feat: WithStrictDecode to reject lossy client signal decodes#116
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A client value that overflowed a Signal[T]'s narrower numeric type (e.g. 9999 into Signal[int8]) was silently truncated, and a shape mismatch was silently dropped — the typed Signal was only as safe as a best-effort decode. Add WithStrictDecode(): a client value that overflows the target int/uint/float width or whose JSON shape doesn't match the field surfaces an action error and the handler does not run, so corrupt input can't reach server state. Off by default (best-effort decode preserved). The decode is factored into decodeScalarChecked, which reports the error; decodeScalarInto wraps it and discards it so server-side store decodes keep the lenient contract. The struct-tag init path stays best-effort (author input, not untrusted client).
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Critic panel finding #4 (major; raised 3×). A client value overflowing a
Signal[T]'s narrower numeric type (e.g.9999intoSignal[int8]) was silently truncated; a shape mismatch silently dropped. The typed Signal was only as safe as a best-effort decode.Change
WithStrictDecode(): a client value that overflows the target int/uint/float width, or whose JSON shape doesn't match the field, surfaces an action error and the handler does not run — corrupt input can't reach server state.Decode is factored into
decodeScalarChecked(reports the error);decodeScalarIntowraps + discards it so server-side store decodes (StateSess/StateTab from the backplane) keep the lenient contract. The struct-taginit=path stays best-effort (author input, not untrusted client). Off by default.Tests
Full
ci-check.shgreen.