fix: handle missing gh executable

src/github_agent_bridge/dispatch.py

@@ -85,7 +85,11 @@ def __init__(self, gh_bin: str = "gh", mode: RunMode = RunMode.LIVE):
         self.gh_bin = gh_bin
 
     def _run(self, args: list[str]) -> subprocess.CompletedProcess[str]:
-        return subprocess.run([self.gh_bin, *args], check=False, stdout=subprocess.PIPE, stderr=subprocess.PIPE, text=True)
+        command = [self.gh_bin, *args]
+        try:
+            return subprocess.run(command, check=False, stdout=subprocess.PIPE, stderr=subprocess.PIPE, text=True)
+        except FileNotFoundError as exc:
+            return subprocess.CompletedProcess(command, 127, "", str(exc))
 
     def current_login(self) -> str | None:
         result = self._run(["api", "user", "--jq", ".login"])

tests/test_modes_cli.py

@@ -12,6 +12,16 @@ def test_shadow_github_reaction_has_no_external_failure():
     assert GitHubClient(gh_bin="definitely-not-present", mode=RunMode.SHADOW).react_eyes(make_job().context) is True
 
 
+def test_live_github_command_handles_missing_gh_binary():
+    client = GitHubClient(gh_bin="definitely-not-present", mode=RunMode.LIVE)
+
+    result = client._run(["api", "user"])
+
+    assert result.returncode == 127
+    assert result.stdout == ""
+    assert "definitely-not-present" in result.stderr
+
+
 class RecordingGitHubClient(GitHubClient):
     def __init__(self):
         super().__init__(mode=RunMode.LIVE)