fix(codex): preserve project root on structured resume

Recalcule la policy structured Codex lors des reprises custom/headless afin que le project root et le managed tmp soient transmis en writable_roots. Fail-closed si une session Codex structured est lancée sans policy explicite.

crates/backend/src/lib.rs

@@ -1100,6 +1100,28 @@ fn self_restart_launch_input(
     }
 }
 
+fn automatic_resume_launch_input(
+    context: ResumeContext,
+    agent_id: AgentId,
+    node_id: domain::NodeId,
+    conversation_id: Option<String>,
+    mcp_runtime: Option<McpRuntime>,
+) -> LaunchAgentInput {
+    LaunchAgentInput {
+        project: context.project,
+        agent_id,
+        rows: context.rows,
+        cols: context.cols,
+        node_id: Some(node_id),
+        conversation_id,
+        mcp_runtime,
+        allow_structured_alongside_pty: false,
+        require_structured: context.require_structured,
+        fresh_start: false,
+        managed_temp_exposure: application::ManagedTempExposureRequest::default(),
+    }
+}
+
 #[cfg(test)]
 mod self_restart_contract_tests {
     use super::*;
@@ -1137,6 +1159,42 @@ mod self_restart_contract_tests {
         assert!(!input.fresh_start);
     }
 
+    #[test]
+    fn automatic_resume_preserves_custom_chat_structured_routing() {
+        let project = Project::new(
+            ProjectId::from_uuid(Uuid::from_u128(306)),
+            "resume",
+            domain::project::ProjectPath::new("/external/project-root").unwrap(),
+            domain::remote::RemoteRef::local(),
+            0,
+        )
+        .unwrap();
+        let agent = AgentId::from_uuid(Uuid::from_u128(1));
+        let node = domain::NodeId::from_uuid(Uuid::from_u128(2));
+        let input = automatic_resume_launch_input(
+            ResumeContext {
+                project,
+                rows: 24,
+                cols: 80,
+                node_id: Some(node),
+                conversation_id: Some("old-conversation".to_owned()),
+                require_structured: true,
+            },
+            agent,
+            node,
+            Some("current-conversation".to_owned()),
+            None,
+        );
+
+        assert!(input.require_structured);
+        assert_eq!(input.node_id, Some(node));
+        assert_eq!(
+            input.conversation_id.as_deref(),
+            Some("current-conversation")
+        );
+        assert!(!input.fresh_start);
+    }
+
     #[tokio::test]
     async fn human_turn_ignores_old_terminal_and_accepts_replacement() {
         let mailbox = Arc::new(InMemoryMailbox::new());
@@ -1682,19 +1740,13 @@ impl AgentResumer for AppAgentResumer {
 
         let project_id = ctx.project.id;
         self.launch_agent
-            .execute(LaunchAgentInput {
-                project: ctx.project,
+            .execute(automatic_resume_launch_input(
+                ctx,
                 agent_id,
-                rows: ctx.rows,
-                cols: ctx.cols,
-                node_id: Some(node_id),
+                node_id,
                 conversation_id,
                 mcp_runtime,
-                allow_structured_alongside_pty: false,
-                require_structured: false,
-                fresh_start: false,
-                managed_temp_exposure: application::ManagedTempExposureRequest::default(),
-            })
+            ))
             .await?;
 
         // Premier tour de reprise par le **portail d'entrée** (pas de write brut, §20) :