diff --git a/packages/loopover-engine/src/miner/worktree-plan.ts b/packages/loopover-engine/src/miner/worktree-plan.ts
index e052ad074c..b8ff54a9b5 100644
--- a/packages/loopover-engine/src/miner/worktree-plan.ts
+++ b/packages/loopover-engine/src/miner/worktree-plan.ts
@@ -42,7 +42,12 @@ function slugifyAttemptId(attemptId: string): string {
     .replace(/[^a-z0-9._-]+/g, "-")
     .replace(/^[-.]+|[-.]+$/g, "");
   if (!slug) throw new Error("invalid_attempt_id");
-  return slug.slice(0, MAX_SLUG_LENGTH);
+  // Re-trim the TRAILING separators AFTER truncation: `.` survives the character-class replace and is a
+  // valid interior char, so slicing to MAX_SLUG_LENGTH can leave a trailing `.`/`-` that the pre-truncation
+  // trim never saw -- git rejects a ref ending in `.` (#7528). Only the trailing edge needs re-trimming: the
+  // pre-truncation trim already removed any leading separators, and slice(0, n) never introduces a new leading
+  // one, so the truncated slug always keeps its non-separator first char (never empties).
+  return slug.slice(0, MAX_SLUG_LENGTH).replace(/[-.]+$/g, "");
 }
 
 /**
diff --git a/test/unit/worktree-plan.test.ts b/test/unit/worktree-plan.test.ts
index 0cd45fc484..08575ecdd6 100644
--- a/test/unit/worktree-plan.test.ts
+++ b/test/unit/worktree-plan.test.ts
@@ -41,6 +41,24 @@ describe("planWorktree (#4269)", () => {
   it("rejects an attempt id that sanitizes to nothing", () => {
     expect(() => planWorktree({ repoPath: "/repo", attemptId: "  ---  " })).toThrow(/invalid_attempt_id/);
   });
+
+  it("REGRESSION (#7528): re-trims after truncation so a `.` landing on the 64-char boundary is not left trailing", () => {
+    // Slug is 63 'a's + '.' + 10 'b's (all survive the character class). Slicing to 64 keeps 63 'a's + '.',
+    // which would end in '.' -- a ref git rejects (`fatal: invalid reference`) -- unless we re-trim after slicing.
+    const attemptId = `${"a".repeat(63)}.${"b".repeat(10)}`;
+    const plan = planWorktree({ repoPath: "/repo", attemptId });
+    expect(plan.branchName).toBe(`${WORKTREE_BRANCH_PREFIX}${"a".repeat(63)}`);
+    expect(plan.branchName.endsWith(".")).toBe(false);
+    expect(plan.branchName.endsWith("-")).toBe(false);
+  });
+
+  it("REGRESSION (#7528): a trailing `-` landing exactly on the boundary is likewise re-trimmed", () => {
+    // Same boundary case with '-' rather than '.', confirming both separators are handled post-truncation.
+    const attemptId = `${"a".repeat(63)}-${"b".repeat(10)}`;
+    const plan = planWorktree({ repoPath: "/repo", attemptId });
+    expect(plan.branchName).toBe(`${WORKTREE_BRANCH_PREFIX}${"a".repeat(63)}`);
+    expect(plan.branchName.endsWith("-")).toBe(false);
+  });
 });
 
 describe("addWorktree", () => {