DUSTY SPEC
Give this file to Claude every time. Every prompt starts with: Read dusty-spec.txt.

Version: 1        Last changed: ____________        By: Nolan Pinney

WHAT DUSTY IS
A palm-sized robot that sweeps crumbs off a table into a tray.
It must NEVER drive off the edge of the table.
This is my 4th grade invention project. I have to explain every line of the code
to the judges, so keep the code simple and explain it so a 4th grader gets it.

HARDWARE
- Brain: BBC micro:bit v2.
- Motor board: SparkFun moto:bit. In MakeCode, use the moto:bit extension
  (github.com/sparkfun/pxt-moto-bit).
- The motors only run after "turn motors ON" in on start, and with the switch
  on the moto:bit set to RUN MOTORS.
- Left wheel motor: moto:bit LEFT. Right wheel motor: moto:bit RIGHT.
- Invert LEFT motor: ____ (yes or no, from test T2)
- Invert RIGHT motor: ____ (yes or no, from test T2)
- Left cliff sensor: Pololu QTR-1A on pin P0, analog, 0 to 1023.
- Right cliff sensor: Pololu QTR-1A on pin P1, analog, 0 to 1023.
  Small number = table under it. Big number = no table (edge).
- Whisker switch: pin P2, digital. Set pull pin P2 to UP in on start.
  0 = wheel on the table. 1 = STOP. A loose wire also reads 1, so Dusty stops.
- Brush motor: has its own switch. The code does not control it.
- Power: USB power bank, a steady 5 volts.
- The cliff sensors sit 62 mm in front of the wheels. That is Dusty's head start.

NUMBERS I MEASURED
- Real speed at 40%: ______ mm per second (test T3)
- Drifts to the: ______ (left / right / straight) (test T3)
- Left sensor:  table ______   edge ______   (white paper, test T4)
- Right sensor: table ______   edge ______   (white paper, test T4)
- Black placemat: left ______  right ______   (test T4)
- Loop runs per second: ______ (test T5)

RULES THE CODE MUST FOLLOW
1. Safety first. Every time through the forever loop, check both cliff sensors
   and the whisker before anything else.
2. The forever loop must run at least 25 times a second (40 ms or less).
   While driving, nothing slow goes inside it: no show icon, no show number,
   no show string, no scrolling, no pause longer than the turn itself.
3. No sounds. The micro:bit plays sound out of pin P0, which scrambles the
   left sensor.
4. Calibration happens in on start: Dusty sits still on the table, waits 1
   second, reads each sensor, and sets that sensor's threshold to its table
   reading + 200. Show a check mark when ready.
5. Edge seen (either sensor above its threshold, or whisker = 1): stop both
   motors, drive backward 400 ms, spin a random 300 to 900 ms, then go on.
6. Normal speed is 40, unless the program is the speed experiment.
7. Buttons: A = random bounce. B = Spot Clean. A+B = stop.
8. Spot Clean: 8 rows. Each row is 4400 ms forward at 40. Between rows, turn 90,
   drive 570 ms, turn 90 the same way, alternating right and left. Cliff and
   whisker checks keep running the whole time.

HOW TO ANSWER ME
- Write MakeCode JavaScript for the micro:bit that I paste into
  makecode.microbit.org with the moto:bit extension added.
- Only use things that still show as blocks when I switch to Blocks.
- Put the test name at the top in a comment, like: // T3 Drive
- Explain every line so a 4th grader gets it.
- Tell me how to test it and what I should see.
- If my request breaks one of the rules above, tell me which rule before
  you write anything.