Module render 

Banner text formatter.

Produces a multi-line, ≤6-line / ≤400-char string the adapters append to whatever additional_context they already produce. The shape mirrors the spec in the original feature request:

DiffLore: 2 new rules learned for this repo since 2026-05-20T14:30:00Z
  · Return 413 for body size limit errors  ← from review by alice (PR #88)
  · Wrap context cancellation in errgroup   ← from PR merge signature
Run `difflore status` to see the value loop.

Each bullet is at most ~80 chars (60-char title cap + provenance suffix). The closing call-to-action is fixed so the agent can learn to discover the status surface from any session.

Functions

format_banner

Build the banner from rule rows + the previous-session label. prev_label is either an RFC-3339 timestamp (“2026-05-20T14:30:00Z”) or the synthetic phrase “the start of this repo” used on first session — formatter doesn’t care which, it just inlines whatever the caller computed.