Paymetryx Advisory
Engagement Plan · Confidential
Project Engagement Document — PMX/EN/2026/041

Building a scalable
fintech & transaction
analytics platform — in three strategic phases.

A 36-week enterprise execution plan covering core platform foundations, an AI & automation layer, and a financial services & ecosystem expansion track — engineered for a focused three-person delivery team, governed under Agile / Scrum at a quarterly cadence.

Phase I — Core Platform Foundation Phase II — AI & Automation Layer Phase III — Ecosystem Expansion
Engagement
Paymetryx Apps
Prepared for
Office of the CTO
Date of issue
13 May 2026
Document owner
Delivery Practice
01 — Executive Summary
Paymetryx Apps · Engagement Plan · 02
§ 01 / 08

Executive summary

A focused, capital-efficient build of an enterprise-grade transaction analytics platform — sequenced to derisk delivery, ship value every quarter, and leave a clean architectural seam for the financial-services marketplace that follows.

Total duration
36weeks
Across three sequential phases with 2-week sprints.
Delivery team
3FTE
Plus fractional QA, DevOps and security review.
Releasable increments
18sprints
Quarterly demo & steering review cadence.
Go-live milestones
3GA
One production cutover per phase, blue/green.

Engagement thesis

Paymetryx is positioned to convert raw terminal transaction streams into a defensible analytics product, an AI-led operations layer, and ultimately a financial-services ecosystem. The path to that outcome is not a single program — it is a sequence of three engagements, each of which must stand on its own commercially.

This plan compresses scope into the smallest credible Phase I, defers AI work until a clean data backbone exists, and reserves payment and lending integrations for a Phase III where regulatory perimeter is already mapped. The result: predictable releases, manageable risk surface, and a team of three that is not overdrawn at any point in the calendar.

Guiding principles

  • Data backbone first. No AI feature ships before its underlying dataset is governed and observable.
  • Cloud-native, single region first. Multi-region is a Phase III expansion, not a Phase I cost.
  • Compliance is a design input. PCI-DSS, ISO 27001 and local data residency are scoped from sprint zero.
  • Vendor-portable AI. Model providers are abstracted behind an internal gateway from the day they are introduced.
  • One owner per service. Every microservice has a named engineer accountable for SLOs and on-call rotation.

Phase summary at a glance

PhaseThemeDurationGo-livePrimary outcome
ICore Platform Foundation16 wksWk 16Live transaction analytics, admin portal, mobile app.
IIAI & Automation Layer10 wksWk 26AI support, predictive insights, conversational BI.
IIIEcosystem & Financial Services10 wksWk 36Payments, lending, utilities, merchant marketplace.
“Three phases. Three demonstrable products. One architecture that does not need to be rewritten when the marketplace opens.” — Delivery thesis

Critical success factors

  • Steering committee meets every 4 weeks with binding decision authority.
  • Compliance officer engaged from Sprint 0, not retrofitted before go-live.
  • Mobile + Web releases are versioned together; no parallel-track drift.
  • One environment per phase: dev → staging → prod, no shortcuts.
02 — Architecture Overview
Paymetryx Apps · Engagement Plan · 03
§ 02 / 08

Architecture overview

A layered, event-driven cloud architecture. Channel apps speak to an API gateway; services own their data; an event spine streams every transaction into the analytics estate; AI consumes governed datasets through a model gateway.

