[FEATURE] add agent_type field to PreToolUse hook

Preflight Checklist

• [x] I have searched existing requests and this feature hasn't been requested yet
• [x] This is a single feature request (not multiple features)

Problem Statement

I need to gate ToolUse differently depending on the subagent that is running (eg a python-coder subagent shouldn't be able to write to a test*.py file, but python-test subagent can write to it).

Proposed Solution

If the PreToolUse hook had the same agent_type field as SubagentStart then this would be easy to implement.

Alternative Solutions

right now i do a messy pattern of capturing which subagent is running via SubagentStart, and then reading this in my PreToolUse hook

  "hooks": {
    "SubagentStart": [
      {
        "matcher": "*",
        "hooks": [
          {
            "type": "command",
            "command": "sh -c 'cat; printf \"\\n\"' >> .claude/subagents.jsonl"
          }
        ]
      }
    ]
}

this is fragile.

Priority

Medium - Would be very helpful

Feature Category

Developer tools/SDK

Use Case Example

_No response_

Additional Context

_No response_