diff --git a/.github/workflows/linux.yml b/.github/workflows/linux.yml
new file mode 100644
index 0000000..21fb3f2
--- /dev/null
+++ b/.github/workflows/linux.yml
@@ -0,0 +1,20 @@
+# Builds the non-UI products (GraphcodeKit, graphcode CLI, graphcoded) on Linux via
+# the root Package.swift — the portability gate for issue #83. The macOS app still
+# builds only through Tuist/Xcode and is not covered here.
+name: Linux
+
+on:
+  push:
+    branches: [main]
+  pull_request:
+
+jobs:
+  build:
+    runs-on: ubuntu-latest
+    container: swift:6.2
+    steps:
+      - uses: actions/checkout@v4
+      - name: Build
+        run: swift build
+      - name: Smoke-test CLI
+        run: .build/debug/graphcode
diff --git a/GraphcodeKit/Sources/DaemonBootstrap.swift b/GraphcodeKit/Sources/DaemonBootstrap.swift
index 404f7ed..ebea15e 100644
--- a/GraphcodeKit/Sources/DaemonBootstrap.swift
+++ b/GraphcodeKit/Sources/DaemonBootstrap.swift
@@ -1,5 +1,10 @@
 import Foundation
 
+// launchd, quarantine xattrs, `~/Library/LaunchAgents` — this whole mechanism is the
+// macOS app's drag-to-Applications install, and only the app calls it. A Linux install
+// story (systemd user unit or equivalent) would be a sibling, not a port of this.
+#if os(macOS)
+
 /// Installs the helpers a shipped `graphcode.app` carries inside itself — `graphcoded` and
 /// `zmx` — and loads the daemon, so dragging the app to `/Applications` is the whole
 /// installation.
@@ -226,3 +231,5 @@ public enum DaemonBootstrap {
     process.waitUntilExit()
   }
 }
+
+#endif
diff --git a/GraphcodeKit/Sources/IPC/DaemonSocketClient.swift b/GraphcodeKit/Sources/IPC/DaemonSocketClient.swift
index a9b9470..99a2558 100644
--- a/GraphcodeKit/Sources/IPC/DaemonSocketClient.swift
+++ b/GraphcodeKit/Sources/IPC/DaemonSocketClient.swift
@@ -2,6 +2,8 @@ import Foundation
 
 #if canImport(Darwin)
   import Darwin
+#else
+  import Glibc
 #endif
 
 /// A short-lived client for `graphcoded`'s socket — what the `graphcode` CLI talks
@@ -90,12 +92,19 @@ public struct DaemonSocketClient: Sendable {
       throw ClientError.daemonNotRunning
     }
 
-    let descriptor = socket(AF_UNIX, SOCK_STREAM, 0)
+    #if canImport(Darwin)
+      let descriptor = socket(AF_UNIX, SOCK_STREAM, 0)
+    #else
+      // Glibc imports SOCK_STREAM as the `__socket_type` enum, not an Int32.
+      let descriptor = socket(AF_UNIX, Int32(SOCK_STREAM.rawValue), 0)
+    #endif
     guard descriptor >= 0 else { throw ClientError.connectionFailed(errno: errno) }
 
     var address = sockaddr_un()
     address.sun_family = sa_family_t(AF_UNIX)
-    address.sun_len = UInt8(MemoryLayout<sockaddr_un>.size)
+    #if canImport(Darwin)
+      address.sun_len = UInt8(MemoryLayout<sockaddr_un>.size)
+    #endif
     withUnsafeMutablePointer(to: &address.sun_path) { field in
       field.withMemoryRebound(
         to: CChar.self, capacity: MemoryLayout.size(ofValue: field.pointee)
@@ -127,7 +136,7 @@ public struct DaemonSocketClient: Sendable {
   private static func applyReceiveTimeout(_ timeout: TimeInterval, to descriptor: Int32) {
     var interval = timeval(
       tv_sec: Int(timeout),
-      tv_usec: Int32((timeout - timeout.rounded(.down)) * 1_000_000))
+      tv_usec: suseconds_t((timeout - timeout.rounded(.down)) * 1_000_000))
     setsockopt(
       descriptor, SOL_SOCKET, SO_RCVTIMEO, &interval, socklen_t(MemoryLayout<timeval>.size))
   }
diff --git a/GraphcodeKit/Sources/IPC/FramedMessageIO.swift b/GraphcodeKit/Sources/IPC/FramedMessageIO.swift
index d25206e..93d9f74 100644
--- a/GraphcodeKit/Sources/IPC/FramedMessageIO.swift
+++ b/GraphcodeKit/Sources/IPC/FramedMessageIO.swift
@@ -2,6 +2,8 @@ import Foundation
 
 #if canImport(Darwin)
   import Darwin
+#else
+  import Glibc
 #endif
 
 /// Length-prefixed framing over a raw socket file descriptor — a 4-byte big-endian
diff --git a/GraphcodeKit/Sources/Sessions/PTYProcessSession.swift b/GraphcodeKit/Sources/Sessions/PTYProcessSession.swift
index 4d66304..28414fa 100644
--- a/GraphcodeKit/Sources/Sessions/PTYProcessSession.swift
+++ b/GraphcodeKit/Sources/Sessions/PTYProcessSession.swift
@@ -1,6 +1,11 @@
-import Darwin
 import Foundation
 
