fix(rectification): pass birthDate into the choice-path gate

The post-choice decision used a looser plan than the followup builder.
Load compute once in persistApplied and feed the same birthDate to both.

Co-authored-by: Cursor <cursoragent@cursor.com>

frontend/src/lib/rectification-agentic/v9/answer-choice.ts

@@ -252,6 +252,7 @@ async function persistNextInterviewAfterChoice(input: {
   dossier: Parameters<typeof decideAfterInferenceChange>[0]["dossier"];
   decisionState: InferenceState | null;
   nextAction: ReturnType<typeof publicNextAction>;
+  birthDate?: string | null;
 }): Promise<{ hostNarration: string | null; choiceReady: boolean }> {
   const latest = input.dossier.latestResult
     ? {
@@ -264,13 +265,7 @@ async function persistNextInterviewAfterChoice(input: {
     : {
       decisionReceipt: input.decisionState ? { inference_state: input.decisionState } : null,
     };
-  let birthDate: string | null = null;
-  try {
-    const compute = await loadV9CaseCompute(input.accounting, input.userId, input.caseId);
-    birthDate = String(compute.baselineBirthSnapshot.birth_date ?? "") || null;
-  } catch {
-    // Ranking stays fail-open when compute is unavailable.
-  }
+  const birthDate = input.birthDate ?? null;
   const catalog = rectificationFollowupCatalog(latest, input.dossier.evidence);
   const sessionOutcome = typeof input.nextAction.session_outcome === "string"
     ? input.nextAction.session_outcome as SessionOutcomeKind
@@ -404,10 +399,18 @@ async function persistApplied(
     inference: input.inference,
   });
 
+  let birthDate: string | null = null;
+  try {
+    const compute = await loadV9CaseCompute(accounting, command.userId, command.caseId);
+    birthDate = String(compute.baselineBirthSnapshot.birth_date ?? "") || null;
+  } catch {
+    // Ranking stays fail-open when compute is unavailable.
+  }
   const nextAction = publicNextAction(decideAfterInferenceChange({
     dossier: input.dossier,
     state: input.decisionState ?? null,
     userStopped: input.userStopped === true,
+    birthDate,
   }));
 
   let narrationPersisted = false;
@@ -422,6 +425,7 @@ async function persistApplied(
       dossier: input.dossier,
       decisionState: input.decisionState ?? null,
       nextAction,
+      birthDate,
     });
     nextChoiceReady = nextInterview.choiceReady;
     if (nextInterview.hostNarration) {