fix(store): default store_path when config omits it (issue #53)

Fresh installs shipped a config template with no store_path key while
collector.py demanded one via get_store_path() — every first collect
crashed with KeyError 'store_path'. Resolve to the packaged default
(/var/lib/fenris/observations.db) when absent, document the key in the
template, and cover the fresh-install path with regression tests.
Bump to 0.3.2.

packaging/fenris.conf

@@ -8,4 +8,9 @@
 #
 #   device = /dev/disk/by-id/nvme-Samsung_SSD_980_PRO_500GB_S5PANS0T123456
 #
+# The observation store path is optional and defaults to
+# /var/lib/fenris/observations.db when unset:
+#
+#   store_path = /var/lib/fenris/observations.db
+#
 # See https://git.bongbetic.com/xavierk/Fenris for documentation.

pyproject.toml

@@ -1,6 +1,6 @@
 [project]
 name = "fenris"
-version = "0.3.1"
+version = "0.3.2"
 description = "NVMe wear monitor with persistent TUI"
 requires-python = ">=3.9"
 dependencies = [

src/fenris/store.py

@@ -15,9 +15,19 @@ from typing import Optional
 SCHEMA_VERSION = 1
 
 
+# Packaged default placement (spec §8.3). The config may override it, but a
+# fresh install that sets only the device selector must collect cleanly.
+DEFAULT_STORE_PATH = Path("/var/lib/fenris/observations.db")
+
+
 def get_store_path(config: dict) -> Path:
-    """Get the store path from config."""
+    """Get the store path from config.
-    return Path(config["store_path"])
+
+    Falls back to the packaged default when the config does not pin one,
+    so a fresh install whose config holds only the device selector works
+    instead of crashing with KeyError 'store_path' (issue #53).
+    """
+    return Path(config.get("store_path", DEFAULT_STORE_PATH))
 
 
 def init_store(store_path: Path) -> sqlite3.Connection:

tests/test_store_config.py

@@ -0,0 +1,56 @@
+"""Store path resolution from config — regression coverage for issue #53.
+
+A fresh install ships a placeholder-commented config whose only required
+key is the device selector. The collector must not crash with
+KeyError 'store_path' when the key is absent.
+"""
+import sys
+from pathlib import Path
+
+sys.path.insert(0, str(Path(__file__).parent.parent / "src"))
+
+from fenris.store import DEFAULT_STORE_PATH, get_store_path
+
+
+REPO_ROOT = Path(__file__).resolve().parent.parent
+TEMPLATE = REPO_ROOT / "packaging" / "fenris.conf"
+
+
+def _parse_like_load_config(text: str) -> dict:
+    """Mirror collect.load_config()'s key=value parsing rules."""
+    config = {}
+    for line in text.splitlines():
+        line = line.strip()
+        if not line or line.startswith("#"):
+            continue
+        if "=" in line:
+            key, value = line.split("=", 1)
+            config[key.strip()] = value.strip()
+    return config
+
+
+def test_missing_store_path_falls_back_to_default():
+    """Config with only the device selector resolves to the packaged default."""
+    assert get_store_path({"device": "/dev/nvme0n1"}) == DEFAULT_STORE_PATH
+
+
+def test_explicit_store_path_wins():
+    """An explicit store_path override is honored."""
+    assert get_store_path({"store_path": "/tmp/other.db"}) == Path("/tmp/other.db")
+
+
+def test_packaged_template_yields_collectable_config():
+    """The packaged template, once a device is set, must be collector-ready.
+
+    Reproduces the fresh-install path: parse packaging/fenris.conf the way
+    collect.load_config() does, add the device selector, then resolve the
+    store. Issue #53 made this raise KeyError.
+    """
+    config = _parse_like_load_config(TEMPLATE.read_text())
+    config["device"] = "/dev/nvme0n1"
+    assert get_store_path(config) == DEFAULT_STORE_PATH
+
+
+def test_template_documents_store_path():
+    """The template must mention store_path so admins know it is overridable."""
+    assert "store_path" in TEMPLATE.read_text()