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.
git clone --depth 1 https://github.com/beardfaceguy/daimonosWrote this? Show the measurements
A badge with what this costs and how it scanned, read live from this page, so it follows the numbers instead of freezing them. Markdown for a README, HTML for a documentation site or a project page.
[](https://agentmods.dev/rules/beardfaceguy/daimonos/no-thread-spawn-in-callbacks)<a href="https://agentmods.dev/rules/beardfaceguy/daimonos/no-thread-spawn-in-callbacks"><img src="https://agentmods.dev/badge/rules/beardfaceguy/daimonos/no-thread-spawn-in-callbacks/github.svg" alt="Measured on agentmods" height="20"></a>Or the 80×15 button, for a site that already has a row of RSS and ATOM ones. Only the verdict fits; the numbers stay here.
<a href="https://agentmods.dev/rules/beardfaceguy/daimonos/no-thread-spawn-in-callbacks"><img src="https://agentmods.dev/badge/rules/beardfaceguy/daimonos/no-thread-spawn-in-callbacks.svg" alt="Reviewed on agentmods" width="80" height="20"></a>What it costs to keep this loaded
Counted locally with the o200k_base tokenizer, which is exact for GPT models; Claude uses its own tokenizer and its counts differ. Treat this as one consistent yardstick across the catalogue rather than a bill. Prices are per million input tokens.
| Model | Per session | Once invoked |
|---|---|---|
| Fable 5.1 | $0.00000 | $0.00283 |
| Opus 5.5 | $0.00000 | $0.00113 |
| Sonnet 5.5 | $0.00000 | $0.00057 |
| Haiku 4.5 | $0.00000 | $0.00028 |
Grade A, and why
no-thread-spawn-in-callbacks 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 2mo ago.
A static scan of the body, not an audit. Every finding is printed with the line that produced it so you can judge whether it matters here. A mod is markdown that instructs an agent; that is exactly why what it instructs is worth reading.
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.
What it actually says
No Thread Spawning in High-Frequency Callbacks
Never use std::thread::spawn inside a callback that fires on every
filesystem event, network packet, or timer tick.
What went wrong
The pipeline cache's notify watcher callback spawned a new OS thread on
every filesystem modify/create/remove event, just to set a boolean flag.
Under heavy churn, this created hundreds of short-lived threads — an
unnecessary resource drain.
Rule
- If you only need to flip a flag, use
AtomicBoolwithOrdering::Relaxed. - If you need to send structured data, use a bounded channel
(
std::sync::mpscorcrossbeam). - If you absolutely need async from a sync callback, use
tokio::runtime::Handle::try_current()withspawn— notstd::thread::spawn+block_on.
Example
// BAD: thread per event
std::thread::spawn(move || {
rt.block_on(async { state.write().await.dirty = true; });
});
// GOOD: lock-free atomic flag
dirty_flag.store(true, Ordering::Relaxed);
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.
- 2mo ago First seen · 39 lines · 0 tokens per session scan A 81c51d578421
no-thread-spawn-in-callbacks is a cursor rule published in the GitHub repository beardfaceguy/daimonos (3 stars, last pushed today), licensed MIT. It costs nothing until one of its globs matches a file; then it loads 283 tokens. 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 2026-08-31.
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