diff --git a/.env.example b/.env.example
index c7e4911e4a..24d396f050 100644
--- a/.env.example
+++ b/.env.example
@@ -1311,3 +1311,12 @@ APP_LOG_TO_FILE=true
 # ELECTRON_SMOKE_DATA_DIR=
 # ELECTRON_SMOKE_KEEP_DATA=0
 # ELECTRON_SMOKE_STREAM_LOGS=0
+
+# Memory engine (plan 21)
+# MEMORY_EMBEDDING_CACHE_TTL_MS=300000          # default 5 min
+# MEMORY_EMBEDDING_CACHE_MAX=1000               # default 1000 entries
+# MEMORY_TRANSFORMERS_MODEL=Xenova/all-MiniLM-L6-v2
+# MEMORY_STATIC_MODEL=minishlab/potion-base-8M  # HF repo id (download once)
+# MEMORY_STATIC_CACHE_DIR=                      # default <DATA_DIR>/embeddings
+# MEMORY_VEC_TOP_K=20                           # default top-K for vector search
+# MEMORY_RRF_K=60                               # RRF k constant (sqlite-vec hybrid recipe)
diff --git a/src/lib/db/memoryVec.ts b/src/lib/db/memoryVec.ts
new file mode 100644
index 0000000000..c0025bfa99
--- /dev/null
+++ b/src/lib/db/memoryVec.ts
@@ -0,0 +1,138 @@
+/**
+ * db/memoryVec.ts — CRUD for memory vector metadata and reindex state.
+ *
+ * Plan 21 — Memory Engine Redesign.
+ * Raw SQL is allowed here (Hard Rule #5 — src/lib/db/ domain module).
+ *
+ * This module manages:
+ *   - `memory_vec_meta`: singleton row tracking the active embedding dim/signature/reset
+ *   - `memories.needs_reindex`: flag for lazy backfill of missing/stale vectors
+ */
+
+import { getDbInstance } from "./core";
+
+// ──────────────── Types ────────────────
+
+export interface MemoryVecMeta {
+  activeDim: number | null;
+  embeddingSignature: string | null;
+  lastResetAt: string | null;
+  vecLoaded: boolean;
+}
+
+// ──────────────── memory_vec_meta ────────────────
+
+/**
+ * Get the singleton memory_vec_meta row.
+ * Returns defaults if the row is absent (e.g. migration not yet applied on
+ * an in-memory test DB that ran without the migration file).
+ */
+export function getMemoryVecMeta(): MemoryVecMeta {
+  const db = getDbInstance();
+  const row = db
+    .prepare(
+      "SELECT active_dim, embedding_signature, last_reset_at, vec_loaded FROM memory_vec_meta WHERE id = 1"
+    )
+    .get() as
+    | {
+        active_dim: number | null;
+        embedding_signature: string | null;
+        last_reset_at: string | null;
+        vec_loaded: number;
+      }
+    | undefined;
+
+  if (!row) {
+    return {
+      activeDim: null,
+      embeddingSignature: null,
+      lastResetAt: null,
+      vecLoaded: false,
+    };
+  }
+
+  return {
+    activeDim: row.active_dim,
+    embeddingSignature: row.embedding_signature,
+    lastResetAt: row.last_reset_at,
+    vecLoaded: row.vec_loaded === 1,
+  };
+}
+
+/**
+ * Update one or more fields in the singleton memory_vec_meta row.
+ * Uses INSERT OR REPLACE to handle the case where the row is missing
+ * (e.g. called before or during migration on a test DB).
+ */
+export function setMemoryVecMeta(meta: Partial<MemoryVecMeta>): void {
+  const db = getDbInstance();
+
+  // Read current values first so we can merge (partial update pattern).
