evidence-url-verifier

name	evidence-url-verifier
description	Verify evidence URLs are real and accessible. Check that artifact links resolve to actual content, not placeholders.

Evidence URL Verifier

Verify evidence URLs are real and accessible.

Problem

Evidence links often:

• Point to non-existent resources
• Are placeholders (example.com)
• Expire or get deleted
• Don't match claimed content

Workflow

1. URL Validation

function Test-EvidenceUrl {
    param([string]$url)
    
    try {
        $response = Invoke-WebRequest -Uri $url -Method Head -TimeoutSec 10
        return @{
            Valid = $true
            Status = $response.StatusCode
            ContentType = $response.ContentType
        }
    } catch {
        return @{
            Valid = $false
            Error = $_.Exception.Message
        }
    }
}

# Usage
$result = Test-EvidenceUrl "https://example.com/artifact"
if ($result.Valid) {
    Write-Host "URL valid: $($result.Status)"
} else {
    Write-Error "URL invalid: $($result.Error)"
}

2. Content Verification

# Check URL matches claimed content type
$response = Invoke-WebRequest -Uri $url
if ($response.ContentType -notlike "text/*" -and $expectedType -eq "text") {
    Write-Warning "Content type mismatch"
}

# Check for placeholder text
$content = $response.Content
if ($content -match "lorem ipsum|placeholder|example") {
    Write-Warning "Content appears to be placeholder"
}

3. Artifact Existence

# For local paths
if (Test-Path $artifactPath) {
    $size = (Get-Item $artifactPath).Length
    if ($size -eq 0) {
        Write-Warning "Artifact file is empty"
    }
} else {
    Write-Error "Artifact not found: $artifactPath"
}

Executable Completion Criteria

Criteria	Verification
URL resolves	HTTP 200 response
Content matches	Type matches expected
No placeholders	Content is substantive
Local paths exist	Test-Path returns true

Privacy/Safety

• Don't log full URL contents
• Redact sensitive data in responses
• Respect rate limits (max 1 req/sec)

Self-Use Trigger

Use when:

• Task claims evidence artifact
• URL provided as proof
• Before marking task complete
• Audit of past completions

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Verify evidence. Trust but confirm.