feat: field validation helpers

Add validation functions for config parameters: valid_time() for HH:MM
format (0-23:0-59), valid_temperature() for Kelvin range 1000-20000,
and valid_gamma() for gamma range 0.0-2.0. These are used by the UI
before saving config changes.

Co-Authored-By: Claude Opus 4.8 <noreply@anthropic.com>

2 files changed, 39 insertions, 0 deletions

diff --git a/hyprsunset_qt/config.py b/hyprsunset_qt/config.py
index a718861..8001f29 100644
--- a/hyprsunset_qt/config.py
+++ b/hyprsunset_qt/config.py
@@ -99,3 +99,18 @@ def write_config(profiles: list[Profile], path: Path = CONFIG_PATH) -> None:
     path = Path(path)
     path.parent.mkdir(parents=True, exist_ok=True)
     path.write_text(serialize(profiles))
+
+
+_TIME_RE = re.compile(r"^([01]?\d|2[0-3]):([0-5]\d)$")
+
+
+def valid_time(s: str) -> bool:
+    return bool(_TIME_RE.match(s))
+
+
+def valid_temperature(t: int) -> bool:
+    return 1000 <= t <= 20000
+
+
+def valid_gamma(g: float) -> bool:
+    return 0.0 <= g <= 2.0
diff --git a/tests/test_config.py b/tests/test_config.py
index 1847449..3a17c8e 100644
--- a/tests/test_config.py
+++ b/tests/test_config.py
@@ -66,3 +66,27 @@ def test_write_then_read(tmp_path):
 
 def test_default_path_is_hypr_conf():
     assert str(CONFIG_PATH).endswith(".config/hypr/hyprsunset.conf")
+
+
+from hyprsunset_qt.config import valid_time, valid_temperature, valid_gamma
+
+
+def test_valid_time():
+    assert valid_time("19:40")
+    assert valid_time("5:00")
+    assert not valid_time("25:00")
+    assert not valid_time("19:60")
+    assert not valid_time("abc")
+
+
+def test_valid_temperature():
+    assert valid_temperature(5500)
+    assert not valid_temperature(500)
+    assert not valid_temperature(30000)
+
+
+def test_valid_gamma():
+    assert valid_gamma(0.8)
+    assert valid_gamma(0.0)
+    assert not valid_gamma(-1.0)
+    assert not valid_gamma(2.5)