fix native playback stream resolution

Tests/StreamResolverTests.swift

@@ -0,0 +1,73 @@
+import Foundation
+
+@main
+struct StreamResolverTests {
+    static func main() {
+        testClassifierPrefersObservedDirectFile()
+        testResolverSelectsUnsupportedDirectURLAndHeaders()
+        testResolverRejectsHLSOnlyResponse()
+        print("StreamResolverTests passed")
+    }
+
+    private static func testClassifierPrefersObservedDirectFile() {
+        let body: [String: Any] = [
+            "url": "https://cdn.example.test/movie.mkv?token=secret",
+            "resolverUrl": "https://addon.debridio.com/play/example"
+        ]
+        let candidate = StreamCandidate(messageBody: body)!
+        let request = StreamClassifier.playbackRequest(from: candidate, userAgent: "DreamioTest/1")!
+
+        assertEqual(request.playbackURL.absoluteString, "https://cdn.example.test/movie.mkv?token=secret")
+        assertEqual(request.headers["Referer"], "https://web.stremio.com/")
+        assertEqual(request.headers["User-Agent"], "DreamioTest/1")
+    }
+
+    private static func testResolverSelectsUnsupportedDirectURLAndHeaders() {
+        let payload: [String: Any] = [
+            "streams": [
+                [
+                    "url": "https://cdn.example.test/trailer.mp4"
+                ],
+                [
+                    "externalUrl": "https://cdn.example.test/movie.mkv?signature=secret",
+                    "behaviorHints": [
+                        "proxyHeaders": [
+                            "request": [
+                                "Referer": "https://resolver.example.test/",
+                                "User-Agent": "ResolverAgent/1"
+                            ]
+                        ]
+                    ]
+                ]
+            ]
+        ]
+
+        let stream = StremioStreamResolver.bestPlayableStream(
+            in: payload,
+            fallbackHeaders: ["Referer": "https://web.stremio.com/"]
+        )!
+
+        assertEqual(stream.playbackURL.absoluteString, "https://cdn.example.test/movie.mkv?signature=secret")
+        assertEqual(stream.headers["Referer"], "https://resolver.example.test/")
+        assertEqual(stream.headers["User-Agent"], "ResolverAgent/1")
+    }
+
+    private static func testResolverRejectsHLSOnlyResponse() {
+        let payload: [String: Any] = [
+            "streams": [
+                ["url": "https://cdn.example.test/live.m3u8"]
+            ]
+        ]
+
+        let stream = StremioStreamResolver.bestPlayableStream(
+            in: payload,
+            fallbackHeaders: ["Referer": "https://web.stremio.com/"]
+        )
+
+        assert(stream == nil, "Expected HLS-only resolver response to stay out of native playback")
+    }
+
+    private static func assertEqual<T: Equatable>(_ actual: T?, _ expected: T, file: StaticString = #file, line: UInt = #line) {
+        assert(actual == expected, "Expected \(String(describing: expected)), got \(String(describing: actual))", file: file, line: line)
+    }
+}