feat: add Apple FoundationModels on-device LLM adapter

LilAgents/AgentSession.swift

@@ -3,7 +3,7 @@ import Foundation
 // MARK: - Provider
 
 enum AgentProvider: String, CaseIterable {
-    case claude, codex, copilot, gemini, opencode, openclaw
+    case claude, codex, copilot, gemini, opencode, openclaw, foundationModels
 
     private static let defaultsKey = "selectedProvider"
 
@@ -19,12 +19,13 @@ enum AgentProvider: String, CaseIterable {
 
     var displayName: String {
         switch self {
-        case .claude:   return "Claude"
-        case .codex:    return "Codex"
-        case .copilot:  return "Copilot"
-        case .gemini:   return "Gemini"
-        case .opencode: return "OpenCode"
-        case .openclaw: return "OpenClaw"
+        case .claude:           return "Claude"
+        case .codex:            return "Codex"
+        case .copilot:          return "Copilot"
+        case .gemini:           return "Gemini"
+        case .opencode:         return "OpenCode"
+        case .openclaw:         return "OpenClaw"
+        case .foundationModels: return "On-Device"
         }
     }
 
@@ -43,12 +44,13 @@ enum AgentProvider: String, CaseIterable {
 
     var binaryName: String {
         switch self {
-        case .claude:   return "claude"
-        case .codex:    return "codex"
-        case .copilot:  return "copilot"
-        case .gemini:   return "gemini"
-        case .opencode: return "opencode"
-        case .openclaw: return "openclaw"
+        case .claude:           return "claude"
+        case .codex:            return "codex"
+        case .copilot:          return "copilot"
+        case .gemini:           return "gemini"
+        case .opencode:         return "opencode"
+        case .openclaw:         return "openclaw"
+        case .foundationModels: return ""
         }
     }
 
@@ -65,6 +67,15 @@ enum AgentProvider: String, CaseIterable {
                 availability[provider] = OpenClawConfig.load().authToken.isEmpty == false
                 continue
             }
+            // FoundationModels is framework-based, not a local binary
+            if provider == .foundationModels {
+                if #available(macOS 26.0, *) {
+                    availability[provider] = FoundationModelsSession.isAvailable()
+                } else {
+                    availability[provider] = false
+                }
+                continue
+            }
             group.enter()
             let home = FileManager.default.homeDirectoryForCurrentUser.path
             ShellEnvironment.findBinary(name: provider.binaryName, fallbackPaths: [
@@ -83,6 +94,12 @@ enum AgentProvider: String, CaseIterable {
 
     var isAvailable: Bool {
         if self == .openclaw { return OpenClawConfig.load().authToken.isEmpty == false }
+        if self == .foundationModels {
+            if #available(macOS 26.0, *) {
+                return FoundationModelsSession.isAvailable()
+            }
+            return false
+        }
         return AgentProvider.availability[self] ?? false
     }
 
@@ -105,6 +122,8 @@ enum AgentProvider: String, CaseIterable {
             return "To install, run this in Terminal:\n  curl -fsSL https://opencode.ai/install | bash"
         case .openclaw:
             return "OpenClaw is a self-hosted AI gateway.\n\nInstall: npm install -g openclaw\nStart:   openclaw gateway run\n\nDocs: https://docs.openclaw.ai"
+        case .foundationModels:
+            return "Apple Intelligence requires macOS 26+ on Apple Silicon\nwith Apple Intelligence enabled in System Settings."
         }
     }
 
@@ -116,6 +135,13 @@ enum AgentProvider: String, CaseIterable {
         case .gemini:   return GeminiSession()
         case .opencode: return OpenCodeSession()
         case .openclaw: return OpenClawSession()
+        case .foundationModels:
+            if #available(macOS 26.0, *) {
+                return FoundationModelsSession()
+            } else {
+                // Fallback — should never reach here if isAvailable is checked first
+                return ClaudeSession()
+            }
         }
     }
 }

