led2/.planning/phases/03-communication-protocol/03-01-SUMMARY.md

phase, plan, subsystem, tags, requires, provides, affects, tech-stack, key-files, key-decisions, duration, completed

phase	plan	subsystem	tags	requires	provides	affects	tech-stack	key-files	key-decisions	duration	completed
03-communication-protocol	01	protocol	udp wled protocol animation led struct asyncio tdd	phase provides 02-audio-engine FastAPI app with lifespan pattern and app.state for shared resources	WLED-compatible DRGB/DRGBW/DNRGB UDP frame encoders Custom 0xAC animation command packet encoder/decoder (16 bytes) UDPSender async transport wrapper (single shared socket) SK6812Device.encode_animation_cmd — real 16-byte packets, not empty stub WS2801Device.encode_animation_cmd — real 16-byte packets, not empty stub	lightsync/protocol/ (new package) lightsync/devices/sk6812.py lightsync/devices/ws2801.py	added patterns TDD RED-GREEN: failing tests committed first, implementation committed to pass them Single shared asyncio DatagramTransport — one socket sends to N device addresses (no socket pool) WLED DRGB/DRGBW: 2-byte header [type, timeout] + RGB/RGBW body per pixel WLED DNRGB: 4-byte header [type, timeout, start_hi, start_lo] + RGB chunks per packet struct.pack('>BBH') for big-endian DNRGB start index (critical per WLED spec) struct.pack('>BBBBf') for 0xAC animation command header + float32 speed _NullProtocol swallows OS UDP errors — fire-and-forget is correct for LED delivery	created modified lightsync/protocol/__init__.py lightsync/protocol/drgb.py lightsync/protocol/animation_cmd.py lightsync/protocol/udp_sender.py tests/__init__.py tests/test_protocol.py lightsync/devices/sk6812.py lightsync/devices/ws2801.py	TDD approach: tests committed as RED before implementation — forces verification of test coverage 0xAC animation command marker chosen well above WLED 0x01-0x04 range — no firmware collision UDPSender uses asyncio DatagramTransport over asyncudp library — no dependency needed, stdlib suffices Device stubs delegate to encode_animation_cmd via import alias _encode_cmd — clean, no code duplication pytest added as dev dependency via uv add --dev pytest — was missing from pyproject.toml	~4min	2026-04-06

Phase 3 Plan 01: Protocol Encoders Summary

WLED-compatible UDP protocol layer implemented — DRGB/DRGBW/DNRGB frame encoders, custom 0xAC animation command packet with full roundtrip, async UDPSender transport, and SK6812/WS2801 device stubs replaced with real 16-byte packets — all tested with 27 passing tests

Performance

• Duration: ~4 min
• Started: 2026-04-06T21:38:29Z
• Completed: 2026-04-06T21:42:37Z
• Tasks: 2 (Task 1 TDD, Task 2 auto)
• Tests: 27 passing

Accomplishments

Task 1: Protocol encoders — DRGB/DRGBW/DNRGB + animation command (TDD)

RED phase: 27 failing tests committed covering all encoder behaviors including byte layout, MTU truncation, DNRGB multi-packet splitting, big-endian start index, animation roundtrip, flags byte, and defaults.

GREEN phase: Implemented lightsync/protocol/drgb.py with:

• encode_drgb: 2-byte header + 3-byte-per-pixel body, truncates at 490 px (MTU)
• encode_drgbw: 2-byte header + 4-byte-per-pixel body, truncates at 367 px (MTU)
• encode_dnrgb_packets: splits at 489 px/packet with big-endian start index via struct.pack(">BBH")

Implemented lightsync/protocol/animation_cmd.py with:

• ANIMATION_IDS and ANIMATION_NAMES dicts mapping 7 animation names to IDs 0-6
• encode_animation_cmd: 16-byte packet (0xAC marker, version, type ID, flags, speed float32, primary/secondary color, white, density)
• decode_animation_cmd: full inverse — roundtrips correctly for all 7 types

All 27 tests pass.

