feat(core): add mcp support (#34513)

packages/core/src/session/runner/llm.ts

@@ -20,6 +20,7 @@ import { SystemContext } from "../../system-context/index"
 import { SystemContextRegistry } from "../../system-context/registry"
 import { SkillGuidance } from "../../skill/guidance"
 import { ReferenceGuidance } from "../../reference/guidance"
+import { McpGuidance } from "../../mcp/guidance"
 import { ToolRegistry } from "../../tool/registry"
 import { ToolOutputStore } from "../../tool-output-store"
 import { SessionContextEpoch } from "../context-epoch"
@@ -102,6 +103,7 @@ export const layer = Layer.effect(
     const systemContext = yield* SystemContextRegistry.Service
     const skillGuidance = yield* SkillGuidance.Service
     const referenceGuidance = yield* ReferenceGuidance.Service
+    const mcpGuidance = yield* McpGuidance.Service
     const snapshots = yield* Snapshot.Service
     const db = (yield* Database.Service).db
     const compaction = yield* SessionCompaction.Service
@@ -160,7 +162,7 @@ export const layer = Layer.effect(
       new TurnTransitionError({ _tag: "ContinueAfterOverflowCompaction", step })
 
     const loadSystemContext = (agent: AgentV2.Selection) =>
-      Effect.all([systemContext.load(), skillGuidance.load(agent), referenceGuidance.load()], {
+      Effect.all([systemContext.load(), skillGuidance.load(agent), referenceGuidance.load(), mcpGuidance.load(agent)], {
         concurrency: "unbounded",
       }).pipe(Effect.map(SystemContext.combine))
 
@@ -424,6 +426,7 @@ export const node = makeLocationNode({
     SystemContextRegistry.node,
     SkillGuidance.node,
     ReferenceGuidance.node,
+    McpGuidance.node,
     SessionCompaction.node,
     Snapshot.node,
     Database.node,