Demo s038: Filter compares value to NULL with equals

[anandgupta42]

Demo scenario

• Scenario ID: s038
• Branch: demo/s038-equals-null-filter
• Risk category: sql_correctness
• Expected reviewer verdict: COMMENT
• Expected deterministic evidence: altimate_core.check:not_null_comparison

Customer walkthrough

Shows SQL that looks valid but never matches NULLs.

When presenting this PR, first show that dbt can build the project, then show the reviewer finding. The point is that the reviewer catches or ignores the change from deterministic dbt/SQL evidence, not from advisory AI text.

Validation command

rm -f demo.duckdb demo.duckdb.wal
dbt build --profiles-dir . --target dev
dbt compile --profiles-dir . --target dev
dbt docs generate --profiles-dir . --target dev
bun --conditions=browser /Users/anandgupta/codebase/altimate-code/packages/opencode/src/index.ts review \
  --cwd=/Users/anandgupta/codebase/altimate-code/demo/dbt-pr-review-demo \
  --base=main \
  --head=HEAD \
  --mode=gate \
  --manifest=/Users/anandgupta/codebase/altimate-code/demo/dbt-pr-review-demo/target/manifest.json \
  --json \
  --no-ai

Acceptance notes

• DuckDB default warehouse.
• AI disabled with --no-ai.
• Included in the final local corpus matrix: 50/50 branches matched expected verdicts.
• Real-world corpus floor held at 15/15 caught bad cases and 0/5 false positives.

[github-actions]

💬 Reviewed with comments — 3 warning, 1 suggestion (lite tier)

⚙️ Lint-only run — no dbt manifest/warehouse was available, so lineage, equivalence and
data-impact checks were skipped. Wire manifest_path (and optionally warehouse creds) for the full verdict.

⚠️ Warning (3)

• fct_customer_orders: not_null_comparison
  Comparison with NULL using = or != always yields NULL
  _{models/marts/fct_customer_orders.sql:28 · sql_correctness}
• fct_customer_orders: refactor could not be proven equivalent
  The logic of fct_customer_orders changed and equivalence could not be decided (no schema, or unsupported SQL). Treat as a potential behavior change and verify with a data-diff.
  _{models/marts/fct_customer_orders.sql · unverified · semantic_change}
• fct_customer_orders: exposes Name column customer_name
  This change surfaces a Name-classified column customer_name (confidence 75%). Confirm masking / access policy before merging to a non-restricted schema; suggested masking: '***MASKED***'.
  _{models/marts/fct_customer_orders.sql · pii_exposure}

💡 Suggestion (1)

• fct_customer_orders: missing_table_alias
  Multi-table query without aliases for: orders, customers
  _{models/marts/fct_customer_orders.sql:8 · sql_quality}

---

_{altimate dbt-pr-review · verdict COMMENT · signed sha256:00d86cfb459… · manifest 35612d7229}

[github-actions]

💬 Reviewed with comments — 3 warning, 1 suggestion (lite tier)