feat(logging): add structured server diagnostics

packages/logging/package.json

@@ -0,0 +1,19 @@
+{
+  "name": "@minecraft-account-manager/logging",
+  "version": "0.1.0",
+  "private": true,
+  "type": "module",
+  "exports": { ".": "./src/index.ts" },
+  "scripts": {
+    "test": "vitest run",
+    "typecheck": "tsc --noEmit"
+  },
+  "dependencies": {
+    "pino": "^10.3.1"
+  },
+  "devDependencies": {
+    "@types/node": "^25.0.3",
+    "typescript": "^5.9.3",
+    "vitest": "^4.1.0"
+  }
+}

packages/logging/src/index.ts

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+import pino, { type DestinationStream, type Logger } from "pino";
+
+const redactedPaths = [
+  "apiKey",
+  "authorization",
+  "password",
+  "token",
+  "*.apiKey",
+  "*.authorization",
+  "*.password",
+  "*.token",
+  "headers.authorization",
+  "req.headers.authorization",
+];
+
+export function createLogger(
+  service: string,
+  options: { destination?: DestinationStream } = {},
+): Logger {
+  return pino(
+    {
+      level: process.env.LOG_LEVEL?.trim() || "info",
+      base: {
+        service,
+        environment: process.env.NODE_ENV ?? "development",
+        version: process.env.APP_VERSION ?? "development",
+      },
+      redact: {
+        paths: redactedPaths,
+        censor: "[Redacted]",
+      },
+    },
+    options.destination,
+  );
+}

packages/logging/test/logger.test.ts

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+import { Writable } from "node:stream";
+import { describe, expect, it } from "vitest";
+import { createLogger } from "../src/index";
+
+function captureLog() {
+  let output = "";
+  const destination = new Writable({
+    write(chunk, _encoding, callback) {
+      output += chunk.toString();
+      callback();
+    },
+  });
+  return { destination, read: () => JSON.parse(output.trim()) as Record<string, unknown> };
+}
+
+describe("structured application logging", () => {
+  it("emits service metadata and redacts credential fields", () => {
+    const capture = captureLog();
+    const logger = createLogger("account-manager-test", { destination: capture.destination });
+
+    logger.info({ token: "secret-token", apiKey: "secret-key", operation: "test" }, "Test event");
+
+    expect(capture.read()).toMatchObject({
+      service: "account-manager-test",
+      token: "[Redacted]",
+      apiKey: "[Redacted]",
+      operation: "test",
+      msg: "Test event",
+    });
+  });
+});

packages/logging/tsconfig.json

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+{
+  "extends": "../../tsconfig.base.json",
+  "compilerOptions": { "types": ["node", "vitest/globals"] },
+  "include": ["src/**/*.ts", "test/**/*.ts"]
+}