From d7cfbec796e5e24d436e396320c5b32a1ee2ccc3 Mon Sep 17 00:00:00 2001
From: Shuvam Kumar <145355204+shuvamk@users.noreply.github.com>
Date: Thu, 23 Jul 2026 19:26:09 +0530
Subject: [PATCH] fix(backlinks): keep truncateMiddle within maxLength (#134)

---
 .../backlinks/backlinksPageUtils.test.ts      | 33 +++++++++++++++++++
 .../features/backlinks/backlinksPageUtils.ts  | 11 +++++--
 2 files changed, 42 insertions(+), 2 deletions(-)
 create mode 100644 src/client/features/backlinks/backlinksPageUtils.test.ts

diff --git a/src/client/features/backlinks/backlinksPageUtils.test.ts b/src/client/features/backlinks/backlinksPageUtils.test.ts
new file mode 100644
index 0000000..74cc855
--- /dev/null
+++ b/src/client/features/backlinks/backlinksPageUtils.test.ts
@@ -0,0 +1,33 @@
+import { describe, expect, it } from "vitest";
+import { truncateMiddle } from "./backlinksPageUtils";
+
+describe("truncateMiddle", () => {
+  it("returns the value unchanged when it already fits", () => {
+    expect(truncateMiddle("short", 10)).toBe("short");
+    expect(truncateMiddle("exactly-ten", "exactly-ten".length)).toBe(
+      "exactly-ten",
+    );
+  });
+
+  it("never returns a string longer than maxLength", () => {
+    const value = "/very/long/path/segment/that/keeps/going/here";
+    for (let maxLength = 0; maxLength <= value.length; maxLength++) {
+      expect(truncateMiddle(value, maxLength).length).toBeLessThanOrEqual(
+        maxLength,
+      );
+    }
+  });
+
+  it("keeps head and tail around a middle ellipsis", () => {
+    expect(truncateMiddle("abcdefghijklmno", 10)).toBe("abc...mno");
+    expect(truncateMiddle("/very/long/path/segment/here", 12)).toBe(
+      "/ver...here",
+    );
+  });
+
+  it("head-truncates when there is no room for both sides", () => {
+    expect(truncateMiddle("abcdefgh", 4)).toBe("a...");
+    expect(truncateMiddle("abcdefgh", 3)).toBe("abc");
+    expect(truncateMiddle("abcdefgh", 2)).toBe("ab");
+  });
+});
diff --git a/src/client/features/backlinks/backlinksPageUtils.ts b/src/client/features/backlinks/backlinksPageUtils.ts
index 94a3338..78b7b2b 100644
--- a/src/client/features/backlinks/backlinksPageUtils.ts
+++ b/src/client/features/backlinks/backlinksPageUtils.ts
@@ -114,8 +114,15 @@ export function extractUrlPath(url: string) {
   }
 }
 
+const ELLIPSIS = "...";
+
 export function truncateMiddle(value: string, maxLength: number) {
   if (value.length <= maxLength) return value;
-  const sideLength = Math.floor((maxLength - 1) / 2);
-  return `${value.slice(0, sideLength)}...${value.slice(-sideLength)}`;
+  if (maxLength <= ELLIPSIS.length)
+    return value.slice(0, Math.max(maxLength, 0));
+  const sideLength = Math.floor((maxLength - ELLIPSIS.length) / 2);
+  if (sideLength <= 0) {
+    return `${value.slice(0, maxLength - ELLIPSIS.length)}${ELLIPSIS}`;
+  }
+  return `${value.slice(0, sideLength)}${ELLIPSIS}${value.slice(-sideLength)}`;
 }