feat(agents,claude_sdk): skill sets per conversation kind

src/beaver_gateway/agents/claude.py

@@ -3,8 +3,10 @@
 The system prompt is ``system_prompt`` verbatim or, per conversation kind,
 the granules named in ``prompts`` assembled at every session spawn (see
 ``core/prompt.py``). ``skill_sets`` are directories of ``<skill>/SKILL.md``
-folders; each becomes a local SDK plugin. Nothing from disk is loaded
-otherwise: the adapter runs with ``setting_sources=[]``.
+folders; each becomes a local SDK plugin, either the same tuple for every
+kind or a ``SkillSets`` with a tuple per kind (§4.3: the master never sees
+what a branch opens). Nothing from disk is loaded otherwise: the adapter
+runs with ``setting_sources=[]``.
 """
 
 from __future__ import annotations
@@ -19,7 +21,7 @@ from beaver_gateway.core.kinds import KINDS, Kind
 from beaver_gateway.core.policy import PolicyRule  # noqa: TC001 - pydantic runtime
 from beaver_gateway.core.prompt import PromptSource  # noqa: TC001 - pydantic runtime
 
-__all__ = ["ClaudeAgent", "ClaudeOptions", "Prompts"]
+__all__ = ["ClaudeAgent", "ClaudeOptions", "Prompts", "SkillSets"]
 
 
 class ClaudeOptions(BaseModel):
@@ -70,6 +72,21 @@ class Prompts(BaseModel):
         return tuple(k for k in KINDS if self.for_kind(k) is not None)
 
 
+class SkillSets(BaseModel):
+    """Skill-set directories per conversation kind; ``None`` means none."""
+
+    model_config = ConfigDict(frozen=True)
+
+    master: tuple[Path, ...] | None = None
+    branch: tuple[Path, ...] | None = None
+    deep: tuple[Path, ...] | None = None
+    job: tuple[Path, ...] | None = None
+    fork: tuple[Path, ...] | None = None
+
+    def for_kind(self, kind: Kind) -> tuple[Path, ...]:
+        return getattr(self, kind) or ()
+
+
 class ClaudeAgent(BaseAgent):
     cwd: Path
     system_prompt: str = ""
@@ -81,7 +98,11 @@ class ClaudeAgent(BaseAgent):
     rest. Defaults to the kinds ``prompts`` covers, or ``("deep",)`` for a
     verbatim ``system_prompt``."""
 
-    skill_sets: tuple[Path, ...] = ()
+    skill_sets: tuple[Path, ...] | SkillSets = ()
+    """Skill-set directories, each a local plugin: one tuple for every kind,
+    or ``SkillSets`` to give each kind its own (a kind left ``None`` gets
+    no skills)."""
+
     gateway_tools: tuple[str, ...] = ()
     """Gateway tools exposed in-process (``read_conversation``, ``spawn``,
     ``say``, ``schedule``, ``inject``); empty = no gateway MCP server."""
@@ -106,5 +127,10 @@ class ClaudeAgent(BaseAgent):
     def prompt_for(self, kind: Kind) -> tuple[PromptSource, ...] | None:
         return self.prompts.for_kind(kind)
 
+    def skills_for(self, kind: Kind) -> tuple[Path, ...]:
+        if isinstance(self.skill_sets, SkillSets):
+            return self.skill_sets.for_kind(kind)
+        return self.skill_sets
+
     def serves(self, kind: str) -> bool:
         return kind in self.kinds