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Technology and resilienceEvent-driven evidence investigationevent spine

Access-entitlement drift investigation

Roles, teams and systems evolve, leaving permissions that are individually explainable but collectively excessive or conflicting.

Approach

An identity graph compares current access with role, task and historical approval context, then produces evidence-bound revocation candidates.

Organisations, systems and operating conditions are intentionally anonymised and recomposed. The design demonstrates engineering and banking-domain reasoning; it does not represent a named client estate, vendor product or measured production result.

Overview

System overview

Typed commands, state changes and receipts cross an event spine without surrendering domain ownership.

Access-entitlement drift investigation: event-spine architecture Twelve independently owned platform services connect through a typed event and evidence spine. The design separates request admission, event ordering, capability execution, systems of record, dead-letter recovery, and an immutable receipt archive. aSystem boundary and decision authoritySchematic architecture · illustrative scenario Request and event admissionCommand-side servicesAuthoritative systemsOperations rail Channel & case eventsHTTPS · batch · streamSchema & identity gateOIDC · event versionPartition & ordering serviceentity key · watermarkBackpressure gatequota · pause envelopeadmittedlag signal Evidence ContextCompilerContext & evidenceParty RelationshipResolverIdentity & relationshipsAuthority Rules EngineAuthority & policyJourney StateCoordinatorWorkflow & custodyTyped Action BrokerIntegration & effectsDecision ReceiptLedgerEvidence & auditReasoning RouteManagerModel executionEffective-DatedKnowledge HubKnowledge & rulesBehaviour EvaluationHarnessEvaluation & releaseOutcome RecoverySupervisorResilience & recoveryOperational Read ModelWorld state & read modelsDecision ReviewWorkbenchHuman decision & operationspublishpublishpublishpublishpublishpublishconsumeconsumeconsumeconsumeconsumeconsume EVENT + STATE SPINErequest.accepted · context.qualified · authority.decided · action.dispatched · effect.readback · custody.changed Observabilitysource of recordconfigurationsource of recordservice inventorysource of recorddeploymentsource of record Dead-letter & replay queueDecision receipt archiveTrace, lag & cost telemetryIncident & custody queue
Figure 1. Typed events coordinate independently owned services without turning the event spine into a system of record. Ordering, backpressure, readback and replay stay explicit. This is an illustrative system model, not a named deployment.

Permitted workThe system may correlate events and propose recovery. Production change, privileged access and incident command remain controlled human authorities.

Consistency ruleCorrelate telemetry by service, version, environment and event time; configuration inventory is qualified, not assumed current.

Hard boundaryThe model is not a system of record, identity provider, policy authority or proof that an external effect occurred.

Deployment

Deployment

An alert or case requires evidence fan-out, deterministic triage, residual model reasoning and a defensible human disposition.

Access-entitlement drift investigation: deployment and trust-zone topology A production topology separates public edge, identity boundary, workload cluster, integration plane, data enclave and operating controls. Connections name transport and identity protocols, and a second region provides controlled failover. bDeployment topology and failure domainsLogical deployment · no measured estate data EDGE AND ACCESS PRIVATE WORKLOAD CLUSTER INTEGRATION AND DATA ENCLAVE OPERATIONS, EVIDENCE AND RECOVERY PLANE Web applicationfirewallTLS · bot · rate API ingressschema · quota Identity brokerOIDC · MFA Purpose gateclaims · consent HTTPStokensubject Regional traffic managerhealth · canary · failover Workload identity issuershort-lived service tokens Event & work queuepartition · DLQ · backpressure Secrets & key serviceenvelope encryption · rotation PartyRelationship…zonal workloadAuthority RulesEnginezonal workloadDecision ReceiptLedgerzonal workloadReasoning RouteManagerzonal workloadDecision ReviewWorkbenchzonal workloadReserved workloadslotdisabledReserved workloadslotdisabledReserved workloadslotdisabled HTTPS · scoped JWT workload token async eventkey lookup IntegrationgatewaymTLSObservabilitysystem of recordconfigurationsystem of recordservice inventorysystem of recorddeploymentsystem of record Model route enclavepolicy · schema · egress Qualified data storesSQL · graph · object Trace, metric & cost pipelineOpenTelemetry · redaction Decision receipt archiveappend-only · retention Reconciliation workersreadback · replay · DLQ On-call & review queuescustody · SLA · escalation Secondary-region standbycompatible manifest telemetryreceiptsexceptions
Figure 2. Workloads remain isolated from systems of record. Short-lived identity, typed integration contracts, append-only evidence and controlled failover define the deployable boundary; the topology is schematic.
Authority checkpoint

