Web UI: client-generated message IDs cause infinite processing loop when client/server clocks diverge

[KONFeature]

Description

When sending a message from the Web UI, the user message gets an ID that sorts after all assistant message IDs, causing the processing loop in prompt.ts to never exit.

This burns tokens indefinitely in the background, and it also prevent Web UI (or desktop UI I assume), to display the right message. On the TUI side, the user message is marked as queued.

Root cause:
The Web UI generates messageID client-side (packages/app/src/utils/id.ts) before sending to the backend, while assistant message IDs are generated server-side (packages/opencode/src/id/id.ts).

Both use the same algorithm, but any clock skew between client and server means the user message ID sorts after (or before) assistant IDs, breaking the assumption that ID order = chronological order.

The loop exit condition at session/prompt.ts L296-303 checks lastUser.id < lastAssistant.id — if the user ID is "larger" (client clock ahead), the loop never breaks and keeps generating responses indefinitely.

Observed data (from the session messages endpoint, see attached JSON):

#	Role	ID	time.created
1	assistant	msg_c1f6b1d57001RHuvN3zOJhP9vQ	1770053639511
2	assistant	msg_c1f6b7956001ie0EeKm2LsYp68	1770053663062
3	assistant	msg_c1f71ddc4001pBbmRnquIAmNbi	1770054081988
4	user	msg_c20455b9d001RX64FkeGhqcCIC	1770053639500

The user message was created 11ms before the first assistant message (time.created: 1770053639500 vs 1770053639511), yet its ID timestamp hex (c20455b9d001) sorts after all assistant ID prefixes (c1f6..., c1f7...). The assistant messages reference the user message as parentID, confirming it's the original prompt.

session-output.json

This causes the loop to see lastUser.id > lastAssistant.id → condition to exit is never met → infinite response generation.

Potentially related to #7426 (message ordering issues with ID-based sorting).

Plugins

none

OpenCode version

1.1.48

Steps to reproduce

1. Start OpenCode with Web UI on a remote server (where client and server clocks may differ)
2. Send a message from the Web UI
3. Observe: assistant responds, then immediately starts processing again
4. Tokens burn continuously until manually stopped via TUI

Screenshot and/or share link

No response

Operating System

No response

Terminal

No response

[github-actions]

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

• opencode export outputs messages in wrong order for long sessions #7426: Message ordering issues with ID-based sorting - the root cause of both issues stems from ID-based chronological assumptions

This issue appears to be related to #7426 as it also involves incorrect message ordering due to ID sorting. In #7426, messages are exported in the wrong order because alphabetical ID sorting doesn't guarantee chronological order. In this issue (#11863), the loop exit condition relies on ID comparison assuming ID order correlates to message creation time, which breaks when client/server clocks diverge.

Both issues highlight the same architectural assumption: that message ID string comparison reflects chronological order. The fix for one should likely address concerns in both.