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/ports/index.ts

@@ -31,7 +31,6 @@ import type {
   MemoryType,
   Project,
   ProfileAvailability,
-  ReplyChunk,
   ResumableAgent,
   Skill,
   SkillScope,
@@ -166,40 +165,6 @@ export interface AgentGateway {
     agentId: string,
     conversationId: string,
   ): Promise<ConversationDetails>;
-  /**
-   * Sends a prompt to a live **structured** (chat) session and streams the
-   * reply turn back through `onReply` (ARCHITECTURE §17.7, command `agent_send`).
-   * Each {@link ReplyChunk} is delivered as it arrives: `textDelta`s accumulate
-   * into the current turn, `toolActivity` shows tool badges, and the terminal
-   * `final` chunk freezes the turn. The chat twin of a PTY `write`. Resolves once
-   * the turn stream is wired (not when the turn completes).
-   */
-  sendPrompt(
-    sessionId: string,
-    prompt: string,
-    onReply: (chunk: ReplyChunk) => void,
-  ): Promise<void>;
-  /**
-   * Re-attaches a chat view to an **already-living** structured session without
-   * re-sending or re-spawning it (ARCHITECTURE §17.7, command
-   * `reattach_agent_chat`). Returns the retained conversation scrollback (the
-   * chunks already streamed) so the view repaints its prior turns; subsequent
-   * chunks then arrive over `onReply`. The chat twin of {@link reattach}.
-   *
-   * Rejects if no live structured session owns the id (the caller then opens
-   * fresh).
-   */
-  reattachChat(
-    sessionId: string,
-    onReply: (chunk: ReplyChunk) => void,
-  ): Promise<ReplyChunk[]>;
-  /**
-   * Shuts a live structured session down and tears its transport (channel +
-   * conversation scrollback) down (ARCHITECTURE §17.7, command
-   * `close_agent_session`). The chat twin of {@link TerminalGateway.closeTerminal};
-   * reserved for an explicit user action — navigation must never call this.
-   */
-  closeAgentSession(sessionId: string): Promise<void>;
 }
 
 /** Options for opening a terminal. */
@@ -257,14 +222,6 @@ export interface TerminalHandle {
    * leaf so the next open resumes instead of re-assigning.
    */
   readonly assignedConversationId?: string;
-  /**
-   * How the cell hosting this session should render (ARCHITECTURE §17.6).
-   * Present on handles returned by {@link AgentGateway.launchAgent}: `"chat"`
-   * routes the leaf to an `AgentChatView`, `"pty"` (the default) to a raw
-   * {@link TerminalView}. `undefined` on plain-terminal handles ⇒ treated as
-   * `"pty"`.
-   */
-  readonly cellKind?: import("@/domain").CellKind;
   /** Sends bytes (xterm keystrokes) to the PTY. */
   write(data: Uint8Array): Promise<void>;
   /** Resizes the PTY. */
@@ -529,6 +486,25 @@ export interface MemoryGateway {
   ): Promise<MemoryIndexEntry[]>;
 }
 
+/**
+ * Mediated agent input (lot F1, cadrage §4.2). All human input to an *agent*
+ * cell flows through this port instead of being written straight to the PTY:
+ * "Envoyer" enqueues a task in the agent's single FIFO (`submit`), "Interrompre"
+ * preempts the current turn (`interrupt`). The component talks to this gateway,
+ * never to `invoke()` directly.
+ *
+ * Note (forward/fallback, §4.2/§6): `submit` must never be blocked client-side
+ * when the agent is busy — the UI may *disable the button visually* but the
+ * enqueue path stays available; the backend FIFO is the single point that
+ * serialises. So callers may still call `submit` while busy.
+ */
+export interface InputGateway {
+  /** Envoyer = enqueue: appends `text` to the agent's input FIFO. */
+  submit(projectId: string, agentId: string, text: string): Promise<void>;
+  /** Interrompre = preempt: signals the current turn to stop (not an enqueue). */
+  interrupt(projectId: string, agentId: string): Promise<void>;
+}
+
 /**
  * AI profiles & first-run (L5). Drives the first-run wizard and profile
  * management: the pre-filled reference catalogue, detection of installed CLIs,
@@ -581,6 +557,7 @@ export interface EmbedderGateway {
 export interface Gateways {
   system: SystemGateway;
   agent: AgentGateway;
+  input: InputGateway;
   terminal: TerminalGateway;
   project: ProjectGateway;
   layout: LayoutGateway;