Store a plain JSON copy of tool outputs that carry functions - #1642

Summary

On 11-11 at 06:51 UTC a hand-made Postgres connector's execute_query succeeded, but its tool-call log row was lost: Prisma refused it with Invalid value for argument toPostgres: We could not serialize [object Function]. A value in the result carried a toPostgres method. boundPayload measures the output with JSON.stringify, which drops functions silently, and then returned the original object (same reference) for Prisma to store.

boundPayload now notices functions (and symbols) while it serializes, through the replacer it already runs, and continues with the plain JSON copy. Outputs without them are unchanged and keep the same reference.

Changes

• audit/bound-payload.ts: flag functions/symbols during JSON.stringify; when found, work on JSON.parse(json), for both the small path and the truncated excerpt.
• audit/bound-payload.spec.ts: a row with a toPostgres function comes back as plain JSON, small and truncated.

Type

• Bug fix

Testing

• Added/updated unit tests
• npx jest src/audit/bound-payload.spec.ts in packages/backend: 8/8. npx eslint on both files clean. Full checks in CI.

Same in Cloud and self-hosted. No schema change, nothing in ee/.

Checklist

• My code follows the existing code style
• I have tested my changes locally
• All existing tests pass (npm test) (CI)
• This PR has a descriptive title