feat(macos): cross-registry server browse + multiselect registry filter (#583)

Ports the Web UI R1 experience into the macOS tray's Registries tab (MCP-996
parity for macOS, tracked under the v0.36.0 feedback batch):

- APIClient: searchRegistryServers (GET /registries/{id}/servers) and
  addServerFromRegistry (POST .../servers/{serverId}/add), encodeURIComponent-
  equivalent path encoding for ids with slashes.
- RegistryModels: RepositoryServer (+ neutral transport classifier mirroring
  the Web UI: remote / stdio:npm / stdio:python / stdio:docker / stdio),
  SearchRegistryServersResponse (+ per-registry 'unavailable' marker),
  AddServerResult / error decode with missing_inputs.
- ServerBrowseView: multiselect registry filter (Menu w/ check toggles +
  All/Clear), cross-registry search (fan out + merge + dedupe), registry-
  attributed result cards with transport label + Add button, and a non-fatal
  notice for registries that need a key / are unreachable. Embedded atop the
  Registries tab; the configured-registries list stays below.
- MainWindow: hidden Cmd-1..5 shortcuts to jump between sidebar sections
  (keyboard nav + enables UI-test automation to reach a section).

Verified: swiftc -O clean; 23 SwiftPM unit tests pass (transport/decode/encode);
data layer bash-checked (reference+docker return, pulse/smithery report
unavailable); ui-test MCP confirmed the app runs this build and the Cmd-3
navigation works (pixel screenshots blocked by missing Screen Recording
permission on the ui-test helper).

Refs MCP-996

Author: Dumbris

native/macos/MCPProxy/MCPProxy/API/APIClient.swift

@@ -726,4 +726,37 @@ actor APIClient {
             return .failure(code: nil, error: error.localizedDescription)
         }
     }
+
+    /// Search a single registry's servers via
+    /// `GET /api/v1/registries/{id}/servers?q=&limit=`. Throws on transport/HTTP
+    /// errors; a 200 with an `unavailable` marker (e.g. key required) is a
+    /// normal, non-throwing result that the browse view surfaces per-registry.
+    func searchRegistryServers(registryID: String, query: String, limit: Int = 20) async throws -> SearchRegistryServersResponse {
+        var params: [String] = ["limit=\(limit)"]
+        if !query.isEmpty { params.insert("q=\(query.uriComponentEncoded)", at: 0) }
+        let path = "/api/v1/registries/\(registryID.uriComponentEncoded)/servers?\(params.joined(separator: "&"))"
+        return try await fetchWrapped(path: path)
+    }
+
+    /// Add a server discovered through a registry via
+    /// `POST /api/v1/registries/{id}/servers/{serverId}/add`. Returns a
+    /// structured result (does not throw) carrying `missingInputs` when the
+    /// server needs env values the caller hasn't supplied yet.
+    func addServerFromRegistry(registryID: String, serverID: String, env: [String: String]? = nil) async -> AddServerResult {
+        var body: [String: Any] = [:]
+        if let env, !env.isEmpty { body["env"] = env }
+        let path = "/api/v1/registries/\(registryID.uriComponentEncoded)/servers/\(serverID.uriComponentEncoded)/add"
+        do {
+            let bodyData = try JSONSerialization.data(withJSONObject: body)
+            let (data, response) = try await rawRequest(path: path, method: "POST", body: bodyData)
+            if (200...299).contains(response.statusCode) { return .ok() }
+            let err = try? JSONDecoder().decode(RegistryAddServerErrorBody.self, from: data)
+            return .failure(
+                message: err?.message ?? "HTTP \(response.statusCode): \(HTTPURLResponse.localizedString(forStatusCode: response.statusCode))",
+                missingInputs: err?.missingInputs
+            )
+        } catch {
+            return .failure(message: error.localizedDescription)
+        }
+    }
 }

