Use SystemPath for PluginConfig.

Convert PluginConfig.init from URL to FilePath, following the migration
pattern from apple#1480 (HostDNSResolver), apple#1518 (PacketFilter), and
discussion apple#1481.

- PluginConfig.init?(configURL: URL) → init?(configPath: FilePath)
- DefaultPluginFactory.findConfigURL → findConfigPath (returns FilePath?)
- Both internal call sites (DefaultPluginFactory, AppBundlePluginFactory)
  updated; bridge from URL to FilePath stays at the directory boundary
  since broader PluginFactory conversion is tracked separately.
- Tests updated to derive FilePath from temp URL.

Author: chrisgeo

Sources/ContainerPlugin/PluginConfig.swift

@@ -16,6 +16,7 @@
 
 //
 import Foundation
+import SystemPackage
 import TOML
 
 /// PluginConfig details all of the fields to describe and register a plugin.
@@ -109,17 +110,17 @@ extension PluginConfig {
 extension PluginConfig {
     /// Initialize from a config file, selecting the decoder based on file extension.
     /// Supports `.toml` (via TOMLDecoder) and `.json` (via JSONDecoder).
-    public init?(configURL: URL) throws {
+    public init?(configPath: FilePath) throws {
         let fm = FileManager.default
-        if !fm.fileExists(atPath: configURL.path) {
+        if !fm.fileExists(atPath: configPath.string) {
             return nil
         }
 
-        guard let data = fm.contents(atPath: configURL.path) else {
+        guard let data = fm.contents(atPath: configPath.string) else {
             return nil
         }
 
-        switch configURL.pathExtension {
+        switch configPath.extension {
         case "toml":
             guard let content = String(data: data, encoding: .utf8) else {
                 return nil

Sources/ContainerPlugin/PluginFactory.swift

@@ -16,6 +16,7 @@
 
 import Foundation
 import Logging
+import SystemPackage
 
 /// Describes the configuration and binary file locations for a plugin.
 public protocol PluginFactory: Sendable {
@@ -35,8 +36,8 @@ public struct DefaultPluginFactory: PluginFactory {
         self.logger = logger
     }
 
-    /// Returns the URL of the first config file found in `directory`, preferring TOML over JSON.
-    static func findConfigURL(in directory: URL, logger: Logger) -> URL? {
+    /// Returns the path of the first config file found in `directory`, preferring TOML over JSON.
+    static func findConfigPath(in directory: URL, logger: Logger) -> FilePath? {
         let fm = FileManager.default
         for filename in configFilenames {
             let url = directory.appending(path: filename)
@@ -47,7 +48,7 @@ public struct DefaultPluginFactory: PluginFactory {
                         metadata: ["path": "\(url.path)"]
                     )
                 }
-                return url
+                return FilePath(url.path)
             }
         }
         return nil
@@ -56,11 +57,11 @@ public struct DefaultPluginFactory: PluginFactory {
     public func create(installURL: URL) throws -> Plugin? {
         let fm = FileManager.default
 
-        guard let configURL = Self.findConfigURL(in: installURL, logger: logger) else {
+        guard let configPath = Self.findConfigPath(in: installURL, logger: logger) else {
             return nil
         }
 
-        guard let config = try PluginConfig(configURL: configURL) else {
+        guard let config = try PluginConfig(configPath: configPath) else {
             return nil
         }
 
@@ -99,11 +100,11 @@ public struct AppBundlePluginFactory: PluginFactory {
             .appending(path: "Contents")
             .appending(path: "Resources")
 
-        guard let configURL = DefaultPluginFactory.findConfigURL(in: contentResources, logger: logger) else {
+        guard let configPath = DefaultPluginFactory.findConfigPath(in: contentResources, logger: logger) else {
             return nil
         }
 
-        guard let config = try PluginConfig(configURL: configURL) else {
+        guard let config = try PluginConfig(configPath: configPath) else {
             return nil
         }
 

Tests/ContainerPluginTests/PluginConfigTest.swift

@@ -15,6 +15,7 @@
 //===----------------------------------------------------------------------===//
 
 import Foundation
+import SystemPackage
 import Testing
 
 @testable import ContainerPlugin
@@ -35,7 +36,8 @@ struct PluginConfigTest {
             author = "Apple"
             """
         try configToml.write(to: configURL, atomically: true, encoding: .utf8)
-        let config = try #require(try PluginConfig(configURL: configURL))
+        let configPath = FilePath(configURL.path)
+        let config = try #require(try PluginConfig(configPath: configPath))
 
         #expect(config.isCLI)
         #expect(config.abstract == "Default network management service")
@@ -67,7 +69,8 @@ struct PluginConfigTest {
             description = "foo"
             """
         try configToml.write(to: configURL, atomically: true, encoding: .utf8)
-        let config = try #require(try PluginConfig(configURL: configURL))
+        let configPath = FilePath(configURL.path)
+        let config = try #require(try PluginConfig(configPath: configPath))
 
         #expect(!config.isCLI)
         #expect(config.abstract == "Default network management service")
@@ -97,8 +100,9 @@ struct PluginConfigTest {
             [invalid
             """
         try malformedToml.write(to: configURL, atomically: true, encoding: .utf8)
+        let configPath = FilePath(configURL.path)
         #expect(throws: (any Error).self) {
-            try PluginConfig(configURL: configURL)
+            try PluginConfig(configPath: configPath)
         }
     }
 
@@ -117,7 +121,8 @@ struct PluginConfigTest {
             author: "Apple"
             """
         try content.write(to: configURL, atomically: true, encoding: .utf8)
-        let config = try PluginConfig(configURL: configURL)
+        let configPath = FilePath(configURL.path)
+        let config = try PluginConfig(configPath: configPath)
         #expect(config == nil)
     }
 }