Rewrite selected text with AI (tones, local or your own cloud model)

AGENTS.md

@@ -198,7 +198,9 @@ The Swift generation loop owns the maximum output-token budget.
   reads as overwriting them. Change those pure helpers and their tests rather than nudging offsets
   in the controller.
 - `SuggestionOverlayPresenter` decides whether a suggestion should be shown or hidden.
-- `ActivationIndicatorController` owns the optional caret/field-edge indicator.
+- `ActivationIndicatorController` owns the optional caret/field-edge indicator. Selection rewrite
+  borrows it as its wand button while text is selected (`showRewrite` / `endRewrite`);
+  `SelectionRewriteCoordinator` owns that flow, its popup and its Replace checks.
 - `FocusDebugOverlayController` is for developer visibility and should stay gated behind debug
   options, not normal user settings.
 - Settings panes (under `Cotabby/UI/Settings/Panes/`) and onboarding views should remain

ARCHITECTURE.md

@@ -498,6 +498,26 @@ the single input-capture slot between:
 Both use pure trigger state machines, stay pinned to one supported focus sequence, and cancel on
 focus change or incompatible input. They do not call a language model.
 
+Selection rewrite is a sibling feature with its own state machine,
+[SelectionRewriteCoordinator.swift](Cotabby/App/Coordinators/Rewrite/SelectionRewriteCoordinator.swift)
+(hidden → button → popup → generating → preview). Focus snapshots carry the selected text and its
+range in the host's value (`selectedText`, `hostSelection`). A stable selection that
+[SelectionRewriteEligibility.swift](Cotabby/Support/Rewrite/SelectionRewriteEligibility.swift) accepts
+(two words or more, not secure, not a terminal, Cotabby on for the app) turns the field-edge icon into a
+wand (`ActivationIndicatorController.showRewrite`) and arms ⌃⌥R through a `TemporaryKeyTap` that exists only
+while that selection is armed; the "Rewrite Selected Text" switch in Settings → Rewrite turns all of it off. The popup is
+a non-activating panel that takes the keyboard while open, so Return can never reach a chat app.
+[RewriteEngine.swift](Cotabby/Services/Rewrite/RewriteEngine.swift) runs one rewrite on the provider
+chosen in Settings → Rewrite: `LocalRewriteProvider` (Apple Intelligence, else the selected llama base
+model with an example-style prompt that stops at the next `Draft:`), or `APIRewriteProvider` (Claude via
+Anthropic's Messages API, other services via OpenAI-compatible chat completions, each service's key in
+its own Keychain item). [RewritePromptBuilder.swift](Cotabby/Support/Rewrite/RewritePromptBuilder.swift)
+names the draft's language (`RewriteLanguageDetector`), `RewriteOutputCleaner` strips prefaces, fences
+and quotes and rejects runaway output, and `RewriteSpecificsCheck` flags numbers and names the user did
+not write, which turns plain Replace off. Replace pastes over the selection only after
+[SelectionReplaceValidator.swift](Cotabby/Support/Rewrite/SelectionReplaceValidator.swift) confirms the
+same field, text and range, then reads the field back; anything else goes to the clipboard with a notice.
+
 [SettingsCoordinator.swift](Cotabby/App/Coordinators/SettingsCoordinator.swift) and
 [WelcomeCoordinator.swift](Cotabby/App/Coordinators/WelcomeCoordinator.swift) own app-lifetime AppKit
 windows hosting SwiftUI content. Settings and onboarding observe the shared graph. Hiding the menu bar
@@ -583,6 +603,7 @@ policies, prompt utilities, normalization, and layout logic should receive focus
 | Clipboard context is irrelevant | ClipboardRelevanceFilter, ClipboardContentDistiller |
 | Screenshot context is stale/noisy | VisualContextCoordinator, OCRTextHygiene |
 | Emoji or macro conflicts with suggestions | InlineCommandCoordinator, feature trigger machine |
+| Rewrite wand missing, popup misplaced, or Replace copies instead | SelectionRewriteCoordinator, SelectionRewriteEligibility, SelectionReplaceValidator |
 | Permission loop or lost grant | PermissionManager, PermissionGuidanceController, app identity |
 | Settings/onboarding window issue | SettingsCoordinator, WelcomeCoordinator |
 | Settings persistence or domain mismatch | SuggestionSettingsModel, SuggestionSettingsData, SuggestionSettingsStore |

Cotabby/App/Coordinators/SettingsCoordinator.swift

@@ -26,6 +26,9 @@ final class SettingsCoordinator: NSObject, NSWindowDelegate {
     private let onShowWelcome: () -> Void
     private let clearEmojiHistory: () -> Void
     private let typingHistoryStore: TypingHistoryStore
+    private let rewritePreferences: RewritePreferencesStore
+    private let rewriteCredentials: RewriteCredentialVault
+    private let rewriteModelList: RewriteModelListService
 
     private var settingsWindowController: NSWindowController?
 