native/macos/MCPProxy/MCPProxy/API/RegistryModels.swift

@@ -146,3 +146,109 @@ struct ThirdPartyRegistryAck {
         defaults.set(true, forKey: Self.key)
     }
 }
+
+// MARK: - Server discovery / browse (macOS mirror of Web UI R1)
+//
+// Models `GET /api/v1/registries/{id}/servers` (per-registry search) and
+// `POST /api/v1/registries/{id}/servers/{serverId}/add`. The browse view fans
+// these out across several selected registries and merges the results.
+
+/// A server returned by a registry search. Mirrors `contracts.RepositoryServer`
+/// (only the fields the tray browse UI needs are decoded).
+struct RepositoryServer: Codable, Identifiable, Equatable {
+    let id: String
+    let name: String
+    let description: String?
+    let url: String?
+    let sourceCodeURL: String?
+    let installCmd: String?
+    let connectURL: String?
+    /// Which registry this result came from (used for per-card attribution and
+    /// as the registry id passed to the add endpoint).
+    let registry: String?
+    let requiredInputs: [RequiredInput]?
+
+    enum CodingKeys: String, CodingKey {
+        case id, name, description, url, registry
+        case sourceCodeURL = "source_code_url"
+        case installCmd = "install_cmd"
+        case connectURL = "connect_url"
+        case requiredInputs = "required_inputs"
+    }
+
+    struct RequiredInput: Codable, Equatable {
+        let name: String
+        let description: String?
+        let secret: Bool?
+    }
+
+    /// Neutral transport label mirroring the Web UI's `serverTransport` (R2):
+    /// remote / stdio:npm / stdio:python / stdio:docker / stdio.
+    var transport: String {
+        let cmd = (installCmd ?? "").trimmingCharacters(in: .whitespaces).lowercased()
+        if !cmd.isEmpty {
+            if cmd.hasPrefix("docker") { return "stdio:docker" }
+            if cmd.hasPrefix("npx") || cmd.range(of: #"(^|\s)(npm|node)(\s|$)"#, options: .regularExpression) != nil { return "stdio:npm" }
+            if cmd.hasPrefix("uvx") || cmd.hasPrefix("uv ") || cmd.range(of: #"(^|\s)(pipx?|python3?)(\s|$)"#, options: .regularExpression) != nil { return "stdio:python" }
+            return "stdio"
+        }
+        if let url, !url.isEmpty { return "remote" }
+        return "stdio"
+    }
+}
+
+/// Per-registry "unavailable" marker (e.g. key required). Mirrors
+/// `contracts.RegistryUnavailable`.
+struct RegistryUnavailable: Codable, Equatable {
+    let reason: String?
+}
+
+/// Response of `GET /api/v1/registries/{id}/servers`. Mirrors
+/// `contracts.SearchRegistryServersResponse`.
+struct SearchRegistryServersResponse: Codable {
+    let registryID: String?
+    let servers: [RepositoryServer]?
+    let total: Int?
+    let unavailable: RegistryUnavailable?
+
+    enum CodingKeys: String, CodingKey {
+        case registryID = "registry_id"
+        case servers, total, unavailable
+    }
+}
+
+/// Result of adding a server from a registry. Carries `missingInputs` when the
+/// backend rejects with `missing_required_input` so the UI can tell the user
+/// which env vars are needed (the full prompt flow is a follow-up).
+struct AddServerResult: Equatable {
+    let success: Bool
+    let message: String?
+    let missingInputs: [String]?
+
+    static func ok() -> AddServerResult { AddServerResult(success: true, message: nil, missingInputs: nil) }
+    static func failure(message: String?, missingInputs: [String]? = nil) -> AddServerResult {
+        AddServerResult(success: false, message: message, missingInputs: missingInputs)
+    }
+}
+
+/// Structured error body of a failed add-from-registry. Mirrors
+/// `contracts.RegistryAddError`.
+struct RegistryAddServerErrorBody: Decodable {
+    let code: String?
+    let message: String?
+    let missingInputs: [String]?
+    enum CodingKeys: String, CodingKey {
+        case code, message
+        case missingInputs = "missing_inputs"
+    }
+}
+
+/// JS `encodeURIComponent` equivalent for safe path-segment encoding (the Web
+/// UI uses encodeURIComponent on the registry id and server id).
+extension String {
+    var uriComponentEncoded: String {
+        let allowed = CharacterSet(charactersIn:
+            "ABCDEFGHIJKLMNOPQRSTUVWXYZabcdefghijklmnopqrstuvwxyz0123456789-_.!~*'()")
+        return addingPercentEncoding(withAllowedCharacters: allowed) ?? self
+    }
+}

native/macos/MCPProxy/MCPProxy/Views/MainWindow.swift

@@ -75,6 +75,7 @@ struct MainWindow: View {
             .accessibilityIdentifier("detail-view")
         }
         .frame(minWidth: 800, minHeight: 500)
+        .background(sidebarShortcuts)
         .onReceive(NotificationCenter.default.publisher(for: .switchToActivity)) { _ in
             selectedItem = .activity
         }
@@ -83,6 +84,24 @@ struct MainWindow: View {
         }
     }
 
+    /// Hidden ⌘1…⌘5 shortcuts to jump straight to each sidebar section. Keeps
+    /// keyboard navigation fast for users and lets UI-test automation reach a
+    /// section (the sidebar List rows aren't directly clickable via the
+    /// accessibility menu API).
+    @ViewBuilder
+    private var sidebarShortcuts: some View {
+        VStack {
+            ForEach(Array(SidebarItem.allCases.enumerated()), id: \.element) { index, item in
+                Button("") { selectedItem = item }
+                    .keyboardShortcut(KeyEquivalent(Character(String(index + 1))), modifiers: .command)
+                    .accessibilityIdentifier("sidebar-shortcut-\(item.rawValue)")
+            }
+        }
+        .opacity(0)
+        .frame(width: 0, height: 0)
+        .accessibilityHidden(true)
+    }
+
     // MARK: - Core Status Banner
 
     @ViewBuilder

native/macos/MCPProxy/MCPProxy/Views/RegistriesView.swift

@@ -49,6 +49,19 @@ struct RegistriesView: View {
                 banner(icon: "checkmark.circle.fill", tint: .green, text: success)
             }
 
+            // Browse + add servers across one or more registries (R1 parity).
+            ServerBrowseView(appState: appState, registries: registries)
+
+            HStack {
+                Text("Configured registries")
+                    .font(.scaled(.caption, scale: fontScale).bold())
+                    .foregroundStyle(.secondary)
+                Spacer()
+            }
+            .padding(.horizontal)
+            .padding(.top, 4)
+            Divider()
+
             content
         }
         .sheet(isPresented: $showAddRegistry) {