Driving a phone through the Android agent harness turns section 2c's fidelity
numbers into a task outcome. Same simulated device, one run per cell:
build decode "Turn on Wi-Fi." "Set an alarm"
bf16 41.0 tok/s done in 4 steps wrong app, stuck
W4A16 g128 80.0 tok/s done in 4 steps right app, no completion
W4A8 g128 86.6 tok/s turns it on, then off (x2) reaches Alarm, loops
Every build navigates home -> Settings -> Network -> Wi-Fi correctly. Only
some notice the switch now reads checked=true and call task_complete. W4A8 --
the fastest build, and the one the speed-first path recommends -- ends with
the task undone, on both runs.
So "W4A16 reproduces 2/12 greedy prompts and W4A8 1/12" was not a small
difference on a proxy metric: it is finishing versus reversing. The selector
now says so where someone choosing a build will read it, and points at
priority="fidelity" for agentic work.
Two tasks, one run per cell: enough to show the failure reproduces, not to
rank success rates.
Co-Authored-By: Claude Opus 5 (1M context) <noreply@anthropic.com>
