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 rules/eagonmeng/sync-blank/concept-implementationgit clone --depth 1 https://github.com/eagonmeng/sync-blankWhat 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 | $0.00303 | $0.00303 |
| Opus 5 | $0.00151 | $0.00151 |
| Sonnet 5 | $0.00061 | $0.00061 |
| Haiku 4.5 | $0.00030 | $0.00030 |
Grade A, and why
concept-implementation 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.
What it actually says
Implementing Concepts
- Use TypeScript
- Each concept is a single class with the name
${name}Concept, and should be contained in a single .ts file under the directory./concepts - All actions must take exactly one argument, and return one argument
- The shape of the input and output arguments are described in the corresponding
concept specification in the form of
key: type - The names of actions must match up exactly with those in the specification
- For the purposes of the
whereclause in the synchronizations, and for generally querying state, each concept may also have query functions - Query functions MUST start with the underscore character
_to distinguish them from actions - Query functions MUST NOT update state or perform side-effects
- Query functions will also take as input a single argument with named keys, but
instead return an array of such arguments corresponding to the names of
the desired state. This is because query functions enable synchronizations in
the
whereclause to e.g. declaratively find all comments related to a post, where each comment becomes a new frame for the purposes of thethenclause, such as deleting all comments of a post when the post is deleted. - In general, if a concept is well behaving, you should not need to update it except to add query functions for the purposes of accessing state
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 · 27 lines · 303 tokens per session scan A f75b170cd468
concept-implementation is a cursor rule published in the GitHub repository eagonmeng/sync-blank (4 stars, last pushed 1mo ago), licensed Apache-2.0. It adds 303 tokens to every session, about $0.0015 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 2026-08-31.
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