| """Server-side pH simulation for the real-hardware prototype. | |
| The current BioPatch prototype (ESP32-C3 + DHT11) measures temperature and | |
| humidity only — it has no pH electrode yet. Rather than block the end-to-end | |
| demo, we synthesise a plausible wound pH so the risk engine has all three | |
| channels. This is a *labelled simulation*, never presented as a real | |
| measurement: every reading it feeds is flagged ``ph_simulated=true`` and the | |
| value stays inside a healthy, mildly-acidic granulating-wound band. | |
| Deliberately independent of the live temperature/humidity so that warming or | |
| breathing on the sensor (which legitimately moves the real channels) can never | |
| manufacture a fake alkaline "infection signature" through the pH channel. | |
| """ | |
| from __future__ import annotations | |
| import random | |
| # Healing wound surface pH sits slightly acidic; alkaline drift is the | |
| # infection marker we do NOT want to counterfeit here. | |
| _PH_BASELINE = 6.0 | |
| _PH_NOISE_SD = 0.12 | |
| _PH_MIN = 5.6 | |
| _PH_MAX = 6.6 | |
| def simulate_ph(rng: random.Random | None = None) -> float: | |
| """Return a plausible, clearly-simulated wound pH (~5.6–6.6).""" | |
| r = rng or random | |
| value = r.gauss(_PH_BASELINE, _PH_NOISE_SD) | |
| return round(max(_PH_MIN, min(_PH_MAX, value)), 2) | |