Add the loss-row banner class and retone degraded paste

02 ratified a warning-tone class for non-failure losses — content that
didn't arrive though nothing failed: a degraded paste, folders skipped
from a Finder drop, their future kin. Loss rows take the one-shot's
dismissable-untimed lifecycle (a loss the user didn't notice is the
harm) and rank below the true failures, above commit and attachment
notices. BannerCenter grows LossBanner, postLoss, and the
skipped-folders phrasing; the degraded-paste notice moves off its
signpost onto the new class, ending its too-quiet ranking.

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

Kanban/LiveStore/BannerCenter.swift

@@ -36,6 +36,34 @@ public struct OneShotBanner: Identifiable, Sendable, Equatable {
     }
 }
 
+/// A loss row: content that didn't arrive though nothing failed (02-architecture.md § The banner
+/// surface, "Loss rows are the warning-tone class for non-failure losses", settled 2026-07-28) — a
+/// degraded paste, folders skipped from a Finder drop, their future kin.
+///
+/// **It takes the one-shot's lifecycle**, deliberately: "a loss the user didn't notice is the harm,
+/// so it never auto-expires" is `OneShotBanner`'s "an error never evaporates unread", read for a row
+/// that reports something incomplete rather than something failed. Carrying its own `id` is the same
+/// consequence: two identical losses a minute apart are two rows, and dismissing one must not take
+/// the other with it.
+///
+/// **It ranks below the true failures and above the ambient notices** — "an action that didn't
+/// happen outranks one that partially did" — which is why it is its own `BannerRow` case rather than
+/// an `OneShotBanner` with a `nil` error or a `InfoSignpost` with a heavier tone: neither of those
+/// vocabularies has a slot at loss's precedence, and bending one to fit would blur the reading that
+/// the class exists to make precise.
+public struct LossBanner: Identifiable, Sendable, Equatable {
+    public let id: UUID
+    public let message: String
+    /// When the loss happened — the sort key for "newest first within a class".
+    public let occurredAt: Date
+
+    public init(id: UUID = UUID(), message: String, occurredAt: Date = Date()) {
+        self.id = id
+        self.message = message
+        self.occurredAt = occurredAt
+    }
+}
+
 /// The standing condition "changes aren't being recorded to history" (02-architecture.md §
 /// Write-failure surfacing, "Auto-commit failures beyond `index.lock` contention").
 ///
@@ -116,7 +144,7 @@ public struct InProgressOperation: Identifiable, Sendable {
 
 /// One row in a window's banner strip.
 ///
-/// The six cases are the whole vocabulary of 02-architecture.md § The banner surface, and they
+/// The seven cases are the whole vocabulary of 02-architecture.md § The banner surface, and they
 /// divide into three lifecycles that the view renders differently and that the ordering rule
 /// treats as classes:
 ///
@@ -124,8 +152,11 @@ public struct InProgressOperation: Identifiable, Sendable {
 ///   ongoing state and carry no dismiss control — "an error never evaporates unread" has a twin,
 ///   "a condition is never dismissed while it is still true". Each leaves when the thing it
 ///   describes stops being true.
-/// - **One-shots dismiss**: `oneShot` and `signpost`. Each reports something that already happened,
-///   so only the user can clear it.
+/// - **One-shots dismiss**: `oneShot`, `loss`, and `signpost`. Each reports something that already
+///   happened, so only the user can clear it. `loss` shares this lifecycle deliberately (settled
+///   2026-07-28) even though it reports no failure: "a loss the user didn't notice is the harm, so
+///   it never auto-expires" is the same reasoning that keeps a one-shot from evaporating unread,
+///   aimed at a row that isn't an error at all.
 /// - **In-progress rows complete or fail**: `inProgress`. Completion clears the row; failure swaps
 ///   it for a one-shot (`BannerCenter.endOperation(_:)` + `post(_:)`).
 ///
@@ -141,6 +172,10 @@ public enum BannerRow: Identifiable, Sendable {
     case reloadBreakage(BoardLoadError)
     /// A write that did not happen. Dismissable, error tone.
     case oneShot(OneShotBanner)
+    /// Content that didn't arrive though nothing failed — a degraded paste, folders skipped from a
+    /// Finder drop, their future kin. Dismissable, warning tone: below the true failures above it,
+    /// above the ambient notices below it (settled 2026-07-28, see `LossBanner`).
+    case loss(LossBanner)
     /// History has stopped advancing. Condition, warning tone — the files are safe, only the undo
     /// trail is degraded, which is a warning rather than an error. (m7's committer drives it.)
     case historySuspended(HistorySuspension)
@@ -156,6 +191,7 @@ public enum BannerRow: Identifiable, Sendable {
         case .readOnlyLock: "read-only-lock"
         case .reloadBreakage: "reload-breakage"
         case let .oneShot(banner): "one-shot:\(banner.id.uuidString)"
+        case let .loss(loss): "loss:\(loss.id.uuidString)"
         case .historySuspended: "history-suspension"
         case let .inProgress(operation): "operation:\(operation.id.uuidString)"
         case let .signpost(signpost): "signpost:\(signpost.id.uuidString)"
@@ -165,7 +201,7 @@ public enum BannerRow: Identifiable, Sendable {
     public var tone: BannerTone {
         switch self {
         case .readOnlyLock, .reloadBreakage, .oneShot: .error
-        case .historySuspended: .warning
+        case .historySuspended, .loss: .warning
         case .inProgress, .signpost: .info
         }
     }
@@ -184,18 +220,20 @@ public enum BannerRow: Identifiable, Sendable {
         case let .readOnlyLock(reason): BannerCenter.headline(for: reason)
         case let .reloadBreakage(error): BannerCenter.headline(for: error)
         case let .oneShot(banner): BannerCenter.headline(for: banner.error)
+        case let .loss(loss): loss.message
         case let .historySuspended(suspension): BannerCenter.headline(for: suspension)
         case let .inProgress(operation): operation.label
         case let .signpost(signpost): signpost.message
         }
     }
 
