diff --git a/src/auto-reply/reply/agent-runner-execution.ts b/src/auto-reply/reply/agent-runner-execution.ts
index 4141c8c9bc8..687e4ecf05a 100644
--- a/src/auto-reply/reply/agent-runner-execution.ts
+++ b/src/auto-reply/reply/agent-runner-execution.ts
@@ -418,10 +418,24 @@ export async function runAgentTurnWithFallback(params: {
                     if (phase === "start") {
                       if (params.opts?.onCompactionStart) {
                         await params.opts.onCompactionStart();
-                      } else {
+                      } else if (params.blockStreamingEnabled) {
                         // Route through the shared block reply handler so
                         // reply-to threading matches other in-run notices.
                         await blockReplyHandler?.({ text: "🧹 Compacting context..." });
+                      } else if (params.opts?.onBlockReply) {
+                        // blockReplyHandler is a no-op when streaming is disabled.
+                        // Fall back to direct delivery so non-streaming runs also
+                        // receive the compaction start notice.
+                        const currentMessageId =
+                          params.sessionCtx.MessageSidFull ?? params.sessionCtx.MessageSid;
+                        const noticePayload = params.applyReplyToMode({
+                          text: "🧹 Compacting context...",
+                          replyToId: currentMessageId,
+                          replyToCurrent: true,
+                        });
+                        await params.opts.onBlockReply(noticePayload);
+                      } else {
+                        await params.opts?.onBlockReply?.({ text: "🧹 Compacting context..." });
                       }
                     }
                     const completed = evt.data?.completed === true;
diff --git a/src/auto-reply/reply/agent-runner.ts b/src/auto-reply/reply/agent-runner.ts
index 7bec12d1c8a..73473949db1 100644
--- a/src/auto-reply/reply/agent-runner.ts
+++ b/src/auto-reply/reply/agent-runner.ts
@@ -423,7 +423,7 @@ export async function runReplyAgent(params: {
     // stopped, so the enqueue does not set didStream() = true and cause
     // buildReplyPayloads to discard the real assistant reply.  We still apply a
     // timeout so the notice cannot stall the run indefinitely.
-    if (autoCompactionCompleted && opts?.onBlockReply) {
+    if (autoCompactionCompleted && blockStreamingEnabled && opts?.onBlockReply) {
       const verboseEnabled = resolvedVerboseLevel !== "off";
       const completionText = verboseEnabled
         ? `🧹 Auto-compaction complete.`