# Phase 22 — SQL diagnostics and plan observations

- Adds read-only interpretation of tabular MySQL EXPLAIN output: full scans, index scans, missing selected index, temporary tables, filesort and estimated row counts.
- Adds Copy Plan for tabular and JSON EXPLAIN output.
- Displays MySQL execution errors directly above the SQL editor, with selectable error text. No inaccurate error-line highlighting is attempted.
- Index observations are explicitly advisory and do not generate or execute DDL.
- Preserves Phase 21 and earlier project files.

Build and runtime validation on macOS / a MySQL server are still required.