lsp-client/lsp-skill/lsp-code-analysis

LSP Code Analysis

IMPORTANT: PREREQUISITE

To use this skill, you MUST follow these steps:

1. Check for updates: Run the update script to ensure you are using the latest version of the tool.
2. Verify project support: Run lsp server start <project_path> to start the LSP server and confirm the project is supported.

IF YOU DO NOT PERFORM THESE STEPS, YOU ARE NOT ALLOWED TO USE THIS SKILL.

Abstract

This document specifies the operational requirements and best practices for the lsp-code-analysis skill. It provides a semantic interface to codebase navigation, analysis and refactoring via the Language Server Protocol (LSP).

Overview

You are provided with lsp CLI tool for semantic code navigation and analysis. It SHOULD be preferred over read or grep for most code understanding tasks.

Usages:

• Semantic navigation: Jump to definitions, find references, locate implementations - understands code structure, not just text patterns.
• Language-aware: Distinguishes between variables, functions, classes, types - eliminates false positives from text search.
• Cross-file intelligence: Trace dependencies, refactor safely across entire codebase - knows what imports what.
• Type-aware: Get precise type information, signatures, documentation - without reading implementation code.

Tool Selection

Guideline: You SHOULD prioritize LSP commands for code navigation and analysis. Agents MAY use read or grep ONLY when semantic analysis is not applicable (e.g., searching for comments or literal strings).

Commands

All commands support -h or --help.

Locating Symbols

Most commands use a unified locating syntax via the --scope and --find options.

Arguments: <file_path>

Options:

• --scope: Narrow search to a symbol body or line range.
• --find: Text pattern to find within the scope.

Scope Formats:

• <line>: Single line number (e.g., 42).
• <start>,<end>: Line range (e.g., 10,20). Use 0 for end to mean till EOF (e.g., 10,0).
• <symbol_path>: Symbol path with dots (e.g., MyClass.my_method).

Find Pattern (`--find`):

The --find option narrows the target to a text pattern within the selected scope:

• The scope is determined by --scope (line/range/symbol). If no --scope is given, the entire file is the scope.
• Pattern matching is whitespace-insensitive: differences in spaces, tabs, and newlines are ignored.
• You MAY include the cursor marker <|> inside the pattern to specify the exact position of interest within the match (for example, on a variable name, keyword, or operator).
• If --find is omitted, the command uses the start of the scope (or a tool-specific default) as the navigation target.

Cursor Marker (`<|>`):

The <|> marker indicates the exact position for symbol resolution. It represents the character immediately to its right. Use it within the find pattern to point to a specific element (e.g., user.<|>name to target the name property).

Examples:

• lsp doc foo.py --find "self.<|>" - Find self. in entire file, position at the character after the dot (typically for completion or member access)
• lsp doc foo.py --scope 42 --find "return <|>result" - Find return result on line 42, position at r of result
• lsp doc foo.py --scope 10,20 --find "if <|>condition" - Find if condition in lines 10-20, position at c of condition
• lsp doc foo.py --scope MyClass.my_method --find "self.<|>" - Find self. within MyClass.my_method, position after the dot
• lsp doc foo.py --scope MyClass - Target the MyClass symbol directly

Guideline for Scope vs. Find:

• Use --scope <symbol_path> (e.g., --scope MyClass, --scope MyClass.my_method) to target classes, functions, or methods. This is the most robust and preferred way to target symbol.
• Use --find (often combined with --scope) to target variables or specific positions. Use this when the target is not a uniquely named symbol or when you need to pinpoint a specific usage within a code block.

Agents MAY use lsp locate <file_path> --scope <scope> --find <find> to verify if the target exists in the file and view its context before running other commands.

# Verify location exists
lsp locate main.py --scope 42 --find "<|>process_data"

Pagination

Use pagination for large result sets like reference or search.

• --pagination-id <ID>: (Required) Unique session ID for consistent paging.
• --max-items <N>: Page size.
• --start-index <N>: Offset (0-based).

Example:

# Page 1
lsp search "User" --max-items 20 --pagination-id "task_123"
 
# Page 2
lsp search "User" --max-items 20 --start-index 20 --pagination-id "task_123"

Guideline: Use pagination with a unique ID for common symbols to fetch results in manageable chunks. Increment --start-index using the same ID to browse.

Outline: File Structure

Get hierarchical symbol structure without reading implementation.

# Get main symbols (classes, functions, methods)
lsp outline <file_path>
 
# Get all symbols including variables and parameters
lsp outline <file_path> --all

Agents SHOULD use outline before reading files to avoid unnecessary context consumption.

Definition: Navigate to Source

Navigate to where symbols are defined.

