Ctags Usage

Ctags Usage for Efficient Code Navigation

Overview

This plugin maintains a ctags index at .claude/tags that maps symbol names to their locations. The index includes both definitions and references, making it useful for finding where symbols are defined AND where they are used. Use this index for efficient code navigation with minimal token usage instead of running broad grep or tree searches.

When to Use Ctags

Use ctags lookup FIRST when:

• Finding where a class, function, method, or type is defined
• Finding references to a symbol (where it's used, imported, called)
• Navigating to a symbol's source location
• The user asks "where is X defined?" or "find references to X"

Fall back to grep when:

• Searching for text patterns that aren't symbol names
• Searching for string literals, comments, or documentation
• The ctags lookup returns no results
• Searching in file types not indexed by ctags

How to Query the Tags Index

Direct Tags File Query

Query the tags file using grep for the symbol name:

grep "^SymbolName	" .claude/tags

The tags file format is tab-separated:

symbol_name<TAB>file_path<TAB>pattern_or_line<TAB>kind

Using the Query Script

For cleaner output with file:line format:

bash ${CLAUDE_PLUGIN_ROOT}/scripts/query-tags.sh SymbolName

Returns results like:

src/services/user.ts:42
src/models/user.ts:15

Interpreting Results

• Multiple results indicate the symbol appears in multiple places (definitions AND references)
• Use the kind field to distinguish:
  • c = class, f = function, m = method, v = variable (definitions)
  • r = reference (where the symbol is used/imported/called)
• Filter by kind to narrow results: grep "^Symbol\t" .claude/tags | grep "kind:r" for references only
• Read the specific file at the returned line number

Token Efficiency Strategy

Before (Inefficient)

User: "Where is UserService defined?"

Step 1: grep -r "UserService" .
Result: 50 lines (imports, usages, comments, definition)
Tokens: ~2000

Step 2: Read several files to find the actual definition
Tokens: ~3000 more

Total: ~5000 tokens

After (Efficient with Ctags)

User: "Where is UserService defined?"

Step 1: grep "^UserService	" .claude/tags
Result: src/services/user.ts:42 (1 line)
Tokens: ~20

Step 2: Read src/services/user.ts at line 42
Tokens: ~500

Total: ~520 tokens (90% reduction)

Index Management

Automatic Updates

The tags index automatically regenerates:

• On session start
• After any Edit or Write tool use
• Before git commit commands

Manual Refresh

If the index seems stale, use the refresh command:

/claude-ctags:refresh

Or run directly:

bash ${CLAUDE_PLUGIN_ROOT}/scripts/regenerate-tags.sh

Index Location

• Tags file: .claude/tags
• Added to .gitignore automatically

Supported Languages

Universal Ctags supports 100+ languages including:

• JavaScript/TypeScript
• Python
• Go
• Rust
• Java
• C/C++
• Ruby
• PHP
• And many more

Check language support:

ctags --list-languages

Workflow Integration

Finding Definitions

1. Receive query about symbol location
2. Query ctags index first
3. If found, read the specific file at that line
4. If not found, fall back to grep

Code Navigation

When exploring unfamiliar code:

1. Identify key symbol names from context
2. Use ctags to jump directly to definitions
3. Avoid scanning entire directories with tree or find

Before Code Changes

When about to modify code:

1. Use ctags to locate the exact definition
2. Understand the implementation before changing
3. Index updates automatically after edits

Limitations

• Language support: Some languages have limited tag extraction
• Dynamic code: Runtime-generated symbols not indexed
• Freshness: Index may lag briefly after rapid edits
• Reference coverage: Not all references may be captured depending on language

For patterns not captured by ctags, fall back to grep:

grep -r "SymbolName" --include="*.ts" .

Quick Reference

Best Practices

1. Query ctags first for definition lookups
2. Read the specific line returned, not the whole file
3. Use grep for references when ctags is inappropriate
4. Trust the auto-refresh - manual refresh rarely needed
5. Check symbol kind when multiple results returned

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