fix(windows): the step ticker no longer stops at a session's twentieth step

windows/src/core/state.ts

@@ -13,6 +13,11 @@ export interface AgentTask {
   state: BotStateName;
   stepIndex: number;
   steps: string[];
+  /**
+   * Position of the newest step in the whole session. `steps` is capped, so
+   * `stepIndex` stops moving once it is full; this keeps counting.
+   */
+  stepSeq?: number;
   source: AgentSource;
   isIntegration: boolean;
   emote?: BotEmoteName | null;
@@ -186,9 +191,11 @@ class AppState {
   appendStep(id: string, step: string) {
     const t = this.tasks.find((x) => x.id === id);
     if (!t) return;
+    const newest = t.stepSeq ?? t.steps.length - 1;
     t.steps.push(step);
     if (t.steps.length > 20) t.steps.shift();
     t.stepIndex = t.steps.length - 1;
+    t.stepSeq = newest + 1;
     this.notify();
   }
 

windows/src/island/hooks.ts

@@ -132,6 +132,7 @@ function clearSession() {
   if (!t) return;
   t.steps = [];
   t.stepIndex = 0;
+  delete t.stepSeq;
   t.name = "VS Code";
   t.pillBadge = null;
 }

windows/src/views/ticker.ts

@@ -96,31 +96,27 @@ export class Ticker {
   }
 
   sync(task: AgentTask | null) {
-    const steps = task && task.steps.length > 0 ? task.steps : ["…"];
-    const idx = task ? Math.min(task.stepIndex, steps.length - 1) : -1;
-
-    // First render: drop straight into place, no animation.
-    if (this.displayIndex < 0) {
-      this.displayIndex = idx;
-      setText(this.a, idx > 0 ? steps[idx - 1] : "…");
-      setText(this.b, steps[Math.max(idx, 0)]);
-      this.rest();
-      return;
-    }
-
-    // The session restarted (steps were cleared): re-seed rather than scroll.
-    if (idx < this.displayIndex) {
+    const steps = task?.steps ?? [];
+    // Where the newest step sits in the whole session, not in `steps`: that
+    // list is capped at 20, and counting inside it made the ticker stop for
+    // good at the twentieth step of a session.
+    const newest = steps.length === 0 ? -1 : (task?.stepSeq ?? steps.length - 1);
+
+    // First render, or the session restarted (steps were cleared): drop
+    // straight into place rather than scroll.
+    if (this.displayIndex < 0 || newest < this.displayIndex) {
       this.queue = [];
       this.startMs = null;
-      this.displayIndex = idx;
-      setText(this.a, idx > 0 ? steps[idx - 1] : "…");
-      setText(this.b, steps[Math.max(idx, 0)]);
+      this.displayIndex = newest;
+      setText(this.a, steps.at(-2) ?? "…");
+      setText(this.b, steps.at(-1) ?? "…");
       this.rest();
       return;
     }
 
-    for (let i = this.displayIndex + 1; i <= idx; i++) this.queue.push(steps[i]);
-    this.displayIndex = idx;
+    const fresh = Math.min(newest - this.displayIndex, steps.length);
+    if (fresh > 0) this.queue.push(...steps.slice(-fresh));
+    this.displayIndex = newest;
     if (this.queue.length > MAX_QUEUE) {
       this.queue = this.queue.slice(-MAX_QUEUE);
     }