(try-catch node handler) runs node; on a raised exception calls (handler error)
with the reified error via Scheme guard, returns the handler value.
Co-Authored-By: Claude Opus 4.8 (1M context) <noreply@anthropic.com>
Explicit (fail reason) values flow downstream as data and are inspected with
failed?/fail-reason — distinct from raised exceptions (retry/try-catch territory).
Co-Authored-By: Claude Opus 4.8 (1M context) <noreply@anthropic.com>
Phase 2 control flow. (branch pred then else) selects then/else node by running
pred on the threaded input; named 'branch' since 'cond' is a Scheme special form.
Co-Authored-By: Claude Opus 4.8 (1M context) <noreply@anthropic.com>