Ask agents to surface mid-implementation decisions

Record the working preference that calls which come up during
implementation (and weren't settled in planning) should be raised and
decided together, not made unilaterally and discovered later in the diff.

Co-Authored-By: Claude Opus 4.8 (1M context) <noreply@anthropic.com>

AGENTS.md

@@ -137,6 +137,22 @@ commit. If you have two independent refinements for the same target, make
 two separate fixups. Reviewability of the intermediate state matters even
 when the end state after autosquash would be identical.
 
+## Surface mid-implementation decisions; decide them together
+
+Planning can't anticipate everything. When a decision surfaces while you're
+implementing — a design choice, a tradeoff, a scope cut, a "this turned out
+harder than expected, so maybe X" — don't quietly make the call and keep
+going, even if you have a clear recommendation and even if the call seems
+small. Stop, lay out the options and your recommendation, and let me weigh in.
+I want to make these calls _with_ you, not discover them after the fact in the
+diff.
+
+This isn't a request to stop and ask about every trivial detail; obvious
+mechanical choices with one sensible answer don't need a checkpoint. It's about
+genuine forks — the ones where a reasonable person might pick differently, or
+where you'd be trading away something the plan assumed (scope, UX, performance,
+reload behavior, …). When in doubt, surface it.
+
 ## Prefer the cleaner design over the smaller diff
 
 When a task could be implemented either by tacking onto existing code or by