The model cannot revoke access or infer job need; every recommendation requires accountable-owner review.

Runtime

Runtime flow

A deterministic outer workflow contains model-led work inside typed, observable calls. Dashed messages remain proposals until policy or a human grants authority.

Access-entitlement drift investigation: event processing and recovery flow A five-lane event architecture shows authoritative producers, admission and ordering, evidence qualification, decision and effect handling, and the recovery rail. Late, duplicate and failed events follow separate paths to reconciliation and replay. cRuntime protocol and control pointsProtocol model · illustrative execution Authoritative producersAdmission and orderingEvidence and decisionEffect and reviewEvidence, reconciliation and replay Observabilityevent time · source versionconfigurationevent time · source versionservice inventoryevent time · source versiondeploymentevent time · source version Schema gateversion · identity · duplicatePartitioned event logentity key · watermark Enrichment workersbounded fan-out · freshnessDecision workerrule gate · bounded score Effect or review routetyped action · custodyOutcome verifierreadback · reconcile source eventsource eventqualified readqualified read admittedorderedcontextdecision Late-event correctionreopen · append · notifyDead-letter queuefault class · ownerIdempotent replaysame key · checkpointDecision receipt ledgerversions · basis · custodyOutcome monitorlag · drift · harm invalid / faileddelayed outcomecheckpoint replaydecision evidenceeffect receipt Consistency: Pin policy and evidence versions at case open. Later corrections append and may trigger reassessment; they do not rewrite the historic basis silently.
Figure 3. Event time, admission, evidence qualification, decision and delayed outcome remain separate. Late or failed events enter correction and replay paths with preserved lineage. The paths are protocol semantics, not an observed production trace.
S

State model

Append-only case events feed a current-state projection. Evidence rows keep source, observation time, validity, correction history and narrative usage.

I

Integration choice

Use asynchronous ingestion and bounded parallel reads. Slow providers have independent timeout and circuit-breaker policy so one source cannot exhaust the case tier.

C

Consistency semantics

Pin policy and evidence versions at case open. Later corrections append and may trigger reassessment; they do not rewrite the historic basis silently.

Services

Services and interfaces

These roles are deliberately vendor-neutral. Each can be independently owned, versioned and replaced.

  1. ERG
    Identity and relationships

    Party Relationship Resolver

    Returns candidate entities and typed relationships with match features, contradictions, effective dates and non-merge evidence.

    Degraded routePreserve separate candidates and route ambiguity for review. Never collapse entities simply to complete the journey.
  2. PDS
    Authority and policy

    Authority Rules Engine

    Evaluates identity, purpose, capability, amount, risk tier and policy version; returns allow, deny, step-up or human-review with reasons.

    Degraded routeFail closed for effects and restricted data. Read-only explanation may continue only from approved public or customer-visible sources.
  3. MSG
    Model execution

    Reasoning Route Manager

    Chooses an approved model route by task, risk, evidence quality, latency budget and cost ceiling; enforces structured outputs.

    Degraded routeUse a smaller certified route, deterministic fallback or human queue. Never lower the control bar to meet latency.
  4. HRC
    Human decision and operations

    Decision Review Workbench

    Presents claims beside evidence, alternatives, uncertainty, missing information, permitted actions and current custody.

