[plan] Add test coverage for goccy/go-yaml edge cases (empty sequences, nested anchors)

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Objective

Add test cases for edge cases fixed in recent goccy/go-yaml commits to ensure gh-aw workflows don't hit these subtle parser bugs.

Context

From issue #16054, two bugs were fixed TODAY (2026-02-16) in goccy/go-yaml:

1. Fix empty sequence item consuming sibling mapping key (Fix: Ensure localhost domains are always included in Playwright allowed_domains #850)
2. Fix sibling anchor aliases silently resolving to nil (Update Playwright MCP configuration to use Docker instead of npx #848)

These fixes show the library is responsive to bugs, but we should add tests to ensure gh-aw doesn't hit these edge cases.

Approach

1. Review the bug fix PRs in goccy/go-yaml (Fix: Ensure localhost domains are always included in Playwright allowed_domains #850, Update Playwright MCP configuration to use Docker instead of npx #848) to understand the failure scenarios
2. Create test cases that exercise these edge cases in gh-aw's context
3. Focus on workflow files that use anchors or empty sequences
4. Add tests to existing test files or create new ones

Areas to Test

• Empty sequences followed by mapping keys
• Nested anchor references
• Context map mutations in anchor resolution
• Complex YAML structures with anchors and aliases

Files to Modify

• pkg/parser/yaml_error_test.go - Add edge case tests
• pkg/workflow/compiler_test.go - Test workflow compilation with edge cases
• Consider creating: pkg/parser/yaml_edge_cases_test.go

Acceptance Criteria

• Tests cover empty sequence edge case (bug Fix: Ensure localhost domains are always included in Playwright allowed_domains #850)
• Tests cover anchor alias edge case (bug Update Playwright MCP configuration to use Docker instead of npx #848)
• Tests pass with current version of goccy/go-yaml
• Tests are documented with references to upstream bugs
  Related to [go-fan] Go Module Review: goccy/go-yaml #16054

Generated by Plan Command for issue #16054

• expires on Feb 18, 2026, 10:02 AM UTC