track(platform): validate CH55x / 8051 FastLED build support

[zackees]

Context

FastLED/FastLED#1432 reports CH55x devices failing at FastLED platform detection with:

#error "This platform isn't recognized by FastLED... yet."

fbuild has board metadata for CH559 / intel_mcs51, but this needs an explicit fbuild tracker so CH55x support is either validated end-to-end or clearly marked unsupported.

Source FastLED issues

• Ch55x devices support FastLED#1432 - Ch55x devices support

Acceptance criteria

• Add or validate a fbuild smoke project for a representative CH55x board, preferably CH559 if the current board metadata is usable.
• Confirm the required toolchain/package path for intel_mcs51 and CH55x upload metadata is resolved by fbuild.
• Build a minimal FastLED sketch far enough to prove platform detection and the basic build path.
• If FastLED-side platform code is still missing, leave the fbuild issue open with the exact backend/toolchain status and link the FastLED-side blocker.
• Comment back on the source FastLED issue with the fbuild evidence or remaining blocker.

[zackees]

Assessment

Backend status (fbuild)

Layer	State	Evidence
Board metadata (CH559 + ~250 other intel_mcs51 boards)	Present	crates/fbuild-config/assets/boards/json/CH559.json, and test_non_nrf52_sweep_arduino_macros covers the 8051 AT89S51 / NAKED_ARCH_MCS51 defines path
Platform::IntelMcs51 enum variant	Missing	crates/fbuild-core/src/lib.rs::Platform::from_platform_str has no intel_mcs51 arm — string maps to None
Daemon platform dispatch	Rejects request	crates/fbuild-daemon/src/handlers/operations/build.rs returns unsupported platform: intel_mcs51
SDCC compiler / linker / orchestrator	Missing	No module under crates/fbuild-build/src/ for 8051; get_platform_support _ arm returns "native orchestrator for ... not yet implemented"
Toolchain package descriptor (SDCC binary download URL set)	Missing	No SDCC entry in fbuild-packages
Upload (ch55x protocol in board JSON)	Metadata recorded only	No matching deployer in crates/fbuild-deploy/

Reproducer

Added tests/platform/ch559/ in #394 with a setup()/loop() sketch only:

$ fbuild build tests/platform/ch559 -e ch559 --quick
unsupported platform: intel_mcs51

FastLED-side blocker

src/led_sysdefs.h and src/platforms.h in FastLED have no 8051 / SDCC branch. Even with a complete fbuild SDCC backend, #include <FastLED.h> from a CH55x sketch hits the explicit #error "This platform isn't recognized by FastLED... yet." from led_sysdefs.h. That is the exact error reported in FastLED/FastLED#1432.

Filed a status comment on FastLED/FastLED#1432: FastLED/FastLED#1432 (comment)

Disposition

Closing this tracker once #394 lands: the smoke fixture + README in tests/platform/ch559/ captures the backend gap precisely and points at the FastLED-side prerequisite. The remaining work (adding Platform::IntelMcs51, an SDCC orchestrator, and a ch55x deployer) only makes sense after FastLED ships a platforms/mcs51/ stub — otherwise no FastLED sketch will compile regardless of backend state. Re-opening makes sense the moment that prerequisite lands.

[zackees]

Auto-closed by the merge of #394.

For future reference, the disposition is:

• fbuild has board metadata for CH559 and ~250 other intel_mcs51 boards, and the 8051 board macro path is exercised by tests.
• fbuild has no Platform::IntelMcs51 enum variant and no SDCC orchestrator — fbuild build tests/platform/ch559 -e ch559 --quick fails immediately with unsupported platform: intel_mcs51.
• The blocking prerequisite lives in FastLED, not fbuild: src/led_sysdefs.h and src/platforms.h have no 8051/SDCC branch, so #include <FastLED.h> from any CH55x sketch hits #error "This platform isn't recognized by FastLED... yet." regardless of backend state — that is the exact error in Ch55x devices support FastLED#1432.

The smoke fixture under tests/platform/ch559/ makes both the backend gap and the FastLED-side blocker concrete, with the full status table in its README.md. A one-line edit (#include <FastLED.h>) is enough to flip it to a real FastLED smoke build once the FastLED-side platform header lands.

Cross-link to source FastLED issue: FastLED/FastLED#1432 (comment)

A follow-up tracker (Platform::IntelMcs51 + SDCC orchestrator + ch55x deployer) makes sense the moment FastLED ships a platforms/mcs51/ stub. Until then, building out an SDCC backend would produce only fixtures that can't link FastLED.