+  const current = getMemoryVecMeta();
+
+  const activeDim = "activeDim" in meta ? meta.activeDim ?? null : current.activeDim;
+  const embeddingSignature =
+    "embeddingSignature" in meta
+      ? meta.embeddingSignature ?? null
+      : current.embeddingSignature;
+  const lastResetAt =
+    "lastResetAt" in meta ? meta.lastResetAt ?? null : current.lastResetAt;
+  const vecLoaded =
+    "vecLoaded" in meta ? (meta.vecLoaded ? 1 : 0) : current.vecLoaded ? 1 : 0;
+
+  db.prepare(
+    `INSERT OR REPLACE INTO memory_vec_meta
+       (id, active_dim, embedding_signature, last_reset_at, vec_loaded)
+     VALUES (1, ?, ?, ?, ?)`
+  ).run(activeDim, embeddingSignature, lastResetAt, vecLoaded);
+}
+
+// ──────────────── memories.needs_reindex ────────────────
+
+/**
+ * Mark a single memory as needing reindex (or clear the flag).
+ */
+export function markMemoryNeedsReindex(id: string, needs: boolean): void {
+  const db = getDbInstance();
+  db.prepare("UPDATE memories SET needs_reindex = ? WHERE id = ?").run(needs ? 1 : 0, id);
+}
+
+/**
+ * Mark ALL memories as needing reindex.
+ * Returns the number of rows affected.
+ */
+export function markAllMemoriesNeedReindex(): number {
+  const db = getDbInstance();
+  const result = db.prepare("UPDATE memories SET needs_reindex = 1").run();
+  return result.changes;
+}
+
+/**
+ * Get a batch of memories that need reindex, ordered by creation date ascending.
+ * Returns id, content, and key for each memory so the vector can be regenerated.
+ */
+export function getMemoryReindexQueue(
+  limit: number
+): Array<{ id: string; content: string; key: string }> {
+  const db = getDbInstance();
+  return db
+    .prepare(
+      `SELECT id, content, COALESCE(key, '') AS key
+       FROM memories
+       WHERE needs_reindex = 1
+       ORDER BY created_at ASC
+       LIMIT ?`
+    )
+    .all(limit) as Array<{ id: string; content: string; key: string }>;
+}
+
+/**
+ * Count how many memories currently have needs_reindex = 1.
+ */
+export function countMemoryReindexPending(): number {
+  const db = getDbInstance();
+  const row = db
+    .prepare("SELECT COUNT(*) AS cnt FROM memories WHERE needs_reindex = 1")
+    .get() as { cnt: number };
+  return row.cnt;
+}
diff --git a/src/lib/db/migrations/073_memory_vec.sql b/src/lib/db/migrations/073_memory_vec.sql
new file mode 100644
index 0000000000..ab7204f5d9
--- /dev/null
+++ b/src/lib/db/migrations/073_memory_vec.sql
@@ -0,0 +1,26 @@
+-- 073_memory_vec.sql
+-- Memory Engine Redesign (plan 21): metadata table for sqlite-vec.
+-- The actual virtual table `vec_memories(memory_id INTEGER, embedding float[N])`
+-- is created in runtime by src/lib/memory/vectorStore.ts because N depends on
+-- the active embedding model (which can change at any time via UI).
+
+CREATE TABLE IF NOT EXISTS memory_vec_meta (
+  id INTEGER PRIMARY KEY CHECK (id = 1),
+  active_dim INTEGER,
+  embedding_signature TEXT,
+  last_reset_at TEXT,
+  vec_loaded INTEGER NOT NULL DEFAULT 0
+);
+
+INSERT OR IGNORE INTO memory_vec_meta (id, active_dim, embedding_signature, last_reset_at, vec_loaded)
+VALUES (1, NULL, NULL, NULL, 0);
+
+-- Add needs_reindex column to memories (idempotent via separate ALTER guarded by PRAGMA).
+-- The PRAGMA-guard pattern is handled in the migration runner; here we just ensure the
+-- column shape. If the column already exists, the ALTER fails silently and the runner
+-- treats the migration as a no-op for that ALTER step.
