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 blackmo18/realm --skill realm-fathomgit clone --depth 1 https://github.com/blackmo18/realmWrote 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/blackmo18/realm/realm-fathom)<a href="https://agentmods.dev/skills/blackmo18/realm/realm-fathom"><img src="https://agentmods.dev/badge/skills/blackmo18/realm/realm-fathom/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/blackmo18/realm/realm-fathom"><img src="https://agentmods.dev/badge/skills/blackmo18/realm/realm-fathom.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 | $0.00074 | $0.01209 |
| Opus 5.5 | $0.00030 | $0.00484 |
| Sonnet 5.5 | $0.00015 | $0.00242 |
| Haiku 4.5 | $0.00007 | $0.00121 |
Grade A, and why
realm-fathom 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 1mo 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 — 125 lines — stays where its author put it; the contents beside it link to each section on GitHub.
realm-fathom
Investigate anything. Code truth + vault context. Drift flagged.
Host invocation: Claude Code and Gemini use /realm-fathom; Codex uses $realm-fathom.
Syntax
/realm-fathom function:validateUser # named function
/realm-fathom class:UserService # named class
/realm-fathom system:PaymentPipeline # named subsystem
/realm-fathom "how does auth flow work" # freeform question
/realm-fathom validateUser # bare name (auto-detect type)
/realm-fathom "payment pipeline" # concept
Examples
/realm-fathom function:validateUser
→ Live: signature, flow, callers, error paths
→ Vault: why JWT, ADR refs, invariant notes
→ DRIFT flagged if vault says bool return but code returns Result<User>
/realm-fathom "how does the auth middleware chain work"
→ Investigator maps relevant files + functions end-to-end
→ Vault adds architectural intent, prior decisions
→ VERDICT: consolidated what + why
/realm-fathom class:PaymentService
→ Full class: responsibility, methods, deps from live code
→ Vault: why this abstraction exists, linked ADRs
Source Hierarchy
| Source | Authoritative for |
|---|---|
Live code — graphify first, cavecrew-investigator as backup |
behavior, signatures, flow, callers, current state |
| Vault (indexed inline lookup) | why, ADR refs, architectural intent, invariant rationale |
| Conflict | flagged as VAULT DRIFT — never silently blended |
Code truth is resolved cheapest-first: graphify's cached graph answers most
queries for the cost of one graphify query call, no subagent spawn. The
cavecrew-investigator crawler only runs as backup — when graphify is
missing, stale (source files changed since last index), or its match is too
thin to answer the query. This keeps token cost flat without losing
context: the report always states which source answered (graphify vs
investigator) so nothing is silently degraded.
Guards
What ships with it
5 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.
- 1mo ago First seen · 125 lines · 74 tokens per session scan A 43c2bd8e91a4
realm-fathom is a skill published in the GitHub repository blackmo18/realm (0 stars, last pushed 2mo ago), licensed MIT. It adds 74 tokens to every session and 1,209 once invoked, about $0.0003 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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