Copilot instructions

1---
2applyTo: "**/architecture/**, **/adr/**, **/*.arch.md, **/docs/architecture/**, **/ea/**"
3description: "Enterprise architecture standards: TOGAF alignment, ADR format, bounded context maps, capability maps, and architecture principles."
4---
5 
6## Context
7 
8This instruction file applies to enterprise architecture documents, Architecture Decision Records (ADRs), and strategic design artifacts. Enterprise architecture operates at the level of capability, integration pattern, and technology lifecycle — not at the level of individual class designs.
9 
10---
11 
12## Architecture Decision Records (ADRs)
13 
14All significant technical decisions must be captured as ADRs. "Significant" means: hard to reverse, affects multiple teams, or introduces a new technology.
15 
16### ADR Mandatory Format
17 
18```markdown
19# ADR-{NNN}: {Title — present tense, imperative}
20 
21## Status
22[Proposed | Accepted | Superseded by ADR-NNN | Deprecated]
23 
24## Context
25<What problem are we solving? What forces are in tension (time, cost, risk, quality)?
26What constraints are non-negotiable? 1–3 paragraphs.>
27 
28## Decision
29<State the decision in one clear sentence. Then justify it. No more than 2 paragraphs.>
30 
31## Consequences
32 
33### Positive
34- <Concrete benefit>
35- <Concrete benefit>
36 
37### Negative / Trade-offs
38- <Concrete cost or risk>
39- <What becomes harder>
40 
41## Alternatives Considered
42 
43| Option | Why Rejected |
44|--------|-------------|
45| {Option A} | {Specific reason} |
46| {Option B} | {Specific reason} |
47 
48## References
49- [Link to relevant RFC, doc, or prior ADR]
50```
51 
52ADRs are stored in `/docs/adr/ADR-NNN-{slug}.md` and are version-controlled alongside the code they govern.
53 
54---
55 
56## Bounded Context Map Standards
57 
58Every programme context map must show:
59 
601. **Bounded contexts** — named business domains with clear ownership
612. **Context relationships** — one of: Partnership, Shared Kernel, Customer-Supplier, Conformist, Anti-Corruption Layer, Open Host Service, Published Language
623. **Data ownership** — which context owns each domain entity
634. **Integration pattern** — synchronous API, event, or shared database (shared database requires ACL justification)
64 
65```markdown
66## Context Relationships
67 
68| Upstream | Downstream | Relationship Type | Integration |
69|----------|-----------|------------------|------------|
70| Customer Identity | Order Management | Customer-Supplier | REST API |
71| Order Management | Notification | Open Host Service | Domain Event |
72| Legacy Mainframe | Order Management | Anti-Corruption Layer | Adapter pattern |
73```
74 
75---
76 
77## Technology Lifecycle Classifications
78 
79| Status | Definition | Default Action |
80|--------|-----------|---------------|
81| **Invest** | Strategic technology, actively developed | Default choice for new work |
82| **Tolerate** | Works but not strategic; maintenance-only | No new projects; plan migration |
83| **Migrate** | Active migration in progress | Use only until migration complete |
84| **Eliminate** | Scheduled for retirement; no new work | Set end-of-life date |
85 
86---
87 
88## Architecture Principles Format
89 
90```markdown
91## Principle: {Name}
92 
93**Statement:** {One sentence, imperative.}
94 
95**Rationale:** {Why this principle exists. What problem does it prevent?}
96 
97**Implications:**
98- {Concrete rule that follows from this principle}
99- {Another concrete rule}
100 
101**Violations require:** ARB approval and documented exception in the relevant ADR.
102```
103 
104---
105 
106## PACE Layer Model
107 
108Classify all systems by business volatility:
109 
110| Layer | Change Frequency | Examples | Architecture Style |
111|-------|-----------------|---------|-------------------|
112| **Systems of Record** | Years | Core banking, GL, HR | Monolith or stable microservices |
113| **Systems of Differentiation** | Months | Customer portal, mobile app | Microservices, API-first |
114| **Systems of Innovation** | Weeks | Experimentation, AI features | Serverless, event-driven |
115 
116---
117 
118## Integration Patterns by PACE Layer
119 
120| From \ To | Systems of Record | Systems of Differentiation | Systems of Innovation |
121|-----------|------------------|--------------------------|----------------------|
122| Systems of Record | Sync API or file | Async event or ACL | Read-only export |
123| Systems of Differentiation | ACL + Sync API | Async event bus | Event subscription |
124| Systems of Innovation | Read-only API | Event subscription | Direct API |
125 
126Anti-pattern: direct database access across PACE layers creates hidden coupling.
127