v457 — every agent drills in its own file

Training mode drills every active agent in the same sandbox, and all of them wrote training/training.txt. Two passes therefore shared one piece of drill state: an agent that resumed at step 7 read another agent's completed output as its own step 6 result, its step 8 appended a second drill 2 passed line, and its step 9 — old_string: "drill 2 passed" — then matched both that line and the prefix of the (exact match) line another pass had written, so every retry failed with str_replace: old string appears 2 times.

Each agent now gets training/training-<agent id>.txt: the TRAINING MODE block names that exact path, the step labels are filled from it, and drillVerdict(calls, file) grades the pass against the same file, so another agent's work can neither satisfy a step nor corrupt one. A turn that was already in flight when Start was pressed gets the path appended to its steered kickoff. training/training.txt remains the default for callers with no agent.

The cache-buster bump exposed one test that had hardcoded ?v=442; contextWindow.test.mjs now reads APP_VERSION like every other suite.

JS 41 files / 1,173 assertions, PHP 33/33, docs 14/14. VERSION 456 → 457, APP_VERSION 442 → 443.