+ALTER TABLE memories ADD COLUMN needs_reindex INTEGER NOT NULL DEFAULT 0;
+
+CREATE INDEX IF NOT EXISTS idx_memories_needs_reindex
+  ON memories(needs_reindex)
+  WHERE needs_reindex = 1;
diff --git a/src/lib/localDb.ts b/src/lib/localDb.ts
index 648c03f658..cba08c0836 100755
--- a/src/lib/localDb.ts
+++ b/src/lib/localDb.ts
@@ -508,3 +508,15 @@ export {
 } from "./db/freeProxies";
 
 export type { FreeProxyRecord, FreeProxyStats } from "./db/freeProxies";
+
+// Plan 21 — Memory Engine Redesign
+export {
+  getMemoryVecMeta,
+  setMemoryVecMeta,
+  markMemoryNeedsReindex,
+  markAllMemoriesNeedReindex,
+  getMemoryReindexQueue,
+  countMemoryReindexPending,
+} from "./db/memoryVec";
+
+export type { MemoryVecMeta } from "./db/memoryVec";
diff --git a/tests/unit/memory-needs-reindex.test.ts b/tests/unit/memory-needs-reindex.test.ts
new file mode 100644
index 0000000000..8818358a48
--- /dev/null
+++ b/tests/unit/memory-needs-reindex.test.ts
@@ -0,0 +1,251 @@
+/**
+ * tests/unit/memory-needs-reindex.test.ts
+ *
+ * Plan 21 — Memory Engine Redesign (F2)
+ * Tests for markMemoryNeedsReindex, markAllMemoriesNeedReindex,
+ * getMemoryReindexQueue, and countMemoryReindexPending.
+ */
+
+import test from "node:test";
+import assert from "node:assert/strict";
+import fs from "node:fs";
+import os from "node:os";
+import path from "node:path";
+
+const TEST_DATA_DIR = fs.mkdtempSync(path.join(os.tmpdir(), "omniroute-memory-reindex-"));
+process.env.DATA_DIR = TEST_DATA_DIR;
+process.env.DISABLE_SQLITE_AUTO_BACKUP = "true";
+
+const core = await import("../../src/lib/db/core.ts");
+const memoryVec = await import("../../src/lib/db/memoryVec.ts");
+
+// ──────────────── Helpers ────────────────
+
+function insertTestMemory(
+  db: ReturnType<typeof core.getDbInstance>,
+  id: string,
+  content: string,
+  key: string
+): void {
+  db.prepare(`
+    INSERT INTO memories (id, api_key_id, type, key, content, created_at, updated_at)
+    VALUES (?, ?, ?, ?, ?, datetime('now'), datetime('now'))
+  `).run(id, "test-api-key", "factual", key, content);
+}
+
+async function resetStorage() {
+  core.resetDbInstance();
+
+  for (let attempt = 0; attempt < 10; attempt++) {
+    try {
+      if (fs.existsSync(TEST_DATA_DIR)) {
+        fs.rmSync(TEST_DATA_DIR, { recursive: true, force: true });
+      }
+      break;
+    } catch (error: unknown) {
+      const code = (error as NodeJS.ErrnoException)?.code;
+      if ((code === "EBUSY" || code === "EPERM") && attempt < 9) {
+        await new Promise((resolve) => setTimeout(resolve, 50 * (attempt + 1)));
+      } else {
+        throw error;
+      }
+    }
+  }
+
+  fs.mkdirSync(TEST_DATA_DIR, { recursive: true });
+}
+
+test.beforeEach(async () => {
+  await resetStorage();
+});
+
+test.after(async () => {
+  core.resetDbInstance();
+  fs.rmSync(TEST_DATA_DIR, { recursive: true, force: true });
+});
+
+// ──────────────── markMemoryNeedsReindex ────────────────
+
+test("markMemoryNeedsReindex(id, true) marks only the targeted memory", () => {
+  const db = core.getDbInstance();
+
+  insertTestMemory(db, "id-1", "Paris is the capital of France", "capital-france");
+  insertTestMemory(db, "id-2", "Berlin is the capital of Germany", "capital-germany");
+  insertTestMemory(db, "id-3", "Tokyo is the capital of Japan", "capital-japan");
+
+  memoryVec.markMemoryNeedsReindex("id-1", true);
+
+  const queue = memoryVec.getMemoryReindexQueue(10);
+  assert.equal(queue.length, 1, "only 1 memory should be in the reindex queue");
+  assert.equal(queue[0].id, "id-1");
