altimate-code: Skill for OpenCode

dbt Impact Analysis

Requirements

Agent: any (read-only analysis) Tools used: bash (runs altimate-dbt commands), read, glob, dbt_manifest, lineage_check, dbt_lineage, sql_analyze, altimate_core_extract_metadata

When to Use This Skill

Use when the user wants to:

• Understand what breaks if they change a model
• Evaluate downstream impact before shipping
• Find all consumers of a model or column
• Assess risk of a refactoring

Do NOT use for:

• Creating or fixing models → use dbt-develop or dbt-troubleshoot
• Adding tests → use dbt-test

Workflow

1. Identify the Changed Model

Accept from the user, or auto-detect:

# From git diff
git diff --name-only | grep '\.sql$'

# Or user provides a model name
altimate-dbt compile --model <name>    # verify it exists

2. Map the Dependency Graph

altimate-dbt children --model <name>    # direct downstream
altimate-dbt parents --model <name>     # what feeds it

For the full downstream tree, recursively call children on each downstream model.

3. Run Column-Level Lineage

With manifest (preferred): Use dbt_lineage to compute column-level lineage for a dbt model. This reads the manifest.json, extracts compiled SQL and upstream schemas, and traces column flow via the Rust engine. More accurate than raw SQL lineage because it resolves ref() and source() to actual schemas.

dbt_lineage(model: <model_name>)

Without manifest (fallback): Use lineage_check on the raw SQL to understand:

• Which source columns flow to which output columns
• Which columns were added, removed, or renamed

Extract structural metadata: Use altimate_core_extract_metadata on the SQL to get tables referenced, columns used, CTEs, subqueries — useful for mapping the full dependency surface.

4. Cross-Reference with Downstream

For each downstream model:

1. Read its SQL
2. Check if it references any changed/removed columns
3. Classify impact:

Classification	Meaning	Action
BREAKING	Removed/renamed column used downstream	Must fix before shipping
SAFE	Added column, no downstream reference	Ship freely
UNKNOWN	Can't determine (dynamic SQL, macros)	Manual review needed