libgit2's init→push chain is deeply stack-hungry (~67 KB measured for a
trivial config write; the push is deeper). Spike 7 sized the shared main
task stack at 96 KB for it, which forced the editor build to over-reserve
~80 KB.
Move git_publish onto its own std::thread (GIT_STACK = 96 KB via
Builder::stack_size) and join it from main. This lets
CONFIG_ESP_MAIN_TASK_STACK_SIZE drop back to 12288 — the Spike-6 value
proven to run the editor plus a TLS-on-main handshake — so the editor no
longer pays for git's stack.
Hardware-verified: the push ran off-main (mbedTLS + FATFS) with no panic,
no stack overflow, and no ENOMEM on the 96 KB spawn. This retires the
earlier "time() only works on the main task" misdiagnosis for good — it
was always the default 4 KB pthread stack overflowing, never thread-vs-main.
libgit2's repository_init -> config-write -> FATFS -> wear-leveling chain
nests ~10 GIT_PATH_MAX (4 KB) stack buffers deep; a trivial config write
measured ~67 KB on hardware and overflowed the previous 48 KB, corrupting a
newlib lock handle (LoadProhibited in xQueueGenericSend). Shared with the
editor build, so this is temporary -- git should move to a dedicated
large-stack task and this can drop back to ~16 KB.
Adds the 8 MB octal PSRAM to the heap allocator (verified on the N16R8:
detected, memory-tested, 8192K pooled). OCT mode is required or init
fails; speed left at 40 MHz for a safe first enable. Prerequisite for
the git working set and the rope buffer.
Standalone bench program (src/bin/sd_fat.rs, `just flash-sd`) that mounts
FAT over the EPD's shared SPI2 bus and proves the persistence module's
atomic save: write .tmp, fsync, rename, read back and compare.
Runs SD-only: the EPD's SpiBusDriver holds an exclusive bus lock for its
lifetime, so an arbitrated SD device can't be live alongside it yet. Keeps
CRC required and maps a card that rejects CMD59 to a clear "use a genuine
card" message rather than running the user's notes over an unchecked bus.
sdkconfig gains CONFIG_FATFS_LFN_HEAP (the atomic-save .tmp name isn't valid
8.3) and, temporarily, CONFIG_LOG_MAXIMUM_LEVEL_DEBUG to read the drivers'
per-command R1 bytes during bring-up.
Standalone `wifi_tls` binary: station assoc, SNTP, then a validated
HTTPS GET to api.github.com against the esp-idf cert bundle. Gates
Spike 7 (gitoxide push). Creds come from firmware/.env via build.rs.
Generated from esp-rs/esp-idf-template for the ESP32-S3 std target.
src/main.rs toggles GPIO 2 every 500 ms and logs `blink N` over USB-
serial — the minimum bring-up surface called out in
docs/v0.1-mvp-technical.md (Spike 1: confirm toolchain, flash, and basic
GPIO). edition=2024 with rust-version=1.85.
No editor/render/git/usb/fs modules yet; those land per the spike
methodology when later spikes need them.
