[Bug]: Prometheus(Claude model) consulting Momus mostly results in "tool_use ids were found without tool_result blocks" error

[zephy358]

Prerequisites

• I will write this issue in English (see our Language Policy)
• I have searched existing issues to avoid duplicates
• I am using the latest version of oh-my-opencode
• I have read the documentation or asked an AI coding agent with this project's GitHub URL loaded and couldn't find the answer

Bug Description

Mostly this is cuased by a interleaved tool call. Related issue

Basically, Prometheus reads plan, consults Momus, and then modify plan will trigger "should read before write" error because there's a momus feedback message in between tool calls.

Although this is a opencode bug. I was wondering if omo can do something on your side?

Steps to Reproduce

1. Ask Prometheus to continue planning a plan file that is interrupted somehow.
2. Allows Promethus to consult Momus.
3. After Momus feedback, Prometheus starts modify, opencode shows "should read before write error", then this bug occurs and session cannot continue. Undo doesn't help as long as it consults Momus.

Expected Behavior

"tool_use ids were found without tool_result blocks" error

Actual Behavior

tool_use ids were found without tool_result blocks immediately after error

Doctor Output

1. Loaded plugin is outdated
   Loaded 3.8.1, latest 3.8.3.
   Fix: Update: cd ~/.config/opencode && bun update oh-my-opencode
   Affects: plugin features

2. Comment checker unavailable
   Comment checker binary is not installed.
   Fix: Install @code-yeongyu/comment-checker
   Affects: comment-checker hook

Error Logs

Configuration

Additional Context

No response

Operating System

macOS

OpenCode Version

3.8.1

[code-yeongyu]

[sisyphus-bot]

Thank you for the detailed bug report. I have analyzed this issue thoroughly.

CONFIRMED BUG

This is a confirmed bug affecting the Prometheus → Momus workflow.

ROOT CAUSE ANALYSIS

Primary Issue: OpenCode platform bug with interleaved tool calls when subagents are invoked.

Sequence of failure:

1. Prometheus issues tool_use to call Momus via task(subagent_type="momus")
2. Momus runs and returns feedback as a separate assistant message
3. Prometheus attempts to modify the plan file (another tool call)
4. The Momus feedback message creates an "interleaved" state between tool_use and subsequent tool calls
5. Claude API validation fails with "tool_use ids were found without tool_result blocks"

OMO-side context:

• Session recovery hook exists (src/hooks/session-recovery/) and detects tool_result_missing errors
• recover-tool-result-missing.ts attempts recovery by injecting synthetic tool_result blocks
• Detection pattern: message.includes("tool_use") && message.includes("tool_result")

Why recovery fails for Momus case:
The recovery mechanism reconstructs tool results from stored metadata, but subagent boundaries complicate the tool_use ID tracking. The synthetic "Operation cancelled by user" message may not properly satisfy the APIs structural requirements when nested subagent conversations are involved.

AFFECTED FILES

File	Purpose
src/hooks/session-recovery/detect-error-type.ts	Error classification
src/hooks/session-recovery/recover-tool-result-missing.ts	Recovery logic
src/hooks/session-recovery/hook.ts	Recovery orchestration
src/agents/prometheus/high-accuracy-mode.ts	Momus invocation (line 17-35)

SEVERITY

High - Breaks a core workflow (Prometheus high-accuracy mode with Momus review).

FIX APPROACH

While this is fundamentally an OpenCode bug (as noted in the linked PR anomalyco/opencode#14456), OMO can implement mitigations:

1. Enhanced recovery for subagent contexts - Improve recover-tool-result-missing.ts to handle nested subagent tool calls
2. Momus response handling - Transform Momus feedback into proper tool_result format before API submission
3. Pre-flight validation - Add validation hook to detect tool_use/tool_result mismatches before they reach the API
4. Fallback mode - When Momus consultation triggers this error, fall back to non-Momus planning mode

WORKAROUND (for users)

Until fixed, avoid the high-accuracy Momus loop:

• When Prometheus asks "High Accuracy Review?", select "Start Work" instead
• Or disable Momus consultation in your config

---

Status: Acknowledged and queued for fix. Working on recovery logic improvements.