[FEATURE]: Allow configurable subagent-to-subagent task delegation with call limits

[NamedIdentity]

Feature hasn't been suggested before.

• I have verified this feature I'm about to request hasn't been suggested before.

Describe the enhancement you want to request

Problem
Currently, task.ts hardcodes task: false for all subagent sessions (lines 65-69, 132-137), preventing any subagent from delegating to another subagent. This blocks legitimate workflows like:

• Principal-Partner delegating to Assistants
• Assistant-Sonnet having Assistant-Flash cross-check its work
• Assistant-Flash asking Assistant-Sonnet for thorough analysis

The agent config already supports granular task permissions:

assistant-sonnet: {
tools: { task: true },
permission: {
task: { *: deny, assistant-flash: allow }
}
}

But this config is ignored because task.ts unconditionally overrides it.

Proposed Solution

1. Respect agent-level task permissions instead of hardcoding task: false
2. Add optional task_limit config to prevent infinite loops:
   assistant-sonnet: {
   tools: { task: true },
   permission: {
   task: { *: deny, assistant-flash: allow }
   },
   task_limit: 3 // Max task calls per session (0 = current behavior)
   }

Use Case
Building an Agentic Collaboration Framework where:

• Principal-Opus orchestrates work
• Principal-Partner (subagent) can delegate to Assistants
• Assistant-Sonnet and Assistant-Flash can cross-check each other's work

The permission system already expresses "Sonnet can only task Flash" - it just needs to be honored.

Backward Compatibility
Default behavior unchanged - task_limit: 0 (or absent) means task tool disabled for subagents, matching current behavior. Only users who explicitly configure permissions get the new capability.

[github-actions]

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

• Subagents are using the task tool #4439: Subagents are using the task tool (reports subagents unexpectedly delegating to other agents)
• Task should inherit current agent permissions/tools for MCP #3808: Task should inherit current agent permissions/tools for MCP (discusses task tool circumventing agent permission restrictions)
• [feat] True Async/Background Sub-Agent Delegation #5887: [feat] True Async/Background Sub-Agent Delegation (related feature request for allowing subagent-to-subagent delegation with async execution)

Feel free to ignore if none of these address your specific case.

[NamedIdentity]

I am exploring trying to make a PR for this myself. I have no coding background, or developer experience. But I figure it's time to try to vibe code a contribution.

It also seemed logical, that at the very least I need to construct a more detailed design for the PR to make sure it does what my use-case requires.

My thinking is, even if I fail miserably in producing fully working code that can be pulled into the repo, I will succeed in defining a design that experienced developers managing the project can use to make a proper PR.

[akirfman]

+1 to this feature request.

I'd even be inclined to view parts of this as a bug since I was actively able to leverage subagents that could invoke other subagents before the v1.1.1 release.

Example from v1.0.223 (https://github.com/anomalyco/opencode/blob/01237c5325f5c3eda142f459b22f902b5aa07d7c/packages/opencode/src/tool/task.ts)

      const result = await SessionPrompt.prompt({
        messageID,
        sessionID: session.id,
        model: {
          modelID: model.modelID,
          providerID: model.providerID,
        },
        agent: agent.name,
        tools: {
          todowrite: false,
          todoread: false,
          task: false,
          ...Object.fromEntries((config.experimental?.primary_tools ?? []).map((t) => [t, false])),
          ...agent.tools,
        },

Even though task was hardcoded to false, I could override it by adding task: true into my subagent definitions. For example, I have a research orchestrator subagent that delegates to more focused subagents scoped to different groups of docs and sources that I didn't want to group together into one agent.

Agent YAML frontmatter example:

---
description: Research coordinator that routes queries to appropriate sources and consolidates results. Cross-cutting utility for all SDLC agents.
mode: subagent
tools:
  // ... other tools here
  task: true
---

Working Example from v1.0.223:

Running the same test with the same config on newer versions of OpenCode doesn't work any longer. I'm sure there's more nuance to the topic here in general, but it would be nice to have that optional override behavior back.

[NamedIdentity]

I have submitted a PR which provides these features. #7756