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 agentmods add commands/vyuh-labs/dxkit/setup-prebuildgit clone --depth 1 https://github.com/vyuh-labs/dxkitWhat 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 | $0.00000 | $0.01174 |
| Opus 5 | $0.00000 | $0.00587 |
| Sonnet 5 | $0.00000 | $0.00235 |
| Haiku 4.5 | $0.00000 | $0.00117 |
Grade A, and why
setup-prebuild 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 2d 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 — 112 lines — stays where its author put it; the contents beside it link to each section on GitHub.
vyuh-dxkit setup-prebuild
Configure GitHub Codespaces prebuilds for the repo so fresh Codespaces start from a prebuilt image instead of re-running the full devcontainer build.
Why an automation CLI
dxkit's polyglot devcontainer takes ~7 min cold-start (post per-stack feature work in 2.5.1). Prebuilds drop this to ~30s by maintaining the built image in GitHub's image cache.
The math is overwhelming for any team using Codespaces:
| Cost | Saved per dev per week (5 fresh Codespaces) |
|---|---|
| ~$3-5/month prebuild storage per region | ~30 min of wall-clock wait time |
| For a 20-dev team: ~$60-100/month | ~200 hours of dev time per year per team |
Manually configuring Codespaces prebuilds is a UI dance through repo Settings → Codespaces → Set up prebuild → configure branches → wait for first prebuild. Many teams skip it — and pay the ~7 min cold- start cost on every fresh Codespaces session.
This CLI automates the configuration in one command.
Usage
# Default: prebuild the repo's default branch in GitHub's chosen region
vyuh-dxkit setup-prebuild
# Specify a branch other than the default
vyuh-dxkit setup-prebuild --branch develop
# Pin specific regions (comma-separated GitHub region IDs)
vyuh-dxkit setup-prebuild --regions westus2,eastus
# Force re-create even if a prebuild config exists for the branch
vyuh-dxkit setup-prebuild --force
Flags
| Flag | Effect |
|---|---|
--branch <name> |
Branch to prebuild. Default: the repo's default branch. |
--regions <r> |
Comma-separated GitHub region IDs (e.g. westus2,eastus). Default: omit — GitHub picks based on the org's Codespaces preferences. |
--force |
Re-create the prebuild config even if one already exists for the branch. Default: skip (idempotent; avoids clobbering customer-chosen regions). |
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.
- 2d ago First seen · 112 lines · 0 tokens per session scan A 42309394bd83
setup-prebuild is a command published in the GitHub repository vyuh-labs/dxkit (10 stars, last pushed 4d ago), licensed MIT. It costs nothing until one of its globs matches a file; then it loads 1,174 tokens. 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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