Home app-side state in the shared App Group container

Every edition declares group.dev.rzen.indie.Kanban and homes its app-side state there from day one (12-editions.md ruling 2026-07-29): - AppGroup namespace: container resolution with per-edition fallback when unprovisioned, shared UserDefaults suite, edition identity, and a unit-test-host redirect (the test host IS the app — its launch sweep and recents refresh must not touch the real shared container). - BoardRecord: bookmark/isOpenNow replaced by per-edition grants and openNow keyed by bundle id; hand-written Codable keeps legacy keys decoding (adopted in memory as the running edition's slots, upgraded on first save); every other field stays common. - RecentBoard gains needsReopen: no grant of ours but somebody's — first click runs an open panel pre-anchored at the recorded path, prompt "Grant"; recordOpen mints this edition's slot onto the matched shared record (path fallback only after identity fails and only against records holding no grant of ours, so re-granting never forks the record). - Cross-edition freshness: stat-cheap mtime+size stamp re-reads the registry when the sibling edition wrote it, so one edition's save never erases the other's records wholesale. - restorables() filters on this edition's open-now flags; the board popover gains BoardEditionPresence ("Also open in Lanework Pro"), pid-liveness-checked so crash residue never lies. - Clipboard staging store moves to the group container; the sweep claims doomed trees by atomic rename into .sweeping/ then deletes, so the sibling's concurrent sweep is a non-event. - Template store re-homed to the group container per the 09-templates re-ruling; scalars (quick-style recents, window size) move to the shared suite. - verify-editions.sh: 30 checks (each edition carries exactly the family group). No pathfinder 1.x migrator: 1.x predates the registry; state starts fresh in the group container. Claude-Session: https://claude.ai/code/session_01SR4XGjmBE16ZUYWpfFHXwY
2026-07-29 20:18:15 -04:00
parent a99e1a52f0
commit 566deab506
28 changed files with 1733 additions and 181 deletions
@@ -79,8 +79,7 @@ struct OpenRecentMenu: View {
        Menu("Open Recent") {
            ForEach(rows) { row in
                Button(row.displayName) {
-                    guard let url = row.url else { return }
-                    appModel.openBoard(at: url)
+                    appModel.open(row)
                }
                .disabled(!row.canOpen)
            }
@@ -291,7 +290,7 @@ struct DuplicateBoardCommand: View {
 /// rule covers File ▸ Duplicate". So the shape here is `DuplicateBoardCommand`'s, step for step —
 /// flush, then a cancellable copy off the main actor under an in-progress row — and the differences
 /// are all in the engine (`TemplateEngine.saveAsTemplate(boardAt:titled:into:)`): the destination is
-/// Application Support rather than a sibling, `.git` and `.trash/` are dropped rather than forked, a
+/// the app-side template store rather than a sibling, `.git` and `.trash/` are dropped rather than forked, a
 /// collision auto-renames rather than failing, and a `template:` key lands on the copy.
 ///
 /// **No save panel, ever.** The store is the app's own container — "friction-free sandbox writes, no
@@ -313,7 +312,7 @@ struct DuplicateBoardCommand: View {
 ///
 /// Board window only, and disabled under the read-only lock — with the exception 09 spells out and
 /// 02-architecture.md ▸ Live-reload resilience scopes: **under the unwritable-location lock alone it
-/// stays live**, because it "reads the board and writes Application Support" (archiving the
+/// stays live**, because it "reads the board and writes the app-side store" (archiving the
 /// read-only DMG board being inspected is a legitimate errand), *unless* an open Edit or raw-source
 /// session holds unsaved content — content that lock's suspended saves cannot flush, and which the
 /// template would therefore silently miss. The other two locks disable it outright: a vanished root
@@ -28,8 +28,23 @@ public enum WindowID {
 ///
 /// The keys are declared here rather than spelled at each `@AppStorage`, for the same reason
 /// `WindowID` exists.
+///
+/// ### The domain is the group's, not `.standard`
+///
+/// 02 § Per-board app state sends these to "the group's shared `UserDefaults` suite where a scalar
+/// fits" (ruled 2026-07-29; 12-editions.md), for the registry's reason exactly: a paying upgrader
+/// launches Pro onto their own settings rather than onto defaults. `AppGroup.defaults` is that suite,
+/// and it degrades to a plain named domain when the group is not provisioned — unshared, but working.
+///
+/// **Every reader and writer of these keys must name that suite.** A `@AppStorage` left to its own
+/// devices reads `.standard`, which after this ruling is a *different* domain — so the two views that
+/// bind one of these keys pass `store:` explicitly (`SettingsView`).
 public enum AppPreferences {

+    /// The domain every key here lives in. A stored `let` would capture a suite at type-load time;
+    /// this is a lookup of an object `UserDefaults` itself caches.
+    public static var defaults: UserDefaults { AppGroup.defaults }
+
    /// "Restore open boards at launch" (Settings, ⌘, — 11-command-nexus.md). **Default on.**
    public static let restoreOpenBoardsAtLaunchKey = "restoreOpenBoardsAtLaunch"

@@ -37,7 +52,7 @@ public enum AppPreferences {
    /// any scene exists. `object(forKey:)` rather than `bool(forKey:)` because the latter cannot
    /// tell "off" from "never set", and this preference defaults to *on*.
    public static var restoreOpenBoardsAtLaunch: Bool {
-        UserDefaults.standard.object(forKey: restoreOpenBoardsAtLaunchKey) as? Bool ?? true
+        defaults.object(forKey: restoreOpenBoardsAtLaunchKey) as? Bool ?? true
    }

    /// The last-used card-window size (05-card-window.md; 02 files it as app-wide, not per-board —
@@ -46,14 +61,14 @@ public enum AppPreferences {
    public static let lastCardWindowSizeKey = "lastCardWindowSize"

    public static var lastCardWindowSize: CGSize? {
-        guard let text = UserDefaults.standard.string(forKey: lastCardWindowSizeKey) else { return nil }
+        guard let text = defaults.string(forKey: lastCardWindowSizeKey) else { return nil }
        let size = NSSizeFromString(text)
        guard size.width > 0, size.height > 0 else { return nil }
        return size
    }

    public static func setLastCardWindowSize(_ size: CGSize) {
-        UserDefaults.standard.set(NSStringFromSize(size), forKey: lastCardWindowSizeKey)
+        defaults.set(NSStringFromSize(size), forKey: lastCardWindowSizeKey)
    }

    /// The quick-style row's recently-used backgrounds — an array of palette names / hex strings,
@@ -163,7 +178,7 @@ public final class AppModel {
    /// the registries' reason — app-scoped, and a test holds its own rather than colliding with the
    /// app's — and reached by the context menus through the environment, since a `BoardStore` is
    /// board-scoped and this list deliberately is not.
-    public let styleRecents = StyleRecents()
+    public let styleRecents: StyleRecents

    /// The app's one drag session (DRAG-REORDER.md; 04-interactions.md ▸ Drag and drop).
    ///
@@ -187,7 +202,7 @@ public final class AppModel {
    ///
    /// Building it here is also the **launch sweep** (04: "a sweep at launch"): the store's `init`
    /// reads the pasteboard once and collects every staged tree it no longer names.
-    public let clipboard = ClipboardStore()
+    public let clipboard: ClipboardStore

    // MARK: The provider seam

@@ -411,11 +426,25 @@ public final class AppModel {

    private static let logger = Logger(subsystem: "dev.rzen.indie.Kanban", category: "app-model")

-    /// The app builds one of these with the real registry file; a test passes its own path for the
-    /// same reason `BoardRegistry` takes one at all — "injecting it is how a test stays out of the
-    /// real Application Support directory".
-    public init(registryStorageURL: URL = BoardRegistry.defaultStorageURL) {
+    /// The app builds one of these with the real state home; a test passes its own for the reason
+    /// `BoardRegistry` takes a storage URL at all — "injecting it is how a test stays out of the real
+    /// Application Support directory", which after the 2026-07-29 ruling means **out of the shared App
+    /// Group container** (`AppGroup`). A suite that swept the real staging root would be sweeping the
+    /// developer's own clipboard, and now the sibling edition's too.
+    ///
+    /// `clipboardStagingRoot` is a separate parameter rather than derived from `registryStorageURL`'s
+    /// folder because the two are injected for different reasons and by different callers: the UI-test
+    /// fixture launch redirects both into one scratch root (`UITestLaunch`), a unit test usually wants
+    /// only one of them, and deriving would silently move a test's staging directory the day it moved
+    /// its registry file.
+    public init(
+        registryStorageURL: URL = BoardRegistry.defaultStorageURL,
+        clipboardStagingRoot: URL = ClipboardStore.defaultStagingRoot,
+        preferences: UserDefaults = AppGroup.defaults
+    ) {
        boardRegistry = BoardRegistry(storageURL: registryStorageURL)
+        styleRecents = StyleRecents(defaults: preferences)
+        clipboard = ClipboardStore(stagingRoot: clipboardStagingRoot)
        // Read once here rather than lazily, so File ▸ Open Recent is populated from the app's first
        // menu pass — a launch that restores boards never shows welcome, and a submenu that filled
        // in only after the first close would look broken. It costs one bookmark-resolution sweep at
@@ -518,6 +547,56 @@ public final class AppModel {
        openBoard(at: url)
    }

+    /// Opens a recents row — the one door for welcome's double-click, its Open item, and File ▸ Open
+    /// Recent, because a row has **two** ways of leading to a board now.
+    ///
+    /// An ordinary available row opens its URL. A row awaiting this edition's grant
+    /// (`RecentBoard.needsReopen` — a board the other edition minted the only bookmark for) runs the
+    /// re-grant panel first: "the first click runs an open panel pre-anchored at the recorded path:
+    /// one click + Grant per board, once per edition" (12-editions.md ▸ Distribution).
+    ///
+    /// Nothing else about the open differs. The granted URL goes through `openBoard(at:)` exactly as a
+    /// File ▸ Open… pick would, and `BoardRegistry.recordOpen` matches the *existing* shared record and
+    /// mints this edition's slot onto it — the other edition's grant, the frames, the counts and the
+    /// cached title all stay where they are.
+    /// Internal rather than `public` only because `WelcomeRow` is — the row derivation is a UI-layer
+    /// value, and nothing outside this module opens boards by row.
+    func open(_ row: WelcomeRow) {
+        if let url = row.url {
+            openBoard(at: url)
+            return
+        }
+        guard let anchor = row.regrantAnchor,
+              let granted = presentRegrantPanel(anchoredAt: anchor, boardName: row.displayName) else { return }
+        openBoard(at: granted)
+    }
+
+    /// The re-grant panel: an ordinary open panel, pre-anchored at the board's recorded path.
+    ///
+    /// **A panel and not an alert**, because the panel *is* the mechanism: a sandboxed app gains access
+    /// to a folder by the user choosing it, so there is nothing an intermediate explanation could add
+    /// that the panel's own message does not say better while doing the job.
+    ///
+    /// `directoryURL` is the recorded path itself, per the ruling. For a board that is a `.kanban`
+    /// package the panel therefore opens *inside* it — `treatsFilePackagesAsDirectories` is on for
+    /// `presentOpenPanel`'s reason (boards are packages *and* plain folders) — and Open with nothing
+    /// selected chooses the folder on display, which is the board. A board that has since moved leaves
+    /// the panel at the nearest surviving ancestor, which is the Finder behaviour and the honest one:
+    /// the user knows where their board went, and this app does not.
+    private func presentRegrantPanel(anchoredAt anchor: URL, boardName: String) -> URL? {
+        let panel = NSOpenPanel()
+        panel.canChooseDirectories = true
+        panel.canChooseFiles = false
+        panel.treatsFilePackagesAsDirectories = true
+        panel.allowsMultipleSelection = false
+        panel.directoryURL = anchor
+        panel.prompt = "Grant"
+        panel.message = "Choose “\(boardName)” to let this app open it."
+
+        guard panel.runModal() == .OK else { return nil }
+        return panel.url
+    }
+
    /// The ref of the window already showing the board at `url`, if any — matched through the store,
    /// which is identity-keyed, rather than through the path.
    private func boardRef(forBoardAt url: URL) -> BoardWindowRef? {
@@ -284,7 +284,22 @@ struct BoardWindowHost: View {
        // load rather than at attach because it carries the store; the controller installs it once,
        // whichever of the two arrives second.
        windowController.installTitlebarAccessory(
-            boardInfoTitlebarAccessory(store: store, recents: appModel.styleRecents, presentation: boardInfo)
+            boardInfoTitlebarAccessory(
+                store: store,
+                recents: appModel.styleRecents,
+                presentation: boardInfo,
+                // The cross-edition awareness line (12-editions.md ▸ Both editions installed), asked
+                // at each popover build rather than captured as a value: both facts behind it — the
+                // other edition's flag on the shared record, and whether that edition is still
+                // running — change while this window sits here, and neither is observable.
+                otherEditionNote: { [weak appModel] in
+                    guard let appModel else { return nil }
+                    return BoardEditionPresence.note(
+                        otherEditions: appModel.boardRegistry.otherEditionsFlaggedOpen(id: recordID),
+                        isRunning: BoardEditionPresence.isRunning
+                    )
+                }
+            )
        )

        // The board's customizable toolbar (03-board-ui.md ▸ Toolbar) — installed here for the
@@ -19,7 +19,7 @@ extension UTType {
 ///
 /// **It is self-describing twice over**, and both halves earn their keep:
 ///
-/// - `copyID` ties the pasteboard to a staging directory — `<Application Support>/…/Clipboard/<copyID>/`,
+/// - `copyID` ties the pasteboard to a staging directory — `<group container>/…/Clipboard/<copyID>/`,
 ///   the full folder snapshots a paste reproduces byte-for-byte from — and to a pending cut. It is
 ///   also the whole of "the snapshot survives relaunch exactly as long as the pasteboard still points
 ///   at it": a sweep keeps the one directory this id names and collects every other.
@@ -12,11 +12,17 @@ import os
 ///
 /// The pasteboard carries a small JSON manifest plus a plain-text rendering; the *content* — whole
 /// folder trees, attachments and strays and all — is **staged** under
-/// `<Application Support>/<bundle id>/Clipboard/<copyID>/`, so a paste reproduces the item
+/// `<group container>/Library/Application Support/Clipboard/<copyID>/`, so a paste reproduces the item
 /// byte-for-byte across boards rather than reconstructing it from a summary. The manifest's embedded
 /// `index.md` per entry is the fallback when a snapshot is missing, and a fallback paste is **loud**:
 /// a banner names exactly what was lost.
 ///
+/// **The store is shared by every installed edition** (12-editions.md ▸ Both editions installed, ruled
+/// 2026-07-29): the group container is one container, so ⌘C in base pastes full-fidelity in Pro. The
+/// lifecycle below is unchanged by that — both editions read the same machine-wide pasteboard, so both
+/// sweeps compute the same keep set — with one property made explicit: the sweep tolerates the sibling
+/// sweeping alongside it (`prune`).
+///
 /// ### The staging lifecycle, settled
 ///
 /// - **Eager**: the snapshot is taken at ⌘C/⌘X time, so a copy captures the source as it was at the
@@ -102,22 +108,24 @@ public final class ClipboardStore {

    private static let logger = Logger(subsystem: "dev.rzen.indie.Kanban", category: "clipboard")

-    /// `~/Library/Application Support/<bundle id>/Clipboard/`, beside the board registry — the same
-    /// container convention, for the same reason (02-architecture.md § Per-board app state, "App-wide
-    /// state has the same home").
+    /// `<group container>/Library/Application Support/Clipboard/`, beside the board registry — the
+    /// same home, for the same reason, and now the same *shared* home (12-editions.md ▸ Both editions
+    /// installed, ruled 2026-07-29):
+    ///
+    /// > The clipboard staging store homes in the group container beside the registry, so ⌘C in one
+    /// > edition pastes **full-fidelity** in the other — snapshot, attachments and all.
+    ///
+    /// Nothing about the lifecycle changes: both editions read the same pasteboard, so both sweeps
+    /// compute the same answer from the same input, and the degraded embedded-`index.md` fallback stays
+    /// for genuinely missing snapshots rather than being the structural cross-edition outcome.
    public static var defaultStagingRoot: URL {
-        let support = FileManager.default.urls(for: .applicationSupportDirectory, in: .userDomainMask).first
-            ?? URL(fileURLWithPath: NSHomeDirectory(), isDirectory: true)
-                .appendingPathComponent("Library/Application Support", isDirectory: true)
-        let bundleIdentifier = Bundle.main.bundleIdentifier ?? "dev.rzen.indie.Kanban"
-        return support
-            .appendingPathComponent(bundleIdentifier, isDirectory: true)
-            .appendingPathComponent("Clipboard", isDirectory: true)
+        AppGroup.stateDirectory.appendingPathComponent("Clipboard", isDirectory: true)
    }

    /// The app builds one of these with the system pasteboard and the real staging directory; a test
    /// passes its own of each, for the reason `BoardRegistry` takes a storage URL at all — injecting
-    /// them is how a suite stays out of Application Support *and* off the machine's one pasteboard.
+    /// them is how a suite stays out of the shared App Group container *and* off the machine's one
+    /// pasteboard.
    ///
    /// **The launch sweep is here** (04: "a sweep at launch and on each copy"): a fresh store reads
    /// the pasteboard once and collects every staged tree it no longer names, which is exactly the
@@ -508,14 +516,79 @@ public final class ClipboardStore {
        enqueue { await Self.prune(root, keeping: keep) }
    }

