test: launch-paths BLOCKER regression + isWritableDirectory unit tests

ReturnWatcherTests.swift: two new tests bracket the BLOCKER fix — one
characterizes the old bug (FolderSettings.resolvedAppSupportPaths(), AirDrop-
only, ignores the persisted OneDrive transport; the watcher ends up watching
a stale isolated folder and misses a marked PDF dropped into the real
OneDrive-mode folder), the other proves the fix (the exact launch/bootstrap
construction — TransportSettings.resolvedAppSupportPaths() +
watcher.updateWatchFolder() before start — detects it). Both isolated to
temp dirs, including an explicit FolderSettings watch-folder override so the
"bug" test's found.isEmpty assertion never depends on what's actually in
Ben's real ~/Downloads (it does, in fact, already contain real marked-up
Redline PDFs from prior testing — an earlier version of this test read the
REAL Downloads folder and failed for exactly that reason).

TransportSettingsTests.swift: three tests for
OneDriveLocator.isWritableDirectory — true for an ordinary directory, false
for one chmod'd 500 (permissions restored in teardown before removal), false
for a plain file and for a nonexistent path.

Co-Authored-By: Claude Fable 5.1 <noreply@anthropic.com>
Claude-Session: https://claude.ai/code/session_012ZiTXPbPCSjzPVsfoweAbp

Sources/Shotdeck/AppModel.swift

@@ -132,6 +132,13 @@ public final class AppModel {
     }
     func setTransport(_ value: SendTransport) { transport = value }
     func setResolvedOneDriveFolder(_ value: URL?) { resolvedOneDriveFolder = value }
+
+    /// Bumped by chooseTransport/chooseOneDriveFolder (SettingsView.swift) before each
+    /// spawns its async watcher-reconcile Task; that Task checks its own snapshot
+    /// against the live value before every mutating step, so rapid toggling always
+    /// lets the LAST choice win instead of applying stale, superseded work. Not
+    /// `@Observable`-relevant state — pure internal bookkeeping, never read by a View.
+    var reconcileGeneration = 0
     func rememberLastComposedPDF(_ url: URL) { lastComposedPDFURL = url }
 
     /// True when a last-composed PDF path is known this run, or the newest
@@ -211,6 +218,17 @@ public final class AppModel {
         await watcher.setRecordUncommented(transport == .airDrop)
 
         do {
+            // BLOCKER fix: reconcile the watcher's internal watchFolder with the live
+            // watchFolderURL UNCONDITIONALLY, before it ever starts. `paths` (and so the
+            // watcher's initial folder, set in its own init) now comes from the same
+            // transport-aware TransportSettings.effectiveFolders() as watchFolderURL, so
+            // in the normal case this is a no-op — but it is the only thing that would
+            // have caught the old bug (launch paths built AirDrop-only while OneDrive was
+            // the persisted transport, leaving the watcher's FSEvents stream pointed at a
+            // stale folder for the whole session) and it stays cheap insurance against
+            // that class of drift ever recurring. Calling it before start() only updates
+            // the stored folder — no FSEvents stream exists yet to restart.
+            try await watcher.updateWatchFolder(watchFolderURL)
             try await watcher.start { [weak self] _ in
                 Task { @MainActor in
                     guard let self else { return }

Sources/Shotdeck/PickerSelfTest.swift

@@ -223,7 +223,7 @@ enum PickerSelfTest {
             sendTruthFail("seeded session was empty")
         }
 
-        let pending = try await model.composePDFForSend()
+        let pending = try await model.composePDFForSend(outbox: model.outboxURL)
         guard fm.fileExists(atPath: pending.fileURL.path) else {
             sendTruthFail("PDF was not written")
         }
@@ -476,18 +476,13 @@ enum PickerSelfTest {
         exit(1)
     }
 
-    /// Real sync root this Mac has; the phase proves the transport against the actual
+    /// Phase 5: proves the OneDrive transport end to end against a REAL sync root —
-    /// OneDrive file provider, never a fake home tree (that is what
+    /// resolved at runtime via `OneDriveLocator.syncRoots()`, never a hardcoded path, so
-    /// OneDriveLocatorTests in ShotdeckCoreTests are for).
+    /// this runs correctly on any Mac/account that has OneDrive signed in (MMD-named
-    private static let realOneDriveSyncRoot = URL(
+    /// root preferred, same as production). Triggered by `SHOTDECK_ONEDRIVE_SELFTEST`
-        fileURLWithPath: "/Users/benjaminhippler/Library/CloudStorage/OneDrive-MMDGROUP",
+    /// when chained after PICKER/SEND-TRUTH/UPDATE-SELFTEST — the exact pattern
-        isDirectory: true
+    /// `startUpdateSelfTestIfRequested` uses for its own env var. Returns true when the
-    )
+    /// async phase was scheduled (it calls `exit` itself).
-
-    /// Phase 5: proves the OneDrive transport end to end against the real sync root.
-    /// Triggered by `SHOTDECK_ONEDRIVE_SELFTEST` when chained after PICKER/SEND-TRUTH/
-    /// UPDATE-SELFTEST — the exact pattern `startUpdateSelfTestIfRequested` uses for its
-    /// own env var. Returns true when the async phase was scheduled (it calls `exit` itself).
     @discardableResult
     private static func startOneDriveSelfTestIfRequested() -> Bool {
         guard ProcessInfo.processInfo.environment["SHOTDECK_ONEDRIVE_SELFTEST"] != nil else {
@@ -514,9 +509,16 @@ enum PickerSelfTest {
     }
 
