chore: import upstream snapshot with attribution

2026-07-13 13:39:12 +08:00
commit d8dcd5f6d1
8604 changed files with 2479390 additions and 0 deletions
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+import type { ContextBudgetConfig, ContextBudgetPolicy } from "./types.ts";
+
+/**
+ * Pure target-token computation (design D-C1). No clock, no DB, no tokenizer.
+ *
+ * @param policy            active target policy
+ * @param modelContextLimit the resolved upstream model's context window (impure caller looks it up)
+ * @param requestMaxTokens  request.max_tokens, if the client sent one (reserve-output only)
+ * @param config            reserves / margin / pct / absoluteBudget
+ * @returns the maximum prompt-token target the compressed request should fit within
+ */
+export function computeTarget(
+  policy: ContextBudgetPolicy,
+  modelContextLimit: number,
+  requestMaxTokens: number | null,
+  config: Pick<ContextBudgetConfig, "outputReserve" | "safetyMargin" | "pct" | "absoluteBudget">
+): number {
+  if (policy === "absolute") {
+    return Math.max(0, Math.floor(config.absoluteBudget));
+  }
+  if (policy === "percentage") {
+    const pct = config.pct > 0 && config.pct <= 1 ? config.pct : 1;
+    return Math.max(0, Math.floor(modelContextLimit * pct));
+  }
+  // reserve-output (default): limit − output reservation − safety margin.
+  const reserve =
+    typeof requestMaxTokens === "number" && requestMaxTokens > 0
+      ? requestMaxTokens
+      : config.outputReserve;
+  return Math.max(0, Math.floor(modelContextLimit - reserve - config.safetyMargin));
+}