feat(opencode): add plan mode, reasoning effort, and status telemetry (#688)

* feat(opencode): support plan mode

* feat(opencode): support reasoning effort

* feat(opencode): surface context usage in web

Bridge OpenCode ACP usage updates into the existing token-count pipeline so the web status bar can show live context and cache information without a separate UI path.

Co-authored-by: Cursor <cursoragent@cursor.com>

* fix(opencode): restrict plan mode to remote, rollback reasoning effort on failure

- Block local OpenCode plan startup (tools not enforced in local path)
- Allow remote OpenCode plan only (ACP permission handler denies tools)
- Guard web /permission-mode endpoint for local OpenCode plan sessions
- Rollback session reasoning effort when OpenCode rejects set_config_option
- Wire rollback callback through opencodeLoop to runOpencode closure
- Add tests: local plan rejected, remote plan allowed, web guard, effort rollback

* fix(web): auto-retry OpenCode models query to populate model selector without refresh

- Retry early failures (RPC may still be registering on new sessions)
- Poll briefly until availableModels is non-empty
- Stop polling once model options are discovered
- Add tests for retry/poll/stop policy

* fix(opencode): cap model discovery polling

---------

Co-authored-by: Cursor <cursoragent@cursor.com>

cli/src/runner/run.ts

@@ -933,7 +933,7 @@ export function buildCliArgs(
   if (options.effort && agent === 'claude') {
     args.push('--effort', options.effort);
   }
-  if (options.modelReasoningEffort && agent === 'codex') {
+  if (options.modelReasoningEffort && (agent === 'codex' || agent === 'opencode')) {
     args.push('--model-reasoning-effort', options.modelReasoningEffort);
   }
   if (options.permissionMode && (PERMISSION_MODES as readonly string[]).includes(options.permissionMode)) {