fix: preserve log trim boundaries and verify cached audio

Author: Mr-Sunglasses

Sources/VocaMac/Services/Logger.swift

@@ -66,10 +66,16 @@ enum LogFileStore {
         let size = try handle.seekToEnd()
         guard size > maximumBytes else { return }
 
-        try handle.seek(toOffset: size - UInt64(maximumBytes))
+        // Inspect the preceding byte so a cutoff at a complete line does not
+        // discard that line. Only drop a partial leading entry.
+        try handle.seek(toOffset: size - UInt64(maximumBytes) - 1)
+        let precedingByte = try handle.read(upToCount: 1)?.first
         var tail = try handle.readToEnd() ?? Data()
-        if let newline = tail.firstIndex(of: 0x0A) {
+        if precedingByte != 0x0A, let newline = tail.firstIndex(of: 0x0A) {
             tail.removeSubrange(tail.startIndex...newline)
+        } else if precedingByte != 0x0A {
+            // No complete entry fits; avoid writing a partial UTF-8 sequence.
+            tail.removeAll()
         }
         try tail.write(to: url, options: .atomic)
     }
@@ -363,7 +369,7 @@ final class VocaLogger {
             )) ?? []
             for file in files {
                 let name = file.deletingPathExtension().lastPathComponent
-                guard name.hasPrefix("vocamac."),
+                guard file.pathExtension == "log", name.hasPrefix("vocamac."),
                       let index = Int(name.dropFirst("vocamac.".count)),
                       index > maxRotatedFiles else {
                     continue

Tests/VocaMacTests/LoggerTests.swift

@@ -77,6 +77,22 @@ final class LogLevelTests: XCTestCase {
 
 final class VocaLoggerTests: XCTestCase {
 
+    func testTrimPreservesCompleteLineAtExactCutoff() throws {
+        let file = FileManager.default.temporaryDirectory.appendingPathComponent(UUID().uuidString)
+        defer { try? FileManager.default.removeItem(at: file) }
+        try Data("old\nनमस्ते\n".utf8).write(to: file)
+        try LogFileStore.trimToTail(at: file, maximumBytes: Data("नमस्ते\n".utf8).count)
+        XCTAssertEqual(try String(contentsOf: file, encoding: .utf8), "नमस्ते\n")
+    }
+
+    func testTrimDoesNotKeepPartialUnicodeEntry() throws {
+        let file = FileManager.default.temporaryDirectory.appendingPathComponent(UUID().uuidString)
+        defer { try? FileManager.default.removeItem(at: file) }
+        try Data("नमस्ते".utf8).write(to: file)
+        try LogFileStore.trimToTail(at: file, maximumBytes: 2)
+        XCTAssertEqual(try Data(contentsOf: file), Data())
+    }
+
     func testRotationReplacesFullBackupSetAndPreservesOrder() throws {
         let directory = FileManager.default.temporaryDirectory
             .appendingPathComponent(UUID().uuidString, isDirectory: true)

Tests/VocaMacTests/ServiceTests.swift

@@ -446,6 +446,29 @@ extension XCTestCase {
 
 final class AudioEngineTests: XCTestCase {
 
+    func testCachedConversionMatchesFreshConverterAcrossBuffersAndRouteChanges() throws {
+        let cache = AudioConverterCache()
+        for rate in [48_000.0, 48_000.0, 44_100.0, 44_100.0] {
+            let format = try XCTUnwrap(AVAudioFormat(standardFormatWithSampleRate: rate, channels: 1))
+            let input = try XCTUnwrap(AVAudioPCMBuffer(pcmFormat: format, frameCapacity: 4_096))
+            input.frameLength = 4_096
+            let samples = try XCTUnwrap(input.floatChannelData?[0])
+            for frame in 0..<4_096 {
+                samples[frame] = Float(sin(Double(frame) * 2 * .pi * 440 / rate)) * 0.25
+            }
+            let fresh = try XCTUnwrap(AudioEngine.convertToWhisperFormat(input, from: format))
+            let cached = try XCTUnwrap(AudioEngine.convertToWhisperFormat(
+                input, from: format, converterProvider: { cache.converter(from: $0, to: $1) }
+            ))
+            XCTAssertEqual(cached.frameLength, fresh.frameLength)
+            let expected = try XCTUnwrap(fresh.floatChannelData?[0])
+            let actual = try XCTUnwrap(cached.floatChannelData?[0])
+            for frame in 0..<Int(fresh.frameLength) {
+                XCTAssertEqual(actual[frame], expected[frame], accuracy: 0.000_001)
+            }
+        }
+    }
+
     func testConverterCacheReusesMatchingFormatAndReplacesChangedFormat() throws {
         let cache = AudioConverterCache()
         let destination = try XCTUnwrap(AVAudioFormat(