Add knownSections to Plan Rune Content Models

Summary

Plan Runes defines named sections with aliases for work, bug, and decision runes. The current implementation uses a generic sections content model — any H2 heading creates a section, but headings aren't validated or aliased.

The knownSections feature would let content models declare expected section names and aliases, enabling:

• Validation: warn if a required section is missing (e.g., work item without "Acceptance Criteria")
• Aliases: "AC", "Criteria", "Done When" all map to "Acceptance Criteria"
• Templates: editor can suggest section names when authoring

Proposed Known Sections

work:

• Acceptance Criteria (aliases: Criteria, AC, Done When)
• Edge Cases (aliases: Exceptions, Corner Cases)
• Approach (aliases: Technical Notes, Implementation Notes, How)
• References (aliases: Refs, Related, Context)
• Verification (aliases: Test Cases, Tests)

bug:

• Steps to Reproduce (aliases: Reproduction, Steps, Repro)
• Expected (aliases: Expected Behaviour)
• Actual (aliases: Actual Behaviour)
• Environment (aliases: Env)

decision:

• Context
• Options Considered (aliases: Options, Alternatives)
• Decision
• Rationale (aliases: Reasoning, Why)
• Consequences (aliases: Impact, Trade-offs)

Acceptance Criteria

• knownSections supported in the content model framework (packages/runes/src/content-model/)
• Work rune declares known sections with aliases
• Bug rune declares known sections with aliases
• Decision rune declares known sections with aliases
• Alias matching is case-insensitive
• Unknown sections still pass through via sectionModel fallback
• Validation warns on missing required sections (if any declared as required)
• Tests for alias resolution and fallback behaviour

Dependencies

• Plan Package Hardening — accepted spec that defines the full knownSections design for plan runes

References

• Declarative Content Model — Specification (Declarative Content Model — framework-level knownSections design)
• Plan Runes (Plan Runes — section definitions for work/bug/decision)
• Plan Package Hardening (Plan Package Hardening — unblocks this work item)

Resolution

Completed: 2026-04-12

Branch: claude/spec-037-breakdown-docs-Whj40

What was done

• Added KnownSectionDefinition type to packages/types/src/content-model.ts
• Added knownSections field to SectionsModel interface
• Implemented matchKnownSection() in packages/runes/src/lib/resolver.ts
• Resolver adds $canonicalName to resolved sections when matched
• Declared knownSections for work (6 sections), bug (4 sections), decision (5 sections)