feat(server): add institutional memory recall

- File-based memory under .boocode/memory/ (project/user/reference topics)
- Hierarchical 4-scope scan: global → home → project → session
- Keyword/tag relevance matching for query-based recall
- Injected as <boocode-memory> block in system prompt at assembly
- v1 recall-only (extract/dream deferred to v2)

apps/server/src/services/memory/scan.ts

@@ -0,0 +1,72 @@
+import { homedir } from 'node:os';
+import { join } from 'node:path';
+import { readFile, readdir } from 'node:fs/promises';
+import type { MemoryEntry } from './entries.js';
+import { parseMemoryEntries } from './entries.js';
+import { getMemoryRoot } from './paths.js';
+
+export interface MemoryScope {
+  projectRoot: string;
+  sessionDir?: string;
+  homeDir?: string;
+}
+
+async function scanDirectory(dir: string): Promise<MemoryEntry[]> {
+  const entries: MemoryEntry[] = [];
+  try {
+    const files = await readdir(dir, { withFileTypes: true });
+    for (const file of files) {
+      if (file.isFile() && file.name.endsWith('.md')) {
+        const content = await readFile(join(dir, file.name), 'utf8');
+        entries.push(...parseMemoryEntries(file.name, content));
+      }
+    }
+  } catch {
+    // Directory doesn't exist
+  }
+  return entries;
+}
+
+const MEMORY_TOPICS = ['project', 'user', 'reference'] as const;
+
+async function scanTopicDirs(root: string): Promise<MemoryEntry[]> {
+  const entries: MemoryEntry[] = [];
+  for (const topic of MEMORY_TOPICS) {
+    entries.push(...(await scanDirectory(join(root, topic))));
+  }
+  return entries;
+}
+
+export async function scanMemoryScopes(scope: MemoryScope): Promise<MemoryEntry[]> {
+  const allEntries: MemoryEntry[] = [];
+
+  // 1. Global (~/.boocode/memory/) - lowest priority
+  allEntries.push(...(await scanTopicDirs(getMemoryRoot(homedir()))));
+
+  // 2. Home ($HOME/.boocode/memory)
+  const homeDir = scope.homeDir ?? homedir();
+  const homeRoot = getMemoryRoot(homeDir);
+  if (homeRoot !== getMemoryRoot(homedir())) {
+    allEntries.push(...(await scanTopicDirs(homeRoot)));
+  }
+
+  // 3. Project (.boocode/memory/ under project root)
+  allEntries.push(...(await scanTopicDirs(getMemoryRoot(scope.projectRoot))));
+
+  // 4. Session (.boocode/sessions/<id>/memory.md) - highest priority
+  if (scope.sessionDir) {
+    try {
+      const sessionFile = join(scope.sessionDir, 'memory.md');
+      const content = await readFile(sessionFile, 'utf8');
+      allEntries.push(...parseMemoryEntries('session-memory', content));
+    } catch {
+      // No session memory file
+    }
+  }
+
+  return allEntries;
+}
+
+export async function scanProjectMemory(projectRoot: string): Promise<MemoryEntry[]> {
+  return scanMemoryScopes({ projectRoot });
+}