variance-analysis

## Instructions Use this skill whenever the controller asks for a variance review, a chart, or any "is this number reasonable?" sanity check. This is the **computation surface** — it uses `code_interpreter` against the numbers returned by **sap-s4**. Do NOT do mental math on financial figures; always send the numbers through this skill. ### Workflow 1. Pull the raw rows via `sap_get_variance_analysis` for the requested period. 2. Pass the resulting JSON into `code_interpreter` with the analysis script below — DO NOT retype the numbers. 3. The script emits: - A compact table per flag bucket (`investigate`, `watch`, `normal`) - A matplotlib bar chart saved to `/tmp/variance-<period>.png` - A CSV of the underlying data at `/tmp/variance-<period>.csv` for the close pack 4. Reference both file paths in your response so the **file-sharing** convention picks them up. ### Reference script (variance_analysis.py) The full script is in `scripts/variance_analysis.py` in this skill's directory. Read it once with the file_read tool, then invoke it via `code_interpreter` — DO NOT inline the script body in your response. The script signature: ```bash python /app/use-cases/finance-close/skills/variance-analysis/scripts/variance_analysis.py \ --period 2026-05 \ --rows-json '<the JSON returned by sap_get_variance_analysis>' \ --out-dir /tmp ``` Outputs to stdout: the per-bucket tables. Outputs to disk: `/tmp/variance-2026-05.png` and `/tmp/variance-2026-05.csv`. ### Driver decomposition heuristic The script also classifies each `investigate` row with one of: - **price** — `gl_account.type == "OpEx"` and prior-year run-rate close, but unit-rate moved (Sentinel-style licence uplift) - **volume** — variance scales with a known cost-centre headcount / production-order change - **one-off** — single JE >50% of the variance (manual / accrual / reclass), look up via `sap_list_journal_entries` - **mix** — none of the above; flag for owner explanation This is a **suggestion** to seed owner commentary, not a determination. Always present it as `Suggested driver: …` and let the human override. ### When NOT to use - For a single number / single GL → just cite `sap_get_variance_analysis` inline; don't build the whole chart. - For non-finance computation (e.g. parse an email body) → use `code_interpreter` directly without this skill.