Borrowing it
Nothing to install: this file belongs to extra-org/extra. Take a copy, put it at the same path in your own repository, and replace the rules that are about this project with yours.
curl -O https://raw.githubusercontent.com/extra-org/extra/main/.claude/skills/runtime-engine/SKILL.mdgit clone --depth 1 https://github.com/extra-org/extraWrote 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/extra-org/extra/runtime-engine)<a href="https://agentmods.dev/skills/extra-org/extra/runtime-engine"><img src="https://agentmods.dev/badge/skills/extra-org/extra/runtime-engine/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/extra-org/extra/runtime-engine"><img src="https://agentmods.dev/badge/skills/extra-org/extra/runtime-engine.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 | $0.00041 | $0.00501 |
| Opus 5.5 | $0.00016 | $0.00200 |
| Sonnet 5.5 | $0.00008 | $0.00100 |
| Haiku 4.5 | $0.00004 | $0.00050 |
Grade A, and why
runtime-engine 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 2mo 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
Skill: Runtime Engine
When to use this skill
Use this when modifying RuntimeEngine, ExecutionContext, agent execution, or
the request lifecycle. Primary tasks: tasks/0003-compiled-agent-graph.md,
tasks/0004-runtime-engine.md.
Files to read first
AGENTS.mddocs/ARCHITECTURE.mddocs/RUNTIME_LIFECYCLE.mddocs/adr/0001-runtime-engine-created-once.md
Architecture rules
RuntimeEngineis long-lived, created once at startup from theCompiledAgentGraph.ExecutionContextis per-request and carries all request-scoped state.- The compiled graph is immutable at runtime.
- The runtime operates only on compiled, typed models — never raw YAML.
Implementation rules
- Construct the engine only on startup paths; never inside request handlers.
- Do not put request state (identity, tenant, current request, rendered prompts)
on
RuntimeEngineor the compiled graph. - Pass
ExecutionContextexplicitly through routing, context resolution, prompt rendering, and tool execution. - Keep the engine concurrency-safe by keeping it stateless w.r.t. requests.
- Build the engine in
src/agentplatform/runtime; the graph insrc/agentplatform/graph.
Validation checklist
- Engine constructed once (startup), not per request.
- No request-scoped fields on the engine or graph.
- All per-request data lives on
ExecutionContext. - Compiled graph treated as immutable.
- Tests cover concurrent requests not leaking state.
-
make checkpasses.
Common mistakes to avoid
- Recreating the runtime or recompiling the graph per request.
- Storing "current user/request" on the engine.
- Mutating the compiled graph during execution.
- Hidden global/singleton request 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.
- 2mo ago First seen · 63 lines · 41 tokens per session scan A 6c5d9781ca7b
runtime-engine is a skill published in the GitHub repository extra-org/extra (117 stars, last pushed 5d ago), licensed MIT. It adds 41 tokens to every session and 501 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 2026-08-30.
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