+    /// Where a tree goes to die: a hidden sibling inside the staging root, so a removal is **two
+    /// steps, the first of them atomic**.
+    ///
+    /// Hidden (`.`-prefixed) on purpose — `prune` lists with `.skipsHiddenFiles`, so this folder is
+    /// invisible to the sweep that owns it and can never be mistaken for a staged copy.
+    ///
+    /// `nonisolated` because `prune` is: the sweep runs off the main actor by design, and a constant
+    /// has no isolation to need.
+    private nonisolated static let sweepFolderName = ".sweeping"
+
+    /// The sweep, written to be safe against **the sibling edition sweeping the same directory at the
+    /// same time** (12-editions.md ▸ Both editions installed: "keep the sweep tolerant of the sibling
+    /// app's concurrent sweep — atomic removals, missing-entry = already swept").
+    ///
+    /// The staging root is now shared by every installed edition, and each edition sweeps on its own
+    /// launches, activations, copies and pastes. Both compute the *same* answer — the keep set is the
+    /// one `copyID` the machine-wide pasteboard names — so they never disagree about what should go;
+    /// what they can do is arrive at the same doomed tree together. Two properties make that a
+    /// non-event:
+    ///
+    /// 1. **The claim is a rename, and a rename is atomic.** `moveItem` into `.sweeping/` either
+    ///    happens or does not; exactly one sweeper can win it, and the loser's failure is the signal
+    ///    that somebody else owns the tree now. Deleting in place would instead have two processes
+    ///    walking one directory tree as it disappeared under them — the case where a half-removed tree
+    ///    is briefly *visible*, which is the only way a concurrent sweep could corrupt a paste.
+    /// 2. **A missing entry means already swept, never an error.** Every failure here is swallowed:
+    ///    the listing is stale by the time it is walked, and a tree that vanished between the two is
+    ///    precisely the outcome asked for.
+    ///
+    /// Leftovers in `.sweeping/` are collected on the next pass. A crash between the rename and the
+    /// delete therefore costs disk until the next sweep, which is the same guarantee the staging store
+    /// already gives about its own orphans.
    private nonisolated static func prune(_ root: URL, keeping keep: String?) async {
+        let sweepFolder = root.appendingPathComponent(sweepFolderName, isDirectory: true)
+
        guard let entries = try? FileManager.default.contentsOfDirectory(
            at: root,
            includingPropertiesForKeys: nil,
            options: [.skipsHiddenFiles]
        ) else { return }
+
+        var claimed: [URL] = []
        for entry in entries where entry.lastPathComponent != keep {
-            try? FileManager.default.removeItem(at: entry)
+            // Created lazily: a sweep with nothing to collect must not leave a folder behind as proof
+            // it ran.
+            if claimed.isEmpty {
+                try? FileManager.default.createDirectory(at: sweepFolder, withIntermediateDirectories: true)
+            }
+            let claim = sweepFolder.appendingPathComponent(UUID().uuidString, isDirectory: true)
+            guard (try? FileManager.default.moveItem(at: entry, to: claim)) != nil else {
+                // Gone, or the sibling's sweep claimed it first. Either way it is not ours to delete
+                // and nothing is wrong.
+                continue
+            }
+            claimed.append(claim)
+        }
+
+        for claim in claimed {
+            try? FileManager.default.removeItem(at: claim)
+        }
+
+        // Anything a previous pass claimed and did not finish — including the sibling app's, whose
+        // claims are as much ours to collect as our own, since a claimed tree is unreachable by
+        // either. Best-effort, and an empty or missing folder is nothing to do.
+        if let stragglers = try? FileManager.default.contentsOfDirectory(
+            at: sweepFolder,
+            includingPropertiesForKeys: nil,
+            options: []
+        ) {
+            for straggler in stragglers {
+                try? FileManager.default.removeItem(at: straggler)
+            }
+            try? FileManager.default.removeItem(at: sweepFolder)
        }
    }

@@ -92,6 +92,17 @@ struct RestoreBootstrapView: View {
                    path: record.lastKnownPath,
                    message: "This board is unavailable. Its volume may be offline, or it may have been moved or deleted."
                )
+            case .needsReopen:
+                // Effectively unreachable — this edition can only have flagged a board open by having
+                // opened it, which needed a grant — and deliberately quiet if it ever happens.
+                //
+                // **No launch failure and no panel.** A modal grant panel at launch is exactly the
+                // "launch-time modal chain" 02 § Launch and window lifecycle rules out, and a failure
+                // row would put fail-fast's warning tone over a board that is *fine*: welcome appears
+                // (nothing restored), and this board's own row already carries the re-grant caption
+                // and the one click that resolves it (12-editions.md ▸ Distribution). That row is the
+                // surface, so nothing is silently dropped.
+                Self.logger.error("a flagged board is awaiting this edition's grant; left for its welcome row")
            }
        }

@@ -27,7 +27,7 @@ import os
 ///
 /// ### Reveal in Finder, and how fresh the list is
 ///
-/// 09 keeps the Application Support store honest with "a **Reveal in Finder** affordance in the
+/// 09 keeps the app-side store honest with "a **Reveal in Finder** affordance in the
 /// template chooser": the button beside the header, which **creates the store and then reveals it**
 /// (`TemplateEngine.createUserStore`) — the store's two minters are Save as Template and this, so a
 /// user who has never saved one still gets a folder to drop a board into rather than a Finder window
@@ -285,7 +285,7 @@ struct TemplateChooserView: View {
    ///
    /// A store that cannot be created is logged and *still* revealed at its parent by
    /// `activateFileViewerSelecting`, which is the honest failure: something is wrong with
-    /// Application Support, and the user is standing where they can see it.
+    /// the app-side store, and the user is standing where they can see it.
    private func revealUserStore() {
        let store = TemplateEngine.userStore
        do {
@@ -95,7 +95,7 @@ enum TemplateEngine {

    // MARK: - Where templates live

-    /// The store folder's name in both locations — the bundle's and Application Support's.
+    /// The store folder's name in both locations — the bundle's and the App Group container's.
    static let storeFolderName = "Templates"

    /// The bundled store: `<app bundle>/Contents/Resources/Templates/`, holding one board folder per
@@ -105,23 +105,27 @@ enum TemplateEngine {
        Bundle.main.resourceURL?.appendingPathComponent(storeFolderName, isDirectory: true)
    }

-    /// The user store: `<Application Support>/<bundle id>/Templates/`, beside the board registry and
-    /// the clipboard staging directory — 09's settled location ("Application Support … inside the
-    /// app container — friction-free sandbox writes, no location ceremony"), spelled the way every
-    /// other app-wide store in this app spells it (`ClipboardStore.defaultStagingRoot`,
-    /// `BoardRegistry`; 02-architecture.md § Per-board app state, "App-wide state has the same home").
+    /// The user store: `Templates/` in the **shared App Group container**, beside the board registry
+    /// and the clipboard's staging store (09-templates.md ▸ Save as Template ▸ Storage, re-homed
+    /// 2026-07-29; 02-architecture.md § Per-board app state, "App-wide state has the same home").
+    ///
+    /// > **templates cross editions**: a template saved in base appears in Pro's chooser, honoring 12's
+    /// > never-an-empty-home-screen promise (templates are plain board folders — no per-edition
+    /// > semantics, no bookmark grant ceremony; the group container is directly writable by every
+    /// > edition).
+    ///
+    /// That last clause is why this store needs none of the machinery the registry does: a template is
+    /// a folder inside a container both editions can write, so there is no bookmark to mint and nothing
+    /// to grant — the cross-sandbox caveat that gives `BoardRecord` its per-edition grant slots simply
+    /// does not arise. Spelled through `AppGroup.stateDirectory` like every other app-wide store
+    /// (`ClipboardStore.defaultStagingRoot`, `BoardRegistry.defaultStorageURL`), so all three move
+    /// together if the home ever does.
    ///
    /// **Named, never created here.** Discovery of a store that does not exist is an empty list, not
    /// a directory the app made on the off-chance: the store is minted by the first Save as Template,
    /// and by Reveal in Finder, both of which are 09's other cards.
    static var userStore: URL {
-        let support = FileManager.default.urls(for: .applicationSupportDirectory, in: .userDomainMask).first
-            ?? URL(fileURLWithPath: NSHomeDirectory(), isDirectory: true)
-                .appendingPathComponent("Library/Application Support", isDirectory: true)
-        let bundleIdentifier = Bundle.main.bundleIdentifier ?? "dev.rzen.indie.Kanban"
-        return support
-            .appendingPathComponent(bundleIdentifier, isDirectory: true)
-            .appendingPathComponent(storeFolderName, isDirectory: true)
+        AppGroup.stateDirectory.appendingPathComponent(storeFolderName, isDirectory: true)
    }

    // MARK: - Discovery
@@ -445,7 +449,7 @@ enum TemplateEngine {
    ///
    /// **The store's two minters are Save as Template and Reveal in Finder** (see `userStore`, which
    /// only names it): a store that exists because the app made it on the off-chance would be an
-    /// empty folder in Application Support for a user who never used the feature, while a Reveal
+    /// empty folder in the shared container for a user who never used the feature, while a Reveal
    /// that opened nothing — or a save that failed because its own home was missing — would be the
    /// app being pedantic about a directory it owns.
    @discardableResult
@@ -92,18 +92,22 @@ enum LaunchPlan: Equatable, Sendable {
 ///
 /// ### What the flag also switches off
 ///
-/// **The registry moves into the scratch directory** with the board. Without that, every audit run
-/// would stamp a temp folder into the user's real recents list (`BoardRegistry.defaultStorageURL`,
-/// in Application Support), where it would sit for good as an unavailable row pointing at a
-/// directory that no longer exists. Tying it to the same flag rather than to a second argument is
-/// deliberate: the two are one decision — "this launch is synthetic" — and a second argument is a
-/// second chance to apply only half of it.
+/// **The registry and the clipboard's staging store move into the scratch directory** with the board.
+/// Without that, every audit run would stamp a temp folder into the user's real recents list
+/// (`BoardRegistry.defaultStorageURL`), where it would sit for good as an unavailable row pointing at a
+/// directory that no longer exists — and its launch sweep would collect the user's real staged copy
+/// (`ClipboardStore.defaultStagingRoot`). Both of those homes are now the **shared App Group
+/// container** (12-editions.md ▸ Distribution, ruled 2026-07-29), so each of those side effects would
+/// land on the sibling edition as well as this one. Tying them to the same flag rather than to separate
+/// arguments is deliberate: they are one decision — "this launch is synthetic" — and a second argument
+/// is a second chance to apply only half of it.
 ///
 /// The honest residual: `UserDefaults` is **not** redirected, so an audit run can still write the
-/// three app-wide scalars (`AppPreferences`) into the real domain. They are a window size, a restore
-/// toggle this launch never consults, and the quick-style recents list — no documents, nothing
-/// destructive, and redirecting a defaults domain from inside the process is not something the
-/// platform actually supports. It is stated rather than fixed.
+/// three app-wide scalars (`AppPreferences`) into the real domain — the group's shared suite since the
+/// same ruling. They are a window size, a restore toggle this launch never consults, and the
+/// quick-style recents list — no documents, nothing destructive, and redirecting a defaults domain from
+/// inside the process is not something the platform actually supports. It is stated rather than
+/// fixed.
 enum UITestLaunch {

    private static let logger = Logger(subsystem: "dev.rzen.indie.Kanban", category: "ui-test-launch")
@@ -208,12 +212,21 @@ enum UITestLaunch {
            .appendingPathComponent("LaneworkUITestFixture", isDirectory: true)
    }

-    /// Where the fixture launch's registry lives — beside the board rather than in Application
-    /// Support, which is the whole point (see the type's note).
+    /// Where the fixture launch's registry lives — beside the board rather than in the shared App
+    /// Group container, which is the whole point (see the type's note).
    static var registryStorageURL: URL {
        scratchRoot.appendingPathComponent("board-registry.json", isDirectory: false)
    }

+    /// Where the fixture launch's clipboard snapshots live, on the registry's terms and now for a
+    /// sharper reason: the real staging root moved into the **shared** App Group container
+    /// (12-editions.md ▸ Both editions installed), so an audit run's launch sweep would otherwise
+    /// collect the developer's own staged copy — and the sibling edition's, since there is only one
+    /// store now. Redirected by the same flag, because it is the same one decision.
+    static var clipboardStagingRoot: URL {
+        scratchRoot.appendingPathComponent("Clipboard", isDirectory: true)
+    }
+
    /// A fixture board's own folder. `.kanban`-suffixed because a board the app made through the
    /// ordinary create path is a document, and the audit should be looking at the shape a user's
    /// board actually has (01-storage-format.md § Document packaging).
@@ -230,8 +243,10 @@ enum UITestLaunch {
        fixtureBoardURL(for: .standard)
    }

-    /// Wipes and recreates the scratch root, and answers the registry URL to build the app model
-    /// with. Called once, from `KanbanApp.init()`, **before** the model reads its registry.
+    /// Wipes and recreates the scratch root, and answers the registry URL for the caller's convenience.
+    /// Called once, from `KanbanApp.init()`, **before** the model reads its registry — which is also why
+    /// the return value is discardable: that caller now names both redirected homes explicitly
+    /// (`registryStorageURL`, `clipboardStagingRoot`) rather than taking one of them from here.
    ///
    /// **Wiped rather than reused**: every audit test launches its own app instance, and an audit is
    /// only meaningful against a board whose contents the test knows — a previous run's leftovers
@@ -40,10 +40,18 @@ struct WelcomeRow: Identifiable, Equatable {
    let icon: String?
    let iconColor: String?

-    /// Where the board is **now**, or `nil` when its bookmark no longer resolves. The single source
+    /// Where the board is **now**, or `nil` when this edition cannot reach it. The single source
    /// of the row's availability: Open and Reveal need a URL, and an orphan has none.
    let url: URL?

+    /// Where the re-grant panel starts for a row whose only grant another edition minted
+    /// (`RecentBoard.needsReopen`; 12-editions.md ▸ Distribution) — `nil` on every other row.
+    ///
+    /// It is what makes this row's Open live while `url` is `nil`: the board is *there*, and one click
+    /// plus Grant is all that stands between the user and it. Reveal in Finder stays disabled, because
+    /// revealing a folder is a read this app has not been granted either.
+    let regrantAnchor: URL?
+
    /// The containing folder, for the row's location line — Xcode's welcome shows where a project
    /// lives, not its own path repeated under its name. Home-abbreviated where it can be.
    let location: String
@@ -58,10 +66,14 @@ struct WelcomeRow: Identifiable, Equatable {

    var isAvailable: Bool { url != nil }

-    /// Open and Reveal in Finder both need somewhere to go; Forget is deliberately not here, because
-    /// it is enabled on every row — an orphan the user can never open is exactly the row that most
-    /// needs erasing (02 § Graceful orphaning: "recents surface it as unavailable with Forget").
-    var canOpen: Bool { isAvailable }
+    /// Whether this row is waiting for this edition's grant rather than being genuinely orphaned.
+    var needsReopen: Bool { regrantAnchor != nil }
+
+    /// Open needs somewhere to go **or something to grant**; Reveal in Finder needs the former only.
+    /// Forget is deliberately not here, because it is enabled on every row — an orphan the user can
+    /// never open is exactly the row that most needs erasing (02 § Graceful orphaning: "recents
+    /// surface it as unavailable with Forget").
+    var canOpen: Bool { isAvailable || needsReopen }
    var canReveal: Bool { isAvailable }

    /// The row's third line — one line, so the three states are alternatives rather than a stack.
@@ -74,12 +86,20 @@ struct WelcomeRow: Identifiable, Equatable {
        case counts(lanes: Int?, cards: Int?)
        /// The bookmark no longer resolves (02 § Graceful orphaning).
        case unavailable
+        /// This edition has never been granted the board another edition minted the record for
+        /// (12-editions.md ▸ Distribution) — the *reopen* state, which is not orphaning: the board is
+        /// there, and one click opens the panel that grants it.
+        case needsReopen
        /// Fail-fast's specifics, from the open or restore that failed.
        case failed(String)
    }

    var caption: Caption {
        if let failure { return .failed(failure) }
+        // Before `unavailable`, because the two are told apart by *why* there is no URL and this one
+        // is the reachable case: an orphan's caption offering to grant access would be a promise the
+        // app cannot keep, and this row wearing the orphan's caption would read as a loss it is not.
+        if needsReopen { return .needsReopen }
        if url == nil { return .unavailable }
        return .counts(lanes: laneCount, cards: cardCount)
    }
@@ -143,6 +163,7 @@ struct WelcomeRow: Identifiable, Equatable {
                icon: record.icon,
                iconColor: record.iconColor,
                url: recent.url,
+                regrantAnchor: recent.regrantAnchor,
                location: location(of: recent.url?.path ?? record.lastKnownPath),
                laneCount: record.laneCount,
                cardCount: record.cardCount,
@@ -244,12 +244,13 @@ struct WelcomeView: View {

