chore(wip): checkpoint P8/C avant chantier Codex inter-agents

Sauvegarde de l'arbre de travail en cours (persistance P8, conversations
C-series, write-portal frontend, médiation d'entrée) avant d'attaquer le
support de la délégation inter-agents pour les profils Codex.

Le round-trip inter-agent question/réponse est couvert sans tokens par
les tests loopback existants (state::mcp_e2e_loopback_tests).

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

frontend/src/ports/index.ts

@@ -242,6 +242,33 @@ export interface TerminalHandle {
   close(): Promise<void>;
 }
 
+/**
+ * The write-portal contract an agent-cell terminal talks to (ARCHITECTURE §20).
+ * The portal owns the *human line* counter, the suspension flag (raised while it
+ * injects a delegation) and — once the view has a live PTY — the handle it
+ * writes through. The terminal view is the only effective PTY writer
+ * (single-writer invariant): it relays human keystrokes and the portal injects
+ * via the same handle, never a second physical writer.
+ */
+export interface WritePortal {
+  /**
+   * Reports a raw human keystroke chunk (`term.onData`) so the portal can keep
+   * its line counter. Called for **every** keystroke in agent mode, including
+   * while suspended (the portal decides what to count).
+   */
+  onHumanData(data: string): void;
+  /**
+   * Whether the keystroke relay to the PTY is currently suspended (the portal
+   * is injecting a delegation). When `true`, the view drops keystrokes so they
+   * do not race the injected text.
+   */
+  isSuspended(): boolean;
+  /** Binds the live PTY handle so the portal can inject through it. */
+  bindHandle(handle: TerminalHandle): void;
+  /** Drops the handle reference (view torn down). */
+  unbindHandle(): void;
+}
+
 /**
  * Terminals (L3): open a PTY with a per-session output stream, then write/
  * resize/close it through the returned {@link TerminalHandle}.
@@ -487,22 +514,32 @@ export interface MemoryGateway {
 }
 
 /**
- * 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.
+ * Agent input control (ARCHITECTURE §20). The mediated-input strip is gone: the
+ * agent cell is a **native terminal** and human keystrokes (Enter included) go
+ * straight to the PTY. This port only carries the two out-of-band controls:
  *
- * 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.
+ *  - **Interrompre** → `interrupt` (preempt the current turn — a control byte,
+ *    not an enqueue).
+ *  - **Ack** → `delegationDelivered`: the cell's write-portal confirms it has
+ *    effectively written a delegation's text into the native PTY (closes the
+ *    "the turn was delivered" loop for observability; the `ask` wake-up still
+ *    rides on `idea_reply`).
+ *
+ * The component talks to this gateway via DI, never to `invoke()` directly.
  */
 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>;
+  /**
+   * Ack: the cell's write-portal has written the delegation `ticket` into the
+   * agent's native PTY (ARCHITECTURE §20.3). Best-effort; never changes the
+   * ticket correlation.
+   */
+  delegationDelivered(
+    projectId: string,
+    agentId: string,
+    ticket: string,
+  ): Promise<void>;
 }
 
 /**