perf(heartbeat): schedule retry promotion from durable deadlines

Co-Authored-By: Paperclip <noreply@paperclip.ing>

server/src/modules/run-dispatch/adapters/postgres.ts

@@ -511,6 +511,14 @@ export function createPostgresRunDispatchAdapter(
     return decideScheduledRetryGate(factsResult.facts, input.now);
   }
 
+  async function nextScheduledRetryAt(input: { cutoff: Date | null }): Promise<number | null> {
+    const [row] = await db.select({ at: heartbeatRuns.scheduledRetryAt }).from(heartbeatRuns)
+      .where(and(eq(heartbeatRuns.status, "scheduled_retry"),
+        input.cutoff ? gte(heartbeatRuns.createdAt, input.cutoff) : undefined))
+      .orderBy(asc(heartbeatRuns.scheduledRetryAt)).limit(1);
+    return row?.at?.getTime() ?? null;
+  }
+
   async function listDueRetries(input: ListDueRetriesInput): Promise<DueRetryRun[]> {
     const rows = await db
       .select()
@@ -1414,6 +1422,7 @@ export function createPostgresRunDispatchAdapter(
 
   return {
     evaluateScheduledRetryGate,
+    nextScheduledRetryAt,
     listDueRetries,
     cancelStaleQueuedRun,
     dispatchResolvedInteractionIfCurrent,

server/src/modules/run-dispatch/application/ports.ts

@@ -24,6 +24,7 @@ export type EvaluateScheduledRetryGateInput = {
 
 /** Read-only scheduled-retry operations exposed to application use cases. */
 export interface ScheduledRetryReader {
+  nextScheduledRetryAt(input: { cutoff: Date | null }): Promise<number | null>;
   evaluateScheduledRetryGate(input: EvaluateScheduledRetryGateInput): Promise<GateDecision>;
   listDueRetries(input: ListDueRetriesInput): Promise<DueRetryRun[]>;
 }

server/src/modules/run-dispatch/application/use-cases.test.ts

@@ -12,6 +12,7 @@ function fakeReader(dueRuns: DueRetryRun[] = []): ScheduledRetryReader & { evalu
   const evaluateCalls: unknown[] = [];
   return {
     evaluateCalls,
+    async nextScheduledRetryAt() { return null; },
     async evaluateScheduledRetryGate(input) {
       evaluateCalls.push(input);
       return { allowed: true };

server/src/modules/run-dispatch/index.ts

@@ -67,6 +67,7 @@ export function createRunDispatch(db: Db, deps: RunDispatchDeps = {}) {
   });
 
   return {
+    nextScheduledRetryAt: (input: { cutoff: Date | null }) => adapter.nextScheduledRetryAt(input),
     evaluateScheduledRetryGate: createEvaluateScheduledRetryGate({ reader: adapter }),
     promoteScheduledRetry,
     promoteDueScheduledRetries: createPromoteDueScheduledRetries({