     private static func runOneDriveSelfTestAndExit() {
+        // Never a false PASS: no real OneDrive sync root on this machine/account is a
+        // SKIP (still non-zero exit), not silently treated as passing.
+        guard let syncRoot = OneDriveLocator.syncRoots().first else {
+            print("ONEDRIVE-SELFTEST SKIP no OneDrive sync root")
+            fflush(stdout)
+            exit(1)
+        }
         Task { @MainActor in
             do {
-                let folder = try await executeOneDriveSelfTest()
+                let folder = try await executeOneDriveSelfTest(syncRoot: syncRoot)
                 print("ONEDRIVE-SELFTEST PASS path=\(folder.path)")
                 fflush(stdout)
                 exit(0)
@@ -528,19 +530,30 @@ enum PickerSelfTest {
         }
     }
 
-    /// Builds a session, sends it through the OneDrive branch of `send(anchor: nil)`
+    /// Sub-step 1: builds a session, sends it through the OneDrive branch of
-    /// against a NEW folder under the real OneDrive sync root, confirms the watcher does
+    /// `send(anchor: nil)` against a NEW folder under `syncRoot`, confirms the watcher
-    /// NOT report the freshly-written unmarked PDF as a return, then adds a real PDFKit
+    /// does NOT report the freshly-written unmarked PDF as a return, then adds a real
-    /// ink annotation in place (what the iPad does) and confirms the watcher now reports
+    /// PDFKit ink annotation in place (what the iPad does) and confirms the watcher now
-    /// it as commented. Never deletes anything under OneDrive — the created folder and
+    /// reports it as commented.
-    /// PDF are left in place for Ben to inspect / for the real iPad round trip.
+    ///
-    private static func executeOneDriveSelfTest() async throws -> URL {
+    /// Sub-step 1b: rapid transport toggling (chooseTransport(.airDrop) immediately
+    /// followed by chooseTransport(.oneDrive), no await between them) must still end
+    /// with the watcher pointed at the OneDrive folder — proves the generation-guarded
+    /// reconcile in chooseTransport/chooseOneDriveFolder (SettingsView.swift) really
+    /// does let the last choice win instead of an earlier, superseded call applying its
+    /// stale folder after a later one already won.
+    ///
+    /// Sub-step 2: relaunch simulation — the exact BLOCKER scenario this phase exists to
+    /// catch. OneDrive is still persisted in defaults from sub-step 1; builds a FRESH
+    /// model the same way the real app launches (`AppDelegate.makeLaunchModel()` itself,
+    /// not a reimplementation), bootstraps it, then marks a PDF in the folder in place —
+    /// the relaunched watcher must report it. A temp app-support root keeps this off the
+    /// real ~/Library/Application Support/Shotdeck.
+    ///
+    /// Never deletes anything under OneDrive — the created folder and PDFs are left in
+    /// place for Ben to inspect / for the real iPad round trip.
+    private static func executeOneDriveSelfTest(syncRoot: URL) async throws -> URL {
         let fm = FileManager.default
-        guard fm.fileExists(atPath: realOneDriveSyncRoot.path) else {
-            throw OneDriveSelfTestError.detail(
-                "real OneDrive sync root not found at \(realOneDriveSyncRoot.path)"
-            )
-        }
 
         // UserDefaults.standard is the ONLY defaults instance send()/TransportSettings
         // actually read at runtime (there is no defaults-threading through AppModel), so
@@ -563,8 +576,7 @@ enum PickerSelfTest {
         }
 
         let stamp = DubaiTime.fileStamp(Date())
-        let selftestFolder = realOneDriveSyncRoot
+        let selftestFolder = syncRoot.appendingPathComponent("Redline-selftest-\(stamp)", isDirectory: true)
-            .appendingPathComponent("Redline-selftest-\(stamp)", isDirectory: true)
         try fm.createDirectory(at: selftestFolder, withIntermediateDirectories: true)
 
         TransportSettings.setTransport(.oneDrive, defaults: defaults)
@@ -629,8 +641,77 @@ enum PickerSelfTest {
         }
 
