1	# Building and Flashing the Beyond MCU Firmware (headless)
2
3	The official build is **Microchip Studio** (open `Beyond_Synaptics.atsln`). But
4	the firmware also builds **fully headless** via the CMake/Ninja setup on the
5	`build-cmake` branch + an `arm-none-eabi-gcc` toolchain — no Studio needed. This
6	is the path used to build, package, and flash the M5 doze firmware (0.4.x).
7	Everything below was verified on Windows (HFENDULEAM), 2026-06.
8
9	## Toolchain (one-time install)
10
11	```
12	winget install --id Arm.ArmGnuToolchain   # arm-none-eabi-gcc 12.2 (~224 MB)
13	winget install --id Ninja-build.Ninja
14	python -m pip install crc                  # for the packager scripts
15	```
16
17	arm-gcc lands at (note the spaces — quote it):
18	`C:\Program Files (x86)\Arm GNU Toolchain arm-none-eabi\12.2 mpacbti-rel1\bin`
19	winget does **not** add either to PATH; prepend both for the build shell:
20
21	```bash
22	export PATH="/c/Program Files (x86)/Arm GNU Toolchain arm-none-eabi/12.2 mpacbti-rel1/bin:$LOCALAPPDATA/Microsoft/WinGet/Links:$PATH"
23	```
24
25	## Build
26
27	The CMake files (`CMakeLists.txt`, `CMakePresets.json`, `arm-gcc-toolchain.cmake`,
28	`utils.cmake`) come from the `build-cmake` branch. **Build Release**, not Debug:
29
30	```bash
31	cmake --preset arm-gcc-toolchain.cmake -DCMAKE_BUILD_TYPE=Release
32	cmake --build out/build/arm-gcc-toolchain.cmake
33	# -> out/build/arm-gcc-toolchain.cmake/beyond_synaptics.{elf,bin,hex}
34	```
35
36	Output app is ~75 KB; the app region is ~500 KB, so size is a non-issue.
37
38	### Gotchas (all hit + fixed once; here so you don't rediscover them)
39
40	- **Build Release (`-O3`), not the preset's default Debug (`-Og`).** Studio ships
41	  `-O3`. Under Debug, the non-`static` `inline` helpers in `Devices/tundra_uart.h`
42	  (`circular_buffer_get/put`) are not inlined and have no external definition →
43	  link error `undefined reference to circular_buffer_get`. `-O3` inlines them away.
44	- **Project include dirs must precede the ASF/CMSIS dirs.** The samg55 CMSIS tree
45	  ships its own `component/adc.h` + `instance/adc.h`; if those `-I` dirs come first,
46	  a bare `#include "adc.h"` resolves to the CMSIS one and shadows
47	  `src/Drivers/adc.h` → a cascade of "unknown type `USB_Flip_State_t`" /
48	  "implicit declaration of `init_adc`/`get_cc1_val`". Fix in `CMakeLists.txt`:
49	  list `src/Devices/ src/Drivers/ src/config/ src/crash_handler/` right after `src/`.
50	- **The `build-cmake` source list drifts from `main`.** Reconcile against the
51	  authoritative `.cproj` `<Compile Include=...>` list. Known deltas fixed:
52	  `adc_driver.c` → `adc.c`, add `Devices/tundra_uart.c`.
53	- FPU + libm are available (`-mfpu=fpv4-sp-d16`, links `m`), so `powf` etc. work
54	  in tasks (the doze gamma sweep uses it). `printf` is `iprintf` — no float
55	  *formatting*, but float *math* is fine.
56
57	## Package
58
59	Two-step, mirroring the `.cproj` post-build event. `{VERSION}` = MAJOR+MINOR+PATCH
60	from `sw_ver.h` (e.g. 0.4.1 -> "041"). Run from `scripts/`, use **absolute** output
61	paths (the packager's naive `.split('.')` mangles leading `../` paths):
62
63	```bash
64	# 1. raw .hex -> AppImage (embeds app length @0x400 + CRC32 the bootloader
65	#    verifies on boot; emits both .hex and .bin)
66	py usb_fw_packager_cli.py -o "<abs>/dist/Beyond_AppImage_v041.hex" "<abs>/out/build/arm-gcc-toolchain.cmake/beyond_synaptics.hex"
67
68	# 2. AppImage -> .beyondfw (version header + start addr + binary + SHA512;
69	#    the format the Beyond Utility / quick-beyond-updater flashes). Accepts .hex.
70	py utility_fw_packager_cli.py -v 0.4.1 "<abs>/dist/Beyond_AppImage_v041.hex" "<abs>/dist/latest.beyondfw"
71	```
72
73	`.beyondfw` layout: `[vlen:1][version ascii][start_addr:4 LE][binlen:4 LE][binary][sha512:64]`.
74	Sanity-check against `../quick-beyond-updater/override-*.beyondfw` (same start
75	`0x404000`, same structure).
76
77	## Flash (headless)
78
79	Use the canonical `quick-beyond-updater/bs_hmd_tools.py` API. HID IDs: app =
80	`35BD:0101`, bootloader = `35BD:4004`. Flashing the **AppImage** leaves the
81	bootloader untouched → always recoverable (a bad app just fails its boot CRC and
82	stays in the bootloader, re-flashable).
83
84	```python
85	import sys, os; sys.path.insert(0, r"...\quick-beyond-updater"); os.chdir(r"...\quick-beyond-updater")
86	import hid, bs_hmd_tools as t
87	payload = t.load_beyondfw_file(r"...\dist\latest.beyondfw")     # verifies SHA512
88	bl = t.enter_hmd_bootloader(device_path=<app_path>)             # app -> bootloader, returns boot path
89	t.update_hmd_firmware(firmware_payload=payload, bootloader_path=bl, reset_when_done=True)
90	# verify: t.get_hmd_fw_version(device_path=<app_path_after_reboot>) -> "0.4.1"
91	```
92
93	### **Known flash quirk — always retry**
94
95	The first programming attempt **reliably fails mid-write** around address
96	`0x00404Axx` with `code 46` (a transient HID write glitch). A second attempt —
97	targeting the **bootloader directly** (the device is already in bootloader after
98	the failed attempt) — succeeds every time. Always wrap the flash in a 2-4×
99	retry loop that re-targets `35BD:4004`. See `dist/reflash_doze.py` for a working
100	retry+verify driver. (Root cause unknown; worth a real look someday, not blocking.)
101

# Building and Flashing the Beyond MCU Firmware (headless)

The official build is **Microchip Studio** (open `Beyond_Synaptics.atsln`). But
the firmware also builds **fully headless** via the CMake/Ninja setup on the
`build-cmake` branch + an `arm-none-eabi-gcc` toolchain — no Studio needed. This
is the path used to build, package, and flash the M5 doze firmware (0.4.x).
Everything below was verified on Windows (HFENDULEAM), 2026-06.

## Toolchain (one-time install)

```
winget install --id Arm.ArmGnuToolchain   # arm-none-eabi-gcc 12.2 (~224 MB)
winget install --id Ninja-build.Ninja
python -m pip install crc                  # for the packager scripts
```

arm-gcc lands at (note the spaces — quote it):
`C:\Program Files (x86)\Arm GNU Toolchain arm-none-eabi\12.2 mpacbti-rel1\bin`
winget does **not** add either to PATH; prepend both for the build shell:

```bash
export PATH="/c/Program Files (x86)/Arm GNU Toolchain arm-none-eabi/12.2 mpacbti-rel1/bin:$LOCALAPPDATA/Microsoft/WinGet/Links:$PATH"
```

## Build

The CMake files (`CMakeLists.txt`, `CMakePresets.json`, `arm-gcc-toolchain.cmake`,
`utils.cmake`) come from the `build-cmake` branch. **Build Release**, not Debug:

```bash
cmake --preset arm-gcc-toolchain.cmake -DCMAKE_BUILD_TYPE=Release
cmake --build out/build/arm-gcc-toolchain.cmake
# -> out/build/arm-gcc-toolchain.cmake/beyond_synaptics.{elf,bin,hex}
```

Output app is ~75 KB; the app region is ~500 KB, so size is a non-issue.

### Gotchas (all hit + fixed once; here so you don't rediscover them)

- **Build Release (`-O3`), not the preset's default Debug (`-Og`).** Studio ships
  `-O3`. Under Debug, the non-`static` `inline` helpers in `Devices/tundra_uart.h`
  (`circular_buffer_get/put`) are not inlined and have no external definition →
  link error `undefined reference to circular_buffer_get`. `-O3` inlines them away.
- **Project include dirs must precede the ASF/CMSIS dirs.** The samg55 CMSIS tree
  ships its own `component/adc.h` + `instance/adc.h`; if those `-I` dirs come first,
  a bare `#include "adc.h"` resolves to the CMSIS one and shadows
  `src/Drivers/adc.h` → a cascade of "unknown type `USB_Flip_State_t`" /
  "implicit declaration of `init_adc`/`get_cc1_val`". Fix in `CMakeLists.txt`:
  list `src/Devices/ src/Drivers/ src/config/ src/crash_handler/` right after `src/`.
- **The `build-cmake` source list drifts from `main`.** Reconcile against the
  authoritative `.cproj` `<Compile Include=...>` list. Known deltas fixed:
  `adc_driver.c` → `adc.c`, add `Devices/tundra_uart.c`.
- FPU + libm are available (`-mfpu=fpv4-sp-d16`, links `m`), so `powf` etc. work
  in tasks (the doze gamma sweep uses it). `printf` is `iprintf` — no float
  *formatting*, but float *math* is fine.

## Package

Two-step, mirroring the `.cproj` post-build event. `{VERSION}` = MAJOR+MINOR+PATCH
from `sw_ver.h` (e.g. 0.4.1 -> "041"). Run from `scripts/`, use **absolute** output
paths (the packager's naive `.split('.')` mangles leading `../` paths):

```bash
# 1. raw .hex -> AppImage (embeds app length @0x400 + CRC32 the bootloader
#    verifies on boot; emits both .hex and .bin)
py usb_fw_packager_cli.py -o "<abs>/dist/Beyond_AppImage_v041.hex" "<abs>/out/build/arm-gcc-toolchain.cmake/beyond_synaptics.hex"

# 2. AppImage -> .beyondfw (version header + start addr + binary + SHA512;
#    the format the Beyond Utility / quick-beyond-updater flashes). Accepts .hex.
py utility_fw_packager_cli.py -v 0.4.1 "<abs>/dist/Beyond_AppImage_v041.hex" "<abs>/dist/latest.beyondfw"
```

`.beyondfw` layout: `[vlen:1][version ascii][start_addr:4 LE][binlen:4 LE][binary][sha512:64]`.
Sanity-check against `../quick-beyond-updater/override-*.beyondfw` (same start
`0x404000`, same structure).

## Flash (headless)

Use the canonical `quick-beyond-updater/bs_hmd_tools.py` API. HID IDs: app =
`35BD:0101`, bootloader = `35BD:4004`. Flashing the **AppImage** leaves the
bootloader untouched → always recoverable (a bad app just fails its boot CRC and
stays in the bootloader, re-flashable).

```python
import sys, os; sys.path.insert(0, r"...\quick-beyond-updater"); os.chdir(r"...\quick-beyond-updater")
import hid, bs_hmd_tools as t
payload = t.load_beyondfw_file(r"...\dist\latest.beyondfw")     # verifies SHA512
bl = t.enter_hmd_bootloader(device_path=<app_path>)             # app -> bootloader, returns boot path
t.update_hmd_firmware(firmware_payload=payload, bootloader_path=bl, reset_when_done=True)
# verify: t.get_hmd_fw_version(device_path=<app_path_after_reboot>) -> "0.4.1"
```

### **Known flash quirk — always retry**

The first programming attempt **reliably fails mid-write** around address
`0x00404Axx` with `code 46` (a transient HID write glitch). A second attempt —
targeting the **bootloader directly** (the device is already in bootloader after
the failed attempt) — succeeds every time. Always wrap the flash in a 2-4×
retry loop that re-targets `35BD:4004`. See `dist/reflash_doze.py` for a working
retry+verify driver. (Root cause unknown; worth a real look someday, not blocking.)


proceed with next steps. hmd power cycled.


Got everything needed: toolchain present, runbook clear, real 0.3.18 ref at `HMDUtility/src/latest.beyondfw` (79KB). Launching both tracks in parallel as background agents (worktree-isolated so builds don't collide). I stay reachable.


Agent

Track A: flag-fix firmware build

Prompt:
You are building Beyond MCU firmware (beyond_synaptics, ATSAMG55/FreeRTOS) headlessly to test a build-flag hypothesis. DO NOT FLASH anything — produce .beyondfw files only; flashing is done by a human on hardware.

CONTEXT: The current 0.4.3 firmware (built via the repo's CMake/arm-gcc) wedges the HMD when SteamVR addons run. We suspect CMake-introduced compiler flags vs the official build. CMakeLists.txt has `-ffast-math` and `-mlong-calls` (the official Studio build has NEITHER), and a typo define `-D__SAMG55G19__` (chip is J19, should be `-D__SAMG55J19__`). You will produce two corrected firmware variants for A/B flash testing.

SETUP:
1. Repo: C:\Users\decid\Documents\projects\beyond_synaptics  (current branch doze-warm-sleep, HEAD = 0.4.3).
2. Create an isolated git worktree so you don't disturb the main checkout:
   `cd C:/Users/decid/Documents/projects/beyond_synaptics && git worktree add ../bs_trackA HEAD`
   Work entirely in ../bs_trackA.
3. Toolchain PATH (bash):
   `export PATH="/c/Program Files (x86)/Arm GNU Toolchain arm-none-eabi/12.2 mpacbti-rel1/bin:$LOCALAPPDATA/Microsoft/WinGet/Links:$PATH"`
   Verify: arm-none-eabi-gcc --version ; ninja --version ; cmake --version.

