import { readFileSync, writeFileSync, mkdirSync } from "node:fs";
import { dirname } from "node:path";
export interface Observation {
first_seen: string;
last_seen: string;
total_recalls: number;
distinct_days: number;
contexts: string[];
promoted: boolean;
}
export interface PromotableResult {
concept: string;
score: number;
}
type ObservationMap = Record<string, Observation>;
export class ObservationStore {
private data: ObservationMap;
private readonly path: string;
constructor(path: string) {
this.path = path;
this.data = this.load();
}
record(concept: string, context: string): void {
const now = new Date().toISOString().slice(0, 10);
const existing = this.data[concept];
if (existing) {
existing.total_recalls++;
if (existing.last_seen !== now) {
existing.distinct_days++;
}
existing.last_seen = now;
if (!existing.contexts.includes(context)) {
existing.contexts.push(context);
}
} else {
this.data[concept] = {
first_seen: now,
last_seen: now,
total_recalls: 1,
distinct_days: 1,
contexts: [context],
promoted: false,
};
}
}
get(concept: string): Observation | undefined {
return this.data[concept];
}
all(): ObservationMap {
return { ...this.data };
}
score(concept: string): number {
const obs = this.data[concept];
if (!obs) return 0;
const contextDiversity = obs.contexts.length / obs.total_recalls;
const daysFactor = Math.log2(obs.distinct_days + 1);
// Recency weight: decay over 90 days
const daysSinceLastSeen = Math.max(
0,
(Date.now() - new Date(obs.last_seen).getTime()) / (1000 * 60 * 60 * 24),
);
const recencyWeight = Math.max(0.1, 1 - daysSinceLastSeen / 90);
return obs.total_recalls * daysFactor * contextDiversity * recencyWeight;
}
getPromotable(threshold: number): PromotableResult[] {
const results: PromotableResult[] = [];
for (const [concept, obs] of Object.entries(this.data)) {
if (obs.promoted) continue;
const s = this.score(concept);
if (s >= threshold) {
results.push({ concept, score: s });
}
}
return results.sort((a, b) => b.score - a.score);
}
markPromoted(concept: string): void {
const obs = this.data[concept];
if (obs) {
obs.promoted = true;
}
}
incrementDay(concept: string): void {
const obs = this.data[concept];
if (obs) {
obs.distinct_days++;
}
}
save(): void {
mkdirSync(dirname(this.path), { recursive: true });
writeFileSync(this.path, JSON.stringify(this.data, null, 2));
}
private load(): ObservationMap {
try {
const raw = readFileSync(this.path, "utf-8");
return JSON.parse(raw) as ObservationMap;
} catch {
return {};
}
}
}
