FIX: Forward the previous image to single-turn targets in TAP

pyrit/executor/attack/multi_turn/tree_of_attacks.py

@@ -686,14 +686,16 @@ async def _send_prompt_to_target_async(self, prompt: str) -> Message:
         Side Effects:
             - Sets self.last_response to the target's response text
         """
+        # Check the turn before a single-turn target gets a fresh conversation, which is always empty.
+        turn_index = 0 if (await self._is_first_turn_async()) else 1
         self._rotate_unseeded_single_turn_conversation()
 
         # Build the request message via the modality router so prior media (if any)
         # is included when the objective target accepts it.
         message = self._modality_router.build_objective_input_message(
             text=prompt,
             last_response=self.last_response,
-            turn_index=0 if (await self._is_first_turn_async()) else 1,
+            turn_index=turn_index,
         )
 
         # Send prompt with configured converters

tests/unit/executor/attack/multi_turn/test_tree_of_attacks.py

@@ -3337,15 +3337,19 @@ def _make_image_response(conversation_id: str) -> Message:
             ]
         )
 
-    async def test_node_send_prompt_to_target_forwards_prev_image(self, node_components):
-        """Objective accepting {text, image_path} gets prev image attached on turn N."""
+    @pytest.mark.parametrize("supports_multi_turn", [True, False])
+    async def test_node_send_prompt_to_target_forwards_prev_image(self, node_components, supports_multi_turn):
+        """Objective accepting {text, image_path} gets prev image attached on turn N, also when it is single-turn."""
         # Override the router to point at an image-capable objective.
         node_components["objective_target"].configuration.capabilities.input_modalities = frozenset(
             {frozenset({"text"}), frozenset({"text", "image_path"})}
         )
         node_components["objective_target"].configuration.capabilities.output_modalities = frozenset(
             {frozenset({"image_path"})}
         )
+        node_components["objective_target"].configuration.includes.side_effect = lambda capability: (
+            capability == CapabilityName.MULTI_TURN and supports_multi_turn
+        )
         node_components["modality_router"] = _ModalityFeedbackRouter(
             adversarial_chat=node_components["adversarial_chat"],
             objective_target=node_components["objective_target"],