fix: skip timestamp-prefix heuristic for audit values (classic-record collision)

When typed random-access structures are off, records use classic shared
structures whose first byte can be 66 (0x42 = structure-id #2). RecordEncoder's
rocksdb metadata heuristic treats a leading 66 as a local-timestamp prefix and
strips 8 bytes, corrupting the record (decoded as null). The audit store's
getValue decodes a value that carries no on-disk timestamp prefix, so it now
passes { noMetadata: true } to skip the heuristic entirely. Surfaced by the
MQTT "can publish non-JSON" path.

Co-Authored-By: Claude Opus 4.7 <noreply@anthropic.com>

Author: kriszyp

resources/RecordEncoder.ts

@@ -262,7 +262,14 @@ export class RecordEncoder extends StructonEncoder {
 		let nextByte = buffer[start];
 		let metadataFlags = 0;
 		try {
-			if ((this.isRocksDB && nextByte === 66) || (nextByte < 32 && end > 2)) {
+			// The metadata/timestamp prefix is detected heuristically by the first byte. For rocksdb a
+			// local-timestamp prefix starts with 66 — but 66 (0x42) is also classic shared-structure
+			// record-id #2, so a timestamp-less classic record beginning with that id is misread as a
+			// timestamped record (8 bytes stripped → corrupt). Callers that pass a value known to have no
+			// prefix (e.g. the audit store's getValue) set options.noMetadata to skip the heuristic. Typed
+			// structs start at 0x20-0x3f and never hit this, which is why it only surfaces with classic
+			// structures (typed structures off).
+			if (!options?.noMetadata && ((this.isRocksDB && nextByte === 66) || (nextByte < 32 && end > 2))) {
 				// record with metadata
 				// this means that the record starts with a local timestamp (that was assigned by lmdb-js).
 				// we copy it so we can decode it as float-64; we need to do it first because if structural data

resources/auditStore.ts

@@ -563,7 +563,10 @@ export function readAuditEntry(buffer: Uint8Array, start = 0, end = undefined):
 				if (action & HAS_RECORD || (action & HAS_PARTIAL_RECORD && !fullRecord)) {
 					if (!value) {
 						value = decodeFromDatabase(
-							() => store.decoder.decode(buffer.subarray(decoder.position, end)),
+							// the audit value has no on-disk timestamp/metadata prefix (the audit entry carries
+							// its own time), so skip the prefix heuristic — otherwise a classic record whose
+							// structure-id byte is 66 (0x42) is misread as a rocksdb timestamp. See RecordEncoder.decode.
+							() => store.decoder.decode(buffer.subarray(decoder.position, end), { noMetadata: true }),
 							store.rootStore
 						);
 					}