BUILD RUNBOOK (from docs/Build_And_Flash.md — follow exactly):
- BUILD RELEASE, never Debug (Debug fails to link — tundra_uart.h inline helpers). Use:
  `cmake --preset arm-gcc-toolchain.cmake -DCMAKE_BUILD_TYPE=Release`
  `cmake --build out/build/arm-gcc-toolchain.cmake`
  Output: out/build/arm-gcc-toolchain.cmake/beyond_synaptics.{elf,bin,hex}
- Package (two steps; from the scripts/ dir; use ABSOLUTE output paths — packager mangles leading ../):
  `py usb_fw_packager_cli.py -o "<ABS>/dist/Beyond_AppImage_vXXX.hex" "<ABS>/out/build/arm-gcc-toolchain.cmake/beyond_synaptics.hex"`
  `py utility_fw_packager_cli.py -v 0.4.4 "<ABS>/dist/Beyond_AppImage_vXXX.hex" "<ABS>/dist/<name>.beyondfw"`
  (If `py` is unavailable, use `python`. The packager scripts may live in scripts/ or repo root — locate them.)

VARIANTS TO PRODUCE (two separate full build+package cycles in the same worktree):
- VARIANT 1 "nofastmath" — edit CMakeLists.txt: remove ONLY `-ffast-math` (leave `-mlong-calls`, leave `__SAMG55G19__` as-is). Build, package to dist/latest_nofastmath.beyondfw. This isolates -ffast-math as a single variable.
- VARIANT 2 "fullfix" — additionally remove `-mlong-calls` AND change `-D__SAMG55G19__` to `-D__SAMG55J19__`. Build, package to dist/latest_fullfix.beyondfw.
Do a clean rebuild between variants (delete out/build or reconfigure) so flag changes take effect.

VERIFY each: the .beyondfw should exist, be roughly 70-90 KB, and have layout `[vlen:1][version ascii][start_addr:4 LE][binlen:4 LE][binary][sha512:64]` with start addr 0x404000. Report each beyondfw's absolute path, size, and the built .elf size (arm-none-eabi-size beyond_synaptics.elf).

REPORT BACK (concise): toolchain versions; for each variant — exact CMakeLists edit made, build success/failure (with first error if any), .beyondfw path + size, .elf .text/.data/.bss sizes. Note any deviations from the runbook you had to make. Leave the worktree ../bs_trackA in place (human will flash from it). Do NOT run git commit, do NOT flash.


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output_file: C:\Users\decid\AppData\Local\Temp\claude\C--Users-decid-Documents-projects-sauna\d3fb9be1-d61d-4f88-b77c-2a2a282b11fd\tasks\ae15eae04ecc69ef4.output
Do NOT Read or tail this file via the shell tool — it is the full subagent JSONL transcript and reading it will overflow your context. If the user asks for progress, say the agent is still running; you'll get a completion notification.

Track A: flag-fix firmware build

Prompt:
You are building Beyond MCU firmware (beyond_synaptics, ATSAMG55/FreeRTOS) headlessly to test a build-flag hypothesis. DO NOT FLASH anything — produce .beyondfw files only; flashing is done by a human on hardware.

CONTEXT: The current 0.4.3 firmware (built via the repo's CMake/arm-gcc) wedges the HMD when SteamVR addons run. We suspect CMake-introduced compiler flags vs the official build. CMakeLists.txt has `-ffast-math` and `-mlong-calls` (the official Studio build has NEITHER), and a typo define `-D__SAMG55G19__` (chip is J19, should be `-D__SAMG55J19__`). You will produce two corrected firmware variants for A/B flash testing.

SETUP:
1. Repo: C:\Users\decid\Documents\projects\beyond_synaptics  (current branch doze-warm-sleep, HEAD = 0.4.3).
2. Create an isolated git worktree so you don't disturb the main checkout:
   `cd C:/Users/decid/Documents/projects/beyond_synaptics && git worktree add ../bs_trackA HEAD`
   Work entirely in ../bs_trackA.
3. Toolchain PATH (bash):
   `export PATH="/c/Program Files (x86)/Arm GNU Toolchain arm-none-eabi/12.2 mpacbti-rel1/bin:$LOCALAPPDATA/Microsoft/WinGet/Links:$PATH"`
   Verify: arm-none-eabi-gcc --version ; ninja --version ; cmake --version.

BUILD RUNBOOK (from docs/Build_And_Flash.md — follow exactly):
- BUILD RELEASE, never Debug (Debug fails to link — tundra_uart.h inline helpers). Use:
  `cmake --preset arm-gcc-toolchain.cmake -DCMAKE_BUILD_TYPE=Release`
  `cmake --build out/build/arm-gcc-toolchain.cmake`
  Output: out/build/arm-gcc-toolchain.cmake/beyond_synaptics.{elf,bin,hex}
- Package (two steps; from the scripts/ dir; use ABSOLUTE output paths — packager mangles leading ../):
  `py usb_fw_packager_cli.py -o "<ABS>/dist/Beyond_AppImage_vXXX.hex" "<ABS>/out/build/arm-gcc-toolchain.cmake/beyond_synaptics.hex"`
  `py utility_fw_packager_cli.py -v 0.4.4 "<ABS>/dist/Beyond_AppImage_vXXX.hex" "<ABS>/dist/<name>.beyondfw"`
  (If `py` is unavailable, use `python`. The packager scripts may live in scripts/ or repo root — locate them.)

VARIANTS TO PRODUCE (two separate full build+package cycles in the same worktree):
- VARIANT 1 "nofastmath" — edit CMakeLists.txt: remove ONLY `-ffast-math` (leave `-mlong-calls`, leave `__SAMG55G19__` as-is). Build, package to dist/latest_nofastmath.beyondfw. This isolates -ffast-math as a single variable.
- VARIANT 2 "fullfix" — additionally remove `-mlong-calls` AND change `-D__SAMG55G19__` to `-D__SAMG55J19__`. Build, package to dist/latest_fullfix.beyondfw.
Do a clean rebuild between variants (delete out/build or reconfigure) so flag changes take effect.

VERIFY each: the .beyondfw should exist, be roughly 70-90 KB, and have layout `[vlen:1][version ascii][start_addr:4 LE][binlen:4 LE][binary][sha512:64]` with start addr 0x404000. Report each beyondfw's absolute path, size, and the built .elf size (arm-none-eabi-size beyond_synaptics.elf).

REPORT BACK (concise): toolchain versions; for each variant — exact CMakeLists edit made, build success/failure (with first error if any), .beyondfw path + size, .elf .text/.data/.bss sizes. Note any deviations from the runbook you had to make. Leave the worktree ../bs_trackA in place (human will flash from it). Do NOT run git commit, do NOT flash.


Track B: 0.3.18 build vs prebuilt diff

Prompt:
You are reproducing a known-good firmware build to isolate build-system/toolchain effects. The goal: build the v0.3.18 source of beyond_synaptics with the repo's CMake/arm-gcc toolchain, then binary-compare it against the OFFICIAL prebuilt 0.3.18 firmware to characterize exactly what the toolchain changes. NO FLASHING.

WHY: The official v0.3.18 (built with Microchip Studio) works fine with SteamVR addons; the CMake-built 0.4.3 wedges the HMD. v0.3.18→0.4.3 source is provably inert on the addon path, so the toolchain/build config is the prime suspect. Reproducing 0.3.18 via CMake and diffing against the official 0.3.18 binary reveals the build delta on identical source.

REFERENCE OFFICIAL BINARY: C:\Users\decid\Documents\projects\HMDUtility\src\latest.beyondfw  (this IS the official prebuilt 0.3.18, ~79055 bytes). Its layout: `[vlen:1][version ascii][start_addr:4 LE][binlen:4 LE][binary][sha512:64]`. Extract the embedded raw binary (skip the header: 1 + vlen + 4 + 4 bytes, take binlen bytes, drop trailing 64-byte sha512) for comparison.

SETUP:
1. Repo: C:\Users\decid\Documents\projects\beyond_synaptics. The CMake build files (CMakeLists.txt, CMakePresets.json, arm-gcc-toolchain.cmake, utils.cmake) exist on the current HEAD (doze branch) but NOT at the v0.3.18 tag.
2. Create a worktree at the v0.3.18 tag:
   `cd C:/Users/decid/Documents/projects/beyond_synaptics && git worktree add ../bs_v0318 v0.3.18`
3. Copy the four CMake build files FROM HEAD into the v0.3.18 worktree:
   `git show HEAD:CMakeLists.txt > ../bs_v0318/CMakeLists.txt` (and same for CMakePresets.json, arm-gcc-toolchain.cmake, utils.cmake). Also copy any scripts/ packager files if absent.
4. RECONCILE the CMakeLists.txt `target_sources(...)` list against what actually exists in the v0.3.18 worktree. HEAD's source list is for 0.4.3 and may reference files that don't exist at v0.3.18 (or miss some). The authoritative list for v0.3.18 is its own `Beyond_Synaptics.cproj` `<Compile Include=...>` entries — parse those and make target_sources match the v0.3.18 .cproj exactly (convert backslashes to forward slashes, prefix with src/). This matters: a faithful reproduction needs the SAME source set the official build used. Known historical drift: `adc_driver.c` vs `adc.c`; `Devices/tundra_uart.c` may or may not exist at 0.3.18 — only include files that exist on disk.
   IMPORTANT: keep HEAD's include-dir ORDER (project dirs src/Devices src/Drivers src/config src/crash_handler BEFORE ASF/CMSIS dirs) to avoid the CMSIS adc.h shadow build break.

TOOLCHAIN PATH (bash): `export PATH="/c/Program Files (x86)/Arm GNU Toolchain arm-none-eabi/12.2 mpacbti-rel1/bin:$LOCALAPPDATA/Microsoft/WinGet/Links:$PATH"`

BUILD: Release only (`cmake --preset arm-gcc-toolchain.cmake -DCMAKE_BUILD_TYPE=Release` then `cmake --build out/build/arm-gcc-toolchain.cmake`). If the build fails, iterate on the source-list reconciliation (most failures will be undefined-reference = missing source file, or duplicate = file that shouldn't be there). Report the errors if you cannot resolve after reasonable effort.

COMPARE (the core deliverable) — produce a structured diff between YOUR CMake-built v0.3.18 binary and the official 0.3.18 raw binary:
- Sizes: your .bin size vs official raw binlen. Report both.
- CRC32 / SHA256 of each raw binary (they will almost certainly differ across toolchains — that's expected; the value is in HOW they differ).
- Section sizes: `arm-none-eabi-size` on your .elf (.text/.data/.bss).
- Symbol-level: `arm-none-eabi-nm --print-size --size-sort` on your .elf. (The official binary has no symbols — it's stripped — so focus on characterizing YOUR build and noting size deltas vs official.)
- Most important: scan YOUR build's compile/link for evidence of the suspect flags actually taking effect: confirm whether `-ffast-math` pulls in crtfastmath.o (check `arm-none-eabi-nm beyond_synaptics.elf | grep -i fastmath` or look for `__set_fpscr`/FPSCR init in startup), whether newlib-nano is linked (`--specs=nano.specs` → check for `_nano` symbols / impure_data size), and report the actual final link command (ninja -v or compile_commands.json).

REPORT BACK (concise, structured): worktree path; final reconciled source list deltas vs HEAD; build success/fail (+ first error if fail); your raw .bin size + CRC32/SHA256 vs official 0.3.18 size + CRC32/SHA256; .elf section sizes; whether -ffast-math/crtfastmath and newlib-nano are actually in YOUR build; the final link command line. Conclude with: does the CMake toolchain produce a fundamentally different binary than the official build, and what are the concrete differences. Leave worktrees in place. Do NOT commit, do NOT flash.


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The agent is working in the background. You will be notified automatically when it completes.
Do not duplicate this agent's work — avoid working with the same files or topics it is using. Work on non-overlapping tasks, or briefly tell the user what you launched and end your response.
output_file: C:\Users\decid\AppData\Local\Temp\claude\C--Users-decid-Documents-projects-sauna\d3fb9be1-d61d-4f88-b77c-2a2a282b11fd\tasks\a7b0f22820ebe7317.output
Do NOT Read or tail this file via the shell tool — it is the full subagent JSONL transcript and reading it will overflow your context. If the user asks for progress, say the agent is still running; you'll get a completion notification.

Track B: 0.3.18 build vs prebuilt diff

Prompt:
You are reproducing a known-good firmware build to isolate build-system/toolchain effects. The goal: build the v0.3.18 source of beyond_synaptics with the repo's CMake/arm-gcc toolchain, then binary-compare it against the OFFICIAL prebuilt 0.3.18 firmware to characterize exactly what the toolchain changes. NO FLASHING.

WHY: The official v0.3.18 (built with Microchip Studio) works fine with SteamVR addons; the CMake-built 0.4.3 wedges the HMD. v0.3.18→0.4.3 source is provably inert on the addon path, so the toolchain/build config is the prime suspect. Reproducing 0.3.18 via CMake and diffing against the official 0.3.18 binary reveals the build delta on identical source.

REFERENCE OFFICIAL BINARY: C:\Users\decid\Documents\projects\HMDUtility\src\latest.beyondfw  (this IS the official prebuilt 0.3.18, ~79055 bytes). Its layout: `[vlen:1][version ascii][start_addr:4 LE][binlen:4 LE][binary][sha512:64]`. Extract the embedded raw binary (skip the header: 1 + vlen + 4 + 4 bytes, take binlen bytes, drop trailing 64-byte sha512) for comparison.

