[Fix] Agents identify as OpenCode before Roomote

apps/worker/src/run-task/agent-home.ts

@@ -5,6 +5,7 @@ import * as path from 'node:path';
 import {
   createRoomoteAdvisorAgentPrompt,
   createRoomoteJudgeAgentPrompt,
+  OPENCODE_IDENTITY_PLUGIN_SCRIPT,
   ROOMOTE_OPENCODE_ADVISOR_AGENT_DESCRIPTION,
   ROOMOTE_OPENCODE_ADVISOR_AGENT_NAME,
   ROOMOTE_OPENCODE_JUDGE_AGENT_DESCRIPTION,
@@ -180,6 +181,8 @@ const ROOMOTE_OPENCODE_CHATGPT_GATEWAY_PLUGIN_FILE_NAME =
 
 const ROOMOTE_OPENCODE_TOOL_SAFETY_PLUGIN_FILE_NAME = 'roomote-tool-safety.js';
 
+const ROOMOTE_OPENCODE_IDENTITY_PLUGIN_FILE_NAME = 'roomote-identity.js';
+
 const OPENCODE_ALLOW_ALL_PERMISSION = {
   read: 'allow',
   edit: 'allow',
@@ -653,6 +656,10 @@ function writeOpenCodeManagedFiles(openCodeConfigDir: string): void {
     pluginsDir,
     ROOMOTE_OPENCODE_TOOL_SAFETY_PLUGIN_FILE_NAME,
   );
+  const identityPluginPath = path.join(
+    pluginsDir,
+    ROOMOTE_OPENCODE_IDENTITY_PLUGIN_FILE_NAME,
+  );
   const silenceHookPath = path.join(
     openCodeConfigDir,
     ROOMOTE_OPENCODE_SLACK_SILENCE_HOOK_FILE_NAME,
@@ -674,6 +681,7 @@ function writeOpenCodeManagedFiles(openCodeConfigDir: string): void {
     OPENCODE_TOOL_SAFETY_PLUGIN_SCRIPT,
     'utf8',
   );
+  fs.writeFileSync(identityPluginPath, OPENCODE_IDENTITY_PLUGIN_SCRIPT, 'utf8');
   fs.writeFileSync(silenceHookPath, SLACK_SILENCE_HOOK_SCRIPT, 'utf8');
   fs.writeFileSync(stopHookPath, SLACK_STOP_HOOK_SCRIPT, 'utf8');
   fs.chmodSync(silenceHookPath, 0o755);

packages/cloud-agents/src/index.ts

@@ -16,6 +16,7 @@ export {
 export { resolveRoomoteReleaseVersion } from './release-version';
 export * from './style-guidance';
 export * from './opencode-prompt-subagents';
+export { OPENCODE_IDENTITY_PLUGIN_SCRIPT } from './opencode-identity-plugin';
 export {
   DEFAULT_STANDARD_TASK_MODEL,
   DEFAULT_STANDARD_TASK_MODEL_PROVIDER,

packages/cloud-agents/src/opencode-identity-plugin.ts

@@ -0,0 +1,13 @@
+/**
+ * OpenCode 1.18.10 prefixes its model-specific system prompt with its own
+ * product identity. Roomote supplies the product identity in later prompt
+ * layers, so remove only that prefix and preserve the remaining instructions.
+ */
+export const OPENCODE_IDENTITY_PLUGIN_SCRIPT = `export const RoomoteOpenCodeIdentity = async () => ({
+  'experimental.chat.system.transform': async (_input, output) => {
+    if (typeof output.system?.[0] === 'string') {
+      output.system[0] = output.system[0].replace(/^You are OpenCode,\\s*/iu, '');
+    }
+  },
+});
+`;

packages/cloud-agents/src/server/opencode-runtime.ts

@@ -1,6 +1,10 @@
 import { execFileSync, spawn, type ChildProcess } from 'node:child_process';
 import { createHash } from 'node:crypto';
+import { mkdtempSync, writeFileSync } from 'node:fs';
 import { createServer } from 'node:net';
+import { tmpdir } from 'node:os';
+import { join } from 'node:path';
+import { pathToFileURL } from 'node:url';
 
 import {
   collectOpenRouterVariantModelAlias,
@@ -28,6 +32,7 @@ import {
   ROOMOTE_OPENCODE_JUDGE_AGENT_DESCRIPTION,
   ROOMOTE_OPENCODE_JUDGE_AGENT_NAME,
 } from '../opencode-prompt-subagents';
+import { OPENCODE_IDENTITY_PLUGIN_SCRIPT } from '../opencode-identity-plugin';
 import { FAST_AGENT_SUBAGENT_TOOL_FILTER } from './fast-agent/fast-agent-tool-policy';
 
 const ESCAPE_CHARACTER = String.fromCharCode(27);
@@ -221,6 +226,23 @@ type NonTaskOpenCodeRuntimeOptions = {
   promptOnlySubagents?: boolean;
 };
 
+let openCodeIdentityPluginUrl: string | undefined;
+
+function getOpenCodeIdentityPluginUrl(): string {
+  if (openCodeIdentityPluginUrl) {
+    return openCodeIdentityPluginUrl;
+  }
+
+  const directory = mkdtempSync(join(tmpdir(), 'roomote-opencode-identity-'));
+  const pluginPath = join(directory, 'roomote-identity.mjs');
+  writeFileSync(pluginPath, OPENCODE_IDENTITY_PLUGIN_SCRIPT, {
+    encoding: 'utf8',
+    mode: 0o600,
+  });
+  openCodeIdentityPluginUrl = pathToFileURL(pluginPath).href;
+  return openCodeIdentityPluginUrl;
+}
+
 function buildRestrictedNonTaskConfig(
   options: NonTaskOpenCodeRuntimeOptions,
 ): Record<string, unknown> {
@@ -230,6 +252,7 @@ function buildRestrictedNonTaskConfig(
 
   return {
     agent: PROMPT_ONLY_SUBAGENTS,
+    plugin: [getOpenCodeIdentityPluginUrl()],
     permission: { ...NON_TASK_TOOL_PERMISSION_DENIALS, task: 'allow' },
   };
 }