ha-vledger

Pre-alpha. Do not install this. It captures a raw log and nothing else yet: no trips, no charging sessions, no consumption, no cost. The log format is decided and will be read by every later version, but the integration has run on exactly one vehicle, the options may change between releases, and there is no support. It is public so that the author can test it through HACS and so that the design can be read. When it is ready for other people, this notice goes away.

A vehicle ledger for Home Assistant. It keeps a raw log of the handful of vehicle states that matter to a ledger — odometer, position, fuel level, state of charge, charging state — and derives from it what the vehicle's own app never tells you reliably: trips, charging sessions, refuellings, consumption and cost. Passively, from whatever integration already exposes the vehicle, without a line of manufacturer-specific code, and without touching anything else the vehicle reports: it is a ledger, not a monitor.

Status: capture works. The integration sets up a vehicle or a charge point through the UI, writes its raw log and shows it in numbers as diagnostic entities and diagnostics — the format, and the vledger l0 verbs that write, read, validate and count it and list its gaps, are the library's. The first derivation exists: vledger derive trips finds the trips in a stream, and L1 — the derivation on disk, with its manifest and cursor — is written and read by the l1 verbs. No charging sessions, refuellings, metrics or receipts yet, and the integration does not derive live yet. Every behaviour described below is the design, held as requirements in the project's register (ha-vledger-pm); a section is marked (planned) until it exists.

What it does (planned)

• Captures, losslessly. Every change of a source entity you assign to a role becomes one record in a raw log (L0): JSON Lines, append-only, one stream per vehicle and per charge point, rotated monthly, kept outside the Home Assistant recorder and its retention. Start, stop and heartbeat markers make any capture gap visible; nothing is interpolated across one.
• Derives, deterministically. Trips (between standstills), charging sessions (from the charging state), refuellings (a fuel rise at unchanged odometer) and metrics are computed from L0, receipts and configuration (L1) — the same logic live in Home Assistant and in batch from the command line, recomputable from scratch at any time. Every derived value carries a quality flag: measured, receipt, estimated or incomplete.
• Takes receipts. Price and exact quantity come from you: a refuelling or charging receipt, entered from a notification, a dashboard or an action, matched to the detected event by time. Receipt values beat sensor values; a detected event without a receipt stays visible as unconfirmed.
• Knows your charge points. Home, work, anywhere fixed: position, radius, tariff, optionally a meter. A charge point with a tariff but no meter still yields cost, estimated through a charging loss factor; a tariff of 0 is cost 0. Anything else is a foreign charge and asks for a receipt.
• Reports. Per month, year and rolling period: distance, litres and kWh, fuel and electricity cost, €/100 km per energy carrier, the electric share two ways (energy by heating value, and an estimated distance share), charge cycles and tank-fill equivalents. Fuel consumption is tank-to-tank between any two receipts, corrected by the fuel level sensor, so a tank that is never filled up still gets a figure.

What it is built of

One repository, two packages, one version number (ADR-0002):

src/vledger/               the library and the vledger CLI: all derivation
                           logic, no Home Assistant, no dependencies;
                           published to PyPI as `vledger`
custom_components/vledger/ the Home Assistant integration, a shell over the
                           library: capture, config and options flows,
                           entities, actions, diagnostics; pins the library
                           by the same version in manifest.json
tests/                     pytest: library tests on L0 fixtures, integration
                           tests with pytest-homeassistant-custom-component
docs/                      design documentation

A vehicle is a config entry; its source entities are assigned to roles (odometer, position, fuel_level, soc, charging_state, …), and what the vehicle can do follows from the roles it has. Everything is configured in the UI; no YAML.

Documentation

Decisions, requirements and the work queue are records in the project's register, ha-vledger-pm, not prose here.

Installing

Not yet — see the notice at the top. For the author's own test instances: in HACS, Integrations → ⋮ → Custom repositories, add https://github.com/michael-lenz/ha-vledger as an Integration, then install it and restart; or copy custom_components/vledger into the configuration directory by hand. Either way Home Assistant installs the library from PyPI (vledger==<version>, pinned in the manifest), so the version has to be published first — docs/releasing.md. Then Settings → Devices & services → Add integration → Vehicle Ledger: the user guide walks the four steps. The library on its own: pip install vledger, which brings the vledger command.

Developing

docs/developing.md is the manual; the short form:

python3 -m venv .venv && .venv/bin/pip install -e ".[dev,ha]"
.venv/bin/python -m pytest -q
.venv/bin/ruff check src tests custom_components

The library's tests run in any Python with .[dev]; the integration's need the ha extra and a venv. CLAUDE.md says how a Claude session works here and with the register.

Privacy

The position history is personal data. It stays on your instance — nothing is transmitted anywhere — and is redacted from logs and diagnostics, but the default storage path lies under the Home Assistant configuration directory and is therefore part of your backups.

License

BSD-3-Clause — see LICENSE.