This project controls a motorized welding positioner. Safety is critical.

• Hardware NC contact on GPIO34 triggers interrupt in <0.5ms
• ISR immediately cuts ENA pin (HIGH = motor disabled) and sets g_wakePending so a dimmed backlight recovers on the next UI dim pass
• Software state machine enforces ESTOP as highest-priority state
• All state transitions validated via compare-and-swap (CAS) pattern
• UI overlay blocks all interaction during ESTOP; overlay show also calls dim_reset_activity() for full brightness

• ENA pin defaults HIGH (motor disabled) on boot
• ENA never driven LOW without ESTOP check
• Task Watchdog Timer (TWDT) on motor and safety tasks
• Stepper access protected by FreeRTOS mutex

If you discover a safety-critical bug or security vulnerability:

1. Do not open a public GitHub issue for safety-critical problems
2. Email the maintainer directly or use GitHub Security Advisories
3. Include: firmware version, reproduction steps, hardware configuration, serial log output (debug build)

• E-STOP bypass or failure to stop motor
• Unauthorized or unintended motor start or motion
• State machine corruption allowing unsafe transitions
• Any flaw that could expose motor control to untrusted input

• Safety-critical: response within 24 hours, fix within 1 week
• Non-critical: response within 1 week

• No OTA for P4 application firmware in the baseline release flow documented here
• NVS has no application-layer encryption — settings (cfg) and presets (prs) are plaintext JSON blobs in namespace wrot (same practical risk as unencrypted files on flash)