Implement DID Document Validation Logic

[chrishooooo-netizen]

Summary

Build a validation module that checks whether a did:trail DID Document conforms to the TRAIL DID Method specification. This is a core building block for any resolver or verifier implementation.

What needs to happen

1. Create validation/did-document-validator.js with functions that validate:

   • Required top-level fields (id, controller, verificationMethod, authentication)
   • id format matches did:trail:<namespace>:<unique-id> pattern
   • verificationMethod entries have valid type, controller, and key material (publicKeyJwk or publicKeyMultibase)
   • Service endpoints (if present) have valid id, type, and serviceEndpoint
   • Capability delegation chain structure (delegator → delegate relationship)

2. Create test fixtures in validation/fixtures/:

   • valid-did-document.json — a fully conformant DID Document
   • invalid-*.json — documents with specific violations (missing fields, wrong key format, malformed ID, etc.)

3. Create validation/validate.js — a CLI runner that takes a DID Document JSON file and outputs validation results

4. Add a README.md in validation/ explaining usage and linking to the relevant spec sections

Acceptance criteria

• Validator catches all required-field violations
• Validator accepts a fully conformant document without false positives
• At least 5 test fixtures covering different error cases
• CLI runner works: node validation/validate.js fixtures/valid-did-document.json
• Code follows the style established in examples/js/

Context

• DID Method Spec: see spec/did-trail-method.md in this repo
• Builds on the JS examples from Good First Issue: Add DID Resolution Examples #4 / PR Improve JS examples and add HTTP DID resolution example #5
• This directly supports future resolver and verifier implementations

Labels

help wanted · enhancement

cc @AmeyParle — this follows up on your interest in contributing to core validation logic (see your comment on #4). Would love to have you take this on!

[AmeyParle]

Thanks a lot — I’d love to take this on.

I’ll start by extracting the validation rules from the spec and then put together the validator, fixtures, and CLI runner. I may ask a few clarification questions as I work through the DID Document requirements.

Excited to contribute!!

[AmeyParle]

I’ve opened a draft PR for #6 with the validator, fixtures, CLI runner, and validation README. Happy to adjust anything based on feedback.