Stimulus Docs MCP Server

Instructions

Implementation Reference

• src/index.ts:21-43 (handler)

  The async handler function executed when the 'reference-targets' tool is called. It reads the specific markdown file ('reference/targets.md') via readMarkdownFile and returns the content as an MCP text block, with error handling.
  async () => { try { const content = await readMarkdownFile(path.join(folder, file)); return { content: [ { type: "text", text: content } ] }; } catch (error) { const errorMessage = error instanceof Error ? error.message : String(error); return { content: [ { type: "text", text: `Error reading ${file}: ${errorMessage}` } ] }; } }
• src/index.ts:17-45 (registration)

  Registration loop that creates the 'reference-targets' tool (and others) using MCP server.tool(name, description, handler), with name and file from config.
  docFiles.forEach(({ folder, file, name, description }) => { server.tool( name, description, async () => { try { const content = await readMarkdownFile(path.join(folder, file)); return { content: [ { type: "text", text: content } ] }; } catch (error) { const errorMessage = error instanceof Error ? error.message : String(error); return { content: [ { type: "text", text: `Error reading ${file}: ${errorMessage}` } ] }; } } ); });
• src/config.ts:91-94 (registration)

  Configuration entry in docFiles array that defines the name 'reference-targets', description, and source file path for the tool.
  folder: 'reference', file: 'targets.md', name: 'reference-targets', description: 'Targets API reference - covers target definitions, properties (singular/plural/existential), shared targets, optional targets, and target lifecycle callbacks' },
• src/documentReader.ts:14-61 (helper)

  Core helper function readMarkdownFile that implements file fetching logic (cache, GitHub API/raw, local fallback) for the documentation markdown files, called by the tool handler.
  export async function readMarkdownFile(filename: string): Promise<string> { const filePath = path.join(docsFolder, filename); if (!filePath.startsWith(docsFolder)) { throw new Error("Invalid file path"); } // Get current commit info if we don't have it yet if (!mainBranchInfo) { try { const commitInfo = await fetchMainBranchInformation(); const cacheKey = `${commitInfo.sha.substring(0, 7)}-${commitInfo.timestamp}`; mainBranchInfo = { ...commitInfo, cacheKey }; } catch (shaError) { console.error('Failed to get GitHub commit info, falling back to direct fetch'); } } // Try to read from cache first if we have commit info if (mainBranchInfo) { const cachedFilePath = path.join(cacheFolder, mainBranchInfo.cacheKey, filename); try { const content = await fs.promises.readFile(cachedFilePath, "utf-8"); console.error(`Using cached content for ${mainBranchInfo.cacheKey}: ${filename}`); return content; } catch (cacheError) { // Cache miss, continue to fetch from GitHub } } // Fetch from GitHub try { return await fetchFromGitHub(filename, mainBranchInfo?.cacheKey); } catch (githubError) { console.error(`GitHub fetch failed: ${githubError}, attempting to read from local files...`); // Fallback: read from local files try { return await fs.promises.readFile(filePath, "utf-8"); } catch (localError) { const githubErrorMessage = githubError instanceof Error ? githubError.message : String(githubError); const localErrorMessage = localError instanceof Error ? localError.message : String(localError); throw new Error(`Failed to read file from GitHub (${githubErrorMessage}) and locally (${localErrorMessage})`); } } }
• src/utils.ts:50-74 (helper)

  Utility function fetchFromGitHub used by readMarkdownFile to retrieve latest markdown content from the stimulus-site GitHub repo and cache it.
  export async function fetchFromGitHub(filename: string, cacheKey?: string): Promise<string> { const githubUrl = `${GITHUB_RAW_BASE_URL}/${filename}`; const response = await fetch(githubUrl); if (!response.ok) { throw new Error(`GitHub fetch failed: ${response.status} ${response.statusText}`); } const content = await response.text(); // Cache the content with cache key if available if (cacheKey) { try { const cacheFolder = path.resolve(__dirname, "../cache"); const cachedFilePath = path.join(cacheFolder, cacheKey, filename); await fs.promises.mkdir(path.dirname(cachedFilePath), { recursive: true }); await fs.promises.writeFile(cachedFilePath, content, "utf-8"); console.error(`Cached GitHub content for ${cacheKey}: ${filename}`); } catch (cacheError) { console.error(`Failed to cache content: ${cacheError}`); } } return content; }