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 allemaar/open-skills --skill freshness-contractgit clone --depth 1 https://github.com/allemaar/open-skillsWrote 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/allemaar/open-skills/freshness-contract)<a href="https://agentmods.dev/skills/allemaar/open-skills/freshness-contract"><img src="https://agentmods.dev/badge/skills/allemaar/open-skills/freshness-contract/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/allemaar/open-skills/freshness-contract"><img src="https://agentmods.dev/badge/skills/allemaar/open-skills/freshness-contract.svg" alt="Reviewed on agentmods" width="80" height="20"></a>- NVIDIA SkillSpector pass
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 | $0.00203 | $0.01529 |
| Opus 5 | $0.00102 | $0.00764 |
| Sonnet 5 | $0.00041 | $0.00306 |
| Haiku 4.5 | $0.00020 | $0.00153 |
Grade A, and why
freshness-contract 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 11d 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.
How it starts
The opening of the file, as written. The whole thing — 79 lines — stays where its author put it; the contents beside it link to each section on GitHub.
/freshness-contract
EXPERIMENTAL. A lookup, not a judgment ritual: it should cost LESS than the vibes it replaces. Fires only when prior evidence is about to be reused for a decision — never on every read, never as per-phase bookkeeping. It decides whether old proof still counts; what fresh proof must show belongs to your verification tools.
The design is deliberately isomorphic to HTTP caching (RFC 9111): explicit invalidation beats heuristics, conflicting signals resolve restrictively, and nothing is served stale silently. No TTL numbers ship in v1 — every "how old is too old" constant would be invented; the table routes by class and events, which are observable.
Step 1 — classify the artifact (volatility class)
| Class | Meaning | Examples |
|---|---|---|
| stable | exact version-pinned evidence, used for a question about that exact version — byte stability is not applicability: a superseded spec's old bytes still match while the governing version moved | a released spec consulted AS that release, a frozen/hash-pinned artifact, an archived record. Supersession or a dependency-version change is a named invalidator whenever the decision asks what is CURRENT |
| write-coupled | valid until someone writes to the source | a file you read this session, an index entry, a config, a map/roster document |
| env-coupled | valid until the environment shifts | a passing test that touches network/services/installed tools, a capability probe, a build result |
| clock-coupled | decays with time regardless of writes | anything embedding "current" state: prices, live statuses, date-dependent results |
| report | someone's account of state, not state itself | worker/subagent reports, peer summaries, self-reports of any kind |
Class is assigned per artifact kind at first encounter, not re-judged per use by whoever wants to skip a re-read.
Step 2 — check the observable signals
- Intervening writes — has the source (or its declared dependencies) changed since
as_of? (fingerprint, mtime, generation stamp, commit) - Named invalidators — did a declared invalidating event occur? (roster change, deploy, sync, schema bump, "re-prime after write")
- Decision leverage — is the reuse load-bearing for a decision, release, or Handler-facing claim, or merely orientation? Leverage is non-downgradable when the result supports a release, an irreversible or external action, a formal gate, or a Handler-facing recommendation — those are high, not judgment calls.
- Discriminator availability — does a cheap signal exist that is exclusive to the fresh state (a hash to recompute, a header to stat, a count to re-derive)?
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.
- 11d ago First seen · 79 lines · 203 tokens per session scan A 3e447623c203
freshness-contract is a skill published in the GitHub repository allemaar/open-skills (14 stars, last pushed today), licensed Apache-2.0. It adds 203 tokens to every session and 1,529 once invoked, about $0.0010 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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