feat: v2 — config redesign, schema checks, and tooling modernization

[mwisner]

Summary

This is a major rework of the Cosmo Previews action, focused on three areas:

1. Config schema redesign

The cosmo.yaml format has been restructured for clarity and flexibility:

• Top-level subgraphs with typed support (standard, edfs, grpc) — only standard subgraphs can be previewed, but all types can be checked
• previews section replaces the flat feature_flags / subgraphs pairing — each preview has its own name, namespace, labels, and subgraph references with routing_url templates
• check section for multi-namespace schema checks
• Cross-validation via Zod .refine() ensures preview subgraph references point to existing standard subgraphs

Before (v1):

namespace: 'dev1'
feature_flags:
  - name: 'my-flag'
    labels:
      - 'graph=private'
subgraphs:
  - name: 'my-subgraph'
    schema_path: 'schema.graphqls'
    routing_url: 'http://my-svc-pr-${PR_NUMBER}.example.com/graphql'

After (v2):

version: '1'
subgraphs:
  - name: 'my-subgraph'
    schema_path: 'schema.graphqls'
  - name: 'events'
    type: edfs
    schema_path: 'events.graphqls'

previews:
  - name: 'my-preview'
    namespace: 'dev1'
    labels:
      - 'graph=private'
    subgraphs:
      - name: 'my-subgraph'
        routing_url: 'http://my-svc-pr-${PR_NUMBER}.example.com/graphql'

check:
  namespaces:
    - dev1
    - staging

2. Schema check support

New action: schema / stage: check mode that:

• Runs wgc subgraph check against all configured subgraphs across all namespaces in the check section
• Posts/updates a PR comment with a summary table (status, aggregated error/warning counts, Studio link)
• When issues exist, adds a collapsible <details> section per namespace/subgraph with full tables for:
  • Breaking changes
  • Composition errors/warnings
  • Lint errors/warnings
  • Graph pruning errors/warnings
• Uses --out flag for reliable JSON parsing (stdout from wgc -j outputs JS object notation, not valid JSON)

3. Tooling modernization

• pnpm replaces npm
• tsdown (rolldown-based) replaces ncc for bundling — single ESM output
• oxlint + oxfmt replace ESLint + Prettier
• vitest replaces jest
• lefthook for pre-commit hooks (format + lint)
• Node 24 runtime (using: node24 in action.yml)
• Zod v4 for all input/config validation with discriminated unions

4. Action input changes

The boolean create/update/destroy inputs are replaced with explicit action + stage:

action	stage	description
preview	create	Create feature flag + subgraphs
preview	update	Update feature subgraphs
preview	delete	Destroy feature flag + subgraphs
schema	check	Run schema checks and post PR comment

Breaking Changes

• Config format (cosmo.yaml) is completely different — see migration example above
• Action inputs changed from create/update/destroy booleans to action/stage strings
• cosmo_api_key and github_token are now required inputs
• Runtime changed from Node 20 to Node 24
• Bundle format changed from CJS (dist/index.js) to ESM (dist/index.mjs)
• wgc CLI is no longer bundled — must be installed in the workflow (npm i -g wgc@latest)

Test Plan

• Unit tests for config schema validation (12 tests)
• Unit tests for schema check output formatting (14 tests)
• Tested preview create/update/delete lifecycle on live repo
• Tested schema check with clean schema (all green, no details section)
• Tested schema check with breaking changes (error status, collapsible details with breaking change table)
• Tested schema check with lint warnings (warning counts in summary, lint table in details)

AI Disclosure

This pull request was developed with assistance from Claude Code (Claude Opus 4.6, Anthropic's AI coding assistant). Claude helped with:

• Code generation for the schema check implementation, config schema redesign, and test files
• Tooling migration (pnpm, tsdown, oxlint, vitest configuration)
• PR comment markdown formatting logic
• Writing this pull request description

All code was reviewed, tested, and validated by a human contributor. The architectural decisions (config schema design, preview abstraction, schema check behavior) were directed by the human author through iterative feedback.

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🤖 Generated with Claude Code