Tools

stellarion_analyze_coupling [Pro]

Measure module coupling with afferent, efferent, and instability metrics

This is a Pro tool. Requires a Stellarion Pro license. A 180-day free trial starts automatically.

Computes module coupling metrics using the indexed dependency graph. Measures afferent coupling (incoming dependencies), efferent coupling (outgoing dependencies), and instability ratio. Uses existing graph edges — no re-parsing required.

When to Use

Before refactoring to identify tightly coupled modules
To find modules that are too dependent on external code (high instability)
To locate stable core modules that many others depend on
When planning module boundaries or extracting packages

Parameters

Parameter	Type	Required	Default	Description
`uri`	string	Yes	—	File or directory path to analyze
`includeExternal`	boolean	No	`false`	Include external/third-party dependencies in the analysis
`depth`	number	No	`2`	How many levels of transitive dependencies to follow
`summary`	boolean	No	`false`	Return a condensed summary instead of full breakdown

Examples

Analyze a specific module

What's the coupling profile for src/services/auth/?

Returns afferent/efferent counts and instability for the auth service module.

Find the most coupled modules in the project

Show me coupling metrics for the entire src/ directory with a summary.

Uses summary: true to get a ranked overview of all modules by coupling.

Include third-party dependencies

Analyze coupling for src/api/ including external dependencies. I want to see how much we depend on third-party packages.

Sets includeExternal: true to include imports from node_modules, crates.io dependencies, pip packages, etc.

Deep transitive analysis

Show coupling for src/core/engine.rs with depth 3. I want to see the full dependency chain.

Follows dependencies three levels deep to reveal hidden transitive coupling.

Output Format

For each module analyzed:

Afferent coupling (Ca) — number of modules that depend on this module
Efferent coupling (Ce) — number of modules this module depends on
Instability (I) — ratio Ce / (Ca + Ce), ranging from 0.0 (maximally stable) to 1.0 (maximally unstable)
Dependency list — which modules are incoming and outgoing

Instability interpretation:

Score	Meaning
0.0	Fully stable — many depend on it, it depends on nothing
0.0–0.3	Stable — changing it affects many consumers
0.3–0.7	Balanced
0.7–1.0	Unstable — depends on many, few depend on it
1.0	Fully unstable — depends on others, nobody depends on it

Tips

Stable modules (low instability) should contain abstractions and interfaces — they are hard to change
Unstable modules should contain concrete implementations — they are easy to change
A module with high afferent coupling AND high efferent coupling is a risk: it is both hard to change and has many reasons to change
Use depth: 1 for a quick overview, increase to 3 or more when investigating specific dependency chains
Pair with stellarion_codebase_health to see coupling in the context of overall project health

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Scan codebase for security vulnerabilities and unsafe patterns

stellarion_find_unused_code [Pro]

Detect dead code with confidence scoring and framework-aware heuristics