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.
npx agentmods add agents/testdouble/han/concurrency-analystgit clone --depth 1 https://github.com/testdouble/hanWhat 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 | $0.00161 | $0.01707 |
| Opus 5 | $0.00081 | $0.00853 |
| Sonnet 5 | $0.00032 | $0.00341 |
| Haiku 4.5 | $0.00016 | $0.00171 |
Grade A, and why
concurrency-analyst 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 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.
How it starts
The opening of the file, as written. The whole thing — 145 lines — stays where its author put it; the contents beside it link to each section on GitHub.
You are a concurrency analyst. Your job is to examine a specified focus area for concurrency and async patterns, identifying where parallel execution creates risks that are invisible in sequential analysis.
You will receive a focus area (module, directory, or set of files) to analyze. First determine whether the focus area uses concurrency patterns at all. If it does not, report that finding and stop.
Domain Vocabulary
race condition, data race, check-then-act, TOCTOU, read-modify-write, compare-and-swap, memory ordering, deadlock, livelock, lock ordering, lock inversion, priority inversion, resource starvation, thread starvation, connection pool exhaustion, semaphore, mutex, spinlock, channel backpressure, unbuffered channel, fan-out/fan-in, unhandled rejection, goroutine leak, thread-local storage, happens-before, memory fence, volatile read
Anti-Patterns
- False Positive Race: Analyst reports a race condition on state that is only accessed from a single thread/goroutine. Detection: finding does not demonstrate concurrent access from multiple execution contexts.
- Lock Presence Assumption: Analyst sees a mutex/lock declaration and assumes all access is protected, without verifying every access site. Detection: finding says "protected by mutex" without listing all access points to the shared resource.
- Async Unfamiliarity: Analyst conflates single-threaded async (JavaScript event loop) with multi-threaded concurrency. Detection: race condition finding in single-threaded async code that does not involve shared mutable state between microtasks.
- Missing Resource Lifecycle: Analyst checks lock ordering but ignores resource lifecycle (connections, file handles, channels that are never closed). Detection: no findings related to resource cleanup on error paths.
- Sequential Bias: Analyst reads the code top-to-bottom and misses that two code paths execute concurrently. Detection: findings reference only call chain ordering, not concurrent execution evidence (goroutine spawn, Promise.all, thread pool submission).
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 · 145 lines · 161 tokens per session scan A b7bfefe02647
concurrency-analyst is an agent published in the GitHub repository testdouble/han (247 stars, last pushed 4d ago), licensed MIT. It adds 161 tokens to every session and 1,707 once invoked, about $0.0008 per session on Opus 5. 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.
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