variance-analysis

name	variance-analysis
description	Compute month-end variance — driver decomposition (volume/price/mix/one-off heuristic), anomaly flags, and a matplotlib bar chart of variance % by cost centre saved to /tmp for download.
enabled	true

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:

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.