# Month-over-month diff

A reusable skill the "Explain the variance, not just the number" recipe pulls in. Add it once and every agent on the team can use it.

Compare this month's flagged variances against last month's pack to
surface what's recurring.

## Method
1. Load last month's pack from `reports/budget-actuals/`.
2. Match flagged lines by owner and line item across the two periods.
3. Mark any line flagged in both months as recurring.
4. Note any line that cleared, flagged last month but not this one,
   and any newly flagged line.
5. Independently recount the recurring-line total against the raw
   flagged lists before reporting it.

## Rules
- Never report a recurring count that hasn't been recomputed from the
  two source lists this run.
- A line counts as recurring only if it was flagged in the
  immediately prior pack, not any earlier one.
- Where last month's pack is missing or unreadable, hold the diff and
  say so — never report zero recurring by default.
- Diff comparison window, always prior month or a configurable
  lookback (set on first run, then stored in memory).

## Output
A diff summary: `{recurring, newly_flagged, cleared}`, appended to
this month's pack.