    // MARK: Actions

-    /// Opens a row's board. Welcome closes itself on the way in — that is the board window host's
-    /// job ("Opening a board from welcome closes welcome"), not this view's, because the close has to
-    /// wait for the load to actually succeed.
+    /// Opens a row's board — through `AppModel.open(_:)`, which owns the two ways a row can lead to
+    /// one (an available URL, or the re-grant panel a cross-edition row needs first). Welcome closes
+    /// itself on the way in — that is the board window host's job ("Opening a board from welcome
+    /// closes welcome"), not this view's, because the close has to wait for the load to actually
+    /// succeed.
    private func open(_ row: WelcomeRow) {
-        guard let url = row.url else { return }
-        appModel.openBoard(at: url)
+        appModel.open(row)
    }

    private func reveal(_ row: WelcomeRow) {
@@ -320,8 +321,9 @@ private struct RecentBoardRow: View {
        }
        .padding(.vertical, BoardMetrics.em(0.3, bodyPointSize: WelcomeView.pointSize))
        // Dimmed when the board cannot be reached — the row stays, with Forget, rather than
-        // disappearing (02 § Graceful orphaning).
-        .opacity(row.isAvailable ? 1 : 0.55)
+        // disappearing (02 § Graceful orphaning). A cross-edition row is *not* dimmed: it opens on one
+        // click like any other, and dimming it would advertise a loss that has not happened.
+        .opacity(row.canOpen ? 1 : 0.55)
        .accessibilityElement(children: .combine)
    }

@@ -363,6 +365,14 @@ private struct RecentBoardRow: View {
                .font(.caption)
                .foregroundStyle(.secondary)
                .lineLimit(1)
+        case .needsReopen:
+            // Not a warning tone: nothing is wrong and nothing is lost — this board came from the
+            // other edition's list and needs one grant (12-editions.md ▸ Distribution). The words say
+            // what the click will do, since the click is the whole remedy.
+            Label("Open once to grant access", systemImage: "hand.raised")
+                .font(.caption)
+                .foregroundStyle(.secondary)
+                .lineLimit(1)
        case let .failed(message):
            // The warning tint, and the whole of fail-fast's specifics — this row *is* the failure
            // surface (02 § Launch and window lifecycle).
@@ -385,7 +395,10 @@ private struct RecentBoardRow: View {
 /// turned off and then turns it back on.
 struct SettingsView: View {

-    @AppStorage(AppPreferences.restoreOpenBoardsAtLaunchKey)
+    /// `store:` named explicitly, and it has to be: the key lives in the group's shared suite
+    /// (`AppPreferences`), and `@AppStorage`'s default domain is `.standard` — a different one. A
+    /// toggle bound to the wrong domain would write a preference the launch flow never reads.
+    @AppStorage(AppPreferences.restoreOpenBoardsAtLaunchKey, store: AppGroup.defaults)
    private var restoreOpenBoardsAtLaunch = true

    var body: some View {
@@ -8,5 +8,17 @@
 	<true/>
 	<key>com.apple.security.files.bookmarks.app-scope</key>
 	<true/>
+	<!-- The family App Group (12-editions.md ▸ Distribution, ruled 2026-07-29). Every edition
+	     declares this same group id, and the board registry with its app-wide peers — the
+	     clipboard's staging store, the shared defaults suite — homes in its container from day
+	     one, so a paying upgrader launches Pro onto their own recents rather than an empty
+	     screen. **It must be in base's shipped entitlements**: base ships first, and an edition
+	     that joined the group later would have a migration to do. Security-scoped bookmarks are
+	     the stated exception — they never cross sandboxes, group or not, which is why each
+	     edition holds its own grant slot on the shared record. -->
+	<key>com.apple.security.application-groups</key>
+	<array>
+		<string>group.dev.rzen.indie.Kanban</string>
+	</array>
 </dict>
 </plist>
@@ -41,14 +41,21 @@ struct KanbanApp: App {
    private let launchPlan: LaunchPlan

    init() {
-        // Read first, because it decides *which registry file the model is built with* — a fixture
-        // launch keeps its recents in the scratch directory rather than in the user's real one.
+        // Read first, because it decides *which app-side state the model is built over* — a fixture
+        // launch keeps its recents and its clipboard snapshots in the scratch directory rather than in
+        // the shared App Group container.
        let isUITestFixtureLaunch = UITestLaunch.isFixtureLaunch
-        let registryStorageURL = isUITestFixtureLaunch
-            ? UITestLaunch.prepareScratchDirectory()
-            : BoardRegistry.defaultStorageURL
-
-        let model = AppModel(registryStorageURL: registryStorageURL)
+        if isUITestFixtureLaunch {
+            UITestLaunch.prepareScratchDirectory()
+        }
+        let model = AppModel(
+            registryStorageURL: isUITestFixtureLaunch
+                ? UITestLaunch.registryStorageURL
+                : BoardRegistry.defaultStorageURL,
+            clipboardStagingRoot: isUITestFixtureLaunch
+                ? UITestLaunch.clipboardStagingRoot
+                : ClipboardStore.defaultStagingRoot
+        )
        _appModel = State(initialValue: model)
        launchPlan = LaunchPlan.decide(
            isUITestFixtureLaunch: isUITestFixtureLaunch,
@@ -0,0 +1,189 @@
+import Foundation
+import os
+
+/// **The family App Group** — where every edition's app-side state lives (12-editions.md
+/// § Distribution, ruled 2026-07-29; 02-architecture.md § Per-board app state).
+///
+/// ### Why a shared container at all
+///
+/// Boards are files, so they need no migration between editions — but the *app-side* state around
+/// them (the recents list, per-board frames, the quick-style row, the clipboard's staged snapshot)
+/// is app-private, and per-app-private means an upgrader lands on an empty home screen. So every
+/// edition declares one group — `group.dev.rzen.indie.Kanban` — and homes that state in its
+/// container **from day one**: base 2.0 ships with the entitlement, Pro's first release joins the
+/// same group, Teams later does too, and at no point is there a migration or an ordering dependency
+/// between them.
+///
+/// ### The one thing that cannot be shared
+///
+/// **Security-scoped bookmarks never cross sandboxes** — App Group or not, a bookmark is minted for
+/// one app's sandbox and resolves in that one only. So the registry record is *common* except for
+/// a per-edition **grant slot** keyed by bundle id (`BoardRecord.grants`), and a record whose only
+/// grant another edition minted reads as unavailable-until-reopened. Open-now flags are keyed the
+/// same way, for the same shape of reason: an edition restores the boards *it* had open.
+///
+/// ### It degrades rather than fails
+///
+/// `containerURL(forSecurityApplicationGroupIdentifier:)` answers `nil` when the group is not
+/// provisioned for the running binary — a unit-test host without the capability, a locally signed
+/// build before the group is registered on the team. Every path here falls back to the *previous*
+/// per-edition Application Support home in that case, so nothing depends on provisioning to work:
+/// state simply stops being shared, which is exactly the old behaviour.
+public enum AppGroup {
+
+    /// The group id every edition declares, verbatim (12-editions.md ▸ Distribution). It is
+    /// deliberately the *family* name rather than an edition's: Pro and Teams declare this same
+    /// string, and a future edition's bundle id joins with no further ceremony.
+    public static let identifier = "group.dev.rzen.indie.Kanban"
+
+    private static let logger = Logger(subsystem: "dev.rzen.indie.Kanban", category: "app-group")
+
+    // MARK: - Edition identity
+
+    /// Base's bundle id — also the fallback when `Bundle.main` has none, which is a test host's
+    /// case and never a shipped app's.
+    public static let baseEditionID = "dev.rzen.indie.Kanban"
+
+    /// Pro's bundle id (12 ▸ Targets, ruled 2026-07-27). Named here as well as in
+    /// `ProEdition.bundleIdentifier` because *base* has to know it: the popover's awareness line and
+    /// the grant-slot keying are shared-tree code that must be able to name the other edition
+    /// without compiling any of it.
+    public static let proEditionID = "dev.rzen.indie.KanbanPro"
+
+    /// Which edition is running — the key every per-edition slot on a shared record is stored under.
+    ///
+    /// Read from `Bundle.main` rather than declared per target, which is what keeps this file free of
+    /// any edition conditional: the binary already knows which app it is.
+    public static var editionID: String {
+        Bundle.main.bundleIdentifier ?? baseEditionID
+    }
+
+    /// The user-facing name of an edition, for the popover's awareness line ("Also open in Lanework
+    /// Pro"). `nil` for a bundle id this build has never heard of — a future edition's, or a stale
+    /// slot left by something else — because inventing a name for it would be worse than saying
+    /// nothing, and the line's whole posture is that it never lies.
+    public static func editionDisplayName(_ bundleID: String) -> String? {
+        switch bundleID {
+        case baseEditionID: "Lanework"
+        case proEditionID: "Lanework Pro"
+        default: nil
+        }
+    }
+
+    // MARK: - The container
+
+    /// The group container, or `nil` when the running binary has no such capability.
+    ///
+    /// Not cached: the answer is a property of the process's entitlements and cannot change within
+    /// a launch, but the call is a cheap lookup and a cached `nil` from an early read (before the
+    /// container has been created for the first time) is the sort of staleness this file should not
+    /// invent.
+    public static var containerURL: URL? {
+        FileManager.default.containerURL(forSecurityApplicationGroupIdentifier: identifier)
+    }
+
+    /// Where every app-side file store lives — the registry, the clipboard's staging snapshots, and
+    /// whatever joins them.
+    ///
+    /// In a shipped app this is `productionStateDirectory`. **In a unit-test host it is a scratch
+    /// directory** (`isUnitTestHost`), which is not a nicety: the real container is shared with the
+    /// sibling edition and with the developer's own running copy, so a suite that used it would be
+    /// sweeping real staged clipboard copies and rewriting a real recents list.
+    public static var stateDirectory: URL {
+        isUnitTestHost ? unitTestStateDirectory : productionStateDirectory
+    }
+
+    /// What a shipped app uses: `<group container>/Library/Application Support/`.
+    ///
+    /// **No bundle-id subfolder**, unlike the per-edition home this replaces — that subfolder was
+    /// exactly what kept two editions from seeing one list, and its absence is the whole feature.
+    /// `Library/Application Support` is kept as the path *inside* the container for Apple's
+    /// convention rather than for any behaviour: the container is the app's either way.
+    ///
+    /// Falls back to `perEditionSupportDirectory` when there is no group container (see the type's
+    /// note): unshared, but working.
+    public static var productionStateDirectory: URL {
+        guard let containerURL else {
+            logger.debug("no group container for \(identifier, privacy: .public); using the per-edition home")
+            return perEditionSupportDirectory
+        }
+        return containerURL
+            .appendingPathComponent("Library", isDirectory: true)
+            .appendingPathComponent("Application Support", isDirectory: true)
+    }
+
+    /// The pre-2.0 home — `~/Library/Application Support/<bundle id>/`, inside this edition's own
+    /// sandbox container. Kept as the fallback above and as the home of anything deliberately *not*
+    /// shared.
+    public static var perEditionSupportDirectory: URL {
+        let support = FileManager.default.urls(for: .applicationSupportDirectory, in: .userDomainMask).first
+            ?? URL(fileURLWithPath: NSHomeDirectory(), isDirectory: true)
+                .appendingPathComponent("Library/Application Support", isDirectory: true)
+        return support.appendingPathComponent(editionID, isDirectory: true)
+    }
+
+    // MARK: - Keeping the suites out of it
+
+    /// Whether this process is hosting a unit-test bundle.
+    ///
+    /// ### Why the app has to know
+    ///
+    /// The unit-test host **is the app** (`KanbanTests` and `KanbanProTests` are hosted bundles), so
+    /// `KanbanApp.init()` runs for real on every test launch and builds an `AppModel` over whatever
+    /// the defaults resolve to. Every *object* a test constructs takes its storage by injection — that
+    /// is the seam, and it is untouched — but the host's own launch has no injection point, and after
+    /// the 2026-07-29 ruling the thing it would reach for is a container shared with the sibling
+    /// edition and with the developer's running copy. Its launch sweep would collect real staged
+    /// clipboard trees; its `refreshRecents()` would resolve, refresh and rewrite real records.
+    ///
+    /// So the *default* moves for a test host, which is the one place a default can be wrong in a way
+    /// injection cannot fix.
+    ///
+    /// ### Why this variable and not a launch flag
+    ///
+    /// `UITestLaunch.fixtureFlag` is the flag-shaped answer and remains the right one for the UI
+    /// suites, which launch the app themselves and can pass arguments. A *unit*-test host is launched
+    /// by the test runner, which passes nothing of ours — but it does set these variables, and it has
+    /// set them for as long as XCTest has existed. Three spellings are checked because Apple has used
+    /// each at some point and a missed one would silently mean "not a test".
+    ///
+    /// It cannot fire in a shipped app: nothing sets these but a test runner.
+    public static var isUnitTestHost: Bool {
+        let environment = ProcessInfo.processInfo.environment
+        return environment["XCTestConfigurationFilePath"] != nil
+            || environment["XCTestBundlePath"] != nil
+            || environment["XCTestSessionIdentifier"] != nil
+    }
+
+    /// The scratch home a test host uses instead. Inside the app's own container (`NSTemporaryDirectory`
+    /// sandboxes there), so nothing outside this app can see it and the OS reclaims it.
+    ///
+    /// One fixed folder rather than one per run: the suites do not depend on it being empty — they
+    /// inject their own paths for anything they assert on — and a stable name keeps it inspectable when
+    /// something writes there that should not have.
+    public static var unitTestStateDirectory: URL {
+        URL(fileURLWithPath: NSTemporaryDirectory(), isDirectory: true)
+            .appendingPathComponent("LaneworkUnitTestState", isDirectory: true)
+    }
+
+    // MARK: - The shared defaults suite
+
+    /// The group's shared `UserDefaults` suite — where app-side state that is a *scalar* lives
+    /// (02-architecture.md § Per-board app state: "or the group's shared `UserDefaults` suite where
+    /// a scalar fits").
+    ///
+    /// `UserDefaults(suiteName:)` answers `nil` only for a suite name equal to the app's own bundle
+    /// id, which this never is; `.standard` is the fallback anyway, for the reason every fallback
+    /// here exists — an unshared preference is a papercut, an unreadable one is a bug.
+    ///
+    /// Without the entitlement the suite is an ordinary named domain rather than a shared one, so
+    /// this works unprovisioned too: the values are simply this edition's alone.
+    ///
+    /// A **test host gets its own suite name** for `isUnitTestHost`'s reason applied to preferences: a
+    /// suite that read and wrote the real one would be reading and writing the developer's quick-style
+    /// row and window size, which is the objection `StyleModelTests` already states about
+    /// `UserDefaults.standard`.
+    public static var defaults: UserDefaults {
+        UserDefaults(suiteName: isUnitTestHost ? "\(identifier).unit-tests" : identifier) ?? .standard
+    }
+}
@@ -55,35 +55,80 @@ public struct WindowFrame: Codable, Sendable, Equatable {
 /// One known board: everything the app keeps *about* a board that must never be written *into* it.
 ///
 /// **Files-first is absolute** (02-architecture.md § Per-board app state): no frontmatter key, no
-/// sidecar, no xattr — this record lives wholly in Application Support, which is also why two
-/// machines sharing a board through a remote each keep their own (push-on-commit and window frames
-/// are genuinely per-machine choices).
+/// sidecar, no xattr — this record lives wholly in the shared App Group container, which is also why
+/// two machines sharing a board through a remote each keep their own (push-on-commit and window
+/// frames are genuinely per-machine choices).
 ///
 /// The **bookmark is the identity**; `lastKnownPath` is display text and nothing else. Matching an
 /// opened folder to its record resolves the bookmark and compares file identity, so a board renamed
 /// or moved on the same volume keeps its settings and its place in recents.
 ///
+/// ### One record, shared by every edition — with two per-edition fields
+///
+/// The record lives in the family App Group container (`AppGroup`), so base, Pro and later Teams all
+/// read and write the same one: an upgrader's recents, frames and settings are simply *there*
+/// (12-editions.md ▸ Distribution, ruled 2026-07-29). Two fields cannot be common, and both are
+/// keyed by bundle id for the same reason:
+///
+/// - **`grants`** — security-scoped bookmarks never cross sandboxes (12: "minted per sandbox, App
+///   Group or not"), so each edition holds its own. A record whose only grant another edition minted
+///   resolves *unavailable-until-reopened* (`RecentBoard.needsReopen`) and its first click runs an
+///   open panel pre-anchored at `lastKnownPath`.
+/// - **`openNow`** — "an edition restores only the boards *it* had open" (12; 02 § Launch and window
+///   lifecycle), which is also what lets the board popover say "Also open in Lanework Pro" from the
+///   *other* edition's flag.
+///
+/// Everything else here is common, deliberately: a window frame, a cached title, a lane count and a
+/// push-on-commit choice are facts about the board and this machine, not about which app is looking.
+///
 /// ### Evolving this struct
 ///
-/// The synthesized `Codable` conformance rejects a file missing any non-optional key, and
-/// `BoardRegistry` responds to a rejected file by quarantining it — every record lost. So **a key
-/// added here must be optional or have a decoding default**, or the addition silently empties every
-/// existing user's recents on upgrade. That policy, not a version field, is what keeps this format
-/// readable across releases.
+/// `BoardRegistry` responds to a file it cannot decode by quarantining it — every record lost. So
+/// **a key added here must be optional or have a decoding default**, or the addition silently
+/// empties every existing user's recents on upgrade. That policy, not a version field, is what keeps
+/// this format readable across releases; `init(from:)` below applies it by hand for the keys that
+/// arrived with the App Group, and keeps the four founding keys required exactly as they were.
 public struct BoardRecord: Codable, Sendable, Equatable, Identifiable {
    public let id: UUID

-    /// The security-scoped bookmark — **the board's identity**, refreshed on every open. Empty only
-    /// in the degenerate case where the system refused to make one at all, which is a record born
-    /// orphaned: it shows in recents with Forget and never matches an open.
-    public var bookmark: Data
+    /// The per-edition security-scoped grant slots — **the board's identity, per sandbox** — keyed by
+    /// bundle id and refreshed on every open *by that edition*. Empty for an edition means "this app
+    /// has never been granted this board", which is the unavailable-until-reopened state and not an
+    /// error.
+    ///
+    /// A record with no grants at all is the degenerate case where the system refused to mint one:
+    /// born orphaned, shown in recents with Forget, never matching an open.
+    public var grants: [String: Data]
+
+    /// Per-edition open-now flags, keyed by bundle id — see `isOpen(inEdition:)` for what the flag
+    /// *means*, which is unchanged; only its keying is new.
+    public var openNow: [String: Bool]
+
+    /// The pre-App-Group single-grant key (`bookmark`), decoded and **never re-encoded**.
+    ///
+    /// Its whole life is `BoardRegistry.adoptLegacyKeys()`: a record written before the grant slots
+    /// existed has one bookmark, minted by whichever edition wrote it — and since only base existed
+    /// then, adopting it as the *running* edition's slot is the coherent reading. Adopted in memory
+    /// at load and gone from the file on the first save, which is why nothing else here ever looks
+    /// at it.
+    public private(set) var legacyBookmark: Data?
+
+    /// The pre-App-Group single open-now key (`isOpenNow`), on the same terms as `legacyBookmark`.
+    public private(set) var legacyOpenNow: Bool?

