research(core): native read-only subagents for parallel information gathering

[bug-ops]

Description

Cline v3.58 introduced native subagents — the main agent can spawn focused read-only sub-tasks that run in parallel, each with their own context window. Each subagent can read files, search code, list directories, and run read-only commands, but cannot write files, apply patches, or spawn further subagents.

This pattern is relevant to Zeph's orchestration layer: currently, multi-step information gathering is sequential within the agent loop. Parallel read-only subagents could significantly reduce latency for tasks like "review these 5 files and summarize changes" or "search for X across the codebase."

Reference

• Cline v3.58 subagents: https://docs.cline.bot/features/subagents
• Claude Code also uses Task subagents for parallel exploration

Zeph Status

No equivalent. Zeph's orchestrator supports DAG-based multi-step execution but not lightweight read-only parallel sub-tasks within a single session.

Potential Implementation

• Spawn tokio tasks with read-only access to the codebase
• Each subagent gets a fresh context window with a focused prompt
• Results aggregated by the main agent loop
• No tool execution or file modification allowed in subagents

Priority

P4 — exploratory. Useful for complex codebase analysis tasks but not blocking core functionality.