LilAgents/FoundationModelsSession.swift

@@ -0,0 +1,148 @@
+import Foundation
+#if canImport(FoundationModels)
+import FoundationModels
+#endif
+
+/// On-device LLM session using Apple FoundationModels (macOS 26+).
+/// Adapts the FoundationModels streaming API to the lil-agents
+/// callback-based AgentSession protocol.
+@available(macOS 26.0, *)
+class FoundationModelsSession: AgentSession {
+    private(set) var isRunning = false
+    private(set) var isBusy = false
+    var history: [AgentMessage] = []
+
+    var onText: ((String) -> Void)?
+    var onError: ((String) -> Void)?
+    var onToolUse: ((String, [String: Any]) -> Void)?
+    var onToolResult: ((String, Bool) -> Void)?
+    var onSessionReady: (() -> Void)?
+    var onTurnComplete: (() -> Void)?
+    var onProcessExit: (() -> Void)?
+
+    #if canImport(FoundationModels)
+    private var session: LanguageModelSession?
+    #endif
+
+    private var currentTask: Task<Void, Never>?
+
+    // MARK: - Availability
+
+    static func isAvailable() -> Bool {
+        #if canImport(FoundationModels)
+        switch SystemLanguageModel.default.availability {
+        case .available: return true
+        default: return false
+        }
+        #else
+        return false
+        #endif
+    }
+
+    // MARK: - AgentSession
+
+    func start() {
+        guard !isRunning else { return }
+
+        #if canImport(FoundationModels)
+        switch SystemLanguageModel.default.availability {
+        case .available:
+            let s = LanguageModelSession()
+            s.prewarm()
+            session = s
+            isRunning = true
+            onSessionReady?()
+        default:
+            let msg = AgentProvider.foundationModels.installInstructions
+            onError?(msg)
+            history.append(AgentMessage(role: .error, text: msg))
+        }
+        #else
+        let msg = "FoundationModels framework not available on this system."
+        onError?(msg)
+        history.append(AgentMessage(role: .error, text: msg))
+        #endif
+    }
+
+    func send(message: String) {
+        guard isRunning else { return }
+        guard !isBusy else { return }
+
+        isBusy = true
+        history.append(AgentMessage(role: .user, text: message))
+
+        #if canImport(FoundationModels)
+        guard let session = session else {
+            isBusy = false
+            onError?("On-device session is not available.")
+            return
+        }
+
+        currentTask = Task { [weak self] in
+            await self?.streamResponse(session: session, prompt: message)
+        }
+        #else
+        isBusy = false
+        onError?("FoundationModels framework not available.")
+        #endif
+    }
+
+    func terminate() {
+        currentTask?.cancel()
+        currentTask = nil
+        #if canImport(FoundationModels)
+        session = nil
+        #endif
+        isRunning = false
+        isBusy = false
+        onProcessExit?()
+    }
+
+    // MARK: - Streaming
+
+    #if canImport(FoundationModels)
+    @MainActor
+    private func streamResponse(session: LanguageModelSession, prompt: String) async {
+        var accumulated = ""
+        do {
+            let stream = session.streamResponse(to: prompt)
+            for try await snapshot in stream {
+                guard !Task.isCancelled else {
+                    isBusy = false
+                    onTurnComplete?()
+                    return
+                }
+                let full = snapshot.content
+                let delta = String(full.dropFirst(accumulated.count))
+                if !delta.isEmpty {
+                    onText?(delta)
+                }
+                accumulated = full
+            }
+            // Stream completed successfully
+            if !accumulated.isEmpty {
+                history.append(AgentMessage(role: .assistant, text: accumulated))
+            }
+            isBusy = false
+            onTurnComplete?()
+        } catch {
+            isBusy = false
+            onError?(error.localizedDescription)
+        }
+    }
+    #endif
+
+    // MARK: - Context Reset
+
+    /// Recreate the inner LanguageModelSession for /clear support.
+    /// The outer session object (and its callback wiring) stays alive.
+    func resetContext() {
+        currentTask?.cancel()
+        currentTask = nil
+        #if canImport(FoundationModels)
+        let s = LanguageModelSession()
+        s.prewarm()
+        session = s
+        #endif
+    }
+}