    Degraded routeRoute to a trained queue with the original sources and open work. The model summary is never the sole evidence available.
  5. DES
    Evidence and audit

    Decision Receipt Ledger

    Appends request, versions, policy result, model proposal, approval, action receipt, readback, correction and custody events under one correlation key.

    Degraded routeBlock a consequential close when mandatory evidence is missing; keep the case open with an explicit evidence defect.
Figure 4. Each service exposes a typed contract and a defined degraded route. Coordination stays in the control plane while domain ownership remains outside it.
Data

Data and records

Durable records carry provenance, authority, effect and custody without turning a transcript into an uncontrolled memory store.

Access-entitlement drift investigation: state ownership and evidence lineage Authoritative source observations feed six versioned runtime records. Each record names a single write owner. An append-only event and evidence stream builds a disposable current-state projection and supports audit replay. dState lineage, ownership and temporal validityLogical records · fields are illustrative AUTHORITATIVE INPUTS · POINT-IN-TIME QUALIFIEDObservabilitysource version · observed atconfigurationsource version · observed atservice inventorysource version · observed atdeploymentsource version · observed atqualified inputqualified inputqualified inputqualified input WRITE OWNER · Evidence Context CompilerRequest enveloperequest_idpurposeactor_refsubject_refversioned · attributable · retainedWRITE OWNER · Authority Rules EngineContext manifestcontext_idsource_refsource_versionobserved_atversioned · attributable · retainedWRITE OWNER · Typed Action BrokerCase statecase_idstatestate_versioncurrent_custodianversioned · attributable · retainedWRITE OWNER · Reasoning Route ManagerAuthority decisiondecision_idpolicy_versionrequested_capabilityoutcomeversioned · attributable · retainedWRITE OWNER · Behaviour Evaluation HarnessAction and effect receiptaction_ididempotency_keyinput_hashdispatch_statusversioned · attributable · retainedWRITE OWNER · Operational Read ModelCustody eventtransfer_idfrom_ownerto_ownerreasonversioned · attributable · retained APPEND-ONLY CASE EVENTS + DECISION RECEIPTSrequest hash · source versions · policy version · proposal · authority · effect readback · custody Operational current-state viewrebuildable projection
Figure 5. The record chain preserves source version, write ownership, authority and custody. Solid records are required in this scenario; dashed records remain compatible but dormant.
Consistency contractDomain source rule

Correlate telemetry by service, version, environment and event time; configuration inventory is qualified, not assumed current.

Choices

Trade-offs

The selected design is not universally superior. It is the safer fit for this boundary and failure cost.

  1. 01

    Optimise for fewer duplicate entities or fewer false merges

    Selected path

    Bias consequential journeys against false merge and retain unresolved candidates.

    Rejected path

    Automatically merge the highest-scoring candidate.

    Cost acceptedMore cases require clarification, but one person's authority or risk cannot silently attach to another.

  2. 02

    Reason over policy text at runtime or compile executable rules

    Selected path

    Compile stable decision logic and retain retrieval for explanation and residual ambiguity.

    Rejected path

    Ask a model to interpret the source document for every request.

    Cost acceptedRule compilation needs controlled change, but creates repeatable decisions, regression tests and clear exceptions.

  3. 03

    Use one frontier model for every step or a task-specific cascade

    Selected path

    Reserve larger models for residual reasoning after deterministic and smaller-model gates.

    Rejected path

    Send every request to the most capable available model.

    Cost acceptedRouting adds evaluation work and operational complexity, but controls cost, latency and unnecessary data exposure.

  4. 04

    Review every case or apply risk-tiered human checkpoints

    Selected path

    Keep people at irreversible, ambiguous and policy-exception points; sample lower-risk automated outcomes independently.

    Rejected path

    Require the same manual approval at every step.

    Cost acceptedRisk-tiering reduces review load but needs calibrated thresholds, sampling and immediate withdrawal of authority when drift appears.

  5. 05

    Mutable current-state record or append-only decision history

    Selected path

    Use append-only events plus a rebuildable current-state projection.

    Rejected path

    Overwrite the case row with its latest status.

