chore(openspec): archive engineering-docs and phase-2-production-ready changes

- engineering-docs → archive/2026-03-29-engineering-docs (63/63 tasks complete)
- phase-2-production-ready → archive/2026-03-29-phase-2-production-ready (89/89 tasks complete)
- openspec/specs/ synced with all Phase 1 + Phase 2 + engineering-docs capabilities (22 specs total)

Co-Authored-By: Claude Sonnet 4.6 <noreply@anthropic.com>

openspec/changes/archive/2026-03-29-engineering-docs/specs/architecture-guide/spec.md

@@ -0,0 +1,35 @@
+## ADDED Requirements
+
+### Requirement: System architecture document
+The system SHALL include a document (`docs/engineering/02-architecture.md`) that describes the full system architecture: components, their responsibilities, how they communicate, and the deployment topology.
+
+#### Scenario: Component diagram present
+- **WHEN** a new engineer reads 02-architecture.md
+- **THEN** they SHALL find an ASCII or Mermaid component diagram showing all major components (API server, PostgreSQL, Redis, Vault, OPA, Web Dashboard, Prometheus, Grafana) and their connections
+
+#### Scenario: Request lifecycle explained
+- **WHEN** a new engineer reads 02-architecture.md
+- **THEN** they SHALL understand how an incoming HTTP request flows from client → Express router → middleware chain → controller → service → repository → database and back
+
+#### Scenario: Data flow for authentication described
+- **WHEN** a new engineer reads 02-architecture.md
+- **THEN** they SHALL understand the OAuth 2.0 Client Credentials flow: client presents credentials → token service validates → Redis checked for existing token → JWT signed and returned
+
+#### Scenario: Deployment topology covered
+- **WHEN** a new engineer reads 02-architecture.md
+- **THEN** they SHALL understand the multi-region deployment model (US, EU, APAC) and how Terraform provisions it
+
+### Requirement: Technology stack and ADR document
+The system SHALL include a document (`docs/engineering/03-tech-stack.md`) that lists every technology in the stack and explains why it was chosen over alternatives.
+
+#### Scenario: Every major technology documented with rationale
+- **WHEN** a new engineer reads 03-tech-stack.md
+- **THEN** they SHALL find an entry for each technology (Node.js 18, TypeScript 5.3, Express 4.18, PostgreSQL 14, Redis 7, HashiCorp Vault, OPA, React 18, Vite 5, Prometheus, Grafana, Terraform) with: what it does in the system, why it was chosen, and what was considered but rejected
+
+#### Scenario: TypeScript strict mode rationale explained
+- **WHEN** a new engineer reads 03-tech-stack.md
+- **THEN** they SHALL understand why strict mode is mandatory (safety, correctness, no implicit any) and what the consequences of violating it are
+
+#### Scenario: PostgreSQL vs Redis responsibility boundary clear
+- **WHEN** a new engineer reads 03-tech-stack.md
+- **THEN** they SHALL understand what is stored in PostgreSQL (persistent state: agents, credentials, audit logs) vs Redis (ephemeral state: active tokens, rate limit counters)