[Init] Initial commit - NetMesh terminal manager

infrastructure/ai/harness/twoPassCompaction.ts

@@ -0,0 +1,95 @@
+import type { ModelMessage } from 'ai';
+import { findSafeCompactionSplitIndex } from '../contextCompaction';
+
+interface CacheEntry {
+  modelId: string;
+  prefixLength: number;
+  fingerprint: string;
+  notePromise: Promise<string>;
+}
+
+function canonicalize(value: unknown): unknown {
+  if (Array.isArray(value)) return value.map(canonicalize);
+  if (!value || typeof value !== 'object') return value;
+  return Object.fromEntries(
+    Object.entries(value as Record<string, unknown>)
+      .sort(([left], [right]) => left.localeCompare(right))
+      .map(([key, entry]) => [key, canonicalize(entry)]),
+  );
+}
+
+export function fingerprintMessages(messages: ModelMessage[]): string {
+  const value = JSON.stringify(canonicalize(messages));
+  let hash = 0x811c9dc5;
+  for (let index = 0; index < value.length; index += 1) {
+    hash ^= value.charCodeAt(index);
+    hash = Math.imul(hash, 0x01000193);
+  }
+  return (hash >>> 0).toString(36);
+}
+
+export class TwoPassCompactionCache {
+  private readonly entries = new Map<string, CacheEntry>();
+
+  start(
+    chatSessionId: string,
+    modelId: string,
+    messages: ModelMessage[],
+    producer: (prefix: ModelMessage[]) => Promise<string>,
+  ): boolean {
+    const current = this.entries.get(chatSessionId);
+    if (
+      current
+      && current.modelId === modelId
+      && messages.length >= current.prefixLength
+      && fingerprintMessages(messages.slice(0, current.prefixLength)) === current.fingerprint
+    ) {
+      return false;
+    }
+    const protectedTail = Math.max(10, Math.ceil(messages.length * 0.05));
+    const prefixLength = findSafeCompactionSplitIndex(messages, protectedTail);
+    if (prefixLength <= 0) return false;
+    const prefix = messages.slice(0, prefixLength);
+    const fingerprint = fingerprintMessages(prefix);
+    if (
+      current
+      && current.modelId === modelId
+      && current.prefixLength === prefixLength
+      && current.fingerprint === fingerprint
+    ) {
+      return false;
+    }
+    this.entries.set(chatSessionId, {
+      modelId,
+      prefixLength,
+      fingerprint,
+      notePromise: producer(prefix).then(note => note.slice(0, 12_000)).catch(() => ''),
+    });
+    return true;
+  }
+
+  async consume(
+    chatSessionId: string,
+    modelId: string,
+    messages: ModelMessage[],
+  ): Promise<{ note: string; prefixLength: number } | undefined> {
+    const entry = this.entries.get(chatSessionId);
+    if (!entry || entry.modelId !== modelId || messages.length < entry.prefixLength) {
+      this.entries.delete(chatSessionId);
+      return undefined;
+    }
+    const prefix = messages.slice(0, entry.prefixLength);
+    if (fingerprintMessages(prefix) !== entry.fingerprint) {
+      this.entries.delete(chatSessionId);
+      return undefined;
+    }
+    const note = await entry.notePromise;
+    return note ? { note, prefixLength: entry.prefixLength } : undefined;
+  }
+
+  clear(chatSessionId: string): void {
+    this.entries.delete(chatSessionId);
+  }
+}
+
+export const globalTwoPassCompactionCache = new TwoPassCompactionCache();