Subagents Bypass Plan Mode READ-ONLY Restrictions #26514

Description

Bug Report: Plan Mode Permission Bypass via Subagents

Description

In Plan Mode (READ-ONLY phase), the main agent's file editing permissions are correctly restricted, but subagents retain full file modification capabilities, creating a security bypass.

Steps to Reproduce

1. Enable Plan Mode in opencode
2. As the main agent, attempt to use edit or write tool → Blocked by rules
3. Use the task tool to spawn a subagent (type: general)
4. Instruct the subagent to use edit or write tool → Succeeds

Expected Behavior

Subagents should inherit the same READ-ONLY restrictions as the main agent when Plan Mode is active.

Actual Behavior

• Main agent: edit/write blocked with error: "The user has specified a rule which prevents you from using this specific tool call"
• Subagent: edit/write execute successfully, bypassing Plan Mode restrictions

Impact

This is a permission bypass vulnerability. Users enable Plan Mode to prevent unintended modifications during planning/review phase. The subagent loophole allows circumventing this safety mechanism.

Tools Affected

• edit (file editing)
• write (file creation)
• Likely affects other modification tools as well

Environment

• OS: Windows (win32)
• Shell: PowerShell 7+

Plugins

No response

OpenCode version

No response

Steps to reproduce

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Screenshot and/or share link

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Operating System

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Terminal

No response