Playwright MCP Server

Instructions

Implementation Reference

• src/tools/codegen/index.ts:98-160 (handler)

  The core handler function that terminates the codegen session: ends the session via ActionRecorder, generates Playwright test code using PlaywrightGenerator, writes the test file to disk, and cleans up global browser/page instances.

  handler: async ({ sessionId }: { sessionId: string }) => {
    try {
      const recorder = ActionRecorder.getInstance();
      const session = recorder.endSession(sessionId);
  
      if (!session) {
        throw new Error(`Session ${sessionId} not found`);
      }
  
      if (!session.options) {
        throw new Error(`Session ${sessionId} has no options configured`);
      }
  
      const generator = new PlaywrightGenerator(session.options);
      const result = await generator.generateTest(session);
  
      // Double check output directory exists
      const outputDir = path.dirname(result.filePath);
      await fs.mkdir(outputDir, { recursive: true });
  
      // Write test file
      try {
        await fs.writeFile(result.filePath, result.testCode, "utf-8");
      } catch (writeError: any) {
        throw new Error(`Failed to write test file: ${writeError.message}`);
      }
  
      // Close Playwright browser and cleanup
      try {
        if (global.browser?.isConnected()) {
          await global.browser.close();
        }
      } catch (browserError: any) {
        console.warn("Failed to close browser:", browserError.message);
      } finally {
        global.browser = undefined;
        global.page = undefined;
      }
  
      const absolutePath = path.resolve(result.filePath);
  
      return {
        filePath: absolutePath,
        outputDirectory: outputDir,
        testCode: result.testCode,
        message: `Generated test file at: ${absolutePath}\nOutput directory: ${outputDir}`,
      };
    } catch (error: any) {
      // Ensure browser cleanup even on error
      try {
        if (global.browser?.isConnected()) {
          await global.browser.close();
        }
      } catch {
        // Ignore cleanup errors
      } finally {
        global.browser = undefined;
        global.page = undefined;
      }
  
      throw new Error(`Failed to end codegen session: ${error.message}`);
    }
  },

• src/tools/codegen/index.ts:88-97 (schema)

  Input schema definition for the end_codegen_session tool, specifying the required sessionId parameter.

  parameters: {
    type: "object",
    properties: {
      sessionId: {
        type: "string",
        description: "ID of the session to end",
      },
    },
    required: ["sessionId"],
  },

• src/toolHandler.ts:334-335 (registration)

  Registration in the main tool handler switch statement that dispatches calls to the endCodegenSession.handler function.

  case "end_codegen_session":
    return await handleCodegenResult(endCodegenSession.handler(args));

• src/tools.ts:37-49 (registration)

  Tool registration schema in createToolDefinitions() for MCP tool list, including name, description, and inputSchema.

    name: "end_codegen_session",
    description: "End a code generation session and generate the test file",
    inputSchema: {
      type: "object",
      properties: {
        sessionId: { 
          type: "string", 
          description: "ID of the session to end" 
        }
      },
      required: ["sessionId"]
    }
  },

• src/toolHandler.ts:584-609 (helper)

  Helper function used to wrap and format the result of codegen tool handlers, including end_codegen_session.

  async function handleCodegenResult(
    resultPromise: Promise<any>
  ): Promise<CallToolResult> {
    try {
      const result = await resultPromise;
      return {
        content: [
          {
            type: "text",
            text: JSON.stringify(result),
          },
        ],
        isError: false,
      };
    } catch (error) {
      return {
        content: [
          {
            type: "text",
            text: error instanceof Error ? error.message : String(error),
          },
        ],
        isError: true,
      };
    }
  }