fix(core): add missing llmAdapter module for build

packages/core/src/index.ts exports ./llmAdapter but the file was never
tracked; CI failed with 'Could not resolve ./llmAdapter'.

Author: betterdataco

packages/core/src/llmAdapter.ts

@@ -0,0 +1,104 @@
+// @license Apache-2.0
+// SPDX-License-Identifier: Apache-2.0
+
+/**
+ * Multi-LLM adapter contract for Loop Engine state-machine steps.
+ * Provider packages (e.g. `@loop-engine/adapter-perplexity`) implement this interface.
+ */
+
+export interface AdapterInput {
+  prompt: string;
+  systemPrompt?: string;
+  model?: string;
+  maxTokens?: number;
+  temperature?: number;
+  metadata?: AdapterInputMetadata;
+}
+
+export type SearchRecencyFilter = "month" | "week" | "day" | "hour";
+
+export interface AdapterInputMetadata extends Record<string, unknown> {
+  searchDomainFilter?: string[];
+  searchRecencyFilter?: SearchRecencyFilter;
+  returnCitations?: boolean;
+  returnImages?: boolean;
+}
+
+export interface AdapterOutput {
+  text: string;
+  model: string;
+  usage: {
+    promptTokens: number;
+    completionTokens: number;
+  };
+}
+
+export interface AdapterChunk {
+  delta: string;
+  done?: boolean;
+}
+
+export interface LLMAdapter {
+  name: string;
+  invoke(input: AdapterInput): Promise<AdapterOutput>;
+  stream?(input: AdapterInput): AsyncIterable<AdapterChunk>;
+  guardEvidence(payload: unknown): unknown;
+}
+
+export interface GuardEvidenceOptions {
+  /** Object keys to omit entirely (case-insensitive match). */
+  stripFields?: string[];
+  /** Regexes applied to string values to mask secrets (e.g. API key patterns). */
+  maskPatterns?: RegExp[];
+}
+
+function normalizeKey(key: string): string {
+  return key.toLowerCase();
+}
+
+/**
+ * Deep-redact payloads before logging or persisting to an audit trail.
+ * Strips configured keys and masks matching substrings in strings.
+ */
+export function guardEvidence(payload: unknown, options?: GuardEvidenceOptions): unknown {
+  const strip = new Set((options?.stripFields ?? []).map(normalizeKey));
+  const masks = options?.maskPatterns ?? [];
+
+  const walk = (value: unknown): unknown => {
+    if (value === null || value === undefined) {
+      return value;
+    }
+    if (typeof value === "string") {
+      let s = value;
+      for (const pattern of masks) {
+        s = s.replace(pattern, "[REDACTED]");
+      }
+      return s;
+    }
+    if (typeof value === "number" || typeof value === "boolean") {
+      return value;
+    }
+    if (typeof value === "bigint") {
+      return value;
+    }
+    if (value instanceof Date) {
+      return value;
+    }
+    if (Array.isArray(value)) {
+      return value.map((item) => walk(item));
+    }
+    if (typeof value === "object") {
+      const out: Record<string, unknown> = {};
+      for (const [k, v] of Object.entries(value as Record<string, unknown>)) {
+        if (strip.has(normalizeKey(k))) {
+          continue;
+        }
+        out[k] = walk(v);
+      }
+      return out;
+    }
+    return value;
+  };
+
+  return walk(payload);
+}