glm-5.1
6016e81162
Implement the core EV calculation: EV = p*C_success + (1-p)*C_fail where C_success = scopeCost*impactWeight, C_fail = scopeCost*impactWeight + fallbackCost + timeLost*expectedRetries. - expectedRetries = (1-p)/p when p>0, else 0 (geometric series) - Caps expectedRetries at config.retries when retries > 0 - Multiplies final EV by config.valueRate when non-zero - 30 unit tests covering formula, edge cases, and Python research model values
60 lines
2.0 KiB
TypeScript
60 lines
2.0 KiB
TypeScript
import type { EvConfig, EvResult } from "../schema/results.js";
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/**
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* Calculate the expected value (EV) of a task.
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*
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* Pure math function — takes numeric inputs, returns EV result.
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* No graph dependency.
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*
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* Formula:
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* expectedRetries = (1 - p) / p when p > 0, else 0 (geometric series)
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* C_success = scopeCost * impactWeight
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* C_fail = scopeCost * impactWeight + fallbackCost + timeLost * expectedRetries
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* EV = p * C_success + (1 - p) * C_fail
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*
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* When `config.retries` is provided and > 0, `expectedRetries` is capped at `retries`.
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* When `config.valueRate` is non-zero, the final EV is multiplied by `valueRate`.
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*
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* @param p - Probability of success (0 to 1)
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* @param scopeCost - Cost estimate from scope (1.0–5.0)
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* @param impactWeight - Impact weight (1.0–3.0)
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* @param config - Optional configuration: retries, fallbackCost, timeLost, valueRate
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* @returns EvResult with ev, pSuccess, and expectedRetries
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*/
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export function calculateTaskEv(
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p: number,
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scopeCost: number,
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impactWeight: number,
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config?: EvConfig,
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): EvResult {
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const retries = config?.retries ?? 0;
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const fallbackCost = config?.fallbackCost ?? 0;
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const timeLost = config?.timeLost ?? 0;
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const valueRate = config?.valueRate ?? 0;
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// Expected retries: geometric series (1-p)/p when p > 0
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let expectedRetries = p > 0 ? (1 - p) / p : 0;
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// Cap at configured max retries when retries > 0
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if (retries > 0 && expectedRetries > retries) {
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expectedRetries = retries;
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}
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// C_success and C_fail: impactWeight scales scopeCost
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const cSuccess = scopeCost * impactWeight;
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const cFail = scopeCost * impactWeight + fallbackCost + timeLost * expectedRetries;
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// EV = P_success * C_success + (1 - P_success) * C_fail
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let ev = p * cSuccess + (1 - p) * cFail;
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// Apply value rate conversion when configured
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if (valueRate !== 0) {
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ev = ev * valueRate;
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}
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return { ev, pSuccess: p, expectedRetries };
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}
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// Placeholder for future implementation
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// export function workflowCost(...) { ... }
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// export function computeEffectiveP(...) { ... }
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