feat: IMCore bridge via dylib injection for typing indicators

Makefile

@@ -1,15 +1,17 @@
 SHELL := /bin/bash
 
-.PHONY: help format lint test build imsg clean
+.PHONY: help format lint test build imsg clean build-dylib install
 
 help:
 	@printf "%s\n" \
-		"make format  - swift format in-place" \
-		"make lint    - swift format lint + swiftlint" \
-		"make test    - sync version, patch deps, run swift test" \
-		"make build   - universal release build into bin/" \
-		"make imsg    - clean rebuild + run debug binary (ARGS=...)" \
-		"make clean   - swift package clean"
+		"make format     - swift format in-place" \
+		"make lint       - swift format lint + swiftlint" \
+		"make test       - sync version, patch deps, run swift test" \
+		"make build      - universal release build into bin/" \
+		"make build-dylib - build injectable dylib for Messages.app" \
+		"make imsg       - clean rebuild + run debug binary (ARGS=...)" \
+		"make install    - build release binary and install to /usr/local/bin" \
+		"make clean      - swift package clean"
 
 format:
 	swift format --in-place --recursive Sources Tests
@@ -24,13 +26,26 @@ test:
 	scripts/patch-deps.sh
 	swift test
 
-build:
+build: build-dylib
 	scripts/generate-version.sh
 	swift package resolve
 	scripts/patch-deps.sh
 	scripts/build-universal.sh
 
-imsg:
+# Build injectable dylib for Messages.app (DYLD_INSERT_LIBRARIES).
+# Uses arm64e architecture to match Messages.app on Apple Silicon.
+# Requires SIP disabled on the target machine to inject into system apps.
+build-dylib:
+	@echo "Building imsg-bridge-helper.dylib (injectable)..."
+	@mkdir -p .build/release
+	@clang -dynamiclib -arch arm64e -fobjc-arc \
+		-Wno-arc-performSelector-leaks \
+		-framework Foundation \
+		-o .build/release/imsg-bridge-helper.dylib \
+		Sources/IMsgHelper/IMsgInjected.m
+	@echo "Built .build/release/imsg-bridge-helper.dylib"
+
+imsg: build-dylib
 	scripts/generate-version.sh
 	swift package resolve
 	scripts/patch-deps.sh
@@ -40,3 +55,16 @@ imsg:
 
 clean:
 	swift package clean
+	@rm -f .build/release/imsg-bridge-helper.dylib
+
+install: build-dylib
+	@echo "Building release binary..."
+	scripts/generate-version.sh
+	swift package resolve
+	scripts/patch-deps.sh
+	swift build -c release --product imsg
+	@echo "Installing imsg to /usr/local/bin..."
+	@mkdir -p /usr/local/bin /usr/local/lib
+	@cp .build/release/imsg /usr/local/bin/imsg
+	@cp .build/release/imsg-bridge-helper.dylib /usr/local/lib/imsg-bridge-helper.dylib
+	@echo "Installed. Run 'imsg launch' to enable advanced features."

