Three failure modes on agy 1.0.16, all fixed by mirroring the Cursor block's
invocation discipline:
* file-reference prompt instead of inline "$(cat)" — a large review prompt
overflowed the exec arg list (rc 126).
* external 'timeout 600' wrapper — --print-timeout cannot fire before agy
creates a session, so a pre-session stall hung unbounded.
* --model from review.models.agy when set — escape hatch for a pinned model
that 404s (exit 0, empty stdout + transcript).
* stdin </dev/null so agy never blocks on a tty.
Also enrich the Step 3 empty-output stub to grep agy cli.log for a
model-availability diagnostic, and correct the stale 'no --model flag' note
plus the 'review.models.agy reserved for future' comment (the config key was
already read but never passed through).
af9069f865