Fix app stream/timeline ordering desync and init lifecycle race (#73)

* fix(app): enforce canonical stream sequencing and init resolution * refactor: extract timeline and stream reducers to pure functions
2026-02-23 19:30:48 +07:00
parent 9b6f5e028c
commit a134132418
12 changed files with 1732 additions and 109 deletions
@@ -0,0 +1,62 @@
+type TimelineDirection = "tail" | "before" | "after";
+type InitRequestDirection = "tail" | "after";
+
+type TimelineCursor = {
+  seq: number;
+} | null;
+
+export function deriveBootstrapTailTimelinePolicy({
+  direction,
+  reset,
+  epoch,
+  endCursor,
+  isInitializing,
+  hasActiveInitDeferred,
+}: {
+  direction: TimelineDirection;
+  reset: boolean;
+  epoch: string;
+  endCursor: TimelineCursor;
+  isInitializing: boolean;
+  hasActiveInitDeferred: boolean;
+}): {
+  replace: boolean;
+  catchUpCursor: { epoch: string; endSeq: number } | null;
+} {
+  if (reset) {
+    return { replace: true, catchUpCursor: null };
+  }
+
+  const isBootstrapTailInit =
+    direction === "tail" && isInitializing && hasActiveInitDeferred;
+  if (!isBootstrapTailInit) {
+    return { replace: false, catchUpCursor: null };
+  }
+
+  return {
+    replace: true,
+    catchUpCursor: endCursor ? { epoch, endSeq: endCursor.seq } : null,
+  };
+}
+
+export function shouldResolveTimelineInit({
+  hasActiveInitDeferred,
+  isInitializing,
+  initRequestDirection,
+  responseDirection,
+  reset,
+}: {
+  hasActiveInitDeferred: boolean;
+  isInitializing: boolean;
+  initRequestDirection: InitRequestDirection;
+  responseDirection: TimelineDirection;
+  reset: boolean;
+}): boolean {
+  if (!hasActiveInitDeferred || !isInitializing) {
+    return false;
+  }
+  if (reset) {
+    return true;
+  }
+  return responseDirection === initRequestDirection;
+}