-    /// Only the rows reporting something that already happened carry a dismiss control — one-shot
-    /// failures and signposts. Conditions stand until they heal; in-progress rows complete, fail, or
-    /// are cancelled — neither is something a user can wave away.
+    /// Only the rows reporting something that already happened carry a dismiss control —
+    /// one-shot failures, loss rows, and signposts. Conditions stand until they heal; in-progress
+    /// rows complete, fail, or are cancelled — neither is something a user can wave away.
     public var dismissID: UUID? {
         switch self {
         case let .oneShot(banner): banner.id
+        case let .loss(loss): loss.id
         case let .signpost(signpost): signpost.id
         case .readOnlyLock, .reloadBreakage, .historySuspended, .inProgress: nil
         }
@@ -209,12 +247,12 @@ public enum BannerRow: Identifiable, Sendable {
 ///
 /// ### What lives here and what does not
 ///
-/// A center holds the state nothing else does: dismissable one-shot write failures, the history
-/// suspension, in-progress operations, and passive signposts. It deliberately does **not** hold the
-/// read-only lock or the reload breakage — those are `BoardStore`'s truths, and copying them here
-/// would create a second place for them to be stale. `BoardStore.bannerRows` composes both halves
-/// through `rows(lock:breakage:oneShots:suspension:operations:signposts:)`, which is a *pure
-/// function* precisely so the precedence rule can be tested without a store, a window, or a
+/// A center holds the state nothing else does: dismissable one-shot write failures, loss rows, the
+/// history suspension, in-progress operations, and passive signposts. It deliberately does **not**
+/// hold the read-only lock or the reload breakage — those are `BoardStore`'s truths, and copying
+/// them here would create a second place for them to be stale. `BoardStore.bannerRows` composes both
+/// halves through `rows(lock:breakage:oneShots:losses:suspension:operations:signposts:)`, which is a
+/// *pure function* precisely so the precedence rule can be tested without a store, a window, or a
 /// filesystem.
 ///
 /// ### Phrasing lives here too
@@ -243,6 +281,11 @@ public final class BannerCenter {
     /// turn — still order deterministically.
     public private(set) var oneShots: [OneShotBanner] = []
 
+    /// Newest first, like `oneShots` — content that didn't arrive though nothing failed,
+    /// dismissable and untimed for the same reason a one-shot failure is (settled 2026-07-28, see
+    /// `LossBanner`).
+    public private(set) var losses: [LossBanner] = []
+
     /// The standing "history isn't advancing" condition, or `nil` when commits are landing.
     public private(set) var historySuspension: HistorySuspension?
 
@@ -265,6 +308,12 @@ public final class BannerCenter {
         oneShots.insert(OneShotBanner(error: error), at: 0)
     }
 