+  assert.equal(queue[0].content, "Paris is the capital of France");
+  assert.equal(queue[0].key, "capital-france");
+});
+
+test("markMemoryNeedsReindex(id, false) clears the flag for that memory", () => {
+  const db = core.getDbInstance();
+
+  insertTestMemory(db, "id-1", "Content 1", "key-1");
+  insertTestMemory(db, "id-2", "Content 2", "key-2");
+  insertTestMemory(db, "id-3", "Content 3", "key-3");
+
+  // Mark all 3 with needs_reindex
+  memoryVec.markMemoryNeedsReindex("id-1", true);
+  memoryVec.markMemoryNeedsReindex("id-2", true);
+  memoryVec.markMemoryNeedsReindex("id-3", true);
+
+  // Clear id-1
+  memoryVec.markMemoryNeedsReindex("id-1", false);
+
+  const queue = memoryVec.getMemoryReindexQueue(10);
+  const ids = queue.map((item) => item.id);
+
+  assert.equal(queue.length, 2, "queue should have 2 items after clearing id-1");
+  assert.ok(!ids.includes("id-1"), "id-1 should not be in the queue");
+  assert.ok(ids.includes("id-2"), "id-2 should be in the queue");
+  assert.ok(ids.includes("id-3"), "id-3 should be in the queue");
+});
+
+// ──────────────── markAllMemoriesNeedReindex ────────────────
+
+test("markAllMemoriesNeedReindex() returns the correct affected row count", () => {
+  const db = core.getDbInstance();
+
+  insertTestMemory(db, "id-1", "Content 1", "key-1");
+  insertTestMemory(db, "id-2", "Content 2", "key-2");
+  insertTestMemory(db, "id-3", "Content 3", "key-3");
+
+  const count = memoryVec.markAllMemoriesNeedReindex();
+  assert.equal(count, 3, "markAllMemoriesNeedReindex should return 3 (all rows affected)");
+});
+
+test("markAllMemoriesNeedReindex() marks every memory in the queue", () => {
+  const db = core.getDbInstance();
+
+  insertTestMemory(db, "id-1", "Content 1", "key-1");
+  insertTestMemory(db, "id-2", "Content 2", "key-2");
+  insertTestMemory(db, "id-3", "Content 3", "key-3");
+
+  memoryVec.markAllMemoriesNeedReindex();
+
+  const queue = memoryVec.getMemoryReindexQueue(10);
+  assert.equal(queue.length, 3, "all 3 memories should appear in the reindex queue");
+});
+
+test("markAllMemoriesNeedReindex() returns 0 when there are no memories", () => {
+  core.getDbInstance();
+
+  const count = memoryVec.markAllMemoriesNeedReindex();
+  assert.equal(count, 0, "should return 0 when there are no memories");
+});
+
+// ──────────────── countMemoryReindexPending ────────────────
+
+test("countMemoryReindexPending() returns 3 after markAll on 3 memories", () => {
+  const db = core.getDbInstance();
+
+  insertTestMemory(db, "id-1", "Content 1", "key-1");
+  insertTestMemory(db, "id-2", "Content 2", "key-2");
+  insertTestMemory(db, "id-3", "Content 3", "key-3");
+
+  memoryVec.markAllMemoriesNeedReindex();
+
+  const pending = memoryVec.countMemoryReindexPending();
+  assert.equal(pending, 3);
+});
+
+test("countMemoryReindexPending() returns 0 on fresh DB with no memories", () => {
+  core.getDbInstance();
+
+  const pending = memoryVec.countMemoryReindexPending();
+  assert.equal(pending, 0);
+});
+
+test("countMemoryReindexPending() decrements after clearing a flag", () => {
+  const db = core.getDbInstance();
+
+  insertTestMemory(db, "id-1", "Content 1", "key-1");
+  insertTestMemory(db, "id-2", "Content 2", "key-2");
+  insertTestMemory(db, "id-3", "Content 3", "key-3");
+
+  memoryVec.markAllMemoriesNeedReindex();
+  assert.equal(memoryVec.countMemoryReindexPending(), 3);
+
+  memoryVec.markMemoryNeedsReindex("id-1", false);
+  assert.equal(memoryVec.countMemoryReindexPending(), 2);
+
