gepa-ts/dist/core/engine.js

TypeScript implementation of GEPA (Gradient-free Evolution of Prompts and Agents) - Complete port with 100% feature parity

import { initializeGEPAState } from './state.js';
export class GEPAEngine {
    config;
    constructor(config) {
        if (!config.maxMetricCalls) {
            throw new Error('maxMetricCalls must be set');
        }
        this.config = {
            ...config,
            runDir: config.runDir || null,
            useWandB: config.useWandB || false,
            trackBestOutputs: config.trackBestOutputs || false,
            displayProgressBar: config.displayProgressBar || false,
            raiseOnException: config.raiseOnException !== false
        };
    }
    valEvaluator() {
        return (prog) => this.config.evaluator(this.config.valset, prog);
    }
    async runFullEvalAndAdd(newProgram, state, parentProgramIdx) {
        const numMetricCallsByDiscovery = state.totalNumEvals;
        const evalResult = this.valEvaluator()(newProgram);
        const [valsetOutputs, valsetSubscores] = evalResult instanceof Promise ?
            await evalResult : evalResult;
        const valsetScore = valsetSubscores.reduce((a, b) => a + b, 0) / valsetSubscores.length;
        state.numFullDsEvals += 1;
        state.totalNumEvals += valsetSubscores.length;
        const [newProgramIdx, linearParetoFrontProgramIdx] = state.updateStateWithNewProgram(parentProgramIdx, newProgram, valsetScore, valsetOutputs, valsetSubscores, this.config.runDir, numMetricCallsByDiscovery);
        state.fullProgramTrace[state.fullProgramTrace.length - 1].newProgramIdx = newProgramIdx;
        if (newProgramIdx === linearParetoFrontProgramIdx) {
            this.config.logger.log(`Iteration ${state.i + 1}: New program is on the linear pareto front`);
        }
        this.config.logger.log(`Iteration ${state.i + 1}: New program score: ${valsetScore.toFixed(4)} ` +
            `(improvement: ${(valsetScore - state.programFullScoresValSet[0]).toFixed(4)})`);
        return [newProgramIdx, linearParetoFrontProgramIdx];
    }
    async run() {
        if (!this.config.valset) {
            throw new Error('valset must be provided to GEPAEngine.run()');
        }
        const stateOrPromise = initializeGEPAState(this.config.runDir, this.config.seedCandidate, this.valEvaluator(), this.config.trackBestOutputs);
        const state = stateOrPromise instanceof Promise ? await stateOrPromise : stateOrPromise;
        this.config.logger.log(`Iteration ${state.i + 1}: Base program full valset score: ${state.programFullScoresValSet[0]}`);
        if (this.config.mergeProposer) {
            this.config.mergeProposer.lastIterFoundNewProgram = false;
        }
        let progressInterval = null;
        if (this.config.displayProgressBar) {
            progressInterval = setInterval(() => {
                const progress = (state.totalNumEvals / this.config.maxMetricCalls * 100).toFixed(1);
                process.stdout.write(`\rGEPA Progress: ${progress}% [${state.totalNumEvals}/${this.config.maxMetricCalls}]`);
            }, 1000);
        }
        try {
            while (state.totalNumEvals < this.config.maxMetricCalls) {
                if (!state.isConsistent()) {
                    throw new Error('State consistency check failed');
                }
                try {
                    state.save(this.config.runDir);
                    state.i += 1;
                    state.fullProgramTrace.push({ i: state.i });
                    if (this.config.mergeProposer?.useMerge &&
                        this.config.mergeProposer.mergesDue > 0 &&
                        this.config.mergeProposer.lastIterFoundNewProgram) {
                        const proposal = await this.config.mergeProposer.propose(state);
                        this.config.mergeProposer.lastIterFoundNewProgram = false;
                        if (proposal && proposal.tag === 'merge') {
                            const parentSums = proposal.subsampleScoresBefore || [Number.NEGATIVE_INFINITY, Number.NEGATIVE_INFINITY];
                            const newSum = (proposal.subsampleScoresAfter || []).reduce((a, b) => a + b, 0);
                            if (newSum >= Math.max(...parentSums)) {
                                await this.runFullEvalAndAdd(proposal.candidate, state, proposal.parentProgramIds);
                                this.config.mergeProposer.mergesDue -= 1;
                                this.config.mergeProposer.totalMergesTested += 1;
                                continue;
                            }
                            else {
                                this.config.logger.log(`Iteration ${state.i + 1}: New program subsample score ${newSum} is worse than both parents ${parentSums}, skipping merge`);
                                continue;
                            }
                        }
                    }
                    if (this.config.mergeProposer) {
                        this.config.mergeProposer.lastIterFoundNewProgram = false;
                    }
                    const proposal = await this.config.reflectiveProposer.propose(state);
                    if (!proposal) {
                        this.config.logger.log(`Iteration ${state.i + 1}: Reflective mutation did not propose a new candidate`);
                        continue;
                    }
                    const oldSum = (proposal.subsampleScoresBefore || []).reduce((a, b) => a + b, 0);
                    const newSum = (proposal.subsampleScoresAfter || []).reduce((a, b) => a + b, 0);
                    if (newSum <= oldSum) {
                        this.config.logger.log(`Iteration ${state.i + 1}: New subsample score is not better, skipping`);
                        continue;
                    }
                    await this.runFullEvalAndAdd(proposal.candidate, state, proposal.parentProgramIds);
                    if (this.config.mergeProposer) {
                        this.config.mergeProposer.lastIterFoundNewProgram = true;
                        if (this.config.mergeProposer.totalMergesTested < this.config.mergeProposer.maxMergeInvocations) {
                            this.config.mergeProposer.mergesDue += 1;
                        }
                    }
                }
                catch (error) {
                    this.config.logger.log(`Iteration ${state.i + 1}: Exception during optimization: ${error}`);
                    if (error instanceof Error) {
                        this.config.logger.log(error.stack || '');
                    }
                    if (this.config.raiseOnException) {
                        throw error;
                    }
                    else {
                        continue;
                    }
                }
            }
        }
        finally {
            if (progressInterval) {
                clearInterval(progressInterval);
                console.log('');
            }
        }
        state.save(this.config.runDir);
        return state;
    }
}
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