+    /// Posts a loss row — content that didn't arrive though nothing failed (settled 2026-07-28, see
+    /// `LossBanner`). Newest first, like the one-shots it shares a lifecycle with.
+    public func postLoss(_ message: String) {
+        losses.insert(LossBanner(message: message), at: 0)
+    }
+
     /// Posts a passive notice — m6's remote-change signpost and whatever joins it. Newest first,
     /// like the one-shots it shares a lifecycle with.
     public func postSignpost(_ message: String) {
@@ -292,34 +341,52 @@ public final class BannerCenter {
     /// intact, attachments absent — and this is the row that says so. "A degraded paste is loud,
     /// never silent … the user never discovers an empty `attachments/` later."
     ///
-    /// **A signpost, not a `oneShot`**, and the choice is the vocabulary's rather than a compromise:
-    /// 02-architecture.md's `oneShot` is *a write that did not happen*, carrying a `BoardWriteError`,
-    /// and nothing here failed — the items landed, whole but for files that were never on the
-    /// pasteboard's side of the transfer. A signpost is the other member of the same lifecycle class
-    /// ("one-shots dismiss"): it reports something that already happened, it has no timeout, and only
-    /// the user clears it, which is the whole of "never evaporates unread". What it costs is
-    /// precedence — a signpost ranks last and may collapse behind "+N more" — which is the one place
-    /// this row reads quieter than 04's "loud" deserves. See the report's design-gap note.
+    /// **A loss row, not a `oneShot` and not a signpost** — the vocabulary's answer rather than a
+    /// compromise (settled 2026-07-28). 02-architecture.md's `oneShot` is *a write that did not
+    /// happen*, carrying a `BoardWriteError`, and nothing here failed — the items landed, whole but
+    /// for files that were never on the pasteboard's side of the transfer. This row first shipped as
+    /// a signpost, the vocabulary's other one-shot-lifecycle member at the time, and it read quieter
+    /// than 04's "loud" deserved: a signpost ranks last and may collapse behind "+N more", exactly
+    /// where a board already showing real trouble would bury it. The loss class exists to close that
+    /// gap — content that didn't arrive though nothing failed ranks below the true failures and
+    /// above the ambient notices, keeping the signpost's dismissable, untimed lifecycle without
+    /// inheriting its bottom-of-the-strip precedence.
     ///
     /// An empty list posts nothing: a fallback that lost no attachments lost nothing at all, and a
     /// banner announcing that would be noise.
     public func postDegradedPaste(_ losses: [AttachmentLoss]) {
         guard let message = Self.degradedPasteMessage(for: losses) else { return }
-        postSignpost(message)
+        postLoss(message)
     }
 
-    /// Removes a dismissable row: a one-shot failure or a signpost. **An id that names an
-    /// in-progress operation is ignored** rather than ending it, because "dismiss" and "cancel" are
-    /// different promises and a row that offers one must never quietly do the other.
+    /// Posts the skipped-folders loss row for a Finder drop that imported its files but refused its
+    /// folders (04-interactions.md ▸ Selection, drag & drop, "Folders are refused at hover"): "a
+    /// mixed drag proposes for its files only, and the drop imports the files while a one-shot
+    /// banner names the skipped folders" — now a loss row, for the same reason the degraded paste is
+    /// one (settled 2026-07-28): folders that never arrived are a non-failure loss, not a write
+    /// failure.
+    ///
+    /// A drop with no skipped folders posts nothing — nothing was lost, so there is nothing to say.
+    public func postSkippedFolders(count: Int) {
+        guard count > 0 else { return }
+        postLoss(Self.skippedFoldersMessage(count: count))
+    }
+
+    /// Removes a dismissable row: a one-shot failure, a loss row, or a signpost. **An id that names
+    /// an in-progress operation is ignored** rather than ending it, because "dismiss" and "cancel"
+    /// are different promises and a row that offers one must never quietly do the other.
     public func dismiss(_ id: UUID) {
         oneShots.removeAll { $0.id == id }
+        losses.removeAll { $0.id == id }
         signposts.removeAll { $0.id == id }
     }
 
-    /// Removes every dismissable row — one-shots and signposts alike. The strip's own "clear all"
-    /// affordance later; today it is what a window uses when it re-homes its rows elsewhere (m6).
+    /// Removes every dismissable row — one-shots, losses, and signposts alike. The strip's own
+    /// "clear all" affordance later; today it is what a window uses when it re-homes its rows
+    /// elsewhere (m6).
     public func dismissAllDismissableRows() {
         oneShots.removeAll()
+        losses.removeAll()
         signposts.removeAll()
     }
 
