fix: repair unclosed managed blocks

CHANGELOG.md

@@ -3,6 +3,13 @@
 All notable changes to this project are documented here, following
 [Keep a Changelog](https://keepachangelog.com/) and semantic versioning.
 
+## [0.1.4] - 2026-09-07
+
+### Fixed
+
+- Repair an unclosed managed ignore block in place instead of appending a
+  duplicate block on every run.
+
 ## [0.1.3] - 2026-09-06
 
 ### Fixed

package.json

@@ -1,6 +1,6 @@
 {
   "name": "ctxtrim",
-  "version": "0.1.3",
+  "version": "0.1.4",
   "description": "Trim what bloats your AI coding context. Scan a repo, find the high-cost/low-value files ballooning your Claude Code / Cursor / Codex context, and write ignore files to cut token cost. Zero dependencies.",
   "type": "module",
   "bin": {

src/ignore.js

@@ -21,9 +21,15 @@ export function block(patterns) {
 /** Insert or replace the managed block in existing content (keeps the user's own lines). */
 export function merge(existing, patterns) {
   const b = block(patterns);
-  if (existing.includes(START) && existing.includes(END)) {
+  const startIndex = existing.indexOf(START);
+  const endIndex = existing.indexOf(END, startIndex + START.length);
+  if (startIndex !== -1 && endIndex !== -1) {
     return existing.replace(new RegExp(escape(START) + "[\\s\\S]*?" + escape(END)), b).trimEnd() + "\n";
   }
+  if (startIndex !== -1) {
+    const base = existing.slice(0, startIndex).trim();
+    return (base ? base + "\n\n" : "") + b + "\n";
+  }
   const base = existing.trim();
   return (base ? base + "\n\n" : "") + b + "\n";
 }

test/ctxtrim.test.js

@@ -130,6 +130,22 @@ test("ignore block is idempotent (managed block replaced, user lines kept)", ()
   assert.ok(!second.includes("package-lock.json"), "old managed pattern should be gone");
 });
 
+test("ignore merge repairs a managed block with no end marker", () => {
+  const existing = [
+    "# my own rule",
+    "*.log",
+    "# >>> ctxtrim (managed) >>>",
+    "old-generated-pattern/",
+  ].join("\n");
+
+  const repaired = merge(existing, ["dist/", "coverage/"]);
+
+  assert.ok(repaired.includes("# my own rule\n*.log"));
+  assert.ok(repaired.includes(block(["dist/", "coverage/"])));
+  assert.ok(!repaired.includes("old-generated-pattern/"));
+  assert.equal((repaired.match(/ctxtrim \(managed\)/g) || []).length, 2);
+});
+
 test("clean repo (only source) reports nothing to trim", () => {
   // scanning the src subdir alone = only source
   const s = scanRepo(join(repo, "src"));