Editor Behavior Doc Structure Cleanup

Goal

Make docs/editor-behavior/ easier to use before more protocol work lands.

The target split stays:

• README.md = entry map
• markdown-standards.md = authority and methodology
• markdown-editing-spec.md = readable law
• editor-protocol-matrix.md = exhaustive scenario matrix
• markdown-parity-matrix.md = family coverage gate
• markdown-editing-reference-audit.md = external reference evidence
• docs/research/systems/editor-behavior-architecture.md = long-horizon architecture
• references/* = corpus inventories and usage

Cleanup Rules

• delete stale copies instead of keeping “just in case” archaeology
• remove outdated draft language once the newer doc state supersedes it
• keep canonical examples in the spec, not entire family backlogs
• keep execution history in docs/plans/, not under docs/editor-behavior/

Findings

• docs/editor-behavior/plans/ was dead weight once execution moved to docs/plans/.
• the readable spec still duplicated family backlog material that belongs in the protocol matrix
• multiple docs still talked like the work was pre-audit even though the matrix is now filled for in-scope families

Progress

• 2026-04-03: removed stale reference/corpus plan copies from docs/editor-behavior/plans/
• 2026-04-03: trimmed duplicated family backlog sections out of markdown-editing-spec.md
• 2026-04-03: repointed README.md to the surviving docs and docs/plans/
• 2026-04-03: updated stale wording in surviving docs so they describe the current structure instead of an earlier draft stage