lineage-diff

# Lineage Diff ## Requirements **Agent:** any (read-only analysis) **Tools used:** lineage_check, read, bash (for git operations), glob Compare column-level lineage between two versions of a SQL model to identify changes in data flow. ## Workflow 1. **Get the original SQL** — Either: - Read the file from disk (current committed version) - Use `git show HEAD:path/to/file.sql` via `bash` to get the last committed version - Accept the "before" SQL directly from the user 2. **Get the modified SQL** — Either: - Read the current (modified) file from disk - Accept the "after" SQL directly from the user 3. **Run lineage on both versions**: - Call `lineage_check` with the original SQL - Call `lineage_check` with the modified SQL 4. **Compute the diff**: - **Added edges**: Edges in the new lineage that don't exist in the old - **Removed edges**: Edges in the old lineage that don't exist in the new - **Unchanged edges**: Edges present in both 5. **Report the diff** in a clear format: ``` Lineage Diff: model_name ═══════════════════════════ + ADDED (new data flow): + source_table.new_column → target_table.output_column - REMOVED (broken data flow): - source_table.old_column → target_table.output_column UNCHANGED: 5 edges Impact: 1 new edge, 1 removed edge ``` ## Usage The user invokes this skill with a file path: - `/lineage-diff models/marts/dim_customers.sql` — Compare current file against last git commit - `/lineage-diff` — Compare staged changes in the current file ## Edge Matching Two edges are considered the same if all four fields match: - `source_table` + `source_column` + `target_table` + `target_column` The `transform` field is informational and not used for matching. Use the tools: `lineage_check`, `read`, `bash` (for git operations), `glob`.