added harness to support bots being able to run / test strategies.

README.md

@@ -64,6 +64,25 @@ npm run typecheck # tsc --noEmit
 Because Node strips types rather than compiling them, the codebase is restricted to **erasable
 syntax**: no `enum`, no parameter properties, no namespaces. `tsconfig.json` enforces this.
 
+### Measuring the bot
+
+```sh
+node src/sim/harness.ts 200                   # how the bot does, with the funnel
+node src/sim/compare.ts 1600 trainCapSlack=1  # one change, paired against the current bot
+```
+
+**Never judge a heuristic on an unpaired run.** Revenue has σ ≈ 9 across games, so two runs of the
+*identical* bot differ by about a point through nothing but the deal. `compare.ts` gives both
+policies the same seed and reports the per-seed difference, where σ is 5.3 — 1600 seeds puts the
+standard error at ±0.13, in under two minutes. Keep a change at **t ≥ 3**, and read the
+better/worse/identical split beside the mean: a gain carried by a few rescued games is a different
+claim from one spread across the field.
+
+Variants come from `makeDeveloperBot(tweaks)`. A tweak is **temporary** — when it measures well it
+becomes the default and the flag is deleted in the same commit; when it measures badly it is deleted
+with the finding recorded in `CHANGELOG.md`. A bot that accumulates switches nobody can account for
+is the thing this machinery exists to prevent.
+
 ## Design notes worth knowing
 
 - **The rules engine is pure.** No I/O, no clock, no sockets, and all randomness derives from one