6.4 KiB
| name | description |
|---|---|
| claude-subagents | Spin up a short-lived headless `claude` sub-instance to grind through a well-scoped, mechanical batch (bulk relabeling, a repetitive find/replace, a mechanical migration) instead of burning your own context on it inline. Use this when a task has a clear, describable recipe and is either big enough to eat your context or long enough that you'd rather not babysit it. Not for judgement-heavy work, anything needing operator back-and-forth, or a task whose blast radius you can't bound up front. |
Ephemeral Sub-Agents
A sub-instance you spawn inherits the same filesystem and credentials you have. This is a first-class tool for offloading a bounded, mechanical batch.
When to use it
- Yes: mechanical batches with a clear recipe (relabel N issues, rewrite a call-site pattern, migrate a config field), especially when the batch would eat your context or take long enough that you'd rather not babysit it turn-by-turn.
- No: judgement-heavy work, anything needing back-and-forth with a human, or a task whose blast radius you can't bound up front.
The subagent MCP tools
Your container's subagent MCP server (hive-subagent-daemon) runs this
skill's recipe for you:
start(name, prompt_file, model?, trigger?)
continue(name, prompt, model?)
status(name)
interrupt(name, force?)
start and continue return as soon as the process is confirmed
running, not once it finishes — a completion lands as a todo
(get_loose_ends), same as any other producer. Use status for a
zero-cost "is it still going" check; reach for continue only once you
actually have a new instruction for it, since that spends a turn.
interrupt genuinely stops a running turn (force: true for SIGKILL).
Model choice, prompt hygiene, splitting big batches, verify-then-report — everything else in this skill — applies exactly the same whether you're calling the tool or thinking through the recipe by hand.
Prompt hygiene - this is where batches succeed or fail
- Concrete constants, not "figure it out": exact ids, field names, option values, endpoints.
- Critical ordering rules, spelled out - the sub-agent won't infer invariants you don't state.
- Explicit scope + exemptions, plus a fallback rule for ambiguous cases: "leave it as-is where genuinely unclear; do not guess."
- Ask for a report file - per-item results + anything skipped and why, so you can verify without re-deriving.
- Tune on ONE item first, eyeball the result, fix the prompt, then turn it loose on the full batch. A prompt bug replicated across 100 items is 100 cleanups.
Split a big independent batch across parallel subagents
One subagent is a sequential worker — a 50-item batch takes roughly 50 items' worth of wall-clock even though nothing about the recipe forces serialization. If the items are independent (each one touches its own file/issue/row, nothing depends on another item's result) and the batch is big enough that wall-clock matters, chunk it across N subagents running at once instead of handing the whole thing to one.
- Split by natural boundaries, not an arbitrary item count — one subagent per file, per directory, per module, per label, whatever grouping keeps each worker's slice self-contained. A worker that has to coordinate with another worker mid-task isn't actually independent work; re-scope the split until it is.
- Isolate each worker's writes. For a git-based batch, give each
worker its own
git worktree(own working directory, own branch, same underlying repo — cheap, no full reclone) so N workers editing different files never race on the same working tree or index. For a non-git batch (issue relabeling, API calls), independent items don't need filesystem isolation at all — just launch N in parallel. - Launch all N and don't babysit any single one — same as the
one-subagent case, just N
startcalls instead of one. Check on them as a batch, not by polling each individually in a loop. - Mind the container's memory cap before picking N. Your whole
container shares one
MemoryMax(a few GB by default) with every subagent you spawn and your own process. Aclaudeprocess plus its MCP servers can hold several hundred MB to ~1GB depending on the task; spawning a dozen at once on a small container doesn't just slow things down, it can OOM the whole container — taking your own in-flight turn down with it, not just the subagents. Rule of thumb: 2-4 concurrent workers on a default-sized container; checkfree -h(or ask whoever owns the container's config for itsMemoryMax) before going higher, and chunk a bigger batch into successive waves of that size rather than firing everything at once. - You own the merge. Once all N report done, review + verify each worker's slice (same "don't trust the self-report blind" rule as below), then combine — for a git-based split, that's you merging N branches (or cherry-picking) into one, not each worker pushing/PRing its own slice.
Skip this for a batch small enough to finish in a couple minutes single- threaded — the coordination overhead isn't worth it below that size.
Resume for follow-ups
continue reuses the same session, so the sub-agent keeps every constant
and gotcha it already discovered instead of re-learning the surface from
a cold prompt. Reach for start under a new name only for a genuinely
unrelated task.
Verify, then report
On completion: read the report file, spot-check a handful of results yourself (don't trust the self-report blind), then summarize. Surface anything the sub-agent left ambiguous or exempted for a human call.
Pitfalls (all observed in practice)
- Using a model bigger than yourself → paying premium cost for mechanical work that didn't need it.
- Skipping the one-item tuning pass → a systematic mistake smeared across the whole batch.
start-ing fresh instead ofcontinue-ing for a follow-up → throws away all the context the first pass earned.- Baking an unverified assumption into the recipe - if a quick check suggests something "isn't possible" or "doesn't exist," confirm it before writing that conclusion into the prompt; a wrong assumption gets replicated across the whole batch.
- Handing a big independent batch to one subagent instead of splitting it across several in parallel - a 50-item sequential run burns wall- clock the split-by-worktree approach above would've avoided for free.