fix(dotprompt-dart,dotprompt-java,dotprompt-rs): support dotted partial names

dart/dotprompt/lib/src/dotprompt.dart

@@ -200,7 +200,7 @@ class Dotprompt {
 
   /// Resolves partial references in a template.
   Future<void> _resolvePartials(String template) async {
-    final partialPattern = RegExp(r"\{\{>\s*([a-zA-Z0-9_-]+)");
+    final partialPattern = RegExp(r"\{\{>\s*([a-zA-Z0-9_.-]+)");
     final matches = partialPattern.allMatches(template);
 
     for (final match in matches) {

java/com/google/dotprompt/Dotprompt.java

@@ -674,7 +674,7 @@ private CompletableFuture<Void> resolvePartialsAsync(String template, Set<String
   private Set<String> identifyPartials(String template) {
     Set<String> partials = new HashSet<>();
     // Match {{> partialName}} or {{> partialName context}}
-    Pattern pattern = Pattern.compile("\\{\\{>\\s*([a-zA-Z0-9_-]+)");
+    Pattern pattern = Pattern.compile("\\{\\{>\\s*([a-zA-Z0-9_.-]+)");
     Matcher matcher = pattern.matcher(template);
     while (matcher.find()) {
       partials.add(matcher.group(1));

rs/dotprompt/src/dotprompt.rs

@@ -552,7 +552,7 @@ impl Dotprompt {
     pub fn identify_partials(&self, template: &str) -> std::collections::HashSet<String> {
         let mut partials = std::collections::HashSet::new();
         // Simple regex-based partial detection: {{> partialName}}
-        let re = regex::Regex::new(r"\{\{>\s*([a-zA-Z_][a-zA-Z0-9_]*)\s*\}\}")
+        let re = regex::Regex::new(r"\{\{>\s*([a-zA-Z_][a-zA-Z0-9_.]*)\s*\}\}")
             .expect("internal regex pattern should compile");
         for cap in re.captures_iter(template) {
             if let Some(name) = cap.get(1) {

spec/partials.yaml

@@ -34,6 +34,23 @@
             content:
               [{ text: "Hello from a partial! This is the main template.\n" }]
 
+# Tests that partial names support the full filename regex: letters, digits,
+# underscores, hyphens, and dots (e.g., topic-2.sub_topic).
+- name: partial_name_with_full_regex
+  template: |
+    {{> Topic-2.sub_topic}} This is the main template.
+  partials:
+    Topic-2.sub_topic: "Hello from a complex-named partial!"
+  tests:
+    - desc: renders a partial whose name contains letters, digits, dots, underscores, and hyphens
+      data:
+        input: {}
+      expect:
+        messages:
+          - role: user
+            content:
+              [{ text: "Hello from a complex-named partial! This is the main template.\n" }]
+
 # Tests partial rendering with context variables passed from the main template.
 - name: partial_with_context
   template: |