fix: avoid unix socket path too long (use /tmp)

Sources/GitwCore/GitRunner.swift

@@ -64,8 +64,14 @@ public enum GitRunner {
             }
 
             let nonce = randomNonce()
-            let dir = FileManager.default.temporaryDirectory.appendingPathComponent("gitw-\(getpid())-\(UUID().uuidString)")
-            try FileManager.default.createDirectory(at: dir, withIntermediateDirectories: false, attributes: [FileAttributeKey.posixPermissions: 0o700])
+            // Use /tmp to keep Unix domain socket paths short enough for sockaddr_un.
+            // (macOS limits sun_path to ~104 bytes)
+            let shortId = String(UUID().uuidString.prefix(8))
+            let dir = URL(fileURLWithPath: "/tmp")
+                .appendingPathComponent("gitw-\(getpid())-\(shortId)")
+            try FileManager.default.createDirectory(at: dir,
+                                                    withIntermediateDirectories: false,
+                                                    attributes: [FileAttributeKey.posixPermissions: 0o700])
             tmpDir = dir
             let sock = dir.appendingPathComponent("askpass.sock").path
 

Tests/GitwCoreTests/SocketPathLengthTests.swift

@@ -0,0 +1,17 @@
+import Foundation
+import Testing
+@testable import GitwCore
+
+struct SocketPathLengthTests {
+    @Test
+    func brokerSocketPathStaysUnderUnixDomainLimit() {
+        // Best-effort guardrail: sockaddr_un.sun_path is ~104 bytes on macOS.
+        // We can't assert the OS constant easily, but we can ensure our constructed
+        // path is comfortably below the limit.
+        let pid = 12345
+        let shortId = "abcdef12"
+        let dir = URL(fileURLWithPath: "/tmp").appendingPathComponent("gitw-\(pid)-\(shortId)")
+        let sock = dir.appendingPathComponent("askpass.sock").path
+        #expect(sock.utf8.count < 100)
+    }
+}