From dd7db237a50ff753d515876839afc7f90001e5f9 Mon Sep 17 00:00:00 2001
From: Sathvik-1007 <spacetime1007@gmail.com>
Date: Thu, 9 Apr 2026 10:51:38 +0530
Subject: [PATCH] feat(mcp): forward session ID and plugin _meta to MCP tool
 calls

---
 packages/opencode/src/mcp/index.ts      | 4 +++-
 packages/opencode/src/session/prompt.ts | 8 ++++++--
 packages/plugin/src/index.ts            | 2 +-
 3 files changed, 10 insertions(+), 4 deletions(-)

diff --git a/packages/opencode/src/mcp/index.ts b/packages/opencode/src/mcp/index.ts
index 45e3e2567a28..6fd3d48aacf5 100644
--- a/packages/opencode/src/mcp/index.ts
+++ b/packages/opencode/src/mcp/index.ts
@@ -144,11 +144,13 @@ export namespace MCP {
     return dynamicTool({
       description: mcpTool.description ?? "",
       inputSchema: jsonSchema(schema),
-      execute: async (args: unknown) => {
+      execute: async (args: unknown, opts?) => {
+        const meta = (opts as any)?._meta as Record<string, unknown> | undefined
         return client.callTool(
           {
             name: mcpTool.name,
             arguments: (args || {}) as Record<string, unknown>,
+            ...(meta ? { _meta: meta } : {}),
           },
           CallToolResultSchema,
           {
diff --git a/packages/opencode/src/session/prompt.ts b/packages/opencode/src/session/prompt.ts
index e9bd5bcd5605..09fcf684880b 100644
--- a/packages/opencode/src/session/prompt.ts
+++ b/packages/opencode/src/session/prompt.ts
@@ -483,14 +483,18 @@ NOTE: At any point in time through this workflow you should feel free to ask the
             Effect.runPromise(
               Effect.gen(function* () {
                 const ctx = context(args, opts)
+                const hook: { args: unknown; _meta?: Record<string, unknown> } = {
+                  args,
+                  _meta: { sessionID: ctx.sessionID },
+                }
                 yield* plugin.trigger(
                   "tool.execute.before",
                   { tool: key, sessionID: ctx.sessionID, callID: opts.toolCallId },
-                  { args },
+                  hook,
                 )
                 yield* Effect.promise(() => ctx.ask({ permission: key, metadata: {}, patterns: ["*"], always: ["*"] }))
                 const result: Awaited<ReturnType<NonNullable<typeof execute>>> = yield* Effect.promise(() =>
-                  execute(args, opts),
+                  execute(hook.args, { ...opts, _meta: hook._meta } as typeof opts),
                 )
                 yield* plugin.trigger(
                   "tool.execute.after",
diff --git a/packages/plugin/src/index.ts b/packages/plugin/src/index.ts
index 1afb55daa76e..8e71f5ceec49 100644
--- a/packages/plugin/src/index.ts
+++ b/packages/plugin/src/index.ts
@@ -231,7 +231,7 @@ export interface Hooks {
   ) => Promise<void>
   "tool.execute.before"?: (
     input: { tool: string; sessionID: string; callID: string },
-    output: { args: any },
+    output: { args: any; _meta?: Record<string, unknown> },
   ) => Promise<void>
   "shell.env"?: (
     input: { cwd: string; sessionID?: string; callID?: string },