float luminance(float3 color)
{
    return dot(color, float3(0.2126, 0.7152, 0.0722));
}

float currentResetPhase(float timeSeconds, float resetInterval)
{
    float safeInterval = max(resetInterval, 0.001);
    float cycleIndex = floor(timeSeconds / safeInterval);
    return frac(cycleIndex * 0.5) >= 0.5 ? 1.0 : 0.0;
}

float4 shadeVideo(ShaderContext context)
{
    float safeResetSeconds = max(resetSeconds, 0.001);
    float phase = currentResetPhase(context.time, safeResetSeconds);

    float4 previousFeedback = sampleFeedback(context.uv);
    bool phaseMatches = context.feedbackAvailable > 0 && abs(previousFeedback.a - phase) < 0.25;
    float3 previousAccumulation = phaseMatches ? previousFeedback.rgb : float3(0.0, 0.0, 0.0);

    float currentLuma = luminance(context.sourceColor.rgb);
    float thresholdWidth = max(softness, 0.0001);
    float brightMask = smoothstep(highlightThreshold - thresholdWidth, highlightThreshold + thresholdWidth, currentLuma);

    float3 currentContribution = context.sourceColor.rgb * brightMask * max(accumulateAmount, 0.0);
    float3 nextAccumulation = saturate(previousAccumulation + currentContribution);

    float3 displayColor = context.sourceColor.rgb * saturate(baseMix) + nextAccumulation * max(displayGain, 0.0);
    return float4(saturate(displayColor), phase);
}