Build HistoryStore — opt-in git and mode detection

The pro-m1 foundation card. SwiftGitX 0.4.0 (bundled libgit2, the
pathfinder's pin) joins the one target; new Kanban/Git/ holds
BoardGitMode (pure nearest-.git-wins detection, .git-as-file counts,
NSString ancestor walk), HistoryStore (@MainActor @Observable;
compose() is the tier gate — free tier gets no object, no detection,
no stat), GitRepository (scope-confined SwiftGitX handles: create =
init + HEAD forced to main + whole-tree "Initial board state" commit;
branch reads incl. unborn/detached; path-history ranks), GitIdentity
(derived default as a pure function + repo-local config reader — not
libgit2's merged ladder), and GitPathHistory (Mutex-guarded lazy
ranker). beginSession composes the git state beside the tier and
feeds BoardStore.makeIdentityHistoryRanker; git-mode loads pass the
git-backed IdentityHistoryRanker to BoardLoader. The popover's git
slot resolves a pure five-way matrix: free tier unchanged (absent /
BoardGitNote), Pro mode-aware — Add Git on mode none, honest prose on
repo-nested, read-only branch line on git. Provider binding
unchanged: both tiers still bind native until the undo/redo card.

42 new tests across 8 suites, all repositories built through bundled
libgit2; InertGitTests untouched and green. 2194 tests / 375 suites.

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

README.md

@@ -47,7 +47,7 @@ Lanework is in early development. This list tracks what has actually shipped and
 
 - **Raw source** — View ▸ Raw Source (⌥⌘E) swaps the card window's whole content area — title, body and sidebar — for the literal `index.md` in a monospaced editor with Cancel and Apply. It's the escape hatch that keeps everything reachable in-app: unknown keys an agent added, hand-written comments, exotic YAML the app has no control for. Entering flushes whatever you were typing and then reads the file fresh off disk, never an in-memory copy. Apply validates through the very same fail-fast parse the loader uses — a broken proposal stops with a detailed alert naming the line, source mode stays open with your text, and the file on disk is untouched — and a valid one is written byte for byte, the only write in the app that neither stamps `modified` nor clears a `modified-by` you typed or kept, because you wrote those bytes and nothing may quietly edit them. The reload then refreshes every window. Escape is Cancel, ⌘↩ is Apply, ⌥⌘E toggled off applies too, Return just types; Cancel and closing the window discard without ceremony, and a card deleted out from under an open buffer discards it rather than letting a stale Apply undelete the card. ⌘E stands down while source mode is up, ⌘F still finds, and ⌘Z is the editor's own undo. A file that isn't valid UTF-8 declines to open as source rather than showing you a lossy guess of it.
 
-- **The board popover** — a quiet chevron beside the window title (File ▸ Board Info, ⌘I, which toggles it) opens the board's one configuration surface. Renaming edits the board's frontmatter `title` and nothing else — the folder is never renamed, so the app's display name and the Finder document name are free to diverge — and clearing the field removes the key entirely, dropping the window title back to the folder name rather than to "Untitled"; the edit commits on Return and on click-away, Escape abandons it, and an unchanged title writes nothing at all. Below it sits the same style editor every other anchor uses, aimed permanently at the board; on an ordinary board the popover ends there, and only a board carrying a `.git` gets a closing note — "This board has a git history. Lanework Pro works with it." The read-only lock disables the surface without closing it.
+- **The board popover** — a quiet chevron beside the window title (File ▸ Board Info, ⌘I, which toggles it) opens the board's one configuration surface. Renaming edits the board's frontmatter `title` and nothing else — the folder is never renamed, so the app's display name and the Finder document name are free to diverge — and clearing the field removes the key entirely, dropping the window title back to the folder name rather than to "Untitled"; the edit commits on Return and on click-away, Escape abandons it, and an unchanged title writes nothing at all. Below it sits the same style editor every other anchor uses, aimed permanently at the board; on an ordinary free-tier board the popover ends there, and only a board carrying a `.git` gets a closing note — "This board has a git history. Lanework Pro works with it." Under a Lanework Pro subscription that slot becomes the board's git section instead, and it follows the board's mode: a board with no repository offers **Add Git**, a board that lives inside somebody else's repository gets a short honest explanation rather than a hidden or greyed-out action, and a git board shows its current branch, read-only. The read-only lock disables the surface without closing it.
 
 - **Customizable toolbars** — both windows carry a real macOS toolbar: right-click ▸ Customize Toolbar…, drag to rearrange, the system overflow, and the Icon and Text / Icon Only / Text Only display options, with your arrangement remembered across launches. They are pure enhancement — every item is a menu command with a shortcut, so removing all of them costs you nothing but a click. The board ships with the search field alone, trailing, and offers New Card, New Lane, Undo, Redo and Show Trash in the palette (Undo and Redo validate exactly as the Edit menu's rows do, and keep static labels because the menu's titles rewrite themselves); the board popover deliberately has no item, since the window-title chevron is its home. Take the search field out and ⌘F still summons search — the field appears in a strip just under the title bar and stays until the search clears, keeping the keyboard while you type. The card window ships Edit Body · Raw Source · Add Attachment, the first two as toggles showing their on-state, with Edit Body disabling while raw source is up and Add Attachment live in every mode.
 