    /// Last-known title or folder name, for the recents row. Display only.
    public var displayName: String

    /// Where the board was last seen, for the recents row when the bookmark no longer resolves and
-    /// there is nothing else to show. **Never used for matching** — that is the bookmark's job, and
-    /// a path that matched would reintroduce exactly the identity-by-string bug this design excludes.
+    /// there is nothing else to show.
+    ///
+    /// **Not how a board is identified** — that is the grant slot's job, and a path used as the primary
+    /// key would reintroduce exactly the identity-by-string bug this design excludes. It has precisely
+    /// one narrow other use, which 12-editions.md itself nominates: for a record only *another* edition
+    /// holds a grant for, this is the open panel's anchor and the only locator this app has, so
+    /// `BoardRegistry.indexOfRecord(matching:)` falls back to it — after identity has failed, and only
+    /// against records holding no grant of ours. Without that, granting a board in the second edition
+    /// would fork the shared record in two.
    public var lastKnownPath: String

    public var lastOpened: Date
@@ -136,21 +181,6 @@ public struct BoardRecord: Codable, Sendable, Equatable, Identifiable {
    /// time — never here.
    public var iconColor: String?

-    /// Whether this board's window is open **right now** — the restoration set, as a live marker
-    /// rather than an at-quit write (02-architecture.md § Launch and window lifecycle, settled).
-    ///
-    /// Set when the board's window opens, cleared on *user-initiated* close; quit's teardown
-    /// deliberately leaves it standing, because the boards open at quit are by definition the ones
-    /// to restore. **Crash recovery falls out for free**: after a crash the flags describe what was
-    /// open at crash time, so the next launch restores exactly that — no separate recovery logic, no
-    /// once-at-quit stamp to race teardown or miss when the app dies.
-    ///
-    /// **Optional because every key here must be** (see Evolving this struct above): a registry file
-    /// written before this key existed decodes with `nil`, which reads as "not open" and costs the
-    /// user nothing. A non-optional `Bool` would have quarantined every existing file on upgrade and
-    /// emptied everyone's recents.
-    public var isOpenNow: Bool?
-
    /// Whether committing also pushes (07-sync-collab.md). Off by default: pushing is a decision,
    /// not a side effect.
    public var pushOnCommit: Bool
@@ -162,7 +192,7 @@ public struct BoardRecord: Codable, Sendable, Equatable, Identifiable {

    public init(
        id: UUID = UUID(),
-        bookmark: Data,
+        grants: [String: Data] = [:],
        displayName: String,
        lastKnownPath: String,
        lastOpened: Date,
@@ -170,14 +200,14 @@ public struct BoardRecord: Codable, Sendable, Equatable, Identifiable {
        cardCount: Int? = nil,
        windowFrame: WindowFrame? = nil,
        cardWindowFrames: [String: WindowFrame]? = nil,
-        isOpenNow: Bool? = nil,
+        openNow: [String: Bool] = [:],
        pushOnCommit: Bool = false,
        remoteLocationWarned: Bool = false,
        icon: String? = nil,
        iconColor: String? = nil
    ) {
        self.id = id
-        self.bookmark = bookmark
+        self.grants = grants
        self.displayName = displayName
        self.lastKnownPath = lastKnownPath
        self.lastOpened = lastOpened
@@ -185,12 +215,153 @@ public struct BoardRecord: Codable, Sendable, Equatable, Identifiable {
        self.cardCount = cardCount
        self.windowFrame = windowFrame
        self.cardWindowFrames = cardWindowFrames
-        self.isOpenNow = isOpenNow
+        self.openNow = openNow
        self.pushOnCommit = pushOnCommit
        self.remoteLocationWarned = remoteLocationWarned
        self.icon = icon
        self.iconColor = iconColor
    }
+
+    // MARK: The per-edition slots
+
+    /// This edition's grant, or `nil` when it holds none — the unavailable-until-reopened case.
+    ///
+    /// An **empty** `Data` answers `nil` too: `recordOpen` stores one when the system refused to mint
+    /// a bookmark at all, and a slot holding nothing is indistinguishable from no slot for every
+    /// purpose this type has.
+    public func grant(forEdition editionID: String) -> Data? {
+        guard let grant = grants[editionID], !grant.isEmpty else { return nil }
+        return grant
+    }
+
+    public mutating func setGrant(_ grant: Data, forEdition editionID: String) {
+        grants[editionID] = grant
+    }
+
+    /// Whether this board is open in `editionID` right now — the restoration set, as a live marker
+    /// rather than an at-quit write (02-architecture.md § Launch and window lifecycle, settled).
+    ///
+    /// Set when the board's window opens, cleared on *user-initiated* close; quit's teardown
+    /// deliberately leaves it standing, because the boards open at quit are by definition the ones
+    /// to restore. **Crash recovery falls out for free**: after a crash the flags describe what was
+    /// open at crash time, so the next launch restores exactly that — no separate recovery logic, no
+    /// once-at-quit stamp to race teardown or miss when the app dies.
+    ///
+    /// **Per edition** (12-editions.md ▸ Both editions installed): an edition restores only the
+    /// boards *it* had open, so a board Pro has open never reopens in base — and the other direction
+    /// of the same fact is the popover's awareness line.
+    public func isOpen(inEdition editionID: String) -> Bool {
+        openNow[editionID] == true
+    }
+
+    public mutating func setOpen(_ isOpen: Bool, inEdition editionID: String) {
+        openNow[editionID] = isOpen
+    }
+
+    /// The editions other than `editionID` that have this board flagged open, sorted so the answer is
+    /// stable rather than a dictionary's order.
+    ///
+    /// **Liveness is not checked here** — that is the caller's, because a flag is a *claim* and a
+    /// crashed edition leaves its claims standing by design. See `BoardEditionPresence` for the rule
+    /// that turns this list into a line the popover can honestly show.
+    public func otherEditionsOpen(besides editionID: String) -> [String] {
+        openNow.filter { $0.key != editionID && $0.value }.keys.sorted()
+    }
+
+    /// Whether any edition at all holds a grant for this board — what tells
+    /// unavailable-until-reopened (some other edition minted the only grant) apart from a genuine
+    /// orphan (nobody can reach it).
+    public var isGrantedByAnyEdition: Bool {
+        grants.contains { !$0.value.isEmpty }
+    }
+
+    // MARK: Codable
+
+    /// Hand-written for exactly one reason: the two pre-App-Group keys have to keep decoding while
+    /// never being written again (see `legacyBookmark`). Everything else is the synthesized
+    /// behaviour restated — required for the four founding keys, so a genuinely broken file still
+    /// quarantines, and defaulted for every key added since, which is § Evolving this struct's policy
+    /// spelled out rather than implied by an `Optional`.
+    private enum CodingKeys: String, CodingKey {
+        case id
+        case grants
+        case openNow
+        case displayName
+        case lastKnownPath
+        case lastOpened
+        case laneCount
+        case cardCount
+        case windowFrame
+        case cardWindowFrames
+        case icon
+        case iconColor
+        case pushOnCommit
+        case remoteLocationWarned
+        /// Pre-App-Group. Read, never written.
+        case bookmark
+        /// Pre-App-Group. Read, never written.
+        case isOpenNow
+    }
+
+    public init(from decoder: any Decoder) throws {
+        let container = try decoder.container(keyedBy: CodingKeys.self)
+        id = try container.decode(UUID.self, forKey: .id)
+        displayName = try container.decode(String.self, forKey: .displayName)
+        lastKnownPath = try container.decode(String.self, forKey: .lastKnownPath)
+        lastOpened = try container.decode(Date.self, forKey: .lastOpened)
+        grants = try container.decodeIfPresent([String: Data].self, forKey: .grants) ?? [:]
+        openNow = try container.decodeIfPresent([String: Bool].self, forKey: .openNow) ?? [:]
+        laneCount = try container.decodeIfPresent(Int.self, forKey: .laneCount)
+        cardCount = try container.decodeIfPresent(Int.self, forKey: .cardCount)
+        windowFrame = try container.decodeIfPresent(WindowFrame.self, forKey: .windowFrame)
+        cardWindowFrames = try container.decodeIfPresent([String: WindowFrame].self, forKey: .cardWindowFrames)
+        icon = try container.decodeIfPresent(String.self, forKey: .icon)
+        iconColor = try container.decodeIfPresent(String.self, forKey: .iconColor)
+        pushOnCommit = try container.decodeIfPresent(Bool.self, forKey: .pushOnCommit) ?? false
+        remoteLocationWarned = try container.decodeIfPresent(Bool.self, forKey: .remoteLocationWarned) ?? false
+        legacyBookmark = try container.decodeIfPresent(Data.self, forKey: .bookmark)
+        legacyOpenNow = try container.decodeIfPresent(Bool.self, forKey: .isOpenNow)
+    }
+
+    public func encode(to encoder: any Encoder) throws {
+        var container = encoder.container(keyedBy: CodingKeys.self)
+        try container.encode(id, forKey: .id)
+        try container.encode(grants, forKey: .grants)
+        try container.encode(openNow, forKey: .openNow)
+        try container.encode(displayName, forKey: .displayName)
+        try container.encode(lastKnownPath, forKey: .lastKnownPath)
+        try container.encode(lastOpened, forKey: .lastOpened)
+        try container.encodeIfPresent(laneCount, forKey: .laneCount)
+        try container.encodeIfPresent(cardCount, forKey: .cardCount)
+        try container.encodeIfPresent(windowFrame, forKey: .windowFrame)
+        try container.encodeIfPresent(cardWindowFrames, forKey: .cardWindowFrames)
+        try container.encodeIfPresent(icon, forKey: .icon)
+        try container.encodeIfPresent(iconColor, forKey: .iconColor)
+        try container.encode(pushOnCommit, forKey: .pushOnCommit)
+        try container.encode(remoteLocationWarned, forKey: .remoteLocationWarned)
+        // `bookmark` and `isOpenNow` are deliberately absent: this is the tolerate-and-upgrade half
+        // of backward compatibility. An unknown key is dropped on the same terms — the synthesized
+        // conformance dropped them too, so the file's forward tolerance is exactly what it was.
+    }
+
+    /// Folds the two pre-App-Group keys into `editionID`'s slots and forgets them.
+    ///
+    /// **Only when the modern slot is empty**, in both cases: a file carrying both shapes was written
+    /// by a build that already knew about grants, and the legacy key is then stale by definition.
+    ///
+    /// **In memory only, at load.** The upgraded shape reaches disk on the next ordinary save —
+    /// "tolerate-and-upgrade on first write" — so merely *reading* a registry never rewrites it, and
+    /// a launch that opens nothing leaves the file exactly as it found it.
+    mutating func adoptLegacyKeys(as editionID: String) {
+        if let legacyBookmark, !legacyBookmark.isEmpty, grants.isEmpty {
+            grants[editionID] = legacyBookmark
+        }
+        if legacyOpenNow == true, openNow.isEmpty {
+            openNow[editionID] = true
+        }
+        legacyBookmark = nil
+        legacyOpenNow = nil
+    }
 }

 /// A recents row: the record, plus whether its board can be reached right now.
@@ -206,27 +377,48 @@ public enum RecentBoard: Sendable, Equatable {
    /// The bookmark no longer resolves: deleted, or moved across a volume boundary a bookmark
    /// cannot follow. Orphaned — "its settings are conveniences and die with it".
    case unavailable(BoardRecord)
+    /// **Unavailable-until-reopened**: this edition holds no grant, but another edition does
+    /// (12-editions.md ▸ Distribution — "a record another edition minted resolves
+    /// unavailable-until-reopened, and the first click runs an open panel pre-anchored at the
+    /// recorded path: one click + Grant per board, once per edition").
+    ///
+    /// `recordedAt` is `lastKnownPath` as a URL — the panel's anchor, and the one place that field is
+    /// used for anything but display. It is **not** a claim that the board is there: nothing here
+    /// touches the filesystem, and a board that has since moved simply opens the panel at its parent.
+    case needsReopen(BoardRecord, recordedAt: URL)

    public var record: BoardRecord {
        switch self {
        case let .available(record, _): record
        case let .unavailable(record): record
+        case let .needsReopen(record, _): record
        }
    }

-    /// Where the board is now, or `nil` for an orphan.
+    /// Where the board is now, or `nil` when this edition cannot reach it — an orphan, or a record
+    /// awaiting this edition's grant. Both answer `nil` because both need something to happen before
+    /// a board can be opened; which something is `regrantAnchor`'s question.
    public var url: URL? {
        switch self {
        case let .available(_, url): url
-        case .unavailable: nil
+        case .unavailable, .needsReopen: nil
+        }
+    }
+
+    /// Where an open panel should start when this row is clicked, or `nil` for a row a panel cannot
+    /// help — an available board (nothing to grant) or a genuine orphan (nothing to grant *to*).
+    public var regrantAnchor: URL? {
+        switch self {
+        case let .needsReopen(_, url): url
+        case .available, .unavailable: nil
        }
    }
 }

 // MARK: - BoardRegistry

-/// The persistent side of per-board app state: one record per known board, in Application Support
-/// (02-architecture.md § Per-board app state).
+/// The persistent side of per-board app state: one record per known board, in the shared App Group
+/// container (02-architecture.md § Per-board app state; `AppGroup`).
 ///
 /// ### Three rules do most of the work
 ///
@@ -249,25 +441,31 @@ public enum RecentBoard: Sendable, Equatable {
 public final class BoardRegistry {

    /// The JSON file this registry is. Public because a diagnostic ("Reveal registry in Finder") and
-    /// every test want to name it, and because injecting it is how a test stays out of the real
-    /// Application Support directory.
+    /// every test want to name it, and because injecting it is how a test stays out of the real shared
+    /// App Group container (`AppGroup`) — which after the 2026-07-29 ruling is the sibling edition's
+    /// registry too, so a suite writing there would be editing two apps' state.
    public let storageURL: URL

+    /// **Which edition's slots this registry reads and writes** — the bundle id keying `grants` and
+    /// `openNow` on every shared record.
+    ///
+    /// Injected rather than read from `Bundle.main` at each use for the reason `storageURL` is
+    /// injected: it is how a test can be Pro looking at base's records (and back again) inside one
+    /// process, which is the only way the cross-edition rules are checkable at all.
+    public let editionID: String
+
    private var records: [BoardRecord]

    private static let logger = Logger(subsystem: "dev.rzen.indie.Kanban", category: "board-registry")

-    /// `~/Library/Application Support/<bundle id>/board-registry.json`, inside the sandbox
-    /// container. The bundle-id subfolder is Apple's convention and keeps the app's files together
-    /// as the app-wide neighbours arrive.
+    /// `<group container>/Library/Application Support/board-registry.json` — the **shared** home
+    /// (12-editions.md ▸ Distribution, ruled 2026-07-29), with no bundle-id subfolder, because the
+    /// absence of that subfolder is what makes one list serve every edition.
+    ///
+    /// `AppGroup.stateDirectory` falls back to the old per-edition path when the group is not
+    /// provisioned, so this is also the answer in a test host and in a locally signed build.
    public static var defaultStorageURL: URL {
-        let support = FileManager.default.urls(for: .applicationSupportDirectory, in: .userDomainMask).first
-            ?? URL(fileURLWithPath: NSHomeDirectory(), isDirectory: true)
-                .appendingPathComponent("Library/Application Support", isDirectory: true)
-        let bundleIdentifier = Bundle.main.bundleIdentifier ?? "dev.rzen.indie.Kanban"
-        return support
-            .appendingPathComponent(bundleIdentifier, isDirectory: true)
-            .appendingPathComponent("board-registry.json", isDirectory: false)
+        AppGroup.stateDirectory.appendingPathComponent("board-registry.json", isDirectory: false)
    }

