fix(cli): preserve configurations when confirmed saves fail

ifixai/cli/config_file.py

@@ -7,6 +7,8 @@
 import yaml
 from pydantic import BaseModel, ValidationError
 
+from ifixai.cli.reports import _write_report_atomic
+
 CONFIG_FILENAME = "ifixai.yaml"
 
 
@@ -66,7 +68,8 @@ def load_config(start_dir: Path | None = None) -> RunConfig | None:
 
 
 def write_config(config: RunConfig, start_dir: Path | None = None) -> Path:
-    """Write ``config`` to ``ifixai.yaml`` and return the path."""
+    """Atomically save ``config`` to ``ifixai.yaml`` and return its requested path."""
     path = config_path(start_dir)
-    path.write_text(config.to_yaml(), encoding="utf-8")
+    # Keep linked configurations linked while replacing their resolved target.
+    _write_report_atomic(path.resolve(), config.to_yaml())
     return path

ifixai/tests/test_config_atomic_save.py

@@ -0,0 +1,114 @@
+"""Failed wizard saves must retain the previous reusable configuration."""
+
+import errno
+import json
+import os
+import stat
+import subprocess
+import sys
+from pathlib import Path
+
+import pytest
+
+from ifixai.cli.config_file import RunConfig, load_config, write_config
+
+_LIMITED_SAVE = '''
+import json, resource, signal, sys
+from pathlib import Path
+from ifixai.cli.config_file import RunConfig, write_config
+config = RunConfig(provider="mock", fixture="default", name="new configuration " * 30)
+signal.signal(signal.SIGXFSZ, signal.SIG_IGN)
+resource.setrlimit(resource.RLIMIT_FSIZE, (128, 128))
+try:
+    write_config(config, Path(sys.argv[1]))
+except OSError as exc:
+    print(json.dumps({"errno": exc.errno}))
+else:
+    print(json.dumps({"errno": None}))
+'''
+
+
+def _config_paths(tmp_path, linked):
+    project = tmp_path / "project"
+    project.mkdir()
+    requested = project / "ifixai.yaml"
+    if not linked:
+        return project, requested, requested
+    target = tmp_path / "shared" / "real.yaml"
+    target.parent.mkdir()
+    intermediate = tmp_path / "shared" / "linked.yaml"
+    try:
+        intermediate.symlink_to(target.name)
+        requested.symlink_to(intermediate)
+    except OSError:
+        pytest.skip("This host does not allow fixture symlinks")
+    return project, requested, target
+
+
+@pytest.mark.parametrize("linked", [False, True])
+def test_native_failed_save_retains_config_and_can_retry(tmp_path, linked):
+    pytest.importorskip("resource")
+    project, requested, target = _config_paths(tmp_path, linked)
+    previous = RunConfig(provider="mock", fixture="default", name="previous")
+    original = previous.to_yaml().encode()
+    target.write_bytes(original)
+    target.chmod(0o640)
+    env = os.environ.copy()
+    env["PYTHONDONTWRITEBYTECODE"] = "1"
+    env["PYTHONPATH"] = os.pathsep.join(
+        [str(Path(__file__).parents[2]), env.get("PYTHONPATH", "")]
+    )
+    result = subprocess.run(
+        [sys.executable, "-c", _LIMITED_SAVE, str(project)],
+        cwd=tmp_path, env=env, capture_output=True, text=True, timeout=30, check=True,
+    )
+    assert json.loads(result.stdout)["errno"] == errno.EFBIG
+    assert target.read_bytes() == original
+    if os.name == "posix":
+        assert stat.S_IMODE(target.stat().st_mode) == 0o640
+    assert not list(tmp_path.rglob(".ifixai-report-*.tmp"))
+    if linked:
+        assert requested.is_symlink()
+    replacement = RunConfig(provider="mock", fixture="default", name="retry")
+    assert write_config(replacement, project) == requested
+    assert load_config(project) == replacement
+    if os.name == "posix":
+        assert stat.S_IMODE(target.stat().st_mode) == 0o640
+    if linked:
+        assert requested.is_symlink()
+
+
+@pytest.mark.parametrize("linked", [False, True])
+def test_successful_save_keeps_requested_path_and_target_mode(tmp_path, linked):
+    project, requested, target = _config_paths(tmp_path, linked)
+    target.write_text("provider: mock\n", encoding="utf-8")
+    target.chmod(0o600)
+    config = RunConfig(provider="mock", fixture="default", name="saved")
+    assert write_config(config, project) == requested
+    assert load_config(project) == config
+    if os.name == "posix":
+        assert stat.S_IMODE(target.stat().st_mode) == 0o600
+    if linked:
+        assert requested.is_symlink()
+
+
+@pytest.mark.skipif(os.name != "posix", reason="POSIX umask and mode bits")
+def test_new_config_keeps_normal_creation_umask(tmp_path):
+    script = '''
+import os, sys
+from pathlib import Path
+from ifixai.cli.config_file import RunConfig, write_config
+os.umask(0o077)
+write_config(RunConfig(provider="mock"), Path(sys.argv[1]))
+'''
+    env = os.environ.copy()
+    env["PYTHONDONTWRITEBYTECODE"] = "1"
+    env["PYTHONPATH"] = os.pathsep.join(
+        [str(Path(__file__).parents[2]), env.get("PYTHONPATH", "")]
+    )
+    subprocess.run(
+        [sys.executable, "-c", script, str(tmp_path)],
+        cwd=tmp_path, env=env, capture_output=True, text=True, timeout=30, check=True,
+    )
+    assert stat.S_IMODE((tmp_path / "ifixai.yaml").stat().st_mode) == 0o600
+    assert load_config(tmp_path) == RunConfig(provider="mock")