         // What the iPad does: mark it up in place with a real ink annotation, then save.
-        guard let document = PDFDocument(url: pdfURL), let page = document.page(at: 0) else {
+        try addInkMark(to: pdfURL)
-            throw OneDriveSelfTestError.detail("could not reopen \(pdfURL.path) to annotate it")
+
+        let afterMarkup = try await watcher.scanNow()
+        guard let recorded = afterMarkup.first(where: { $0.fileURL == pdfURL }), recorded.isCommented else {
+            throw OneDriveSelfTestError.detail("annotated PDF was not reported as commented by scanNow")
+        }
+        let commentedAfter = try await ledger.commented()
+        guard commentedAfter.contains(where: { $0.fileURL == pdfURL }) else {
+            throw OneDriveSelfTestError.detail("annotated PDF was not recorded in the ledger as commented")
+        }
+
+        // Sub-step 1b: rapid toggle race — see the doc comment above this function.
+        model.chooseTransport(.airDrop)
+        model.chooseTransport(.oneDrive)   // immediately superseding the call above
+        // The generation guard itself is what's under test, not this wait — it just
+        // gives the (already-guarded) reconcile Task a moment to settle either way.
+        try await Task.sleep(for: .milliseconds(500))
+        guard model.transport == .oneDrive else {
+            throw OneDriveSelfTestError.detail(
+                "rapid toggle: model.transport ended as \(model.transport), expected .oneDrive"
+            )
+        }
+        let racePDFURL = selftestFolder.appendingPathComponent("Redline-race-\(stamp).pdf")
+        try writeUnmarkedRedlinePDF(to: racePDFURL)
+        try addInkMark(to: racePDFURL)
+        let raceFound = try await model.watcher.scanNow()
+        guard raceFound.first(where: { $0.fileURL == racePDFURL })?.isCommented == true else {
+            throw OneDriveSelfTestError.detail(
+                "rapid toggle: watcher did not end up watching \(selftestFolder.path) — an earlier, superseded chooseTransport call won"
+            )
+        }
+
+        // Sub-step 2: relaunch simulation — see the doc comment above this function.
+        let relaunchAppSupportRoot = fm.temporaryDirectory
+            .appendingPathComponent("shotdeck-onedrive-relaunch-\(UUID().uuidString)", isDirectory: true)
+        defer { try? fm.removeItem(at: relaunchAppSupportRoot) }
+
+        let relaunchModel = AppDelegate.makeLaunchModel(appSupportRoot: relaunchAppSupportRoot)
+        guard relaunchModel.transport == .oneDrive else {
+            throw OneDriveSelfTestError.detail(
+                "relaunch: model transport was \(relaunchModel.transport), expected .oneDrive"
+            )
+        }
+        guard relaunchModel.watchFolderURL.path == selftestFolder.path else {
+            throw OneDriveSelfTestError.detail(
+                "relaunch: model watchFolderURL was \(relaunchModel.watchFolderURL.path), expected \(selftestFolder.path) — this is the exact BLOCKER this phase guards against"
+            )
+        }
+
+        await relaunchModel.bootstrap()
+
+        let relaunchPDFURL = selftestFolder.appendingPathComponent("Redline-relaunch-\(stamp).pdf")
+        try writeUnmarkedRedlinePDF(to: relaunchPDFURL)
+        try addInkMark(to: relaunchPDFURL)
+
+        let relaunchFound = try await relaunchModel.watcher.scanNow()
+        guard relaunchFound.first(where: { $0.fileURL == relaunchPDFURL })?.isCommented == true else {
+            throw OneDriveSelfTestError.detail(
+                "relaunch: watcher did not report the marked PDF at \(relaunchPDFURL.path) as returned — it was watching the wrong folder after relaunch"
+            )
+        }
+        await relaunchModel.watcher.stop()
+
+        return selftestFolder
+    }
+
+    /// Adds a real PDFKit ink annotation to the PDF at `url` in place and saves it —
+    /// exactly what the iPad does when marking up a page.
+    private static func addInkMark(to url: URL) throws {
+        guard let document = PDFDocument(url: url), let page = document.page(at: 0) else {
+            throw OneDriveSelfTestError.detail("could not reopen \(url.path) to annotate it")
         }
         let ink = PDFAnnotation(
             bounds: CGRect(x: 20, y: 20, width: 60, height: 60),
@@ -642,20 +723,27 @@ enum PickerSelfTest {
         stroke.line(to: NSPoint(x: 80, y: 80))
         ink.add(stroke)
         page.addAnnotation(ink)
-        guard document.write(to: pdfURL) else {
+        guard document.write(to: url) else {
-            throw OneDriveSelfTestError.detail("could not save the annotated PDF back to \(pdfURL.path)")
+            throw OneDriveSelfTestError.detail("could not save the annotated PDF back to \(url.path)")
+        }
     }
 
-        let afterMarkup = try await watcher.scanNow()
+    /// Writes a fresh, unmarked, single-page "Redline"-creator PDF straight to `url` —
-        guard let recorded = afterMarkup.first(where: { $0.fileURL == pdfURL }), recorded.isCommented else {
+    /// standing in for a PDF that has just landed in the watch folder, before any
-            throw OneDriveSelfTestError.detail("annotated PDF was not reported as commented by scanNow")
+    /// human mark. Used by the rapid-toggle and relaunch sub-steps, which don't need to
+    /// exercise send()/composePDFForSend() again (sub-step 1 already does).
+    private static func writeUnmarkedRedlinePDF(to url: URL) throws {
+        let document = PDFDocument()
+        let page = PDFPage()
+        page.setBounds(CGRect(x: 0, y: 0, width: 612, height: 792), for: .mediaBox)
+        document.insert(page, at: 0)
+        document.documentAttributes = [
+            PDFDocumentAttribute.creatorAttribute: "Redline",
+            PDFDocumentAttribute.subjectAttribute: UUID().uuidString,
+        ]
+        guard document.write(to: url) else {
+            throw OneDriveSelfTestError.detail("could not write \(url.path)")
         }
-        let commentedAfter = try await ledger.commented()
-        guard commentedAfter.contains(where: { $0.fileURL == pdfURL }) else {
-            throw OneDriveSelfTestError.detail("annotated PDF was not recorded in the ledger as commented")
-        }
-
-        return selftestFolder
     }
 
