The tier axis comes out of the git stack — compose unconditional, postures mode-driven

HistoryStore.compose(boardRoot📒) returns non-optional and runs for
every session — the nil the gate produced was the only nil it ever had.
makeHistoryProvider is a one-axis decision: git-mode boards bind the git
provider, everything else native, in every tier; Session.tier stays
recorded, dormant. BoardGitSection shrinks to the four mode postures
(.absent and .proPointer die, BoardGitNote and the .git probe with them);
every board carries all three popover tabs (BoardInfoTab.available
retired); the titlebar branch shows on any git-mode board; the settings
sheet and card History section stop reading tier. InertGitTests is
repurposed as UntouchedGitTests — the file layer still never opens .git,
now load-bearing for mode-none boards. The accessibility audit reaches the
settings sheet at last: the fixture board hosts it in every tier, so the
free-fixture disabled-row test becomes an open-and-audit test.

Claude-Session: https://claude.ai/code/session_01SR4XGjmBE16ZUYWpfFHXwY

Kanban/UI/Card/CardHistorySection.swift

@@ -83,9 +83,15 @@ enum CardHistoryRows {
 /// ### Its existence is the section's visibility rule
 ///
 /// "The section is **absent** on boards without app-managed git (mode none, repo-nested) — same
-/// honesty rule as the popover's git section" (05 ▸ History), and the free tier has no git state at
-/// all (12-editions.md). So the host builds one of these only in mode `git`, and `nil` is the whole
-/// of the absence — no placeholder, no empty header, nothing to explain.
+/// honesty rule as the popover's git section" (05 ▸ History). So the host builds one of these only
+/// where the board's history is genuinely git-backed — its `HistoryStore` in mode `git` — and `nil`
+/// is the whole of the absence: no placeholder, no empty header, nothing to explain.
+///
+/// **Per board, never per tier** (12-editions.md ▸ PIVOT 2026-08-07). 12's old tier matrix listed
+/// the card History sidebar as a Pro row, so the section's absence used to have two causes at once —
+/// a gitless board, or a free-tier session with no git state to ask. Git is tier-independent now:
+/// the one question left is whether *this board* has a repository the app manages, which is the
+/// question 05 was always asking.
 ///
 /// ### It re-reads rather than subscribes
 ///