fix(crew): only report real template variables in fetch_inputs

lib/crewai/src/crewai/crew.py

@@ -7,7 +7,6 @@
 from hashlib import md5
 import json
 from pathlib import Path
-import re
 from typing import (
     TYPE_CHECKING,
     Annotated,
@@ -142,7 +141,10 @@ def get_supported_content_types(provider: str, api: str | None = None) -> list[s
     signal_end,
     signal_error,
 )
-from crewai.utilities.string_utils import sanitize_tool_name
+from crewai.utilities.string_utils import (
+    TEMPLATE_VARIABLE_PATTERN,
+    sanitize_tool_name,
+)
 from crewai.utilities.task_output_storage_handler import TaskOutputStorageHandler
 from crewai.utilities.training_handler import CrewTrainingHandler
 
@@ -1971,21 +1973,25 @@ def fetch_inputs(self) -> set[str]:
         'role', 'goal', and 'backstory'.
 
         Returns a set of all discovered placeholder names.
+
+        Only valid template variables are reported — the same pattern used by
+        ``interpolate_only`` to substitute them. Literal braces (e.g. embedded
+        JSON examples or output schemas) are not interpolated, so they are not
+        treated as required inputs.
         """
-        placeholder_pattern = re.compile(r"\{(.+?)}")
         required_inputs: set[str] = set()
 
         # Scan tasks for inputs
         for task in self.tasks:
             # description and expected_output might contain e.g. {topic}, {user_name}
             text = f"{task.description or ''} {task.expected_output or ''}"
-            required_inputs.update(placeholder_pattern.findall(text))
+            required_inputs.update(TEMPLATE_VARIABLE_PATTERN.findall(text))
 
         # Scan agents for inputs
         for agent in self.agents:
             # role, goal, backstory might have placeholders like {role_detail}, etc.
             text = f"{agent.role or ''} {agent.goal or ''} {agent.backstory or ''}"
-            required_inputs.update(placeholder_pattern.findall(text))
+            required_inputs.update(TEMPLATE_VARIABLE_PATTERN.findall(text))
 
         return required_inputs
 

lib/crewai/src/crewai/utilities/string_utils.py

@@ -9,7 +9,9 @@
 import unicodedata
 
 
-_VARIABLE_PATTERN: Final[re.Pattern[str]] = re.compile(r"\{([A-Za-z_][A-Za-z0-9_\-]*)}")
+TEMPLATE_VARIABLE_PATTERN: Final[re.Pattern[str]] = re.compile(
+    r"\{([A-Za-z_][A-Za-z0-9_\-]*)}"
+)
 _QUOTE_PATTERN: Final[re.Pattern[str]] = re.compile(r"[\'\"]+")
 _CAMEL_LOWER_UPPER: Final[re.Pattern[str]] = re.compile(r"([a-z])([A-Z])")
 _CAMEL_UPPER_LOWER: Final[re.Pattern[str]] = re.compile(r"([A-Z]+)([A-Z][a-z])")
@@ -134,7 +136,7 @@ def _validate_type(validate_value: Any) -> None:
             "Inputs dictionary cannot be empty when interpolating variables"
         )
 
-    variables = _VARIABLE_PATTERN.findall(input_string)
+    variables = TEMPLATE_VARIABLE_PATTERN.findall(input_string)
     result = input_string
 
     # Check if all variables exist in inputs

lib/crewai/tests/test_crew.py

@@ -3966,6 +3966,33 @@ def test_fetch_inputs():
     )
 
 
+def test_fetch_inputs_ignores_literal_braces():
+    """fetch_inputs must only report real template variables.
+
+    Literal braces (embedded JSON examples, output schemas) and non-identifier
+    braces are not interpolated by ``interpolate_only``, so they must not be
+    reported as required inputs. Otherwise ``kickoff`` accepts inputs that are
+    silently ignored, while ``fetch_inputs`` advertises placeholders that can
+    never be filled.
+    """
+    agent = Agent(
+        role="Researcher",
+        goal="Research on {topic}.",
+        backstory='Reply as JSON like {"name": "value"}.',
+    )
+
+    task = Task(
+        description='Analyze {topic} and return {"result": [1, 2, 3]}.',
+        expected_output="Summary of {topic}. Ignore {123} markers.",
+        agent=agent,
+    )
+
+    crew = Crew(agents=[agent], tasks=[task])
+
+    # Only the genuine identifier placeholder should be reported.
+    assert crew.fetch_inputs() == {"topic"}
+
+
 @pytest.mark.vcr()
 def test_task_tools_preserve_code_execution_tools():
     """