    /// Loads the registry, tolerating everything a file on disk can be.
@@ -277,10 +475,85 @@ public final class BoardRegistry {
    /// because the file may be the only trace of a user's board list, and a support request can read
    /// it even when this app cannot; empty rather than fatal because a truncated convenience file
    /// must not stand between the user and their boards.
-    public init(storageURL: URL) {
+    ///
+    /// A file written before the per-edition slots existed is upgraded **in memory** on the way in
+    /// (`BoardRecord.adoptLegacyKeys(as:)`) — its one bookmark becomes this edition's grant — and
+    /// reaches disk in the new shape on the next ordinary save.
+    public init(storageURL: URL, editionID: String = AppGroup.editionID) {
        self.storageURL = storageURL
+        self.editionID = editionID
        self.records = []
-        self.records = loadFromDisk()
+        self.records = loadRecords()
+        self.fileStamp = Self.fileStamp(of: storageURL)
+    }
+
+    // MARK: - Two editions, one file
+
+    /// What the file looked like as of this registry's last read or write.
+    ///
+    /// The whole of the cross-edition freshness mechanism (see `syncFromDiskIfChanged`). `nil` means
+    /// "there is no file", which is the first-launch state and not a stale one.
+    private var fileStamp: FileStamp?
+
+    private struct FileStamp: Equatable {
+        let modified: Date
+        let size: Int
+    }
+
+    /// **`FileManager.attributesOfItem` and deliberately not `URL.resourceValues`.** A `URL` *caches*
+    /// resource values on the instance it was asked through, and this registry holds one `storageURL`
+    /// for its whole life — so the second question would be answered with the first question's answer,
+    /// and a stamp that never changes is a freshness check that never fires. (Measured, not assumed:
+    /// with `resourceValues` here, each edition kept its own pre-write view and the last save won
+    /// wholesale, which is exactly the bug this mechanism exists to prevent.)
+    private static func fileStamp(of url: URL) -> FileStamp? {
+        guard let attributes = try? FileManager.default.attributesOfItem(atPath: url.path),
+              let modified = attributes[.modificationDate] as? Date,
+              let size = attributes[.size] as? Int
+        else { return nil }
+        return FileStamp(modified: modified, size: size)
+    }
+
+    /// Re-reads the file when somebody else has written it — **the sibling edition**.
+    ///
+    /// ### Why this is needed at all
+    ///
+    /// The registry is one shared file now (12-editions.md ▸ Distribution) and "the same board open in
+    /// both apps at once is fine … a supported steady state, not a transition to hurry past" (▸ Both
+    /// editions installed). But this type holds its records in memory for the life of a launch and
+    /// `save()` writes the array *wholesale* — so without this, base running for an hour would, on its
+    /// next window-frame save, silently erase every record Pro wrote in that hour. That is not a narrow
+    /// race; it is the ordinary outcome of the steady state the design blesses.
+    ///
+    /// **Disk is the truth and this cache is only a cache**, which is what makes the fix this small:
+    /// there is no in-memory state to reconcile, because every mutation here saves immediately. So a
+    /// reload is a plain replacement, and the merge problem never arises.
+    ///
+    /// ### Why a stamp rather than an unconditional read
+    ///
+    /// One `stat` instead of a file read and a JSON parse, and — the part that matters — **exactly zero
+    /// behavioural change when one edition is running**: the stamp is recorded on every save, so our own
+    /// writes never look like somebody else's. Sub-second `contentModificationDate` plus the size makes
+    /// a missed change vanishingly unlikely, and the cost of missing one is the pre-existing behaviour.
+    ///
+    /// The honest residual, stated: the window between this check and the write that follows it is still
+    /// last-writer-wins. It is microseconds rather than hours, and what it can cost is one convenience
+    /// field — 02 § Per-board app state's "its settings are conveniences" already accepts exactly that.
+    private func syncFromDiskIfChanged() {
+        let current = Self.fileStamp(of: storageURL)
+        guard current != fileStamp else { return }
+        Self.logger.debug("the registry file changed underneath us — re-reading the sibling edition's writes")
+        fileStamp = current
+        records = loadRecords()
+    }
+
+    /// The load, plus the legacy-key adoption every load applies (see `init`).
+    private func loadRecords() -> [BoardRecord] {
+        loadFromDisk().map { record in
+            var record = record
+            record.adoptLegacyKeys(as: editionID)
+            return record
+        }
    }

    // MARK: - Opening and closing
@@ -335,6 +608,8 @@ public final class BoardRegistry {
        icon: String? = nil,
        iconColor: String? = nil
    ) -> UUID {
+        syncFromDiskIfChanged()
+
        let bookmark = Self.makeBookmark(for: rootURL)?.data ?? Data()
        if bookmark.isEmpty {
            // Both the security-scoped and the plain attempt failed — vanishingly unlikely for a
@@ -344,7 +619,11 @@ public final class BoardRegistry {
        }

        if let index = indexOfRecord(matching: rootURL) {
-            records[index].bookmark = bookmark
+            // **This edition's slot only.** A match found through the cross-edition fallback below is
+            // precisely the re-grant flow (12-editions.md: "one click + Grant per board, once per
+            // edition") — it mints *this* edition's grant onto the shared record and leaves the other
+            // edition's untouched, so the board stays reachable from both.
+            records[index].setGrant(bookmark, forEdition: editionID)
            if let displayName {
                records[index].displayName = displayName
                records[index].icon = icon
@@ -357,7 +636,7 @@ public final class BoardRegistry {
        }

        let record = BoardRecord(
-            bookmark: bookmark,
+            grants: [editionID: bookmark],
            displayName: displayName ?? Self.folderName(of: rootURL),
            lastKnownPath: rootURL.path,
            lastOpened: Self.stamp(),
@@ -410,7 +689,7 @@ public final class BoardRegistry {
    /// Marks this board as open — called when its window has actually opened, not when the open was
    /// merely attempted (02-architecture.md § Launch and window lifecycle).
    public func setOpenNow(id: UUID) {
-        update(id) { $0.isOpenNow = true }
+        update(id) { [editionID] in $0.setOpen(true, inEdition: editionID) }
    }

    /// Clears the marker — **user-initiated close only**.
@@ -421,7 +700,20 @@ public final class BoardRegistry {
    /// whole mechanism)". A crash calls nothing at all, which is why crash recovery needs no code of
    /// its own — the flags already describe what was open when the app died.
    public func clearOpenNow(id: UUID) {
-        update(id) { $0.isOpenNow = false }
+        update(id) { [editionID] in $0.setOpen(false, inEdition: editionID) }
+    }
+
+    /// The **other** editions with this board flagged open — the raw flags, what the board popover's
+    /// awareness line is derived from (12-editions.md ▸ Both editions installed: "the board popover
+    /// carries a contextual awareness line … read from the other edition's flag,
+    /// pid-liveness-checked so crash residue never lies").
+    ///
+    /// **Deliberately unfiltered.** Liveness is `BoardEditionPresence`'s half and lives there once: a
+    /// flag is a claim this file records faithfully, including the stale claim a crashed edition
+    /// leaves behind, and deciding which claims are still true needs `NSRunningApplication` — which
+    /// this `Foundation`-only file has no business reaching for.
+    public func otherEditionsFlaggedOpen(id: UUID) -> [String] {
+        record(id: id)?.otherEditionsOpen(besides: editionID) ?? []
    }

    /// The boards to reopen at launch: every record still flagged open, **oldest `lastOpened`
@@ -435,10 +727,15 @@ public final class BoardRegistry {
    /// (§ "A restored board that fails surfaces on welcome, row-level") instead of hanging on a
    /// mount.
    ///
+    /// **This edition's flags only** (12-editions.md ▸ Both editions installed): "an edition restores
+    /// only the boards *it* had open". A board Pro has open is Pro's to reopen, and base opening it
+    /// too at launch would be the app deciding for the user that two windows onto one board is what
+    /// they meant.
+    ///
    /// The preference gates only whether this is *consulted*; the flags are maintained regardless.
    public func restorables() -> [RecentBoard] {
        recents()
-            .filter { $0.record.isOpenNow == true }
+            .filter { $0.record.isOpen(inEdition: editionID) }
            // Ascending, with the same id tie-break `recents()` uses inverted, so two boards opened
            // in the same millisecond still come back in one stable order rather than whichever
            // `sorted(by:)` felt like.
@@ -493,6 +790,7 @@ public final class BoardRegistry {
    /// An unknown id is `update`'s own no-op (a board closed and forgotten mid-reload), for the
    /// same reason every other setter here tolerates one.
    public func syncDisplayState(id: UUID, title: String, icon: String?, iconColor: String?) {
+        syncFromDiskIfChanged()
        guard let index = indexOfRecord(id) else {
            Self.logger.debug("syncDisplayState: no record for this id — ignored")
            return
@@ -535,18 +833,27 @@ public final class BoardRegistry {
    /// refreshed: it is the display fallback for a record that *cannot* be resolved, so the resolved
    /// URL, not the record, is what an available row shows.
    ///
+    /// **Three states, not two** (12-editions.md ▸ Distribution): a record this edition holds no grant
+    /// for, but some other edition does, is `needsReopen` — unavailable-until-reopened, with the
+    /// recorded path as the open panel's anchor. A record nobody can reach is the orphan it always
+    /// was. Only this edition's slot is ever resolved or refreshed; another edition's bookmark is not
+    /// this app's to resolve and would fail if it tried.
+    ///
    /// The sort is total — `lastOpened` descending, then id — because `sorted(by:)` is not stable
    /// and two rows that tie should still come back in the same order every call.
    public func recents() -> [RecentBoard] {
+        syncFromDiskIfChanged()
+
        var resolvedURLs: [UUID: URL] = [:]
        var refreshedAny = false

        for index in records.indices {
-            guard let resolution = Self.resolve(records[index].bookmark) else { continue }
+            guard let grant = records[index].grant(forEdition: editionID),
+                  let resolution = Self.resolve(grant) else { continue }
            resolvedURLs[records[index].id] = resolution.url
            guard resolution.isStale else { continue }
            if let refreshed = Self.withScopedAccess(to: resolution.url, { Self.makeBookmark(for: $0) }) {
-                records[index].bookmark = refreshed.data
+                records[index].setGrant(refreshed.data, forEdition: editionID)
                refreshedAny = true
            }
        }
@@ -563,20 +870,30 @@ public final class BoardRegistry {
            .map { record in
                if let url = resolvedURLs[record.id] {
                    .available(record, at: url)
+                } else if record.grant(forEdition: editionID) == nil, record.isGrantedByAnyEdition {
+                    // No grant of ours, but somebody's — the cross-edition row. Note the order: a
+                    // grant of ours that *failed to resolve* falls through to `unavailable` below,
+                    // which is right. That is Graceful orphaning's case (the board is gone), not the
+                    // re-grant case (the board is there and we were never given it).
+                    .needsReopen(record, recordedAt: URL(fileURLWithPath: record.lastKnownPath, isDirectory: true))
                } else {
                    .unavailable(record)
                }
            }
    }

+    /// One record, fresh — the sibling edition's writes included, which is what lets the popover's
+    /// awareness line see a flag Pro set after this app launched.
    public func record(id: UUID) -> BoardRecord? {
-        records.first { $0.id == id }
+        syncFromDiskIfChanged()
+        return records.first { $0.id == id }
    }

    /// Drops a record — the Forget action on an orphaned recents row, and the only way a record
    /// leaves. Nothing else prunes: a board that is merely unavailable today may be a remounted
    /// volume tomorrow, so forgetting is always the user's call.
    public func forget(id: UUID) {
+        syncFromDiskIfChanged()
        guard let index = indexOfRecord(id) else { return }
        records.remove(at: index)
        save()
@@ -592,6 +909,7 @@ public final class BoardRegistry {
    /// One save rather than one per record: the file is rewritten wholesale anyway, and forgetting
    /// twenty boards should not be twenty writes.
    public func forgetAll() {
+        syncFromDiskIfChanged()
        guard !records.isEmpty else { return }
        records.removeAll()
        save()
@@ -599,11 +917,22 @@ public final class BoardRegistry {

    // MARK: - Matching

-    /// The index of the record whose bookmark resolves to the same file as `url`, if any.
+    /// The index of the record whose grant resolves to the same file as `url`, if any — falling back
+    /// to the recorded path for records this edition has no grant for at all.
+    ///
+    /// **File identity is still the rule.** The fallback is not a second identity mechanism; it is the
+    /// only locator available for a record only *another* edition can resolve, and it is the same
+    /// locator the design already nominates for that case — "an open panel pre-anchored at the
+    /// recorded path" (12-editions.md). It is consulted only after identity has failed, and only
+    /// against records holding no grant of ours, so a board this edition knows can never be matched by
+    /// its path. Without it, granting a board in the second edition would fork the shared record into
+    /// two and undo the whole point of sharing it.
    private func indexOfRecord(matching url: URL) -> Int? {
        guard let target = FileIdentity(of: url) else { return nil }
-        return records.firstIndex { record in
-            guard let resolution = Self.resolve(record.bookmark) else { return false }
+
+        let byIdentity = records.firstIndex { record in
+            guard let grant = record.grant(forEdition: editionID),
+                  let resolution = Self.resolve(grant) else { return false }
            // Scope is started around the identity read and stopped immediately. Resolving a
            // security-scoped bookmark grants nothing by itself, and in the sandbox an unscoped
            // `resourceValues` call on some *other* board's folder is exactly the read that gets
@@ -612,6 +941,21 @@ public final class BoardRegistry {
            // unaffected.
            return Self.withScopedAccess(to: resolution.url) { FileIdentity(of: $0) == target }
        }
+        if let byIdentity { return byIdentity }
+
+        let key = Self.pathKey(url.path)
+        return records.firstIndex { record in
+            record.grant(forEdition: editionID) == nil
+                && record.isGrantedByAnyEdition
+                && Self.pathKey(record.lastKnownPath) == key
+        }
+    }
+
+    /// How two paths are compared for "the same board" in the fallback above — standardized, never
+    /// resolved through symlinks, which is `WelcomeRow.pathKey`'s rule restated rather than imported
+    /// (this file is `Foundation`-only and must not reach into the app layer).
+    private static func pathKey(_ path: String) -> String {
+        URL(fileURLWithPath: path).standardizedFileURL.path
    }

    private func indexOfRecord(_ id: UUID) -> Int? {
@@ -621,6 +965,7 @@ public final class BoardRegistry {
    /// Mutates a record and saves. An unknown id is a no-op: a window that outlived its record —
    /// the user pressed Forget while the board was open — must not crash on its way out.
    private func update(_ id: UUID, _ mutate: (inout BoardRecord) -> Void) {
+        syncFromDiskIfChanged()
        guard let index = indexOfRecord(id) else {
            Self.logger.debug("update: no record for this id — ignored")
            return
@@ -761,6 +1106,10 @@ public final class BoardRegistry {
                withIntermediateDirectories: true
            )
            try encoder.encode(ordered).write(to: storageURL, options: .atomic)
+            // Recorded *after* the write, so our own bytes never read as the sibling's on the next
+            // `syncFromDiskIfChanged` — which is what keeps a single-edition launch behaving exactly as
+            // it did before that mechanism existed.
+            fileStamp = Self.fileStamp(of: storageURL)
        } catch {
            Self.logger.error("could not save the board registry: \(error.localizedDescription, privacy: .public)")
        }
@@ -46,8 +46,10 @@ public final class StyleRecents {
    private static let logger = Logger(subsystem: "dev.rzen.indie.Kanban", category: "style-recents")

    /// - Parameter defaults: the domain to persist in. Injected for the reason `BoardRegistry` takes
-    ///   its storage URL: a test must be able to hold its own without touching the user's.
-    public init(defaults: UserDefaults = .standard) {
+    ///   its storage URL: a test must be able to hold its own without touching the user's. The app's
+    ///   own is the **group's shared suite** (02-architecture.md § Per-board app state, ruled
+    ///   2026-07-29), so the row an upgrader built up in base is the row Pro offers.
+    public init(defaults: UserDefaults = AppGroup.defaults) {
        self.defaults = defaults
        // Anything but an array of strings is treated as an empty list rather than as an error: this
        // is a convenience, and a hand-edited or truncated preference must never be the reason a
@@ -68,6 +68,15 @@ struct BoardInfoWidget: View {
    let store: BoardStore
    let recents: StyleRecents

