[sx4im]

What this changes

Finishes the false-positive half of #890. Writing only a note on a Shopify order was still handed to the person as money-moving: the Bot passes billing_address left empty, and the safety matcher fired on the field name even though nothing was in it.

flatten in server/src/approvals/policy.ts no longer counts a field name when the field holds nothing (null, undefined, empty string, object or array). The rules now match the arguments actually sent, not names of fields left empty. A billing_address with something in it still matches exactly as before.

Where it runs

Pure function, no state involved.

• New state that outlives a request? None.
• What happens on the second replica? Identical outcome, no shared state involved.
• Anything serialised? Nothing new.
• Anything fanned out to a browser? No.
• New listener, port, or schedule? No.

Boundary and audit

• Every acting call still goes through the gateway: resolve, decide, audit, then act.
• New refusals and new failures each write a row. Fewer false hand-offs; no new refusal paths.
• Nothing new is trusted from the client that the server can resolve itself.

Changelog

• A line in CHANGELOG.md under Unreleased.

Proof

bun test server/tests/approvals-policy.test.ts: 33 pass, 0 fail. The new assertions (order note with billing_address: null and with billing_address: {}) fail before the fix (came back payments) and pass after. tsc --noEmit clean on server.

Refs #890