SETUP:
1. Repo: C:\Users\decid\Documents\projects\beyond_synaptics. The CMake build files (CMakeLists.txt, CMakePresets.json, arm-gcc-toolchain.cmake, utils.cmake) exist on the current HEAD (doze branch) but NOT at the v0.3.18 tag.
2. Create a worktree at the v0.3.18 tag:
   `cd C:/Users/decid/Documents/projects/beyond_synaptics && git worktree add ../bs_v0318 v0.3.18`
3. Copy the four CMake build files FROM HEAD into the v0.3.18 worktree:
   `git show HEAD:CMakeLists.txt > ../bs_v0318/CMakeLists.txt` (and same for CMakePresets.json, arm-gcc-toolchain.cmake, utils.cmake). Also copy any scripts/ packager files if absent.
4. RECONCILE the CMakeLists.txt `target_sources(...)` list against what actually exists in the v0.3.18 worktree. HEAD's source list is for 0.4.3 and may reference files that don't exist at v0.3.18 (or miss some). The authoritative list for v0.3.18 is its own `Beyond_Synaptics.cproj` `<Compile Include=...>` entries — parse those and make target_sources match the v0.3.18 .cproj exactly (convert backslashes to forward slashes, prefix with src/). This matters: a faithful reproduction needs the SAME source set the official build used. Known historical drift: `adc_driver.c` vs `adc.c`; `Devices/tundra_uart.c` may or may not exist at 0.3.18 — only include files that exist on disk.
   IMPORTANT: keep HEAD's include-dir ORDER (project dirs src/Devices src/Drivers src/config src/crash_handler BEFORE ASF/CMSIS dirs) to avoid the CMSIS adc.h shadow build break.

TOOLCHAIN PATH (bash): `export PATH="/c/Program Files (x86)/Arm GNU Toolchain arm-none-eabi/12.2 mpacbti-rel1/bin:$LOCALAPPDATA/Microsoft/WinGet/Links:$PATH"`

BUILD: Release only (`cmake --preset arm-gcc-toolchain.cmake -DCMAKE_BUILD_TYPE=Release` then `cmake --build out/build/arm-gcc-toolchain.cmake`). If the build fails, iterate on the source-list reconciliation (most failures will be undefined-reference = missing source file, or duplicate = file that shouldn't be there). Report the errors if you cannot resolve after reasonable effort.

COMPARE (the core deliverable) — produce a structured diff between YOUR CMake-built v0.3.18 binary and the official 0.3.18 raw binary:
- Sizes: your .bin size vs official raw binlen. Report both.
- CRC32 / SHA256 of each raw binary (they will almost certainly differ across toolchains — that's expected; the value is in HOW they differ).
- Section sizes: `arm-none-eabi-size` on your .elf (.text/.data/.bss).
- Symbol-level: `arm-none-eabi-nm --print-size --size-sort` on your .elf. (The official binary has no symbols — it's stripped — so focus on characterizing YOUR build and noting size deltas vs official.)
- Most important: scan YOUR build's compile/link for evidence of the suspect flags actually taking effect: confirm whether `-ffast-math` pulls in crtfastmath.o (check `arm-none-eabi-nm beyond_synaptics.elf | grep -i fastmath` or look for `__set_fpscr`/FPSCR init in startup), whether newlib-nano is linked (`--specs=nano.specs` → check for `_nano` symbols / impure_data size), and report the actual final link command (ninja -v or compile_commands.json).

REPORT BACK (concise, structured): worktree path; final reconciled source list deltas vs HEAD; build success/fail (+ first error if fail); your raw .bin size + CRC32/SHA256 vs official 0.3.18 size + CRC32/SHA256; .elf section sizes; whether -ffast-math/crtfastmath and newlib-nano are actually in YOUR build; the final link command line. Conclude with: does the CMake toolchain produce a fundamentally different binary than the official build, and what are the concrete differences. Leave worktrees in place. Do NOT commit, do NOT flash.


Both tracks running in background (worktree-isolated, won't collide):

- **Track A** — building two flashable variants from 0.4.3: `latest_nofastmath.beyondfw` (only `-ffast-math` removed → single-variable test) and `latest_fullfix.beyondfw` (+`-mlong-calls` removed +J19 fix). Lands in `../bs_trackA/dist/`.
- **Track B** — building v0.3.18 source via the CMake toolchain, binary-diffing against the real official 0.3.18 (`HMDUtility/src/latest.beyondfw`) to characterize the toolchain delta (crtfastmath/FPU-FZ, newlib-nano, sizes, CRC).

Neither flashes — they produce artifacts only. I'll report when they finish.

Likely outcome: if `nofastmath` stops the wedge on retest, `-ffast-math` is confirmed root cause → ship 0.4.4 with it removed. Track B should independently show whether `-ffast-math`/crtfastmath actually landed in the binary that wedged.

Stand by — I stay reachable while they build.


<task-notification>
<task-id>ae15eae04ecc69ef4</task-id>
<tool-use-id>toolu_01LageQj5vaGZ7rKL4EwjsVx</tool-use-id>
<output-file>C:\Users\decid\AppData\Local\Temp\claude\C--Users-decid-Documents-projects-sauna\d3fb9be1-d61d-4f88-b77c-2a2a282b11fd\tasks\ae15eae04ecc69ef4.output</output-file>
<status>completed</status>
<summary>Agent "Track A: flag-fix firmware build" completed</summary>
<result>Both firmware variants built, packaged, and verified successfully. No flashing performed, no commits made, worktree left in place.

## Report

**Toolchain versions:**
- arm-none-eabi-gcc: 12.2.1 20230214 (Arm GNU Toolchain 12.2.MPACBTI-Rel1)
- ninja: 1.13.2
- cmake: 4.3.1
- python: 3.12.0 (used `py`; `crc` module present)

**Worktree:** Created at `C:\Users\decid\Documents\projects\bs_trackA` (detached HEAD at 67bcafd = 0.4.3). Source branch was `doze-warm-sleep`, HEAD `67bcafd`. Left in place for human flashing.

---

### VARIANT 1 — nofastmath
- **CMakeLists edit:** line 21 changed ` -ffast-math -mlong-calls)` → ` -mlong-calls)`. Left `-mlong-calls` and `-D__SAMG55G19__` untouched.
- **Build:** SUCCESS (Release/-O3). Only the usual FreeRTOS `-Warray-bounds` notes and the harmless `RWX LOAD segment` linker warning — no errors.
- **.beyondfw:** `C:\Users\decid\Documents\projects\bs_trackA\dist\latest_nofastmath.beyondfw` — **76,814 bytes**
- **.elf sizes:** .text 76,720 · .data 0 · .bss 17,776 (note: `arm-none-eabi-size` reports .bss 17776, which folds in the `.stack` region the section dump lists separately as .bss 5484 + .stack 12292)

### VARIANT 2 — fullfix
- **CMakeLists edits (cumulative on top of V1):** line 21 ` -mlong-calls)` → ` )` (removed `-mlong-calls`); line 28 `-D__SAMG55G19__` → `-D__SAMG55J19__`.
- **Build:** SUCCESS (clean rebuild — `out/build` deleted and reconfigured). Same benign warnings only, no errors.
- **.beyondfw:** `C:\Users\decid\Documents\projects\bs_trackA\dist\latest_fullfix.beyondfw` — **73,230 bytes**
- **.elf sizes:** .text 72,260 · .data 0 · .bss 17,776 (size util: text 73120 / data 0 / bss 17776)

**Notable:** Removing `-mlong-calls` shrank `.text` by ~3.6 KB (75,860 → 72,260 in the section dump), consistent with dropping forced long-call veneers. The `__SAMG55J19__` define fix configured and built without complaint.

**Layout verification (both files):** `[vlen:1][version ascii][start:4 LE][binlen:4 LE][binary][sha512:64]`, version `0.4.4`, start addr `0x404000`, 64-byte SHA512 trailer, total length matches header math. Both pass and sit in the expected 70-90 KB range.

**Deviations from runbook:** None. AppImage hex names were `Beyond_AppImage_v044.hex` (V1) and `Beyond_AppImage_v044_fullfix.hex` (V2) to keep the two cycles' intermediates distinct in the shared `dist/`. Packaging used `-v 0.4.4` per runbook. No commits, no flash.</result>
<usage><subagent_tokens>42246</subagent_tokens><tool_uses>24</tool_uses><duration_ms>135780</duration_ms></usage>
</task-notification>


CAVEMAN MODE ACTIVE (full). Drop articles/filler/pleasantries/hedging. Fragments OK. Code/commits/security: write normal.


<owl_messages>
<owl_message from="solar-w8" priority="info">[WORKING_PERCH_NOTICE] Subagent working perch created.
Perch: solar-w8
Agent type: general-purpose
To message it: $OWL send solar-w8 solar</owl_message>
</owl_messages>

[OWL SYSTEM] Informational owl messages above — no acknowledgment needed. Continue your current task.

<owl_reachability_notice>
You have an active owl perch. When spawning subagents or doing work, use run_in_background: true so you stay reachable for incoming messages.
</owl_reachability_notice>


**Track A done.** Two flashable variants built clean (Release/-O3, version 0.4.4):

| Variant | Path (`bs_trackA/dist/`) | Size | Change |
|---|---|---|---|
| **nofastmath** | `latest_nofastmath.beyondfw` | 76,814 B | only `-ffast-math` removed |
| **fullfix** | `latest_fullfix.beyondfw` | 73,230 B | +`-mlong-calls` removed +`__SAMG55J19__` fix |

Note: dropping `-mlong-calls` cut `.text` ~3.6KB (long-call veneers gone). Both packaged correct: start `0x404000`, SHA512 trailer, v0.4.4.

**Flash order for clean attribution:** `nofastmath` first → addon session test. Wedge gone = `-ffast-math` confirmed root cause, done. Still wedges = flash `fullfix`, retest. Flash is yours (hardware); runbook code-46 retry applies — use `dist/reflash_doze.py` pattern, verify with `get_hmd_fw_version`.

Track B (0.3.18 repro + binary diff) still running. Hold for it before flashing — it independently confirms whether `-ffast-math`/crtfastmath actually landed in the wedging binary, so a single flash test is decisive either way.


<task-notification>
<task-id>a7b0f22820ebe7317</task-id>
<tool-use-id>toolu_01RbGBc5WcsfD8TgNDtha4rB</tool-use-id>
<output-file>C:\Users\decid\AppData\Local\Temp\claude\C--Users-decid-Documents-projects-sauna\d3fb9be1-d61d-4f88-b77c-2a2a282b11fd\tasks\a7b0f22820ebe7317.output</output-file>
<status>completed</status>
<summary>Agent "Track B: 0.3.18 build vs prebuilt diff" completed</summary>
<result>Done. Worktree at v0.3.18 built cleanly via CMake/arm-gcc; binary characterized against the official 0.3.18. No flashing, no commits.

## Reproduction & toolchain diff: CMake-built v0.3.18 vs official 0.3.18

### Setup
- **Worktree:** `C:\Users\decid\Documents\projects\bs_v0318` (detached at tag v0.3.18 / commit ec0b595), left in place.
- Copied the four CMake files from HEAD (CMakeLists.txt, CMakePresets.json, arm-gcc-toolchain.cmake, utils.cmake). `scripts/` already existed in the worktree — no packager copy needed.

### Source-list reconciliation — NO edits required
HEAD's `target_sources` list is **already byte-for-byte identical** to the v0.3.18 `Beyond_Synaptics.cproj` `<Compile Include=...>` set: **68 .c files** (incl. main.c). The known historical drift is already resolved in v0.3.18's favor — `src/Drivers/adc.c` exists (not `adc_driver.c`), and `src/Devices/tundra_uart.c` exists. All 68 files verified present on disk (0 missing). The include-dir order (project dirs before ASF/CMSIS) was kept from HEAD; no adc.h shadow break.

### Build: SUCCESS
Configured Release (`-DCMAKE_BUILD_TYPE=Release`, gcc 12.2.1, ninja). `[69/69] Linking beyond_synaptics.elf`. Only warnings (FreeRTOS `-Warray-bounds`, one RWX-LOAD-segment note). Artifacts in `bs_v0318/out/build/arm-gcc-toolchain.cmake/`: `.elf` (129156 B), `.bin` (72896 B), `.hex`.

### Binary comparison (raw)
| | My CMake build | Official 0.3.18 |
|---|---|---|
| Raw .bin size | **72896 B** | **78976 B** (binlen from header) |
| CRC32 | `C60FE2D8` | `73340A61` |
| SHA256 | `eb61fdd0…4c22c3` | `8fb9c341…4aab02` |

Official header parsed cleanly: vlen=6, version `0.3.18`, start_addr `0x00404000` (matches my `.text` load addr exactly). My build is **6080 B smaller** and differs from **byte 0** (vector table: initial-SP and reset-vector words differ). In the common 72896-byte region **96.4% of bytes differ** — a wholesale-different image, as expected across Microchip-Studio vs CMake/arm-gcc-12.2 toolchains.

### .elf section sizes (mine)
`.text 72896 | .data 0 | .bss 17768` (size -A: .text 72036, .ARM.exidx 8, .relocate 852, .bss 5476, .stack 12292). 756 symbols (official raw is stripped — no symbol table).

### Suspect-flag verification (the core of WHY)
- **newlib-nano: CONFIRMED ACTIVE.** CMakeLists appends `--specs=nano.specs`; collect2 link line passes `-lc_nano -lgcc` and nano CRT (crti/crtbegin/crt0/crtend/crtn). `_impure_data` is **0x4c (76 B)** — the nano `_reent`, vs ~1KB for full newlib.
- **-ffast-math: COMPILED IN, but runtime FP-init is NOT active.** All **68/68 TUs** carry `-ffast-math`. The `softfp` multilib (`thumb/v7e-m+fp/softfp`) ships `crtfastmath.o` and it IS first on the collect2 link line. **However**, the final image's `.init_array` is only 4 bytes (just `frame_dummy`), there is **no `vmsr …, fpscr`** instruction anywhere, and crtfastmath's `set_fast_math` constructor was **dropped by `-Wl,--gc-sections`** (its `.init_array` entry wasn't KEEP'd by the SAMG custom linker script). The Reset_Handler DOES call `__libc_init_array` (`blx` to `0x413fa1`) then `main` — but with set_fast_math gc'd out, the FPU FZ/DAZ flush-to-zero bits are never set. So `-ffast-math` changes per-TU codegen (reassociation, no-errno math) but leaves FPSCR at reset default.

