Module budget 

Render budget enforcement with graceful degradation.

This module provides time-based budget tracking for frame rendering, enabling the system to gracefully degrade visual fidelity when performance budgets are exceeded.

Overview

Agent UIs receive unpredictable content (burst log output, large tool responses). A frozen UI during burst input makes the agent feel broken. Users tolerate reduced visual fidelity; they do NOT tolerate hangs.

Usage

use ftui_render::budget::{RenderBudget, DegradationLevel, FrameBudgetConfig};
use std::time::Duration;

// Create a budget with 16ms total (60fps target)
let mut budget = RenderBudget::new(Duration::from_millis(16));

// Check remaining time
let remaining = budget.remaining();

// Check if we should degrade for an expensive operation
if budget.should_degrade(Duration::from_millis(5)) {
    budget.degrade();
}

// Render at current degradation level
match budget.degradation() {
    DegradationLevel::Full => { /* full rendering */ }
    DegradationLevel::SimpleBorders => { /* ASCII borders */ }
    _ => { /* further degradation */ }
}

Structs

BudgetController

Adaptive budget controller combining PID regulation with e-process gating.

BudgetControllerConfig

Configuration for the adaptive budget controller.

BudgetTelemetry

Snapshot of budget controller telemetry for diagnostics and debug overlay.

EProcessConfig

Anytime-valid e-process for gating degradation decisions.

FrameBudgetConfig

Configuration for frame budget behavior.

PhaseBudgets

Per-phase time budgets within a frame.

PidGains

PID controller gains for frame time regulation.

RenderBudget

Render time budget with graceful degradation.

Enums

BudgetDecision

Decision output from the budget controller.

DegradationLevel

Progressive degradation levels for render quality.

Phase

Render phases for budget allocation.