# Refactor Notes: `main.cpp` Split

## Architecture

The firmware remains a unified image. Role selection is still done at boot in `src/main.cpp` using the role pin. `src/main.cpp` is now a thin coordinator that:

- detects role and initializes shared platform subsystems,
- creates role module config,
- calls `begin()` once,
- delegates runtime via `loop()`.

## Sender Logic

Sender-only runtime now lives in:

- `src/sender_state_machine.h`
- `src/sender_state_machine.cpp`

Public API:

- `SenderStateMachineConfig`
- `SenderStats`
- `SenderStateMachine::begin(...)`
- `SenderStateMachine::loop()`
- `SenderStateMachine::stats()`

Sender state machine exposes explicit states (`Syncing`, `Normal`, `Catchup`, `WaitAck`) and keeps sender flow isolated from top-level orchestration.

Sender helpers:

- `handleMeterRead(...)`
- `maybeSendBatch(...)`
- `handleAckWindow(...)`
- `applyTimeFromAck(...)`
- `validateInvariants()`

Sender invariants are checked and debug-traceable (`DD3_DEBUG`) for:

- single inflight batch at a time,
- ACK acceptance only for matching `batch_id`,
- retry bounded by `BATCH_MAX_RETRIES`,
- queue depth bounded by `BATCH_QUEUE_DEPTH`.

## Receiver Logic

Receiver-only runtime now lives in:

- `src/receiver_pipeline.h`
- `src/receiver_pipeline.cpp`

Shared receiver arrays and fault/discovery state used by setup wiring and runtime are held in:

- `src/app_context.h` (`ReceiverSharedState`)

Public API:

- `ReceiverPipelineConfig`
- `ReceiverStats`
- `ReceiverPipeline::begin(...)`
- `ReceiverPipeline::loop()`
- `ReceiverPipeline::stats()`

Receiver pipeline owns LoRa RX processing, reassembly/decode, ACK send path, MQTT/SD/display updates, and receiver fault/discovery publication flow.

## HA Manufacturer Single Source

`include/config.h` defines the canonical manufacturer:

- `HA_MANUFACTURER = "AcidBurns"`

Home Assistant discovery payload generation in `src/mqtt_client.cpp` uses this constant directly (`device["manufacturer"] = HA_MANUFACTURER`).

Drift guards:

- compile-time lock in `include/config.h` via `static_assert`,
- `test/check_ha_manufacturer.ps1` validates discovery assignment and rejects stray hardcoded manufacturer literals in `src/` and `include/`,
- smoke test `test/test_refactor_smoke/test_refactor_smoke.cpp` asserts the constant value and module header compatibility.