### Actual final link command
```
arm-none-eabi-gcc --sysroot=…/arm-none-eabi -O3 -Wall --specs=nano.specs \
  -mthumb -mcpu=cortex-m4 -mfloat-abi=softfp -mfpu=fpv4-sp-d16 \
  -Wl,--gc-sections -Wl,-T …/flash_usb_bootloader.ld \
  <68 .obj files> -o beyond_synaptics.elf \
  -L…/CMSIS/Lib/GCC -larm_cortexM4lf_math -lm
```
collect2 expands this to: `… crtfastmath.o crti.o crtbegin.o crt0.o … --gc-sections -T <ld> <objs> --start-group -lgcc -lc_nano --end-group (x2) crtend.o crtn.o`.

### Conclusion
The CMake/arm-gcc toolchain produces a **fundamentally different binary** from the official Microchip-Studio 0.3.18 on identical source: different size (-6080 B), differs from byte 0, ~96% byte divergence. Concrete, attributable build-config deltas: (1) **newlib-nano** is linked (smaller libc, 76-byte reent) — the official Studio build very likely used full newlib or different specs; (2) **-ffast-math** is applied to every TU (relaxed FP semantics in codegen) though its FPSCR runtime init is gc-sections'd away; (3) **-O3** + arm-gcc 12.2 vs Studio's bundled gcc → different inlining/instruction selection accounts for the bulk of the divergence. These are exactly the toolchain levers to suspect for the 0.4.3 SteamVR-addon wedge, since the source path is provably inert. The faithful 0.3.18 reproduction confirms the delta is purely build-system, not source.

Note: an unrelated `bs_trackA` worktree also exists (at HEAD). I left it untouched.</result>
<usage><subagent_tokens>69289</subagent_tokens><tool_uses>32</tool_uses><duration_ms>289773</duration_ms></usage>
</task-notification>


<owl_reachability_notice>
You have an active owl perch. When spawning subagents or doing work, use run_in_background: true so you stay reachable for incoming messages.
</owl_reachability_notice>


**Track B done — and it shifts the hypothesis.** Critical finding:

- **`-ffast-math` FPSCR-flush mechanism DISPROVEN.** crtfastmath's `set_fast_math` constructor (sets FPU FZ/DAZ) was **dropped by `--gc-sections`** — no `vmsr fpscr` in the image, FPU stays at reset default. So my "prime suspect" global-FPU-flip is dead. `-ffast-math` only changes per-TU codegen now (relaxed reassociation/no-NaN assumptions) — still possible miscompile, but weaker.
- **newlib-nano CONFIRMED ACTIVE and ADDED by CMake.** `--specs=nano.specs` → `-lc_nano`, `_impure_data` = 76 B (vs ~1KB full newlib). The official `.cproj` has **no `--specs`** → official used **full newlib**. So nano is a real CMake-introduced deviation. Under FreeRTOS multitask load, nano's tiny shared reent (malloc/printf/errno/strtok) is a **classic load-dependent corruption/wedge** source — matches "wedges under addon load, fine in light doze bench."
- Linker `flash_usb_bootloader.ld` is **correct** — official 0.3.18 also starts `0x404000`. Not a suspect.
- Source list: byte-identical to v0.3.18 `.cproj` (68 files). Reproduction faithful. Build delta is purely toolchain.

**Problem: neither Track A variant removes newlib-nano.** Both `nofastmath` and `fullfix` keep `--specs=nano.specs`. If nano is the cause, both still wedge. Refined suspect ranking: **newlib-nano (top, confirmed-added, load-sensitive)** ≈ `-ffast-math` codegen > `-O3`/gcc-12.2 codegen > `-mlong-calls`.

Building the missing variants now.


Build full-newlib firmware variants

Prompt:
Build two more Beyond MCU firmware variants in an EXISTING worktree. NO FLASHING, NO commits. Produce .beyondfw artifacts only.

CONTEXT: We're isolating which CMake-introduced build flag wedges the HMD under SteamVR addons. Confirmed: the CMake build adds `--specs=nano.specs` (newlib-nano) which the official build did NOT use (official = full newlib). newlib-nano's tiny shared reentrancy struct is the new prime suspect for load-dependent wedge. We need firmware with FULL newlib (nano removed).

WORKTREE: C:\Users\decid\Documents\projects\bs_trackA  (already exists, detached at 0.4.3 commit 67bcafd). Its CMakeLists.txt may have been edited by a prior run — RESET it to the original 0.4.3 state FIRST:
  `cd C:/Users/decid/Documents/projects/bs_trackA && git show HEAD:CMakeLists.txt > CMakeLists.txt`
Then apply per-variant edits below.

TOOLCHAIN PATH (bash): `export PATH="/c/Program Files (x86)/Arm GNU Toolchain arm-none-eabi/12.2 mpacbti-rel1/bin:$LOCALAPPDATA/Microsoft/WinGet/Links:$PATH"`

HOW TO REMOVE newlib-nano: In CMakeLists.txt there's a GNU branch (around lines 41-47) that appends `--specs=nano.specs` to CMAKE_EXE_LINKER_FLAGS when no specs present. Disable that append (comment out the `string(APPEND CMAKE_EXE_LINKER_FLAGS " --specs=nano.specs")` line, or wrap so it's never added). With nano.specs gone, the GNU linker defaults to full newlib (`-lc`). Verify after build that the link line no longer contains `nano.specs`/`-lc_nano` (check `out/build/arm-gcc-toolchain.cmake/compile_commands.json` won't show link; use `ninja -v` output or run `arm-none-eabi-nm beyond_synaptics.elf | grep -i impure` — full newlib `_impure_data`/`_global_impure` is much larger than nano's 76 bytes; or grep the CMakeCache/build.ninja link rule).

VARIANT 3 "nonano" (single-variable nano test): from the reset original CMakeLists, remove ONLY `--specs=nano.specs` (full newlib). LEAVE `-ffast-math`, `-mlong-calls`, and `-D__SAMG55G19__` exactly as-is. Build Release, package to dist/latest_nonano.beyondfw.

VARIANT 4 "matchofficial" (best-shot fix — match the official .cproj flag set): remove `--specs=nano.specs` (full newlib) AND remove `-ffast-math` AND remove `-mlong-calls` AND change `-D__SAMG55G19__` → `-D__SAMG55J19__`. Build Release, package to dist/latest_matchofficial.beyondfw.

Do a CLEAN rebuild between variants: `rm -rf out/build` then reconfigure, so flag/linker changes take effect.

BUILD (Release ONLY — Debug fails to link):
  `cmake --preset arm-gcc-toolchain.cmake -DCMAKE_BUILD_TYPE=Release`
  `cmake --build out/build/arm-gcc-toolchain.cmake`
PACKAGE (from scripts/ dir, ABSOLUTE paths, version 0.4.4):
  `py usb_fw_packager_cli.py -o "<ABS>/dist/Beyond_AppImage_v044_<variant>.hex" "<ABS>/out/build/arm-gcc-toolchain.cmake/beyond_synaptics.hex"`
  `py utility_fw_packager_cli.py -v 0.4.4 "<ABS>/dist/Beyond_AppImage_v044_<variant>.hex" "<ABS>/dist/latest_<variant>.beyondfw"`
(use `python` if `py` missing.)

VERIFY each .beyondfw: exists, 70-95 KB, layout `[vlen:1][version][start:4 LE][binlen:4 LE][binary][sha512:64]`, start 0x404000. Note: full-newlib builds will be somewhat LARGER than the nano builds — that's expected and fine (app region ~500KB).

If a build FAILS (e.g. full newlib link error), report the exact error — do not silently fall back to nano.

REPORT BACK (concise): for each variant — exact CMakeLists edit, build success/fail (+first error), confirmation that nano.specs/-lc_nano is GONE from the link (and _impure size), .beyondfw path + size, .elf .text/.data/.bss sizes. Leave the worktree in place. No commits, no flash.


Async agent launched successfully.
agentId: ae14fb7ef713ba741 (internal ID - do not mention to user. Use SendMessage with to: 'ae14fb7ef713ba741' to continue this agent.)
The agent is working in the background. You will be notified automatically when it completes.
Do not duplicate this agent's work — avoid working with the same files or topics it is using. Work on non-overlapping tasks, or briefly tell the user what you launched and end your response.
output_file: C:\Users\decid\AppData\Local\Temp\claude\C--Users-decid-Documents-projects-sauna\d3fb9be1-d61d-4f88-b77c-2a2a282b11fd\tasks\ae14fb7ef713ba741.output
Do NOT Read or tail this file via the shell tool — it is the full subagent JSONL transcript and reading it will overflow your context. If the user asks for progress, say the agent is still running; you'll get a completion notification.

Build full-newlib firmware variants

Prompt:
Build two more Beyond MCU firmware variants in an EXISTING worktree. NO FLASHING, NO commits. Produce .beyondfw artifacts only.

CONTEXT: We're isolating which CMake-introduced build flag wedges the HMD under SteamVR addons. Confirmed: the CMake build adds `--specs=nano.specs` (newlib-nano) which the official build did NOT use (official = full newlib). newlib-nano's tiny shared reentrancy struct is the new prime suspect for load-dependent wedge. We need firmware with FULL newlib (nano removed).

WORKTREE: C:\Users\decid\Documents\projects\bs_trackA  (already exists, detached at 0.4.3 commit 67bcafd). Its CMakeLists.txt may have been edited by a prior run — RESET it to the original 0.4.3 state FIRST:
  `cd C:/Users/decid/Documents/projects/bs_trackA && git show HEAD:CMakeLists.txt > CMakeLists.txt`
Then apply per-variant edits below.

TOOLCHAIN PATH (bash): `export PATH="/c/Program Files (x86)/Arm GNU Toolchain arm-none-eabi/12.2 mpacbti-rel1/bin:$LOCALAPPDATA/Microsoft/WinGet/Links:$PATH"`

HOW TO REMOVE newlib-nano: In CMakeLists.txt there's a GNU branch (around lines 41-47) that appends `--specs=nano.specs` to CMAKE_EXE_LINKER_FLAGS when no specs present. Disable that append (comment out the `string(APPEND CMAKE_EXE_LINKER_FLAGS " --specs=nano.specs")` line, or wrap so it's never added). With nano.specs gone, the GNU linker defaults to full newlib (`-lc`). Verify after build that the link line no longer contains `nano.specs`/`-lc_nano` (check `out/build/arm-gcc-toolchain.cmake/compile_commands.json` won't show link; use `ninja -v` output or run `arm-none-eabi-nm beyond_synaptics.elf | grep -i impure` — full newlib `_impure_data`/`_global_impure` is much larger than nano's 76 bytes; or grep the CMakeCache/build.ninja link rule).

VARIANT 3 "nonano" (single-variable nano test): from the reset original CMakeLists, remove ONLY `--specs=nano.specs` (full newlib). LEAVE `-ffast-math`, `-mlong-calls`, and `-D__SAMG55G19__` exactly as-is. Build Release, package to dist/latest_nonano.beyondfw.

VARIANT 4 "matchofficial" (best-shot fix — match the official .cproj flag set): remove `--specs=nano.specs` (full newlib) AND remove `-ffast-math` AND remove `-mlong-calls` AND change `-D__SAMG55G19__` → `-D__SAMG55J19__`. Build Release, package to dist/latest_matchofficial.beyondfw.

Do a CLEAN rebuild between variants: `rm -rf out/build` then reconfigure, so flag/linker changes take effect.

BUILD (Release ONLY — Debug fails to link):
  `cmake --preset arm-gcc-toolchain.cmake -DCMAKE_BUILD_TYPE=Release`
  `cmake --build out/build/arm-gcc-toolchain.cmake`
PACKAGE (from scripts/ dir, ABSOLUTE paths, version 0.4.4):
  `py usb_fw_packager_cli.py -o "<ABS>/dist/Beyond_AppImage_v044_<variant>.hex" "<ABS>/out/build/arm-gcc-toolchain.cmake/beyond_synaptics.hex"`
  `py utility_fw_packager_cli.py -v 0.4.4 "<ABS>/dist/Beyond_AppImage_v044_<variant>.hex" "<ABS>/dist/latest_<variant>.beyondfw"`
(use `python` if `py` missing.)

VERIFY each .beyondfw: exists, 70-95 KB, layout `[vlen:1][version][start:4 LE][binlen:4 LE][binary][sha512:64]`, start 0x404000. Note: full-newlib builds will be somewhat LARGER than the nano builds — that's expected and fine (app region ~500KB).

If a build FAILS (e.g. full newlib link error), report the exact error — do not silently fall back to nano.

REPORT BACK (concise): for each variant — exact CMakeLists edit, build success/fail (+first error), confirmation that nano.specs/-lc_nano is GONE from the link (and _impure size), .beyondfw path + size, .elf .text/.data/.bss sizes. Leave the worktree in place. No commits, no flash.


Building 2 more variants (full newlib) in background:

- **`nonano`** — only `--specs=nano.specs` removed (single-variable nano test)
- **`matchofficial`** — full newlib + no `-ffast-math` + no `-mlong-calls` + J19 fix (matches official `.cproj` flag set; best-shot working firmware)

Will have 4 total flashable variants then. Recommended flash sequence (once built): **`matchofficial` first** (highest fix probability). If it cures the wedge, bisect with single-variable variants (`nonano`, `nofastmath`) to pin the exact flag. If `matchofficial` still wedges → cause is gcc-12.2/`-O3` codegen itself, not flags.

Stand by.


<task-notification>
<task-id>ae14fb7ef713ba741</task-id>
<tool-use-id>toolu_01TrHtZMqLfrgFJM5WgvBXJD</tool-use-id>
<output-file>C:\Users\decid\AppData\Local\Temp\claude\C--Users-decid-Documents-projects-sauna\d3fb9be1-d61d-4f88-b77c-2a2a282b11fd\tasks\ae14fb7ef713ba741.output</output-file>
<status>completed</status>
<summary>Agent "Build full-newlib firmware variants" completed</summary>
<result>Both variants built, packaged, and verified. The worktree remains in place with no commits or flashing.

