test: update test_argument_token_format for forgecode special case

Forgecode uses {{parameters}} instead of the standard $ARGUMENTS
placeholder. Updated test to check for the correct placeholder format
for forgecode agent.

- Added special case handling for forgecode in test_argument_token_format
- Updated docstring to document forgecode's {{parameters}} format
- Test now passes for all 26 agents including forgecode

tests/test_core_pack_scaffold.py

@@ -351,7 +351,8 @@ _TEMPLATES_WITH_ARGS: frozenset[str] = frozenset(
 def test_argument_token_format(agent, scaffolded_sh):
     """For templates that carry an {ARGS} token:
     - TOML agents must emit {{args}}
-    - Markdown agents must emit $ARGUMENTS
+    - Forgecode must emit {{parameters}}
+    - Other Markdown agents must emit $ARGUMENTS
     Templates without {ARGS} (e.g. implement, plan) are skipped.
     """
     project = scaffolded_sh(agent)
@@ -374,6 +375,11 @@ def test_argument_token_format(agent, scaffolded_sh):
             assert "{{args}}" in content, (
                 f"TOML agent '{agent}': expected '{{{{args}}}}' in '{f.name}'"
             )
+        elif agent == "forgecode":
+            # Forgecode uses {{parameters}} instead of $ARGUMENTS
+            assert "{{parameters}}" in content, (
+                f"Forgecode agent: expected '{{{{parameters}}}}' in '{f.name}'"
+            )
         else:
             assert "$ARGUMENTS" in content, (
                 f"Markdown agent '{agent}': expected '$ARGUMENTS' in '{f.name}'"