    Cost acceptedReplay and storage are more complex, but point-in-time reconstruction and correction lineage remain possible.

Figure 6. Teal marks the selected route; coral dotted rules preserve the rejected alternative. Each decision states the cost accepted rather than presenting one architecture as universally superior.
Recovery

Failures and recovery

Retries are bounded by knowledge of business effect; unknown outcome remains visible, owned and independently reconciled.

Access-entitlement drift investigation: failure classification and recovery control flow Five failure sources converge on a classifier that distinguishes known no effect, known failure, unknown outcome, material evidence gaps and control-plane failure. Each state has an explicit recovery route, service degradation and evidence receipt. eFailure classification and recovery policyControl model · thresholds set by owners DETECTION POINTSEFFECT CLASSIFIERRECOVERY DECISIONSERVICE-SPECIFIC DEGRADATION Source dependencyTemporary incident access can appear as…Authority servicePolicy is unavailable, expired, or returns…Reasoning routeOutput fails schema, citation, grounding…Action pathTransport times out after dispatch & the…Evidence railReceipt or custody append fails after a… Outcome classifierattempt · idempotency · source readback ·… Known no effectSafe bounded retry with the same…Known failureNarrow, queue, compensate, or fail closed…Unknown outcomeRead back authoritative state before retry…Material evidence gapRetain custody & create an owned…Control-plane failureStop promotion or dispatch; restore the…Party Relationship ResolverPreserve separate candidates &route ambiguity for review. Nevercollapse entities simply to…Authority Rules EngineFail closed for effects &restricted data. Read-onlyexplanation may continue only from…Reasoning Route ManagerUse a smaller certified route,deterministic fallback or humanqueue. Never lower the control bar…Decision Review WorkbenchRoute to a trained queue with theoriginal sources & open work. Themodel summary is never the sole…Decision Receipt LedgerBlock a consequential close whenmandatory evidence is missing;keep the case open with an… RECOVERY RECEIPTfault origin · classification basis · owner · retry/compensation key · readback reference · residual risk · resolved at classifier evidencerecovery evidence Pattern rule: Missing materialevidence blocks a clean close. Thecase enters a completeness queue…
Figure 7. Recovery follows the known business-effect state, not the transport symptom. Every branch ends in a receipt preserving fault origin, custody and reconciliation basis.
Capacity

Performance and capacity

Actual thresholds belong to accountable service owners. The design exposes the equations and observables that those owners must baseline.

Dependent variablesOperating
envelope
  • recall and false-close rate
  • case-pack latency
  • source completeness
  • investigator queue age
Capacity relationships
  1. 01peak_enrichment_qps = peak_case_rate x sources_per_case
  2. 02review_hours = residual_cases / investigator_throughput
  3. 03evidence_storage = cases x evidence_rows x retention_window
Privacy lens

Redact secrets and customer payloads from traces while retaining identity, change and evidence metadata.

Figure 8. The variables define what must be measured before capacity or quality claims can be accepted. Relationships are analytical scaffolds, not invented targets or production results.
Operations

Release and operations

A design is production-ready only when teams can prove what happened, recover it and change it safely.

Minimum release gates
  1. 01

    failure injection and blast-radius test

  2. 02

    rollback and schema compatibility

  3. 03

    privileged-action approval

  4. 04

    incident timeline reconstruction

Figure 9. Promotion requires evidence at each gate and a compatible rollback route. No gate is implied to have passed; accountable owners set thresholds and sign the record.
Operating stateReleaseRecover
Evidence

Entitlement source, role mapping, approval lineage, usage context, conflict rules, owner decision and revocation receipt.

Human authority

Line managers and access owners approve retention or removal.

Evolution

Use shadow decisions and blind samples before allowing deterministic closes. Keep agent-touched cases under human disposition until operating evidence supports narrower review.

Ownership

Service, SRE, security, change, architecture and business-continuity owners accept recovery choices.

Figure 10. Evidence, human authority, ownership and controlled evolution remain coupled throughout operation. Removing any quadrant breaks the assurance case.