Preserve delayed PortableValue raw JSON on checkpoint re-serialization to avoid large-int/type-fidelity loss

[PratikDhanave]

What

PortableValue.MarshalJSON called Any() before checking whether the value was still in its delayed json.RawMessage form. For a delayed value whose TypeID is unregistered (or whose content is any-typed/map-shaped), decodeKnownPortableType returns false and Any() falls back to a generic json.Unmarshal into any, yielding map[string]any + float64. That decoded value is never a json.RawMessage, so the existing raw-preserving branch was dead and MarshalJSON re-encoded lossily.

This makes a durable-JSON restore -> re-checkpoint cycle non-idempotent: an untouched delayed value is re-emitted with different bytes, and any int64/uint64 above 2^53 is truncated through float64.

The fix short-circuits on the retained json.RawMessage (when no deserialized cache exists) before calling Any(), re-emitting the original wire bytes verbatim.

Why (parity)

This matches .NET, which retains the incoming JsonElement and re-emits it verbatim on re-serialization rather than round-tripping through a decoded numeric/object representation. The Go delayed-deserialization path is meant to have the same "carry the bytes until someone reads them" semantics; before this change the marshal step broke that.

Tests

Added TestPortableValueMarshal_PreservesUntouchedDelayedRawJSON in workflow/portable_test.go: it builds wire JSON for a delayed value with an unregistered TypeID and a large integer (9007219254740993, > 2^53), unmarshals into a PortableValue (asserting Delayed()), re-marshals it without any typed access, and asserts the re-emitted Value bytes are byte-identical to the original. Pre-fix it truncates to 9007219254740992; post-fix it is byte-identical.

go build ./..., go vet ./workflow/..., and go test ./workflow/... all pass.

[Copilot]

Pull request overview

This PR fixes workflow.PortableValue JSON re-serialization for delayed values by preserving the original json.RawMessage bytes when the value was never read/deserialized, preventing precision/type-fidelity loss (notably for integers > 2^53) during a restore → re-checkpoint cycle.

Changes:

• Short-circuit PortableValue.MarshalJSON to re-emit the retained json.RawMessage verbatim when v.any is raw JSON and v.cache is still unset.
• Add a regression test covering an unregistered TypeID with a large integer to ensure re-marshaling preserves the original numeric bytes.

Reviewed changes

Copilot reviewed 2 out of 2 changed files in this pull request and generated no comments.

File	Description
workflow/portable.go	Preserves untouched delayed raw JSON during MarshalJSON to avoid lossy generic decoding.
workflow/portable_test.go	Adds a regression test ensuring large-integer fidelity is preserved for delayed/unregistered values.

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[github-actions]

API Consistency Review — Parity Approved ✅

This PR fixes a bug in the internal MarshalJSON logic of PortableValue (short-circuiting on the retained json.RawMessage before calling Any()). No exported Go APIs, types, or public signatures were added or changed.

Parity assessment: The fix aligns Go with the documented .NET behavior — retaining the incoming serialized representation and re-emitting it verbatim during re-serialization rather than round-tripping through a decoded numeric form. This is a correctness fix that restores semantic parity with .NET's JsonElement carry-through behavior, not a behavioral divergence.

No parity issues found. parity-approved label is already present and remains correct. public-api-change label is not warranted — no exported surface changed.

Generated by Go API Consistency Review Agent · sonnet46 · 12.4 AIC · ⌖ 5.54 AIC · ⊞ 5.7K · ◷