@@ -51,7 +54,10 @@ final class SettingsCoordinator: NSObject, NSWindowDelegate {
         systemMetricsStore: SystemMetricsStore,
         onShowWelcome: @escaping () -> Void,
         clearEmojiHistory: @escaping () -> Void,
-        typingHistoryStore: TypingHistoryStore
+        typingHistoryStore: TypingHistoryStore,
+        rewritePreferences: RewritePreferencesStore,
+        rewriteCredentials: RewriteCredentialVault,
+        rewriteModelList: RewriteModelListService
     ) {
         self.appUpdateManager = appUpdateManager
         self.permissionManager = permissionManager
@@ -68,6 +74,9 @@ final class SettingsCoordinator: NSObject, NSWindowDelegate {
         self.onShowWelcome = onShowWelcome
         self.clearEmojiHistory = clearEmojiHistory
         self.typingHistoryStore = typingHistoryStore
+        self.rewritePreferences = rewritePreferences
+        self.rewriteCredentials = rewriteCredentials
+        self.rewriteModelList = rewriteModelList
     }
 
     /// Shows the settings window, reusing the existing instance if it is already open.
@@ -98,6 +107,9 @@ final class SettingsCoordinator: NSObject, NSWindowDelegate {
                     onShowWelcome: onShowWelcome,
                     clearEmojiHistory: clearEmojiHistory,
                     typingHistoryStore: typingHistoryStore,
+                    rewritePreferences: rewritePreferences,
+                    rewriteCredentials: rewriteCredentials,
+                    rewriteModelList: rewriteModelList,
                     onQuit: { NSApplication.shared.terminate(nil) }
                 )
             )

Cotabby/App/Core/AppDelegate.swift

@@ -94,6 +94,13 @@ final class AppDelegate: NSObject, NSApplicationDelegate {
             }
             .store(in: &cancellables)
 
+        // Selection rewrite borrows the field-edge icon while text is selected; when it gives the icon
+        // back, show the normal icon for the current focus at once.
+        activationIndicatorController.onRewriteEnded = { [weak self] in
+            guard let self else { return }
+            self.updateActivationIndicator(for: self.focusModel.snapshot)
+        }
+
         focusModel.$snapshot
             .sink { [weak self] snapshot in
                 self?.updateActivationIndicator(for: snapshot)
@@ -169,6 +176,7 @@ final class AppDelegate: NSObject, NSApplicationDelegate {
         appUpdateManager.start()
         suggestionCoordinator.start()
         inlineCommandCoordinator.start()
+        environment.selectionRewriteCoordinator.start()
         welcomeCoordinator.presentIfNeeded()
         welcomeCoordinator.presentPermissionReminderIfNeeded()
         didStartServices = true
@@ -253,6 +261,7 @@ final class AppDelegate: NSObject, NSApplicationDelegate {
         // Write the field being typed in now; the debounced background save may not have run yet.
         environment.typingHistoryStore.flush()
         inlineCommandCoordinator.stop()
+        environment.selectionRewriteCoordinator.stop()
         inputMonitor.stop()
         focusModel.stop()
 

Cotabby/App/Core/CotabbyAppEnvironment.swift

@@ -41,6 +41,8 @@ final class CotabbyAppEnvironment {
     let performanceMetricsStore: PerformanceMetricsStore
     let qualityMetricsStore: SuggestionQualityMetricsStore
     let typingHistoryStore: TypingHistoryStore
+    /// Selection rewrite: the popup flow, started and stopped by `AppDelegate`.
+    let selectionRewriteCoordinator: SelectionRewriteCoordinator
     let settingsCoordinator: SettingsCoordinator
     let activationIndicatorController: ActivationIndicatorController
     let focusDebugOverlayController: FocusDebugOverlayController?
@@ -243,6 +245,55 @@ final class CotabbyAppEnvironment {
         // "Clear History" control can reach it, and before the picker which reads and writes it.
         let emojiUsageStore = EmojiUsageStore()
 