     private static func oneDriveFail(_ detail: String) -> Never {

Sources/Shotdeck/SendController.swift

@@ -16,17 +16,28 @@ extension AppModel: SendCapable {
         guard !session.isEmpty, !isSending else { return }
         setSending(true)
 
+        // Snapshot BOTH the transport AND the destination folder into local `let`s
+        // ONCE, before any `await` in this function. chooseTransport/chooseOneDriveFolder
+        // now refuse (status "Finish the current send first.") while isSending is true,
+        // but this snapshot is the actual fix for the race: even without that guard,
+        // everything below operates on these frozen values — composePDFForSend(outbox:)
+        // takes the folder as a parameter and never re-reads `self.outboxURL` after a
+        // suspension point, so a concurrent transport switch mid-send can no longer land
+        // the PDF under one transport's folder while the archive/status branch (which
+        // switches on the same frozen `transport` local) runs the other's.
         let transport = TransportSettings.transport()
+        let destinationFolder: URL
 
-        // OneDrive mode: verify the real destination exists RIGHT NOW, before composing
+        // OneDrive mode: verify the real destination exists AND is writable RIGHT NOW,
-        // anything. `outboxURL` is kept in sync with the resolved OneDrive folder by
+        // before composing anything. `outboxURL` is kept in sync with the resolved
-        // bootstrap/chooseTransport/chooseOneDriveFolder, but this is re-resolved fresh
+        // OneDrive folder by bootstrap/chooseTransport/chooseOneDriveFolder, but this is
-        // here (never trusted stale) so a folder that vanished since then (OneDrive
+        // re-resolved fresh here (never trusted stale) so a folder that vanished or lost
-        // signed out, external volume unmounted, folder deleted) is caught instead of
+        // its permissions since then (OneDrive signed out, external volume unmounted,
-        // silently writing into whatever `outboxURL` happens to hold.
+        // folder deleted, chmod'd unwritable) is caught instead of silently attempted
+        // and surfacing as a generic PDF-composition failure.
         if transport == .oneDrive {
             guard let folder = OneDriveLocator.resolveOneDriveFolder(),
-                  Self.directoryExists(at: folder)
+                  OneDriveLocator.isWritableDirectory(at: folder)
             else {
                 let path = OneDriveLocator.resolveOneDriveFolder()?.path
                     ?? TransportSettings.storedOneDriveFolderPath()
@@ -36,16 +47,19 @@ extension AppModel: SendCapable {
                 setSending(false)
                 return
             }
+            destinationFolder = folder
             setResolvedOneDriveFolder(folder)
             if outboxURL != folder || watchFolderURL != folder {
                 setFolderURLs(outbox: folder, watch: folder)
                 try? await watcher.updateWatchFolder(folder)
             }
+        } else {
+            destinationFolder = outboxURL
         }
 
         let pending: ComposedSend
         do {
-            pending = try await composePDFForSend()
+            pending = try await composePDFForSend(outbox: destinationFolder)
         } catch {
             // Never unlink the published PDF, and never unlink the temp file either:
             // a rename failure would leave the complete document at the temp name.
@@ -93,19 +107,14 @@ extension AppModel: SendCapable {
         }
     }
 
-    private static func directoryExists(at url: URL) -> Bool {
+    /// Writes the PDF to `outboxDir` and records its path. Does not archive the session
-        var isDirectory: ObjCBool = false
-        let exists = FileManager.default.fileExists(atPath: url.path, isDirectory: &isDirectory)
-        return exists && isDirectory.boolValue
-    }
-
-    /// Writes the PDF to the outbox and records its path. Does not archive the session
     /// and does not present AirDrop — that happens only after the share completes.
-    func composePDFForSend() async throws -> ComposedSend {
+    /// `outboxDir` is passed in (a value `send(anchor:)` snapshotted before any await)
+    /// rather than read from `self.outboxURL` here, so a concurrent transport switch
+    /// mid-send can never redirect an in-flight compose to a different folder.
+    func composePDFForSend(outbox outboxDir: URL) async throws -> ComposedSend {
         let workingSession = session
         let composer = self.composer
-        // Live outbox (FolderSettings), not `paths.outbox` — Settings changes take effect.
-        let outboxDir = outboxURL
         let sourceDir = paths.sessionDirectory(workingSession.id)
         let fileName = PDFComposer.fileName(for: workingSession)
         let finalURL = outboxDir.appendingPathComponent(fileName)

