fix: actually modify opencode config with mcp add (#7339)

packages/opencode/src/cli/cmd/mcp.ts

@@ -1,7 +1,6 @@
 import { cmd } from "./cmd"
 import { Client } from "@modelcontextprotocol/sdk/client/index.js"
 import { StreamableHTTPClientTransport } from "@modelcontextprotocol/sdk/client/streamableHttp.js"
-import { SSEClientTransport } from "@modelcontextprotocol/sdk/client/sse.js"
 import { UnauthorizedError } from "@modelcontextprotocol/sdk/client/auth.js"
 import * as prompts from "@clack/prompts"
 import { UI } from "../ui"
@@ -13,6 +12,7 @@ import { Instance } from "../../project/instance"
 import { Installation } from "../../installation"
 import path from "path"
 import { Global } from "../../global"
+import { modify, applyEdits } from "jsonc-parser"
 
 function getAuthStatusIcon(status: MCP.AuthStatus): string {
   switch (status) {
@@ -366,13 +366,83 @@ export const McpLogoutCommand = cmd({
   },
 })
 
+async function resolveConfigPath(baseDir: string, global = false) {
+  // Check for existing config files (prefer .jsonc over .json, check .opencode/ subdirectory too)
+  const candidates = [path.join(baseDir, "opencode.json"), path.join(baseDir, "opencode.jsonc")]
+
+  if (!global) {
+    candidates.push(path.join(baseDir, ".opencode", "opencode.json"), path.join(baseDir, ".opencode", "opencode.jsonc"))
+  }
+
+  for (const candidate of candidates) {
+    if (await Bun.file(candidate).exists()) {
+      return candidate
+    }
+  }
+
+  // Default to opencode.json if none exist
+  return candidates[0]
+}
+
+async function addMcpToConfig(name: string, mcpConfig: Config.Mcp, configPath: string) {
+  const file = Bun.file(configPath)
+
+  let text = "{}"
+  if (await file.exists()) {
+    text = await file.text()
+  }
+
+  // Use jsonc-parser to modify while preserving comments
+  const edits = modify(text, ["mcp", name], mcpConfig, {
+    formattingOptions: { tabSize: 2, insertSpaces: true },
+  })
+  const result = applyEdits(text, edits)
+
+  await Bun.write(configPath, result)
+
+  return configPath
+}
+
 export const McpAddCommand = cmd({
   command: "add",
   describe: "add an MCP server",
   async handler() {
+    await Instance.provide({
+      directory: process.cwd(),
+      async fn() {
         UI.empty()
         prompts.intro("Add MCP server")
 
+        const project = Instance.project
+
+        // Resolve config paths eagerly for hints
+        const [projectConfigPath, globalConfigPath] = await Promise.all([
+          resolveConfigPath(Instance.worktree),
+          resolveConfigPath(Global.Path.config, true),
+        ])
+
+        // Determine scope
+        let configPath = globalConfigPath
+        if (project.vcs === "git") {
+          const scopeResult = await prompts.select({
+            message: "Location",
+            options: [
+              {
+                label: "Current project",
+                value: projectConfigPath,
+                hint: projectConfigPath,
+              },
+              {
+                label: "Global",
+                value: globalConfigPath,
+                hint: globalConfigPath,
+              },
+            ],
+          })
+          if (prompts.isCancel(scopeResult)) throw new UI.CancelledError()
+          configPath = scopeResult
+        }
+
         const name = await prompts.text({
           message: "Enter MCP server name",
           validate: (x) => (x && x.length > 0 ? undefined : "Required"),
@@ -404,7 +474,13 @@ export const McpAddCommand = cmd({
           })
           if (prompts.isCancel(command)) throw new UI.CancelledError()
 
-      prompts.log.info(`Local MCP server "${name}" configured with command: ${command}`)
+          const mcpConfig: Config.Mcp = {
+            type: "local",
+            command: command.split(" "),
+          }
+
+          await addMcpToConfig(name, mcpConfig, configPath)
+          prompts.log.success(`MCP server "${name}" added to ${configPath}`)
           prompts.outro("MCP server added successfully")
           return
         }
@@ -428,6 +504,8 @@ export const McpAddCommand = cmd({
           })
           if (prompts.isCancel(useOAuth)) throw new UI.CancelledError()
 
+          let mcpConfig: Config.Mcp
+
           if (useOAuth) {
             const hasClientId = await prompts.confirm({
               message: "Do you have a pre-registered client ID?",
@@ -457,44 +535,37 @@ export const McpAddCommand = cmd({
                 clientSecret = secret
               }
 
-          prompts.log.info(`Remote MCP server "${name}" configured with OAuth (client ID: ${clientId})`)
+              mcpConfig = {
-          prompts.log.info("Add this to your opencode.json:")
+                type: "remote",
-          prompts.log.info(`
+                url,
-  "mcp": {
+                oauth: {
-    "${name}": {
+                  clientId,
-      "type": "remote",
+                  ...(clientSecret && { clientSecret }),
-      "url": "${url}",
+                },
-      "oauth": {
-        "clientId": "${clientId}"${clientSecret ? `,\n        "clientSecret": "${clientSecret}"` : ""}
-      }
-    }
-  }`)
-        } else {
-          prompts.log.info(`Remote MCP server "${name}" configured with OAuth (dynamic registration)`)
-          prompts.log.info("Add this to your opencode.json:")
-          prompts.log.info(`
-  "mcp": {
-    "${name}": {
-      "type": "remote",
-      "url": "${url}",
-      "oauth": {}
-    }
-  }`)
               }
             } else {
-        const client = new Client({
+              mcpConfig = {
-          name: "opencode",
+                type: "remote",
-          version: "1.0.0",
+                url,
-        })
+                oauth: {},
-        const transport = new StreamableHTTPClientTransport(new URL(url))
+              }
-        await client.connect(transport)
+            }
-        prompts.log.info(`Remote MCP server "${name}" configured with URL: ${url}`)
+          } else {
+            mcpConfig = {
+              type: "remote",
+              url,
             }
           }
 
+          await addMcpToConfig(name, mcpConfig, configPath)
+          prompts.log.success(`MCP server "${name}" added to ${configPath}`)
+        }
+
         prompts.outro("MCP server added successfully")
       },
     })
+  },
+})
 
 export const McpDebugCommand = cmd({
   command: "debug <name>",