Add CLAUDE.md with setup, data model and test notes

Co-Authored-By: Claude Opus 5.5 <noreply@anthropic.com>

CLAUDE.md

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+# Wake Up Light II notes
+
+ESPHome firmware for a Moes Wake Up Light II (Tuya PID `ya39qahrcdhvxowz`), running fully local. This repo is public, so never commit secrets, Wi-Fi details or device keys.
+
+## Layout
+
+- `wake-up-light-ii.yaml`: main config.
+- `alarm_block.yaml`: controls for one alarm, included 4 times.
+- `alarm_day.yaml`: one weekday switch, included 7 times per alarm.
+- `components/uart`: ESPHome 2026.10.2's UART component with `patches/wbr3-pa13-pa14-uart.patch` applied. Recheck it when ESPHome updates.
+- `server-example.yaml`: the short YAML that goes on an ESPHome server.
+- `secrets.yaml`: local only, ignored by git. Needs `wifi_ssid`, `wifi_password`, `ap_password`, `api_encryption_key`.
+
+## Releasing
+
+1. Set the `ref` in `wake-up-light-ii.yaml`'s `external_components` to the new tag, then commit and tag that commit.
+2. Push the branch and the tag. On the owner's PC the first push can fail authentication, and a second try works.
+3. Update `ref` in the server's YAML, then press Install. OTA works, and the lamp restarts by itself.
+
+Build from a short folder path: Windows path limits break the libsodium build otherwise.
+
+## Hardware
+
+- WBR3 module (RTL8720CF, 2 MiB flash), talking TuyaMCU at 9600 8N1 on PA13 (RX) and PA14 (TX).
+- Knock sensor: a switch between 3.3V and PA18, using the internal pull-down.
+- UART flashing needs the module desoldered, because PA00 is on the underside. Adapter TX to PA15, RX to PA16, plus GND and a solid 3.3V. Hold PA00 at 3.3V, then tap CEN to GND. PA13 must not be pulled low.
+- Serial reads with `ltchiptool` run at about 3 KB/s, so a full 2 MiB backup takes about 16 minutes.
+- If the serial port says "access denied", another app has it. On the owner's PC that was SignalRGB.
+
+## Data model
+
+From Tuya's definition for a sibling product (tuya-local issue #3821). See the README's corrections section for the byte layouts of DP127, DP128 and DP107.
+
+| DP | Meaning |
+|---|---|
+| 101, 102 | Main light, brightness 10-1000 |
+| 103 | Clock, ASCII HHMMSS |
+| 104 | Display: 0 off, 1 day, 2 night, 3 auto |
+| 105, 106 | Radio on, volume 1-16 |
+| 107 | Stations found, current station |
+| 109, 122, 123, 124 | Alarms 1 to 4 on |
+| 116, 117 | Snooze minutes 8-15, snooze action enum |
+| 121, 128 | Sunset on, sunset settings |
+| 125 | Online time sync |
+| 126 | Radio scan |
+| 127 | Alarm settings, 48 bytes on this unit |
+| 129, 132 | Ambient light on, colour enum |
+| 130 | Snooze |
+| 131 | 24-hour clock |
+
+## Observed behaviour
+
+- A raw UART capture of a ring, radio, scan and sunset showed only heartbeats and normal datapoint frames. No other message types, and no datapoints beyond these 22.
+- There is no "ringing" datapoint. A ring starts with DP101, 105, 121, 129 and 130 all OFF in one burst (3 of 3 rings). Arming an alarm inside its sunrise window sends only DP101, 121 and 129.
+- The stop and volume buttons send nothing to the chip, and neither did the window where a ring should have stopped by itself. So a hand-stopped alarm can't be detected without extra hardware.
+- A knock during a ring snoozes it. DP130 then stays ON. Outside an alarm it returns to OFF at once.
+- DP127 writes are ignored while an alarm is snoozed.
+- A mode without light sets brightness to 0, and a light mode with brightness 0 falls back to no light, so the firmware sets a level when choosing a light mode.
+- Alarm radio stations were reset to 1 while no stations were saved.
+- Radio Volume writes were rejected with the radio off.
+- Keep `default_transition_length` at 0. A transition sends about 50 MCU writes a second.
+- LibreTiny before v1.14.0 can hang after a software restart or OTA until powered off for about 30 seconds (LibreTiny issue #396). The config pins v1.14.0. Drop the pin once ESPHome defaults to it or newer.
+- "Last Restart Reason" reports Power-On even after software restarts.
+
+## Status
+
+Verified:
+- Alarm and sunset settings are echoed by the MCU.
+- Wednesday-only rang on a Wednesday, which fits bit 0 = Monday. A Tuesday-only silent test was skipped.
+- Sunset starts and stops. Its sound was heard, and a glow was seen but not clearly caused by it.
+- A manual scan found 2 stations, while a scan started from the firmware found 0.
+
+Not tested:
+- Radio alarms, Radio Station changes and Radio Volume with the radio on.
+- Bedtime Fade and double knock on the real light.
+- Whether Ambient Color and Snooze Action labels match what the lamp does.
+
+Decided against for now: an Alarm Ringing sensor, and a web UI password.