feat: add share_sandbox option to delegate_task

[malaiwah]

Summary

• Adds share_sandbox boolean parameter to delegate_task that lets subagents reuse the parent's sandbox container instead of getting an isolated one
• When share_sandbox=True, the child's run_conversation receives the parent's effective_task_id, so the Docker backend creates no new container — the child operates in the same filesystem
• Also fixes a pre-existing bug where the direct delegate_task call sites in run_agent.py were missing acp_command and acp_args parameters

Use case

Explorer/research subagents that need access to the parent's already-prepared workspace (source code cloned, packages installed, files created) without the overhead and delay of spinning up a new sandbox container.

Changes

• tools/delegate_tool.py: Added share_sandbox to function signature, schema (top-level + per-task), and registry handler. Child system prompt notes shared sandbox when enabled.
• run_agent.py: Store _effective_task_id on the agent instance. Added missing acp_command/acp_args to both direct delegate_task call sites.
• tests/tools/test_delegate.py: 4 new unit tests in TestShareSandbox class. Fixed existing test that broke from the task_id kwarg change.

Test plan

• 71 unit tests pass (tests/tools/test_delegate.py)
• New tests verify: parent task_id passed when shared, None when not shared, prompt note appended, schema includes share_sandbox
• End-to-end: parent creates file → delegates with share_sandbox=true → subagent reads same file

🤖 Generated with Claude Code

[alt-glitch]

Related to #16177 (merged, auto-shares terminal sandbox). This adds explicit user-facing opt-in via share_sandbox parameter.

[teknium1]

Thanks for the contribution. This is an automated hermes-sweeper review; the requested behavior is already implemented on current main.

• Member discussion already identified merged feat(terminal): collapse subagent task_ids to shared container #16177. Its implementation commit is f65177639acaee952015617c7fffef4f1b35ba90.
• tools/terminal_tool.py:1123-1155 maps normal subagent task IDs to the shared "default" container, so delegated children already share the parent's workspace, packages, and filesystem.
• tools/file_tools.py:1030-1031 and tools/code_execution_tool.py:641 use the same resolver, covering file and code-execution paths as well as terminal execution.
• tools/delegate_tool.py:1874-1924 intentionally keeps a distinct child task ID for file-state coordination and TUI/subagent tracking; using the parent task ID directly would lose that separation without adding sandbox sharing.
• tests/tools/test_shared_container_task_id.py:45-103 covers shared subagent lookup and the retained per-task isolation override for RL/benchmark environments.