fix(agent): keep default prompt paths relative

tests/agent/test_skills_loader.py

@@ -298,7 +298,7 @@ def test_disabled_skills_excluded_from_build_skills_summary(tmp_path: Path) -> N
     assert "beta" in summary
 
 
-def test_build_skills_summary_groups_paths_by_root(tmp_path: Path) -> None:
+def test_build_skills_summary_uses_relative_roots_in_agent_workspace(tmp_path: Path) -> None:
     workspace = tmp_path / "ws"
     workspace_skills = workspace / "skills"
     workspace_skills.mkdir(parents=True)
@@ -308,14 +308,34 @@ def test_build_skills_summary_groups_paths_by_root(tmp_path: Path) -> None:
 
     summary = SkillsLoader(workspace, builtin_skills_dir=builtin).build_skills_summary()
 
-    assert summary.count(str(workspace_skills)) == 1
-    assert summary.count(str(builtin)) == 1
+    assert str(workspace_skills) not in summary
+    assert str(builtin) not in summary
     assert str(workspace_path) not in summary
     assert str(builtin_path) not in summary
+    assert summary.count("(`skills`)") == 2
     assert "`alpha/SKILL.md`" in summary
     assert "`beta/SKILL.md`" in summary
 
 
+def test_build_skills_summary_keeps_absolute_roots_for_selected_project(tmp_path: Path) -> None:
+    workspace = tmp_path / "ws"
+    workspace_skills = workspace / "skills"
+    workspace_skills.mkdir(parents=True)
+    _write_skill(workspace_skills, "alpha", body="# Alpha")
+    builtin = tmp_path / "builtin"
+    _write_skill(builtin, "beta", body="# Beta")
+    project = tmp_path / "project"
+    project.mkdir()
+
+    summary = SkillsLoader(workspace, builtin_skills_dir=builtin).build_skills_summary(
+        workspace=project,
+    )
+
+    assert summary.count(str(workspace_skills.resolve())) == 1
+    assert summary.count(str(builtin.resolve())) == 1
+    assert str(project.resolve()) not in summary
+
+
 def test_bundled_update_setup_description_is_valid_yaml(tmp_path: Path) -> None:
     metadata = SkillsLoader(tmp_path).get_skill_metadata("update-setup")