wehub-resource-sync
73 lines
2.8 KiB
TypeScript
73 lines
2.8 KiB
TypeScript
import type { CompressionConfig, PreserveSystemPromptMode } from "./types.ts";
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/**
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* T05/C5 — system-prompt preservation mode.
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*
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* The engine-facing field is the boolean `CompressionConfig.preserveSystemPrompt`
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* (truthy = skip/preserve the system prompt). Its authoritative *intent* is the
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* `preserveSystemPromptMode` enum, resolved to that boolean at the cache-aware layer
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* (`resolveCacheAwareConfig`), which already runs upstream in `chatCore` with the
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* caching context. This module is the single source of the enum<->boolean mapping so
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* the legacy boolean and the new enum can never drift.
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*
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* Mode semantics:
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* - `always` → preserve the system prompt unconditionally.
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* - `whenNoCache` → preserve it only when there is a cache to protect (provider caches
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* the prefix or `cache_control` is present); compress it otherwise.
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* This is exactly what the legacy `preserveSystemPrompt: false` already
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* did via the #3890/#3955 cache guard.
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* - `never` → compress the system prompt even when it breaks a prompt cache.
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*/
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export const PRESERVE_SYSTEM_PROMPT_MODES: readonly PreserveSystemPromptMode[] = [
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"always",
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"whenNoCache",
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"never",
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];
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export function isPreserveSystemPromptMode(value: unknown): value is PreserveSystemPromptMode {
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return (
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typeof value === "string" &&
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(PRESERVE_SYSTEM_PROMPT_MODES as readonly string[]).includes(value)
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);
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}
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/**
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* Back-compat shim: derive the authoritative mode from a config. An explicit
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* `preserveSystemPromptMode` always wins; otherwise the legacy boolean is mapped
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* 1:1 to the behaviour it already had (`false → whenNoCache`, anything else → `always`).
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*/
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export function normalizePreserveSystemPromptMode(
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config: Pick<CompressionConfig, "preserveSystemPrompt" | "preserveSystemPromptMode">
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): PreserveSystemPromptMode {
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if (isPreserveSystemPromptMode(config.preserveSystemPromptMode)) {
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return config.preserveSystemPromptMode;
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}
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return config.preserveSystemPrompt === false ? "whenNoCache" : "always";
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}
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/**
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* Resolve a mode to the effective engine-facing boolean given whether a cacheable
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* prefix is present. `true` = preserve (skip), `false` = compress the system prompt.
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*/
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export function resolvePreserveSystemPrompt(
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mode: PreserveSystemPromptMode,
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{ hasCache }: { hasCache: boolean }
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): boolean {
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switch (mode) {
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case "always":
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return true;
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case "never":
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return false;
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case "whenNoCache":
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return hasCache;
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}
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}
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/**
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* The no-cache projection of a mode — the stored/effective boolean used as a sane
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* default for any reader that runs before the cache-aware layer materializes it.
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*/
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export function modeToBaselineBoolean(mode: PreserveSystemPromptMode): boolean {
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return resolvePreserveSystemPrompt(mode, { hasCache: false });
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}
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