When the model fires \`todo_update\` / \`checklist_update\` repeatedly
during a long run, the live transcript previously dumped the full
checklist card (header + every item + progress) on every call. In
sessions with 20+ items and a dozen status flips the same item list
appears over and over, drowning the actual work.
Now: when a checklist update output starts with the
"Updated todo #N to STATUS" prefix the tool already emits, the live
renderer shows a compact one-line state-change card —
\`Todo #N: <title> → STATUS\` — plus a \`M/N · pct%\` summary in the
header and a \`N items (Alt+V for full list)\` affordance underneath.
The full item list is still reachable via the existing detail pager.
Falls back to the full-card render path for:
- \`todo_write\` / \`checklist_write\` (no "Updated" prefix — first
emission of the list)
- transcript-mode replays (the user wants the full snapshot when
scrolling history)
- malformed prefixes (parse failure → fall through, never crash)
### What's wired
- New \`parse_update_prefix(output)\` parser handles both
\`Updated todo #N to STATUS\` and \`Updated checklist #N to STATUS\`
forms.
- New \`render_checklist_change_card\` builds the compact card. Looks
up the title from the snapshot's items array (id is 1-indexed),
falls back to \`(missing title)\` if the id is out of range.
- \`try_render_as_checklist\` calls the change-card path only in
\`RenderMode::Live\` and only when the parser matches. Pre-existing
cases (writes, transcript replay) keep the full-card behavior.
### Tests
- 4 parser tests: todo form, checklist form, write outputs falling
through, malformed prefixes falling through.
- 2 renderer tests: compact card shows only the changed item (with
assertions that other titles do NOT appear), missing-title path.
### Verification
cargo fmt --all -- --check ✓
cargo clippy --workspace --all-targets --all-features --locked -- -D warnings ✓
cargo test --workspace --all-features --locked ✓ 1834 + supporting
Closes#403
Co-Authored-By: Claude Opus 4.7 (1M context) <noreply@anthropic.com>
Hunter Bown
c52f2c46f1