feat(assistant): #91 refonte Notion de la zone de discussion — question ancrée en haut, fil chronologique, étapes repliables, barre Copier/Ajouter

frontend/style.css

@@ -9434,22 +9434,30 @@ body.popup-mode .content-area {
 .bookslm-activity.done .bookslm-activity-spinner,
 .bookslm-activity.error .bookslm-activity-spinner { animation: none; border-top-color: currentColor; }
 @keyframes bookslm-spin { to { transform: rotate(360deg); } }
-.bookslm-messages { flex: 1; overflow-y: auto; padding: 16px; display: flex; flex-direction: column; gap: 12px; }
-/* The newest turn (the assistant's answer being written) is pinned to the
-   very top of the messages window via flex `order`, so a submitted post and
-   its live result stay visible regardless of auto-scroll and prior history. */
-.bookslm-msg { display: flex; flex-direction: column; gap: 4px; }
-.bookslm-msg.latest { order: -1; }
-.bookslm-msg-meta { font-size: 10px; color: var(--text-secondary); opacity: 0.85;
+/* Notion-style AI thread: only this zone scrolls; entries stack vertically
+   with generous spacing. The latest user post is anchored to the top of the
+   visible area on send (scrollIntoView block:start + scroll-margin). */
+.bookslm-messages { flex: 1; overflow-y: auto; padding: 20px 16px; display: flex;
+  flex-direction: column; gap: 24px; }
+.bookslm-msg { display: flex; flex-direction: column; gap: 4px; scroll-margin-top: 14px; }
+.bookslm-msg.user { align-self: flex-end; max-width: 80%; }
+.bookslm-msg.assistant { align-self: stretch; width: 100%; }
+.bookslm-msg-meta { font-size: 11px; color: var(--text-secondary); opacity: 0.75;
   padding: 0 2px; align-self: flex-start; user-select: none; }
-.bookslm-copy-btn { align-self: flex-end; font-size: 10px; padding: 2px 8px;
-  border-radius: 6px; border: 1px solid var(--border); background: var(--surface);
-  color: var(--text-secondary); cursor: pointer; opacity: 0; transition: opacity 0.15s; }
-.bookslm-msg:hover .bookslm-copy-btn { opacity: 1; }
-.bookslm-copy-btn:hover { color: var(--accent); border-color: var(--accent); }
-.bookslm-bubble { max-width: 85%; padding: 10px 14px; border-radius: 12px; font-size: 14px; line-height: 1.5; word-wrap: break-word; }
-.bookslm-bubble.user { align-self: flex-end; background: var(--accent); color: #fff; border-bottom-right-radius: 4px; }
-.bookslm-bubble.assistant { align-self: flex-start; background: var(--surface2); color: var(--text-primary); border-bottom-left-radius: 4px; }
+/* Hover-revealed action bar (Copier / Ajouter). */
+.bookslm-msg-actions { display: flex; gap: 6px; margin-top: 4px; opacity: 0;
+  transition: opacity 0.15s; }
+.bookslm-msg.user .bookslm-msg-actions { justify-content: flex-end; }
+.bookslm-msg:hover .bookslm-msg-actions,
+.bookslm-msg-actions:focus-within { opacity: 1; }
+.bookslm-msg-action { display: inline-flex; align-items: center; gap: 5px;
+  font-size: 11px; padding: 3px 9px; border-radius: 6px; border: 1px solid transparent;
+  background: transparent; color: var(--text-secondary); cursor: pointer; }
+.bookslm-msg-action:hover { background: var(--surface2); color: var(--text-primary);
+  border-color: var(--border); }
+.bookslm-bubble { max-width: 85%; padding: 10px 14px; border-radius: 18px; font-size: 14px; line-height: 1.5; word-wrap: break-word; }
+.bookslm-bubble.user { align-self: flex-end; background: var(--surface2); color: var(--text-primary); border-bottom-right-radius: 6px; }
+.bookslm-bubble.assistant { align-self: flex-start; background: transparent; padding: 0; width: 100%; max-width: 100%; color: var(--text-primary); }
 .bookslm-bubble.assistant code { background: rgba(0,0,0,0.2); padding: 1px 4px; border-radius: 3px; font-size: 0.9em; }
 .bookslm-bubble.assistant pre { background: rgba(0,0,0,0.3); padding: 10px; border-radius: 6px; overflow-x: auto; margin: 8px 0; }
 .bookslm-sources { display: flex; flex-wrap: wrap; gap: 4px; margin-top: 8px; }
@@ -9484,7 +9492,13 @@ body.popup-mode .content-area {
 /* Agent-mode toggle in the header. */
 .bookslm-header button.bookslm-btn-agent.active { color: var(--accent); background: var(--surface2); }
 /* Tool-call trace shown above an assistant answer (agent mode). */
-.bookslm-tool-trace { display: flex; flex-direction: column; gap: 2px; margin-bottom: 6px; }
+/* Agent tool calls collapse into a discreet “N steps” line (Notion-style). */
+.bookslm-tool-trace { margin: 0 0 8px; }
+.bookslm-tool-trace summary { font-size: 11px; color: var(--text-secondary);
+  cursor: pointer; user-select: none; list-style: none; }
+.bookslm-tool-trace summary::before { content: '> '; }
+.bookslm-tool-trace[open] summary { margin-bottom: 4px; }
+.bookslm-tool-trace .bookslm-tool-line { padding-left: 12px; }
 .bookslm-tool-line { font-size: 11px; color: var(--text-secondary); }
 .bookslm-tool-line.failed { color: #f87171; }
 /* Mutation confirmation card (two-step propose/apply). */