ChannelsCustomer & operator surfaces
Mobile App
iOS · Android · React Native
Admin Web Portal
Next.js · Internal SSO
Merchant Console
Phase III · Web
Partner APIs
External integrators
EdgeIdentity, routing, policy
API Gateway
Kong · Rate-limit · mTLS
Identity & Access
Keycloak · OIDC · MFA
WAF + CDN
CloudFront · Shield
Secrets & KMS
AWS KMS · Vault
Domain servicesBounded contexts
Transactions
Ledger · Postgres
Terminals
Device registry
Customers
Profile · KYC
Analytics
OLAP · ClickHouse
Notifications
SMS · Push · Email
Event spineStreaming & integration
Kafka / MSK — Transaction event stream
CDC · schemas registry · exactly-once
Workflow Engine
Temporal · saga
Integration Hub
Webhooks · ESB adapters
IntelligenceAI & data products
Feature Store
Phase II · Feast
Model Gateway
Provider-agnostic · cached
AI Agents
Support · Insight · Ops
Conversational BI
NL → SQL · Audit
Data & storagePersistence tiers
OLTP
PostgreSQL · RDS
OLAP
ClickHouse · S3
Data Lake
S3 · Iceberg · Glue
Cache & Search
Redis · OpenSearch
Object Store
Documents · receipts
PlatformRuntime & observability
Kubernetes (EKS)
Multi-AZ · auto-scale
CI / CD
GitHub Actions · ArgoCD
Observability
OpenTelemetry · Grafana
Security & Audit
SIEM · DLP · vuln-scan

Architectural tenets

  • Event-first. Every state change emits an event onto the spine; analytics is a consumer, never a sidecar.
  • Service ownership. One bounded context, one database, one team-of-one accountable engineer.
  • Stateless compute. All services scale horizontally; state lives only in the data tier.

Compliance posture

  • PCI-DSS scope minimisation. Card data tokenised at the edge; ledger holds tokens only.
  • ISO 27001 controls mapped to repo, infra and HR processes from Sprint 0.
  • Data residency. Primary region pinned; cross-border replication is opt-in per tenant.

Scalability levers

  • Horizontal partitioning of the transaction ledger by terminal-cohort and date.
  • Read-side projections in ClickHouse independently scaled from OLTP.
  • Backpressure via Kafka consumer-lag-based autoscaling on stream workers.
03 — Phase Roadmap
Paymetryx Apps · Engagement Plan · 04
§ 03 / 08

Detailed phase-wise roadmap

Each phase is independently steerable. Phase II depends on Phase I; Phase III depends on Phase I but can run partially in parallel with Phase II from Sprint 11 onwards under a controlled feature-flag regime.

Phase IWk 01 — Wk 16

Core Platform Foundation

Stand up the cloud, the data backbone and the first wave of customer-facing surfaces. Exit criteria: a real merchant processing real transactions through the live platform, with the admin portal and mobile app in production.
8 sprints5 milestonesGA Wk 16
Phase IIWk 17 — Wk 26

AI & Automation Layer

Introduce a governed model gateway, three AI agents (support, insight, ops) and a conversational analytics surface. Built on top of Phase I datasets — no new domain services.
5 sprints3 milestonesGA Wk 26
Phase IIIWk 27 — Wk 36

Ecosystem & Financial Services

Open the platform: payment gateways, a loan offering module, utility bill payments, merchant onboarding with KYC, loyalty and a reconciliation engine — all governed by a commission & subscription layer.
5 sprints4 milestonesGA Wk 36

36-week delivery timeline

Each column ≈ one calendar month. Bars indicate the active workstream and its owner-weighted intensity.

Workstream
M1
M2
M3
M4
M5
M6
M7
M8
M9
Buffer + Hypercare
Foundation & cloudP1 · Backend / DevOps
Cloud · IaC · IAM
Transaction coreP1 · Backend
Ledger · Event spine · APIs
Admin portalP1 · Full-stack
Dashboards · MIS
Mobile appP1 · Mobile / UX
iOS · Android · Auth
AI gateway & agentsP2 · AI engineer
Support · Insight · Ops
Conversational BIP2 · Full-stack
NL → SQL
Payments & gatewayP3 · Backend
PSP · webhooks
Lending & KYCP3 · Backend / AI
Underwriting · KYC
Marketplace & loyaltyP3 · Full-stack / Mobile
Add-ons · Rewards
QA, hardening, hypercareAll phases
Phase I HC
P2 HC
P3 HC
03.1 — Phase I in detail
Paymetryx Apps · Engagement Plan · 05
§ 03.1

Phase I — Core Platform Foundation

Sixteen weeks. Eight two-week sprints. Outcome: a live, multi-tenant fintech analytics platform with terminal data flowing end-to-end, customer mobile app in stores, and an internal portal ready for operations teams.