@@ -371,8 +438,8 @@ public final class BannerCenter {
     /// function** (02 § The banner surface, "Concurrent conditions stack").
     ///
     /// The precedence, settled: **in-progress rows (pinned)** > read-only lock > reload breakage >
-    /// one-shot write failures > commit and attachment failures > **passive info rows**. Three
-    /// readings of it are worth stating because the code depends on them:
+    /// one-shot write failures > **loss rows** > commit and attachment failures > **passive info
+    /// rows**. Four readings of it are worth stating because the code depends on them:
     ///
     /// - **The two info classes sit at opposite ends of the strip.** An in-progress row is pinned
     ///   above everything: it is the only explanation the strip offers for a bracket's write lock
@@ -380,6 +447,13 @@ public final class BannerCenter {
     ///   — "a spinner may never hide behind '+N more'". A passive signpost ranks last and may
     ///   collapse: calm by design, nothing gated on seeing it instantly. Same tone, opposite
     ///   urgency.
+    /// - **Loss rows slot between the true failures and the ambient notices** (settled 2026-07-28):
+    ///   "an action that didn't happen outranks one that partially did" is why a loss ranks below
+    ///   every one-shot write failure, while "content that didn't arrive though nothing failed" is
+    ///   still more consequential than a condition or a signpost that only reports ambient state —
+    ///   so a loss also ranks above `historySuspended` and the attachment one-shots that follow it.
+    ///   Concretely: non-attachment one-shots, then loss rows, then the commit-and-attachment class,
+    ///   then signposts.
     /// - **An attachment failure is a one-shot**, not a separate kind — its `WriteOperation` is
     ///   `.importAttachment`. It ranks in the commit-failure class rather than with its fellow
     ///   one-shots, so a fresh failed import sits below an older failed move. That is the design's
@@ -393,11 +467,13 @@ public final class BannerCenter {
     ///   so they are ordered by kind, and recency orders only the one-shots among themselves.
     ///
     /// `signposts` carries a default because its producer is m6's card window and nothing posts one
-    /// today; every other class has a live producer and is spelled out at every call site.
+    /// today; every other class has a live producer and is spelled out at every call site — `losses`
+    /// included, since a degraded paste already posts one (`postDegradedPaste`).
     public nonisolated static func rows(
         lock: ReadOnlyLockReason?,
         breakage: BoardLoadError?,
         oneShots: [OneShotBanner],
+        losses: [LossBanner],
         suspension: HistorySuspension?,
         operations: [InProgressOperation],
         signposts: [InfoSignpost] = []
@@ -416,6 +492,8 @@ public final class BannerCenter {
         let ordered = newestFirst(oneShots)
         rows.append(contentsOf: ordered.lazy.filter { !$0.isAttachmentImport }.map(BannerRow.oneShot))
 
+        rows.append(contentsOf: newestFirst(losses).map(BannerRow.loss))
+
         if let suspension {
             rows.append(.historySuspended(suspension))
         }
@@ -440,6 +518,20 @@ public final class BannerCenter {
             .map(\.element)
     }
 
+    /// The same stable newest-first ordering as the overload above, for loss rows — the two classes
+    /// share a lifecycle, and `postLoss` already maintains newest-first on insertion the way
+    /// `post(_:)` does.
+    private nonisolated static func newestFirst(_ losses: [LossBanner]) -> [LossBanner] {
+        losses
+            .enumerated()
+            .sorted { lhs, rhs in
+                lhs.element.occurredAt == rhs.element.occurredAt
+                    ? lhs.offset < rhs.offset
+                    : lhs.element.occurredAt > rhs.element.occurredAt
+            }
+            .map(\.element)
+    }
+
     // MARK: - Phrasing
 
     /// The user-facing line for a failed write: what the app could not do, then why.
@@ -575,6 +667,18 @@ public final class BannerCenter {
         return "Pasted \(subject) without \(tail)"
     }
 
+    /// The skipped-folders line — 04-interactions.md's own example, "Folders can't be attached — 2
+    /// skipped", generalized over the count. `postSkippedFolders` never calls this at `count == 0`,
+    /// so every real call already has something to report.
+    ///
+    /// **Singular stays "Folders can't be attached — 1 skipped"** rather than recasting the leading
+    /// clause to "A folder can't be attached": the claim is always about the drag as a whole — *its*
+    /// folders didn't make it in — and only the trailing count varies, which is one sentence shape
+    /// for every count instead of two that would have to be kept in agreement with each other.
+    public nonisolated static func skippedFoldersMessage(count: Int) -> String {
+        "Folders can't be attached — \(count) skipped"
+    }
+
     /// The suspended-history line. It names the *consequence* the user cares about — undo and the
     /// flush-before-overwrite guarantee are degraded — rather than the git mechanics, and carries
     /// the diagnosis as its tail.

Kanban/LiveStore/BoardStore.swift

@@ -196,9 +196,9 @@ public final class BoardStore {
     /// failures, and re-homes those rows here when it closes; injecting a shared center would
     /// erase precisely that distinction.
     ///
-    /// It holds only what nothing else does — one-shot write failures, the history suspension,
-    /// in-progress operations, passive signposts. The lock and the reload breakage stay this
-    /// store's own state and are composed in at render time by `bannerRows`.
+    /// It holds only what nothing else does — one-shot write failures, loss rows, the history
+    /// suspension, in-progress operations, passive signposts. The lock and the reload breakage stay
+    /// this store's own state and are composed in at render time by `bannerRows`.
     public let banners = BannerCenter()
 
     /// The rows the board window's strip renders, in precedence order.
@@ -211,6 +211,7 @@ public final class BoardStore {
             lock: readOnlyLock,
             breakage: reloadFailure,
             oneShots: banners.oneShots,
+            losses: banners.losses,
             suspension: banners.historySuspension,
             operations: banners.operations,
             signposts: banners.signposts