feat(opencode): add OPENCODE_APP_URL for custom web app proxy

Add environment variable to proxy the web UI to a custom URL instead of
app.opencode.ai. This enables enterprises to host the web UI internally
and have users run the local server pointing to the internal instance.

Author: Josh Brooks

packages/opencode/src/flag/flag.ts

@@ -31,6 +31,7 @@ export namespace Flag {
   export const OPENCODE_SERVER_PASSWORD = process.env["OPENCODE_SERVER_PASSWORD"]
   export const OPENCODE_SERVER_USERNAME = process.env["OPENCODE_SERVER_USERNAME"]
   export const OPENCODE_ENABLE_QUESTION_TOOL = truthy("OPENCODE_ENABLE_QUESTION_TOOL")
+  export const OPENCODE_APP_URL = process.env["OPENCODE_APP_URL"]
 
   // Experimental
   export const OPENCODE_EXPERIMENTAL = truthy("OPENCODE_EXPERIMENTAL")

packages/opencode/src/server/server.ts

@@ -543,11 +543,13 @@ export namespace Server {
         .all("/*", async (c) => {
           const path = c.req.path
 
-          const response = await proxy(`https://app.opencode.ai${path}`, {
+          // Proxy to configured app URL or default to app.opencode.ai
+          const appUrl = Flag.OPENCODE_APP_URL ? new URL(Flag.OPENCODE_APP_URL) : new URL("https://app.opencode.ai")
+          const response = await proxy(`${appUrl.origin}${path}`, {
             ...c.req,
             headers: {
               ...c.req.raw.headers,
-              host: "app.opencode.ai",
+              host: appUrl.host,
             },
           })
           response.headers.set(