Agentlas OS is a local-first system for creating, storing, borrowing, and running specialist AI agents and temporary agent teams through supported hosts and models. It serves people who want reusable agents that remain available across computers and model workspaces, and the catalogue contains its skills, commands, hooks, agents, instructions, plugin, and rule.
Getting it into your agent
There is no command for this one: it runs only inside a plugin, and the catalogue could not identify which plugin ships it. The source is linked below.
Wrote 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/agentlas-ai/agentlas-os/hephaestus-build)<a href="https://agentmods.dev/skills/agentlas-ai/agentlas-os/hephaestus-build"><img src="https://agentmods.dev/badge/skills/agentlas-ai/agentlas-os/hephaestus-build.svg" alt="Measured on agentmods" 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 | $0.00060 | $0.02083 |
| Opus 5 | $0.00030 | $0.01042 |
| Sonnet 5 | $0.00012 | $0.00417 |
| Haiku 4.5 | $0.00006 | $0.00208 |
Grade A, and why
hephaestus-build scanned grade A with 0 findings against 26 rules in 11 categories — prompt injection, anti-refusal, data exfiltration, privilege escalation, supply chain, agent snooping, system-prompt leakage, SSRF and excessive agency — measured 5d ago.
A static scan of the body, not an audit. Every finding is printed with the line that produced it so you can judge whether it matters here. A mod is markdown that instructs an agent; that is exactly why what it instructs is worth reading.
Nothing flagged
None of the 26 patterns this scan looks for appear in this file: no shell pipes, no recursive deletes, no credential paths, no hidden text, no instruction-override or anti-refusal phrasing, no agent-config snooping. That is not a guarantee, it is the absence of the things that are checkable.
How it starts
The opening of the file, as written. The whole thing — 157 lines — stays where its author put it; the contents beside it link to each section on GitHub.
Hephaestus Build
Procedure
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Treat this as the public Codex build surface. Do not expose or ask the user to invoke the older internal support skill names.
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Resolve the trusted engine root before reading any build contract:
ENGINE="" for candidate in \ "${CODEX_PLUGIN_ROOT:-}" \ "${CLAUDE_PLUGIN_ROOT:-}" \ "${PLUGIN_ROOT:-}" \ "$HOME/.agentlas/runtime/current/host_adapters/codex/plugins/agentlas-core-engine-meta-agent" \ "$HOME/.agentlas/runtime/current/host_adapters/claude/plugins/agentlas-core-engine-meta-agent" \ "$HOME/.agentlas/runtime/current" \ "." do if [ -n "$candidate" ] && [ -f "$candidate/AGENTS.md" ] && [ -f "$candidate/package-contract.json" ] && [ -f "$candidate/contracts/builder-interview-research-gate.md" ]; then ENGINE="$candidate" break fi done [ -n "$ENGINE" ] || { echo "Hephaestus engine not found. Run the installer first." >&2; exit 1; } RUNNER="" for candidate in "$HOME/.agentlas/runtime/current/bin/hephaestus" "$ENGINE/bin/hephaestus"; do if [ -x "$candidate" ]; then RUNNER="$candidate"; break; fi done [ -n "$RUNNER" ] || { echo "Hephaestus runner not found." >&2; exit 1; }For an interactive request whose first argument is
session, do not resolve a genericPACKAGE_TARGETand do not ask for a JSON/JSONL export. Ask first: "이 세션에서 만든 에이전트를 기본 전역 Agentlas 에이전트 폴더에 만들까요? 다른 위치를 원하면 경로를 알려주세요. 별도 위치를 지정하지 않으면 전역 폴더에 만듭니다." If no alternate location is named, useAGENTLAS_AGENT_HOMEor~/.agentlas/agentlas-agentand create a new safe-slug child package. If a destination is supplied, validate that exact folder. Never overwrite an existing child. The current conversation is the source; do not inspect recent sessions or host databases.For every other build request, take exactly one folder explicitly named or confirmed by the user as
PACKAGE_TARGET. If none was named, or multiple candidates exist, stop and ask. Never default to., the cwd, or$ENGINE. Run"$RUNNER" contract resolve-target "$PACKAGE_TARGET" --base "$PWD"and setPACKAGE_ROOTonly to the status-okreceipt's exactpackage_root. Nonzero or error receipts are blockers.
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.
- 5d ago First seen · 157 lines · 60 tokens per session scan A e8ea1c576201
hephaestus-build is a skill published in the GitHub repository agentlas-ai/Agentlas-OS (1,105 stars, last pushed 2d ago), licensed Apache-2.0. It adds 60 tokens to every session and 2,083 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 2026-09-03.
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