Scope in

  • Terminal transaction ingestion, normalisation and ledger storage.
  • Real-time analytics dashboard (operator view) with 12 baseline KPIs.
  • MIS & business intelligence reports — scheduled and on-demand exports.
  • Customer mobile app (iOS + Android) — transactions, statements, profile.
  • Admin web portal — user, role, terminal and merchant administration.
  • OAuth2 / OIDC authentication, MFA, RBAC, audit log.
  • Two outbound integrations (gateway-adjacent) and one inbound webhook spec.
  • Cloud landing zone, IaC, CI/CD, observability and security baselines.

Scope out (deferred)

  • AI agents and predictive models — Phase II.
  • Payment processing, lending, utility billers — Phase III.
  • Multi-region active-active — post Phase III.

Milestones

M#MilestoneSprintDeliverable
M1.1Cloud landing zone liveS1VPC, IAM, KMS, EKS, baseline observability.
M1.2Transaction ingestion alphaS3Terminal feed → Kafka → Postgres ledger.
M1.3Admin portal betaS5Auth, RBAC, dashboards, MIS exports.
M1.4Mobile app beta (TestFlight + internal track)S6Onboarding, transactions, statements.
M1.5Phase I GAS8Prod cutover, hypercare started, runbook signed.

Acceptance criteria

01P99 transaction-to-dashboard latency < 60s.Measured at the analytics read-side.
0299.9% API availability over 14 days.Pre-GA soak in staging mirrored to prod.
03Zero criticals in pen-test.External audit before cutover.
04App-store approval secured.iOS + Android both reviewed and live.
05RPO 5 min / RTO 1 hr.Verified through restore drill.
06Operational runbook signed off.Including on-call rotation and escalation tree.
03.2 / 03.3 — Phase II & III in detail
Paymetryx Apps · Engagement Plan · 06
§ 03.2

Phase II — AI & Automation Layer

Ten weeks. Five sprints. Outcome: an AI-augmented platform whose support, operations and analytics surfaces are measurably faster and cheaper to run, with provider-agnostic governance from day one.

Workstream

  • Model Gateway. Internal façade over LLM / embedding providers; rate-limit, cache, audit, redact.
  • AI Support Assistant. Customer-facing chatbot grounded in product docs & account context.
  • AI Insight Agent. Daily automated transaction insights pushed to merchants.
  • AI Ops Agent. Workflow automation for reporting, reconciliation prep, alert triage.
  • Conversational Analytics. NL → SQL over governed metric layer, with explain-and-trace.
  • Predictive Models. Churn risk, terminal anomaly, fraud signal scoring (advisory, not blocking).
  • AI Governance. Prompt registry, output evaluation, PII redaction, jailbreak monitoring.

Milestones

M#MilestoneSprintDeliverable
M2.1Model gateway in stagingS10Provider-agnostic façade with audit + cache.
M2.2Support assistant betaS11Embedded in mobile + portal under feature flag.
M2.3Phase II GAS13Insight, ops, conversational BI in production.

Governance guardrails

  • All prompts versioned in a registry; rollback is a deploy, not a hotfix.
  • PII redaction is applied before any external call. No exceptions.
  • Every AI response carries a trace ID; audit log retains 18 months.
  • Human-in-the-loop required for ops actions with financial impact.
§ 03.3

Phase III — Ecosystem & Financial Services

Ten weeks. Five sprints. Outcome: Paymetryx becomes a platform — merchants are onboarded with KYC, third-party services plug into a commission engine, and a reconciliation engine closes the books daily.

Workstream

  • Payment Gateway integration. One primary PSP, one fallback; idempotent webhook intake.
  • Loan Offering Module. Pre-qualification, application, decisioning hand-off to a lender partner.
  • Utility Bill Payments. Biller catalogue, statement fetch, scheduled payments.
  • Merchant Onboarding & KYC. Document capture, identity verification, risk-tiered review queues.
  • Loyalty & Rewards. Earn / burn ledger, partner promotions, expiry management.
  • Subscription & Commission Engine. Plan catalogue, metered usage, revenue-share splits.
  • Financial Reconciliation Engine. Three-way match (ledger / PSP / bank), exception queues.

