fix(task): preserve subagent todo permissions

[armin1024]

Issue for this PR

Closes #12938

Type of change

• Bug fix

What does this PR do?

Fixes a subagent permissions bug where todowrite / todoread became unavailable
inside child sessions created through task, even when the subagent explicitly
allowed them.

Root cause:

• TaskTool passed todowrite: false and todoread: false into SessionPrompt.prompt()
• those overrides were persisted into the child session permission set
• todoread was also missing from ToolRegistry

Changes:

• stop hard-disabling todowrite / todoread in packages/opencode/src/tool/task.ts
• register TodoReadTool in packages/opencode/src/tool/registry.ts
• add regression coverage for both cases

How did you verify your code works?

• added a regression test for subagent todo permissions through task
• added a registry test to verify todoread is registered
• ran the targeted tests locally
• ran typecheck for packages/opencode

Screenshots / recordings

N/A

Checklist

• I have tested my changes locally
• I have not included unrelated changes in this PR

[github-actions]

The following comment was made by an LLM, it may be inaccurate:

I found one potentially related PR that may be addressing a similar issue:

Related PR:

• fix: propagate parent agent permissions to subagent child sessions #12584 - "fix: propagate parent agent permissions to subagent child sessions"
  • URL: fix: propagate parent agent permissions to subagent child sessions #12584
  • This PR also addresses subagent child session permissions, which is closely related to the current PR's focus on preserving todo permissions in child sessions created by TaskTool.

The current PR (18202) appears to be fixing a specific regression where todowrite/todoread permissions were being clobbered by overrides in TaskTool's SessionPrompt.prompt() call. While PR #12584 is about propagating parent permissions, it's addressing the same general area of subagent permission handling, so it's worth checking if they're addressing related root causes.

[github-actions]

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