Index

Operational Bottlenecks Addressed

Infrastructure

Technical documentation of the three functional components: the ledger engine, the marketplace orchestration layer and the analytical layer.

1. Ledger Engine

The ledger is an append-only store of double-entry records. Each business event produces one or more entries whose debits and credits sum to zero per currency. Existing entries are never modified or deleted; corrections are expressed as reversing entries that reference the original entry identifier.

1.1 Entry structure

entry_id        UUIDv7, time-ordered
event_id        source event identifier (idempotency key)
account_id      chart-of-accounts reference
direction       DEBIT | CREDIT
amount_minor    signed 64-bit integer, minor currency units
currency        ISO 4217 alpha-3
value_date      date of economic effect
booked_at       UTC timestamp, microsecond precision
reverses        entry_id | null
digest          SHA-256 over canonical serialization + previous digest

The digest field chains each entry to its predecessor within a partition. Any alteration of historical data changes every subsequent digest, which makes tampering detectable by a linear verification pass.

1.2 Reconciliation pipeline

1. Ingestion. Statement files and API payloads are stored unmodified, hashed, and registered with source, period and receipt time.
2. Normalization. Each line is converted to the canonical schema: counterparty, reference, gross amount, fee components, net amount, currency, value date.
3. Matching. Rules run in priority order: exact reference match, composite key match (order ID + amount + currency), then fuzzy window match (amount within tolerance, date within configured days).
4. Classification. Results are labelled matched, matched with variance, or unmatched.
5. Posting. Matched items generate settlement entries. Variances generate entries against a designated variance account with the cause code attached.

1.3 Rule tolerances

2. Marketplace Orchestration

The orchestration layer receives order, stock, shipment and return events from connected sales channels and applies them to a single order state machine. Channel connectors are isolated processes; failure of one connector does not interrupt processing for the others.

2.1 Order state machine

NEW -> CONFIRMED -> ALLOCATED -> SHIPPED -> DELIVERED -> SETTLED
              \-> CANCELLED          \-> RETURN_REQUESTED -> RETURNED -> REFUNDED

Transitions are accepted only from valid predecessor states. An out-of-order event is parked in a holding queue and re-evaluated when the missing predecessor arrives or when the hold interval expires, at which point the event is routed to the exception queue.

2.2 Event handling guarantees

• Delivery semantics: at-least-once from channel to platform; effectively-once through idempotency keys stored for 90 days.
• Ordering: guaranteed per order identifier, not guaranteed across orders.
• Back-pressure: per-connector token buckets enforce each channel's published request limits.
• Replay: any contiguous range of stored events can be re-applied to a clean projection for verification.

3. Analytical Layer

The analytical layer is a columnar read replica populated from the ledger and the order projection through change-data capture. Queries execute against the replica only; no analytical workload reaches the transactional store.

Replica lag is published as a metric. Reports that depend on a closed period query a snapshot identified by the period-close entry, which makes repeated runs return identical figures.

Architecture

Low-level description of the node layout, the host environment, request routing and the cryptographic protocols in use.

1. Node Roles

2. Host Environment

3. Request Routing

Requests enter on TCP 443 at the edge node. Nginx terminates TLS, normalizes the request line, applies size and rate limits, and selects an upstream by path prefix. Paths that match no configured route receive a static response without upstream involvement.

location /            { try_files $uri /index.html; }      # static application shell
location /api/        { proxy_pass http://app_pool; }      # application pool
location /health      { access_log off; return 204; }

client_max_body_size   1m;
limit_req_zone         $binary_remote_addr zone=perip:10m rate=20r/s;
add_header X-Content-Type-Options "nosniff" always;
add_header X-Frame-Options "DENY" always;
add_header Referrer-Policy "no-referrer" always;

3.1 Routing security controls

• Request line, header count and header size limits reject malformed requests before upstream selection.
• Only GET, HEAD and POST methods are accepted; other methods return status 405.
• Upstream pools communicate over a private network segment not routable from the public interface.
• Per-address rate limiting is applied at the edge; thresholds are logged as counters, not as client identifiers.
• Static shell responses carry a restrictive Content-Security-Policy and a fixed set of security headers.

4. Cryptographic Protocols

Session resumption uses TLS 1.3 PSK tickets with a rotating ticket key and a maximum lifetime of 12 hours. 0-RTT early data is disabled because replayable requests are not acceptable for ledger-affecting operations.

Privacy & Utility Control

Data-protection documentation: log retention, transit encryption, data minimization and utility-level controls.

1. Rolling 24-Hour Log Purge

Operational logs on edge nodes are retained for a rolling window of 24 hours. A scheduled job runs every 15 minutes and removes log segments whose newest entry is older than the window. Rotated files are overwritten before unlinking.

*/15 * * * *  root  /usr/local/sbin/log-purge --max-age 24h --overwrite /var/log/nginx /var/log/app

• Client network addresses are truncated before writing: the last octet of IPv4 and the last 80 bits of IPv6 are zeroed.
• Request bodies, query strings and authorization headers are excluded from all log formats.
• Log volumes are mounted separately and are excluded from backup jobs.

2. Transit Encryption Policy

1. All external connections require TLS 1.3. Connection attempts with earlier protocol versions are rejected during the handshake.
2. Plain HTTP on TCP 80, where enabled, returns a permanent redirect to the HTTPS origin and serves no content.
3. Connections between internal services use mutual TLS; plaintext inter-service traffic is not configured on any interface.
4. Certificate private keys are generated on the node, never transmitted, and readable only by the TLS-terminating process owner.
5. Certificate expiry is monitored; an alarm triggers 21 days before the not-after date.

3. Data Minimization

4. Utility Control

Utility controls limit the resources a single tenant or client can consume, which keeps latency of the reconciliation pipeline predictable for all tenants.

• Request rate: 20 requests per second per address at the edge, burst of 40.
• Payload size: 1 MB per API request; statement files are uploaded through a separate chunked path with a 256 MB ceiling.
• Worker concurrency: per-tenant cap on parallel reconciliation jobs, configured in the tenant profile.
• Queue depth: alarm at 10,000 pending items per tenant; ingestion pauses at 50,000 pending items.
• Connection limits: idle keep-alive timeout of 15 seconds; header and body read timeouts of 10 seconds.

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