Context+

Instructions

Implementation Reference

• src/tools/blast-radius.ts:20-73 (handler)

  The main implementation of the getBlastRadius function.

  export async function getBlastRadius(options: BlastRadiusOptions): Promise<string> {
    const entries = await walkDirectory({ rootDir: options.rootDir, depthLimit: 0 });
    const files = entries.filter((e) => !e.isDirectory && isSupportedFile(e.path));
    const usages: SymbolUsage[] = [];
    const symbolPattern = new RegExp(`\\b${escapeRegex(options.symbolName)}\\b`, "g");
  
    for (const file of files) {
      try {
        const content = await readFile(file.path, "utf-8");
        const lines = content.split("\n");
  
        for (let i = 0; i < lines.length; i++) {
          if (symbolPattern.test(lines[i])) {
            const isDefinition = options.fileContext && file.relativePath === options.fileContext && isDefinitionLine(lines[i], options.symbolName);
            if (!isDefinition) {
              usages.push({
                file: file.relativePath,
                line: i + 1,
                context: lines[i].trim().substring(0, 120),
              });
            }
            symbolPattern.lastIndex = 0;
          }
        }
      } catch {
      }
    }
  
    if (usages.length === 0) return `Symbol "${options.symbolName}" is not used anywhere in the codebase.`;
  
    const byFile = new Map<string, SymbolUsage[]>();
    for (const u of usages) {
      const existing = byFile.get(u.file) ?? [];
      existing.push(u);
      byFile.set(u.file, existing);
    }
  
    const lines: string[] = [
      `Blast radius for "${options.symbolName}": ${usages.length} usages in ${byFile.size} files\n`,
    ];
  
    for (const [file, fileUsages] of byFile) {
      lines.push(`  ${file}:`);
      for (const u of fileUsages) {
        lines.push(`    L${u.line}: ${u.context}`);
      }
    }
  
    if (usages.length <= 1) {
      lines.push(`\n⚠ LOW USAGE: This symbol is used only ${usages.length} time(s). Consider inlining if it's under 20 lines.`);
    }
  
    return lines.join("\n");
  }

• src/tools/blast-radius.ts:8-12 (schema)

  The interface defining the input parameters for the getBlastRadius tool.

  export interface BlastRadiusOptions {
    rootDir: string;
    symbolName: string;
    fileContext?: string;
  }

• src/index.ts:281-291 (registration)

  The tool registration and invocation logic in the main MCP handler.

  "get_blast_radius",
  "Before deleting or modifying code, check the BLAST RADIUS. Traces every file and line where a specific symbol " +
  "(function, class, variable) is imported or used. Prevents orphaned code. Also warns if usage count is low (candidate for inlining).",
  {
    symbol_name: z.string().describe("The function, class, or variable name to trace across the codebase."),
    file_context: z.string().optional().describe("The file where the symbol is defined. Excludes the definition line from results."),
  },
  withRequestActivity(async ({ symbol_name, file_context }) => ({
    content: [{
      type: "text" as const,
      text: await getBlastRadius({ rootDir: ROOT_DIR, symbolName: symbol_name, fileContext: file_context }),