+        // Selection rewrite: its own preferences and Keychain items, a local and a cloud provider,
+        // and the shared inserter and llama runtime. Built once here: the same store and credential
+        // instances feed the Settings pane and the engine, so a saved change applies at once.
+        let rewritePreferences = RewritePreferencesStore()
+        // One Keychain item per cloud service, so switching services keeps every key.
+        let rewriteCredentials = RewriteCredentialVault()
+        let anthropicClient = AnthropicMessagesClient()
+        let rewriteModelList = RewriteModelListService(client: openAICompatibleClient, anthropic: anthropicClient)
+        let rewriteEngine = RewriteEngine(
+            local: LocalRewriteProvider(
+                runtimeManager: runtimeManager,
+                hasLocalModel: { [weak runtimeModel] in runtimeModel?.selectedModelFilename != nil },
+                availability: foundationModelAvailabilityService
+            ),
+            api: APIRewriteProvider(
+                client: openAICompatibleClient,
+                anthropic: anthropicClient,
+                preferences: { [weak rewritePreferences] in rewritePreferences?.preferences ?? .defaults },
+                credentials: { [weak rewriteCredentials] service in
+                    rewriteCredentials?.store(for: service) ?? InMemoryOpenAICompatibleCredentialStore()
+                }
+            ),
+            preferences: { [weak rewritePreferences] in rewritePreferences?.preferences ?? .defaults }
+        )
+        let selectionRewriteCoordinator = SelectionRewriteCoordinator(
+            snapshots: focusModel.$snapshot.eraseToAnyPublisher(),
+            // `@Published` emits the new value before the store's property changes, so the coordinator
+            // acts on the emitted value; `dropFirst` skips the replayed current one.
+            enabledChanges: rewritePreferences.$preferences.map(\.isEnabled).removeDuplicates().dropFirst().eraseToAnyPublisher(),
+            currentSnapshot: { [weak focusModel] in focusModel?.snapshot ?? .inactive },
+            refreshFocus: { [weak focusModel] in focusModel?.refreshNow() },
+            presenter: SelectionRewritePanelController(indicator: activationIndicatorController),
+            output: LiveSelectionRewriteTextOutput(inserter: suggestionInserter),
+            engine: rewriteEngine,
+            preferences: { [weak rewritePreferences] in rewritePreferences?.preferences ?? .defaults },
+            isAppAllowed: { [weak suggestionSettings, weak lowPowerModeMonitor] input in
+                SelectionRewriteEligibility.isAppAllowed(
+                    for: input,
+                    settings: suggestionSettings?.snapshot,
+                    isLowPowerModeEnabled: lowPowerModeMonitor?.isLowPowerModeEnabled ?? false,
+                    disabledDomains: PerDomainDisableSettings.disabledDomains()
+                )
+            },
+            hotkey: TemporaryKeyTap(suppressionController: suppressionController),
+            keyTap: TemporaryKeyTap(suppressionController: suppressionController),
+            writingLanguages: { [weak suggestionSettings] in suggestionSettings?.responseLanguages ?? [] },
+            setFixesMistakes: { [weak rewritePreferences] in rewritePreferences?.setFixesMistakes($0) }
+        )
+
         let settingsCoordinator = SettingsCoordinator(
             appUpdateManager: appUpdateManager,
             permissionManager: permissionManager,
@@ -260,7 +311,10 @@ final class CotabbyAppEnvironment {
                 welcomeCoordinator?.showWelcome()
             },
             clearEmojiHistory: { emojiUsageStore.clear() },
-            typingHistoryStore: typingHistoryStore
+            typingHistoryStore: typingHistoryStore,
+            rewritePreferences: rewritePreferences,
+            rewriteCredentials: rewriteCredentials,
+            rewriteModelList: rewriteModelList
         )
 
         let interactionState = SuggestionInteractionState()
@@ -367,6 +421,7 @@ final class CotabbyAppEnvironment {
         self.performanceMetricsStore = performanceMetricsStore
         self.qualityMetricsStore = qualityMetricsStore
         self.typingHistoryStore = typingHistoryStore
+        self.selectionRewriteCoordinator = selectionRewriteCoordinator
         self.settingsCoordinator = settingsCoordinator
         self.activationIndicatorController = activationIndicatorController
         self.focusDebugOverlayController = CotabbyDebugOptions.areOverlaysAvailable

Cotabby/Models/Focus/FocusModels.swift

@@ -360,6 +360,13 @@ nonisolated struct FocusedInputSnapshot: Equatable {
     let trailingText: String
     let selection: NSRange
     let isSecure: Bool
+    /// The text the user has selected, cut from the same bounded window as `precedingText` and
+    /// `trailingText`; empty when the selection is a caret. Selection rewrite reads it.
+    let selectedText: String
+    /// The selection in the host's full value, for restoring it through `kAXSelectedTextRangeAttribute`;
+    /// nil when the host only exposes window-relative text markers (Chromium contenteditables), where
+    /// a rewrite then copies instead of restoring.
+    let hostSelection: NSRange?
 
     /// True when the resolved field is an xterm.js integrated-terminal surface (VS Code / Cursor /
     /// Windsurf terminal, or a browser-hosted web terminal). Set by `FocusSnapshotResolver` from the
@@ -446,7 +453,9 @@ nonisolated struct FocusedInputSnapshot: Equatable {
         fieldPlaceholder: String? = nil,
         hostTextMetrics: HostTextMetrics? = nil,
         elementFrameRect: CGRect? = nil,
-        hostMarkedTextRange: NSRange? = nil
+        hostMarkedTextRange: NSRange? = nil,
+        selectedText: String = "",
+        hostSelection: NSRange? = nil
     ) {
         self.applicationName = applicationName
         self.bundleIdentifier = bundleIdentifier
@@ -474,6 +483,8 @@ nonisolated struct FocusedInputSnapshot: Equatable {
         self.hostTextMetrics = hostTextMetrics
         self.elementFrameRect = elementFrameRect
         self.hostMarkedTextRange = hostMarkedTextRange
+        self.selectedText = selectedText
+        self.hostSelection = hostSelection
     }
 
     var identity: FocusedInputIdentity {