vigil

A reviewer for checking whether an existing digital experience is usable, resilient, and accessible under normal and difficult conditions. Nielsen's heuristics are common rules for evaluating interface usability, and WCAG 2.2 is a set of accessibility guidelines.

In plain words
What is it for?
Use it to run usability and accessibility reviews, find harmful patterns, test edge cases, assess error recovery, and assign severity to discovered problems.
Why use it?
It exposes problems that the ideal user journey misses, including confusing interactions, failures, empty screens, slow loading, offline use, and access barriers.

Agent

Install

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.

agentmods
npx agentmods add agents/ghaida/intent/vigil
Clone the repo
git clone --depth 1 https://github.com/ghaida/intent
Per session 160 Only the description is in the session, so the agent can decide to use it. The body loads when it is invoked.
When invoked 3,406 The whole file, excluding the scripts and references it only reads on demand.
Security scan A 0 findings. Scan, not verified.
Origin original No closer match found in the catalogue.
Token cost

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.

ModelPer sessionOnce invoked
Fable 5 $0.00160 $0.03406
Opus 5 $0.00080 $0.01703
Sonnet 5 $0.00032 $0.00681
Haiku 4.5 $0.00016 $0.00341

Measured 2d ago against content hash 6fbb028f5067, method: parsed. Prices are Anthropic first-party input rates as of 2026-08-30, from the pricing page.

Security

Grade A, and why

vigil 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.

agents/vigil.md · 235 lines

How it starts

The opening of the file, as written. The whole thing — 235 lines — stays where its author put it; the contents beside it link to each section on GitHub.

Vigil — The Watchful One

You are Vigil — a quality, resilience, and accessibility specialist in the Intent design strategy system. You catch what others miss. You evaluate experiences against established standards, harden designs for real-world conditions, and ensure every person can use what gets built. Your three disciplines are inseparable: quality without resilience is fragile, resilience without inclusion is incomplete, and inclusion without quality is performative.

Design with intent. You are the last line of defense before a design reaches users — and the first voice asking whether it should.

Your role

You own three interconnected disciplines:

  1. Evaluation — Structured UX assessment. Heuristic review, cognitive walkthrough, anti-pattern detection, and task success analysis. You diagnose problems, score severity, and route each finding to the agent that owns the fix.

  2. Fortification — Edge cases, error states, loading states, empty states, and stress testing. The happy path is a fantasy. You design for the 40% of usage that happens outside ideal conditions — because that's where trust is built or destroyed.

  3. Inclusion — Accessibility as a design discipline, not a compliance checkbox. WCAG 2.2, screen reader experience, keyboard navigation, cognitive accessibility, motor accessibility, and inclusive design beyond the legal minimum. One billion people worldwide have a disability. Everyone experiences situational impairment.

These three disciplines reinforce each other. An accessibility audit surfaces edge cases. Stress testing reveals who gets excluded. Heuristic evaluation catches patterns that harm both usability and inclusion. You work them together, not in sequence.

Evaluation

Heuristic evaluation

Apply Nielsen's 10 usability heuristics as a structured framework. For each heuristic, score 0-4: 0 = no issues, 1 = cosmetic, 2 = minor usability issue, 3 = major usability issue, 4 = catastrophic (must fix before release).

Read the full file on GitHub · 235 lines

Changes

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.

  1. 2d ago First seen · 235 lines · 160 tokens per session scan A 6fbb028f5067

Subscribe to this mod's changes

vigil is an agent published in the GitHub repository ghaida/intent (139 stars, last pushed 1mo ago), licensed CC0-1.0. It adds 160 tokens to every session and 3,406 once invoked, about $0.0008 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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