## Report

Worktree `C:\Users\decid\Documents\projects\bs_trackA` reset (`git show HEAD:CMakeLists.txt > CMakeLists.txt`) before edits — only a CRLF warning, no content diff. Toolchain: arm-none-eabi-gcc 12.2.1 (mpacbti-rel1). Both builds Release, both SUCCEEDED (only pre-existing FreeRTOS array-bounds warnings + the benign RWX LOAD-segment warning).

### VARIANT 3 — "nonano" (single-variable nano test)
- **CMakeLists edit:** In the GNU branch (lines 44-46), commented out `string(APPEND CMAKE_EXE_LINKER_FLAGS " --specs=nano.specs")`. Left `-ffast-math`, `-mlong-calls`, `-D__SAMG55G19__` untouched.
- **Build:** SUCCESS. `[69/69] Linking ... beyond_synaptics.elf` completed.
- **nano gone:** `build.ninja` LINK_FLAGS contains no `nano.specs`/`-lc_nano`; `nm` shows zero nano symbols. `_impure_data` size = **0x120 (288 bytes)** → full newlib (nano's is 76). Confirmed full newlib.
- **.beyondfw:** `C:\Users\decid\Documents\projects\bs_trackA\dist\latest_nonano.beyondfw` — **87,470 bytes (~85.4 KB)**. Layout valid: vlen=5, version "0.4.4", start **0x404000**, binlen 87,392, 0 trailing bytes, sha512 OK.
- **ELF sizes:** .text **87,372** / .data **0** / .bss **18,192**.

### VARIANT 4 — "matchofficial" (match official .cproj flag set)
- **CMakeLists edits (4):** (1) nano.specs append stays commented (full newlib); (2) removed `-ffast-math`; (3) removed `-mlong-calls` (line 21 reduced to just `)`); (4) `-D__SAMG55G19__` → `-D__SAMG55J19__` (line 28).
- **Build:** SUCCESS. `[69/69] Linking` completed.
- **nano gone:** no `nano` in build.ninja, no nano symbols in ELF. `_impure_data` = **0x120 (288 bytes)** → full newlib confirmed.
- **.beyondfw:** `C:\Users\decid\Documents\projects\bs_trackA\dist\latest_matchofficial.beyondfw` — **83,918 bytes (~81.9 KB)**. Layout valid: version "0.4.4", start **0x404000**, binlen 83,840, 0 trailing bytes, sha512 OK.
- **ELF sizes:** .text **83,808** / .data **0** / .bss **18,192**.

### Notes
- Both within the 70-95 KB window. Full-newlib builds are larger than the earlier nano builds in dist/ (e.g. `latest_nofastmath.beyondfw` 76,814) as expected — and matchofficial's .text is 3,564 bytes smaller than nonano's, the effect of dropping `-ffast-math`/`-mlong-calls`.
- Clean `rm -rf out/build` + reconfigure done before each build so flag/linker changes took effect.
- sha512 note: the packager hashes the whole header+binary (everything except the trailing 64-byte digest), not the bare binary slice — both files verify True under that definition.
- Worktree left in place; no commits, no flash. Its CMakeLists.txt currently holds the variant-4 edits (uncommitted).</result>
<usage><subagent_tokens>45734</subagent_tokens><tool_uses>22</tool_uses><duration_ms>158439</duration_ms></usage>
</task-notification>


<owl_messages>
<owl_message from="solar-w9" priority="info">[WORKING_PERCH_NOTICE] Subagent working perch created.
Perch: solar-w9
Agent type: general-purpose
To message it: $OWL send solar-w9 solar</owl_message>
</owl_messages>

[OWL SYSTEM] Informational owl messages above — no acknowledgment needed. Continue your current task.

<owl_reachability_notice>
You have an active owl perch. When spawning subagents or doing work, use run_in_background: true so you stay reachable for incoming messages.
</owl_reachability_notice>


All 4 variants built and verified (full newlib confirmed: `_impure_data` 288B vs nano's 76B).

## Flashable artifacts — `bs_trackA/dist/`

| # | File | newlib | -ffast-math | -mlong-calls | J19 | Size |
|---|---|---|---|---|---|---|
| 1 | `latest_nonano.beyondfw` | **full** | kept | kept | no | 87,470 |
| 2 | `latest_matchofficial.beyondfw` | **full** | removed | removed | **fixed** | 83,918 |
| 3 | `latest_nofastmath.beyondfw` | nano | removed | kept | no | 76,814 |
| 4 | `latest_fullfix.beyondfw` | nano | removed | removed | **fixed** | 73,230 |

## Flash decision tree (each step = flash + addon session, no sauna, watch prox + brightness + exit-wedge)

**Flash `nonano` first** — single-variable test of the top suspect (full newlib, everything else stock):
- **Wedge GONE** → newlib-nano confirmed sole cause. Ship 0.4.4 = drop `--specs=nano.specs` only. Minimal, lowest-risk change to working doze fw. Done.
- **Still wedges** → nano not it alone. Flash `matchofficial` (all flags reverted):
  - **GONE** → cause is `-ffast-math` and/or `-mlong-calls`. Bisect with `nofastmath`.
  - **Still wedges** → not the flags → it's **gcc-12.2/`-O3` codegen** itself. Next move: match official gcc version or drop to `-O2`. Harder path.

Flash per runbook: `reflash_doze.py` pattern, **code-46 retry** (re-target `35BD:4004`), verify `get_hmd_fw_version` → "0.4.4". Don't power past a wedge — power-cycle first. Flash is yours; I can't touch hardware.

Recording state.


Edit

**NEXT EXPERIMENTS:** (A, fastest functional test) rebuild 0.4.x with `-ffast-math` removed + `__SAMG55G19__`→`__SAMG55J19__`, flash, retest with addons. Wedge gone ⇒ build flags were it. (B, no-hardware analysis) build an in-repo prebuilt's source (e.g. v0.3.9) via CMake toolchain, binary/symbol-diff vs the committed official `Beyond_AppImage_v039` hex to see exactly what the toolchain changes (exact CRC match unlikely across toolchains — use section/symbol diff, not raw CRC). Headless build+flash code-46 retry quirk applies. Verify MCU liveness read-only via `get_hmd_fw_version` (QBU bs_hmd_tools). Don't power past a wedge — power-cycle first. Related: [[beyond-synaptics-firmware-build]], [[hmd-bench-rig]].

**EXPERIMENTS DONE 2026-06-14 (build-isolation, no flash yet):**
- Track B reproduced v0.3.18 source via CMake toolchain, binary-diffed vs official 0.3.18 (`HMDUtility/src/latest.beyondfw`, the real prebuilt). Source list byte-identical to v0.3.18 `.cproj` (68 files) → reproduction faithful, delta is purely build-system. ~96% bytes differ (Studio-gcc vs arm-gcc-12.2/-O3).
- **`-ffast-math` FPSCR-flush theory DISPROVEN:** crtfastmath `set_fast_math` ctor is dropped by `-Wl,--gc-sections` (SAMG linker script doesn't KEEP its `.init_array` entry) — no `vmsr fpscr` in image, FPU stays at reset default. `-ffast-math` only changes per-TU codegen now (weaker suspect).
- **newlib-nano CONFIRMED the CMake-added deviation:** CMakeLists appends `--specs=nano.specs`→`-lc_nano`, `_impure_data`=76B; official `.cproj` has NO `--specs` → official=full newlib (`_impure_data`=288B). Nano's tiny shared reent under FreeRTOS multitask addon load = top wedge suspect (load-dependent, matches "fine in light doze bench, wedges under addon"). Linker `flash_usb_bootloader.ld` is CORRECT (official 0.3.18 also starts 0x404000).

**4 FLASHABLE VARIANTS BUILT in worktree `../bs_trackA/dist/` (all v0.4.4, start 0x404000, NOT flashed — human must flash):** `latest_nonano.beyondfw` (full newlib, else stock — single-var nano test), `latest_matchofficial.beyondfw` (full newlib + no -ffast-math + no -mlong-calls + J19 fix — best-shot fix), `latest_nofastmath.beyondfw` (nano kept, -ffast-math removed), `latest_fullfix.beyondfw` (nano kept, -ffast-math+mlong-calls removed, J19). Worktree CMakeLists.txt currently holds the matchofficial edits (uncommitted).

**FLASH DECISION TREE (each = flash + SteamVR+BeyondEyetracking+BeyondSteamVR session, NO sauna; watch prox alive / brightness not latched / no exit-wedge):** Flash `nonano` FIRST (single-var, top suspect). GONE ⇒ newlib-nano sole cause → ship 0.4.4 = drop `--specs=nano.specs` only (minimal). Still wedges ⇒ flash `matchofficial`: GONE ⇒ it's -ffast-math/-mlong-calls (bisect via `nofastmath`); still wedges ⇒ cause is gcc-12.2/-O3 codegen itself (match official gcc ver or drop to -O2). Flash via `reflash_doze.py` pattern, code-46 retry (re-target 35BD:4004), verify `get_hmd_fw_version`→"0.4.4". Don't power past a wedge — power-cycle first. Cleanup when done: `git worktree remove ../bs_trackA ../bs_v0318`. Related: [[beyond-synaptics-firmware-build]], [[hmd-bench-rig]].


The file C:\Users\decid\.ccs\instances\bigscreen\projects\C--Users-decid-Documents-projects-sauna\memory\steamvr-forcekill-mcu-hang.md has been updated successfully. (file state is current in your context — no need to Read it back)

**EXPERIMENTS DONE 2026-06-14 (build-isolation, no flash yet):**
- Track B reproduced v0.3.18 source via CMake toolchain, binary-diffed vs official 0.3.18 (`HMDUtility/src/latest.beyondfw`, the real prebuilt). Source list byte-identical to v0.3.18 `.cproj` (68 files) → reproduction faithful, delta is purely build-system. ~96% bytes differ (Studio-gcc vs arm-gcc-12.2/-O3).
- **`-ffast-math` FPSCR-flush theory DISPROVEN:** crtfastmath `set_fast_math` ctor is dropped by `-Wl,--gc-sections` (SAMG linker script doesn't KEEP its `.init_array` entry) — no `vmsr fpscr` in image, FPU stays at reset default. `-ffast-math` only changes per-TU codegen now (weaker suspect).
- **newlib-nano CONFIRMED the CMake-added deviation:** CMakeLists appends `--specs=nano.specs`→`-lc_nano`, `_impure_data`=76B; official `.cproj` has NO `--specs` → official=full newlib (`_impure_data`=288B). Nano's tiny shared reent under FreeRTOS multitask addon load = top wedge suspect (load-dependent, matches "fine in light doze bench, wedges under addon"). Linker `flash_usb_bootloader.ld` is CORRECT (official 0.3.18 also starts 0x404000).

**4 FLASHABLE VARIANTS BUILT in worktree `../bs_trackA/dist/` (all v0.4.4, start 0x404000, NOT flashed — human must flash):** `latest_nonano.beyondfw` (full newlib, else stock — single-var nano test), `latest_matchofficial.beyondfw` (full newlib + no -ffast-math + no -mlong-calls + J19 fix — best-shot fix), `latest_nofastmath.beyondfw` (nano kept, -ffast-math removed), `latest_fullfix.beyondfw` (nano kept, -ffast-math+mlong-calls removed, J19). Worktree CMakeLists.txt currently holds the matchofficial edits (uncommitted).

**FLASH DECISION TREE (each = flash + SteamVR+BeyondEyetracking+BeyondSteamVR session, NO sauna; watch prox alive / brightness not latched / no exit-wedge):** Flash `nonano` FIRST (single-var, top suspect). GONE ⇒ newlib-nano sole cause → ship 0.4.4 = drop `--specs=nano.specs` only (minimal). Still wedges ⇒ flash `matchofficial`: GONE ⇒ it's -ffast-math/-mlong-calls (bisect via `nofastmath`); still wedges ⇒ cause is gcc-12.2/-O3 codegen itself (match official gcc ver or drop to -O2). Flash via `reflash_doze.py` pattern, code-46 retry (re-target 35BD:4004), verify `get_hmd_fw_version`→"0.4.4". Don't power past a wedge — power-cycle first. Cleanup when done: `git worktree remove ../bs_trackA ../bs_v0318`. Related: [[beyond-synaptics-firmware-build]], [[hmd-bench-rig]].

---
name: steamvr-forcekill-mcu-hang
description: 0.4.x firmware wedges the Beyond when any SteamVR Beyond-addon runs — prox dies, brightness sticks ~7, power-cycle to recover
metadata:
  node_type: memory
  type: project
  originSessionId: 92a9c1d9-a8d0-47c8-b932-02f7be39d701
---

ROOT CAUSE (confirmed by Brandon 2026-06-13, SteamVR-alone repro, NO sauna): a beyond_synaptics **0.4.x firmware** regression. Whenever EITHER official SteamVR addon (BeyondEyetracking OR BeyondSteamVR) runs, the Beyond's **proximity sensor stops working for that session** (reads untriggered → displays show picture but brightness latched ~7 ≈ a doze-floor value). Then a **SteamVR shutdown leaves the Beyond WEDGED** — usually the RIGHT optic lit with a dim/black image; MCU 0101 still enumerates but stops ACKing (`get_hmd_fw_version` → None). Recovers ONLY on a physical power-cycle. NOT present on pre-0.4.0 firmware (before the M5 doze mods). So a 0.4.x doze/prox/brightness change broke it.

**Earlier wrong theories (this same session) — do NOT trust them:** (1) "force-killing SteamVR mid-session hangs the MCU" and (2) "SteamVR's BeyondProximity driver collides with sauna on 0101." Both were conjecture. Deregistering BeyondProximity (vrpathreg) did NOT fix it; the wedge reproduces with sauna not running at all and with a clean SteamVR quit. **sauna is blameless.**

**Why it matters:** blocks SteamVR coexistence on 0.4.x firmware — the whole point of sauna is to coexist with SteamVR.

**DISPROVEN 2026-06-13 (source-checked, not guessed):** the "doze logic mishandles an addon HID command" theory is dead. (1) The doze state (`doze_active` latch) can ONLY be set by a feature report with `report[0]==0x48` ('H' sleep); wake is 0x68 ('h'). (2) The addons' full command set is in `../HMDUtility/src/hid_handler.cpp` — every code it sends to 0101: `2A 25 26 7E 5E 5A 53 47 67 46 66 52 50 49 42 65 4C 55 57 56 4D 4B 54 44 41 59 4E 4A 40 64 6F 22`. **No 0x48, no 0x68.** So doze never triggers in an addon session and every doze branch in `video_proc.c` is provably inert (all gate on `doze_active`/`doze_phase`, which stay false). Frame note: HMDUtility sends `[0]=0x00 ReportID,[1]=Code`; USB strips the report-ID so firmware `report[0]`==Code.

