Pairs with the server-side header. After streaming the response body to
LittleFS, hash the file with mbedtls/sha256 (hardware-accelerated on
ESP32-S3) and compare against the server's claim. On mismatch:
- Don't update NVS_KEY_IMG_ID, so the next poll reports the old id and
the server sends 200 again with fresh bytes (natural retry, no extra
HTTP round-trip in this cycle).
- Don't draw — panel keeps whatever was up before, no garbage on the
e-ink.
- Raise NVS_KEY_ERR_BORDER so the next healthy 304 paints a clean
recovery frame with the sync-fail border.
Verification is skipped when the header is absent, so the firmware
stays compatible with any server that hasn't deployed the matching
header yet. mbedtls compiles into a native-test no-op stub (returns
empty hex), so existing native tests don't need a SHA implementation.
Two new tests: FW-17a (mismatch path) and FW-17b (missing header
backward compat). Mock String now has equalsIgnoreCase so the new
comparison compiles in native-test.
Co-Authored-By: Claude Opus 4.7 (1M context) <noreply@anthropic.com>
Three bugs fixed:
- NVS img_id now written before epd_init/draw; new draw_needed flag in NVS
survives power-loss mid-refresh so next boot re-draws from LittleFS instead
of showing stale content
- epd_sleep() now only called when display was initialized this cycle,
preventing a 60 s wait_busy() timeout on every 304 poll
- esp_task_wdt_reset() added to wait_busy() loop so the ~20 s 6-color
refresh no longer triggers the task watchdog
Also extracts normal_operation into operation.h template and adds
a native PlatformIO test suite (16 tests) covering the full response matrix.
Co-Authored-By: Claude Sonnet 4.6 <noreply@anthropic.com>
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