Sources/Shotdeck/SettingsView.swift

@@ -82,21 +82,20 @@ struct SettingsView: View {
                             model.chooseOneDriveFolder()
                         }
                     } else {
-                        HStack(spacing: 8) {
+                        // One-line row, same shape as the normal path row: "Not found"
-                            Text("No OneDrive folder found — sign in to OneDrive or choose a folder.")
+                        // where the path would be, Choose… stays live. The explanation
-                                .font(.caption)
+                        // moves to the caption below instead of wrapping this row.
-                                .foregroundStyle(.secondary)
+                        folderValue(path: "Not found") {
-                                .fixedSize(horizontal: false, vertical: true)
+                            model.chooseOneDriveFolder()
-                                .frame(maxWidth: .infinity, alignment: .leading)
-                            Button("Choose…") { model.chooseOneDriveFolder() }
                         }
-                        .frame(minHeight: 22)
                     }
                 }
 
                 GridRow {
                     Text(
-                        "The PDF is saved here and this same folder is watched for the marked-up copy. On the iPad open it from Files > OneDrive."
+                        model.resolvedOneDriveFolder != nil
+                            ? "The PDF is saved here and this same folder is watched for the marked-up copy. On the iPad open it from Files > OneDrive."
+                            : "No OneDrive folder found. Sign in to OneDrive, or choose a folder."
                     )
                     .font(.caption)
                     .foregroundStyle(.secondary)
@@ -249,7 +248,18 @@ extension AppModel: SettingsWindowPresenting {
     /// doesn't exist yet, and re-points the running watcher (folder + recordUncommented)
     /// at the new state. Switching back to AirDrop restores its own stored overrides
     /// untouched, since AirDrop and OneDrive folder settings are stored under separate keys.
+    /// Refuses while a send is in flight (send() snapshots its own folder/transport, but
+    /// switching mid-send is still confusing UX — nothing to gain by allowing it).
+    /// The async reconcile below is generation-guarded: `reconcileGeneration` is bumped
+    /// synchronously before the Task starts, and the Task checks its own snapshot against
+    /// the live value before every mutating step, so rapid toggling (this function or
+    /// chooseOneDriveFolder, in any order) always lets the LAST choice win instead of an
+    /// earlier, superseded call applying its stale folder/flag after a later one already won.
     func chooseTransport(_ value: SendTransport) {
+        guard !isSending else {
+            setStatus("Finish the current send first.")
+            return
+        }
         guard value != transport else { return }
         TransportSettings.setTransport(value)
         setTransport(value)
@@ -261,11 +271,17 @@ extension AppModel: SettingsWindowPresenting {
         }
         setFolderURLs(outbox: folders.outbox, watch: folders.watch)
         setResolvedOneDriveFolder(OneDriveLocator.resolveOneDriveFolder())
+
+        reconcileGeneration += 1
+        let generation = reconcileGeneration
         Task {
+            guard generation == self.reconcileGeneration else { return }
             await watcher.setRecordUncommented(value == .airDrop)
+            guard generation == self.reconcileGeneration else { return }
             do {
                 try await watcher.updateWatchFolder(folders.watch)
             } catch {
+                guard generation == self.reconcileGeneration else { return }
                 setStatus(
                     (error as? ShotdeckError)?.errorDescription ?? "Could not switch the watch folder."
                 )
@@ -273,7 +289,13 @@ extension AppModel: SettingsWindowPresenting {
         }
     }
 
+    /// Refuses while a send is in flight, same reasoning as chooseTransport. See
+    /// chooseTransport's doc comment for the generation-guard mechanism shared here.
     func chooseOneDriveFolder() {
+        guard !isSending else {
+            setStatus("Finish the current send first.")
+            return
+        }
         let start = resolvedOneDriveFolder ?? FileManager.default.homeDirectoryForCurrentUser
         guard let url = chooseDirectory(startingAt: start) else { return }
         TransportSettings.setOneDriveFolder(url)
@@ -281,11 +303,17 @@ extension AppModel: SettingsWindowPresenting {
         setResolvedOneDriveFolder(OneDriveLocator.resolveOneDriveFolder())
         guard transport == .oneDrive else { return }
         setFolderURLs(outbox: url, watch: url)
+
+        reconcileGeneration += 1
+        let generation = reconcileGeneration
         Task {
+            guard generation == self.reconcileGeneration else { return }
             do {
                 try await watcher.updateWatchFolder(url)
+                guard generation == self.reconcileGeneration else { return }
                 setStatus("OneDrive folder set to \(url.lastPathComponent).")
             } catch {
+                guard generation == self.reconcileGeneration else { return }
                 setStatus(
                     (error as? ShotdeckError)?.errorDescription ?? "Could not switch the watch folder."
                 )

Sources/Shotdeck/main.swift

@@ -50,9 +50,18 @@ final class AppDelegate: NSObject, NSApplicationDelegate {
         Task { await model.bootstrap() }
     }
 
