LSP-Enhanced Analysis

Claude Code provides built-in LSP (Language Server Protocol) tools that give you semantic code understanding — actual dependency graphs instead of text pattern matching. When LSP is available, use it. When it's not, fall back to grep/glob silently.

This skill applies to any agent that performs code analysis — coupling, test coverage, architecture boundaries, migration scoping, or structural understanding.

LSP Operations

Operation	What it does	Use it for
`find-references`	Find all usages of a symbol across the workspace	Dependency mapping, counting consumers of exports, detecting cross-boundary calls
`call-hierarchy` (incoming)	Find all functions that call the target function	Afferent coupling — who depends on this? Blast radius of a change
`call-hierarchy` (outgoing)	Find all functions the target function calls	Efferent coupling — what does this depend on? Transitive dependency depth
`go-to-definition`	Jump to where a symbol is defined	Resolving what an imported symbol actually is, following re-exports
`hover`	Get type information and documentation for a symbol	Type info for complexity assessment, understanding interfaces without reading source
`document-symbols`	List all symbols in a file (functions, classes, interfaces)	Module structure overview, listing exports, quick structural scan
`workspace-symbols`	Search for symbols by name across the entire workspace	Finding types, interfaces, or classes by name across the codebase

Graph Reasoning

LSP responses are graph edges, not search results. Each find-references call returns edges in a dependency graph. Each call-hierarchy call returns paths through that graph. Build the graph, then reason over it.

Transitivity. Don't stop at direct callers or callees. Use call-hierarchy to follow chains. If A calls B and B calls C, then A depends on C. Grep only shows you A→B and B→C as separate matches — LSP gives you the chain directly.

Completeness. find-references returns ALL usages, not a sample. Count them. "3 callers" vs "47 callers" is the difference between loosely coupled and tightly coupled. Grep misses re-exports, aliased imports, inherited methods, and framework-injected references.

Quantify coupling with fan-in and fan-out.

Fan-in = incomingCalls count. How many things depend on this symbol? High fan-in means changes here propagate widely.
Fan-out = outgoingCalls count. How many things does this symbol depend on? High fan-out means this is fragile — many reasons for it to break.

Blast radius = incomingCalls depth. How far does a change propagate through the call graph? A function with 3 direct callers might have 50 transitive dependents.

Testability = outgoingCalls depth. How many things must be mocked or stubbed to test this in isolation? A function with 1 import but 15 transitive outgoing calls is not a low-hanging fruit for unit testing.

Why this matters more than grep. Grep finds text matches. LSP finds semantic connections. Grep misses:

Re-exported symbols used under a different name
Inherited methods called on a subclass
Framework-injected dependencies (decorators, annotations, DI containers)
Dynamic dispatch through interfaces or abstract classes

When you have LSP data, reason over the graph structure. When you don't, acknowledge that grep-based analysis is an approximation.

Availability Check

Check LSP availability once at the start of your analysis, not per-operation.

Early in your analysis, attempt document-symbols on one of the target files.
If it returns symbols: LSP is available. Use LSP operations for the rest of your analysis.
If it fails or returns nothing: LSP is not available. Use grep/glob for all analysis steps.

Decide once. Don't retry LSP after it fails — repeated failures waste time and add noise. Set a flag and move on.

Graceful Degradation

When LSP is not available:

Do not error. Do not warn during analysis. Fall back silently to grep/glob — the same analysis the agent did before LSP existed.
Every LSP-enhanced step must have a grep fallback. If the agent used find-references for dependency mapping, the fallback is Grep for import/require patterns. If it used call-hierarchy for coupling depth, the fallback is reading files and tracing calls manually.
Note at the end of output. After the analysis is complete, add: "Note: LSP was not available for this analysis. Results use text-based pattern matching. For more accurate dependency analysis, consider configuring a language server — see the language server reference table below."
Reference the language table so the developer knows which server to explore for their ecosystem.

Output Signaling

Include one of these phrases in your analysis output so the developer knows the confidence level:

When LSP was used: "Analysis method: LSP-enhanced analysis"
When LSP was not available: "Analysis method: text-based pattern matching"

Place this near the top of the output, before the findings. This is a single line — not a paragraph, not a disclaimer.

Language Server Reference

Language	LSP Server
TypeScript / JavaScript	typescript-language-server
Java	jdtls (Eclipse JDT Language Server)
Go	gopls
Python	pyright
Rust	rust-analyzer
C / C++	clangd
Ruby	solargraph
C#	omnisharp
Kotlin	kotlin-language-server
PHP	intelephense
Swift	sourcekit-lsp

lsp-analysis