remote_file kitten: correct pythonSplitExt to match os.path.splitext semantics

kittens/remote_file/ssh.go

@@ -99,23 +99,43 @@ func hostname_matches(from_hyperlink, actual string) bool {
 	return fl == al
 }
 
-// pythonSplitExt mirrors Python's os.path.splitext behavior for dotfiles.
-// For a file like "/x/.bashrc" (basename ".bashrc"), Python returns ("/x/.bashrc", "").
-// Go's filepath.Ext would return (".bashrc", "/x/"), losing the filename.
-// Rule: if basename starts with '.' and has no other dots, treat extension as empty.
+// pythonSplitExt mirrors Python's os.path.splitext behavior exactly.
+// Algorithm: skip all leading dots in basename; find last dot in remainder;
+// if found, split at that dot; otherwise no extension.
+// Examples:
+//   "/x/.bashrc" → ("/x/.bashrc", "")          [1 leading dot, no dot in remainder]
+//   "/x/.bashrc.bak" → ("/x/.bashrc", ".bak") [1 leading dot, 1 dot in remainder]
+//   "/x/a.b.c" → ("/x/a.b", ".c")             [0 leading dots, last dot at position 3]
+//   "....txt" → ("....txt", "")                [4 leading dots, no dot in remainder]
 func pythonSplitExt(path string) (string, string) {
-	ext := filepath.Ext(path)
-	if ext == "" {
-		return path, ""
-	}
 	basename := filepath.Base(path)
-	// If basename starts with '.' and has exactly one dot (the leading dot),
-	// then this is a dotfile with no extension.
-	if strings.HasPrefix(basename, ".") && strings.Count(basename, ".") == 1 {
+	dir := filepath.Dir(path)
+
+	// Skip all leading dots in basename
+	i := 0
+	for i < len(basename) && basename[i] == '.' {
+		i++
+	}
+
+	// Find the last dot in the remainder (after leading dots)
+	remainder := basename[i:]
+	idx := strings.LastIndex(remainder, ".")
+
+	if idx == -1 {
+		// No extension found
 		return path, ""
 	}
-	base := strings.TrimSuffix(path, ext)
-	return base, ext
+
+	// Extension starts at position i + idx in the original basename
+	extStart := i + idx
+	baseName := basename[:extStart]
+	ext := basename[extStart:]
+
+	// Reconstruct the full path
+	if dir == "." {
+		return baseName, ext
+	}
+	return filepath.Join(dir, baseName), ext
 }
 
 func auto_rename_dest(dest string, exists func(string) bool) string {

kittens/remote_file/ssh_test.go

@@ -95,3 +95,35 @@ func TestParseConnDataSSHKittenEdge(t *testing.T) {
 		t.Fatalf("ssh kitten edge case (single item): %+v, SSHKittenCmdline=%v", c, c.SSHKittenCmdline)
 	}
 }
+
+func TestPythonSplitExt(t *testing.T) {
+	// Table-driven test for pythonSplitExt matching os.path.splitext semantics.
+	// Expected values from Python 3: python3 -c "import os; print(os.path.splitext(f))" for each.
+	// Reference run: 2026-08-12
+	for _, tc := range []struct {
+		input    string
+		wantBase string
+		wantExt  string
+	}{
+		// Dotfiles with no extension in remainder (leading dots only)
+		{".bashrc", ".bashrc", ""},
+		{"..bashrc", "..bashrc", ""},
+		{"...", "...", ""},
+		{"..", "..", ""},
+		{"....txt", "....txt", ""}, // 4 leading dots, then "txt" with no dot
+
+		// Dotfiles with extension in remainder
+		{".bashrc.bak", ".bashrc", ".bak"},
+
+		// Normal files
+		{"a.b.c", "a.b", ".c"},
+		{"a.txt", "a", ".txt"},
+		{"plain", "plain", ""},
+	} {
+		base, ext := pythonSplitExt(tc.input)
+		if base != tc.wantBase || ext != tc.wantExt {
+			t.Fatalf("pythonSplitExt(%q):\n  got (%q, %q)\n  want (%q, %q)",
+				tc.input, base, ext, tc.wantBase, tc.wantExt)
+		}
+	}
+}