Two unrelated failing tests, investigated in order.

test_agreement_distribution_within_bounds asserted tracks_total == 73, a snapshot
from before yesterday's catalog rebuild (73 -> 81 tracks). Bumping it to 81 would
just re-freeze the same brittleness. Replaced it with
test_tracks_total_matches_the_generated_catalog: assert the live view's
tracks_total equals the CHECKED-IN catalog.generated.json's n_tracks. That file is
a 1:1 derivation of this same view, so the two can only disagree on a real
regression (corpus changed but catalog not regenerated, or the pipeline
dropped/duplicated a row) — never on honest growth. Verified it still fails by
corrupting n_tracks and re-running.

test_real_backlog_coverage_does_not_regress: opal-festival-2024's recovered
tracks fell from 13/14 to 3. The obvious suspect was e8f7066a (yesterday's
tools/setlist.py soundcheck filter) — ruled out by inspection (e8f7066a touches
only tools/setlist.py + its test, nothing under armada/tide-table) and by
bisection: replaying backlog_setlists.py's ANCHORS against every historical
backlog.md since the anchors were authored (5acf72f7, 2026-06-06) shows
n_resolved holding at 14 across ten intervening commits and only breaking at
49e1b78e ("update: post cosmic", 2026-08-23).

The real bug: ANCHORS keyed gigs by a raw 1-based LINE NUMBER pinned once against
a single backlog.md snapshot. backlog.md is PLN's running journal, not a stable
document, so every one of those ten commits that inserted lines earlier in the
file silently shifted every anchor below it. Opal 2024's anchor drifted through
blank lines and a lucky near-miss for months (the collected span still happened
to contain the same real content), then 49e1b78e pushed the drift past the
header entirely into the tail of the PREVIOUS gig's block, collecting 3
unrelated lines instead of the setlist.

Fix: anchor by the header's exact TEXT, resolved fresh against the live file on
every build() (resolve_anchors()), instead of a line number frozen at authoring
time. Self-healing against drift elsewhere in the file; raises loudly if a
heading is ever actually renamed or duplicated, rather than silently
mis-anchoring. The three anchors that carried an explicit end-of-block bound
(opal-2025/Latin-Heritage bleed, mephisteuf's commented block, the 38c3-toilet
cross-check) now store that bound as a line-count SPAN measured from the anchor,
since that span lives inside the block and doesn't move when the anchor does.

tools/setlist.py's soundcheck filter (e8f7066a) is untouched and still yields 15
entries for OPAL 2026 — never the culprit here, just an unrelated same-day
change that made a plausible but wrong prime suspect.

Full suite: 468 passed, 2 skipped (465 baseline + 2 fixed + 1 new regression
test), up from 2 failing.