From 205ab8d4bd7a9347bba5cecd5dd9de6c87a5e327 Mon Sep 17 00:00:00 2001
From: Anson_H <153708448+yyzquwu@users.noreply.github.com>
Date: Sat, 13 Jun 2026 06:54:53 -0700
Subject: [PATCH] perf(terminal): reuse ANSI truncation scanner

Reuse one module-level ANSI/OSC scanner during visible-width truncation and reset scanner state between calls. Keeps styled, plain, and OSC-8 truncation behavior covered by regression tests.
---
 packages/terminal-core/src/ansi.test.ts | 9 +++++++++
 packages/terminal-core/src/ansi.ts      | 5 +++--
 2 files changed, 12 insertions(+), 2 deletions(-)

diff --git a/packages/terminal-core/src/ansi.test.ts b/packages/terminal-core/src/ansi.test.ts
index 2b5f86a03b3..f43061776a7 100644
--- a/packages/terminal-core/src/ansi.test.ts
+++ b/packages/terminal-core/src/ansi.test.ts
@@ -60,4 +60,13 @@ describe("terminal ansi helpers", () => {
     expect(truncateToVisibleWidth("表文", 1)).toBe("");
     expect(visibleWidth(truncateToVisibleWidth("表文", 1))).toBe(0);
   });
+
+  it("reuses the ANSI scanner across truncation calls", () => {
+    expect(truncateToVisibleWidth("\u001B[31mabc\u001B[0m", 2)).toBe("\u001B[31mab\u001B[0m");
+    expect(truncateToVisibleWidth("plain", 3)).toBe("pla");
+    expect(
+      truncateToVisibleWidth("\u001B]8;;https://openclaw.ai\u001B\\link\u001B]8;;\u001B\\", 2),
+    ).toBe("\u001B]8;;https://openclaw.ai\u001B\\li\u001B]8;;\u001B\\");
+    expect(truncateToVisibleWidth("\u001B[32mxy\u001B[0m", 1)).toBe("\u001B[32mx\u001B[0m");
+  });
 });
diff --git a/packages/terminal-core/src/ansi.ts b/packages/terminal-core/src/ansi.ts
index bb5c164d87c..0739344df7a 100644
--- a/packages/terminal-core/src/ansi.ts
+++ b/packages/terminal-core/src/ansi.ts
@@ -6,6 +6,7 @@ const ANSI_OSC_PATTERN = "\\x1b\\][^\\x07\\x1b]*(?:\\x1b\\\\|\\x07)";
 
 const ANSI_CSI_REGEX = new RegExp(ANSI_CSI_PATTERN, "g");
 const ANSI_OSC_REGEX = new RegExp(ANSI_OSC_PATTERN, "g");
+const ANSI_SEQUENCE_REGEX = new RegExp(`${ANSI_OSC_PATTERN}|${ANSI_CSI_PATTERN}`, "g");
 const graphemeSegmenter =
   typeof Intl !== "undefined" && "Segmenter" in Intl
     ? new Intl.Segmenter(undefined, { granularity: "grapheme" })
@@ -134,7 +135,7 @@ export function truncateToVisibleWidth(input: string, maxWidth: number): string
   if (visibleWidth(input) <= maxWidth) {
     return input;
   }
-  const ansi = new RegExp(`${ANSI_OSC_PATTERN}|${ANSI_CSI_PATTERN}`, "g");
+  ANSI_SEQUENCE_REGEX.lastIndex = 0;
   let out = "";
   let used = 0;
   let pos = 0;
@@ -157,7 +158,7 @@ export function truncateToVisibleWidth(input: string, maxWidth: number): string
     }
   };
   let match: RegExpExecArray | null;
-  while ((match = ansi.exec(input)) !== null) {
+  while ((match = ANSI_SEQUENCE_REGEX.exec(input)) !== null) {
     appendVisible(input.slice(pos, match.index));
     out += match[0];
     pos = match.index + match[0].length;