-    private static func makeLaunchModel() -> AppModel {
+    /// Builds the model exactly the way the real app launches: paths come from
+    /// `TransportSettings.resolvedAppSupportPaths()` — transport-aware, so the watcher
+    /// this feeds is never seeded with a stale AirDrop folder while OneDrive is the
+    /// persisted transport (that was the BLOCKER this function used to have, when it
+    /// called the AirDrop-only `FolderSettings.resolvedAppSupportPaths()` instead).
+    /// `appSupportRoot` exists only so PickerSelfTest's relaunch-simulation sub-step can
+    /// point this at a temp directory instead of the real
+    /// ~/Library/Application Support/Shotdeck — production always calls this with no
+    /// argument (the real root). Internal, not private, for that same reason.
+    static func makeLaunchModel(appSupportRoot: URL? = nil) -> AppModel {
         do {
-            let paths = try FolderSettings.resolvedAppSupportPaths()
+            let paths = try TransportSettings.resolvedAppSupportPaths(root: appSupportRoot)
             return try makeModel(paths: paths)
         } catch {
             Log.ui.critical(

Sources/ShotdeckCore/Support/AppSupportPaths.swift

@@ -11,12 +11,6 @@ public struct AppSupportPaths: Sendable {
     /// Production paths.
     public static func standard() throws -> AppSupportPaths {
         let fileManager = FileManager.default
-        let appSupportParent = try fileManager.url(
-            for: .applicationSupportDirectory,
-            in: .userDomainMask,
-            appropriateFor: nil,
-            create: true
-        )
         let desktop = try fileManager.url(
             for: .desktopDirectory,
             in: .userDomainMask,
@@ -29,10 +23,25 @@ public struct AppSupportPaths: Sendable {
             appropriateFor: nil,
             create: true
         )
-        let root = appSupportParent.appendingPathComponent("Shotdeck", isDirectory: true)
+        let root = try standardRoot(fileManager: fileManager)
         return try AppSupportPaths(root: root, outbox: desktop, watchFolder: downloads)
     }
 
+    /// The standard `~/Library/Application Support/Shotdeck` root. Shared by
+    /// `standard()`, `FolderSettings.resolvedAppSupportPaths()`, and
+    /// `TransportSettings.resolvedAppSupportPaths()` so all three agree on where the
+    /// root lives — the folder-resolution logic (AirDrop-only vs transport-aware)
+    /// differs between those, the root computation never should.
+    public static func standardRoot(fileManager: FileManager = .default) throws -> URL {
+        let appSupportParent = try fileManager.url(
+            for: .applicationSupportDirectory,
+            in: .userDomainMask,
+            appropriateFor: nil,
+            create: true
+        )
+        return appSupportParent.appendingPathComponent("Shotdeck", isDirectory: true)
+    }
+
     /// Test paths rooted anywhere. Every directory is created if missing.
     public init(root: URL, outbox: URL, watchFolder: URL) throws {
         self.root = root

Sources/ShotdeckCore/Support/FolderSettings.swift

@@ -70,15 +70,7 @@ public enum FolderSettings {
         defaults: UserDefaults = .standard,
         fileManager: FileManager = .default
     ) throws -> AppSupportPaths {
-        let resolvedRoot: URL
+        let resolvedRoot = try root ?? AppSupportPaths.standardRoot(fileManager: fileManager)
-        if let root {
-            resolvedRoot = root
-        } else {
-            let appSupportParent = try fileManager.url(
-                for: .applicationSupportDirectory, in: .userDomainMask,
-                appropriateFor: nil, create: true)
-            resolvedRoot = appSupportParent.appendingPathComponent("Shotdeck", isDirectory: true)
-        }
         let folders = resolve(defaults: defaults, fileManager: fileManager)
         return try AppSupportPaths(root: resolvedRoot, outbox: folders.outbox, watchFolder: folders.watch)
     }

Sources/ShotdeckCore/Support/TransportSettings.swift

@@ -75,6 +75,25 @@ public enum TransportSettings {
             return (folders.outbox, folders.watch, transport)
         }
     }
+
+    /// Builds an `AppSupportPaths` using `root` (defaults to the standard
+    /// `~/Library/Application Support/Shotdeck` when nil) plus whatever
+    /// `effectiveFolders()` returns for outbox/watch. Unlike
+    /// `FolderSettings.resolvedAppSupportPaths()` (AirDrop-only), this is
+    /// transport-aware — it is the ONLY function launch code should use to build its
+    /// paths, so the watcher it feeds is never seeded with a stale AirDrop folder while
+    /// OneDrive is the persisted transport. `root` is exposed purely so tests (and the
+    /// ONEDRIVE-SELFTEST relaunch simulation) can point it at a temporary directory
+    /// instead of the user's real Application Support folder.
+    public static func resolvedAppSupportPaths(
+        root: URL? = nil,
+        defaults: UserDefaults = .standard,
+        fileManager: FileManager = .default
+    ) throws -> AppSupportPaths {
+        let resolvedRoot = try root ?? AppSupportPaths.standardRoot(fileManager: fileManager)
+        let folders = effectiveFolders(defaults: defaults, fileManager: fileManager)
+        return try AppSupportPaths(root: resolvedRoot, outbox: folders.outbox, watchFolder: folders.watch)
+    }
 }
 
