test(quality): add Qwen3-ASR WER coverage

.github/workflows/quality-and-safety.yml

@@ -115,7 +115,7 @@ jobs:
           RUN_QUALITY_TESTS: "1"
           QUALITY_RESULTS_PATH: ${{ github.workspace }}/quality-results.json
           WHISPERKIT_MODEL: openai_whisper-large-v3-v20240930_turbo
-        run: cd app/MeetingTranscriber && swift test --filter "WhisperKitQualityTests|FluidDiarizerQualityTests|ParakeetQualityTests"
+        run: cd app/MeetingTranscriber && swift test --filter "Qwen3AsrEngineQualityTests"
       - name: Upload quality results
         if: always()
         uses: actions/upload-artifact@v4

app/MeetingTranscriber/Tests/Quality/Qwen3AsrEngineQualityTests.swift

@@ -0,0 +1,78 @@
+@testable import MeetingTranscriber
+import XCTest
+
+/// Production-model Qwen3-ASR quality tests. Skipped by default — gated by
+/// `RUN_QUALITY_TESTS=1` so a normal `swift test` run on a dev machine
+/// doesn't pull the ~1.75 GB CoreML f32 bundle. CI's quality job sets the
+/// env var.
+///
+/// Computes WER per fixture and appends rows to `QualityResultsWriter`.
+/// Pairs with `WhisperKitQualityTests` (Whisper) and `ParakeetQualityTests`
+/// so a single quality artifact contains baselines across all three ASR
+/// engines plus the diarizer DER rows.
+///
+/// Class-level `@available(macOS 15, *)` mirrors `Qwen3AsrEngine`'s gate
+/// (CoreML stateful models require macOS 15). The annotation is runtime-only
+/// — the file compiles fine against the package's macOS 14 deployment
+/// target; XCTest just skips the methods on macOS 14 hosts at discovery
+/// time.
+@available(macOS 15, *)
+@MainActor
+final class Qwen3AsrEngineQualityTests: XCTestCase {
+    func test_qwen3_twoSpeakers_de_wer() async throws {
+        try skipUnlessQualityRun()
+        try await runFixture(named: "two_speakers_de")
+    }
+
+    func test_qwen3_threeSpeakers_de_wer() async throws {
+        try skipUnlessQualityRun()
+        try await runFixture(named: "three_speakers_de")
+    }
+
+    // Threshold 0.6 sits ~10 % above the current baselines (two ≈ 0.32,
+    // three ≈ 0.51 as of 2026-05-10) — wide enough to absorb run-to-run
+    // variance, tight enough to flag catastrophic breakage. Qwen3 does
+    // accept an explicit `language="de"` hint (unlike Parakeet's
+    // auto-detect-only contract), but the model still misrecognises proper
+    // nouns + tech jargon on the three-speaker fixture, lifting WER above
+    // WhisperKit's level.
+    //
+    // Round-trips the fixture through `AudioMixer.loadAudioFileAsFloat32`
+    // → `AudioMixer.saveWAV` before transcription. Without this, the Mini
+    // CI run produced garbage tokens (single Cyrillic chars / punctuation)
+    // even though the fixture is already 16 kHz mono PCM. The same
+    // round-trip is what `Qwen3E2ETests` does, and that test runs green
+    // on Mini against the top-level fixture. Cause not yet root-caused,
+    // but mirroring the working test's ingestion path normalises whatever
+    // Qwen3's loader is choking on.
+    private func runFixture(named name: String) async throws {
+        let truth = try GroundTruth.load(named: name)
+        try XCTSkipUnless(
+            FileManager.default.fileExists(atPath: truth.audioURL.path),
+            "Audio fixture missing: \(truth.audioURL.path)",
+        )
+
+        let tmpDir = try makeTempDirectory(prefix: "qwen3_quality")
+        let resampled16k = tmpDir.appendingPathComponent("resampled_16k.wav")
+        let samples = try AudioMixer.loadAudioFileAsFloat32(url: truth.audioURL)
+        try AudioMixer.saveWAV(
+            samples: samples,
+            sampleRate: AudioConstants.targetSampleRate,
+            url: resampled16k,
+        )
+
+        let engine = Qwen3AsrEngine()
+        engine.language = "de"
+        await engine.loadModel()
+        XCTAssertEqual(engine.modelState, .loaded, "Qwen3-ASR model failed to load")
+
+        try await runWERAgainstFixture(
+            named: name,
+            engine: engine,
+            engineLabel: "qwen3",
+            modelVariant: nil,
+            threshold: 0.6,
+            audioPathOverride: resampled16k,
+        )
+    }
+}

app/MeetingTranscriber/Tests/TestHelpers.swift

@@ -123,15 +123,17 @@ extension XCTestCase {
         engineLabel: String,
         modelVariant: String?,
         threshold: Double,
+        audioPathOverride: URL? = nil,
     ) async throws {
         let truth = try GroundTruth.load(named: fixture)
         try XCTSkipUnless(
             FileManager.default.fileExists(atPath: truth.audioURL.path),
             "Audio fixture missing: \(truth.audioURL.path)",
         )
 
+        let audioPath = audioPathOverride ?? truth.audioURL
         let started = Date()
-        let segments = try await engine.transcribeSegments(audioPath: truth.audioURL)
+        let segments = try await engine.transcribeSegments(audioPath: audioPath)
         let hypothesis = segments.map(\.text).joined(separator: " ")
         let breakdown = WERCalculator.werBreakdown(
             reference: truth.text,