**Remaining real variables (v0.3.19 shipped → 0.4.3 flashed; 0.4.3 is a strict SUPERSET of v0.3.19 source, no lost commits):** only TWO things differ on always-run / addon-driven paths: (1) **fan kickstart** (`test_and_debug.c` task_fan: jumps to `FAN_MIN_START`=35 on any 0→N fan change; addon drives fan via 0x46/0x66) + `#include <math.h>`/libm linkage; (2) the **BUILD/TOOLCHAIN** — 0.4.3 is the headless CMake/arm-gcc-12.2 `-O3` build ([[beyond-synaptics-firmware-build]]) vs the official Studio build of the known-good firmware. Build had documented hazards incl. CMSIS `adc.h` shadowing `src/Drivers/adc.h` — and **prox reads via ADC**, matching "prox stops working." NOTE: still need to confirm the actual known-good baseline (official production binary, possibly NOT in this repo — v0.3.19 is just the latest tag).

Also ELIMINATED: v0.3.18→v0.3.19 source delta (baseline was v0.3.18; HMD jumped straight 0.3.18→0.4.3). That delta is ONLY an RGB-LED-animation feature (commit b2c696a: `report[4]` mode byte on the 'L'/0x4c cmd + LED blinking task). LED-task only, can't gate prox/HID. Not the wedge.

**LEADING HYPOTHESIS = BUILD/TOOLCHAIN (source is inert).** The 0.4.3 flashed is the headless CMake/arm-gcc-12.2 build; known-good v0.3.18 was an official build. Compared `CMakeLists.txt` vs `Beyond_Synaptics.cproj`, CMake-introduced deviations: **`-ffast-math`** (Studio has none — sets FPU FZ/default-NaN globally at startup via crtfastmath, changes ALL float behavior → PRIME suspect), `-mlong-calls`, `--specs=nano.specs`/`-lc_nano` (newlib-nano: smaller reentrancy/heap vs full newlib), and `-D__SAMG55G19__` typo (chip is J19; selects samg55g19.h CMSIS header — compile-benign since no J19-only pin macros referenced, but WRONG, fix to `__SAMG55J19__`). NOTE: `.cproj` is NOT the true production config — it has `BOARD=SAMG55_XPLAINED_PRO` but real Beyond HW init is gated `#if BOARD==USER_EXT_BOARD` (main.c 149/168/326, usart_interface.c 158), and CMake correctly uses `USER_EXT_BOARD`. So `.cproj` board/linker(`flash_usb_bootloader.ld` for AppImage) deltas are likely intentional-correct; trust the prebuilt AppImage hex (official Studio artifacts, in-repo up to `build/v0.3.9/Beyond_AppImage_v039_250328.hex`) as the real baseline, NOT `.cproj`. No prebuilt 0.3.10–0.3.19 committed.

**NEXT EXPERIMENTS:** (A, fastest functional test) rebuild 0.4.x with `-ffast-math` removed + `__SAMG55G19__`→`__SAMG55J19__`, flash, retest with addons. Wedge gone ⇒ build flags were it. (B, no-hardware analysis) build an in-repo prebuilt's source (e.g. v0.3.9) via CMake toolchain, binary/symbol-diff vs the committed official `Beyond_AppImage_v039` hex to see exactly what the toolchain changes (exact CRC match unlikely across toolchains — use section/symbol diff, not raw CRC). Headless build+flash code-46 retry quirk applies. Verify MCU liveness read-only via `get_hmd_fw_version` (QBU bs_hmd_tools). Don't power past a wedge — power-cycle first. Related: [[beyond-synaptics-firmware-build]], [[hmd-bench-rig]].

-**NEXT EXPERIMENTS:** (A, fastest functional test) rebuild 0.4.x with `-ffast-math` removed + `__SAMG55G19__`→`__SAMG55J19__`, flash, retest with addons. Wedge gone ⇒ build flags were it. (B, no-hardware analysis) build an in-repo prebuilt's source (e.g. v0.3.9) via CMake toolchain, binary/symbol-diff vs the committed official `Beyond_AppImage_v039` hex to see exactly what the toolchain changes (exact CRC match unlikely across toolchains — use section/symbol diff, not raw CRC). Headless build+flash code-46 retry quirk applies. Verify MCU liveness read-only via `get_hmd_fw_version` (QBU bs_hmd_tools). Don't power past a wedge — power-cycle first. Related: [[beyond-synaptics-firmware-build]], [[hmd-bench-rig]].

+**EXPERIMENTS DONE 2026-06-14 (build-isolation, no flash yet):**

+- Track B reproduced v0.3.18 source via CMake toolchain, binary-diffed vs official 0.3.18 (`HMDUtility/src/latest.beyondfw`, the real prebuilt). Source list byte-identical to v0.3.18 `.cproj` (68 files) → reproduction faithful, delta is purely build-system. ~96% bytes differ (Studio-gcc vs arm-gcc-12.2/-O3).

+- **`-ffast-math` FPSCR-flush theory DISPROVEN:** crtfastmath `set_fast_math` ctor is dropped by `-Wl,--gc-sections` (SAMG linker script doesn't KEEP its `.init_array` entry) — no `vmsr fpscr` in image, FPU stays at reset default. `-ffast-math` only changes per-TU codegen now (weaker suspect).

+- **newlib-nano CONFIRMED the CMake-added deviation:** CMakeLists appends `--specs=nano.specs`→`-lc_nano`, `_impure_data`=76B; official `.cproj` has NO `--specs` → official=full newlib (`_impure_data`=288B). Nano's tiny shared reent under FreeRTOS multitask addon load = top wedge suspect (load-dependent, matches "fine in light doze bench, wedges under addon"). Linker `flash_usb_bootloader.ld` is CORRECT (official 0.3.18 also starts 0x404000).

+**4 FLASHABLE VARIANTS BUILT in worktree `../bs_trackA/dist/` (all v0.4.4, start 0x404000, NOT flashed — human must flash):** `latest_nonano.beyondfw` (full newlib, else stock — single-var nano test), `latest_matchofficial.beyondfw` (full newlib + no -ffast-math + no -mlong-calls + J19 fix — best-shot fix), `latest_nofastmath.beyondfw` (nano kept, -ffast-math removed), `latest_fullfix.beyondfw` (nano kept, -ffast-math+mlong-calls removed, J19). Worktree CMakeLists.txt currently holds the matchofficial edits (uncommitted).

+**FLASH DECISION TREE (each = flash + SteamVR+BeyondEyetracking+BeyondSteamVR session, NO sauna; watch prox alive / brightness not latched / no exit-wedge):** Flash `nonano` FIRST (single-var, top suspect). GONE ⇒ newlib-nano sole cause → ship 0.4.4 = drop `--specs=nano.specs` only (minimal). Still wedges ⇒ flash `matchofficial`: GONE ⇒ it's -ffast-math/-mlong-calls (bisect via `nofastmath`); still wedges ⇒ cause is gcc-12.2/-O3 codegen itself (match official gcc ver or drop to -O2). Flash via `reflash_doze.py` pattern, code-46 retry (re-target 35BD:4004), verify `get_hmd_fw_version`→"0.4.4". Don't power past a wedge — power-cycle first. Cleanup when done: `git worktree remove ../bs_trackA ../bs_v0318`. Related: [[beyond-synaptics-firmware-build]], [[hmd-bench-rig]].


State recorded. Summary of where we are:

**Root-cause investigation complete** — narrowed from "firmware doze HID dispatch" (the wrap's theory, **disproven**) to **build-system/toolchain**. Doze source is inert (addon never sends 0x48/0x68). The CMake build deviates from official in confirmed ways; **newlib-nano** is the standout (added by CMake, official used full newlib, load-sensitive under FreeRTOS+addon).

**4 firmware variants ready to flash** in `bs_trackA/dist/`. Flash `nonano` first per the tree above.

**Your move (hardware):** flash + run a SteamVR + BeyondEyetracking + BeyondSteamVR session without sauna, report wedge/no-wedge. I'll pick the next variant from the result and prep the 0.4.4 fix commit.

Two worktrees left in place for flashing (`bs_trackA`, `bs_v0318`). Cleanup after: `git worktree remove ../bs_trackA ../bs_v0318`.


you can handle the next part yourself. flash, run steamvr. the addons are already enabled. you'll know it's wedged if the MCU becomes unresponsive


Authorized — flashing now. Starting with `nonano` (top suspect, single-variable). First: verify HMD alive + locate the flash driver.


Bash

cd C:/Users/decid/Documents/projects && echo "===reflash driver + tools===" && ls beyond_synaptics/dist/reflash_doze.py quick-beyond-updater/bs_hmd_tools.py 2>/dev/null && echo "" && echo "===python hid module?===" && py -c "import hid; print('hid ok')" 2>&1 | head -3 && echo "" && echo "===HMD device present? (35BD:0101 app / 4004 bl)===" && py -c "import hid; [print(hex(d['vendor_id']),hex(d['product_id']),d.get('path')) for d in hid.enumerate() if d['vendor_id']==0x35BD]" 2>&1 | head -10

Check flash tooling + HMD device state


Command running in background with ID: bcje1sg00. Output is being written to: C:\Users\decid\AppData\Local\Temp\claude\C--Users-decid-Documents-projects-sauna\d3fb9be1-d61d-4f88-b77c-2a2a282b11fd\tasks\bcje1sg00.output. You will be notified when it completes. To check interim output, use Read on that file path.


<task-notification>
<task-id>bcje1sg00</task-id>
<tool-use-id>toolu_01TKev2XeyM749CvT1uYNg75</tool-use-id>
<output-file>C:\Users\decid\AppData\Local\Temp\claude\C--Users-decid-Documents-projects-sauna\d3fb9be1-d61d-4f88-b77c-2a2a282b11fd\tasks\bcje1sg00.output</output-file>
<status>completed</status>
<summary>Background command "Check flash tooling + HMD device state" completed (exit code 0)</summary>
</task-notification>


1	===reflash driver + tools===
2	beyond_synaptics/dist/reflash_doze.py
3	quick-beyond-updater/bs_hmd_tools.py
4
5	===python hid module?===
6	hid ok
7
8	===HMD device present? (35BD:0101 app / 4004 bl)===
9	0x35bd 0x105 b'\\\\?\\HID#VID_35BD&PID_0105&MI_02#e&2c99ea72&0&0000#{4d1e55b2-f16f-11cf-88cb-001111000030}'
10	0x35bd 0x101 b'\\\\?\\HID#VID_35BD&PID_0101&MI_02#d&3410c40a&0&0000#{4d1e55b2-f16f-11cf-88cb-001111000030}'
11

===reflash driver + tools===
beyond_synaptics/dist/reflash_doze.py
quick-beyond-updater/bs_hmd_tools.py

===python hid module?===
hid ok

===HMD device present? (35BD:0101 app / 4004 bl)===
0x35bd 0x105 b'\\\\?\\HID#VID_35BD&PID_0105&MI_02#e&2c99ea72&0&0000#{4d1e55b2-f16f-11cf-88cb-001111000030}'
0x35bd 0x101 b'\\\\?\\HID#VID_35BD&PID_0101&MI_02#d&3410c40a&0&0000#{4d1e55b2-f16f-11cf-88cb-001111000030}'


Prompt:
<task-notification>
<task-id>bcje1sg00</task-id>
<tool-use-id>toolu_01TKev2XeyM749CvT1uYNg75</tool-use-id>
<output-file>C:\Users\decid\AppData\Local\Temp\claude\C--Users-decid-Documents-projects-sauna\d3fb9be1-d61d-4f88-b77c-2a2a282b11fd\tasks\bcje1sg00.output</output-file>
<status>completed</status>
<summary>Background command "Check flash tooling + HMD device state" completed (exit code 0)</summary>
</task-notification>


HMD alive: `35BD:0101` app present (also `0105`). reflash driver present. Let me read it to reuse its retry/verify logic, and read current fw version.


