Most Claude Code guides stop at CLAUDE.md and slash commands. The real power is in hooks, subagents, and piping - and I haven’t seen many people write about actually using them.
Hooks - Let Claude Run Your Tests
Hooks fire shell commands in response to Claude Code events. Before a tool, after a tool, when a session ends. You configure them in ~/.claude/settings.json.
The one I use constantly - auto-run tests after any file edit:
{
"hooks": {
"PostToolUse": [{
"matcher": "Edit|Write",
"hooks": [{
"type": "command",
"command": "cd $CWD && bun test --bail 2>&1 | tail -10"
}]
}]
}
}Claude edits a file, hook fires, tests run, output gets injected back as context. Claude sees if it broke something and can fix it without you asking. That’s the part that felt like a mode switch for me - it stops being reactive and starts being anticipatory.
The other one I use is PreToolUse to inject reminders before Claude touches the shell:
{
"hooks": {
"PreToolUse": [{
"matcher": "Bash",
"hooks": [{
"type": "command",
"command": "echo 'Reminder: does this command modify production state?'"
}]
}]
}
}The hook output lands in a <system-reminder> that Claude reads before proceeding. Soft guardrail, not a hard block - but it catches things.
Subagents - Two Things at Once
Subagents let Claude Code delegate work to a separate agent instance while the main conversation keeps going. Independent work in parallel, basically.
Where I actually use this: research while planning. “Spin up an agent to read the Astro content collection docs and summarize the relevant API” - while I’m iterating on architecture in the main conversation. The subagent goes off, does the reading, reports back. No context switching from me.
If you’re using oh-my-claudecode (which I covered in the workflow post), /team and /ultrawork handle subagent spawning automatically. But you can also just ask Claude directly: “Run a background agent to explore this directory and summarize what it finds.”
The rule is independent tasks only. Subagents that share state get messy fast. But for parallel exploration or running a test suite while the main agent keeps writing? The speedup is real.
Piping - Treating Claude Like an Actual Shell Tool
The -p flag runs Claude Code headless - one prompt, stdout, exit. That’s all you need to start chaining it with other things.
# Pipe a diff, get a Slack message
git diff HEAD~1 | claude -p "Write a casual Slack update summarizing these changes for my team"
# Chain Claude with Claude
claude -p "What are the main architectural decisions in this repo?" \
| claude -p "Turn this into a 3-bullet onboarding summary"The git diff → Slack message one I use every few days. Two commands, no copy-paste, no manual writing. It’s a small thing, but it’s the difference between Claude Code living in a chat window versus fitting into your actual shell workflow.
The MCP integrations post covers the external connections - this is the plumbing that makes those integrations actually do something.