+    /// The cross-edition awareness line's *fact*, asked afresh each time the popover is built — see
+    /// `BoardEditionPresence` for why it is a closure rather than a value: both halves of it (the
+    /// registry's flags and whether the other app is alive) can change while a board window sits
+    /// there, and neither is a thing to observe.
+    ///
+    /// Defaulted to "no line" so the two surfaces that build this widget without a registry — the
+    /// titlebar tests — keep saying nothing rather than needing one.
+    var otherEditionNote: () -> String? = { nil }
+
    @Bindable var presentation: BoardInfoPresentation

    var body: some View {
@@ -87,7 +96,7 @@ struct BoardInfoWidget: View {
        .help("Board Info")
        .accessibilityLabel("Board Info")
        .popover(isPresented: $presentation.isPresented, arrowEdge: .bottom) {
-            BoardInfoView(store: store, recents: recents)
+            BoardInfoView(store: store, recents: recents, otherEditionNote: otherEditionNote())
        }
    }
 }
@@ -103,10 +112,16 @@ struct BoardInfoWidget: View {
 func boardInfoTitlebarAccessory(
    store: BoardStore,
    recents: StyleRecents,
-    presentation: BoardInfoPresentation
+    presentation: BoardInfoPresentation,
+    otherEditionNote: @escaping () -> String? = { nil }
 ) -> NSTitlebarAccessoryViewController {
    let hosting = NSHostingView(
-        rootView: BoardInfoWidget(store: store, recents: recents, presentation: presentation)
+        rootView: BoardInfoWidget(
+            store: store,
+            recents: recents,
+            otherEditionNote: otherEditionNote,
+            presentation: presentation
+        )
    )
    // The titlebar lays its accessories out by fitting size, and a hosting view that measured itself
    // as zero would be an invisible, unclickable widget.
@@ -137,6 +152,10 @@ struct BoardInfoView: View {
    /// See `BoardGitNote.hasGitDirectory(at:)` for why a live-updating fact isn't needed here.
    private let hasGitDirectory: Bool

+    /// The cross-edition awareness line, or `nil` for no line — resolved once when the view is built,
+    /// on `hasGitDirectory`'s terms and for its reason (`BoardEditionPresence`).
+    private let otherEditionNote: String?
+
    /// The style editor brings its own padding, so the sections around it carry the same number by
    /// hand instead of an outer padding that would double up on it — **the editor's own figure**
    /// (`StyleEditorLayout.sectionSpacing`), which is font-derived, so the popover's chrome scales
@@ -145,10 +164,11 @@ struct BoardInfoView: View {
        StyleEditorLayout.sectionSpacing(bodyPointSize: CardWindowMetrics.bodyPointSize)
    }

-    init(store: BoardStore, recents: StyleRecents) {
+    init(store: BoardStore, recents: StyleRecents, otherEditionNote: String? = nil) {
        self.store = store
        self.recents = recents
        self.hasGitDirectory = BoardGitNote.hasGitDirectory(at: store.rootURL)
+        self.otherEditionNote = otherEditionNote
    }

    var body: some View {
@@ -176,9 +196,20 @@ struct BoardInfoView: View {
            // nothing here at all — no header, no divider, no placeholder — and the popover ends at
            // Styling, complete in itself. Only a board that actually carries an inert `.git` earns
            // this closing note.
-            if hasGitDirectory {
+            //
+            // The awareness line is its neighbour on the same terms, and the two stack in one section
+            // when both are true — a `.git`-bearing board open in Pro is exactly the household where
+            // both sentences apply, and each answers a different question.
+            if hasGitDirectory || otherEditionNote != nil {
                Divider()
+                VStack(alignment: .leading, spacing: 4) {
+                    if hasGitDirectory {
                        BoardGitNote()
+                    }
+                    if let otherEditionNote {
+                        BoardEditionPresenceNote(text: otherEditionNote)
+                    }
+                }
                .padding(inset)
            }
        }
@@ -310,3 +341,70 @@ struct BoardGitNote: View {
        FileManager.default.fileExists(atPath: boardRoot.appendingPathComponent(".git").path)
    }
 }
+
+// MARK: - The other edition
+
+/// **The cross-edition awareness line** — "Also open in Lanework Pro" (12-editions.md ▸ Both editions
+/// installed, ruled 2026-07-29).
+///
+/// > Two conveniences ride the shared registry: open-now flags are per-edition …, and the board
+/// > popover carries a contextual awareness line ("Also open in Lanework Pro") read from the other
+/// > edition's flag, **pid-liveness-checked so crash residue never lies** — a line, never a gate.
+///
+/// It is `BoardGitNote`'s posture applied to a different fact: contextual, absent when untrue, and
+/// never a control. Nothing about it gates anything — the same board open in both apps is the designed
+/// foreign-writer story (12), so this line exists to *explain* what the user is looking at, not to
+/// warn them off it.
+///
+/// ### Why liveness matters, and why it is a parameter
+///
+/// The flag is a live open marker that a crash deliberately leaves standing (02-architecture.md
+/// § Launch and window lifecycle — that residue is what makes crash recovery free). So a flag alone
+/// would claim "also open in Lanework Pro" about an app that died last Tuesday. `NSRunningApplication`
+/// settles it, and the check is injected so `note(otherEditions:isRunning:)` is a pure function the
+/// tests pin directly — the same seam `BoardGitNote.hasGitDirectory(at:)` is.
+enum BoardEditionPresence {
+
+    /// Whether an edition is running right now, by bundle id — the pid-liveness half.
+    ///
+    /// `NSRunningApplication.runningApplications(withBundleIdentifier:)` rather than a stored pid: the
+    /// registry records *which* edition had the board open, never a process id, and it should not
+    /// start — a pid is a fact with a shelf life of milliseconds, and the bundle id is the question
+    /// actually being asked.
+    @MainActor
+    static func isRunning(_ bundleID: String) -> Bool {
+        !NSRunningApplication.runningApplications(withBundleIdentifier: bundleID).isEmpty
+    }
+
+    /// The line, or `nil` for no line at all.
+    ///
+    /// Three ways to get `nil`, and each is the honest answer: no other edition has the board flagged;
+    /// the flagged edition is not running (crash residue); or the flagged bundle id is one this build
+    /// cannot name (`AppGroup.editionDisplayName`) — a future edition, where inventing a name would be
+    /// worse than saying nothing.
+    ///
+    /// **One line even when several editions qualify**, taking the first by the sorted order the
+    /// registry hands over: the popover has room for a sentence, not a roster, and with Teams
+    /// deferred there is no case today where two others are open at once.
+    static func note(otherEditions: [String], isRunning: (String) -> Bool) -> String? {
+        for bundleID in otherEditions {
+            guard isRunning(bundleID), let name = AppGroup.editionDisplayName(bundleID) else { continue }
+            return "Also open in \(name)"
+        }
+        return nil
+    }
+}
+
+/// The awareness line as a view, beside `BoardGitNote` and styled identically — the two contextual
+/// notes are one register, so a popover carrying both reads as one surface.
+struct BoardEditionPresenceNote: View {
+
+    let text: String
+
+    var body: some View {
+        Text(text)
+            .font(.caption)
+            .foregroundStyle(.secondary)
+            .fixedSize(horizontal: false, vertical: true)
+    }
+}
@@ -10,6 +10,15 @@
 	<true/>
 	<key>com.apple.security.files.bookmarks.app-scope</key>
 	<true/>
+	<!-- The family App Group, **verbatim** the same id base declares (12-editions.md ▸
+	     Distribution, ruled 2026-07-29): one container, one registry, one clipboard staging store,
+	     one defaults suite. The whole upgrade story is this key matching base's — an edition
+	     declaring a group of its own would share nothing while looking as though it did. Teams
+	     joins by declaring this same string. -->
+	<key>com.apple.security.application-groups</key>
+	<array>
+		<string>group.dev.rzen.indie.Kanban</string>
+	</array>
 	<!-- Pro only (12-editions.md ▸ Targets): remotes. Base ships without this key at all, which
 	     is what makes "base cannot talk to a network" a checkable property of the signed binary
 	     rather than a promise about the source (scripts/verify-editions.sh). -->
@@ -0,0 +1,493 @@
+import Foundation
+import Testing
+@testable import Kanban
+
+/// **App-side state in the shared App Group container** (12-editions.md ▸ Distribution and ▸ Both
+/// editions installed, ruled 2026-07-29; 02-architecture.md § Per-board app state).
+///
+/// One container, one registry, one clipboard staging store, one defaults suite — and exactly two
+/// fields that cannot be shared, both keyed by bundle id: the security-scoped **grant slot** (a
+/// bookmark never crosses a sandbox, group or not) and the **open-now flag** (an edition restores only
+/// the boards it had open). Everything here is about those two seams and what they buy.
+///
+/// **Nothing in this file touches the real group container.** Every registry gets a temp storage file
+/// and every edition is a *string*, injected — which is the only way "base's record, read by Pro" is
+/// expressible inside one process at all.
+
+// MARK: - Fixtures
+
+/// A temp registry file, `BoardRegistryTests`' own shape — restated rather than shared because that
+/// file's copy is `private` to it and a test fixture is not worth a seam.
+@MainActor
+private struct GroupStorage {
+    let folder: URL
+
+    var url: URL { folder.appendingPathComponent("board-registry.json", isDirectory: false) }
+
+    init() throws {
+        folder = FileManager.default.temporaryDirectory
+            .appendingPathComponent("AppGroupStateTests-\(UUID().uuidString)", isDirectory: true)
+        try FileManager.default.createDirectory(at: folder, withIntermediateDirectories: true)
+    }
+
+    func tearDown() {
+        try? FileManager.default.removeItem(at: folder)
+    }
+}
+
+@MainActor
+private func makeGroupBoard() throws -> WriterFixture {
+    let fixture = try WriterFixture()
+    try fixture.item("", Item.board)
+    try fixture.item(Ident.lane1, Item.rich(order: "1024", title: "Todo"))
+    return fixture
+}
+
+private let base = AppGroup.baseEditionID
+private let pro = AppGroup.proEditionID
+
+// MARK: - The container
+
+@MainActor
+@Suite("App Group container")
+struct AppGroupContainerTests {
+
+    @Test("Every app-side store resolves under one state directory, provisioned or not")
+    func stateDirectoryIsOneHomeAndAlwaysUsable() async throws {
+        // Diagnostic, not an assertion: whether this test host has the capability is a fact about
+        // provisioning, and a suite that *required* it could not run on a machine where the group is
+        // not yet registered on the team. Printed for the same reason `BoardRegistryTests` prints its
+        // bookmark flavor — the answer matters and cannot be asserted.
+        let container = AppGroup.containerURL
+        print("AppGroupStateTests: group container in this host = \(container?.path ?? "nil (unprovisioned — per-edition fallback)")")
+
+        let production = AppGroup.productionStateDirectory
+        if let container {
+            #expect(production.path.hasPrefix(container.path), "the shared home is inside the group container")
+            // No bundle-id **subfolder** — that subfolder is what kept the editions apart. Compared by
+            // path component, not by substring: the group id itself contains base's bundle id, which is
+            // the family name showing through and not a per-edition directory.
+            #expect(
+                !production.pathComponents.contains(AppGroup.editionID),
+                "the shared home must not be nested under a per-edition folder"
+            )
+        } else {
+            #expect(
+                production == AppGroup.perEditionSupportDirectory,
+                "the fallback is the pre-2.0 per-edition home, unshared but working"
+            )
+        }
+
+        // The registry and the clipboard's staging store share one home, which is the whole point:
+        // "the clipboard staging store homes in the group container **beside the registry**".
+        let state = AppGroup.stateDirectory
+        #expect(BoardRegistry.defaultStorageURL.deletingLastPathComponent() == state)
+        #expect(ClipboardStore.defaultStagingRoot.deletingLastPathComponent() == state)
+        // And the template store, re-homed here on the same day (09-templates.md ▸ Storage): "templates
+        // cross editions".
+        #expect(TemplateEngine.userStore.deletingLastPathComponent() == state)
+
+        // And it is a directory the app can actually create, which is the only property that has to
+        // hold on both sides of the provisioning question.
+        try FileManager.default.createDirectory(at: state, withIntermediateDirectories: true)
+        #expect(FileManager.default.fileExists(atPath: state.path))
+    }
+
+    @Test("A unit-test host never resolves to the real shared container")
+    func aTestHostIsRedirected() {
+        // This suite is running, so this *is* a test host — and the point of the check is that the two
+        // defaults every launch reaches for (the registry file, the staging root) cannot land in a
+        // container shared with the sibling edition and with the developer's own running copy. There is
+        // no injection point in `KanbanApp.init()` to fix that from the outside.
+        #expect(AppGroup.isUnitTestHost)
+        #expect(AppGroup.stateDirectory == AppGroup.unitTestStateDirectory)
+        #expect(AppGroup.stateDirectory != AppGroup.productionStateDirectory)
+        #expect(AppGroup.defaults != UserDefaults(suiteName: AppGroup.identifier))
+    }
+
+    @Test("The group id is the family's, and each edition names itself")
+    func editionIdentityIsReadFromTheBundle() {
+        #expect(AppGroup.identifier == "group.dev.rzen.indie.Kanban")
+        #expect(AppGroup.perEditionSupportDirectory.lastPathComponent == AppGroup.editionID)
+        #expect(AppGroup.editionDisplayName(base) == "Lanework")
+        #expect(AppGroup.editionDisplayName(pro) == "Lanework Pro")
+        // A bundle id this build cannot name gets no name invented for it — the awareness line's whole
+        // posture is that it never says anything it does not know.
+        #expect(AppGroup.editionDisplayName("dev.rzen.indie.KanbanTeams") == nil)
+    }
+}
+
+// MARK: - Grant slots
+
+@MainActor
+@Suite("Per-edition grant slots")
+struct GrantSlotTests {
+
+    @Test("A grant is minted into this edition's slot and round-trips through the file")
+    func grantSlotsRoundTrip() async throws {
+        let storage = try GroupStorage()
+        defer { storage.tearDown() }
+        let fixture = try makeGroupBoard()
+        defer { fixture.tearDown() }
+
+        let asBase = BoardRegistry(storageURL: storage.url, editionID: base)
+        let id = asBase.recordOpen(of: fixture.root, displayName: "Work")
+
+        let reloaded = try #require(BoardRegistry(storageURL: storage.url, editionID: base).record(id: id))
+        #expect(reloaded.grant(forEdition: base) != nil)
+        #expect(reloaded.grant(forEdition: pro) == nil, "an edition mints its own slot and nobody else's")
+    }
+
+    @Test("A record the other edition minted resolves unavailable-until-reopened, anchored at its path")
+    func otherEditionsGrantNeedsReopening() async throws {
+        let storage = try GroupStorage()
+        defer { storage.tearDown() }
+        let fixture = try makeGroupBoard()
+        defer { fixture.tearDown() }
+
+        BoardRegistry(storageURL: storage.url, editionID: base)
+            .recordOpen(of: fixture.root, displayName: "Work")
+
+        // Pro, over the very same shared file. The board is *there* — nothing was deleted — but the
+        // only bookmark on the record was minted in another sandbox, so this edition cannot resolve it.
+        let asPro = BoardRegistry(storageURL: storage.url, editionID: pro)
+        let rows = asPro.recents()
+        #expect(rows.count == 1, "the record is shared, not duplicated")
+
+        guard case let .needsReopen(record, anchor) = rows[0] else {
+            Issue.record("expected needsReopen, got \(rows[0])")
+            return
+        }
+        #expect(record.displayName == "Work", "every other field is common — the list transfers, only access re-grants")
+        #expect(anchor.standardizedFileURL.path == URL(fileURLWithPath: fixture.root.path).standardizedFileURL.path)
+        #expect(rows[0].url == nil, "there is nothing to open until the grant exists")
+        #expect(rows[0].regrantAnchor != nil)
+    }
+
+    @Test("A genuine orphan is not a re-grant candidate")
+    func aRecordNobodyCanReachStaysUnavailable() async throws {
+        let storage = try GroupStorage()
+        defer { storage.tearDown() }
+
+        // No grants at all — the born-orphaned record (`recordOpen`'s degenerate case). The two states
+        // are told apart by whether *somebody* holds a grant, so this one must stay `unavailable`: an
+        // open panel cannot help a board nothing knows the whereabouts of.
+        let id = UUID()
+        let json = """
+        [
+          {
+            "displayName" : "Ghost",
+            "grants" : {},
+            "id" : "\(id.uuidString)",
+            "lastKnownPath" : "/Volumes/Gone/Ghost.kanban",
+            "lastOpened" : "2026-01-01T09:00:00.000Z",
+            "openNow" : {},
+            "pushOnCommit" : false,
+            "remoteLocationWarned" : false
+          }
+        ]
+        """
+        try Data(json.utf8).write(to: storage.url)
+
+        let rows = BoardRegistry(storageURL: storage.url, editionID: pro).recents()
+        #expect(rows.count == 1)
+        guard case .unavailable = rows[0] else {
+            Issue.record("expected unavailable, got \(rows[0])")
+            return
+        }
+    }
+
+    @Test("Re-granting mints this edition's slot onto the shared record and leaves the other's alone")
+    func regrantingDoesNotForkTheRecord() async throws {
+        let storage = try GroupStorage()
+        defer { storage.tearDown() }
+        let fixture = try makeGroupBoard()
+        defer { fixture.tearDown() }
+
+        let asBase = BoardRegistry(storageURL: storage.url, editionID: base)
+        let id = asBase.recordOpen(of: fixture.root, displayName: "Work")
+        asBase.updateWindowFrame(id: id, frame: WindowFrame(x: 10, y: 20, width: 300, height: 400))
+        let baseGrant = try #require(asBase.record(id: id)?.grant(forEdition: base))
+
+        // The re-grant: the panel handed Pro the same folder, and the open goes through the ordinary
+        // `recordOpen` door. Nothing about it is a special API — that is the design.
+        let asPro = BoardRegistry(storageURL: storage.url, editionID: pro)
+        let proID = asPro.recordOpen(of: fixture.root)
+        #expect(proID == id, "the shared record is matched, never forked")
+
+        let shared = try #require(BoardRegistry(storageURL: storage.url, editionID: base).record(id: id))
+        #expect(shared.grant(forEdition: pro) != nil, "Pro now holds its own grant")
+        #expect(shared.grant(forEdition: base) == baseGrant, "base's grant is untouched — it is still that app's key")
+        #expect(shared.windowFrame?.width == 300, "and every common field survived the second edition's open")
+        #expect(BoardRegistry(storageURL: storage.url, editionID: pro).recents().count == 1)
+
+        // Both editions can now reach it.
+        guard case .available = BoardRegistry(storageURL: storage.url, editionID: pro).recents()[0] else {
+            Issue.record("expected Pro to see the board as available after re-granting")
+            return
+        }
+    }
+
+    @Test("A registry file written before the grant slots existed adopts its one bookmark as this edition's")
+    func legacySingleGrantRecordsAreReadable() async throws {
+        let storage = try GroupStorage()
+        defer { storage.tearDown() }
+
+        // Byte-for-byte the pre-App-Group shape: one `bookmark`, one `isOpenNow`, no keyed slots at
+        // all. Only base existed then, so adopting the bookmark as the *running* edition's slot is the
+        // coherent reading — and the reachable case is the unprovisioned fallback, where
+        // `AppGroup.stateDirectory` still points at the old per-edition home.
+        let id = UUID()
+        let garbage = Data("not a bookmark".utf8).base64EncodedString()
+        let json = """
+        [
+          {
+            "bookmark" : "\(garbage)",
+            "cardCount" : 9,
+            "displayName" : "Archive",
+            "id" : "\(id.uuidString)",
+            "isOpenNow" : true,
+            "laneCount" : 4,
+            "lastKnownPath" : "/Volumes/Archive/Boards/Archive",
+            "lastOpened" : "2026-01-01T09:00:00.000Z",
+            "pushOnCommit" : true,
+            "remoteLocationWarned" : true
+          }
+        ]
+        """
+        try Data(json.utf8).write(to: storage.url)
+
+        let registry = BoardRegistry(storageURL: storage.url, editionID: base)
+        let record = try #require(registry.record(id: id))
+        #expect(record.grant(forEdition: base) != nil, "the one bookmark became this edition's grant")
+        #expect(record.isOpen(inEdition: base), "and the one flag became this edition's flag")
+        #expect(record.laneCount == 4, "every other field survived — nothing was quarantined")
+
+        // Its bookmark is unresolvable garbage, so it classifies as the orphan it is — never as a
+        // re-grant candidate, which would be this edition offering to grant a board it already holds
+        // the (dead) key to.
+        guard case .unavailable = registry.recents()[0] else {
+            Issue.record("expected unavailable, got \(registry.recents()[0])")
+            return
+        }
+
+        // Tolerate-and-upgrade **on first write**: reading changed nothing on disk, and the next
+        // ordinary save emits the keyed shape and drops the legacy keys for good.
+        #expect(try String(data: Data(contentsOf: storage.url), encoding: .utf8)?.contains("\"bookmark\"") == true)
+        registry.setRemoteLocationWarned(id: id)
+        let upgraded = try #require(String(data: Data(contentsOf: storage.url), encoding: .utf8))
+        #expect(!upgraded.contains("\"bookmark\""))
+        #expect(!upgraded.contains("\"isOpenNow\""))
+        #expect(upgraded.contains("\"grants\""))
+        #expect(BoardRegistry(storageURL: storage.url, editionID: base).record(id: id)?.grant(forEdition: base) != nil)
+    }
+}
+
+// MARK: - Open-now flags
+
+@MainActor
+@Suite("Per-edition open-now flags")
+struct OpenNowPerEditionTests {
+
+    @Test("An edition restores only the boards it had open")
+    func restorationIsFilteredByEdition() async throws {
+        let storage = try GroupStorage()
+        defer { storage.tearDown() }
+        let mine = try makeGroupBoard()
+        defer { mine.tearDown() }
+        let theirs = try makeGroupBoard()
+        defer { theirs.tearDown() }
+
+        let asBase = BoardRegistry(storageURL: storage.url, editionID: base)
+        let mineID = asBase.recordOpen(of: mine.root, displayName: "Mine")
+        let theirsID = asBase.recordOpen(of: theirs.root, displayName: "Theirs")
+        asBase.setOpenNow(id: mineID)
+
+        // Pro flags the other board — same shared records, its own slot.
+        let asPro = BoardRegistry(storageURL: storage.url, editionID: pro)
+        asPro.recordOpen(of: theirs.root)
+        asPro.setOpenNow(id: theirsID)
+
+        let baseRestores = BoardRegistry(storageURL: storage.url, editionID: base).restorables()
+        let proRestores = BoardRegistry(storageURL: storage.url, editionID: pro).restorables()
+        #expect(baseRestores.map(\.record.id) == [mineID])
+        #expect(proRestores.map(\.record.id) == [theirsID])
+
+        // And a user close in one edition leaves the other's flag standing.
+        BoardRegistry(storageURL: storage.url, editionID: base).clearOpenNow(id: mineID)
+        let after = try #require(BoardRegistry(storageURL: storage.url, editionID: pro).record(id: theirsID))
+        #expect(after.isOpen(inEdition: pro))
+        #expect(!after.isOpen(inEdition: base))
+    }
+
+    @Test("The other edition's flags are reported raw, never this edition's own")
+    func flaggedEditionsExcludeSelf() async throws {
+        let storage = try GroupStorage()
+        defer { storage.tearDown() }
+        let fixture = try makeGroupBoard()
+        defer { fixture.tearDown() }
+
+        let asBase = BoardRegistry(storageURL: storage.url, editionID: base)
+        let id = asBase.recordOpen(of: fixture.root, displayName: "Shared")
+        asBase.setOpenNow(id: id)
+
+        let asPro = BoardRegistry(storageURL: storage.url, editionID: pro)
+        asPro.setOpenNow(id: id)
+
+        #expect(asPro.otherEditionsFlaggedOpen(id: id) == [base])
+        #expect(BoardRegistry(storageURL: storage.url, editionID: base).otherEditionsFlaggedOpen(id: id) == [pro])
+        #expect(asPro.otherEditionsFlaggedOpen(id: UUID()).isEmpty, "an unknown id says nothing")
+    }
+}
+
+// MARK: - Two editions, one file
+
+@MainActor
+@Suite("One registry file, two live editions")
+struct SharedRegistryFileTests {
+
+    @Test("Neither edition's write erases the other's")
+    func writesFromBothEditionsSurvive() async throws {
+        let storage = try GroupStorage()
+        defer { storage.tearDown() }
+        let mine = try makeGroupBoard()
+        defer { mine.tearDown() }
+        let theirs = try makeGroupBoard()
+        defer { theirs.tearDown() }
+
+        // Both **live at once**, which is the steady state 12-editions.md blesses ("a supported steady
+        // state, not a transition to hurry past") — and the case a whole-file writer over a cached array
+        // gets wrong by default: base's next window-frame save would rewrite the file from an array that
+        // never heard of Pro's board.
+        let asBase = BoardRegistry(storageURL: storage.url, editionID: base)
+        let asPro = BoardRegistry(storageURL: storage.url, editionID: pro)
+
+        let mineID = asBase.recordOpen(of: mine.root, displayName: "Base's")
+        let theirsID = asPro.recordOpen(of: theirs.root, displayName: "Pro's")
+
+        // An ordinary convenience write from the edition that has not looked at the file since.
+        asBase.updateWindowFrame(id: mineID, frame: WindowFrame(x: 1, y: 2, width: 3, height: 4))
+
+        let onDisk = BoardRegistry(storageURL: storage.url, editionID: base)
+        #expect(Set(onDisk.recents().map(\.record.id)) == [mineID, theirsID], "both records are in the file")
+        #expect(onDisk.record(id: mineID)?.windowFrame?.width == 3)
+        #expect(onDisk.record(id: theirsID)?.grant(forEdition: pro) != nil, "and Pro's grant was not rewritten away")
+    }
+
+    @Test("A flag the other edition sets is visible without relaunching")
+    func theOtherEditionsFlagIsPickedUpLive() async throws {
+        let storage = try GroupStorage()
+        defer { storage.tearDown() }
+        let fixture = try makeGroupBoard()
+        defer { fixture.tearDown() }
+
+        let asBase = BoardRegistry(storageURL: storage.url, editionID: base)
+        let id = asBase.recordOpen(of: fixture.root, displayName: "Shared")
+
+        // Pro opens the same board afterwards. Base is still running and has not re-read anything — and
+        // the popover's awareness line is worthless if it can only see flags that predate this launch.
+        let asPro = BoardRegistry(storageURL: storage.url, editionID: pro)
+        asPro.recordOpen(of: fixture.root)
+        asPro.setOpenNow(id: id)
+
+        #expect(asBase.otherEditionsFlaggedOpen(id: id) == [pro])
+        #expect(
+            BoardEditionPresence.note(
+                otherEditions: asBase.otherEditionsFlaggedOpen(id: id),
+                isRunning: { $0 == pro }
+            ) == "Also open in Lanework Pro"
+        )
+
+        // And it goes away again when Pro closes the board, still without a relaunch.
+        asPro.clearOpenNow(id: id)
+        #expect(asBase.otherEditionsFlaggedOpen(id: id).isEmpty)
+    }
+}
+
+// MARK: - The awareness line
+
+@Suite("The board popover's awareness line")
+struct BoardEditionPresenceTests {
+
+    @Test("A live other edition earns the line")
+    func aLiveEditionIsNamed() {
+        #expect(
+            BoardEditionPresence.note(otherEditions: [pro], isRunning: { $0 == pro })
+                == "Also open in Lanework Pro"
+        )
+        #expect(
+            BoardEditionPresence.note(otherEditions: [base], isRunning: { _ in true })
+                == "Also open in Lanework"
+        )
+    }
+
+    @Test("A flag with no live process shows nothing — crash residue never lies")
+    func staleFlagsSayNothing() {
+        // The flag is deliberately left standing by a crash (02-architecture.md § Launch and window
+        // lifecycle — that residue is what makes crash recovery free), so the flag alone would claim
+        // an app that died last week is looking at this board right now.
+        #expect(BoardEditionPresence.note(otherEditions: [pro], isRunning: { _ in false }) == nil)
+        #expect(BoardEditionPresence.note(otherEditions: [], isRunning: { _ in true }) == nil)
+    }
+
+    @Test("An edition this build cannot name shows nothing")
+    func unknownEditionsSayNothing() {
+        #expect(
+            BoardEditionPresence.note(otherEditions: ["dev.rzen.indie.KanbanTeams"], isRunning: { _ in true })
+                == nil
+        )
+        // …and a nameable live one behind it still wins, so one unknown neighbour does not silence the
+        // line altogether.
+        #expect(
+            BoardEditionPresence.note(
+                otherEditions: ["dev.rzen.indie.KanbanTeams", pro],
+                isRunning: { _ in true }
+            ) == "Also open in Lanework Pro"
+        )
+    }
+}
+
+// MARK: - The welcome row
+
+@MainActor
+@Suite("The cross-edition welcome row")
+struct CrossEditionWelcomeRowTests {
+
+    @Test("A re-grant row opens on one click, reveals on none, and says what the click will do")
+    func theRowIsOpenableButNotRevealable() throws {
+        let record = BoardRecord(
+            grants: [pro: Data("pro's key".utf8)],
+            displayName: "Roadmap",
+            lastKnownPath: "/Boards/Roadmap.kanban",
+            lastOpened: Date()
+        )
+        let recent = RecentBoard.needsReopen(record, recordedAt: URL(fileURLWithPath: record.lastKnownPath))
+
+        let row = try #require(WelcomeRow.derive(recents: [recent], failures: []).rows.first)
+        #expect(row.needsReopen)
+        #expect(row.canOpen, "the board is there — one click plus Grant is the whole remedy")
+        #expect(!row.canReveal, "revealing a folder is a read this app has not been granted either")
+        #expect(row.caption == .needsReopen)
+        #expect(row.regrantAnchor?.path == "/Boards/Roadmap.kanban")
+        #expect(row.location == "/Boards")
+    }
+
+    @Test("Fail-fast's specifics still outrank the re-grant caption")
+    func aFailureStillWinsTheCaption() throws {
+        let record = BoardRecord(
+            grants: [pro: Data("pro's key".utf8)],
+            displayName: "Roadmap",
+            lastKnownPath: "/Boards/Roadmap.kanban",
+            lastOpened: Date()
+        )
+        let recent = RecentBoard.needsReopen(record, recordedAt: URL(fileURLWithPath: record.lastKnownPath))
+        let failure = LaunchFailure(path: "/Boards/Roadmap.kanban", message: "index.md is unparseable.")
+
+        let row = try #require(WelcomeRow.derive(recents: [recent], failures: [failure]).rows.first)
+        // The precedence 02 § Launch and window lifecycle fixes: a failure is what the row is *for* at
+        // that moment, and it is still true that this board needs granting — but the message the user
+        // has to read first is the one about the file.
+        #expect(row.caption == .failed("index.md is unparseable."))
+        #expect(row.canOpen, "and the retry is still one click")
+    }
+}
@@ -33,14 +33,19 @@ private func makeMixedBoard() throws -> WriterFixture {
    return fixture
 }

