How do you debug type-resolution and ESM/CJS mismatches with traceResolution and explain?

Question presented to candidate: "A teammate gets TS1479 importing an ESM-only package, and in another project the types compile but Node crashes with 'does not provide an export named default'. How would you use tsc --traceResolution and --explainFiles to find out what TypeScript actually resolved, and why?"

What a strong answer should cover:

• --traceResolution prints every module lookup: the mode (ESM or CJS), the conditions used (import/require, types, node), each exports condition matched or failed, every file tried and the final result
• --explainFiles prints why each file is in the program (include pattern, which import pulled it in) and, under node16/nodenext, whether each file is ESM or CommonJS and which package.json field decided it
• Reading TS1479: the importing file is CommonJS (no "type": "module"), the target is ESM; fixes are "type": "module", a .mts file or a dynamic import()
• Reading a fallback: when the matched condition has no declaration file, tsc tries later conditions, so it may type-check against a different file than Node loads (masquerading types)
• Practical workflow: redirect the output to a file and grep for the module name, --listFilesOnly and --showConfig for quick checks, and the attw tool for published packages

Clarifying questions expected:

• What is the moduleResolution setting, and is the importing package ESM or CommonJS?
• Is the problem a compile error, or code that compiles and fails at run time?

Code / implementation expected: Optional — the commands, and how to read the relevant trace lines.