feat(translation-polish): dual-engine translation UX + provider picker filter + topbar cleanup

- Add LLMProvider.isUserSelectable (default true) and filter
  ProviderPickerSection on it; next pass can hide non-user presets
  (e.g. a future DeepSeek key-preset) without changing call sites.
- KeyboardRootView: hide TranslationChip when off (matches user's
  mental model of an opt-in feature), drop the 'warming' branch
  (Qwen3 download UX was removed with the backend in v0.2.0), unify
  chip pill height to minHeight 28 + vertical 6 for visual rhythm
  across all topbar chips.
- TranslationChip: drop isLocal warning path — both engines now
  run the translate-and-polish step (local routes through DeepSeek
  via ProviderConfig.localModeProviderId).
- OnboardingView: cloud engine branch now wraps the translation
  row in the same surface card chrome as the local branch.
- Strings: drop keyboard.models.warming (no longer referenced).

DeepSeek key pre-fill deferred to a follow-up.

OSGKeyboard/Views/OnboardingView.swift

@@ -742,6 +742,11 @@ private struct APISetupPage: View {
                     // step through DeepSeek, so the constraint is gone).
                     // Wrapped in the same surface card chrome as the
                     // APISettingsCard above for visual symmetry.
+                    //
+                    // v0.2.1 final review (topbar cleanup pass): the
+                    // surface card chrome is owned by `translationSection`
+                    // itself, so both branches get it for free — no
+                    // per-branch duplication.
                     if config.isTranslationRowVisible {
                         translationSection
                             .padding(.horizontal, Spacing.lg)

OSGKeyboard/Views/ProviderPickerSection.swift

@@ -10,15 +10,20 @@ struct ProviderPickerSection: View {
     @ObservedObject var config: ProviderConfig
 
     var body: some View {
+        // v0.2.1 follow-up: filter out presets marked as
+        // `isUserSelectable == false` so a future "DeepSeek key
+        // pre-fill" preset (or similar) can ship in `presets` without
+        // showing up in the picker.
+        let visiblePresets = LLMProvider.presets.filter { $0.isUserSelectable }
         VStack(spacing: 0) {
-            ForEach(Array(LLMProvider.presets.enumerated()), id: \.element.id) { index, provider in
+            ForEach(Array(visiblePresets.enumerated()), id: \.element.id) { index, provider in
                 Button {
                     select(provider)
                 } label: {
                     row(provider, selected: provider.id == config.providerId)
                 }
                 .buttonStyle(.plain)
-                if index < LLMProvider.presets.count - 1 {
+                if index < visiblePresets.count - 1 {
                     Divider().background(palette.divider)
                 }
             }

