The InteractionProxy `delay` setter rejected `0` via `(not (pos? value))`,
so an immediate after-delay interaction (`interaction.delay = 0`) was
refused. The model allows it: `set-delay`
(common/.../shape/interactions.cljc) only asserts `check-safe-int`, with
no positivity constraint, and `safe-int` permits 0.
Replace the guard with `(or (not (sm/valid-safe-int? value)) (neg? value))`:
it allows 0 and positive integers, rejects negatives, and rejects
non-integers cleanly (the previous `number?` check let fractional values
through, which then failed the model's `check-safe-int` assertion
downstream).
Adds a regression test (delay round-trips a positive value, then 0).
Co-authored-by: Claude Opus 4.8 <noreply@anthropic.com>
Signed-off-by: Filip Sajdak <filip.sajdak@siili.com>