1	# Retry flasher: headset is already in bootloader mode (35BD:4004). Re-erase +
2	# program directly, retrying on transient write errors, then verify.
3	import sys, os, time
4	QBU = r"C:\Users\decid\Documents\projects\quick-beyond-updater"
5	sys.path.insert(0, QBU); os.chdir(QBU)
6	import hid
7	import bs_hmd_tools as t
8
9	FW = r"C:\Users\decid\Documents\projects\beyond_synaptics\dist\latest.beyondfw"
10	payload = t.load_beyondfw_file(FW)
11	print(f"payload {len(payload[0])} bytes @ 0x{payload[1]:08X}")
12
13	def boot_path():
14	    for d in hid.enumerate(vendor_id=0x35BD, product_id=0x4004):
15	        return d['path']
16	    return None
17	def app_path():
18	    for d in hid.enumerate(vendor_id=0x35BD, product_id=0x0101):
19	        return d['path']
20	    return None
21
22	ok = False
23	for attempt in range(1, 5):
24	    bp = boot_path()
25	    if bp is None:
26	        # maybe it booted to app already; if so we're done-ish, check version
27	        ap = app_path()
28	        if ap:
29	            print("device in app mode; trying to re-enter bootloader")
30	            bp = t.enter_hmd_bootloader(device_path=ap)
31	        if bp is None:
32	            print(f"attempt {attempt}: no bootloader device; waiting"); time.sleep(2); continue
33	    print(f"attempt {attempt}: flashing via {bp.decode('utf-8','ignore')[:50]}")
34	    try:
35	        ok = t.update_hmd_firmware(firmware_payload=payload, bootloader_path=bp, reset_when_done=True)
36	        if ok:
37	            print(f"attempt {attempt}: programming OK"); break
38	    except Exception as e:
39	        print(f"attempt {attempt}: {e}")
40	        time.sleep(1.5)
41
42	print("=== verify ===")
43	ver = None
44	for _ in range(20):
45	    time.sleep(1)
46	    ap = app_path()
47	    if ap:
48	        try:
49	            ver = t.get_hmd_fw_version(device_path=ap)
50	            if ver: break
51	        except Exception:
52	            pass
53	print("post-flash version:", ver)
54	print("RESULT:", "OK 0.4.1" if ver and "0.4.1" in str(ver) else f"CHECK ({ver})")
55	sys.exit(0 if (ver and "0.4.1" in str(ver)) else 5)
56

# Retry flasher: headset is already in bootloader mode (35BD:4004). Re-erase +
# program directly, retrying on transient write errors, then verify.
import sys, os, time
QBU = r"C:\Users\decid\Documents\projects\quick-beyond-updater"
sys.path.insert(0, QBU); os.chdir(QBU)
import hid
import bs_hmd_tools as t

FW = r"C:\Users\decid\Documents\projects\beyond_synaptics\dist\latest.beyondfw"
payload = t.load_beyondfw_file(FW)
print(f"payload {len(payload[0])} bytes @ 0x{payload[1]:08X}")

def boot_path():
    for d in hid.enumerate(vendor_id=0x35BD, product_id=0x4004):
        return d['path']
    return None
def app_path():
    for d in hid.enumerate(vendor_id=0x35BD, product_id=0x0101):
        return d['path']
    return None

ok = False
for attempt in range(1, 5):
    bp = boot_path()
    if bp is None:
        # maybe it booted to app already; if so we're done-ish, check version
        ap = app_path()
        if ap:
            print("device in app mode; trying to re-enter bootloader")
            bp = t.enter_hmd_bootloader(device_path=ap)
        if bp is None:
            print(f"attempt {attempt}: no bootloader device; waiting"); time.sleep(2); continue
    print(f"attempt {attempt}: flashing via {bp.decode('utf-8','ignore')[:50]}")
    try:
        ok = t.update_hmd_firmware(firmware_payload=payload, bootloader_path=bp, reset_when_done=True)
        if ok:
            print(f"attempt {attempt}: programming OK"); break
    except Exception as e:
        print(f"attempt {attempt}: {e}")
        time.sleep(1.5)

print("=== verify ===")
ver = None
for _ in range(20):
    time.sleep(1)
    ap = app_path()
    if ap:
        try:
            ver = t.get_hmd_fw_version(device_path=ap)
            if ver: break
        except Exception:
            pass
print("post-flash version:", ver)
print("RESULT:", "OK 0.4.1" if ver and "0.4.1" in str(ver) else f"CHECK ({ver})")
sys.exit(0 if (ver and "0.4.1" in str(ver)) else 5)


HMD in app mode, recoverable flash path confirmed. Writing a parametrized flasher (based on `reflash_doze.py`) — enter bootloader from app, flash with code-46 retry, verify version. First checking nothing holds `0101` (SteamVR/sauna) during flash.


cd C:/Users/decid/Documents/projects && echo "===running VR/sauna procs (must be clear for flash)===" && py -c "
import subprocess
out = subprocess.run(['tasklist'],capture_output=True,text=True).stdout.lower()
for p in ['vrserver','vrcompositor','vrmonitor','steam.exe','sauna','spatial_light']:
    print(p, 'RUNNING' if p in out else '-')
" 2>&1 | head && echo "" && echo "===current fw version===" && py -c "
import sys,os; QBU=r'C:\Users\decid\Documents\projects\quick-beyond-updater'; sys.path.insert(0,QBU); os.chdir(QBU)
import hid, bs_hmd_tools as t
ap=next((d['path'] for d in hid.enumerate(vendor_id=0x35BD,product_id=0x0101)),None)
print('app path:', ap[:40] if ap else None)
print('version:', t.get_hmd_fw_version(device_path=ap) if ap else 'NO DEVICE')
" 2>&1 | head

Check VR procs clear + current fw version


Command running in background with ID: b7m2kyy5a. Output is being written to: C:\Users\decid\AppData\Local\Temp\claude\C--Users-decid-Documents-projects-sauna\d3fb9be1-d61d-4f88-b77c-2a2a282b11fd\tasks\b7m2kyy5a.output. You will be notified when it completes. To check interim output, use Read on that file path.


<task-notification>
<task-id>b7m2kyy5a</task-id>
<tool-use-id>toolu_01LW1QK1VeXF75bfaVEBRMXR</tool-use-id>
<output-file>C:\Users\decid\AppData\Local\Temp\claude\C--Users-decid-Documents-projects-sauna\d3fb9be1-d61d-4f88-b77c-2a2a282b11fd\tasks\b7m2kyy5a.output</output-file>
<status>completed</status>
<summary>Background command "Check VR procs clear + current fw version" completed (exit code 0)</summary>
</task-notification>


1	===running VR/sauna procs (must be clear for flash)===
2	vrserver -
3	vrcompositor -
4	vrmonitor -
5	steam.exe RUNNING
6	sauna -
7	spatial_light -
8
9	===current fw version===
10	app path: b'\\\\?\\HID#VID_35BD&PID_0101&MI_02#d&3410c4'
11	version: 0.4.3
12

===running VR/sauna procs (must be clear for flash)===
vrserver -
vrcompositor -
vrmonitor -
steam.exe RUNNING
sauna -
spatial_light -

===current fw version===
app path: b'\\\\?\\HID#VID_35BD&PID_0101&MI_02#d&3410c4'
version: 0.4.3


Prompt:
<task-notification>
<task-id>b7m2kyy5a</task-id>
<tool-use-id>toolu_01LW1QK1VeXF75bfaVEBRMXR</tool-use-id>
<output-file>C:\Users\decid\AppData\Local\Temp\claude\C--Users-decid-Documents-projects-sauna\d3fb9be1-d61d-4f88-b77c-2a2a282b11fd\tasks\b7m2kyy5a.output</output-file>
<status>completed</status>
<summary>Background command "Check VR procs clear + current fw version" completed (exit code 0)</summary>
</task-notification>


Clear to flash: SteamVR not running, sauna not running, `0101` free. Current fw = **0.4.3** (the wedging build). Flashing `nonano` (full newlib, single-variable top-suspect test).


Write

# Parametrized flasher: app -> bootloader -> program (code-46 retry) -> verify.
# usage: py flash_variant.py <path-to.beyondfw> <expected-version-substr>
import sys, os, time
QBU = r"C:\Users\decid\Documents\projects\quick-beyond-updater"
sys.path.insert(0, QBU); os.chdir(QBU)
import hid
import bs_hmd_tools as t

FW = sys.argv[1]
EXPECT = sys.argv[2] if len(sys.argv) > 2 else "0.4.4"

payload = t.load_beyondfw_file(FW)
print(f"flashing {os.path.basename(FW)} -> {len(payload[0])} bytes @ 0x{payload[1]:08X}, expect {EXPECT}")

def boot_path():
    for d in hid.enumerate(vendor_id=0x35BD, product_id=0x4004):
        return d['path']
    return None
def app_path():
    for d in hid.enumerate(vendor_id=0x35BD, product_id=0x0101):
        return d['path']
    return None

# pre-flash version
ap = app_path()
print("pre-flash version:", t.get_hmd_fw_version(device_path=ap) if ap else "NO APP DEV")

ok = False
for attempt in range(1, 6):
    bp = boot_path()
    if bp is None:
        ap = app_path()
        if ap:
            print(f"attempt {attempt}: app->bootloader")
            try:
                bp = t.enter_hmd_bootloader(device_path=ap)
            except Exception as e:
                print(f"  enter_bootloader err: {e}"); time.sleep(2); continue
        if bp is None:
            print(f"attempt {attempt}: no bootloader; wait"); time.sleep(2); continue
    print(f"attempt {attempt}: programming via {bp.decode('utf-8','ignore')[:46]}")
    try:
        ok = t.update_hmd_firmware(firmware_payload=payload, bootloader_path=bp, reset_when_done=True)
        if ok:
            print(f"attempt {attempt}: programming OK"); break
    except Exception as e:
        print(f"attempt {attempt}: {e} (code-46 transient expected on 1st)")
        time.sleep(1.5)

print("=== verify ===")
ver = None
for _ in range(25):
    time.sleep(1)
    ap = app_path()
    if ap:
        try:
            ver = t.get_hmd_fw_version(device_path=ap)
            if ver:
                break
        except Exception:
            pass
print("post-flash version:", ver)
good = bool(ver and EXPECT in str(ver))
print("RESULT:", "OK" if good else f"CHECK ({ver})")
sys.exit(0 if good else 5)


File created successfully at: C:\Users\decid\Documents\projects\beyond_synaptics\dist\flash_variant.py (file state is current in your context — no need to Read it back)

# Parametrized flasher: app -> bootloader -> program (code-46 retry) -> verify.
# usage: py flash_variant.py <path-to.beyondfw> <expected-version-substr>
import sys, os, time
QBU = r"C:\Users\decid\Documents\projects\quick-beyond-updater"
sys.path.insert(0, QBU); os.chdir(QBU)
import hid
import bs_hmd_tools as t

FW = sys.argv[1]
EXPECT = sys.argv[2] if len(sys.argv) > 2 else "0.4.4"

payload = t.load_beyondfw_file(FW)
print(f"flashing {os.path.basename(FW)} -> {len(payload[0])} bytes @ 0x{payload[1]:08X}, expect {EXPECT}")

def boot_path():
    for d in hid.enumerate(vendor_id=0x35BD, product_id=0x4004):
        return d['path']
    return None
def app_path():
    for d in hid.enumerate(vendor_id=0x35BD, product_id=0x0101):
        return d['path']
    return None

# pre-flash version
ap = app_path()
print("pre-flash version:", t.get_hmd_fw_version(device_path=ap) if ap else "NO APP DEV")

ok = False
for attempt in range(1, 6):
    bp = boot_path()
    if bp is None:
        ap = app_path()
        if ap:
            print(f"attempt {attempt}: app->bootloader")
            try:
                bp = t.enter_hmd_bootloader(device_path=ap)
            except Exception as e:
                print(f"  enter_bootloader err: {e}"); time.sleep(2); continue
        if bp is None:
            print(f"attempt {attempt}: no bootloader; wait"); time.sleep(2); continue
    print(f"attempt {attempt}: programming via {bp.decode('utf-8','ignore')[:46]}")
    try:
        ok = t.update_hmd_firmware(firmware_payload=payload, bootloader_path=bp, reset_when_done=True)
        if ok:
            print(f"attempt {attempt}: programming OK"); break
    except Exception as e:
        print(f"attempt {attempt}: {e} (code-46 transient expected on 1st)")
        time.sleep(1.5)

print("=== verify ===")
ver = None
for _ in range(25):
    time.sleep(1)
    ap = app_path()
    if ap:
        try:
            ver = t.get_hmd_fw_version(device_path=ap)
            if ver:
                break
        except Exception:
            pass
print("post-flash version:", ver)
good = bool(ver and EXPECT in str(ver))
print("RESULT:", "OK" if good else f"CHECK ({ver})")
sys.exit(0 if good else 5)


Bash

cd C:/Users/decid/Documents/projects/beyond_synaptics/dist && py flash_variant.py "C:\Users\decid\Documents\projects\bs_trackA\dist\latest_nonano.beyondfw" "0.4.4" 2>&1 | tail -30

Flash nonano variant


Command running in background with ID: byx2pq3hz. Output is being written to: C:\Users\decid\AppData\Local\Temp\claude\C--Users-decid-Documents-projects-sauna\d3fb9be1-d61d-4f88-b77c-2a2a282b11fd\tasks\byx2pq3hz.output. You will be notified when it completes. To check interim output, use Read on that file path.


Flashing `nonano` (background, code-46 retry built in). Waiting for verify.


<system-reminder>Warning: the file exists but is shorter than the provided offset (1). The file has 1 lines.</system-reminder>


Flash in progress (enter-bootloader → program → reset → verify takes ~30-60s with retries). Will report when it lands.


<task-notification>
<task-id>byx2pq3hz</task-id>
<tool-use-id>toolu_01Fa8TqAuxDAZPch8NM72dSP</tool-use-id>
<output-file>C:\Users\decid\AppData\Local\Temp\claude\C--Users-decid-Documents-projects-sauna\d3fb9be1-d61d-4f88-b77c-2a2a282b11fd\tasks\byx2pq3hz.output</output-file>
<status>completed</status>
<summary>Background command "Flash nonano variant" completed (exit code 0)</summary>
</task-notification>


<owl_reachability_notice>
You have an active owl perch. When spawning subagents or doing work, use run_in_background: true so you stay reachable for incoming messages.
</owl_reachability_notice>


CAVEMAN MODE ACTIVE (full). Drop articles/filler/pleasantries/hedging. Fragments OK. Code/commits/security: write normal.


1	flashing latest_nonano.beyondfw -> 87392 bytes @ 0x00404000, expect 0.4.4
2	pre-flash version: 0.4.3
3	attempt 1: app->bootloader
4	attempt 1: programming via \\?\HID#VID_35BD&PID_4004#c&2dbb630a&2&0000#{4
5	Programming firmware...
6	attempt 1: Write error at address 0x004049E0, code: 46 (code-46 transient expected on 1st)
7	attempt 2: programming via \\?\HID#VID_35BD&PID_4004#c&2dbb630a&2&0000#{4
8	Programming firmware...
9	attempt 2: programming OK
10	=== verify ===
11	post-flash version: 0.4.3
12	RESULT: CHECK (0.4.3)
13

flashing latest_nonano.beyondfw -> 87392 bytes @ 0x00404000, expect 0.4.4
pre-flash version: 0.4.3
attempt 1: app->bootloader
attempt 1: programming via \\?\HID#VID_35BD&PID_4004#c&2dbb630a&2&0000#{4
Programming firmware...
attempt 1: Write error at address 0x004049E0, code: 46 (code-46 transient expected on 1st)
attempt 2: programming via \\?\HID#VID_35BD&PID_4004#c&2dbb630a&2&0000#{4
Programming firmware...
attempt 2: programming OK
=== verify ===
post-flash version: 0.4.3
RESULT: CHECK (0.4.3)


Flash wrote OK (attempt 2 after the expected code-46), but **version still reads 0.4.3** — because `get_hmd_fw_version` reports the **compiled `sw_ver.h`** (still 0.4.3; the agents edited CMakeLists, not `sw_ver.h`). The packager's `-v 0.4.4` is just wrapper metadata. So version string can't distinguish variants — my verify check was flawed, not necessarily the flash.

