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

packages/core/src/tool/mcp.ts

@@ -0,0 +1,101 @@
+export * as McpTool from "./mcp"
+
+import { createHash } from "node:crypto"
+import { ToolFailure } from "@opencode-ai/llm"
+import { McpEvent } from "@opencode-ai/schema/mcp-event"
+import { Effect, Exit, type JsonSchema, Layer, Scope, Semaphore, Stream } from "effect"
+import { makeLocationNode } from "../effect/app-node"
+import { EventV2 } from "../event"
+import { MCP } from "../mcp"
+import { Tool } from "./tool"
+import { Tools } from "./tools"
+import { ToolRegistry } from "./registry"
+
+const MAX_NAME_LENGTH = 64
+const HASH_LENGTH = 8
+
+const sanitize = (value: string) => value.replace(/[^A-Za-z0-9_-]/g, "_")
+
+// Deterministic short suffix used to keep overlong or colliding names unique and stable across restarts.
+const hashSuffix = (raw: string) => "_" + createHash("sha1").update(raw).digest("hex").slice(0, HASH_LENGTH)
+
+const fit = (base: string, raw: string) => base.slice(0, MAX_NAME_LENGTH - HASH_LENGTH - 1) + hashSuffix(raw)
+
+/**
+ * Registry/permission action name for an MCP tool: V1-compatible `<server>_<tool>` so existing deny
+ * rules keep working. Sanitized to a valid tool name, prefixed when it would not start with a letter,
+ * and hashed down when it would exceed the 64-char limit.
+ */
+export const name = (server: string, tool: string) => {
+  const joined = sanitize(server) + "_" + sanitize(tool)
+  const base = /^[A-Za-z]/.test(joined) ? joined : "mcp_" + joined
+  return base.length > MAX_NAME_LENGTH ? fit(base, `${server}\u0000${tool}`) : base
+}
+
+const toContent = (part: MCP.ToolResultContent): Tool.Content =>
+  part.type === "text" ? { type: "text", text: part.text } : { type: "file", data: part.data, mime: part.mimeType }
+
+const errorText = (content: ReadonlyArray<MCP.ToolResultContent>) =>
+  content
+    .flatMap((part) => (part.type === "text" ? [part.text] : []))
+    .join("\n")
+    .trim()
+
+export const layer = Layer.effectDiscard(
+  Effect.gen(function* () {
+    const mcp = yield* MCP.Service
+    const tools = yield* Tools.Service
+    const events = yield* EventV2.Service
+    const scope = yield* Scope.Scope
+    const lock = Semaphore.makeUnsafe(1)
+    let current: Scope.Closeable | undefined
+
+    const make = (server: MCP.ServerName, tool: MCP.Tool) =>
+      Tool.make({
+        description: tool.description ?? "",
+        jsonSchema: (tool.inputSchema as JsonSchema.JsonSchema | undefined) ?? { type: "object", properties: {} },
+        execute: (input) =>
+          Effect.gen(function* () {
+            const result = yield* mcp.callTool({ server, name: tool.name, args: (input ?? {}) as Record<string, unknown> }).pipe(
+              Effect.catchTags({
+                "MCP.NotFoundError": (error) => new ToolFailure({ message: `MCP server "${error.server}" is not available` }),
+                "MCP.ToolCallError": (error) => new ToolFailure({ message: error.message }),
+              }),
+            )
+            if (result.isError)
+              return yield* new ToolFailure({ message: errorText(result.content) || "MCP tool returned an error" })
+            return { structured: result.structured ?? {}, content: result.content.map(toContent) }
+          }),
+      })
+
+    // Register the current tool set under a fresh child scope, then close the previous one so the
+    // registry never has a gap where MCP tools disappear mid-swap.
+    const reconcile = lock.withPermit(
+      Effect.gen(function* () {
+        const used = new Set<string>()
+        const record: Record<string, Tool.AnyTool> = {}
+        for (const tool of yield* mcp.tools()) {
+          const initial = name(tool.server, tool.name)
+          const key = used.has(initial) ? fit(initial, `${tool.server}\u0000${tool.name}`) : initial
+          used.add(key)
+          record[key] = make(tool.server, tool)
+        }
+        const next = yield* Scope.fork(scope)
+        yield* tools.register(record).pipe(Scope.provide(next), Effect.orDie)
+        if (current) yield* Scope.close(current, Exit.void)
+        current = next
+      }),
+    )
+
+    yield* reconcile.pipe(Effect.forkScoped)
+    yield* events
+      .subscribe(McpEvent.ToolsChanged)
+      .pipe(Stream.runForEach(() => reconcile), Effect.forkScoped({ startImmediately: true }))
+  }),
+)
+
+export const node = makeLocationNode({
+  name: "mcp-tools",
+  layer,
+  deps: [ToolRegistry.toolsNode, MCP.node, EventV2.node],
+})