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/History/CardWindowUndo.swift

@@ -13,11 +13,12 @@ import Foundation
 ///
 /// ### Two jobs, and the second is why this is a type rather than a stored provider
 ///
-/// **The fine stack**: an ordinary `NativeHistoryProvider`, in *both* tiers. The steps a card window
+/// **The fine stack**: an ordinary `NativeHistoryProvider`, on *every* board. The steps a card window
 /// registers are values-based inverses at the Writer boundary — the same shape whatever substrate the
-/// board's own history has — so a Pro git board's card window still walks its own gestures with the
-/// native grammar, and only the *coarse* close unit is tier-split ("one native board step, or one
-/// commit" — 06-history-undo.md ▸ Undo routing).
+/// board's own history has — so a git board's card window still walks its own gestures with the
+/// native grammar, and only the *coarse* close unit splits by substrate ("one native board step, or
+/// one commit" — 06-history-undo.md ▸ Undo routing). The split was written as a tier split and is a
+/// board split since 12-editions.md ▸ PIVOT 2026-08-07; nothing in this type ever read either.
 ///
 /// **The fold**: window close registers "one coarse step ... whose undo restores the card subtree to
 /// its session-start state ... and whose redo reapplies the net effect". That net effect is exactly