feat(agent): conversation par paire + entrée médiée + pivot terminal/MCP

Coeur inter-agents consolidé et surface front réalignée sur la décision
"terminal natif PTY, pas d'UI chat" (Option 1).

Domaine
- nouveaux modules conversation, mailbox, input, fileguard (ports + types)
- orchestrator/profile/events étendus (conversation par paire, FIFO)

Application / Infrastructure
- orchestrator/service + context_guard : sérialisation FIFO par agent,
  garde RW mémoire/contexte, dispatch ask/reply
- adapters in-memory conversation / mailbox / input / fileguard
- registry session + lifecycle agent durcis (1 agent = 1 session vivante)
- outils MCP idea_* alignés sur le nouveau dispatch

Frontend
- MediatedInput + useAgentBusy : entrée utilisateur médiée par IdeA,
  terminal = vue sortie inchangée
- suppression de la vue chat structurée (AgentChatView) — abandonnée
- adapter input + ports mis à jour

Divers
- .ideai/ : mémoire projet + briefs de cadrage versionnés ;
  requests/ runtime ignoré ; agents projet réels (DevBackend/DevFrontend/QA)

Tests : Rust (domain/application/infrastructure/app-tauri) + front (346) verts.

Co-Authored-By: Claude Opus 4.8 <noreply@anthropic.com>

frontend/src/features/terminals/TerminalView.tsx

@@ -3,7 +3,11 @@
  * {@link TerminalGateway} port (or a custom opener), and fits it to its container:
  *
  * - PTY output (gateway `onData`) → `term.write(bytes)`.
- * - xterm `onData` (keystrokes) → `handle.write(bytes)`.
+ * - xterm `onData` (keystrokes) → `handle.write(bytes)` **only for a plain
+ *   (non-agent) cell** (a raw shell). In **agent mode** (`agentMode`, lot F2,
+ *   cadrage §4.2) keystrokes are NOT written to the PTY: input is mediated by
+ *   IdeA through {@link MediatedInput}. The PTY **output** path stays live and
+ *   INCHANGED in both modes (xterm is always the raw output view).
  * - container resize (fit addon) → `handle.resize(rows, cols)`.
  *
  * Pure presentation: it only knows the port, never `invoke()`/`Channel`
@@ -71,6 +75,15 @@ interface TerminalViewProps {
    * reattach (the id is already known).
    */
   onSessionId?: (sessionId: string) => void;
+  /**
+   * Agent mode (lot F2, cadrage §4.2). When `true` the cell hosts an agent, so
+   * keystrokes (`term.onData`) are **not** forwarded to the PTY — input is
+   * mediated by IdeA through {@link MediatedInput} rendered under the terminal.
+   * The PTY **output** stays live and unchanged (xterm remains the raw output
+   * view). When `false`/absent the cell is a plain shell: keystrokes go straight
+   * to the PTY (current behaviour). Defaults to `false`.
+   */
+  agentMode?: boolean;
 }
 
 export function TerminalView({
@@ -79,6 +92,7 @@ export function TerminalView({
   reattach,
   sessionId,
   onSessionId,
+  agentMode = false,
 }: TerminalViewProps) {
   const { terminal } = useGateways();
   const containerRef = useRef<HTMLDivElement | null>(null);
@@ -100,6 +114,8 @@ export function TerminalView({
   onSessionIdRef.current = onSessionId;
   const terminalRef = useRef(terminal);
   terminalRef.current = terminal;
+  const agentModeRef = useRef(agentMode);
+  agentModeRef.current = agentMode;
 
   useEffect(() => {
     const container = containerRef.current;
@@ -135,9 +151,14 @@ export function TerminalView({
     let handle: TerminalHandle | null = null;
     const encoder = new TextEncoder();
 
-    // Buffer keystrokes that arrive before the PTY finished opening.
+    // Keystroke → PTY path. In **agent mode** (F2) keystrokes are mediated by
+    // IdeA (MediatedInput) and must NOT reach the PTY here; we drop them so the
+    // raw terminal is output-only for the human. In **plain mode** keystrokes go
+    // straight to the PTY (raw shell), buffering any that arrive before the PTY
+    // finished opening. The output path below is unchanged in both modes.
     let pending = "";
     const onKey = term.onData((data) => {
+      if (agentModeRef.current) return;
       if (handle) void handle.write(encoder.encode(data));
       else pending += data;
     });