Milestones

M#MilestoneSprintDeliverable
M3.1Payments in sandboxS14End-to-end test charge + refund + webhook.
M3.2KYC + merchant onboarding liveS15First external merchant onboarded.
M3.3Reconciliation engine in shadow modeS17Daily reports vs. legacy; deltas explained.
M3.4Phase III GA & programme closeS18Full ecosystem live; handover to BAU.

Future expansion seams

  • Marketplace adapter pattern: every add-on speaks the same plug-in contract.
  • Multi-currency-ready ledger; activation is a config change, not a refactor.
  • Region cloning runbook prepared in Phase III but deferred to a post-engagement track.
04 — Team Allocation
Paymetryx Apps · Engagement Plan · 07
§ 04 / 08

Team allocation matrix

A three-person delivery team operating under a working-Scrum model. Roles overlap deliberately on the seams: every workstream has a primary and a back-up to absorb leave, illness, and load.

FS

Full-Stack Developer

Owns the web estate · Scrum Master

Admin web portal, analytics dashboards, MIS reports, conversational BI surface, internal tooling, and CI for web. Doubles as Scrum Master & ceremonies facilitator.

  • Primary: Web portal · Dashboards · MIS · Conversational BI
  • Backup: Mobile QA · API consumption
MO

Mobile App & UI/UX Developer

Owns the channel surfaces · Design system

Customer iOS & Android app, mobile design system, accessibility, store releases, and visual language used across both web and mobile.

  • Primary: Mobile apps · UX system · Design tokens
  • Backup: Web portal design polish · Marketplace UI
BE

Backend / API & AI Integration Engineer

Owns services, data & AI · Tech Lead

Domain services, event spine, data warehouse, AI gateway, agents, security & cloud infrastructure. Acts as Tech Lead and architectural arbiter.

  • Primary: Services · Data · AI gateway · DevOps
  • Backup: Integrations · Reconciliation engine

RACI matrix · workstream by owner

R Responsible (does the work) · A Accountable (single owner) · C Consulted · I Informed

Workstream FS MO BE QA PM/SM Notes
Cloud landing zone & IaC CIA/RIC BE leads with fractional DevOps support in Sprint 1.
Transaction core & event spine CIA/RCI Single owner — non-negotiable for ledger integrity.
Admin web portal A/RCCCI Mobile dev consulted on shared design tokens.
Analytics dashboards & MIS A/RICCI BE provides governed metric layer; FS surfaces it.
Mobile applications (iOS + Android) CA/RCCI UX/UI design system also owned here.
Identity, RBAC, audit CIA/RCI Security review at end of Phase I.
AI gateway & agents CIA/RCC Provider-agnostic; governance is a hard gate.
Conversational analytics surface A/RCRCI Shared accountability with BE — frontmost frontier.
Payment gateway & webhooks CIA/RCC Idempotency, replay, signature validation.
Loan module + KYC CRA/RCC UX-heavy; mobile dev co-owns flow design.
Loyalty & rewards RA/RCCI Customer-facing — owned from the channel surface.
Reconciliation engine CIA/RRC Runs in shadow mode for two sprints before cutover.
QA strategy & release engineering CCCA/RC Fractional QA lead — 50% in P1, 30% in P2 & P3.

QA and PM/Scrum Master are fractional, drawn from the practice bench. The three-person core team is permanent for the engagement.

05 — Sprint Plan
Paymetryx Apps · Engagement Plan · 08
§ 05 / 08

Sprint planning table

Eighteen two-week sprints, each with a single theme, a sprint goal a steering committee can read in one breath, and a primary owner per workstream. Two-week sprints with mid-sprint review at week one.