Task 2: UDP sender + device stub completion

Created lightsync/protocol/udp_sender.py:

• _NullProtocol swallows OS-level send errors (UDP delivery is best-effort)
• UDPSender opens single shared DatagramTransport at local_addr=("0.0.0.0", 0)
• send(payload, ip, port) is synchronous fire-and-forget
• start()/stop() async lifecycle methods for FastAPI lifespan integration
• is_running property reflects transport state

Updated lightsync/devices/sk6812.py and ws2801.py:

• Added from lightsync.protocol.animation_cmd import encode_animation_cmd as _encode_cmd
• Replaced return b"" stub with return _encode_cmd(animation, params)
• SK6812: encode_animation_cmd("solid_color", {"color":[255,0,0], "white":128}) → ac0100003f000000ff00000000008000 (16 bytes, starts 0xAC)
• WS2801: encode_animation_cmd("chase", {"color":[0,255,0], "speed":0.7}) → ac0101003f33333300ff000000000000 (16 bytes, starts 0xAC)

Task Commits

1. Task 1 RED: Failing protocol tests — ffc4ef6 (test)
2. Task 1 GREEN: WLED encoders + animation cmd — 5e13da3 (feat)
3. Task 2: UDP sender + device stubs — f17e77f (feat)

Files Created/Modified

• lightsync/protocol/__init__.py — empty package init
• lightsync/protocol/drgb.py — DRGB/DRGBW/DNRGB encoders with WLED constants
• lightsync/protocol/animation_cmd.py — 0xAC animation command encoder/decoder
• lightsync/protocol/udp_sender.py — async UDP transport wrapper
• tests/__init__.py — test package init
• tests/test_protocol.py — 27 tests for protocol correctness
• lightsync/devices/sk6812.py — stub replaced with real encoding
• lightsync/devices/ws2801.py — stub replaced with real encoding

Decisions Made

• TDD approach applied: Tests written and committed as RED before implementation, ensuring coverage is meaningful not retrofitted
• 0xAC marker: Well above WLED 0x01-0x04 range — firmware can dispatch on first byte without ambiguity
• No asyncudp library: Python stdlib asyncio DatagramTransport is sufficient and avoids an extra dependency
• pytest added as dev dep: Was missing from pyproject.toml, added via uv add --dev pytest

Deviations from Plan

Auto-fixed Issues

1. [Rule 3 - Blocking] pytest not installed

• Found during: TDD RED phase (running tests)
• Issue: uv run python -m pytest failed with "No module named pytest"
• Fix: uv add --dev pytest — added to pyproject.toml [project.optional-dependencies] dev section
• Files modified: pyproject.toml (by uv)
• Commit: (included in uv lockfile update before ffc4ef6)

Verification Results

• python -m pytest tests/test_protocol.py -v — 27 passed in 0.04s
• from lightsync.protocol.drgb import encode_drgb, encode_drgbw, encode_dnrgb_packets — imports OK
• from lightsync.protocol.udp_sender import UDPSender — imports OK
• SK6812Device.encode_animation_cmd returns 16-byte 0xAC packet — PASS
• WS2801Device.encode_animation_cmd returns 16-byte 0xAC packet — PASS

Known Stubs

None — all planned stubs replaced with real implementations. The encode_animation_cmd stubs in SK6812Device and WS2801Device that returned b"" are now wired to the real protocol encoder.

Self-Check

Files created/modified:

• lightsync/protocol/init.py — FOUND
• lightsync/protocol/drgb.py — FOUND
• lightsync/protocol/animation_cmd.py — FOUND
• lightsync/protocol/udp_sender.py — FOUND
• tests/init.py — FOUND
• tests/test_protocol.py — FOUND
• lightsync/devices/sk6812.py — FOUND
• lightsync/devices/ws2801.py — FOUND

Commits:

• ffc4ef6 — test(03-01) RED phase
• 5e13da3 — feat(03-01) GREEN phase
• f17e77f — feat(03-01) Task 2

Self-Check: PASSED

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Phase: 03-communication-protocol Completed: 2026-04-06