add script rules

docs/script_rules.md

@@ -0,0 +1,28 @@
+# Regression Test Script Rules
+
+These rules apply to every regression test script in `tests/` (pytest-based
+or plain-script style alike).
+
+## After every test group / test case
+
+1. **Restore default config values.**
+   Any register changed for the test (TPU `Debug` dataset config, RPU flash
+   config such as `Voltage_setting_Q128`/`Current_setting_Q128`, etc.) must be
+   restored to its original value before the script exits. Read the actual
+   value from the unit at setup time (not a hardcoded nominal constant) and
+   write it back on `close()`/`finally`, using the device's own
+   config-writable + rewrite flow (`wait_until_config_writable()` ->
+   `write()` -> `rewrite_config()`).
+
+2. **Don't turn off the eload/AC source - just switch back to local.**
+   Leaving TPU/RPU powered lets the operator continue on the bench without a
+   fresh power-up sequence. On close, set the voltage back to the bench-safe
+   default (50V or 48V, whichever the test group uses) then call
+   `set_local()` - never `output_off()`/`disconnect()` the supply itself
+   mid-session.
+
+3. **The script must print every step of the test as it runs.**
+   Anyone reading the terminal should be able to follow along without reading
+   the code: print before every voltage/current change, every charger
+   enable/disable, every wait, and every register read/write of consequence -
+   not just the final PASS/FAIL.