# Hendi remote-control lockout findings

Reproduced and verified on real hardware using `scripts/hendi_ctrl_app.py`'s
`--trigger-error-state`, `--reset` and `--test-heater` flags, across two
firmware versions (`getSoftwareVersion()` / `I?`+`V?` via
`components/actor/hendiCtrl.py`).

## Trigger

Calling `remoteEnable(True)` (`R1`) and then disconnecting/exiting without a
matching `remoteEnable(False)` (`R0`) - i.e. an ungraceful disconnect while
remote control is enabled - puts the device into a locked-out state.

## Recovery attempts - v1.12 vs v1.14

v1.14 flashed via `--update-firmware HendiCtrl_0114.srec`;
`getSoftwareVersion()` confirmed `v1.14` afterward.

| Recovery method | Mechanism | v1.12 (original) | v1.14 (firmware fix) |
|---|---|---|---|
| Plain reconnect, no `--reset` | Fresh serial connection only, no DTR/RTS toggle | **Fails** | **Fails** - unchanged, a bare reconnect alone still does not clear the lockout |
| `--reset`, isolated process | Soft reset via DTR/RTS toggle, no power loss | **Fails** (one fluke recovery when combined with `--test-heater` in the *same* process/connection - not reproducible in isolation) | **Recovers** - reproducible across two independent trigger/reset/verify cycles |
| Physical power cycle (device knob) | Full power-off/on of the unit | **Recovers** | Not retested on v1.14 (superseded by `--reset` working) |

## Symptom while locked out

- `I?` / `V?` (software identifier/version queries) still respond normally.
- `R1` (`remoteEnable(True)`) fails with a communication error - this is the
  only observed symptom, and it blocks any command path that needs remote
  control enabled (e.g. `--test-heater`).

## Conclusion

On firmware v1.12, only a physical power cycle clears the lockout; neither a
serial soft-reset nor a fresh serial reconnect does reliably.

**Firmware v1.14 fixes this partially**: a soft reset (`--reset`, i.e.
toggling the DTR/RTS line) now reliably clears the lockout, confirmed across
two independent trigger/reset/verify cycles - no physical power cycle
needed. However, a plain reconnect *without* `--reset` still does not clear
it, so the fix specifically ties recovery to the DTR/RTS reset line rather
than to any new connection.