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Implementation Sequence (API-First, Public-Facing)

Status

  • Historical sequencing artifact retained for context.
  • Canonical phased execution order lives in Implementation_Roadmap.md.
  • Current execution truth lives in governance/Agent_Work_Queue.yaml and Execution_Progress.md.

Objective

Provide a build order that minimizes rework and enforces API-first delivery with security, scalability, and operability from day 1.

Guiding Rule

  • Use bounded contexts for functional decomposition.
  • Use trust boundaries for security and deployment isolation.
  • Integrate domains through versioned APIs/events only.

Phase 1: Architecture, Trust Boundaries, Tech Stack

Scope

  • Finalize target architecture and service boundaries.
  • Lock trust boundaries and identity model.
  • Lock greenfield stack and key ADRs.

Inputs

  • architecture/Architecture_v1.md
  • architecture/Tech_Stack.md
  • product/PRD.md

Deliverables

  • Approved component map.
  • ADRs for runtime, queue, workflow engine, auth model.
  • Boundary ownership map.

Exit Criteria

  • No unresolved architecture-level blockers for phase-2 readiness constraints.

Phase 2: Domain Model, State Machines, Data Flows

Scope

  • Define core aggregates and lifecycle states.
  • Define command/event flows and compensations.
  • Define tenant/region/scheduler abstractions.

Inputs

  • architecture/State_Machines.md
  • architecture/Sequence_Flows.md
  • product/PRD.md

Deliverables

  • Canonical state machine definitions.
  • Event taxonomy and idempotency strategy.
  • Data flow diagrams for critical paths.

Exit Criteria

  • Every critical workflow has explicit state transitions and failure handling.

Phase 3: API Contracts (OpenAPI + AsyncAPI)

Scope

  • Define HTTP APIs per bounded context.
  • Define event and websocket contracts.
  • Define auth scopes, error model, idempotency headers, pagination.

Inputs

  • api/openapi.draft.yaml
  • api/asyncapi.draft.yaml
  • api/API_Surface.md
  • governance/openapi.spectral.yaml

Deliverables

  • Versioned OpenAPI and AsyncAPI specs.
  • API style compliance and lint pass.
  • SDK/CLI generation smoke success.

Exit Criteria

  • Contract review signoff and zero blocking lint errors.

Phase 4: ERD and Persistence Model

Scope

  • Finalize relational model from contracts and domain behavior.
  • Define indexes/partitioning/retention strategy.
  • Define greenfield initialization plan (no legacy migration required).

Inputs

  • architecture/ERD.md
  • architecture/db_schema_v1.sql
  • architecture/Schema_Migration_Plan.md
  • architecture/Partitioning_and_Retention_Strategy.md

Deliverables

  • Physical schema draft and DDL.
  • Data initialization plan.
  • Retention and archival policy.

Exit Criteria

  • Schema supports MVP + phase-2 readiness without destructive redesign.

Phase 5: Security Architecture and Threat Model

Scope

  • Formal threat model (STRIDE or equivalent).
  • Control mapping to boundaries, APIs, data stores.
  • Secret/key management and audit requirements.

Inputs

  • Governance_Overview.md
  • governance/agent_policy.yaml
  • architecture/Architecture_v1.md

Deliverables

  • Security control matrix.
  • Required security test plan.
  • Abuse/rate-limiting policy.

Exit Criteria

  • Security owner approval for pre-build baseline.

Phase 6: DevOps and Delivery Architecture

Scope

  • Environment strategy (dev/staging/prod).
  • CI/CD workflow and policy gates.
  • Artifact signing, SBOM, release controls.

Inputs

  • governance/CI_Enforcement_Checklist.md
  • governance/reviewguard_policy_draft.yaml
  • governance/CI_Pipeline_Implementation.md

Deliverables

  • Pipeline blueprint.
  • Merge/release gate definitions.
  • Deployment topology and promotion policy.

Exit Criteria

  • Pipeline can enforce contract/security/test gates before coding scales.

Phase 7: Contract Testing and Integration Strategy

Scope

  • Contract tests for every bounded context.
  • Integration tests for critical workflows.
  • Idempotency/replay/failure-path test suites.

Inputs

  • governance/Testing_Standards.md
  • OpenAPI/AsyncAPI contracts

Deliverables

  • Test matrix bound to requirements.
  • CI stage definitions for contract/integration.

Exit Criteria

  • Test plan approved and wired into CI gates.

Phase 8: Operations and SRE Readiness

Scope

  • SLO/SLI definitions.
  • Observability standards and dashboards.
  • Runbooks, incident response, backup/restore drills.

Inputs

  • architecture/Architecture_v1.md
  • governance/CI_Enforcement_Checklist.md

Deliverables

  • SRE readiness checklist.
  • Monitoring and alerting baseline.
  • Incident and recovery runbooks.

Exit Criteria

  • Operational readiness signoff for public launch path.
  • Separate by bounded context (functional domain) for implementation ownership.
  • Overlay trust boundaries for security and deployment isolation.
  • Integrate through explicit API/event contracts only.

Suggested Initial Bounded Contexts

  • Identity & Access
  • Inventory & Placement
  • Provisioning Orchestration
  • Billing & Ledger
  • Payments
  • Terminal Gateway
  • Storage
  • Admin & Audit

Implementation Gate Rule

No feature implementation starts until Phases 1–4 are approved and Phases 5–7 have enforceable baselines in CI/policy.