extract stream parser module with tests, add mcp tool call logging

Co-Authored-By: Claude Opus 4.6 <noreply@anthropic.com>

src/servers/mcp-tool-server.ts

@@ -13,8 +13,8 @@
 import { McpServer } from '@modelcontextprotocol/sdk/server/mcp.js';
 import { StdioServerTransport } from '@modelcontextprotocol/sdk/server/stdio.js';
 import { z } from 'zod';
-import { readdirSync, existsSync, readFileSync } from 'node:fs';
-import { join } from 'node:path';
+import { readdirSync, existsSync, readFileSync, appendFileSync, mkdirSync } from 'node:fs';
+import { join, dirname } from 'node:path';
 
 // ── Types ──
 
@@ -186,6 +186,31 @@ function buildZodSchema(inputs: Record<string, ToolParam>): z.ZodRawShape {
   return shape;
 }
 
+// ── Logging ──
+
+const LOG_FILE = process.env.MCP_TOOLS_LOG ?? '';
+
+function logToolCall(toolName: string, durationMs: number, success: boolean, error?: string): void {
+  const ts = new Date().toISOString();
+  const status = success ? 'ok' : 'error';
+  const line = error
+    ? `${ts}\t${toolName}\t${status}\t${durationMs}ms\t${error}\n`
+    : `${ts}\t${toolName}\t${status}\t${durationMs}ms\n`;
+
+  // Always log to stderr for process-level visibility
+  console.error(`[mcp-tools] ${toolName} ${status} (${durationMs}ms)${error ? ': ' + error : ''}`);
+
+  // Write to log file if configured
+  if (LOG_FILE) {
+    try {
+      mkdirSync(dirname(LOG_FILE), { recursive: true });
+      appendFileSync(LOG_FILE, line);
+    } catch {
+      // Don't fail tool calls over logging
+    }
+  }
+}
+
 // ── Main ──
 
 const rawDirs = process.env.PI_TOOLS_DIRS ?? '';
@@ -218,11 +243,14 @@ for (const { entryFile, meta } of tools) {
       inputSchema: z.object(schema),
     },
     async (params) => {
+      const start = performance.now();
       let executeFn: Function | undefined;
       try {
         const mod = await import(capturedEntry);
         executeFn = mod.execute ?? mod.default?.execute;
       } catch (err) {
+        const ms = Math.round(performance.now() - start);
+        logToolCall(toolName, ms, false, `load failed: ${String(err)}`);
         return {
           content: [{ type: 'text' as const, text: `Failed to load ${toolName}: ${String(err)}` }],
           isError: true,
@@ -230,14 +258,27 @@ for (const { entryFile, meta } of tools) {
       }
 
       if (typeof executeFn !== 'function') {
+        const ms = Math.round(performance.now() - start);
+        logToolCall(toolName, ms, false, 'no execute function');
         return {
           content: [{ type: 'text' as const, text: `${toolName}/index.ts must export an "execute" function` }],
           isError: true,
         };
       }
 
-      const result = await executeFn('mcp', params, undefined, undefined);
-      return result;
+      try {
+        const result = await executeFn('mcp', params, undefined, undefined);
+        const ms = Math.round(performance.now() - start);
+        logToolCall(toolName, ms, !result.isError, result.isError ? 'tool returned error' : undefined);
+        return result;
+      } catch (err) {
+        const ms = Math.round(performance.now() - start);
+        logToolCall(toolName, ms, false, String(err));
+        return {
+          content: [{ type: 'text' as const, text: `${toolName} threw: ${String(err)}` }],
+          isError: true,
+        };
+      }
     },
   );