fix: cancel session and binary drag-drop

src/backend/listener.ts

@@ -95,7 +95,9 @@ export class EventStreamListener {
       const isTimeout = resp.error.message === "timeout";
       if (!isTimeout || attempt === MAX_ATTEMPTS) {
         if (isTimeout) {
-          warn(`subscribe: all ${MAX_ATTEMPTS} attempts timed out (backend unresponsive for ~${Math.round((MAX_ATTEMPTS * 5000 + 500) / 1000)}s)`);
+          warn(
+            `subscribe: all ${MAX_ATTEMPTS} attempts timed out (backend unresponsive for ~${Math.round((MAX_ATTEMPTS * 5000 + 500) / 1000)}s)`,
+          );
         }
         throw new Error(formatSubscribeError(resp));
       }
@@ -126,6 +128,15 @@ export class EventStreamListener {
     }
   }
 
+  /**
+   * True if events are queued waiting for a poll (non-destructive). Lets the
+   * turn loop check liveness without consuming an event — used by the stall
+   * reconciliation to confirm a turn is still alive before ending it.
+   */
+  hasQueuedEvents(): boolean {
+    return this.queue.length > 0;
+  }
+
   /**
    * Wait for the next event, resolving once one arrives or `timeoutMs` elapses
    * (resolves null on timeout). Events arriving with no active waiter are

src/config/auto-compact.ts

@@ -40,35 +40,36 @@ export async function maybeAutoCompact(
   const threshold = autoCompactThreshold();
   if (threshold <= 0) return; // disabled
 
-  // Read current context usage via session/read.
-  let used = 0;
+  const msgId = randomUUID();
   try {
-    const backend = server.ensureBackend();
-    const resp = await backend.request(
-      server.nextId(),
-      "session/read",
-      { sessionId: zcodeSid },
-      5000,
-    );
-    if (resp.error) return;
-    const result = (resp.result ?? {}) as { projection?: { contextUsed?: number } };
-    used = result.projection?.contextUsed ?? 0;
-  } catch (e) {
-    warn(`auto-compact: session/read failed (${e instanceof Error ? e.message : String(e)})`);
-    return;
-  }
+    // Read current context usage via session/read.
+    let used = 0;
+    try {
+      const backend = server.ensureBackend();
+      const resp = await backend.request(
+        server.nextId(),
+        "session/read",
+        { sessionId: zcodeSid },
+        5000,
+      );
+      if (resp.error) return;
+      const result = (resp.result ?? {}) as { projection?: { contextUsed?: number } };
+      used = result.projection?.contextUsed ?? 0;
+    } catch (e) {
+      warn(`auto-compact: session/read failed (${e instanceof Error ? e.message : String(e)})`);
+      return;
+    }
 
-  if (used < threshold) return;
+    if (used < threshold) return;
+
+    log(`auto-compact: contextUsed=${used} >= threshold=${threshold}, compacting…`);
+    await sendTextChunk(
+      cx,
+      acpSid,
+      `🔄 auto-compact: context usage ${used.toLocaleString()} ≥ threshold ${threshold.toLocaleString()}, compressing…`,
+      msgId,
+    );
 
-  log(`auto-compact: contextUsed=${used} >= threshold=${threshold}, compacting…`);
-  const msgId = randomUUID();
-  await sendTextChunk(
-    cx,
-    acpSid,
-    `🔄 auto-compact: context usage ${used.toLocaleString()} ≥ threshold ${threshold.toLocaleString()}, compressing…`,
-    msgId,
-  );
-  try {
     // compact() handles: session/compact → waitForTurnIdle → emitInitialUsage.
     const result = (await compact(server, { sessionId: acpSid }, cx)) as {
       __lockTimeout?: boolean;

src/handlers/dispatch.ts

@@ -312,7 +312,11 @@ async function dispatchUsageDelta(
   // config.json limit.context so the editor can render the context bar.
   let size = ev.size;
   if (!size) {
-    const { providerId, modelId } = parseModelValue(await currentModelCached(server, acpSid));
+    // Resolve to the real backend session id — `acpSid` may be a lazy
+    // session/new placeholder that the backend rejects with "Session is not
+    // active", wasting a 5s request timeout on every usage_update.
+    const zcodeSid = server.resolveSid(acpSid) ?? acpSid;
+    const { providerId, modelId } = parseModelValue(await currentModelCached(server, zcodeSid));
     size = modelContextWindow(providerId, modelId);
   }
   await sendSessionUpdate(cx, acpSid, {