From 14c63ca42a1133dde51c050e301bd6ecb6e2c86f Mon Sep 17 00:00:00 2001
From: Shakker <shakkerdroid@gmail.com>
Date: Fri, 27 Mar 2026 10:29:32 +0000
Subject: [PATCH] fix(tui): prune chat log system messages atomically

---
 src/tui/components/chat-log.test.ts | 16 ++++++++++++++++
 src/tui/components/chat-log.ts      | 10 ++++++++--
 2 files changed, 24 insertions(+), 2 deletions(-)

diff --git a/src/tui/components/chat-log.test.ts b/src/tui/components/chat-log.test.ts
index 700a2abb9d2..a57de225f52 100644
--- a/src/tui/components/chat-log.test.ts
+++ b/src/tui/components/chat-log.test.ts
@@ -53,6 +53,22 @@ describe("ChatLog", () => {
     expect(chatLog.children.length).toBe(20);
   });
 
+  it("prunes system messages atomically when a non-system entry overflows the log", () => {
+    const chatLog = new ChatLog(20);
+    for (let i = 1; i <= 20; i++) {
+      chatLog.addSystem(`system-${i}`);
+    }
+
+    chatLog.addUser("hello");
+
+    const rendered = chatLog.render(120).join("\n");
+    expect(rendered).not.toMatch(/\bsystem-1\b/);
+    expect(rendered).toMatch(/\bsystem-2\b/);
+    expect(rendered).toMatch(/\bsystem-20\b/);
+    expect(rendered).toContain("hello");
+    expect(chatLog.children.length).toBe(20);
+  });
+
   it("renders BTW inline and removes it when dismissed", () => {
     const chatLog = new ChatLog(40);
 
diff --git a/src/tui/components/chat-log.ts b/src/tui/components/chat-log.ts
index c46e6065b9b..07dd91d21c0 100644
--- a/src/tui/components/chat-log.ts
+++ b/src/tui/components/chat-log.ts
@@ -57,9 +57,15 @@ export class ChatLog extends Container {
     this.btwMessage = null;
   }
 
+  private createSystemMessage(text: string): Container {
+    const entry = new Container();
+    entry.addChild(new Spacer(1));
+    entry.addChild(new Text(theme.system(text), 1, 0));
+    return entry;
+  }
+
   addSystem(text: string) {
-    this.append(new Spacer(1));
-    this.append(new Text(theme.system(text), 1, 0));
+    this.append(this.createSystemMessage(text));
   }
 
   addUser(text: string) {