Sources/IMsgCore/IMCoreBridge.swift

@@ -0,0 +1,143 @@
+import Foundation
+
+public enum IMCoreBridgeError: Error, CustomStringConvertible {
+  case dylibNotFound
+  case connectionFailed(String)
+  case chatNotFound(String)
+  case operationFailed(String)
+
+  public var description: String {
+    switch self {
+    case .dylibNotFound:
+      return "imsg-bridge-helper.dylib not found. Build with: make build-dylib"
+    case .connectionFailed(let error):
+      return "Connection to Messages.app failed: \(error)"
+    case .chatNotFound(let id):
+      return "Chat not found: \(id)"
+    case .operationFailed(let reason):
+      return "Operation failed: \(reason)"
+    }
+  }
+}
+
+/// Bridge to IMCore via DYLD injection into Messages.app.
+///
+/// Communicates with an injected dylib inside Messages.app via file-based IPC.
+/// The dylib has full access to IMCore because it runs within the Messages.app
+/// context with proper entitlements.
+///
+/// Requires:
+/// - SIP disabled (for `DYLD_INSERT_LIBRARIES` on system apps)
+/// - The `imsg-bridge-helper.dylib` built via `make build-dylib`
+public final class IMCoreBridge: @unchecked Sendable {
+  public static let shared = IMCoreBridge()
+
+  private let launcher = MessagesLauncher.shared
+
+  /// Whether the dylib exists on disk (does not check if Messages.app is running).
+  public var isAvailable: Bool {
+    let possiblePaths = [
+      "/usr/local/lib/imsg-bridge-helper.dylib",
+      ".build/release/imsg-bridge-helper.dylib",
+      ".build/debug/imsg-bridge-helper.dylib",
+    ]
+    return possiblePaths.contains { FileManager.default.fileExists(atPath: $0) }
+  }
+
+  private init() {}
+
+  // MARK: - Commands
+
+  /// Set typing indicator for a conversation.
+  public func setTyping(for handle: String, typing: Bool) async throws {
+    let params: [String: Any] = [
+      "handle": handle,
+      "typing": typing,
+    ]
+    _ = try await sendCommand(action: "typing", params: params)
+  }
+
+  /// Mark all messages as read in a conversation.
+  public func markAsRead(handle: String) async throws {
+    _ = try await sendCommand(action: "read", params: ["handle": handle])
+  }
+
+  /// List all available chats (for debugging).
+  public func listChats() async throws -> [[String: Any]] {
+    let response = try await sendCommand(action: "list_chats", params: [:])
+    return response["chats"] as? [[String: Any]] ?? []
+  }
+
+  /// Get detailed status from the injected helper.
+  public func getStatus() async throws -> [String: Any] {
+    return try await sendCommand(action: "status", params: [:])
+  }
+
+  /// Check availability and return a diagnostic message.
+  public func checkAvailability() -> (available: Bool, message: String) {
+    let possiblePaths = [
+      "/usr/local/lib/imsg-bridge-helper.dylib",
+      ".build/release/imsg-bridge-helper.dylib",
+      ".build/debug/imsg-bridge-helper.dylib",
+    ]
+
+    var dylibPath: String?
+    for path in possiblePaths {
+      if FileManager.default.fileExists(atPath: path) {
+        dylibPath = path
+        break
+      }
+    }
+
+    guard dylibPath != nil else {
+      return (
+        false,
+        """
+        imsg-bridge-helper.dylib not found. To build:
+        1. make build-dylib
+        2. Restart imsg
+
+        Note: Advanced features require:
+        - SIP disabled (for DYLD injection)
+        - Full Disk Access granted to Terminal
+        """
+      )
+    }
+
+    if launcher.isInjectedAndReady() {
+      return (true, "Connected to Messages.app. IMCore features available.")
+    }
+
+    do {
+      try launcher.ensureRunning()
+      return (true, "Messages.app launched with injection. IMCore features available.")
+    } catch let error as MessagesLauncherError {
+      return (false, error.description)
+    } catch {
+      return (false, "Failed to connect to Messages.app: \(error.localizedDescription)")
+    }
+  }
+
+  // MARK: - Private
+
+  private func sendCommand(
+    action: String, params: [String: Any]
+  ) async throws -> [String: Any] {
+    do {
+      let response = try await launcher.sendCommand(action: action, params: params)
+
+      if response["success"] as? Bool == true {
+        return response
+      }
+
+      let error = response["error"] as? String ?? "Unknown error"
+      if error.contains("Chat not found") {
+        let handle = params["handle"] as? String ?? "unknown"
+        throw IMCoreBridgeError.chatNotFound(handle)
+      }
+      throw IMCoreBridgeError.operationFailed(error)
+    } catch let error as MessagesLauncherError {
+      throw IMCoreBridgeError.connectionFailed(error.description)
+    }
+  }
+}