Description

Under certain conditions, opencode sessions fail to terminate correctly, causing the assistant to continuously create new messages in an infinite loop, even when the model has returned a finish=stop status.

Plugins

No response

OpenCode version

1.2.1

Steps to reproduce

Bug Report: Session Loop Termination Condition Fails Causing Infinite Loop

Summary

Under certain conditions, opencode sessions fail to terminate correctly, causing the assistant to continuously create new messages in an infinite loop, even when the model has returned a finish=stop status.

Environment

• opencode version: 1.2.1
• Model: glm-5
• OS: Linux
• Session ID: ses_3a477417effeooCd5Cq2mJV3lE

Problem Description

After executing a security analysis task, the model returned finish=stop multiple times, but the system did not correctly terminate the loop. Instead, it continued creating new assistant messages, eventually producing 96 messages until the user manually aborted.

Key Metrics

Root Cause Analysis

The issue is in the loop termination condition at lines 263-271 of packages/opencode/src/session/prompt.ts:

if (
  lastAssistant?.finish &&
  !["tool-calls", "unknown"].includes(lastAssistant.finish) &&
  lastUser.id < lastAssistant.id
) {
  log.info("exiting loop", { sessionID })
  break
}

The Problem

The condition lastUser.id < lastAssistant.id uses string comparison to determine message ordering.

Actual message IDs:

• User message: msg_e6f0bd865e63
• Assistant message: msg_c5b88be94001tLa8xeuxsiub6h

String comparison:

• msg_e... vs msg_c...
• Second character: e (ASCII 101) vs c (ASCII 99)
• Result: "e" > "c" → lastUser.id < lastAssistant.id = false

Loop Flow

while (true) {
  1. Get message stream
  2. lastUser = first user message (msg_e6f0bd865e63)
  3. lastAssistant = last assistant message (finish=stop)
  4. Check termination: lastUser.id < lastAssistant.id → false
  5. Condition not met, continue loop
  6. Create new assistant message
  7. Model returns finish=stop
  8. Back to step 1... (infinite loop)
}

Steps to Reproduce

1. Start opencode serve
2. Send a complex task that triggers multiple tool calls (e.g., using a skill for security analysis)
3. After task completion, model returns finish=stop
4. Observe whether the session terminates correctly

Expected Behavior

When the model returns finish=stop, the session should correctly terminate the loop and stop creating new assistant messages.

Actual Behavior

The session continues creating new assistant messages in an infinite loop until:

• User manually aborts
• Or another error is triggered

Impact

1. Resource consumption: CPU, memory, and API calls continuously grow
2. Cost increase: Unnecessary model API calls
3. User experience: Session hangs and cannot end normally

Suggested Fixes

Option 1: Remove ID Comparison (Recommended)

Since the finish status already indicates the model has completed:

if (
  lastAssistant?.finish &&
  !["tool-calls", "unknown"].includes(lastAssistant.finish)
) {
  log.info("exiting loop", { sessionID })
  break
}

Option 2: Use Timestamp Comparison

if (
  lastAssistant?.finish &&
  !["tool-calls", "unknown"].includes(lastAssistant.finish) &&
  lastUser.time.created < lastAssistant.time.created
) {
  log.info("exiting loop", { sessionID })
  break
}

Option 3: Ensure IDs are Comparable

If ID comparison is necessary, ensure the ID generation strategy produces lexicographically correct identifiers (e.g., using timestamp prefixes).

Relevant Logs

INFO  session.prompt step=0 sessionID=ses_3a477417effeooCd5Cq2mJV3lE loop
INFO  session.prompt step=1 sessionID=ses_3a477417effeooCd5Cq2mJV3lE loop
...
INFO  session.prompt step=88 sessionID=ses_3a477417effeooCd5Cq2mJV3lE loop
// "exiting loop" log never appears

Database Verification

-- Verify message IDs and finish status
SELECT id, json_extract(data, '$.role'), json_extract(data, '$.finish') 
FROM message 
WHERE session_id='ses_3a477417effeooCd5Cq2mJV3lE' 
ORDER BY time_created;

-- Results show:
-- User message ID: msg_e6f0bd865e63 (finish: null)
-- Assistant message ID: msg_c5b88be94001tLa8xeuxsiub6h (finish: stop)
-- String comparison: "e" > "c", causing the condition to always be false

Related Files

• packages/opencode/src/session/prompt.ts - Loop termination logic
• packages/opencode/src/session/processor.ts - Finish status setting
• packages/opencode/src/id/id.ts - ID generation strategy

Report Date: 2026-02-14
Reporter: opencode user fsdgGFF

Screenshot and/or share link

No response

Operating System

linux

Terminal

No response