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mobile-money

agent-network mobile wallets over USSD/SMS: STK/USSD channel, agent float, trust-account ledger, tiered KYC, interoperability switches

M-Pesa, bKash, MTN MoMo

SystemTechniques · 30Primitives · 90 mobile-money Deterministic simulation testingdistributed · medium: Run the whole system in one thread under a seeded scheduler with simulated network, disk and clock, so every failure replays from its seed.›Durable job queuedistributed · medium: Persisted tasks that workers lease for a visibility timeout, ack on success and retry with backoff; at-least-once execution that survives worker and queue crashes.›Exactly once processingdistributed · medium: Idempotent producers plus transactional offset+output commits for effectively-once resultsPrimary-backup replicationdistributed · medium: One node orders all writes and ships them to standbys; the acknowledgement rule (none, one, all) sets what a crash loses, and an external arbiter decides who takes over.›Saga patterndistributed · medium: Split a cross-service operation into local transactions, each paired with an undo; on failure run the undos in reverse, or retry forward.›Transactional outboxdistributed · medium: Write the event as a row in the same local transaction as the state change; a relay publishes it later at-least-once, so state and events never diverge.›Authorization holdsfinance · medium: Pending vs posted balances: auth holds, incremental auths, partial captures and hold expiryIdempotency keysfinance · low: Client-chosen unique key per logical operation, stored with a request fingerprint and the final response, so retries replay the first result instead of acting twice.›Double-entry ledgerfinance · low: Append-only journal of transactions whose postings sum to zero per currency; balances are derived, so money can only move, never appear or vanish.›Iso 8583 messagesfinance · low: ISO 8583 card messages: MTIs, bitmaps, data elements and their encodingsHdr histogramdata-structures · low: Log-linear bucketed histograms with bounded relative error for latency percentilesIso 20022 messagesfinance · low: ISO 20022 XML payment and securities messages (pacs, pain, camt, sese): structure and validationMoney representationfinance · low: Store money as integer minor units with an explicit currency exponent, compute in wider integers, and round once with a named rounding mode.›Reconciliationfinance · low: Match internal ledger records against bank and processor statements by reference, then amount and date window; every unmatched or mismatched item becomes an exception.›Process supervisionhardware-os · low: A parent process starts services, reaps their exits and restarts them under a delay and burst-limit policy, then stops them with SIGTERM before SIGKILL.›Isolation forestmachine-learning · low: Score each record by how few random axis-aligned splits it takes to isolate it in a small forest of random trees; anomalies are few and different, so they isolate fast.›Sms encoding segmentationnetworking · low: GSM-7/UCS-2 encoding and concatenated SMS segmentation with UDHUssd session protocolnetworking · low: USSD menu session state over a telecom signalling channel with timeouts and stateless back-endsMutual TLSsecurity · low: TLS where the client also proves a certificate key, so every connection carries a verified, rotatable machine identity.›Graceful drainingsystems · low: On a termination signal, stop taking new work, finish in-flight work until a deadline, tell clients to reconnect elsewhere, then exit; clients resume from a token.›Cooperative schedulingconcurrency · low: Green threads/coroutines yielding at await points on a user-space schedulerRecord replaydistributed · low: Record every nondeterministic input (time, randomness, I/O, model and tool outputs, per-tick player input) and re-execute deterministically for debugging, replays and state rebuildPRNGs (PCG, xoshiro)numerics · low: Small, fast, statistically strong non-cryptographic generators: PCG32 and xoshiro256**, with seeding, parallel streams and unbiased ranges.›+ 23 more techniques+ 74 more primitives

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