# Jump to where User.get_id is defined
lsp definition models.py --scope User.get_id
 
# Find where an imported variable comes from
lsp definition main.py --scope 42 --find "<|>config"
 
# Find declaration (e.g., header files, interface declarations)
lsp definition models.py --scope 25 --mode declaration --find "<|>provider"
 
# Find the class definition of a variable's type
lsp definition models.py --scope 30 --find "<|>user" --mode type_definition

Reference: Find All Usages

Find where symbols are used or implemented.

# Find all places where logger is referenced
lsp reference main.py --scope MyClass.run --find "<|>logger"
 
# Find all concrete implementations of an interface/abstract class
lsp reference api.py --scope "IDataProvider" --mode implementations
 
# Get more surrounding code context for each reference
lsp reference app.py --scope 10 --find "<|>my_var" --context-lines 5
 
# Limit results for large codebases
lsp reference utils.py --find "<|>helper" --max-items 50 --start-index 0

Doc: Get Documentation

Get documentation and type information without navigating to source.

# Get docstring and type info for symbol at line 42
lsp doc main.py --scope 42
 
# Get API documentation for process_data function
lsp doc models.py --scope process_data

Agents SHOULD prefer doc over read when only documentation or type information is needed.

Search: Global Symbol Search

Search for symbols across the workspace when location is unknown.

# Search by name (defaults to current directory)
lsp search "MyClassName"
 
# Search in specific project
lsp search "UserModel" --project /path/to/project
 
# Filter by symbol kind (can specify multiple times)
lsp search "init" --kinds function --kinds method
 
# Limit and paginate results for large codebases
lsp search "Config" --max-items 10
lsp search "User" --max-items 20 --start-index 0

Agents SHOULD use --kinds to filter results and reduce noise.

Symbol: Get Complete Symbol Code

Get the full source code of the symbol containing a location.

# Get complete code of the function/class at line 15
lsp symbol main.py --scope 15
 
# Get full UserClass implementation
lsp symbol utils.py --scope UserClass
 
# Get complete method implementation
lsp symbol models.py --scope User.validate

Response includes: symbol name, kind (class/function/method), range, and complete source code.

Agents SHOULD use symbol to read targeted code blocks instead of using read on entire files.

Refactoring Operations

Read Refactoring Guide for rename, extract, and other safe refactoring operations.

Server: Manage Background Servers

The background manager starts automatically. Manual control is OPTIONAL.

# List running servers
lsp server list
 
# Start server for a project
lsp server start <path>
 
# Stop server for a project
lsp server stop <path>
 
# Shutdown the background manager
lsp server shutdown

Best Practices

General Workflows

Understanding Unfamiliar Code

The RECOMMENDED sequence for exploring new codebases:

# Step 1: Start with outline - Get file structure without reading implementation
lsp outline <file_path>
 
# Step 2: Inspect signatures - Use doc to understand API contracts
lsp doc <file_path> --scope <symbol_name>
 
# Step 3: Navigate dependencies - Follow definition chains
lsp definition <file_path> --scope <symbol_name>
 
# Step 4: Map usage - Find where code is called with reference
lsp reference <file_path> --scope <symbol_name>

Debugging Unknown Behavior

# Step 1: Locate symbol definition workspace-wide
lsp search "<symbol_name>"
 
# Step 2: Verify implementation details
lsp definition <file_path> --scope <symbol_name>
 
# Step 3: Trace all callers to understand invocation context
lsp reference <file_path> --scope <symbol_name>

Finding Interface Implementations

# Step 1: Locate interface definition
lsp search "IUserService" --kinds interface
 
# Step 2: Find all implementations
lsp reference src/interfaces.py --scope IUserService --mode implementations

Tracing Data Flow

# Step 1: Find where data is created
lsp search UserDTO --kinds class
 
# Step 2: Find where it's used
lsp reference models.py --scope UserDTO
 
# Step 3: Check transformations
lsp doc transform.py --scope map_to_dto

Understanding Type Hierarchies

# Step 1: Get class outline
lsp outline models.py
 
# Step 2: Find subclasses (references to base)
lsp reference models.py --scope BaseModel
 
# Step 3: Check type definitions
lsp definition models.py --scope BaseModel --mode type_definition

Performance Tips

# Use outline instead of reading entire files
lsp outline large_file.py  # Better than: read large_file.py
 
# Use symbol paths for nested structures (more precise than line numbers)
lsp definition models.py --scope User.Profile.validate
 
# Limit results in large codebases
lsp search "User" --max-items 20
 
# Use doc to understand APIs without navigating to source
lsp doc api.py --scope fetch_data  # Get docs/types without jumping to definition
 
# Verify locate strings if commands fail
lsp locate main.py --scope 42 --find "<|>my_var"

Domain-Specific Guides

For specialized scenarios, see:

• Monorepo: monorepo.md
• Frontend: bp_frontend.md
• Backend: bp_backend.md