+#if canImport(Darwin)
+  import Darwin
+#else
+  import Glibc
+#endif
+
 /// One event out of a running PTY-backed process: either a chunk of raw output, or a
 /// terminal lifecycle transition. See docs/04-cli-backends.md.
 public enum PTYSessionEvent: Sendable, Equatable {
@@ -40,6 +45,9 @@ public final class PTYProcessSession: @unchecked Sendable {
   ) throws {
     var master: Int32 = 0
     var slave: Int32 = 0
+    // Portable as-is: Glibc's module includes pty.h, and glibc ≥ 2.34 ships openpty
+    // in libc proper, so no libutil link is needed on Linux. The POSIX pt* trio is
+    // not an option — stdlib.h's feature-macro guards keep it out of Swift's Glibc.
     guard openpty(&master, &slave, nil, nil, nil) == 0 else {
       throw SessionError.failedToOpenPTY
     }
diff --git a/Package.resolved b/Package.resolved
new file mode 100644
index 0000000..3ace216
--- /dev/null
+++ b/Package.resolved
@@ -0,0 +1,24 @@
+{
+  "originHash" : "2ef7a1c0cce984b320f4784a7c1bd827ec8f3e73eaba10904b94d12d131c9bea",
+  "pins" : [
+    {
+      "identity" : "swift-collections",
+      "kind" : "remoteSourceControl",
+      "location" : "https://github.com/apple/swift-collections",
+      "state" : {
+        "revision" : "a0cb0954ecb21e4e31b0070e6ed5674e8556685a",
+        "version" : "1.6.0"
+      }
+    },
+    {
+      "identity" : "swift-identified-collections",
+      "kind" : "remoteSourceControl",
+      "location" : "https://github.com/pointfreeco/swift-identified-collections",
+      "state" : {
+        "revision" : "322d9ffeeba85c9f7c4984b39422ec7cc3c56597",
+        "version" : "1.1.1"
+      }
+    }
+  ],
+  "version" : 3
+}
diff --git a/Package.swift b/Package.swift
new file mode 100644
index 0000000..1c24e4d
--- /dev/null
+++ b/Package.swift
@@ -0,0 +1,47 @@
+// swift-tools-version: 6.0
+import PackageDescription
+
+// SwiftPM manifest for the non-UI products — GraphcodeKit, the `graphcode` CLI, and
+// `graphcoded` — so they build on Linux (and anywhere else swift-corelibs Foundation
+// runs), where Tuist and Xcode don't. The macOS app keeps building through
+// `Project.swift`; Tuist resolves its dependencies from `Tuist/Package.swift` and
+// ignores this file. See issue #83.
+let package = Package(
+  name: "graphcode",
+  platforms: [.macOS(.v15)],
+  products: [
+    .library(name: "GraphcodeKit", targets: ["GraphcodeKit"]),
+    .executable(name: "graphcode", targets: ["graphcode-cli"]),
+    .executable(name: "graphcoded", targets: ["graphcoded"]),
+  ],
+  dependencies: [
+    .package(
+      url: "https://github.com/pointfreeco/swift-identified-collections",
+      from: "1.1.0"
+    )
+  ],
+  targets: [
+    .target(
+      name: "GraphcodeKit",
+      dependencies: [
+        .product(name: "IdentifiedCollections", package: "swift-identified-collections")
+      ],
+      path: "GraphcodeKit/Sources",
+      // Language mode 5 to match how Tuist/Xcode builds these same sources today;
+      // moving the tree to strict mode 6 is its own change, not the Linux port's.
+      swiftSettings: [.swiftLanguageMode(.v5)]
+    ),
+    .executableTarget(
+      name: "graphcode-cli",
+      dependencies: ["GraphcodeKit"],
+      path: "graphcode-cli/Sources",
+      swiftSettings: [.swiftLanguageMode(.v5)]
+    ),
+    .executableTarget(
+      name: "graphcoded",
+      dependencies: ["GraphcodeKit"],
+      path: "graphcoded/Sources",
+      swiftSettings: [.swiftLanguageMode(.v5)]
+    ),
+  ]
+)
diff --git a/graphcoded/Sources/main.swift b/graphcoded/Sources/main.swift
index 5258a86..f871017 100644
--- a/graphcoded/Sources/main.swift
+++ b/graphcoded/Sources/main.swift
@@ -3,6 +3,8 @@ import GraphcodeKit
 
 #if canImport(Darwin)
   import Darwin
+#else
+  import Glibc
 #endif
 
 // graphcoded — the graphcode orchestrator daemon.
@@ -37,14 +39,21 @@ func fail(_ message: String) -> Never {
   exit(1)
 }
 
-let socketDescriptor = socket(AF_UNIX, SOCK_STREAM, 0)
+#if canImport(Darwin)
+  let socketDescriptor = socket(AF_UNIX, SOCK_STREAM, 0)
+#else
+  // Glibc imports SOCK_STREAM as the `__socket_type` enum, not an Int32.
+  let socketDescriptor = socket(AF_UNIX, Int32(SOCK_STREAM.rawValue), 0)
+#endif
 guard socketDescriptor >= 0 else {
   fail("failed to create socket (errno \(errno))")
 }
 
 var address = sockaddr_un()
 address.sun_family = sa_family_t(AF_UNIX)
-address.sun_len = UInt8(MemoryLayout<sockaddr_un>.size)
+#if canImport(Darwin)
+  address.sun_len = UInt8(MemoryLayout<sockaddr_un>.size)
+#endif
 
 let path = socketURL.path
 withUnsafeMutablePointer(to: &address.sun_path) { pathField in