收紧策划 continuation 游标防止旧 delivery 越权

新增 planning session latestDelegationId 直接后继校验，阻止旧 delivery 另起分支

保留用户修订周期内质量返工的 user_revision 语义并更新提交门注释

补充 continuation 边界回归与 Fast GDD 技术决策文档

apps/ai-game-creator-shell/src-tauri/src/agent/runtime_protocol/planning_coordinator.rs

@@ -25,6 +25,25 @@ fn plan_coordinator_error(kind: &str, detail: impl AsRef<str>) -> String {
     format!("{kind}: {}", detail.as_ref())
 }
 
+fn validate_plan_continuation_parent<'a>(
+    latest_delegation_id: &str,
+    delivery: &'a StaticDelegateDeliveryRecord,
+) -> Result<&'a str, String> {
+    let original_id = delivery.repair_of_delegation_id.as_deref().ok_or_else(|| {
+        plan_coordinator_error(
+            "PLAN_ACTIVE_RUN_EXISTS",
+            "已有 planning session 时不能创建第二条根 delegation",
+        )
+    })?;
+    if latest_delegation_id != original_id {
+        return Err(plan_coordinator_error(
+            "PLAN_NEEDS_RECONCILIATION",
+            "planning continuation 必须直接继承当前 session 的 latest delegation",
+        ));
+    }
+    Ok(original_id)
+}
+
 fn plan_session_successor_base(previous: &PlanSessionV1) -> Result<PlanSessionV1, String> {
     let mut next = previous.clone();
     next.session_revision = previous.session_revision.checked_add(1).ok_or_else(|| {
@@ -230,6 +249,45 @@ mod option_label_delimiter_tests {
     }
 }
 
+#[cfg(test)]
+mod planning_continuation_parent_tests {
+    use super::*;
+
+    fn delivery(repair_of_delegation_id: Option<&str>) -> StaticDelegateDeliveryRecord {
+        new_static_delegate_delivery_with_contract(
+            GAME_CREATOR_PROJECT_SUPERVISOR_AGENT_ID,
+            "supervisor-session",
+            "supervisor-run",
+            "delegate-action",
+            "current-delivery",
+            GAME_CREATOR_PROJECT_PLANNING_AGENT_ID,
+            "planning-session",
+            "planning-run",
+            &[],
+            &[],
+            repair_of_delegation_id,
+        )
+    }
+
+    #[test]
+    fn continuation_must_extend_the_session_cursor() {
+        let continuation = delivery(Some("older-delivery"));
+        let error = validate_plan_continuation_parent("current-delivery", &continuation)
+            .expect_err("older delivery must not become the current planning branch");
+        assert!(error.contains("latest delegation"));
+    }
+
+    #[test]
+    fn continuation_accepts_the_current_session_cursor() {
+        let continuation = delivery(Some("current-delivery"));
+        assert_eq!(
+            validate_plan_continuation_parent("current-delivery", &continuation)
+                .expect("current delivery is a valid continuation"),
+            "current-delivery"
+        );
+    }
+}
+
 fn plan_option_label_matches_answer(label: &str, normalized_answer: &str) -> bool {
     label == normalized_answer
 }
@@ -584,12 +642,13 @@ pub(crate) fn ensure_plan_session_for_planning_child_task_at_locked(
     {
         return Ok(true);
     }
-    let original_id = delivery.repair_of_delegation_id.as_deref().ok_or_else(|| {
-        plan_coordinator_error(
-            "PLAN_ACTIVE_RUN_EXISTS",
-            "已有 planning session 时不能创建第二条根 delegation",
-        )
-    })?;
+    // `latest_delegation_id` is the planning session's single continuation
+    // cursor.  A new child must extend that cursor directly; otherwise a
+    // Supervisor can select an older claimed delivery and make an unrelated
+    // branch look like the current session.  Keep this check here, after the
+    // exact-task replay fast path above, so replaying an already projected
+    // child remains idempotent.
+    let original_id = validate_plan_continuation_parent(&previous.latest_delegation_id, &delivery)?;
     let deliveries = list_static_delegate_deliveries_at(root)?;
     if static_delegate_lineage_contains_unknown_contract_status(
         &deliveries,

apps/ai-game-creator-shell/src-tauri/src/agent/runtime_protocol/planning_submit.rs

@@ -1189,9 +1189,10 @@ fn validate_current_session_cas(
     Ok(())
 }
 
-/// `user_revision` 只证明审批意见，不证明澄清。首次 collecting、澄清续跑和提交前
-/// 质量返工的 session 都没有 revise/reject `lastDecisionRef`；合法续跑会把该引用
-/// 带到新的 collecting successor 上。replay 不走这里。
+/// `user_revision` 只证明审批意见，不证明澄清。首次 collecting、澄清续跑和没有待处理
+/// 用户修订的普通质量返工 session 都没有 revise/reject `lastDecisionRef`；用户修订周期
+/// 内的 continuation（包括其质量返工）会把该引用带到新的 collecting successor 上。
+/// continuation 的直接父边由 planning coordinator 校验，replay 不走这里。
 fn validate_user_revision_requires_approval_decision(
     session: &PlanSessionV1,
     input: &PlanSubmitGddInputV1,