docs: clarify Python bridge runtime and test behavior

.memory/state.md

@@ -1,7 +1,7 @@
 # State
 
 ## Current focus
-Read-only TypeScript wrapper around `pykeepass` via a Python JSON bridge.
+Read-only TypeScript wrapper around KeePass `.kdbx` databases through a Python JSON bridge.
 
 ## Current API
 - `openKeePassDatabase(path, options)`
@@ -11,14 +11,18 @@ Read-only TypeScript wrapper around `pykeepass` via a Python JSON bridge.
 - `close()` is a no-op
 
 ## Runtime model
-- TypeScript starts the Python bridge
+- TypeScript spawns Python per request
 - Python uses `pykeepass`
 - JSON is exchanged over stdin/stdout
-- Bridge errors and empty/invalid JSON are surfaced to TypeScript
+- Errors from the bridge, missing files, invalid JSON, and backend exceptions are surfaced to TypeScript
+- Python defaults to `.venv/bin/python3`, overridable with `PYTHON_PATH`
 
 ## Current fixture/test status
 - Bundled fixtures: `tests/fixtures/data.kdbx` and `tests/fixtures/empty.kdbx`
-- Integration tests validate entries, groups, and OTP/TOTP output for `data.kdbx`
+- `tests/fixtures/data.kdbx.json` stores the password and expected tree/content
+- Unit tests mock `node:child_process.spawn`
+- Integration tests validate entries, groups, partial search, and OTP/TOTP output for `data.kdbx`
+- Integration tests skip when `pykeepass` is unavailable
 
 ## Next step
-Keep tightening failure-path coverage and improve the API shape only if needed.
+Keep tightening failure-path coverage and keep the API minimal unless a concrete need appears.