Architecture Documentation: System name

Adapted from arc42 v9 – the standard template for software architecture documentation (CC BY-SA 4.0, © Starke & Hruschka). Twelve sections; fill only what stakeholders need – arc42 is designed for adequacy, not completeness.

License note: adapted structure under CC BY-SA 4.0 – https://arc42.org/license/

1. Introduction and goals

1.1 Requirements overview

Top 3-5 requirements driving the architecture.

1.2 Quality goals

Priority	Quality goal	Scenario
1	e.g., Performance	p95 latency < 300ms under 1k rps
2	e.g., Maintainability	New dev productive in <1 week
3	e.g., Privacy	Zero data leaves device

1.3 Stakeholders

Role	Contact	Expectations
Product owner	@name	What they need from this doc
Dev team	@name	...
Operations	@name	...

2. Architecture constraints

Hard constraints that limit design freedom:

Constraint	Background / reason
Must run offline	Product is local-first
Browser-only storage	No backend in v1

3. Context and scope

3.1 Business context

flowchart LR
    U[User] --> S[System]
    S --> EXT[External system]

Neighbor	What it gives	What it receives
User	input	rendered output
External API	data	requests

3.2 Technical context

Channels, protocols, interfaces to the outside.

4. Solution strategy

The fundamental decisions in one page – technology choices, top-level decomposition, key quality-goal strategies. Links to the ADRs that record each decision.

5. Building block view

5.1 Level 1 – whitebox overall system

flowchart TD
    S[System] --> A[Editor module]
    S --> B[Preview renderer]
    S --> C[Storage layer]
    S --> D[Export pipeline]

Block	Responsibility
Editor	Document editing, input handling
Storage	Persistence, sync
Export	Format conversion

5.2 Level 2 – zoom into key blocks

Expand the blocks that carry complexity.

6. Runtime view

How building blocks interact in key scenarios:

sequenceDiagram
    participant E as Editor
    participant S as Storage
    participant P as Preview
    E->>S: autosave
    E->>P: changed segment
    P-->>E: rendered output

Scenario	What it shows
Startup	Init order, failure handling
Save	Write path, durability

7. Deployment view

Environment	Nodes	Deployment
Production	container on host	docker compose
Client	browser	static assets

8. Crosscutting concepts

Patterns applied system-wide:

• Error handling: strategy and boundaries
• Logging/observability: what is recorded where
• Persistence: data models, storage technology
• Security: auth model, data protection
• i18n/localization: approach

9. Architecture decisions

ADR	Decision	Status
ADR-001	Title	accepted
ADR-002	Title	superseded by ADR-005

10. Quality requirements

10.1 Quality tree

Hierarchies of quality goals (ISO 25010 structure optional).

10.2 Quality scenarios

Scenario	Stimulus	Response measure
10k-doc open	user opens file	renders < 2s

11. Risks and technical debt

Item	Type	Mitigation
Known limitation	debt	plan
Uncertain dependency	risk	mitigation

12. Glossary

Term	Definition
Term	Domain-meaning as used in this system