+  const css = read('public/css/assistant.css');
+  // An auto grid column grew to the longest unbroken file name, so every card
+  // ran off the right edge of an iPhone.
+  assert.match(css, /^\.assistant-sources \{[^}]*grid-template-columns:minmax\(0,1fr\);[^}]*overflow-x:hidden;/m);
+  assert.match(css, /^\.assistant-source \{ min-width:0; overflow-wrap:anywhere; word-break:break-word;/m,
+    'long names break onto new lines, with the pre-15.4 Safari fallback');
+  const mobile = css.slice(css.indexOf('@media (max-width: 640px)'));
+  assert.match(mobile, /\.assistant-source-excerpt \{ max-height:none; overflow:visible; \}/, 'no scroll box inside the scrolling list');
+  assert.match(mobile, /\.assistant-sources \{[^}]*overflow-x:hidden; touch-action:pan-y;/, 'and no sideways pan');
+});