docs: record session (#36)

Journal entries for the #33/#34 split and the #36 coverage counter
(two bugs caught before merge in the latter), plus the vignette
obligation filed as #72. Status board regenerated and republished.

Co-Authored-By: Claude Sonnet 5 <noreply@anthropic.com>

pm/JOURNAL.md

@@ -12,3 +12,22 @@ file carries the reasoning and the pointers.
 - **Refs** — commits, issues, decision records.
 
 ---
+
+## 2026-09-09 · model · #36 coverage counter finished, two bugs caught before merge
+
+**Why:** the drafted n_units_collected fix (uncommitted) derived its candidate
+cohort from category-filtered results instead of the caller's full expected
+cohort, and hardcoded a view name absent below schema_version 5 -- both
+silent on the fixture, both would have shipped without an independent review
+pass before merge.
+**Obligates:** #72
+**Refs:** #36, b41d5ee, PR#71
+
+## 2026-09-09 · model · #33/#34 split into independently-tested commits
+
+**Why:** #33's own branch had its tests sitting uncommitted, and quietly bundled
+a behavior change (#34) into what its commit message called a pure refactor;
+splitting them let each pass CI with its own tests instead of merging on a
+false "tests pass" claim.
+**Obligates:** (none)
+**Refs:** #33, #34, 0c7c7eb, 392643b, d0d724c, 9f5cd98, PR#69, PR#70