This is a submission for Weekend Challenge: Passion Edition
What I Built
The goal was to convert an existing Claude skill to Google AI. Gemini is no longer available for the free plan, so this is Google Antigravity.
Every AI coding agent has the same failure mode, no matter which model is behind it: it will state something about your codebase with total confidence and be wrong, because confidence and verification are different things, and nothing in a typical session forces the second one. It assumes a fallback path is safe because it looks like it should be. It calls a change to a shared type "additive" because the diff looks additive, without checking who actually imports it. It reports a green test suite as proof behavior is preserved, when all a green suite actually proves is that behavior is preserved for the inputs someone already thought to write down. This isn't a smart-enough-model problem. It gets worse as sessions get longer, not better, because context fills up with things that feel true simply because they were said ten minutes ago.
The Session Discipline Kit exists because "double-check your work" is an instruction an agent can nod along to and then quietly not follow, the same way a person under deadline pressure can. Prose rules get followed inconsistently. Mechanisms don't. So instead of one more paragraph in a context file asking the agent to verify before it edits, this kit wires the rule into the environment itself: a hook that blocks any edit to a file the agent hasn't actually opened and read in the current session — full stop, regardless of how confident it sounds. That one mechanism catches an entire category of mistake before it ships, rather than three weeks later when it surfaces as "weird, rare, hard to reproduce" behavior that takes four times as long to track down as the missing read would have taken.
