What is SubagentStart?

A startup hook that runs a command when a coding subagent begins. The command adds instructions for using a tree-sitter code index, a tool that understands source-code structure, in supported languages.

Use it to guide subagents toward the repository's code index for one-off searches, implementation lookups, caller searches, or batched commands.

It gives newly started subagents a shared way to search code, find callers, and inspect implementation details without relying only on plain text search.

SubagentStart — Hook by JaredStewart

Install

Getting it into your agent

One page per mod, every tool's command on it. A separate URL per tool would split the same page into five that compete with each other.

agentmods

npx agentmods add hooks/jaredstewart/coderlm/subagent-start

Clone the repo

git clone --depth 1 https://github.com/JaredStewart/coderlm

Per session not measured What this adds to a session before it is invoked.

When invoked not measured Not applicable: nothing here is loaded into a session.

Security scan A 0 findings. Scan, not verified.

Origin original No closer match found in the catalogue.

Security

Grade A, and why

SubagentStart scanned grade A with 0 findings against 26 rules in 11 categories — prompt injection, anti-refusal, data exfiltration, privilege escalation, supply chain, agent snooping, system-prompt leakage, SSRF and excessive agency — measured yesterday.

A static scan of the commands this hook runs, not an audit. A hook is shell that executes on your machine at the event it names, which is why every command in it is printed with what was found.

Nothing flagged

None of the 26 patterns this scan looks for appear in this file: no shell pipes, no recursive deletes, no credential paths, no hidden text, no instruction-override or anti-refusal phrasing, no agent-config snooping. That is not a guarantee, it is the absence of the things that are checkable.

plugin/hooks/hooks.json · 12 lines

What it actually says

{
  "SubagentStart": [
    {
      "hooks": [
        {
          "type": "command",
          "command": "echo '{\"hookSpecificOutput\":{\"hookEventName\":\"SubagentStart\",\"additionalContext\":\"For code in supported languages (Rust, Python, TypeScript, JavaScript, Go, Java, Scala, Ruby, PHP, Zig), use the coderlm tree-sitter index. CLI=\\\".claude/coderlm_state/coderlm_cli.py\\\". For one-off: python3 $CLI search/impl/callers. For batching: python3 $CLI batch --commands \\\"...\\\" or python3 $CLI exec --code \\\"...\\\". Always include actual code extracts in answers, not just prose.\"}}'"
        }
      ]
    }
  ]
}

Changes

What this file has done since we first saw it

Hashed on every crawl. A supply-chain change to an agent config is a question of when, not whether, so the history is kept rather than the latest state alone.

yesterday First seen · 12 lines scan A d4e06926d3ee

Subscribe to this mod's changes

SubagentStart is a hook published in the GitHub repository JaredStewart/coderlm (300 stars, last pushed 3mo ago), licensed MIT. Its token cost is not measured: a hook is shell that never enters the context. A static security scan graded it A with 0 findings. No closer match exists in the catalogue, so it is treated as the original; first seen 2026-08-30.

Building agents Research

SubagentStart

Getting it into your agent

Grade A, and why

Nothing flagged

What it actually says

What this file has done since we first saw it

Other hooks, from other repositories

SubagentStop

SubagentStop

SubagentStop

Stop

SubagentStart

SubagentStop