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 CATWILLgh/MAINFRAME --skill mainframe-go-backendgit clone --depth 1 https://github.com/CATWILLgh/MAINFRAMEWrote 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/catwillgh/mainframe/mainframe-go-backend)<a href="https://agentmods.dev/skills/catwillgh/mainframe/mainframe-go-backend"><img src="https://agentmods.dev/badge/skills/catwillgh/mainframe/mainframe-go-backend/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/catwillgh/mainframe/mainframe-go-backend"><img src="https://agentmods.dev/badge/skills/catwillgh/mainframe/mainframe-go-backend.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 | $0.00033 | $0.00893 |
| Opus 5.5 | $0.00013 | $0.00357 |
| Sonnet 5.5 | $0.00007 | $0.00179 |
| Haiku 4.5 | $0.00003 | $0.00089 |
Grade A, and why
mainframe-go-backend 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 10d 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 — 80 lines — stays where its author put it; the contents beside it link to each section on GitHub.
Go backend engineering
Apply this method whenever the active work matches the description, whether you are the primary implementer, a delegated engineer, or a reviewer. Follow the scope and authority supplied through the current execution path; this skill does not expand either.
For behavior changes, load mainframe-testing for the shared TDD and local/CI boundary, then use this skill's testing reference for stack-specific evidence.
Establish the active service boundary
Identify the Go module and package that own the behavior. Trace the real process entrypoint through registration, middleware or worker wiring, business rules, persistence and external boundaries, side effects, callers, and observable output. A package name, interface, or passing unit test alone does not prove the active runtime path.
Several modules, commands, routers, database clients, generated packages, and
test styles may legitimately coexist. Resolve ownership from go.mod,
go.work, imports, constructors, registration, process commands, build tags,
configuration, and affected tests. Read reconnaissance
when ownership or runtime wiring is unclear.
Preserve the established system
Preserve the supported Go and toolchain versions, module/workspace layout, router, persistence library, error contract, concurrency model, observability, deployment boundary, and verification conventions unless changing one is part of the assigned result. Do not introduce another router, ORM, migration tool, worker system, or abstraction layer for convenience.
Keep non-trivial business behavior independent of transport when the established
architecture supports that separation. Pass context.Context through request,
database, provider, and background boundaries; derive bounded child contexts at
the operation that owns the deadline. Treat goroutines, transactions,
connections, response bodies, timers, and channels as owned resources with a
defined completion and cleanup path.
Verify installed or selected versions before relying on version-sensitive behavior. Prefer the owning project's source and current primary documentation.
What ships with it
7 files 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.
- 10d ago Changed · +2 lines · -4 tokens per session 62acfa83cebb
- 15d ago First seen · 78 lines · 37 tokens per session scan A 9ab4fb97c7b1
mainframe-go-backend is a skill published in the GitHub repository CATWILLgh/MAINFRAME (2 stars, last pushed 4d ago), licensed MIT. It adds 33 tokens to every session and 893 once invoked, about $0.0001 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 2026-10-02.
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