Sprint Phase Weeks Sprint goal Primary owners Exit artefact
S0PreW00Inception: chartering, environments, backlog, security scoping. PMBEProgramme charter
S1P1W01–W02Cloud landing zone, IAM, KMS, baseline observability, repos. BEDevOpsIaC merged
S2P1W03–W04Terminal ingestion alpha; event spine bootstrapped. BEFSIngest demo
S3P1W05–W06Ledger schema GA; transaction read APIs; auth scaffolding. BEFSAPI contracts
S4P1W07–W08Admin portal alpha — auth, RBAC, terminal directory. FSMOPortal alpha
S5P1W09–W10Real-time dashboards + MIS reports v1. FSBEMIS v1
S6P1W11–W12Mobile beta — onboarding, transactions, statements. MOBETestFlight build
S7P1W13–W14Integrations + notifications; pen-test & hardening. BEQAAudit report
S8P1W15–W16UAT, performance soak, Phase I production cutover. QABEFSGA release
S9P2W17–W18Hypercare close-out; model gateway design + spike. BEPMGateway ADR
S10P2W19–W20Model gateway in staging; PII redaction; audit log. BEFSGateway alpha
S11P2W21–W22AI support assistant beta in mobile + portal under flag. BEMOBeta build
S12P2W23–W24Insight agent, ops agent, predictive models (advisory). BEFSInsights v1
S13P2W25–W26Conversational BI GA; Phase II production release. FSBEQAGA release
S14P3W27–W28Payment gateway integration + webhook intake. BEFSPSP sandbox demo
S15P3W29–W30Merchant onboarding + KYC; commission engine alpha. BEMOFirst merchant
S16P3W31–W32Loan module + utility bill payments + loyalty ledger. BEMOFSAdd-ons live
S17P3W33–W34Reconciliation engine in shadow mode; subscription billing. BEQAShadow report
S18P3W35–W36Phase III GA; programme close; BAU handover. QABEFSMOBAU handover

Agile / Scrum cadence

  • Sprint length: 2 weeks. Velocity baseline: set at S2, recalibrated each phase.
  • Ceremonies: planning (Mon W1), daily stand-up (15 min), mid-sprint review (Mon W2), demo + retro (Fri W2).
  • Steering committee: every fourth Friday — binding scope and budget decisions.
  • Definition of done: code reviewed, tested ≥80% on changed lines, observability hooked, runbook updated.
  • Backlog hygiene: 1.5× sprint capacity refined; stories ≤5 points; epics traceable to milestones.

Quarterly milestones & demos

  • End of M3 (S5): internal demo — portal + dashboards live in staging.
  • End of M4 (S8): Phase I GA + executive review.
  • End of M6 (S13): Phase II GA + AI governance audit.
  • End of M9 (S18): Phase III GA + programme close-out.
Sprints S9 and S18 are deliberately scoped lighter — they absorb hypercare for the prior phase's GA and shield the team from cumulative fatigue.
06 — Technology Stack
Paymetryx Apps · Engagement Plan · 09
§ 06 / 08

Recommended technology stack

Chosen for hiring depth, vendor portability, and operational maturity. Nothing exotic — every layer has at least one second-source option pre-identified.

LayerPrimaryAlternativeRationale
MobileReact Native + ExpoNative Kotlin / SwiftSingle codebase, shared design tokens; native fallback via modules.
Web frontendNext.js · TypeScript · TanStack QueryRemix · ViteSSR for portal SEO-free internal use; strong typing across boundary.
API layerNode.js (NestJS) + GraphQL MeshGo (chi) for hot pathsProductivity-first; selectively port hot paths to Go in Phase III.
Domain servicesPython (FastAPI) + NodeJava Spring BootPolyglot by service ownership; FastAPI for AI-adjacent services.
Event streamingApache Kafka (AWS MSK)AWS KinesisSchema registry + exactly-once; portable across clouds.
OLTPPostgreSQL 16 (RDS)Aurora PGMature, predictable, supports partitioning for the ledger.
OLAP / analyticsClickHouse CloudBigQuery / SnowflakeSub-second dashboards on terminal-event volumes; cost-efficient.
Cache & searchRedis · OpenSearchMemcached · ElasticStandard pairing; OpenSearch keeps us off the licence treadmill.
Object storageAWS S3 + Iceberg tablesGCSLake-house ready for Phase II + analytics historisation.
AI / LLMInternal model gateway → Anthropic + OpenAISelf-hosted Llama on GPU poolProvider-agnostic; gateway enforces redaction and audit.
IdentityKeycloak (self-hosted) · OIDC · WebAuthn MFAAWS CognitoNo vendor lock-in for the primary IdP; Cognito is fallback only.
Workflow / orchestrationTemporalAWS Step FunctionsSaga + retries + visibility for the reconciliation engine.
Container platformKubernetes (EKS) · Helm · ArgoCDECS FargateStandard delivery model; Fargate stays as a low-cost fallback.
IaCTerraform + TerragruntPulumiHiring depth, mature module ecosystem.
CI/CDGitHub Actions → ArgoCDGitLab CIPull-based deploys; rollback is a Git revert.
ObservabilityOpenTelemetry · Grafana · Loki · Tempo · PrometheusDatadog (commercial)Vendor-portable telemetry; Datadog acceptable if budget permits.
SecuritySnyk · Trivy · Vault · Cloudflare WAF · OPA—Defence-in-depth across code, image, runtime and policy.
Test & QAPlaywright · Jest · Pytest · k6 · Detox (mobile)—End-to-end coverage on web, API, load and mobile.
Cloud providerAWS (eu-/ap- region, tenant-pinned)Azure secondary, DR-onlySkill availability, breadth of managed data services.

