fix: non-interactive exits before stream completes — only emitted

[hardes11]

Bug Description

In non-interactive mode (opencode run "..." --format json), the event processing loop is started with fire-and-forget, causing the process to exit before the model finishes generating — only the step_start event is emitted, all text, tool_use, and step_finish events are lost.

Steps to Reproduce

# 1. Run a simple query with --format json
$ opencode run "what is 2+2? reply with just the number" \
    --format json \
    --dangerously-skip-permissions

# 2. Observe: only `step_start` is emitted, then the process exits
{"type":"step_start",...}

# Expected: `step_start`, `text` (with answer), `step_finish`
{"type":"step_start",...}
{"type":"text","part":{"type":"text","text":"4",...}}
{"type":"step_finish","part":{"reason":"stop","tokens":{...},...}}

Root Cause

In packages/opencode/src/cli/cmd/run.ts, the non-interactive path in execute():

const events = await client.event.subscribe()
loop(client, events).catch((e) => { console.error(e); process.exit(1) })  // fire-and-forget
const result = await client.session.prompt({...})  // returns HTTP ack
// execute() returns → finally block disposes in-process server → SSE killed

When prompt() returns the HTTP acknowledgment, execute() returns. The Effect framework's cleanup (effect-cmd.ts) then disposes the in-process server, killing the SSE stream before the model finishes generating.

Only step_start is emitted (it arrives before prompt() returns). All other events are lost.

Fix

Store the loop promise and await it after the prompt/command call completes:

const loopDone = loop(client, events)

// ... prompt or command call ...

try {
  const loopError = await loopDone
  if (loopError) process.exitCode = 1
} catch (e) {
  console.error(e)
  process.exitCode = 1
}

This keeps the process alive until the session reaches idle and all events are processed.

Testing

• Before fix: only step_start (1 line of JSON)
• After fix: step_start, text, step_finish (3 lines)
• Confirmed with DeepSeek API and Tavily web search tool outputs

Impact

This breaks any automated tool or CI pipeline relying on opencode run --format json for structured output capture (web search results, reasoning content, tool use events).

[github-actions]

This issue might be a duplicate of existing issues. Please check:

• run --format json can exit before emitting final step_finish event #26855: Same root cause — opencode run --format json exits before all events are emitted, specifically step_finish can be lost due to the SSE loop race with process teardown

[hardes11]

Duplicate of #26855 — same root cause (SSE loop race with process teardown). This issue includes a proposed fix in PR #29132.