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/Board/BoardToolbar.swift

@@ -44,7 +44,8 @@ extension NSToolbarItem.Identifier {
 /// enable exactly when that board has a step to cross and no read-only lock stands
 /// (13-native-undo.md ▸ Rules). **Every board has undo in every tier**, so there is no tier-shaped
 /// disablement to write: 03's parenthetical about boards without undo is 06's *git* substrate, which
-/// only a Pro subscription binds.
+/// a board binds by being in git mode — on any tier since 12-editions.md ▸ PIVOT 2026-08-07, and
+/// under a Pro subscription before it.
 ///
 /// Their labels are the design's one exception to the menu-title rule: `NSUndoManager` rewrites the
 /// *menu* titles as the stack changes ("Undo Move Card"), which a toolbar label does not track, so