Render in place: a track's output to a new sibling, source to the bench

tests/test_capture_name.cpp

@@ -241,6 +241,41 @@ static void testEveryAwkwardStemStaysFilesystemLegal() {
     }
 }
 
+// --- captureTrackName -------------------------------------------------------
+
+static void testCaptureTrackNamePrefixesAPlainSourceName() {
+    CHECK(captureTrackName("MONEY") == "Capture MONEY");
+    CHECK(captureTrackName("bass di") == "Capture bass di");
+}
+
+static void testCaptureTrackNameIsIdempotent() {
+    // The whole point: a second render over a result track must not stack the prefix.
+    CHECK(captureTrackName("Capture MONEY") == "Capture MONEY");
+    CHECK(captureTrackName(captureTrackName("MONEY")) == "Capture MONEY");
+    // A fixed point on its own output for EVERY input, degenerate ones included.
+    for (const char* src : {"MONEY", "", "Capture", "Capture ", "Captured drums"}) {
+        const std::string once = captureTrackName(src);
+        CHECK(captureTrackName(once) == once);
+    }
+}
+
+static void testCaptureTrackNameEmptySourceHasNoTrailingSpace() {
+    // Unreachable from trackName (GetTrackName always answers "Track N"), so this is
+    // the defensive case — a bare word rather than a name ending in a space.
+    CHECK(captureTrackName("") == "Capture");
+}
+
+static void testCaptureTrackNameUnnamedSourceReadsAsCaptureTrackN() {
+    // trackName's GetTrackName fallback rides in as an ordinary name.
+    CHECK(captureTrackName("Track 7") == "Capture Track 7");
+}
+
+static void testCaptureTrackNameDoesNotMatchAMerePrefixOfTheWord() {
+    // "Captured" begins with "Capture" but not with "Capture " — it is a different
+    // name and must be prefixed like any other.
+    CHECK(captureTrackName("Captured drums") == "Capture Captured drums");
+}
+
 int main() {
     testStampIsZeroPaddedMonthDayHourMinute();
     testUnsetStampProducesNoDiscriminator();
@@ -268,6 +303,12 @@ int main() {
     testOrdinalAndMultiSourceCompose();
     testEveryAwkwardStemStaysFilesystemLegal();
 
+    testCaptureTrackNamePrefixesAPlainSourceName();
+    testCaptureTrackNameIsIdempotent();
+    testCaptureTrackNameEmptySourceHasNoTrailingSpace();
+    testCaptureTrackNameUnnamedSourceReadsAsCaptureTrackN();
+    testCaptureTrackNameDoesNotMatchAMerePrefixOfTheWord();
+
     if (g_fail == 0) std::printf("capture_name: all tests passed\n");
     else std::printf("capture_name: %d CHECK(s) FAILED\n", g_fail);
     return g_fail ? 1 : 0;