OSGKeyboardExt/Views/KeyboardRootView.swift

@@ -80,7 +80,13 @@ public struct KeyboardRootView: View {
             // and doubles as both the on/off switch and the target-
             // language picker (Menu pattern matches LocaleChip so the
             // top bar stays visually consistent).
-            TranslationChip(state: state)
+            // v0.2.1 final review: only render the chip when translation
+            // is actually on. Off-by-default keeps the top bar compact
+            // for users who don't need translation; the menu still lives
+            // in onboarding so the feature is discoverable.
+            if state.translationEnabled {
+                TranslationChip(state: state)
+            }
             Spacer(minLength: 0)
             StatusBadge(phase: state.phase, onDeviceSupported: state.onDeviceSupported)
             Button(action: state.openSettings) {
@@ -231,13 +237,6 @@ private struct TranscriptLine: View {
                     }
                     .buttonStyle(.plain)
                     .accessibilityHint(ExtL10n.text("keyboard.models.downloadHint"))
-                } else if isLocalEngine, localModelsReady, !localModelsLoaded {
-                    HStack(spacing: 6) {
-                        ProgressView().controlSize(.mini).tint(palette.textSecondary)
-                        ExtL10n.text("keyboard.models.warming")
-                            .font(TypeStyle.caption)
-                            .foregroundStyle(palette.textSecondary)
-                    }
                 } else if flowSessionActive {
                     ExtL10n.text("keyboard.placeholder.idle")
                         .font(TypeStyle.caption)
@@ -418,7 +417,7 @@ private struct StatusBadge: View {
                 .foregroundStyle(palette.textSecondary)
         }
         .padding(.horizontal, Spacing.xs)
-        .padding(.vertical, 3)
+        .padding(.vertical, 4)
         .background(palette.surface, in: Capsule())
         .overlay(Capsule().stroke(palette.divider, lineWidth: 0.5))
     }
@@ -437,8 +436,8 @@ private struct CloudEngineChip: View {
         .font(TypeStyle.caption2)
         .foregroundStyle(palette.accent)
         .padding(.horizontal, Spacing.xs + 2)
-        .padding(.vertical, 5)
-        .frame(minHeight: 26)
+        .padding(.vertical, 6)
+        .frame(minHeight: 28)
         .background(palette.accent.opacity(0.15), in: Capsule())
         .overlay(Capsule().stroke(palette.accent.opacity(0.35), lineWidth: 0.5))
     }
@@ -457,8 +456,8 @@ private struct LocalEngineChip: View {
         .font(TypeStyle.caption2)
         .foregroundStyle(palette.accent)
         .padding(.horizontal, Spacing.xs + 2)
-        .padding(.vertical, 5)
-        .frame(minHeight: 26)
+        .padding(.vertical, 6)
+        .frame(minHeight: 28)
         .background(palette.accent.opacity(0.15), in: Capsule())
         .overlay(Capsule().stroke(palette.accent.opacity(0.35), lineWidth: 0.5))
     }
@@ -504,8 +503,8 @@ private struct LocaleChip: View {
             .font(TypeStyle.caption2)
             .foregroundStyle(palette.textPrimary)
             .padding(.horizontal, Spacing.xs + 2)
-            .padding(.vertical, 5)
-            .frame(minHeight: 26)
+            .padding(.vertical, 6)
+            .frame(minHeight: 28)
             .background(palette.surfaceElevated, in: Capsule())
             .overlay(Capsule().stroke(palette.divider, lineWidth: 0.5))
         }

OSGKeyboardExt/Views/TranslationChip.swift

@@ -23,7 +23,7 @@
 //   • on (any engine) → accent fill, "→ EN" / "→ 日本語" style label
 //
 // Stays in the same visual family as `CloudEngineChip` / `LocaleChip`
-// (Capsule + 26 pt min height + 5 pt vertical padding) so the top bar
+// (Capsule + 28 pt min height + 6 pt vertical padding) so the top bar
 // doesn't grow when translation is enabled.
 
 import SwiftUI
@@ -63,22 +63,21 @@ struct TranslationChip: View {
     @ViewBuilder
     private var label: some View {
         let target = TranslationLanguageCatalog.resolve(state.translationTargetLocaleId)
-        let isLocal = state.isLocalEngine
         let enabled = state.translationEnabled
 
         HStack(spacing: 4) {
             Image(systemName: enabled ? "character.bubble" : "character.bubble.fill")
-            Text(chipLabel(target: target, enabled: enabled, isLocal: isLocal))
+            Text(chipLabel(target: target, enabled: enabled))
             Image(systemName: "chevron.down")
                 .font(.system(size: 8, weight: .bold))
         }
         .font(TypeStyle.caption2)
-        .foregroundStyle(foreground(enabled: enabled, isLocal: isLocal))
+        .foregroundStyle(foreground(enabled: enabled))
         .padding(.horizontal, Spacing.xs + 2)
-        .padding(.vertical, 5)
-        .frame(minHeight: 26)
-        .background(background(enabled: enabled, isLocal: isLocal), in: Capsule())
-        .overlay(Capsule().stroke(stroke(enabled: enabled, isLocal: isLocal), lineWidth: 0.5))
+        .padding(.vertical, 6)
+        .frame(minHeight: 28)
+        .background(background(enabled: enabled), in: Capsule())
+        .overlay(Capsule().stroke(stroke(enabled: enabled), lineWidth: 0.5))
     }
 
