fix(sdk): use build_replacements unresolved set instead of post-scan for curly templates

The curly template formatter raised a false TemplateFormatError when a
substituted value happened to contain {{...}} patterns (e.g. template
examples or code snippets in user input).

Root cause: after substitution, compute_truly_unreplaced() re-scanned
the rendered output for {{...}} patterns and intersected with the
original placeholder set. It could not distinguish between genuinely
unreplaced placeholders and {{...}} patterns injected by substituted
values.

Fix: use the 'unresolved' set already returned by build_replacements()
to detect truly missing variables. This set is computed before
substitution, so it is immune to patterns in substituted values.

Changes:
- types.py: use unresolved from build_replacements instead of
  compute_truly_unreplaced
- handlers.py: same fix
- Remove now-unused compute_truly_unreplaced from both files
- Add unit tests covering the false-positive scenario

Fixes #3770

Author: User

sdk/agenta/sdk/types.py

@@ -646,12 +646,6 @@ def _repl(m: re.Match) -> str:
     return _PLACEHOLDER_RE.sub(_repl, template)
 
 
-def compute_truly_unreplaced(original: set, rendered: str) -> set:
-    """Only count placeholders that were in the original template and remain."""
-    now = set(extract_placeholders(rendered))
-    return original & now
-
-
 def missing_lib_hints(unreplaced: set) -> Optional[str]:
     """Suggest installing python-jsonpath if placeholders indicate json-path or json-pointer usage."""
     if any(expr.startswith("$") or expr.startswith("/") for expr in unreplaced):
@@ -722,20 +716,17 @@ def _format_with_template(self, content: str, kwargs: Dict[str, Any]) -> str:
             elif self.template_format == "curly":
                 original_placeholders = set(extract_placeholders(content))
 
-                replacements, _unresolved = build_replacements(
+                replacements, unresolved = build_replacements(
                     original_placeholders, kwargs
                 )
 
                 result = apply_replacements(content, replacements)
 
-                truly_unreplaced = compute_truly_unreplaced(
-                    original_placeholders, result
-                )
-                if truly_unreplaced:
-                    hint = missing_lib_hints(truly_unreplaced)
+                if unresolved:
+                    hint = missing_lib_hints(unresolved)
                     suffix = f" Hint: {hint}" if hint else ""
                     raise TemplateFormatError(
-                        f"Unreplaced variables in curly template: {sorted(truly_unreplaced)}.{suffix}"
+                        f"Unreplaced variables in curly template: {sorted(unresolved)}.{suffix}"
                     )
 
                 return result

sdk/agenta/sdk/workflows/handlers.py

@@ -253,12 +253,6 @@ def _repl(m: re.Match) -> str:
     return _PLACEHOLDER_RE.sub(_repl, template)
 
 
-def compute_truly_unreplaced(original: set, rendered: str) -> set:
-    """Only count placeholders that were in the original template and remain."""
-    now = set(extract_placeholders(rendered))
-    return original & now
-
-
 def missing_lib_hints(unreplaced: set) -> Optional[str]:
     """Suggest installing python-jsonpath if placeholders indicate json-path or json-pointer usage."""
     if any(expr.startswith("$") or expr.startswith("/") for expr in unreplaced):
@@ -288,18 +282,16 @@ def _format_with_template(
     elif format == "curly":
         original_placeholders = set(extract_placeholders(content))
 
-        replacements, _unresolved = build_replacements(original_placeholders, kwargs)
+        replacements, unresolved = build_replacements(original_placeholders, kwargs)
 
         result = apply_replacements(content, replacements)
 
-        truly_unreplaced = compute_truly_unreplaced(original_placeholders, result)
-
-        if truly_unreplaced:
-            hint = missing_lib_hints(truly_unreplaced)
+        if unresolved:
+            hint = missing_lib_hints(unresolved)
             suffix = f" Hint: {hint}" if hint else ""
             raise ValueError(
                 f"Template variables not found or unresolved: "
-                f"{', '.join(sorted(truly_unreplaced))}.{suffix}"
+                f"{', '.join(sorted(unresolved))}.{suffix}"
             )
 
         return result

sdk/tests/pytest/unit/test_curly_template.py

@@ -0,0 +1,56 @@
+"""Tests for curly template formatting — specifically the false-positive
+unreplaced-variable detection reported in #3770."""
+
+import pytest
+
+from agenta.sdk.types import PromptTemplate
+
+
+class TestCurlyTemplateSubstitution:
+    """Verify that substituted values containing {{...}} patterns do not
+    trigger a false TemplateFormatError."""
+
+    def test_value_containing_placeholder_pattern(self):
+        """Substituted value that looks like a placeholder should not raise."""
+        prompt = PromptTemplate(
+            user_prompt="Hello {{name}}",
+            template_format="curly",
+        )
+        result = prompt.format(name="I am {{name}}")
+        assert result.messages[-1].content == "Hello I am {{name}}"
+
+    def test_value_containing_different_placeholder(self):
+        """Substituted value with a different placeholder name should not raise."""
+        prompt = PromptTemplate(
+            user_prompt="Result: {{output}}",
+            template_format="curly",
+        )
+        result = prompt.format(output="Use {{variable}} in your template")
+        assert result.messages[-1].content == "Result: Use {{variable}} in your template"
+
+    def test_multiple_vars_one_with_placeholder_value(self):
+        """Multiple variables where one value contains placeholder syntax."""
+        prompt = PromptTemplate(
+            user_prompt="{{greeting}}, {{name}}!",
+            template_format="curly",
+        )
+        result = prompt.format(greeting="Hi", name="{{greeting}}")
+        assert result.messages[-1].content == "Hi, {{greeting}}!"
+
+    def test_genuinely_missing_variable_still_raises(self):
+        """A truly missing variable should still raise an error."""
+        prompt = PromptTemplate(
+            user_prompt="Hello {{name}}, your id is {{id}}",
+            template_format="curly",
+        )
+        with pytest.raises(Exception):
+            prompt.format(name="Alice")
+
+    def test_all_variables_provided(self):
+        """Normal case — all variables provided, no placeholder patterns in values."""
+        prompt = PromptTemplate(
+            user_prompt="Hello {{name}}",
+            template_format="curly",
+        )
+        result = prompt.format(name="World")
+        assert result.messages[-1].content == "Hello World"