fix(git): report missing cwd distinctly from missing git binary

A deleted/nonexistent cwd also makes Bun.spawn throw ENOENT; only claim
'git is not installed.' when the working directory actually exists, else
name the missing directory. Addresses the Codex P2 review on #6237.

packages/coding-agent/src/utils/git.ts

@@ -442,7 +442,14 @@ async function git(cwd: string, args: readonly string[], options: CommandOptions
 			windowsHide: true,
 		});
 	} catch (err) {
-		if (isEnoent(err)) return { exitCode: GIT_SPAWN_ENOENT_EXIT_CODE, stdout: "", stderr: "git is not installed." };
+		if (isEnoent(err)) {
+			// A deleted/nonexistent cwd also surfaces as a spawn ENOENT; only blame
+			// the binary when the working directory actually exists.
+			const stderr = fs.existsSync(cwd)
+				? "git is not installed."
+				: `working directory does not exist: ${cwd}`;
+			return { exitCode: GIT_SPAWN_ENOENT_EXIT_CODE, stdout: "", stderr };
+		}
 		throw err;
 	}
 

packages/coding-agent/test/git-missing-binary.test.ts

@@ -33,6 +33,15 @@ describe("git helpers with git binary absent (#6169)", () => {
 		await expect(git.diff.has("/")).rejects.toThrow("git is not installed.");
 	});
 
+	it("does not blame the git binary when the cwd is what is missing", async () => {
+		vi.spyOn(Bun, "spawn").mockImplementation(throwSpawnEnoent);
+		// A deleted cwd also makes spawn throw ENOENT; the error must name the
+		// directory, not falsely claim git is uninstalled.
+		await expect(git.diff.has("/nonexistent-omp-eval-dir")).rejects.toThrow(
+			"working directory does not exist: /nonexistent-omp-eval-dir",
+		);
+	});
+
 	it("repo.root degrades to null instead of throwing ENOENT", async () => {
 		vi.spyOn(Bun, "spawn").mockImplementation(throwSpawnEnoent);
 		expect(await git.repo.root("/")).toBeNull();