Device is in app mode (`0101` enumerates + returns a version) = a valid app booted and passed CRC. Need positive proof the *new* binary is on, not the old. Checking bs_hmd_tools for an app-CRC/readback.


cd C:/Users/decid/Documents/projects/quick-beyond-updater && echo "===bs_hmd_tools public API===" && grep -nE "^def |^    def |crc|CRC|read_|get_|app_|checksum|signature" bs_hmd_tools.py | head -40

Inspect bs_hmd_tools for readback/CRC API


Command running in background with ID: biulukziw. Output is being written to: C:\Users\decid\AppData\Local\Temp\claude\C--Users-decid-Documents-projects-sauna\d3fb9be1-d61d-4f88-b77c-2a2a282b11fd\tasks\biulukziw.output. You will be notified when it completes. To check interim output, use Read on that file path.


<task-notification>
<task-id>biulukziw</task-id>
<tool-use-id>toolu_01RWfGvYVVeju3Fok7azktt5</tool-use-id>
<output-file>C:\Users\decid\AppData\Local\Temp\claude\C--Users-decid-Documents-projects-sauna\d3fb9be1-d61d-4f88-b77c-2a2a282b11fd\tasks\biulukziw.output</output-file>
<status>completed</status>
<summary>Background command "Inspect bs_hmd_tools for readback/CRC API" completed (exit code 0)</summary>
</task-notification>


1	===bs_hmd_tools public API===
2	47:def crc8_calc(crc8_init: int, databytes: bytes) -> int:
3	48:    """Calculate CRC-8 using 0x07 as polynomial generator."""
4	49:    CRC8POLY = 0x07
5	51:        crc8_init = crc8_init ^ bb
6	53:            if crc8_init & 0x80:
7	54:                crc8_init = (0xFF & (crc8_init << 1)) ^ CRC8POLY
8	56:                crc8_init = (0xFF & (crc8_init << 1))
9	57:    return crc8_init
10	60:def hex_id_to_str(hex_id: List[int]) -> str:
11	65:def get_hmd_serial(device_path: Optional[bytes] = None, direct_device: Optional[hid.device] = None) -> Optional[str]:
12	115:def get_hmd_fw_version(device_path: Optional[bytes] = None, direct_device: Optional[hid.device] = None, retry_time: Optional[int] = None) -> Optional[str]:
13	134:                version = get_hmd_fw_version(device_path, direct_device=direct_device)
14	194:def fw_version_indicates_bootloader(version_str: str) -> bool:
15	199:def get_utility_path():
16	210:def get_utility_beyondfw_path():
17	212:    return get_utility_path() + r"/bin/latest.beyondfw"
18	215:def get_file_fw_version(file_path: str) -> str:
19	246:def _create_hid_message(hidtype: int, datalen: int, addr: int, data: bytes) -> bytes:
20	247:    """Create a HID message with CRC."""
21	250:    crcbyte = crc8_calc(0, bytes_out)
22	251:    bytes_out = bytes_out + bytes([crcbyte])
23	255:def _erase_8kb_block(device: hid.device, erase_addr: int) -> bool:
24	258:    crcbyte = crc8_calc(0, bytes_out)
25	259:    bytes_out = bytes_out + bytes([crcbyte])
26	266:def _erase_16kb_block(device: hid.device, erase_addr: int) -> bool:
27	269:    crcbyte = crc8_calc(0, bytes_out)
28	270:    bytes_out = bytes_out + bytes([crcbyte])
29	277:def _erase_sector(device: hid.device, erase_addr: int) -> bool:
30	280:    crcbyte = crc8_calc(0, bytes_out)
31	281:    bytes_out = bytes_out + bytes([crcbyte])
32	290:def _erase_blocks(device: hid.device, erase_addr: int, bytes_to_erase: int) -> bool:
33	304:def _erase_app_by_blocks(device: hid.device, erase_addr: int, bytes_to_erase: int) -> bool:
34	322:def _erase_app_full(device: hid.device) -> bool:
35	334:def load_beyondfw_file(file_path: str) -> Tuple[bytearray, int]:
36	365:def _get_existing_bootloader_paths() -> set:
37	376:def _wait_for_new_bootloader(existing_paths: set, timeout_seconds: int = 10) -> Optional[bytes]:
38	397:def device_is_beyond(device_path: bytes) -> int:
39	416:def enter_hmd_bootloader(device_path: Optional[bytes] = None, direct_device: Optional[hid.device] = None, confirm_bootloader: bool = True) -> Optional[bytes]:
40	443:        in_bootloader = fw_version_indicates_bootloader(get_hmd_fw_version(direct_device=direct_device))
41	448:        existing_bootloaders = _get_existing_bootloader_paths()
42

===bs_hmd_tools public API===
47:def crc8_calc(crc8_init: int, databytes: bytes) -> int:
48:    """Calculate CRC-8 using 0x07 as polynomial generator."""
49:    CRC8POLY = 0x07
51:        crc8_init = crc8_init ^ bb
53:            if crc8_init & 0x80:
54:                crc8_init = (0xFF & (crc8_init << 1)) ^ CRC8POLY
56:                crc8_init = (0xFF & (crc8_init << 1))
57:    return crc8_init
60:def hex_id_to_str(hex_id: List[int]) -> str:
65:def get_hmd_serial(device_path: Optional[bytes] = None, direct_device: Optional[hid.device] = None) -> Optional[str]:
115:def get_hmd_fw_version(device_path: Optional[bytes] = None, direct_device: Optional[hid.device] = None, retry_time: Optional[int] = None) -> Optional[str]:
134:                version = get_hmd_fw_version(device_path, direct_device=direct_device)
194:def fw_version_indicates_bootloader(version_str: str) -> bool:
199:def get_utility_path():
210:def get_utility_beyondfw_path():
212:    return get_utility_path() + r"/bin/latest.beyondfw"
215:def get_file_fw_version(file_path: str) -> str:
246:def _create_hid_message(hidtype: int, datalen: int, addr: int, data: bytes) -> bytes:
247:    """Create a HID message with CRC."""
250:    crcbyte = crc8_calc(0, bytes_out)
251:    bytes_out = bytes_out + bytes([crcbyte])
255:def _erase_8kb_block(device: hid.device, erase_addr: int) -> bool:
258:    crcbyte = crc8_calc(0, bytes_out)
259:    bytes_out = bytes_out + bytes([crcbyte])
266:def _erase_16kb_block(device: hid.device, erase_addr: int) -> bool:
269:    crcbyte = crc8_calc(0, bytes_out)
270:    bytes_out = bytes_out + bytes([crcbyte])
277:def _erase_sector(device: hid.device, erase_addr: int) -> bool:
280:    crcbyte = crc8_calc(0, bytes_out)
281:    bytes_out = bytes_out + bytes([crcbyte])
290:def _erase_blocks(device: hid.device, erase_addr: int, bytes_to_erase: int) -> bool:
304:def _erase_app_by_blocks(device: hid.device, erase_addr: int, bytes_to_erase: int) -> bool:
322:def _erase_app_full(device: hid.device) -> bool:
334:def load_beyondfw_file(file_path: str) -> Tuple[bytearray, int]:
365:def _get_existing_bootloader_paths() -> set:
376:def _wait_for_new_bootloader(existing_paths: set, timeout_seconds: int = 10) -> Optional[bytes]:
397:def device_is_beyond(device_path: bytes) -> int:
416:def enter_hmd_bootloader(device_path: Optional[bytes] = None, direct_device: Optional[hid.device] = None, confirm_bootloader: bool = True) -> Optional[bytes]:
443:        in_bootloader = fw_version_indicates_bootloader(get_hmd_fw_version(direct_device=direct_device))
448:        existing_bootloaders = _get_existing_bootloader_paths()


Prompt:
<task-notification>
<task-id>biulukziw</task-id>
<tool-use-id>toolu_01RWfGvYVVeju3Fok7azktt5</tool-use-id>
<output-file>C:\Users\decid\AppData\Local\Temp\claude\C--Users-decid-Documents-projects-sauna\d3fb9be1-d61d-4f88-b77c-2a2a282b11fd\tasks\biulukziw.output</output-file>
<status>completed</status>
<summary>Background command "Inspect bs_hmd_tools for readback/CRC API" completed (exit code 0)</summary>
</task-notification>


No firmware readback API exists — the only on-device identifier is the compiled `sw_ver.h`, and all 4 variants compile as 0.4.3, so I can't confirm *which* binary is running (risk: a silently-failed flash leaves the old wedging build on → false "still wedges"). Fix: rebuild each variant with a **distinct `sw_ver.h` version** so `get_hmd_fw_version` proves the flash took.

Rebuilding all 4 with unique versions (background agent):


Agent

Rebuild 4 variants w/ unique versions

Prompt:
Rebuild 4 Beyond MCU firmware variants, each with a UNIQUE compiled version so the running firmware is identifiable on-device. NO flashing, NO git commits. Produce 4 .beyondfw files.

WHY: `get_hmd_fw_version` reports the version compiled into `src/sw_ver.h` (currently MAJOR=0 MINOR=4 PATCH=3 → "0.4.3"), NOT the packager's -v label. All current variant .beyondfw report 0.4.3, so we can't confirm which flashed. Bumping PATCH per variant fixes this.

WORKTREE: C:\Users\decid\Documents\projects\bs_trackA (exists, detached at 0.4.3 commit 67bcafd). CMakeLists.txt may hold prior edits — for EACH variant, start by resetting BOTH files to the original 0.4.3 state, then apply that variant's edits:
  `cd C:/Users/decid/Documents/projects/bs_trackA && git show HEAD:CMakeLists.txt > CMakeLists.txt && git show HEAD:src/sw_ver.h > src/sw_ver.h`

TOOLCHAIN PATH (bash): `export PATH="/c/Program Files (x86)/Arm GNU Toolchain arm-none-eabi/12.2 mpacbti-rel1/bin:$LOCALAPPDATA/Microsoft/WinGet/Links:$PATH"`

ORIGINAL CMakeLists.txt reference points:
- line ~21: COMPILER_FLAGS list ENDS with `-ffast-math -mlong-calls)`
- line ~28: `add_definitions(... -D__SAMG55G19__ ...)`  (typo; chip is J19)
- GNU branch (~lines 41-47): `string(APPEND CMAKE_EXE_LINKER_FLAGS " --specs=nano.specs")` → this is what links newlib-nano. Comment it out to get FULL newlib.
sw_ver.h has `#define MINOR_VERSION 4` and `#define PATCH_VERSION 3` — change PATCH_VERSION per variant.

THE 4 VARIANTS (reset both files, then apply, then clean build `rm -rf out/build`, reconfigure, build Release, package):

1. **nonano** → PATCH_VERSION 4 (version 0.4.4). CMakeLists: remove `--specs=nano.specs` (full newlib). KEEP -ffast-math, -mlong-calls, __SAMG55G19__. Package dist/latest_nonano.beyondfw, `-v 0.4.4`.
2. **matchofficial** → PATCH_VERSION 5 (0.4.5). CMakeLists: remove --specs=nano.specs AND remove -ffast-math AND remove -mlong-calls AND __SAMG55G19__→__SAMG55J19__. Package dist/latest_matchofficial.beyondfw, `-v 0.4.5`.
3. **nofastmath** → PATCH_VERSION 6 (0.4.6). CMakeLists: KEEP --specs=nano.specs (nano), remove ONLY -ffast-math. Keep -mlong-calls, G19. Package dist/latest_nofastmath.beyondfw, `-v 0.4.6`.
4. **fullfix** → PATCH_VERSION 7 (0.4.7). CMakeLists: KEEP nano, remove -ffast-math, remove -mlong-calls, G19→J19. Package dist/latest_fullfix.beyondfw, `-v 0.4.7`.

BUILD: `cmake --preset arm-gcc-toolchain.cmake -DCMAKE_BUILD_TYPE=Release` then `cmake --build out/build/arm-gcc-toolchain.cmake`. RELEASE ONLY (Debug fails to link).
PACKAGE (from scripts/ dir, ABSOLUTE paths):
  `py usb_fw_packager_cli.py -o "<ABS>/dist/Beyond_AppImage_<variant>.hex" "<ABS>/out/build/arm-gcc-toolchain.cmake/beyond_synaptics.hex"`
  `py utility_fw_packager_cli.py -v <ver> "<ABS>/dist/Beyond_AppImage_<variant>.hex" "<ABS>/dist/latest_<variant>.beyondfw"`
(overwrite the existing same-named .beyondfw; use `python` if `py` missing.)

VERIFY each: `py -c "import sys; sys.path.insert(0,r'C:\Users\decid\Documents\projects\quick-beyond-updater'); import bs_hmd_tools as t; print(t.get_file_fw_version(r'<ABS path to .beyondfw>'))"` → must print the expected version (0.4.4/0.4.5/0.4.6/0.4.7). This confirms the version bump landed in the package.

REPORT BACK (concise table): for each variant — version, exact CMakeLists+sw_ver edits, build OK/fail (+first error), .beyondfw path+size, get_file_fw_version result. Leave worktree in place. No commits, no flash.


<owl_reachability_notice>
You have an active owl perch. Launch this Agent with run_in_background: true so you stay reachable for incoming messages while it works.
</owl_reachability_notice>