Phase 3 — Move canonical heads and migrate projections

State: waits for consumer convergence and the I1/I2 mechanisms.

Outcome

Add kb/tags/ as the canonical head collection only after consumers can find heads in their current locations through the resolver. Relocate the corpus and installed projection as a breaking representation migration, not as part of the semantic foundation patch.

Work

  1. Add the kb/tags/ collection contract and landing. Define its introduction quality goal, common meaning/use/boundary/route/stopping prefix, and cross-library link grammar.
  2. Re-derive all transitional heads and participating tags. Move every head to a direct child of kb/tags/; Phase 2 has already required and dispositioned a head for each participating tag, including trace-learning. Never freeze a head count in migration code or acceptance.
  3. Let filenames supply canonical tag identity. Remove index_source: tag, index_key, the legacy tags-README.md hub, and index_source: tag-indexes after moving useful hub prose to the landing.
  4. Update footer routing, generated augmentation, review-sweep scope, redirects, and every path-constructing consumer. Switch resolve_tag_head from legacy metadata lookup to direct canonical construction without retaining a legacy fallback.
  5. Give every projection-sensitive head link an explicit I2 disposition. Scaffold an empty host tag collection at kb/tags/ and project eligible Commonplace heads to commonplace-library/kb/tags/. Resolve each within its owning kb-root; do not merge membership or marks across roots.
  6. Supply the move map, obsolete paths, and sentinel user content to I1's ownership-aware upgrade mechanism. Do not create a tag-specific updater.
  7. Retire both adopted proposals and annotate prior tag ADRs forward after all source and installed fixtures pass.

Acceptance

  • Every tag on an eligible artifact reaches its own root's canonical head.
  • Host and projected Commonplace heads, marks, and generated listings remain independent; an explicitly selected reader root is independent as well.
  • No live duplicate head identity or legacy hub identity remains.
  • Every shipped head link resolves in the selected installed edition.
  • Fresh and upgraded fixtures converge on commonplace-managed paths while preserving user additions.
  • Resolver, validation, ProperDocs, connect, relocation, upgrade, site-build, and full-suite checks pass in their appropriate packets.