-/// An `AppModel` whose registry file lives in temp rather than in the test host's real Application
-/// Support directory.
+/// An `AppModel` whose app-side state lives in temp rather than in the shared App Group container —
+/// both halves of it: the registry file, and the clipboard's staging store, whose launch sweep would
+/// otherwise collect the developer's own staged copy (and the sibling edition's, since there is one
+/// store now).
@MainActor
 private func makeModel() throws -> (model: AppModel, tearDown: () -> Void) {
    let folder = FileManager.default.temporaryDirectory
        .appendingPathComponent("AppModelTests-\(UUID().uuidString)", isDirectory: true)
    try FileManager.default.createDirectory(at: folder, withIntermediateDirectories: true)
-    let model = AppModel(registryStorageURL: folder.appendingPathComponent("board-registry.json"))
+    let model = AppModel(
+        registryStorageURL: folder.appendingPathComponent("board-registry.json"),
+        clipboardStagingRoot: folder.appendingPathComponent("Clipboard", isDirectory: true)
+    )
    return (model, { try? FileManager.default.removeItem(at: folder) })
 }

@@ -214,13 +219,13 @@ struct AppModelTests {
        let record = try #require(model.boardRegistry.record(id: recordID))
        #expect(record.laneCount == 2, "the counts the welcome row will show are the working ones")
        #expect(record.cardCount == 2)
-        #expect(record.isOpenNow == false)
+        #expect(!record.isOpen(inEdition: model.boardRegistry.editionID))
        #expect(model.boardRegistry.restorables().isEmpty)

        // Twice is a no-op, which is what lets the window's close interception and its disappear both
        // call this without the sequence running twice.
        await model.closeBoard(ref: ref, cause: .userClose)
-        #expect(model.boardRegistry.record(id: recordID)?.isOpenNow == false)
+        #expect(model.boardRegistry.record(id: recordID)?.isOpen(inEdition: model.boardRegistry.editionID) == false)
    }

    @Test("Quit closes every board and leaves them all flagged for the next launch")
@@ -91,7 +91,7 @@ struct BoardRegistryTests {

        let id = registry.recordOpen(of: fixture.root, displayName: "Todo Board")
        let created = try #require(registry.record(id: id))
-        #expect(!created.bookmark.isEmpty)
+        #expect(created.grant(forEdition: registry.editionID) != nil)
        #expect(created.displayName == "Todo Board")
        #expect(created.lastKnownPath == fixture.root.path)
        #expect(created.laneCount == nil, "counts are stamped at close, never guessed at open")
@@ -135,7 +135,7 @@ struct BoardRegistryTests {
        let id = registry.recordOpen(of: fixture.root)
        let record = try #require(registry.record(id: id))
        #expect(record.displayName == fixture.root.deletingPathExtension().lastPathComponent)
-        #expect(!record.bookmark.isEmpty, "the bookmark still mints on the before-load call")
+        #expect(record.grant(forEdition: registry.editionID) != nil, "the bookmark still mints on the before-load call")
        #expect(record.icon == nil)
        #expect(record.iconColor == nil)
    }
@@ -163,7 +163,7 @@ struct BoardRegistryTests {
        #expect(record.icon == "star")
        #expect(record.iconColor == "fern")
        #expect(record.lastOpened > firstOpened, "the bookmark and lastOpened still refresh on every open attempt")
-        #expect(!record.bookmark.isEmpty)
+        #expect(record.grant(forEdition: registry.editionID) != nil)
    }