DevOps approach

  • Trunk-based development with short-lived branches; merge ≤ 24 hours.
  • GitOps deploys — staging and prod track environment branches; reverts roll back.
  • Three environments: dev, staging (prod-like), prod. No more.
  • Progressive delivery: feature flags + canary rollouts on every customer-facing change.
  • Disaster recovery drill quarterly: RPO 5 min, RTO 60 min, tested.

Security & compliance baselines

  • PCI-DSS scope minimisation via tokenisation; quarterly ASV scans.
  • ISO 27001 control mapping owned by the BE/Tech Lead, audited annually.
  • SAST + SCA + IaC scan + image scan on every pipeline run; no critical merges.
  • Encryption AES-256 at rest, TLS 1.3 in transit, mTLS service-to-service.
  • Audit log append-only, retained 18 months, queryable through portal.
07 — Risk & Mitigation
Paymetryx Apps · Engagement Plan · 10
§ 07 / 08

Risk & mitigation

Risk register maintained by the Tech Lead, reviewed every sprint review and every steering committee. Severity reflects residual risk after mitigation.

ID Risk Severity Phase Mitigation Owner / trigger
R-01 Three-person team is single point of failure for any single workstream. HIGH All Designated back-up per workstream; pairing rota; documented runbooks; fractional bench on call. PM / weekly capacity check
R-02 Compliance scope creep (PCI / data residency) discovered late in Phase III. HIGH P1P3 Compliance officer engaged in S0; tokenisation at the edge from S2; Phase I pen-test & audit. BE / quarterly audit
R-03 LLM provider price & latency volatility breaks AI agent unit economics. MED P2 Provider-agnostic gateway; response cache; budget-per-tenant ceilings; self-hosted fallback path. BE / monthly cost review
R-04 Payment gateway integration blocked by vendor onboarding timeline. MED P3 Begin PSP commercial conversations at end of Phase I; have second PSP as parallel option. PM / Sprint 8 gate
R-05 Mobile app store review delays Phase I GA. MED P1 Submit a TestFlight + internal-track build at S6; production submission in S7 with two-week buffer. MO / S6 submission
R-06 Data quality from terminals (missing fields, clock skew, duplicate IDs). MED P1 Schema validation at ingest; idempotency keys; dead-letter queue with operator triage UI. BE / continuous monitoring
R-07 AI hallucination causes incorrect financial advice to a customer. HIGH P2 RAG over governed sources only; output evaluation harness; advisory disclaimer in UX; human-in-the-loop for financial actions. BE / pre-GA eval
R-08 Scope inflation during steering committee reviews pulls dates left. MED All Change-request log with explicit scope/cost/date impact; default answer is "next phase". PM / each SteerCo
R-09 Cloud bill overruns from poorly bounded analytics queries. MED P1P2 Query cost budgets; per-tenant rate limits; weekly FinOps review during the first two phases. BE / weekly FinOps
R-10 Reconciliation engine in Phase III surfaces historical data discrepancies. MED P3 Shadow mode for two sprints before cutover; explainable variance reports; remediation backlog. BE + QA / S17
R-11 Knowledge concentration in the Tech Lead role. MED All Architecture Decision Records in-repo; pairing rota; quarterly bus-factor audit. PM / quarterly
R-12 Steering decisions delayed beyond four-week SLA cause sprint thrash. LOW All Default-forward decision protocol: silence past SLA = proceed; logged in minutes. PM / SteerCo charter
Risk is not eliminated by planning. It is eliminated by noticing it early, having a named owner, and accepting that one decision per sprint will turn out to be wrong — and recoverably so.
08 — Final Delivery & Go-Live
Paymetryx Apps · Engagement Plan · 11
§ 08 / 08