LilAgents/WalkerCharacter.swift

@@ -506,6 +506,21 @@ class WalkerCharacter {
     }
 
     func resetSession() {
+        // For FoundationModels, reset context without full teardown
+        if #available(macOS 26.0, *),
+           let fmSession = session as? FoundationModelsSession {
+            fmSession.resetContext()
+            currentStreamingText = ""
+            showingCompletion = false
+            currentPhrase = ""
+            completionBubbleExpiry = 0
+            hideBubble()
+            terminalView?.resetState()
+            terminalView?.showSessionMessage()
+            fmSession.history = []
+            return
+        }
+
         session?.terminate()
         session = nil
         currentStreamingText = ""

lil-agents.xcodeproj/project.pbxproj

@@ -27,6 +27,7 @@
 		A10000010000000000000036 /* OpenCodeSession.swift in Sources */ = {isa = PBXBuildFile; fileRef = A10000020000000000000035 /* OpenCodeSession.swift */; };
 		A10000010000000000000037 /* DockVisibility.swift in Sources */ = {isa = PBXBuildFile; fileRef = A10000020000000000000036 /* DockVisibility.swift */; };
 		A10000010000000000000038 /* OpenClawSession.swift in Sources */ = {isa = PBXBuildFile; fileRef = A10000020000000000000037 /* OpenClawSession.swift */; };
+		A10000010000000000000039 /* FoundationModelsSession.swift in Sources */ = {isa = PBXBuildFile; fileRef = A10000020000000000000038 /* FoundationModelsSession.swift */; };
 /* End PBXBuildFile section */
 
 /* Begin PBXFileReference section */
@@ -51,6 +52,7 @@
 		A10000020000000000000035 /* OpenCodeSession.swift */ = {isa = PBXFileReference; lastKnownFileType = sourcecode.swift; path = OpenCodeSession.swift; sourceTree = "<group>"; };
 		A10000020000000000000036 /* DockVisibility.swift */ = {isa = PBXFileReference; lastKnownFileType = sourcecode.swift; path = DockVisibility.swift; sourceTree = "<group>"; };
 		A10000020000000000000037 /* OpenClawSession.swift */ = {isa = PBXFileReference; lastKnownFileType = sourcecode.swift; path = OpenClawSession.swift; sourceTree = "<group>"; };
+		A10000020000000000000038 /* FoundationModelsSession.swift */ = {isa = PBXFileReference; lastKnownFileType = sourcecode.swift; path = FoundationModelsSession.swift; sourceTree = "<group>"; };
 		A10000030000000000000001 /* lil agents.app */ = {isa = PBXFileReference; explicitFileType = wrapper.application; includeInIndex = 0; path = "lil agents.app"; sourceTree = BUILT_PRODUCTS_DIR; };
 /* End PBXFileReference section */
 
@@ -88,6 +90,7 @@
 				A10000020000000000000034 /* GeminiSession.swift */,
 				A10000020000000000000035 /* OpenCodeSession.swift */,
 				A10000020000000000000037 /* OpenClawSession.swift */,
+				A10000020000000000000038 /* FoundationModelsSession.swift */,
 				A10000020000000000000036 /* DockVisibility.swift */,
 				A10000020000000000000023 /* TerminalView.swift */,
 				A10000020000000000000024 /* WalkerCharacter.swift */,
@@ -200,6 +203,7 @@
 				A10000010000000000000036 /* OpenCodeSession.swift in Sources */,
 				A10000010000000000000037 /* DockVisibility.swift in Sources */,
 				A10000010000000000000038 /* OpenClawSession.swift in Sources */,
+				A10000010000000000000039 /* FoundationModelsSession.swift in Sources */,
 				A10000010000000000000023 /* TerminalView.swift in Sources */,
 				A10000010000000000000024 /* WalkerCharacter.swift in Sources */,
 				A10000010000000000000025 /* LilAgentsController.swift in Sources */,