     /// Active selection id — the chip derives "on" from a non-off
@@ -94,11 +93,7 @@ struct TranslationChip: View {
         return language.nativeName
     }
 
-    private func chipLabel(target: TranslationLanguage, enabled: Bool, isLocal: Bool) -> String {
-        // v0.2.1 follow-up: with the local engine now routing the
-        // polish / translate step through DeepSeek, the chip shows
-        // the same "→EN"-style label on both engines. There's no
-        // "needs cloud" hint path anymore.
+    private func chipLabel(target: TranslationLanguage, enabled: Bool) -> String {
         if !enabled {
             return ExtL10n.string("keyboard.translation.off")
         }
@@ -125,24 +120,17 @@ struct TranslationChip: View {
         }
     }
 
-    private func foreground(enabled: Bool, isLocal: Bool) -> Color {
-        // v0.2.1 follow-up: the chip no longer needs a "warning" path
-        // for local + on — both engines share the accent treatment
-        // now. `isLocal` is kept in the signature so callers don't
-        // need to change; it's intentionally unused below.
-        _ = isLocal
+    private func foreground(enabled: Bool) -> Color {
         if enabled { return palette.accent }
         return palette.textPrimary
     }
 
-    private func background(enabled: Bool, isLocal: Bool) -> Color {
-        _ = isLocal
+    private func background(enabled: Bool) -> Color {
         if enabled { return palette.accent.opacity(0.15) }
         return palette.surfaceElevated
     }
 
-    private func stroke(enabled: Bool, isLocal: Bool) -> Color {
-        _ = isLocal
+    private func stroke(enabled: Bool) -> Color {
         if enabled { return palette.accent.opacity(0.35) }
         return palette.divider
     }

OSGKeyboardExt/en.lproj/Keyboard.strings

@@ -121,7 +121,6 @@
 "keyboard.placeholder.cloudBadge" = "Cloud";
 "keyboard.models.notDownloaded" = "On-device models not downloaded";
 "keyboard.models.downloadHint" = "Open OSGKeyboard to download models";
-"keyboard.models.warming" = "Loading models…";
 "keyboard.rec" = "REC";
 "keyboard.space" = "Space";
 "keyboard.denied.mic" = "Mic denied";

OSGKeyboardExt/zh-Hans.lproj/Keyboard.strings

@@ -121,7 +121,6 @@
 "keyboard.placeholder.cloudBadge" = "云端";
 "keyboard.models.notDownloaded" = "本地模型尚未下载";
 "keyboard.models.downloadHint" = "打开 OSGKeyboard 下载模型";
-"keyboard.models.warming" = "正在加载模型…";
 "keyboard.rec" = "REC";
 "keyboard.space" = "空格";
 "keyboard.denied.mic" = "麦克风被拒绝";

OSGKeyboardShared/Models/LLMProvider.swift

@@ -14,6 +14,12 @@ public struct LLMProvider: Identifiable, Codable, Hashable, Sendable {
     public let apiKeyURL: URL?
     /// Optional short blurb shown under the provider name in the picker.
     public let blurb: String?
+    /// Whether this preset should appear in user-facing provider pickers
+    /// (settings / onboarding). Defaults to `true` so the existing
+    /// `presets` array keeps its public surface area; future passes can
+    /// mark e.g. a DeepSeek key-pre-fill preset as `false` to hide it
+    /// from the picker without touching call sites.
+    public let isUserSelectable: Bool
 
     public init(
         id: String,
@@ -21,7 +27,8 @@ public struct LLMProvider: Identifiable, Codable, Hashable, Sendable {
         defaultBaseURL: String,
         defaultModel: String,
         apiKeyURL: URL? = nil,
-        blurb: String? = nil
+        blurb: String? = nil,
+        isUserSelectable: Bool = true
     ) {
         self.id = id
         self.name = name
@@ -29,6 +36,7 @@ public struct LLMProvider: Identifiable, Codable, Hashable, Sendable {
         self.defaultModel = defaultModel
         self.apiKeyURL = apiKeyURL
         self.blurb = blurb
+        self.isUserSelectable = isUserSelectable
     }
 
     public static let presets: [LLMProvider] = [