Final delivery & go-live plan

Three production go-lives in 36 weeks, each preceded by a 1-week UAT, a 1-week hardening window, and followed by a 2-week hypercare period. Cutovers are blue/green; rollbacks are a Git revert away.

Cutover model
B/G
Blue/green with DNS-level switch and 30-minute drain.
Rollback SLA
15min
Reverse DNS & deploy revert; data layer is non-destructive.
Hypercare window
2wks
Per phase, 24/5 on-call with 60-min SLA on Sev-1.

Phase-by-phase go-live runbook

PhaseGo-live date (rel.)Pre-cutover gateCutover planHypercare exit criteria
I End of W16 Pen-test clean; perf soak passed; UAT sign-off; runbook approved. Blue/green; mobile released to stores 7 days prior under feature flag; portal cut over via DNS. ≤2 Sev-2/week for 14 days; zero Sev-1; on-call rotation stable.
II End of W26 AI eval harness passes thresholds; PII redaction audited; cost ceilings enforced. Gradual rollout via feature flag — 5 → 25 → 100% of tenants over 7 days. Hallucination rate < baseline; cost per session within budget; CSAT non-regressive.
III End of W36 PSP certification; KYC vendor live; reconciliation shadow-mode deltas accepted. Per-module rollout: payments → onboarding → loan → utilities → loyalty over 10 days. Reconciliation closes daily with <0.1% unexplained variance; PSP success rate ≥ 99%.

Testing & QA strategy

  • Test pyramid: 70% unit · 20% integration · 10% end-to-end. Mobile uses Detox; web uses Playwright.
  • Performance: k6 load tests against staging; targets set at 3× expected peak.
  • Security: SAST + SCA + IaC scan on every PR; external pen-test before each GA.
  • UAT: 1 week per phase, scripted scenarios + exploratory sessions with business owners.
  • Chaos drills: region-AZ failure simulated in S7 and again before P3 GA.

Maintenance & BAU handover

  • Service catalogue documenting every microservice, SLO, owner, on-call and dashboard.
  • On-call rotation rolled to BAU team over the last hypercare window; shadow weeks scheduled.
  • Quarterly DR drill baked into BAU calendar; results reported to CTO.
  • Patch & upgrade SLA: critical CVEs in 48 hours, high in 7 days, others on monthly cadence.
  • Continuous improvement budget: 20% of post-launch engineering capacity reserved for tech debt.

Future expansion capability

The architecture is intentionally over-built in exactly three places: the event spine, the model gateway and the marketplace adapter contract. These are the seams along which Paymetryx is expected to scale post-engagement — into multi-region operation, into a published partner SDK, and into a fully transactional fintech marketplace. None of the post-engagement options require a rewrite of services delivered in Phases I — III; they are configuration, additional services, and commercial agreements.

The team finishes the 36 weeks with a platform that is operationally boring — and that is the highest praise an enterprise build can earn.

Post-engagement options

  • Multi-region active-active (4 weeks).
  • Partner SDK & public developer portal (6 weeks).
  • Embedded finance API for ISVs (8 weeks).
  • FX & multi-currency activation (3 weeks).
  • Data clean-room for partner analytics (6 weeks).
End of document · Paymetryx Engagement Plan · PMX/EN/2026/041
11 · 11