diff --git a/OutlineKit/Sources/OutlineKit/LiveOutlineAPIClient.swift b/OutlineKit/Sources/OutlineKit/LiveOutlineAPIClient.swift
index 437b7b5..18090e6 100644
--- a/OutlineKit/Sources/OutlineKit/LiveOutlineAPIClient.swift
+++ b/OutlineKit/Sources/OutlineKit/LiveOutlineAPIClient.swift
@@ -299,15 +299,15 @@ private struct DuplicateDocumentResponse: Decodable {
     let documents: [OutlineDocument]
 }
 
-private struct ListStarsResponse: Decodable {
-    let stars: [OutlineStar]
-}
-
 private struct PinsListPayload: Decodable {
     let pins: [OutlinePin]
     let documents: [OutlineDocument]
 }
 
+private struct ListStarsResponse: Decodable {
+    let stars: [OutlineStar]
+}
+
 private struct StarIDParams: Encodable {
     let id: String
 }
diff --git a/Outpost/Features/Collections/CollectionDocumentsOutline.swift b/Outpost/Features/Collections/CollectionDocumentsOutline.swift
index 1013033..593fe2f 100644
--- a/Outpost/Features/Collections/CollectionDocumentsOutline.swift
+++ b/Outpost/Features/Collections/CollectionDocumentsOutline.swift
@@ -9,6 +9,7 @@ import OutlineKit
 /// client-side rather than `collections.documents`.
 struct CollectionDocumentsOutline: View {
     let apiClient: OutlineAPIClient
+    let collection: OutlineCollection
     @State private var viewModel: DocumentsViewModel
     let sortOption: SidebarSortOption
     let refreshToken: Int
@@ -24,6 +25,11 @@ struct CollectionDocumentsOutline: View {
     /// toolbar render the real hierarchy instead of just the leaf title.
     let onSelectDocument: ([OutlineDocument]) -> Void
 
+    /// Loaded once per collection (`pins.list` is collection-scoped) rather
+    /// than per-row — a per-row `pins.list`/lookup would be an N+1 call for
+    /// every document in the tree.
+    @State private var pinsByDocumentID: [String: OutlinePin] = [:]
+
     private var tree: [DocumentNode] {
         buildDocumentTree(from: viewModel.documents, sortedBy: sortOption)
     }
@@ -38,6 +44,7 @@ struct CollectionDocumentsOutline: View {
         onSelectDocument: @escaping ([OutlineDocument]) -> Void
     ) {
         self.apiClient = apiClient
+        self.collection = collection
         _viewModel = State(initialValue: DocumentsViewModel(apiClient: apiClient, collection: collection))
         self.sortOption = sortOption
         self.refreshToken = refreshToken
@@ -65,8 +72,10 @@ struct CollectionDocumentsOutline: View {
                         depth: 0,
                         ancestors: [],
                         selectedDocumentID: selectedDocumentID,
+                        pinsByDocumentID: pinsByDocumentID,
                         onSelectDocument: onSelectDocument,
-                        onDocumentsChanged: { await viewModel.load() }
+                        onDocumentsChanged: { await viewModel.load() },
+                        onPinsChanged: { await loadPins() }
                     )
                 }
             }
@@ -74,7 +83,15 @@ struct CollectionDocumentsOutline: View {
         // Combined into one identity rather than two separate `.task(id:)`
         // modifiers — each of those fires once unconditionally on first
         // appear, so two of them would double the initial load.
-        .task(id: "\(refreshToken)-\(externalRefreshToken)") { await viewModel.load() }
+        .task(id: "\(refreshToken)-\(externalRefreshToken)") {
+            await viewModel.load()
+            await loadPins()
+        }
+    }
+
+    private func loadPins() async {
+        guard let pins = try? await apiClient.listPins(ListPinsRequest(collectionId: collection.id)) else { return }
+        pinsByDocumentID = Dictionary(uniqueKeysWithValues: pins.map { ($0.documentId, $0) })
     }
 }
 
@@ -93,8 +110,10 @@ private struct DocumentNodeRow: View {
     /// Chain from root down to (not including) this node.
     let ancestors: [OutlineDocument]
     let selectedDocumentID: String?
+    let pinsByDocumentID: [String: OutlinePin]
     let onSelectDocument: ([OutlineDocument]) -> Void
     let onDocumentsChanged: () async -> Void
+    let onPinsChanged: () async -> Void
 
     @State private var isExpanded = false
 
@@ -185,8 +204,10 @@ private struct DocumentNodeRow: View {
                         depth: depth + 1,
                         ancestors: ancestors + [node.document],
                         selectedDocumentID: selectedDocumentID,
+                        pinsByDocumentID: pinsByDocumentID,
                         onSelectDocument: onSelectDocument,
-                        onDocumentsChanged: onDocumentsChanged
+                        onDocumentsChanged: onDocumentsChanged,
+                        onPinsChanged: onPinsChanged
                     )
                 }
             }
@@ -277,7 +298,11 @@ private struct DocumentNodeRow: View {
         Button(starStore.isStarred(documentId: node.document.id) ? "Unstar" : "Star") {
             Task { await star() }
         }
-        // No `subscriptions.*` endpoint in the API — nothing to back this with.
+        // subscriptions.* does exist and works (confirmed against a live
+        // server via the reader's menu) — not shown here because
+        // subscriptions.list is per-document, so reflecting accurate
+        // per-row state for every document in the tree would mean an N+1
+        // call storm. Use the reader's ⋯ menu instead.
         Button("Unsubscribe") {}
             .disabled(true)
 
@@ -323,12 +348,11 @@ private struct DocumentNodeRow: View {
         Button("New Document") {
             isShowingNewDocumentSheet = true
         }
-        // `pins.*` is real and works (see `OutlinePin`), but "Pin to
-        // Collection" (non-nil `collectionId`) is distinct from the reader
-        // toolbar's "Pin to Home" and needs its own per-row state/N+1
-        // consideration for a whole tree — not wired here yet.
-        Button("Pin") {}
-            .disabled(true)
+        // Scoped to this collection (`collection.id`) — "Pin to Collection",
+        // distinct from the reader toolbar's "Pin to Home" (collectionId: nil).
+        Button(pinsByDocumentID[node.document.id] != nil ? "Unpin from Collection" : "Pin to Collection") {
+            Task { await togglePin() }
+        }
 
         Divider()
 
@@ -372,6 +396,19 @@ private struct DocumentNodeRow: View {
         }
     }
 
+    private func togglePin() async {
+        do {
+            if let pin = pinsByDocumentID[node.document.id] {
+                try await apiClient.deletePin(id: pin.id)
+            } else {
+                _ = try await apiClient.createPin(CreatePinRequest(documentId: node.document.id, collectionId: node.document.collectionId))
+            }
+            await onPinsChanged()
+        } catch {
+            actionErrorMessage = outlineErrorMessage(error, fallback: "Couldn't update pin state.")
+        }
+    }
+
     private func rename() async {
         do {
             _ = try await apiClient.updateDocument(UpdateDocumentRequest(id: node.document.id, title: renameText))