Refactor inline skill/sub-agent extraction to shared parser helpers

[Copilot]

The issue identified near-clone parser implementations for inline skills and inline sub-agents, creating avoidable duplication and drift risk in core markdown section parsing. This PR addresses the highest-impact low-risk refactor by consolidating shared extraction mechanics while preserving existing public behavior.

• What changed

  • Added shared internal helpers in pkg/parser/inline_section_helpers.go for:
    • H2 boundary discovery
    • inline section slicing (name + content)
    • duplicate-name detection
  • Refactored both extractors to use shared logic:
    • inline_skill_extractor.go
    • sub_agent_extractor.go
  • Moved GetEngineSkillDir and GetEngineSubAgentDir from the parser package to pkg/workflow/engine_config_dir.go, where they now resolve the engine config directory via the AgentFileProvider interface (GetAgentManifestPathPrefixes()) from the global EngineRegistry — replacing a hardcoded switch statement with a single source of truth.

• Behavior preserved

  • Public extraction APIs are unchanged (ExtractInlineSkills, ExtractInlineSubAgents).
  • Existing error text/log semantics for duplicate names remain intact.
  • Engine-specific path mapping is now driven by the engine registry, so new engines are covered automatically without code changes.

• Bonus fix

  • Engines not previously handled by the switch (pi, crush, opencode, antigravity) now correctly resolve to their own config directories (e.g. .pi/agents) instead of falling back to .github/.

• Result

  • Removes parallel implementations of the same parsing flow, centralizes the section-boundary algorithm, and eliminates the hardcoded engine→directory mapping in favour of the agentic engine interface.

// pkg/workflow/engine_config_dir.go
func GetEngineSkillDir(engineID string) string {
    return engineConfigBaseDir(engineID) + "/skills"
}

func GetEngineSubAgentDir(engineID string) string {
    return engineConfigBaseDir(engineID) + "/agents"
}

func engineConfigBaseDir(engineID string) string {
    registry := GetGlobalEngineRegistry()
    engine, err := registry.GetEngine(strings.ToLower(engineID))
    if err == nil {
        if provider, ok := engine.(AgentFileProvider); ok {
            if prefixes := provider.GetAgentManifestPathPrefixes(); len(prefixes) > 0 {
                return strings.TrimSuffix(prefixes[0], "/")
            }
        }
    }
    return ".github"
}

[Copilot]

Pull request overview

Consolidates duplicated inline-section parsing logic between the inline skill and sub-agent extractors into a shared helper file, reducing drift risk while preserving public API behavior.

Changes:

• New pkg/parser/inline_section_helpers.go with shared helpers (collectH2Positions, extractInlineSection, nextH2After, validateUniqueInlineSectionNames, engineConfigDir).
• inline_skill_extractor.go and sub_agent_extractor.go refactored to delegate to the shared helpers; duplicated regexes and switch statements removed.

Show a summary per file

File	Description
pkg/parser/inline_section_helpers.go	New shared helpers for H2 boundary discovery, section slicing, duplicate name validation, and engine config dir resolution.
pkg/parser/inline_skill_extractor.go	Removes duplicated skill-specific helpers and regex; delegates to shared helpers.
pkg/parser/sub_agent_extractor.go	Removes duplicated sub-agent helpers and regex; delegates to shared helpers.

Copilot's findings

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• Files reviewed: 3/3 changed files
• Comments generated: 0

[pelikhan]

@copilot lint go https://github.com/github/gh-aw/actions/runs/26765630225/job/78891087186

[Copilot]

@copilot lint go https://github.com/github/gh-aw/actions/runs/26765630225/job/78891087186

Fixed in commit fix: go fmt formatting in inline_skill_extractor and sub_agent_extractor. The indentation inside the closure bodies in validateUniqueInlineSkillNames and validateUniqueSubAgentNames was off by one tab level — go fmt corrected both.

[pelikhan]

@copilot use agentic engine interface to resolve this folder

[Copilot]

Done. engineConfigDir is removed from parser/inline_section_helpers.go. GetEngineSkillDir and GetEngineSubAgentDir are now in pkg/workflow/engine_config_dir.go and use AgentFileProvider.GetAgentManifestPathPrefixes() from the global EngineRegistry to resolve the directory — no more hardcoded switch. As a side-effect, the pi engine (and any future engines) now automatically get the correct directory without requiring a code change. The pi golden file was updated accordingly (.pi/agents/.pi/skills instead of the old .github/ default).