Trailblaze is a UI testing framework that lets coding agents control iOS, Android, and web devices through natural-language actions, then save those sessions as replayable test trails. It is for teams testing device-based user flows, with recorded actions that CI can replay without an LLM. The catalogue skills teach agents how to drive devices, save and replay trails, and create custom tools.
Getting it into your agent
It runs from inside its repository, so the clone comes first — what it calls does not travel with the file alone.
git clone --depth 1 https://github.com/block/trailblazenpx agentmods add skills/block/trailblaze/trailblaze-validate-oobWrote 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/block/trailblaze/trailblaze-validate-oob)<a href="https://agentmods.dev/skills/block/trailblaze/trailblaze-validate-oob"><img src="https://agentmods.dev/badge/skills/block/trailblaze/trailblaze-validate-oob.svg" alt="Measured on agentmods" 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 | $0.00112 | $0.02163 |
| Opus 5 | $0.00056 | $0.01081 |
| Sonnet 5 | $0.00022 | $0.00433 |
| Haiku 4.5 | $0.00011 | $0.00216 |
Grade A, and why
trailblaze-validate-oob 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 8d 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 — 218 lines — stays where its author put it; the contents beside it link to each section on GitHub.
Validating Trailblaze's out-of-box experience
This skill encodes the methodology for honestly evaluating whether Trailblaze's user-facing CLI matches what a fresh agent / new user would intuitively expect. It's the framework's own UX regression test, run by an agent simulating cold-start use.
The goal is to catch counter-intuitive defaults, broken claims in the
trailblaze skill, and friction that the team has gone CLI-blind on.
When to run a validation pass
- After any change to the
trailblazeCLI surface (commands, flags, default behavior) - After any change to the
trailblazeClaude skill (the siblingtrailblaze/SKILL.md) or its references - Periodically (monthly?) even with no changes, to catch drift
- When a new rung of the adoption ladder gets added to the skill
What "good" looks like
After a validation pass, a fresh agent following only the
trailblaze skill should be able to complete the scenario with zero
surprises. Specifically:
- Every command the skill says to run actually exists with the documented flags and argument shape
- Every output the skill describes matches what the CLI actually prints
- The basic loop (drive → save → replay → inspect) works end-to-end with no undocumented gotchas
- Failure modes the skill mentions are real failure modes; the recovery steps actually recover
- Errors the user might hit have clear
hint:lines pointing at the fix - No "workaround" paragraphs in the skill that exist to paper over CLI behavior the user wouldn't naturally guess
If the validation surfaces something the agent couldn't have guessed from the skill alone, that's either a skill update OR a CLI fix — and the latter is usually preferable.
Methodology
Step 1: Install the binary fresh
Use the actual end-user install path, NOT ./trailblaze from the
repo (which goes through Gradle on every call and isn't what users
hit):
./scripts/install-trailblaze-source.sh
The script builds the uber JAR and installs it under
~/.trailblaze/install/ with a symlink onto the system PATH. The
specific symlink location depends on your platform (homebrew on
macOS, /usr/local/bin/ on Intel macs / Linux, …) — defer to the
script's stdout for the exact path rather than memorizing one. Then
verify:
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.
- 8d ago First seen · 218 lines · 112 tokens per session scan A 4f8180547336
trailblaze-validate-oob is a skill published in the GitHub repository block/trailblaze (310 stars, last pushed 5d ago), licensed Apache-2.0. It adds 112 tokens to every session and 2,163 once invoked, about $0.0006 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 2026-08-30.
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