Plugin events miss session.created for sessions resumed via --session flag

When OpenCode is launched with --session <id> (or -s <id>) to resume an existing session from disk, the plugin lifecycle hooks never receive any event for that session. Plugins cannot detect the pane-to-session binding.

For sessions started fresh (opencode with no flags), session.created is emitted normally with the session id in the payload.

This is reproducible without any external dependencies — a 10-line plugin shows the issue.

Steps to reproduce

1. Save this plugin to ~/.config/opencode/plugins/debug-session-events.js:

   import fs from "node:fs";
   const LOG = "/tmp/opencode-session-debug.log";
   export const DebugSessionEvents = async () => {
     const append = (line) => {
       try { fs.appendFileSync(LOG, `[${new Date().toISOString()}] ${line}\n`); } catch {}
     };
     fs.writeFileSync(LOG, "");
     append("plugin loaded");
     return {
       event: async ({ event }) => {
         append(`event: type=${event?.type} sessionID=${event?.properties?.sessionID ?? "(none)"}`);
       },
     };
   };
   

2. Start a fresh session:

   rm /tmp/opencode-session-debug.log
   opencode
   

   Send one message, then quit. cat /tmp/opencode-session-debug.log shows session.created with the session id.

3. Resume the same session:

   rm /tmp/opencode-session-debug.log
   opencode -s <id_from_step_2>
   

   Wait 5s, send one message, quit. cat /tmp/opencode-session-debug.log shows no session.created. A session.updated eventually fires but only after the first user message — it does not fire at startup.

Expected

Either:

• session.created should fire at startup when a session is loaded from disk via -s/--session, OR
• a new event like session.attached should fire with the session id.

Actual

No event with the session id fires at startup for resumed sessions. The plugin only learns about the session after the first user message (and even then, the sessionID is sometimes missing from the payload — race condition between plugin init and OpenCode startup).

Environment

• OpenCode version: 1.18.10
• OS: Linux 6.14.0-37-generic
• Terminal: xterm-256color

Notes

Affected downstream: the herdr-agent-state integration plugin (v9) cannot detect resumed sessions because of this, leaving pane→session bindings missing in external tools. PR herdrdev/herdr#2062 attempted an argv-parsing workaround, but process.argv inside the bundled Bun runtime is ["bun", "/$bunfs/root/src/cli/tui/worker.js"] — the user-supplied -s <id> is not visible to the plugin.