diff --git a/src/application/use-cases/cleanup-worktrees.test.ts b/src/application/use-cases/cleanup-worktrees.test.ts
index 9b1f0e6..090084c 100644
--- a/src/application/use-cases/cleanup-worktrees.test.ts
+++ b/src/application/use-cases/cleanup-worktrees.test.ts
@@ -330,6 +330,31 @@ describe("cleanupWorktrees", () => {
 		});
 	});
 
+	test("branch deletion failure surfaces as error report", async () => {
+		// Unmerged branch → force fallback. Stub deleteBranchForce to fail so the
+		// delete-branch use case returns `failed`, which cleanup must surface as
+		// an `error` report.
+		const baseGit = createFakeGit({
+			worktrees: [mainWt, featureA],
+			branches: ["main", "feature-a"],
+			goneBranches: ["feature-a"],
+			mergedBranches: [],
+			commitCountMap: new Map([["main..feature-a", 3]]),
+		});
+		const git = {
+			...baseGit,
+			async deleteBranchForce(_branch: string) {
+				return { success: false as const, error: { code: "UNKNOWN" as const, message: "force boom" } };
+			},
+		};
+		const output = expectOk(await cleanupWorktrees({ force: true, dryRun: false }, { git }));
+
+		expect(output.reports[0]).toMatchObject({
+			branch: "feature-a",
+			result: { status: "error", message: "force boom" },
+		});
+	});
+
 	test("default branch is never cleaned", async () => {
 		const git = createFakeGit({
 			worktrees: [mainWt],
diff --git a/src/application/use-cases/cleanup-worktrees.ts b/src/application/use-cases/cleanup-worktrees.ts
index 09cd0e9..837ff84 100644
--- a/src/application/use-cases/cleanup-worktrees.ts
+++ b/src/application/use-cases/cleanup-worktrees.ts
@@ -1,6 +1,7 @@
 import type { GitPort } from "../../domain/ports/git-port.ts";
 import { Result as R, type Result } from "../../shared/result.ts";
 import { classifyGoneBranch } from "./classify-gone-branch.ts";
+import { deleteBranch } from "./delete-branch.ts";
 import { isFullyMerged } from "./is-fully-merged.ts";
 
 export interface CleanupWorktreesInput {
@@ -86,33 +87,37 @@ export async function cleanupWorktrees(
 			}
 		}
 
-		const deleteResult = await git.deleteBranch(branch);
-		if (!deleteResult.success) {
-			if (deleteResult.error.code === "BRANCH_NOT_MERGED") {
-				const forceResult = await git.deleteBranchForce(branch);
-				if (!forceResult.success) {
-					reports.push({
-						branch,
-						worktreePath,
-						result: { status: "error", message: forceResult.error.message },
-					});
-					return;
-				}
-			} else {
+		// Mapping:
+		// - `deleted`     → existing `cleaned` / `branch-only` report.
+		// - `failed`      → `error` report carrying the git error message.
+		// - `not-merged`  → unreachable because we pass `force: true`. Handled
+		//                   defensively so a future contract change in
+		//                   `deleteBranch` doesn't silently report a non-deleted
+		//                   branch as `cleaned`.
+		const outcome = await deleteBranch({ branch, force: true, deleteRemote: false }, { git });
+		switch (outcome.status) {
+			case "deleted":
 				reports.push({
 					branch,
 					worktreePath,
-					result: { status: "error", message: deleteResult.error.message },
+					result: { status: worktree ? "cleaned" : "branch-only" },
+				});
+				return;
+			case "failed":
+				reports.push({
+					branch,
+					worktreePath,
+					result: { status: "error", message: outcome.message },
+				});
+				return;
+			case "not-merged":
+				reports.push({
+					branch,
+					worktreePath,
+					result: { status: "error", message: `Branch "${branch}" is not fully merged` },
 				});
 				return;
-			}
 		}
-
-		reports.push({
-			branch,
-			worktreePath,
-			result: { status: worktree ? "cleaned" : "branch-only" },
-		});
 	};
 
 	if (goneBranches.length > 0) {