 /// Pure path logic for locating a OneDrive sync root under
@@ -142,4 +161,19 @@ public enum OneDriveLocator {
         }
         return defaultRedlineFolder(home: home, fileManager: fileManager)
     }
+
+    /// True when `url` exists as a directory AND is writable by the current process.
+    /// The live check `send(anchor:)` performs before ever composing into a OneDrive
+    /// destination — a directory that exists but has had its permissions revoked (e.g.
+    /// `chmod 500`) must be treated as unavailable, not silently attempted and
+    /// surfaced as a generic PDF-composition failure.
+    public static func isWritableDirectory(
+        at url: URL,
+        fileManager: FileManager = .default
+    ) -> Bool {
+        var isDirectory: ObjCBool = false
+        let exists = fileManager.fileExists(atPath: url.path, isDirectory: &isDirectory)
+        guard exists, isDirectory.boolValue else { return false }
+        return fileManager.isWritableFile(atPath: url.path)
+    }
 }

Tests/ShotdeckCoreTests/ReturnWatcherTests.swift

@@ -282,3 +282,110 @@ func recordUncommentedFalseSkipsUnmarkedThenRecordsAfterInPlaceMarkup() async th
     #expect(commented.count == 1)
     #expect(commented.first?.fileURL.resolvingSymlinksInPath().path == pdfURL.resolvingSymlinksInPath().path)
 }
+
+// MARK: - Launch-paths BLOCKER regression (adversarial review, 20260905)
+//
+// The bug: AppDelegate.makeLaunchModel() built `paths` via the AirDrop-only
+// FolderSettings.resolvedAppSupportPaths(), so ReturnWatcher's internal watchFolder
+// (seeded from paths.watchFolder in its own init) was the AirDrop folder even when
+// OneDrive was the persisted transport, and bootstrap() never reconciled it before
+// starting. Net effect: PDFs went to OneDrive but FSEvents kept watching the stale
+// AirDrop folder for the whole session — marked-up returns were never detected.
+// The fix: launch paths now come from TransportSettings.resolvedAppSupportPaths()
+// (transport-aware), and AppModel.bootstrap() unconditionally reconciles the watcher's
+// folder via updateWatchFolder() before it starts. These two tests characterize the
+// bug (still reproducible via the old AirDrop-only construction) and prove the fix
+// (the real launch-construction path, end to end).
+
+@Test("Launch regression (fix): OneDrive persisted -> transport-aware launch paths -> bootstrap-style reconcile -> a marked PDF is detected")
+func launchStyleConstructionWithOneDriveTransportDetectsAMarkedReturn() async throws {
+    let suite = try makeTransportDefaultsSuite()
+    defer { tearDownTransportSuite(suite) }
+    let oneDriveFolder = try makeTransportTemporaryDirectory(prefix: "shotdeck-launch-onedrive")
+    defer { try? FileManager.default.removeItem(at: oneDriveFolder) }
+    let appSupportRoot = try makeTransportTemporaryDirectory(prefix: "shotdeck-launch-approot")
+    defer { try? FileManager.default.removeItem(at: appSupportRoot) }
+
+    TransportSettings.setTransport(.oneDrive, defaults: suite.defaults)
+    TransportSettings.setOneDriveFolder(oneDriveFolder, defaults: suite.defaults)
+
+    // Exactly what AppDelegate.makeLaunchModel() now does: build launch paths from the
+    // transport-aware resolver — the fix, NOT FolderSettings.resolvedAppSupportPaths(),
+    // which is AirDrop-only and is the root cause the next test characterizes.
+    let paths = try TransportSettings.resolvedAppSupportPaths(
+        root: appSupportRoot, defaults: suite.defaults, fileManager: .default
+    )
+    #expect(paths.outbox.path == oneDriveFolder.path)
+    #expect(paths.watchFolder.path == oneDriveFolder.path)
+
+    let ledger = try ReturnLedger(paths: paths)
+    let watcher = ReturnWatcher(paths: paths, ledger: ledger)
+
+    // What AppModel.bootstrap() now does, unconditionally, before watcher.start():
+    await watcher.setRecordUncommented(false)   // transport == .oneDrive
+    try await watcher.updateWatchFolder(paths.watchFolder)
+
+    let pdfURL = oneDriveFolder.appendingPathComponent("Redline-20260905-100000.pdf")
+    try makePDF(
+        at: pdfURL, pageCount: 1, creator: "Redline",
+        annotations: [(page: 0, annotation: makeAnnotation(
+            .ink, bounds: CGRect(x: 100, y: 100, width: 120, height: 50)
+        ))]
+    )
+
+    let found = try await watcher.scanNow()
+    #expect(found.contains(where: {
+        $0.fileURL.resolvingSymlinksInPath().path == pdfURL.resolvingSymlinksInPath().path && $0.isCommented
+    }))
+
+    let commented = try await ledger.commented()
+    #expect(commented.contains(where: {
+        $0.fileURL.resolvingSymlinksInPath().path == pdfURL.resolvingSymlinksInPath().path
+    }))
+}
+
+@Test("Launch regression (characterizes the bug): AirDrop-only launch paths with no reconcile miss an OneDrive-mode return")
+func airDropOnlyLaunchPathsWithoutReconcileMissesAMarkedOneDriveReturn() async throws {
+    let suite = try makeTransportDefaultsSuite()
+    defer { tearDownTransportSuite(suite) }
+    let oneDriveFolder = try makeTransportTemporaryDirectory(prefix: "shotdeck-buggy-onedrive")
+    defer { try? FileManager.default.removeItem(at: oneDriveFolder) }
+    // A configured AirDrop watch-folder override, isolated to a temp dir — NOT the real
+    // ~/Downloads, which may already hold real marked-up Redline PDFs from actual use
+    // and would make this test's "found.isEmpty" assertion depend on the state of
+    // Ben's real Downloads folder instead of the isolated fixture under test.
+    let staleAirDropFolder = try makeTransportTemporaryDirectory(prefix: "shotdeck-buggy-airdrop-stale")
+    defer { try? FileManager.default.removeItem(at: staleAirDropFolder) }
+    let appSupportRoot = try makeTransportTemporaryDirectory(prefix: "shotdeck-buggy-approot")
+    defer { try? FileManager.default.removeItem(at: appSupportRoot) }
+
+    TransportSettings.setTransport(.oneDrive, defaults: suite.defaults)
+    TransportSettings.setOneDriveFolder(oneDriveFolder, defaults: suite.defaults)
+    FolderSettings.setWatchFolder(staleAirDropFolder, defaults: suite.defaults)
+
+    // The BUG's exact construction: FolderSettings.resolvedAppSupportPaths() ignores
+    // the persisted transport entirely and always resolves the AirDrop folders.
+    let buggyPaths = try FolderSettings.resolvedAppSupportPaths(root: appSupportRoot, defaults: suite.defaults)
+    #expect(buggyPaths.watchFolder.path == staleAirDropFolder.path)
+    #expect(buggyPaths.watchFolder.path != oneDriveFolder.path)
+
+    let ledger = try ReturnLedger(paths: buggyPaths)
+    let watcher = ReturnWatcher(paths: buggyPaths, ledger: ledger)
+    // The old bootstrap(): recordUncommented was set, but there was NO
+    // updateWatchFolder() call before start() to reconcile the folder.
+    await watcher.setRecordUncommented(false)
+
+    let pdfURL = oneDriveFolder.appendingPathComponent("Redline-20260905-100100.pdf")
+    try makePDF(
+        at: pdfURL, pageCount: 1, creator: "Redline",
+        annotations: [(page: 0, annotation: makeAnnotation(
+            .ink, bounds: CGRect(x: 100, y: 100, width: 120, height: 50)
+        ))]
+    )
+
+    // The watcher is still pointed at the stale (configured-AirDrop) watch folder, so
+    // scanning it — NOT the OneDrive folder the PDF actually landed in — finds nothing.
+    // This is the exact BLOCKER the fix above closes.
+    let found = try await watcher.scanNow()
+    #expect(found.isEmpty)
+}

