RST/power-on trigger: checks esp_reset_reason() at the very top of boot.
ESP32-C6 can't electrically distinguish the RST/EN button from a genuine
power-on (both report ESP_RST_POWERON -- confirmed against ESP-IDF's own
docs, ESP_RST_EXT is explicitly "not applicable"), so POWERON is treated
as "user wants to reconfigure" and routes straight to provisioning. Safe
because the device's only normal restart path is ESP_RST_DEEPSLEEP (its
own scheduled wake), and crash-type resets (brownout/watchdog/panic)
report their own distinct reasons, not POWERON -- so a flaky power supply
or transient crash won't get bounced into provisioning, only an actual
power cycle or RST press will (which plausibly means the frame is being
moved/redeployed anyway).
Auto-fallback: a new NVS-persisted consecutive-failure counter
(frame_config_record_server_failure/reset_server_failures) tracks wakes
where the tools server was unreachable. After
CONFIG_FRAME_REPROVISION_AFTER_FAILURES in a row (default 12, ~1hr at the
retry interval), the device clears its stored WiFi config and
esp_restart()s rather than calling wifi_provisioning_start() directly --
doing that inline would mean initializing the display driver a second
time in the same session (frame_client_run already did once), the same
class of double-init bug hit earlier with WiFi. The next boot's
frame_config_load() naturally reports "not provisioned" and routes
through the existing, already-tested provisioning path with a single
fresh epd_init(). Solves the "I moved the server to a new address" case
without needing USB access.
Both frame_config_save() (fresh provisioning) and any successful server
contact reset the failure counter.
Splits provisioning (softAP + captive portal + NVS-backed config) into
wifi_provisioning.c and home-network connection into frame_client.c.
/save_config now parses the form body and persists it to NVS; on boot the
device goes straight to STA mode if a config exists, retrying a few times
before falling back to provisioning if the home network is unreachable.
The provisioning AP is now always named ESPRESSO with a random per-device
password (generated once, persisted in NVS) instead of a fixed Kconfig
value, drawn from a charset that avoids visually ambiguous characters since
it'll be read off the e-ink panel and possibly typed by hand.
Moves the existing ESP-IDF captive_portal example into firmware/ to make
room for the new FastAPI server and project docs, ahead of building out the
full ESPresso Frame project (ESP32-C6 + Immich-backed e-ink photo frame).