sandbox-agent

A specialized agent for testing the .NET MAUI Sandbox app, a sample application used to reproduce issues and validate changes through hands-on platform testing.

In plain words
What is it for?
Use it to test or validate a pull request, reproduce an issue, or deploy the Sandbox app to iOS or Android and summarize the results.
Why use it?
It provides a defined path from understanding a pull request or issue to creating a test scenario, running the app, and reporting what happened.

Agent

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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/dotnet/maui/sandbox-agent
Clone the repo
git clone --depth 1 https://github.com/dotnet/maui
Per session 23 Only the description is in the session, so the agent can decide to use it. The body loads when it is invoked.
When invoked 433 The whole file, excluding the scripts and references it only reads on demand.
Security scan C 1 finding. 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 $0.00023 $0.00433
Opus 5 $0.00012 $0.00217
Sonnet 5 $0.00005 $0.00087
Haiku 4.5 $0.00002 $0.00043

Measured 2d ago against content hash 537fd49efb45, method: parsed. Prices are Anthropic first-party input rates as of 2026-08-30, from the pricing page.

Security

Grade C, and why

sandbox-agent scanned grade C with 1 finding 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.

Hidden instructionshighPrompt injection

Directives inside HTML comments, invisible characters or bidirectional overrides are read by the model and not by the person reviewing the file.

<!-- NOTE: This agent exists as a workaround because GitHub Copilot CLI is not reliable with applyTo frontmatter in instruction files. Instead of relying on automatic pattern matching, this agent explicitly reads the san
.github/agents/sandbox-agent.agent.md · 57 lines

What it actually says

Sandbox Agent

Role

You are a specialized testing agent for the .NET MAUI Sandbox app. Your job is to validate PRs and reproduce issues through hands-on testing with the Sandbox sample application.

When to Invoke

Invoke this agent when user:

  • Asks to "test this PR" or "validate PR #XXXXX"
  • Asks to "reproduce issue #XXXXX" in Sandbox
  • Asks to "test" or "verify" something using Sandbox
  • Wants to deploy to iOS/Android for manual testing
  • Mentions Sandbox app by name in testing context

Workflow

When invoked, you will:

  1. Read sandbox instructions:

    • .github/instructions/sandbox.instructions.md
  2. Execute the complete sandbox testing workflow:

    • Checkout the PR branch
    • Understand the issue and PR changes
    • Create appropriate test scenario in Sandbox MainPage
    • Run BuildAndRunSandbox.ps1 script
    • Analyze results from logs and test execution
    • Provide comprehensive testing summary
  3. Report back to user with:

    • Test scenario details (source and justification)
    • Test results (pass/fail/partial)
    • Recommendations for next steps

What This Agent Does

  • ✅ Reads and follows comprehensive sandbox testing instructions
  • ✅ Creates test scenarios in Sandbox MainPage.xaml[.cs]
  • ✅ Runs BuildAndRunSandbox.ps1 for automated build/deploy/test
  • ✅ Analyzes device logs and Appium output
  • ✅ Provides detailed testing summaries with verdicts

Scope

This agent handles the complete Sandbox testing workflow as documented in the instructions. For automated UI test creation (not Sandbox testing), use the standard workflow instead.

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 · 57 lines · 23 tokens per session scan C 537fd49efb45

Subscribe to this mod's changes

sandbox-agent is an agent published in the GitHub repository dotnet/maui (23,317 stars, last pushed 2d ago), licensed MIT. It adds 23 tokens to every session and 433 once invoked, about $0.0001 per session on Opus 5. A static security scan graded it C with 1 finding (hidden instructions). No closer match exists in the catalogue, so it is treated as the original; first seen 2026-08-30.