refactor(skills): own explicit runtime context loading

nanobot/agent/context.py

@@ -159,33 +159,6 @@ class ContextBuilder:
 
         return "\n\n---\n\n".join(parts)
 
-    def build_runtime_context_blocks(
-        self,
-        current_message: str,
-        blocks: Sequence[RuntimeContextBlock] | None = None,
-    ) -> list[RuntimeContextBlock]:
-        """Add explicitly invoked skill instructions to this turn's runtime context."""
-        merged = list(blocks or ())
-        invoked = self.skills.get_explicitly_invoked_skills(current_message)
-        if not invoked:
-            return merged
-        always_active = set(self.skills.get_always_skills())
-        skill_names = [name for name in invoked if name not in always_active]
-        skill_content = self.skills.load_skills_for_context(skill_names)
-        if not skill_content:
-            return merged
-        skill_block = RuntimeContextBlock(
-            source="explicit_skills",
-            content=(
-                "[Active Skills — instructions for this user turn]\n"
-                f"{skill_content}\n"
-                "[/Active Skills]"
-            ),
-        )
-        if skill_block not in merged:
-            merged.append(skill_block)
-        return merged
-
     @staticmethod
     def _without_duplicate_session_summary(
         entries: list[dict[str, Any]],
@@ -347,11 +320,12 @@ class ContextBuilder:
     ) -> dict[str, Any]:
         """Build only the fresh turn message without merging it into history."""
         content = self.build_user_content(current_message, image_paths=media)
-        blocks = (
-            self.build_runtime_context_blocks(current_message, runtime_context_blocks)
-            if current_role == "user"
-            else []
-        )
+        blocks: list[RuntimeContextBlock] = []
+        if current_role == "user":
+            blocks.extend(runtime_context_blocks or ())
+            skill_context = self.skills.build_explicit_skill_runtime_context(current_message)
+            if skill_context is not None and skill_context not in blocks:
+                blocks.append(skill_context)
         merged, runtime_context_meta = append_runtime_context(content, blocks)
         current: dict[str, Any] = {"role": current_role, "content": merged}
         if current_role == "user" and runtime_context_meta is not None:

nanobot/agent/loop.py

@@ -797,10 +797,12 @@ class AgentLoop:
         ]
         blocks = runtime_context_blocks_from_metadata(request.metadata)
         blocks.extend(await resolve_runtime_context(providers, request))
-        return self.context.build_runtime_context_blocks(
-            request.original_user_text or "",
-            blocks,
+        skill_context = self.context.skills.build_explicit_skill_runtime_context(
+            request.original_user_text or ""
         )
+        if skill_context is not None and skill_context not in blocks:
+            blocks.append(skill_context)
+        return blocks
 
     async def _dispatch_command_inline(
         self,

nanobot/agent/skills.py

@@ -9,6 +9,8 @@ from typing import Any, cast
 
 import yaml
 
+from nanobot.runtime_context import RuntimeContextBlock
+
 # Default builtin skills directory (relative to this file)
 BUILTIN_SKILLS_DIR = Path(__file__).parent.parent / "skills"
 
@@ -177,6 +179,28 @@ class SkillsLoader:
                 invoked.append(name)
         return invoked
 
+    def build_explicit_skill_runtime_context(
+        self,
+        text: str,
+    ) -> RuntimeContextBlock | None:
+        """Load non-always skills explicitly invoked by the current message."""
+        skill_names = self.get_explicitly_invoked_skills(text)
+        if not skill_names:
+            return None
+        always_active = set(self.get_always_skills())
+        skill_names = [name for name in skill_names if name not in always_active]
+        content = self.load_skills_for_context(skill_names)
+        if not content:
+            return None
+        return RuntimeContextBlock(
+            source="explicit_skills",
+            content=(
+                "[Active Skills — instructions for this user turn]\n"
+                f"{content}\n"
+                "[/Active Skills]"
+            ),
+        )
+
     def build_skills_summary(self, exclude: set[str] | None = None) -> str:
         """
         Build a summary of all skills (name, description, path, availability).