fix(m10): item-scope take-FX fingerprint; Windows path case-fold; comments

Item scope now reads the active take's FX chain via TakeFX_* (new
fxChainIdentityForItems helper), not the owning track's chain.
normalizeSlashes lowercases on _WIN32 for detectParent. Stale
comments corrected; case-fold tests added.

tests/test_capture_paths.cpp

@@ -18,12 +18,40 @@ static int g_fail = 0;
     std::printf("FAIL line %d: %s\n", __LINE__, #cond); ++g_fail; } } while(0)
 
 static void testNormalizeSlashes() {
+#ifdef _WIN32
+    // On Windows paths are lowercased for case-insensitive comparison.
+    CHECK(normalizeSlashes("C:\\a\\b") == "c:/a/b");
+    CHECK(normalizeSlashes("a/b/c") == "a/b/c");
+    CHECK(normalizeSlashes("a/b/") == "a/b");        // trailing slash stripped
+    CHECK(normalizeSlashes("a\\b\\") == "a/b");       // backslash + trailing
+    CHECK(normalizeSlashes("/") == "/");              // lone root preserved
+    CHECK(normalizeSlashes("") == "");                // empty stays empty
+#else
     CHECK(normalizeSlashes("C:\\a\\b") == "C:/a/b");
     CHECK(normalizeSlashes("a/b/c") == "a/b/c");
-    CHECK(normalizeSlashes("a/b/") == "a/b");       // trailing slash stripped
-    CHECK(normalizeSlashes("a\\b\\") == "a/b");      // backslash + trailing
-    CHECK(normalizeSlashes("/") == "/");             // lone root preserved
-    CHECK(normalizeSlashes("") == "");               // empty stays empty
+    CHECK(normalizeSlashes("a/b/") == "a/b");
+    CHECK(normalizeSlashes("a\\b\\") == "a/b");
+    CHECK(normalizeSlashes("/") == "/");
+    CHECK(normalizeSlashes("") == "");
+#endif
+}
+
+// Windows case-folding: paths differing only in casing must compare equal after
+// normalizeSlashes, since Windows paths are case-insensitive. On non-Windows the
+// function is case-preserving (filesystem is case-sensitive).
+static void testNormalizeSlashesCaseFolding() {
+#ifdef _WIN32
+    // Drive letter and component casing differences are neutralized.
+    CHECK(normalizeSlashes("C:/Foo/BAR.wav") == normalizeSlashes("c:/foo/bar.wav"));
+    CHECK(normalizeSlashes("C:/Foo/BAR.wav") == "c:/foo/bar.wav");
+    // Mixed-case input produces consistently lowercase output.
+    CHECK(normalizeSlashes("C:\\Users\\Daniel\\Proj\\File.WAV")
+          == "c:/users/daniel/proj/file.wav");
+#else
+    // Non-Windows: case is preserved exactly (case-sensitive filesystem).
+    CHECK(normalizeSlashes("C:/Foo/BAR.wav") != normalizeSlashes("c:/foo/bar.wav"));
+    CHECK(normalizeSlashes("C:/Foo/BAR.wav") == "C:/Foo/BAR.wav");
+#endif
 }
 
 static void testSanitizeStem() {
@@ -57,7 +85,12 @@ static void testDeriveRelativePathIsProjectRelative() {
 static void testDeriveAbsoluteDirJoinsProjectDir() {
     BankPaths p = deriveBankPaths("C:\\Users\\d\\proj", "kick", "");
     // Backslashes normalized; bank subfolder appended; no trailing slash.
+    // On Windows the drive-letter + components are lowercased by normalizeSlashes.
+#ifdef _WIN32
+    CHECK(p.absoluteDir == "c:/users/d/proj/reasampler_bank");
+#else
     CHECK(p.absoluteDir == "C:/Users/d/proj/reasampler_bank");
+#endif
     // No unique tag -> stem has no trailing "_".
     CHECK(p.fileName == "kick.wav");
     CHECK(p.relativePath == "reasampler_bank/kick.wav");
@@ -116,7 +149,15 @@ static void testFileStem() {
 
 static void testResolveBankFileAgainstProjectDir() {
     // A relative index entry resolves to <projectDir>/<relativePath>, forward-
-    // slashed, regardless of the input slash style.
+    // slashed, regardless of the input slash style. On Windows the result is also
+    // lowercased (Windows paths are case-insensitive; normalizeSlashes folds them).
+#ifdef _WIN32
+    CHECK(resolveBankFile("C:\\Users\\d\\proj", "reasampler_bank/kick.wav")
+          == "c:/users/d/proj/reasampler_bank/kick.wav");
+    // Backslashes in the stored relative path are normalized on resolution.
+    CHECK(resolveBankFile("C:/p", "reasampler_bank\\a.wav")
+          == "c:/p/reasampler_bank/a.wav");
+#else
     CHECK(resolveBankFile("C:\\Users\\d\\proj", "reasampler_bank/kick.wav")
           == "C:/Users/d/proj/reasampler_bank/kick.wav");
     CHECK(resolveBankFile("/home/d/proj", "reasampler_bank/mix.wav")
@@ -127,6 +168,7 @@ static void testResolveBankFileAgainstProjectDir() {
     // Backslashes in the stored relative path are normalized on resolution.
     CHECK(resolveBankFile("/p", "reasampler_bank\\a.wav")
           == "/p/reasampler_bank/a.wav");
+#endif
 }
 
 static void testResolveBankFileRejectsEmptyInputs() {
@@ -159,10 +201,16 @@ static void testResolveAgainstNewProjectDirAfterSaveAs() {
 static void testRelocationPlanForSaveAs() {
     // Save-As to a different directory: relocation is needed; both bank dirs are
     // <projectDir>/reasampler_bank, forward-slashed, no trailing slash.
+    // On Windows the drive-letter and path components are lowercased.
     BankRelocation r = deriveRelocationPlan("C:\\old\\proj", "C:/new/proj");
     CHECK(r.needed);
+#ifdef _WIN32
+    CHECK(r.oldBankDir == "c:/old/proj/reasampler_bank");
+    CHECK(r.newBankDir == "c:/new/proj/reasampler_bank");
+#else
     CHECK(r.oldBankDir == "C:/old/proj/reasampler_bank");
     CHECK(r.newBankDir == "C:/new/proj/reasampler_bank");
+#endif
 }
 
 static void testRelocationPlanNotNeededForSaveInPlace() {
@@ -501,6 +549,7 @@ static void testHashWavContentDomainSeparationFromWholeFile() {
 
 int main() {
     testNormalizeSlashes();
+    testNormalizeSlashesCaseFolding();
     testSanitizeStem();
     testDeriveRelativePathIsProjectRelative();
     testDeriveAbsoluteDirJoinsProjectDir();