feat(agent): opt-in tool-result context pruning

src/agents/pi-extensions/context-pruning/tools.ts

@@ -0,0 +1,46 @@
+import type { ContextPruningToolMatch } from "./settings.js";
+
+function normalizePatterns(patterns?: string[]): string[] {
+  if (!Array.isArray(patterns)) return [];
+  return patterns.map((p) => String(p ?? "").trim()).filter(Boolean);
+}
+
+type CompiledPattern =
+  | { kind: "all" }
+  | { kind: "exact"; value: string }
+  | { kind: "regex"; value: RegExp };
+
+function compilePattern(pattern: string): CompiledPattern {
+  if (pattern === "*") return { kind: "all" };
+  if (!pattern.includes("*")) return { kind: "exact", value: pattern };
+
+  const escaped = pattern.replace(/[.*+?^${}()|[\]\\]/g, "\\$&");
+  const re = new RegExp(`^${escaped.replaceAll("\\*", ".*")}$`);
+  return { kind: "regex", value: re };
+}
+
+function compilePatterns(patterns?: string[]): CompiledPattern[] {
+  return normalizePatterns(patterns).map(compilePattern);
+}
+
+function matchesAny(toolName: string, patterns: CompiledPattern[]): boolean {
+  for (const p of patterns) {
+    if (p.kind === "all") return true;
+    if (p.kind === "exact" && toolName === p.value) return true;
+    if (p.kind === "regex" && p.value.test(toolName)) return true;
+  }
+  return false;
+}
+
+export function makeToolPrunablePredicate(
+  match: ContextPruningToolMatch,
+): (toolName: string) => boolean {
+  const deny = compilePatterns(match.deny);
+  const allow = compilePatterns(match.allow);
+
+  return (toolName: string) => {
+    if (matchesAny(toolName, deny)) return false;
+    if (allow.length === 0) return true;
+    return matchesAny(toolName, allow);
+  };
+}