test(app): add tests for filename sanitization and invalid regex handling

- 5 tests for ProtocolGenerator filename sanitization (/, :, \, NUL)
- 2 tests for MeetingDetector graceful handling of invalid regex patterns

Author: pasrom

app/MeetingTranscriber/Tests/MeetingDetectorTests.swift

@@ -400,4 +400,38 @@ final class MeetingDetectorTests: XCTestCase {
         // Should be detectable again immediately (no cooldown)
         XCTAssertNotNil(detector.checkOnce())
     }
+
+    // MARK: - Invalid Regex Graceful Handling
+
+    func testInvalidMeetingRegexSkippedGracefully() {
+        // Invalid regex should be silently skipped, not crash
+        let badPattern = AppMeetingPattern(
+            appName: "BadApp",
+            ownerNames: ["BadApp"],
+            meetingPatterns: ["[invalid(regex"],
+            idlePatterns: [],
+        )
+        let detector = MeetingDetector(patterns: [badPattern])
+        // Should not crash, and no windows match
+        detector.windowListProvider = {
+            [makeWindow(owner: "BadApp", name: "Some Title")]
+        }
+        XCTAssertNil(detector.checkOnce())
+    }
+
+    func testMixedValidAndInvalidRegexKeepsValid() {
+        // Valid patterns still work even if some are invalid
+        let mixedPattern = AppMeetingPattern(
+            appName: "Microsoft Teams",
+            ownerNames: ["Microsoft Teams"],
+            meetingPatterns: ["[bad(", ".*\\| Microsoft Teams$"],
+            idlePatterns: [],
+        )
+        let detector = MeetingDetector(patterns: [mixedPattern], confirmationCount: 1)
+        detector.windowListProvider = {
+            [makeWindow(owner: "Microsoft Teams", name: "Standup | Microsoft Teams")]
+        }
+        // Valid regex should still match
+        XCTAssertNotNil(detector.checkOnce())
+    }
 }

app/MeetingTranscriber/Tests/ProtocolGeneratorTests.swift

@@ -100,6 +100,37 @@ final class ProtocolGeneratorTests: XCTestCase {
         XCTAssertTrue(txt.hasSuffix(".txt"))
     }
 
+    // MARK: - Filename Sanitization
+
+    func testFilenameSanitizesSlashes() {
+        let name = ProtocolGenerator.filename(title: "Code/Review", ext: "md")
+        XCTAssertFalse(name.contains("/"))
+        XCTAssertTrue(name.contains("codereview"))
+    }
+
+    func testFilenameSanitizesColons() {
+        let name = ProtocolGenerator.filename(title: "Meeting: Planning", ext: "md")
+        XCTAssertFalse(name.contains(":"))
+        XCTAssertTrue(name.contains("meeting_planning"))
+    }
+
+    func testFilenameSanitizesBackslashes() {
+        let name = ProtocolGenerator.filename(title: "Path\\Name", ext: "md")
+        XCTAssertFalse(name.contains("\\"))
+        XCTAssertTrue(name.contains("pathname"))
+    }
+
+    func testFilenameSanitizesNullBytes() {
+        let name = ProtocolGenerator.filename(title: "Test\0Title", ext: "md")
+        XCTAssertFalse(name.contains("\0"))
+        XCTAssertTrue(name.contains("testtitle"))
+    }
+
+    func testFilenameSanitizesMultipleForbiddenChars() {
+        let name = ProtocolGenerator.filename(title: "A/B:C\\D", ext: "txt")
+        XCTAssertTrue(name.hasSuffix("_abcd.txt"))
+    }
+
     // MARK: - File Save Operations
 
     func testSaveTranscript() throws {