sync hub push: duplicate operation tuple claimed different…

Error message

sync hub push: duplicate operation tuple claimed different sequences

What it means

The same (id, kind, entity_rev, operation_sha256) tuple appears more than once in the acked array but each occurrence claims a different seq — the hub assigned two different log positions to one operation. A tuple maps to exactly one sequence by construction. Caught in validatePushResponse before stamping; flush() backs off and retries. Persistent occurrences point to a hub append/dedupe bug (e.g. the (origin_device, kind, origin_id, rev) dedupe failing under retries).

Solutions

Reproduce with a duplicate POST of the same op body and inspect how many acks/seqs the hub returns
On the hub, make the (origin_device, kind, origin_id, rev) dedupe atomic with the append (unique constraint or transactional check)
If duplicate log entries already exist, compact/repair the hub log before clients can converge
Until fixed, expect the client to safely reject and retry — no local corruption occurs

Defensive patterns

Strategy: try-catch

Try / catch

if (/duplicate operation tuple claimed different sequences/.test(sync.status().lastError ?? '')) {
  // hub assigned two log positions to one op: test duplicate POST idempotency
  // against the hub, fix its dedupe, then let client retries converge
}

Prevention

Give the hub an atomic unique constraint on (origin_device, kind, origin_id, rev) covering appends
Load-test the hub with duplicate concurrent submissions of the same op
Treat any occurrence as a hub bug — the client can only safely reject and retry

When it happens

Trigger: Client retries a timed-out POST and the hub appends twice because its dedupe key is broken, then acks both positions; a hub race between duplicate submit handlers; replica divergence merging the same op at two seqs.

Common situations: Hub dedupe index missing/partial after a schema migration; retry storms during network flaps exposing a hub race; multi-region hub with non-atomic log merge.

Related errors

AI-assisted analysis of thedotmack/claude-mem@e2d1df569a (2026-08-20). Data as JSON: /api/errors/77fd47a699efdd7a. Report an issue: GitHub.

Appendix: source

Thrown at src/services/sync/CloudSync.ts:1045

        entity_rev: body.entity_rev,
        operation_sha256: op.operation_sha256,
      });
      sentCounts.set(key, (sentCounts.get(key) ?? 0) + 1);
    }

    const ackCounts = new Map<string, number>();
    const tupleSeq = new Map<string, string>();
    const seqTuple = new Map<string, string>();
    for (const ack of response.acked) {
      const key = operationTupleKey(ack);
      if (!sentCounts.has(key)) {
        throw new Error('sync hub push: 200 response contains an extra or mismatched acknowledgment tuple');
      }
      ackCounts.set(key, (ackCounts.get(key) ?? 0) + 1);

      const priorTupleSeq = tupleSeq.get(key);
      if (priorTupleSeq !== undefined && priorTupleSeq !== ack.seq) {
        throw new Error('sync hub push: duplicate operation tuple claimed different sequences');
      }
      tupleSeq.set(key, ack.seq);

      const priorSeqTuple = seqTuple.get(ack.seq);
      if (priorSeqTuple !== undefined && priorSeqTuple !== key) {
        throw new Error('sync hub push: distinct operation tuples claimed the same sequence');
      }
      seqTuple.set(ack.seq, key);
    }

    for (const [key, expected] of sentCounts) {
      const actual = ackCounts.get(key) ?? 0;
      if (actual !== expected) {
        throw new Error(
          `sync hub push: 200 response acknowledgment multiplicity mismatch (expected ${expected}, received ${actual})`
        );
      }
    }

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