release: zero-byte db files are corrupt and untouched; README describes 0.2.0 deliverables

- preflight now treats an existing zero-byte file as corrupt (retryable
  refusal, file left at zero bytes) instead of silently initializing
  over it; regression test added
- README overview updated for 0.2.0: database, schema, migrations,
  DAOs, append-only events, and corrupt-file startup behavior

README.md

@@ -4,7 +4,7 @@ Home Assistant custom integration for managing chores, custody schedules, and ho
 
 ## Overview
 
-NestQuest helps households coordinate daily life, chore tracking, custody schedules, and shared tasks directly within Home Assistant. Version 0.1.0 is the integration foundation: a configuration scaffold providing the package and manifest, shared constants, a single-instance config flow, setup/unload lifecycle handling with an options-reload listener, an options flow (horizon days, day rollover time, panel idle timeout), SQLite storage-path resolution, and HACS metadata. Sensors, calendar events, and service calls are forthcoming in later releases and are not yet part of the integration.
+NestQuest helps households coordinate daily life, chore tracking, custody schedules, and shared tasks directly within Home Assistant. Version 0.2.0 ships the integration foundation (a configuration scaffold providing the package and manifest, shared constants, a single-instance config flow, setup/unload lifecycle handling with an options-reload listener, an options flow for horizon days / day rollover time / panel idle timeout, and HACS metadata) plus its persistence layer: an integration-owned SQLite database (`nestquest.db`) with WAL mode and foreign keys, a versioned migration runner stamping schema version 1 across eight tables (children, admin_users, schedule_rules, task_definitions, presence_schedules, presence_overrides, task_instances, completion_events), typed DAO layers so no other feature writes raw SQL, an append-only completion-event log, and startup handling that creates a missing database, opens a valid one, and refuses — without touching a single byte — to start on a corrupt one. Sensors, calendar events, and service calls are forthcoming in later releases and are not yet part of the integration.
 
 ## Installation
 

RELEASE_NOTES.md

@@ -10,7 +10,7 @@ Second release of NestQuest, shipping Feature 02 — the persistence layer the i
 - Schema v1 for all eight tables: `children`, `admin_users`, `schedule_rules`, `task_definitions`, `presence_schedules`, `presence_overrides`, `task_instances`, `completion_events` — validated by declarative CHECK constraints (no triggers).
 - Versioned migration runner: on first start the database is created at schema version 1; later starts are a verified no-op; a failed migration rolls back to its prior version. A database stamped with a future version refuses to start.
 - Typed DAO layers for every table so no other feature writes raw SQL. Assignment validation is atomic; `completion_events` is strictly append-only — the DAO exposes no update or delete method, and a package-wide guard keeps mutation SQL out of every module.
-- Startup handling for missing (created fresh), valid (opened), and corrupt (logged, retried, left byte-identical for backup restore) database files via a read-only `integrity_check` preflight that cannot write or create sidecars.
+- Startup handling for missing (created fresh), valid (opened), and corrupt (logged, retried, left byte-identical for backup restore) database files via a read-only `integrity_check` preflight that cannot write or create sidecars. An existing zero-byte file is treated as corrupt and left untouched, not silently initialized.
 
 ### Requirements
 

custom_components/nestquest/__init__.py

@@ -80,8 +80,17 @@ async def _preflight_existing_file(
     def _probe() -> None:
         # The file-state check and URI construction live inside the
         # executor job: exists/stat/resolve are disk I/O.
-        if not db_path.exists() or db_path.stat().st_size == 0:
+        if not db_path.exists():
             return
+        # A zero-byte file is neither missing nor a valid database: it
+        # is a corrupt (truncated-to-nothing) existing file, likely an
+        # interrupted first write.  The leave-untouched contract applies
+        # to it too: refuse rather than silently initialize over it.
+        if db_path.stat().st_size == 0:
+            raise sqlite3.DatabaseError(
+                "existing database file is empty (zero bytes): file is "
+                "not a database"
+            )
         # Properly escape the path: '#'/'?'/'%' in a directory or file
         # name would otherwise be parsed as URI fragments/parameters/
         # escapes.  immutable=1: SQLite guarantees no writes and no

tests/test_startup_db.py

@@ -124,6 +124,24 @@ def test_missing_file_opens_fresh(tmp_path) -> None:
         _run(database.close())
 
 
+def test_zero_byte_existing_file_is_corrupt_and_untouched(tmp_path) -> None:
+    """A zero-byte file is neither missing nor valid: it is corrupt.
+
+    The leave-untouched contract applies — startup refuses (retryable)
+    rather than silently initializing over whatever interrupted write
+    left the empty file, and the file stays exactly zero bytes.
+    """
+    db_path = tmp_path / "nestquest.db"
+    db_path.write_bytes(b"")
+    with pytest.raises(ConfigEntryNotReady) as excinfo:
+        _run(_async_open_database(_make_hass_mock(), db_path))
+    assert db_path.stat().st_size == 0
+    assert isinstance(excinfo.value.__cause__, sqlite3.DatabaseError)
+    # No sidecars appeared from the refusal path.
+    assert not (tmp_path / "nestquest.db-wal").exists()
+    assert not (tmp_path / "nestquest.db-shm").exists()
+
+
 def test_valid_file_opens_and_migrations_noop(tmp_path) -> None:
     db_path = tmp_path / "nestquest.db"
     _valid_database(db_path)