Evidence URL Verifier

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

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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.