@@ -59,7 +59,9 @@ Lanework is in early development. This list tracks what has actually shipped and
 
 - **App identity — icon, versioning, About** — the app carries its three-lane glyph icon and a real About window: icon, copyright, version and build stamped at build time from git (`CFBundleVersion` = commit count, plus `BuildDate` and `BuildHash` in the Info.plist — never a hardcoded string), the version line opening the bundled end-user changelog, and the ISC license one link away. The box carries the one quiet line naming Lanework Pro — one of the three places the app names it at all, per the quiet-signposts rule (DESIGN/12).
 
-- **Tiers and the Lanework Pro subscription** — one app, one download, one on-disk format. The free tier is the complete board experience and everything above is in it; **Lanework Pro is an auto-renewable subscription inside the app**, bought and managed in a Pro section of Settings (⌘,) — price, Subscribe, Manage Subscription, Restore Purchases, and one quiet line when the App Store can't be reached. What the subscription will unlock is git: opt-in init and adoption, git-backed undo and history surfaces, branches, remotes and push/pull (DESIGN/06, DESIGN/07). **None of that is built yet** — pro-m1 and pro-m2 are the milestones that build it, and until they ship both tiers run the same native undo stack over the same inert-`.git` posture. What exists today is the infrastructure it lands on: the entitlement, the seam, and the storefront. The entitlement is a **local read, never a network call** — StoreKit's own signed on-device transaction store, reduced to two cached facts and resolved by a pure function at board-session composition, so opening a board never waits on the App Store and offline with an active subscription is indistinguishable from online. Offline grace resolves toward the paying user: an expiry passing while the device hasn't heard from the App Store, with the last known state renewing, holds the subscription until StoreKit actually answers, while a cancellation lapses at its expiry either way. A fresh install that has never been online reads free and corrects itself on the first refresh; unsubscribed and lapsed are *one* state, with nothing anywhere distinguishing them. The tier binds **per board session at composition** and is recorded on the session, so a lapse never interrupts an open board — and because subscribing takes effect at each board's next open, the purchase flow offers once to close and reopen the boards you have open. Only the Settings section touches the network: product loading, purchasing and Restore Purchases live there and nowhere else.
+- **Tiers and the Lanework Pro subscription** — one app, one download, one on-disk format. The free tier is the complete board experience and everything above is in it; **Lanework Pro is an auto-renewable subscription inside the app**, bought and managed in a Pro section of Settings (⌘,) — price, Subscribe, Manage Subscription, Restore Purchases, and one quiet line when the App Store can't be reached. What the subscription unlocks is git: opt-in init and adoption, git-backed undo and history surfaces, branches, remotes and push/pull (DESIGN/06, DESIGN/07). **The first of that is built** — see "Git integration" below — and the rest is pro-m1 and pro-m2's remaining work; until it ships both tiers run the same native undo stack, the free one over the same inert-`.git` posture. What exists today is the infrastructure it lands on: the entitlement, the seam, and the storefront. The entitlement is a **local read, never a network call** — StoreKit's own signed on-device transaction store, reduced to two cached facts and resolved by a pure function at board-session composition, so opening a board never waits on the App Store and offline with an active subscription is indistinguishable from online. Offline grace resolves toward the paying user: an expiry passing while the device hasn't heard from the App Store, with the last known state renewing, holds the subscription until StoreKit actually answers, while a cancellation lapses at its expiry either way. A fresh install that has never been online reads free and corrects itself on the first refresh; unsubscribed and lapsed are *one* state, with nothing anywhere distinguishing them. The tier binds **per board session at composition** and is recorded on the session, so a lapse never interrupts an open board — and because subscribing takes effect at each board's next open, the purchase flow offers once to close and reopen the boards you have open. Only the Settings section touches the network: product loading, purchasing and Restore Purchases live there and nowhere else.
+
+- **Git integration (Lanework Pro)** — git is **opt-in per board and never silent**. Under a subscription, a board's mode is detected freshly at every open, nearest-`.git`-wins: a `.git` at the board root means git mode, a `.git` only further up means the board lives inside somebody else's repository, and neither means no git at all. Detection is an open-time fact by design — a `git init` run in a terminal under an open board takes effect the next time you open it, and nothing watches for a repository appearing. **Adoption is not initialization**: a board whose folder already holds a repository (you cloned it, or you ran `git init` yourself) simply opens in git mode, with no dialog and no adoption step — the repository's presence *is* the opt-in, which is how a second machine joins a shared board. **Add Git** in the board popover is the only thing in the app that ever creates one: it initializes a repository in the board's folder and immediately commits the whole tree as "Initial board state", so the board is protected from the moment git exists, and it flips the open board into git mode on the spot. Commits are authored from the repository's own `.git/config` when it names an identity, and otherwise from your macOS account name and machine (the popover's identity fields land with a later card). A board inside an existing repository is left strictly alone — no nested repository, no commits into your project — and the popover says so in plain words instead of showing a disabled button. The git client is **bundled** (libgit2, in-process via SwiftGitX): nothing here shells out, and none of it needs git installed. Git history also settles duplicate-id collisions on git boards — of two folders claiming one identity, the path that entered history first wins. Still ahead in pro-m1/m2: auto-commit with semantic messages, git-backed undo/redo, branch switching, `.gitignore` seeding, and remotes.
 
 ## Development