    // MARK: Counts
@@ -620,16 +620,16 @@ struct BoardRegistryTests {
        let registry = BoardRegistry(storageURL: storage.url)

        let id = registry.recordOpen(of: fixture.root, displayName: "Work")
-        #expect(registry.record(id: id)?.isOpenNow == nil, "recording an open is not opening a window")
+        #expect(registry.record(id: id)?.isOpen(inEdition: registry.editionID) == false, "recording an open is not opening a window")
        #expect(registry.restorables().isEmpty)

        registry.setOpenNow(id: id)
-        #expect(registry.record(id: id)?.isOpenNow == true)
+        #expect(registry.record(id: id)?.isOpen(inEdition: registry.editionID) == true)
        #expect(ids(registry.restorables()) == [id])

        // A user close. The flag goes, and with it the board's place in the next launch.
        registry.clearOpenNow(id: id)
-        #expect(registry.record(id: id)?.isOpenNow == false)
+        #expect(registry.record(id: id)?.isOpen(inEdition: registry.editionID) == false)
        #expect(registry.restorables().isEmpty)

        // A quit. The teardown stamps counts and does *not* clear the flag — that omission is the
@@ -639,7 +639,7 @@ struct BoardRegistryTests {
        registry.recordClose(id: id, displayName: "Work", laneCount: 2, cardCount: 5)

        let afterRelaunch = BoardRegistry(storageURL: storage.url)
-        #expect(afterRelaunch.record(id: id)?.isOpenNow == true, "the flags describe what was open at quit")
+        #expect(afterRelaunch.record(id: id)?.isOpen(inEdition: registry.editionID) == true, "the flags describe what was open at quit")
        #expect(ids(afterRelaunch.restorables()) == [id])
        #expect(afterRelaunch.record(id: id)?.laneCount == 2)
    }
@@ -712,13 +712,13 @@ struct BoardRegistryTests {

        let registry = BoardRegistry(storageURL: storage.url)
        #expect(registry.recents().count == 1, "the file decoded; nothing was quarantined")
-        #expect(registry.record(id: id)?.isOpenNow == nil, "a missing key reads as 'not open'")
+        #expect(registry.record(id: id)?.isOpen(inEdition: registry.editionID) == false, "a missing key reads as 'not open'")
        #expect(registry.restorables().isEmpty)
        #expect(registry.record(id: id)?.laneCount == 4, "and every other field survived")

        // And the key writes through from here on.
        registry.setOpenNow(id: id)
-        #expect(BoardRegistry(storageURL: storage.url).record(id: id)?.isOpenNow == true)
+        #expect(BoardRegistry(storageURL: storage.url).record(id: id)?.isOpen(inEdition: registry.editionID) == true)
    }

    // MARK: Bookmarks in a sandboxed host
@@ -230,7 +230,7 @@ struct TemplateChooserRowTests {
 // MARK: - Fixture

 /// A temp store holding hand-written template board folders — the user store's shape, minus
-/// Application Support (which no test may touch).
+/// the shared App Group container (which no test may touch).
 struct TemplateFixture {

    let store: URL
@@ -43,7 +43,7 @@ private func subtitle(forCard cardID: String, boardNamed board: String, in model
    return CardWindowHost.subtitle(board: board, lane: placement.lane.title.value)
 }

-/// A registry whose file lives in temp rather than in the test host's Application Support.
+/// A registry whose file lives in temp rather than in the shared App Group container.
@MainActor
 private struct RegistryStorage {
    let folder: URL
@@ -264,7 +264,10 @@ struct CardWindowIdentityTests {
        let storage = try RegistryStorage()
        defer { storage.tearDown() }

-        let model = AppModel(registryStorageURL: storage.url)
+        let model = AppModel(
+            registryStorageURL: storage.url,
+            clipboardStagingRoot: storage.folder.appendingPathComponent("Clipboard", isDirectory: true)
+        )
        let board = BoardWindowRef(url: fixture.root)
        let recordID = model.boardRegistry.recordOpen(of: fixture.root)
        let store = try model.storeRegistry.acquire(fixture.root)
@@ -8,8 +8,9 @@ import Testing
 ///
 /// Every suite here drives a real store over a real temp board, with two things injected: a fake
 /// pasteboard (so a test never races the machine's one real pasteboard, nor every other test in the
-/// run) and a temp staging directory (so nothing goes near Application Support). Both seams exist
-/// exactly because those two claims are the ones worth pinning.
+/// run) and a temp staging directory (so nothing goes near the shared App Group container, which is now
+/// the sibling edition's staging store too). Both seams exist exactly because those two claims are the
+/// ones worth pinning.

 // MARK: - Test doubles

@@ -109,8 +110,14 @@ struct ClipboardHarness {
    }

    /// The staged copy directories, sorted — "at most the current copy" is a claim about this list.
+    ///
+    /// Hidden entries are excluded because the sweep keeps its own bookkeeping folder among them
+    /// (`ClipboardStore.prune`'s claim-then-delete, which is what makes a concurrent sweep by the
+    /// sibling edition safe). A staged copy is never hidden — its name is a lowercased UUID.
    func stagedCopyIDs() throws -> [String] {
-        try FileManager.default.contentsOfDirectory(atPath: staging.path).sorted()
+        try FileManager.default.contentsOfDirectory(atPath: staging.path)
+            .filter { !$0.hasPrefix(".") }
+            .sorted()
    }
 }

@@ -389,6 +396,106 @@ struct ClipboardSweepTests {

        #expect(try harness.stagedCopyIDs().isEmpty)
    }
+
+    // MARK: The sibling edition's sweep
+    //
+    // The staging store now lives in the shared App Group container (12-editions.md ▸ Both editions
+    // installed), so base and Pro sweep the same directory on their own launches, activations, copies
+    // and pastes. Both compute the *same* answer — the keep set is the one `copyID` the machine-wide
+    // pasteboard names — so they never disagree about what should go; what they can do is arrive at the
+    // same doomed tree together. These two tests are the ruling's two clauses: atomic removals, and
+    // missing-entry = already swept.
+
+    @Test("Two editions sweeping the same store at once agree, and neither errors")
+    func concurrentSweepsFromBothEditionsAgree() async throws {
+        let staging = FileManager.default.temporaryDirectory
+            .appendingPathComponent("ClipboardTests-\(UUID().uuidString)", isDirectory: true)
+        defer { try? FileManager.default.removeItem(at: staging) }
+        try FileManager.default.createDirectory(at: staging, withIntermediateDirectories: true)
+
+        // Six trees, each with a file in it so a removal is a real recursive delete rather than an
+        // empty-directory unlink — the case where two sweepers walking one tree could see it half gone.
+        for name in ["a", "b", "c", "d", "e", "keep"] {
+            let tree = staging.appendingPathComponent(name, isDirectory: true)
+            try FileManager.default.createDirectory(
+                at: tree.appendingPathComponent("nested", isDirectory: true),
+                withIntermediateDirectories: true
+            )
+            try Data("bytes".utf8).write(to: tree.appendingPathComponent("nested/file.txt", isDirectory: false))
+        }
+
+        // Both editions read the *same* pasteboard, which is why both keep sets are `keep`. Modelled as
+        // two stores over one staging root with pasteboards holding the same manifest, since two
+        // processes are not something a unit test can have.
+        let manifest = ClipboardManifest(
+            copyID: "keep",
+            boardRoot: URL(fileURLWithPath: "/Boards/Shared.kanban", isDirectory: true),
+            kind: .card,
+            container: .board,
+            // One entry, because a manifest with none is refused outright (`init?(data:)`) — and a
+            // refused manifest is a keep set of nothing, which is a different test.
+            entries: [
+                ClipboardManifest.Entry(
+                    id: Ident.card1,
+                    folder: Ident.card1,
+                    title: "First",
+                    index: "---\nschema: 1\ntitle: First\norder: 1024\n---\n",
+                    attachmentCount: 0
+                )
+            ]
+        )
+        let data = try #require(manifest.encoded())
+
+        let onePasteboard = FakePasteboard()
+        onePasteboard.write(manifest: data, text: manifest.plainText)
+        let otherPasteboard = FakePasteboard()
+        otherPasteboard.write(manifest: data, text: manifest.plainText)
+
+        // Each `init` sweeps — the launch sweep — so the two are already racing before either explicit
+        // call below.
+        let one = ClipboardStore(pasteboard: onePasteboard, stagingRoot: staging, observesActivation: false)
+        let other = ClipboardStore(pasteboard: otherPasteboard, stagingRoot: staging, observesActivation: false)
+        one.sweep()
+        other.sweep()
+        one.sweep()
+        await one.stagingSettled()
+        await other.stagingSettled()
+
+        // The answer both computed, arrived at exactly once: the named tree intact, everything else
+        // gone, and no bookkeeping left behind.
+        #expect(try FileManager.default.contentsOfDirectory(atPath: staging.path).sorted() == ["keep"])
+        #expect(FileManager.default.fileExists(atPath: staging.appendingPathComponent("keep/nested/file.txt").path))
+    }
+
+    @Test("A tree that vanished before the sweep reached it is already swept, not an error")
+    func aVanishedEntryIsANoOp() async throws {
+        let staging = FileManager.default.temporaryDirectory
+            .appendingPathComponent("ClipboardTests-\(UUID().uuidString)", isDirectory: true)
+        defer { try? FileManager.default.removeItem(at: staging) }
+        try FileManager.default.createDirectory(at: staging, withIntermediateDirectories: true)
+        let doomed = staging.appendingPathComponent("gone", isDirectory: true)
+        try FileManager.default.createDirectory(at: doomed, withIntermediateDirectories: true)
+
+        let clipboard = ClipboardStore(
+            pasteboard: FakePasteboard(),
+            stagingRoot: staging,
+            observesActivation: false
+        )
+        // The sibling got there first — which from this store's side is indistinguishable from the
+        // directory listing simply being stale by the time it is walked.
+        try FileManager.default.removeItem(at: doomed)
+        clipboard.sweep()
+        await clipboard.stagingSettled()
+
+        #expect(try FileManager.default.contentsOfDirectory(atPath: staging.path).isEmpty)
+
+        // And a staging root that has gone altogether — the sibling swept, then something removed the
+        // shared folder — is nothing to do either, rather than a throw on the way to a no-op.
+        try FileManager.default.removeItem(at: staging)
+        clipboard.sweep()
+        await clipboard.stagingSettled()
+        #expect(!FileManager.default.fileExists(atPath: staging.path), "a vanished store is not recreated by a sweep")
+    }
 }

 // MARK: - Takeover
@@ -464,7 +464,10 @@ private func makeModel() throws -> (model: AppModel, tearDown: () -> Void) {
    let folder = FileManager.default.temporaryDirectory
        .appendingPathComponent("HistoryProviderTests-\(UUID().uuidString)", isDirectory: true)
    try FileManager.default.createDirectory(at: folder, withIntermediateDirectories: true)
-    let model = AppModel(registryStorageURL: folder.appendingPathComponent("board-registry.json"))
+    let model = AppModel(
+        registryStorageURL: folder.appendingPathComponent("board-registry.json"),
+        clipboardStagingRoot: folder.appendingPathComponent("Clipboard", isDirectory: true)
+    )
    return (model, { try? FileManager.default.removeItem(at: folder) })
 }

@@ -19,8 +19,9 @@ import Testing
 ///
 /// Plus the promise that makes the copy safe to run at all: a cancelled save leaves nothing behind.
 ///
-/// Every test drives an explicit store URL. **No test may touch Application Support** — `userStore`
-/// is named here only to prove the engine never creates it on its own.
+/// Every test drives an explicit store URL. **No test may touch the real store** — which since the
+/// 2026-07-29 re-homing is in the shared App Group container, so it would be the sibling edition's
+/// template store too. `userStore` is named here only to prove the engine never creates it on its own.

 // MARK: - Helpers

@@ -438,14 +439,18 @@ struct SaveAsTemplateAtomicityTests {
@Suite("Save as Template — the user store")
 struct UserTemplateStoreTests {

-    @Test("The user store is named inside the app container and is never created by naming it")
+    @Test("The user store is named beside the registry in the shared home, and is never created by naming it")
    func theStoreIsNamedNotCreated() {
        let store = TemplateEngine.userStore

        #expect(store.lastPathComponent == TemplateEngine.storeFolderName)
-        #expect(store.deletingLastPathComponent().lastPathComponent
-                    == (Bundle.main.bundleIdentifier ?? "dev.rzen.indie.Kanban"))
-        #expect(store.path.contains("Application Support"))
+        // Beside the registry and the clipboard's staging store, in the App Group container
+        // (09-templates.md ▸ Storage, re-homed 2026-07-29 — templates cross editions). Compared against
+        // the one shared home rather than spelled out, so the assertion follows it wherever it goes —
+        // including the scratch redirect a test host gets (`AppGroup.isUnitTestHost`). `AppGroup` rather
+        // than the two stores' own defaults because those are `@MainActor` and this suite is not; that
+        // the three agree is `AppGroupContainerTests`' assertion.
+        #expect(store.deletingLastPathComponent() == AppGroup.stateDirectory)
        // Nothing here creates it, and no test may: `createUserStore(at:)` is Save as Template's and
        // Reveal in Finder's, and both are driven with an explicit store in this suite.
    }
@@ -15,8 +15,8 @@ import Testing

 // MARK: - Fixtures

-/// A record with nothing in it that matters except what a given test is about. The bookmark is empty
-/// because this function never resolves one — `RecentBoard` is constructed directly here, so the
+/// A record with nothing in it that matters except what a given test is about. It holds **no grant
+/// slot** because this function never resolves one — `RecentBoard` is constructed directly here, so the
 /// availability classification is an input rather than a filesystem outcome.
 private func record(
    name: String,
@@ -28,7 +28,6 @@ private func record(
    iconColor: String? = nil
 ) -> BoardRecord {
    BoardRecord(
-        bookmark: Data(),
        displayName: name,
        lastKnownPath: path,
        lastOpened: opened,
@@ -144,7 +144,8 @@ fi

 for key in com.apple.security.app-sandbox \
           com.apple.security.files.user-selected.read-write \
-           com.apple.security.files.bookmarks.app-scope; do
+           com.apple.security.files.bookmarks.app-scope \
+           com.apple.security.application-groups; do
    if has_entitlement "$BASE_APP" "$key"; then
        pass "base carries $key"
    else
@@ -164,7 +165,7 @@ done
 #                                      archive — which is why they are named out loud below rather
 #                                      than quietly filtered.
 toolchain_injected='^(com\.apple\.security\.get-task-allow|com\.apple\.application-identifier|com\.apple\.developer\.team-identifier|com\.apple\.security\.temporary-exception\.[a-z.-]*)$'
-settled_minimum='^(com\.apple\.security\.app-sandbox|com\.apple\.security\.files\.user-selected\.read-write|com\.apple\.security\.files\.bookmarks\.app-scope)$'
+settled_minimum='^(com\.apple\.security\.app-sandbox|com\.apple\.security\.files\.user-selected\.read-write|com\.apple\.security\.files\.bookmarks\.app-scope|com\.apple\.security\.application-groups)$'

 base_extra="$(entitlement_keys "$BASE_APP" | grep -vE "$settled_minimum" | grep -vE "$toolchain_injected")"
 if [ -n "$base_extra" ]; then
@@ -187,6 +188,7 @@ head2 "Pro — entitlements"
 for key in com.apple.security.app-sandbox \
           com.apple.security.files.user-selected.read-write \
           com.apple.security.files.bookmarks.app-scope \
+           com.apple.security.application-groups \
           com.apple.security.network.client \
           keychain-access-groups; do
    if has_entitlement "$PRO_APP" "$key"; then
@@ -196,6 +198,45 @@ for key in com.apple.security.app-sandbox \
    fi
 done

+# ------------------------------------------------------------------------------ the App Group
+#
+# 12-editions.md ▸ Distribution (ruled 2026-07-29): "every edition declares the family group —
+# `group.dev.rzen.indie.Kanban` — and the board registry with its Application Support peers homes in
+# the group container **from day one**". The upgrade story is exactly this string matching across the
+# two signatures: an edition declaring a group of its own would share nothing while looking as though
+# it did, and nothing in the app could detect the difference — the container would simply be empty.
+
+head2 "The App Group — one container, either app"
+
+# The group ids the signature declares, one per line. Read from the signature rather than the source
+# `.entitlements` for the reason every check here does: the shipped binary is the claim.
+#
+# `sed` over the whole stream rather than a line-oriented pass, because `codesign --xml` emits the
+# entire plist on **one line** — which is also why `entitlement_keys` above reaches for `grep -o`
+# instead of PlistBuddy. The two substitutions trim everything before this key's `<array>` and
+# everything after its close, leaving only its own `<string>`s to unwrap.
+app_groups() {
+    entitlements_of "$1" |
+        sed -e 's/.*<key>com\.apple\.security\.application-groups<\/key><array>//' \
+            -e 's/<\/array>.*//' |
+        grep -o '<string>[^<]*</string>' |
+        sed 's/<[^>]*>//g'
+}
+
+expected_group="group.dev.rzen.indie.Kanban"
+base_groups="$(app_groups "$BASE_APP")"
+pro_groups="$(app_groups "$PRO_APP")"
+
+for app_label in "base:$base_groups" "pro:$pro_groups"; do
+    label="${app_label%%:*}"
+    groups="${app_label#*:}"
+    if [ "$groups" = "$expected_group" ]; then
+        pass "$label declares exactly $expected_group"
+    else
+        fail "$label declares '$groups', expected '$expected_group'"
+    fi
+done
+
 # ------------------------------------------------------------------------------ bundle identity

 head2 "Bundle identity"