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 skills add hani-q/qstack --skill qstack-separate-before-serializing-shared-stategit clone --depth 1 https://github.com/hani-q/qstackWrote 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/skills/hani-q/qstack/qstack-separate-before-serializing-shared-state)<a href="https://agentmods.dev/skills/hani-q/qstack/qstack-separate-before-serializing-shared-state"><img src="https://agentmods.dev/badge/skills/hani-q/qstack/qstack-separate-before-serializing-shared-state/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/skills/hani-q/qstack/qstack-separate-before-serializing-shared-state"><img src="https://agentmods.dev/badge/skills/hani-q/qstack/qstack-separate-before-serializing-shared-state.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 | $0.00054 | $0.00484 |
| Opus 5.5 | $0.00022 | $0.00194 |
| Sonnet 5.5 | $0.00011 | $0.00097 |
| Haiku 4.5 | $0.00005 | $0.00048 |
Grade A, and why
qstack-separate-before-serializing-shared-state 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 1mo 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
Separate before serializing shared state
Instructions and conventions are not concurrency control. Start by removing the shared write target. Add serialization only when one canonical writer is a real domain invariant.
Decide from ownership
- Inventory every mutable object and every actor that can write it. Include files, branches, database rows, keys, caches, queues, and in-memory state.
- Ask whether the actors publish independent facts. If they do, give each actor its own file, key, branch, or state directory and merge only at a read-only reporting boundary.
- Confirm that the split removes shared mutation. Two workers writing separate fields of one JSON document still share a write target; separate documents with one owner each do not.
- If one shared object is required, choose structural serialization: a single-writer actor, sequential phases, a lockfile with defined stale-lock behavior, an atomic transaction, or compare-and-swap.
- Prove the design under overlap, retry, crash, and stale-state scenarios.
Report the ownership map, the sharing that can be removed, any invariant that requires serialization, and the concrete mechanism enforcing it. A request for analysis does not authorize changing the system. Assess compatibility and migration before changing a persisted format, public interface, or branch workflow. It also does not authorize commits, pushes, publishing, deployment, or external messages.
Adapted from Lauren Tan's PStack
principle-separate-before-serializing-shared-state
at commit 60c641e4fad674784b30abcf9f8915dea39df38d under the MIT License.
See third-party notices.
What ships with it
1 file beside SKILL.md in the same directory: the scripts, references and assets a skill reads on demand. Not counted in the per-session cost; read them before you install if any of them is executable.
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.
- 1mo ago First seen · 42 lines · 54 tokens per session scan A 86ed5da0470b
qstack-separate-before-serializing-shared-state is a skill published in the GitHub repository hani-q/qstack (7 stars, last pushed 3d ago), licensed MIT. It adds 54 tokens to every session and 484 once invoked, about $0.0002 per session on Opus 5.5. 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 2026-08-31.
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