Impact analysis example
What breaks when you change Docusaurus (packages/docusaurus)?
Real arc impact output on Docusaurus (packages/docusaurus) — same structure as the homepage demo. Know blast radius before you merge.
Project: Docusaurus (packages/docusaurus) · Score: 95.6/100 (Excellent architecture) · 118 modules · 171 edges
Engineering decision simulation
Validation procedure 01 · merge vs. hold before output
Before arc impact
You plan a change to a high fan-in module in Docusaurus (packages/docusaurus). Would you merge without knowing blast radius?
Typical answer: hold — need dependency context.
After arc impact
Structured output below: score, hotspots, corridors, and high-risk modules — same field schema as the homepage proof.
Decision: confirm hold, narrow change, or inspect paths first.
Published as part of the validation record. Run locally: arc impact <file-you-are-changing>
Architectural Risk Map
Where risk accumulates by control surface — drill down Surface → Substrate → Mechanism → Evidence.
See control surfaces →Dependency evidence
Architecture visualization
Diagrams are generated from ArcSight analysis data. Dependency graph and risk map show key modules; subsystem view shows high-level structure.
Architecture score & metrics
Score: 95.6/100 · Stability: 43/100 · Status: healthy · Confidence: 100%
- Dependency cycles: 8
- Duplicate authorities: 3
Modules to inspect
One row per module. Fan-in is direct dependents. Blast radius is downstream modules reachable from that file.
- src/server/site9 dependents
- src/commands/swizzle/common8 dependents
- src/server/plugins/init5 dependents
- src/commands/swizzle/prompts4 dependents
- src/server/plugins/configs3 dependents
- src/server/translations/translations3 dependents
- src/commands/swizzle/actions3 dependents
- src/commands/swizzle/components3 dependents
- src/server/plugins/configs24 modules
- src/server/plugins/init16 modules
- src/server/translations/translations16 modules
- src/server/site14 modules
- src/server/siteMessages14 modules
- src/commands/swizzle/common10 modules
- src/commands/swizzle/prompts8 modules
- src/commands/swizzle/actions8 modules
| Module | Fan-in | Blast | Risk |
|---|---|---|---|
| src/server/plugins/configs | 3 | 24 | LOW |
| src/server/plugins/init | 5 | 16 | LOW |
| src/server/translations/translations | 3 | 16 | CRITICAL |
| src/server/site | 9 | 14 | LOW |
| src/server/siteMessages | 1 | 14 | HIGH |
| src/commands/swizzle/common | 8 | 10 | HIGH |
| src/commands/swizzle/prompts | 4 | 8 | CRITICAL |
| src/commands/swizzle/actions | 3 | 8 | CRITICAL |
| src/commands/swizzle/components | 3 | 8 | CRITICAL |
| src/commands/swizzle/tables | 2 | 8 | CRITICAL |
| src/server/plugins/moduleShorthand | 2 | LOW | |
| src/server/plugins/presets | 1 | LOW |
CLI workflow
Scan → Fix → Finish → Watch. Nothing else required.
arc scanFind issuesarc fixApply fixesarc finishResolve remainingarc watchKeep clean
Key takeaways
- •Architecture score 95.6/100 indicates a healthy structure with room to reduce cycles and violations.
- •Structural scan reports dependency cycles — inspect impact paths before refactors that cross module boundaries.
- •High fan-in modules are change-risk zones; run
arc explain <path>before refactoring. - •Run the full workflow (analyze, hotspots, explain, impact, snapshot, drift) in your repo for deterministic architecture insights.
Run ArcSight on your repo
Install the CLI and run analyze, then hotspots and explain for the same workflow.
This case study is generated from ArcSight analysis data. View short analysis. View all analyses