refactor(agent): remove legacy image mode prompt injection

nanobot/agent/tools/image_generation.py

@@ -8,7 +8,6 @@ from typing import TYPE_CHECKING, Any
 from pydantic import Field
 
 from nanobot.agent.tools.base import Tool, ToolResult, tool_parameters
-from nanobot.agent.tools.context import RequestContext
 from nanobot.agent.tools.schema import (
     ArraySchema,
     IntegerSchema,
@@ -22,7 +21,6 @@ from nanobot.providers.image_generation import (
     ImageGenerationProvider,
     get_image_gen_provider,
 )
-from nanobot.runtime_context import RuntimeContextBlock
 from nanobot.security.workspace_access import current_tool_workspace
 from nanobot.security.workspace_policy import WorkspaceBoundaryError, resolve_allowed_path
 from nanobot.utils.artifacts import (
@@ -31,7 +29,6 @@ from nanobot.utils.artifacts import (
     store_generated_image_artifact,
 )
 from nanobot.utils.helpers import detect_image_mime
-from nanobot.utils.image_generation_intent import image_generation_runtime_context
 
 if TYPE_CHECKING:
     from nanobot.config.schema import ProviderConfig
@@ -119,18 +116,6 @@ class ImageGenerationTool(Tool):
             "or user image paths as reference_images."
         )
 
-    def runtime_context_provider(self):
-        return self._provide_runtime_context
-
-    async def _provide_runtime_context(
-        self,
-        request: RequestContext,
-    ) -> RuntimeContextBlock | None:
-        content = image_generation_runtime_context(request.metadata)
-        if not content:
-            return None
-        return RuntimeContextBlock(source="image_generation", content=content)
-
     def _provider_config(self) -> ProviderConfig | None:
         return self.provider_configs.get(self.config.provider)