Tests/ShotdeckCoreTests/TransportSettingsTests.swift

@@ -90,6 +90,38 @@ func oneDriveFolderUnavailableErrorDescriptionContainsThePath() throws {
     #expect(description.contains(path))
 }
 
+@Test
+func isWritableDirectoryTrueForAnOrdinaryWritableDirectory() throws {
+    let dir = try makeTransportTemporaryDirectory(prefix: "shotdeck-writable")
+    defer { try? FileManager.default.removeItem(at: dir) }
+    #expect(OneDriveLocator.isWritableDirectory(at: dir))
+}
+
+@Test
+func isWritableDirectoryFalseForAnExistingButUnwritableDirectory() throws {
+    let dir = try makeTransportTemporaryDirectory(prefix: "shotdeck-unwritable")
+    defer {
+        // Restore perms BEFORE removal — an unwritable dir can't otherwise be cleaned up.
+        try? FileManager.default.setAttributes([.posixPermissions: 0o755], ofItemAtPath: dir.path)
+        try? FileManager.default.removeItem(at: dir)
+    }
+    #expect(OneDriveLocator.isWritableDirectory(at: dir))   // sanity check before chmod
+
+    try FileManager.default.setAttributes([.posixPermissions: 0o500], ofItemAtPath: dir.path)
+    #expect(!OneDriveLocator.isWritableDirectory(at: dir))
+}
+
+@Test
+func isWritableDirectoryFalseForAPlainFileAndForANonexistentPath() throws {
+    let dir = try makeTransportTemporaryDirectory(prefix: "shotdeck-writable-check-parent")
+    defer { try? FileManager.default.removeItem(at: dir) }
+    let filePath = dir.appendingPathComponent("plain-file.txt")
+    FileManager.default.createFile(atPath: filePath.path, contents: Data("x".utf8))
+
+    #expect(!OneDriveLocator.isWritableDirectory(at: filePath))
+    #expect(!OneDriveLocator.isWritableDirectory(at: dir.appendingPathComponent("does-not-exist")))
+}
+
 struct TransportDefaultsSuite {
     let name: String
     let defaults: UserDefaults