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 t1djani/servo --skill seal-plangit clone --depth 1 https://github.com/t1djani/servoWrote 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/t1djani/servo/seal-plan)<a href="https://agentmods.dev/skills/t1djani/servo/seal-plan"><img src="https://agentmods.dev/badge/skills/t1djani/servo/seal-plan/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/t1djani/servo/seal-plan"><img src="https://agentmods.dev/badge/skills/t1djani/servo/seal-plan.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 | $0.00051 | $0.00697 |
| Opus 5 | $0.00026 | $0.00349 |
| Sonnet 5 | $0.00010 | $0.00139 |
| Haiku 4.5 | $0.00005 | $0.00070 |
Grade A, and why
seal-plan 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 9d 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 — 32 lines — stays where its author put it; the contents beside it link to each section on GitHub.
seal-plan
A plan is the hardest artifact in the flow. Its whole job is to be portable and deterministic: hand it to another conversation, or a smaller model, and you should get the same result. That only holds if the plan is sealed. Three properties seal it.
The three properties
-
Closed — zero open decisions. Every choice was made upstream (
expert-panel,shape-spec). The plan is pure convergence. A plan that still contains a decision delegates that divergence to execution time, where each executor will resolve it differently — non-deterministic by construction. If you find an open choice while writing the plan, stop and settle it upstream. -
Pinned to a machine-checkable acceptance oracle. "Same result" needs a definition of "same". It is behavioral equivalence: the same acceptance criteria pass, the same invariants hold — not character-identical output. So the plan must name an acceptance oracle that a machine can check (tests, criteria), and snapshot the volatile part into the plan itself. A plan whose acceptance target can drift between writing and execution is not deterministic. (This is where a plan differs from a spec: the spec points at a live oracle for freshness; the plan snapshots for determinism.)
-
Written for the weakest executor (plan-to-the-floor). Portability is relative to a capability floor. Write the plan for the least capable model you intend to run it on: exact file paths, complete code in every step, exact commands with expected output, zero placeholders. Writing for a strong model and running on a weak one breaks; the reverse is safe. If you will delegate to a cheaper model, the plan must be constrained enough that the cheap model cannot go wrong.
Procedure
- Map the files each task touches, then break the work into bite-sized, test-first tasks. Embed the spec's invariants inline so the executor cannot miss them.
- For each task: the failing test, the command to see it fail, the minimal code, the command to see it pass, the commit. Real content in every step.
- Snapshot the acceptance criteria into the plan.
- Gate the plan. Run
servo-gateagainstspec(does the plan cover it, no creep?) and against the plan's own closedness (any open decision, placeholder, or unreachable acceptance check is aSTOP). Fix before executing.
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.
- 9d ago First seen · 32 lines · 51 tokens per session scan A 8ffb517177f1
seal-plan is a skill published in the GitHub repository t1djani/servo (1 stars, last pushed 2mo ago), licensed MIT. It adds 51 tokens to every session and 697 once invoked, about $0.0003 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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