A command that checks its own contract
A command's promises decay silently through ordinary edits. Per-command assertions plus a fixture that removes one guarantee is what makes the decay loud.
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Not every step needs the expensive model
Tier selection is not a preference, it is a function of three facts about the task. Two platform constraints rule out most of the combinations you would guess.
Bar, rail, drawer — the same destinations, chosen by window width
NavigationBar, NavigationRail and the drawer are three presentations of the same destination list. Window size decides which, and NavigationSuiteScaffold does the switching — with rules about how many destinations belong there at all.
Loading every rule up front is how none of them apply
An always-loaded rulebook competes with itself for attention. Matching the tool target and injecting only what fires turns 588 rules into the twelve that apply.
Two agents, one working tree, one disaster
Parallel agents sharing a working tree corrupt each other silently. Worktrees fix it, and cost 4.3 seconds and 364 MB each — not the 200ms the contract claims.
Reading back is not optional
An agent reporting success has usually verified the call returned, not the artifact. Reading its own output back is the check it skips most often.
A dialog is state, not a function you call
Dialogs and bottom sheets are composables that exist conditionally, not imperative calls. Modelling them as state fixes the rotation bug, the double-show bug, and the question of where the result goes.
One warm context beats five cold ones
Per-layer workers each pay full context assembly. Loading once and generating inline amortises it — and the measured saving was smaller than estimated.
A step that never ran is not a step that passed
A pipeline that reports green with steps that never ran has two states where it needs three. Not-run must block completion or it silently becomes success.
Is this derived thing current? Make it a comparison
Staleness checked by timestamp or by memory fails quietly. A digest of the declared inputs, stamped beside the output, makes currency a comparison.
Which artifact is actually the design
When several artifacts describe one screen, only the highest-fidelity one is read by codegen. Editing a lower tier looks like a change and reaches nothing.
The running app and the spec disagree, and only one is documented
Hand-editing generated source creates a divergence from the spec that nothing reports and the next regeneration silently erases. The fix belongs upstream.