default Claude Code effort to high

max effort burns roughly 2x the wall time per turn for marginal quality
gain. high is the model's tuned default ('equivalent to not setting the
parameter' per Anthropic docs). full-send can be reintroduced as an
opt-in per-run override later if needed.

agents/claude.ts

@@ -90,10 +90,13 @@ function stripProviderPrefix(specifier: string): string {
   return slashIndex > 0 ? specifier.slice(slashIndex + 1) : specifier;
 }
 
-// `max` effort is supported on Opus 4.6 / 4.7; other models fall back to `high`.
-// claude-code deny-lists older opus/sonnet generations from `max` at invocation time.
-function resolveEffort(model: string | undefined): "max" | "high" {
-  if (model?.includes("opus")) return "max";
+// `high` is the model's tuned default ("equivalent to not setting the parameter"
+// per Anthropic docs). `max` is "absolute maximum capability with no constraints
+// on token spending" — meaningfully slower and burns more thinking budget per
+// turn. We default everyone to `high`; PRs that genuinely need full-send can
+// opt in via a future per-run override rather than paying the wall-time cost on
+// every Opus run.
+function resolveEffort(_model: string | undefined): "high" {
   return "high";
 }