The cross-seam blocker: structured_output recorded its value in the tool
BODY, before tools/post-execute could block the call — a PostToolUse hook's
block turned the logged result into isError while readResult still returned
structured success and the continuation veto ended the turn.
Two-phase commit: the body validates and STAGES (RunState.pending); a fourth
runtime listener on tools/post-execute — prepend, so await next() returns the
composed final decision — promotes the stage to captured only on an accepted
call, and clears it on every path. A block now yields a consistent pair: the
model and log see the isError feedback, the run settles error with no
structured value, and the turn continues so the model can react. Regressions:
block denies the capture end-to-end; accept-with-replacement still commits.