+  memoryVec.markMemoryNeedsReindex("id-2", false);
+  assert.equal(memoryVec.countMemoryReindexPending(), 1);
+});
+
+// ──────────────── getMemoryReindexQueue pagination ────────────────
+
+test("getMemoryReindexQueue respects the limit parameter", () => {
+  const db = core.getDbInstance();
+
+  for (let i = 1; i <= 5; i++) {
+    insertTestMemory(db, `id-${i}`, `Content ${i}`, `key-${i}`);
+  }
+
+  memoryVec.markAllMemoriesNeedReindex();
+
+  const queue = memoryVec.getMemoryReindexQueue(3);
+  assert.equal(queue.length, 3, "should return at most 3 items when limit=3");
+});
+
+test("getMemoryReindexQueue returns only memories with needs_reindex = 1", () => {
+  const db = core.getDbInstance();
+
+  insertTestMemory(db, "id-1", "Content 1", "key-1");
+  insertTestMemory(db, "id-2", "Content 2", "key-2");
+  insertTestMemory(db, "id-3", "Content 3", "key-3");
+
+  // Only mark id-2 and id-3
+  memoryVec.markMemoryNeedsReindex("id-2", true);
+  memoryVec.markMemoryNeedsReindex("id-3", true);
+
+  const queue = memoryVec.getMemoryReindexQueue(10);
+  const ids = queue.map((item) => item.id);
+
+  assert.equal(queue.length, 2);
+  assert.ok(!ids.includes("id-1"), "id-1 should NOT be in the queue");
+  assert.ok(ids.includes("id-2"), "id-2 should be in the queue");
+  assert.ok(ids.includes("id-3"), "id-3 should be in the queue");
+});
+
+test("getMemoryReindexQueue returns empty array when no memories need reindex", () => {
+  const db = core.getDbInstance();
+
+  insertTestMemory(db, "id-1", "Content 1", "key-1");
+
+  const queue = memoryVec.getMemoryReindexQueue(10);
+  assert.equal(queue.length, 0, "queue should be empty when needs_reindex = 0");
+});
+
+// ──────────────── Combined workflow ────────────────
+
+test("full workflow: markAll → queue=3 → clear id-1 → queue=2", () => {
+  const db = core.getDbInstance();
+
+  insertTestMemory(db, "id-1", "Content 1", "key-1");
+  insertTestMemory(db, "id-2", "Content 2", "key-2");
+  insertTestMemory(db, "id-3", "Content 3", "key-3");
+
+  const affected = memoryVec.markAllMemoriesNeedReindex();
+  assert.equal(affected, 3);
+
+  const queueBefore = memoryVec.getMemoryReindexQueue(10);
+  assert.equal(queueBefore.length, 3);
+  assert.equal(memoryVec.countMemoryReindexPending(), 3);
+
+  memoryVec.markMemoryNeedsReindex("id-1", false);
+
+  const queueAfter = memoryVec.getMemoryReindexQueue(10);
+  assert.equal(queueAfter.length, 2, "queue should have 2 items after clearing id-1");
+  assert.equal(memoryVec.countMemoryReindexPending(), 2);
+
+  const ids = queueAfter.map((item) => item.id);
+  assert.ok(!ids.includes("id-1"));
+  assert.ok(ids.includes("id-2"));
+  assert.ok(ids.includes("id-3"));
+});
diff --git a/tests/unit/memory-vec-meta.test.ts b/tests/unit/memory-vec-meta.test.ts
new file mode 100644
index 0000000000..9810f7fc19
--- /dev/null
+++ b/tests/unit/memory-vec-meta.test.ts
@@ -0,0 +1,159 @@
+/**
+ * tests/unit/memory-vec-meta.test.ts
+ *
+ * Plan 21 — Memory Engine Redesign (F2)
+ * Tests for getMemoryVecMeta / setMemoryVecMeta and migration idempotency.
+ */
+
+import test from "node:test";
+import assert from "node:assert/strict";
+import fs from "node:fs";
+import os from "node:os";
+import path from "node:path";
+
+const TEST_DATA_DIR = fs.mkdtempSync(path.join(os.tmpdir(), "omniroute-memory-vec-meta-"));
+process.env.DATA_DIR = TEST_DATA_DIR;
+process.env.DISABLE_SQLITE_AUTO_BACKUP = "true";
+
+const core = await import("../../src/lib/db/core.ts");
+const memoryVec = await import("../../src/lib/db/memoryVec.ts");
+
+async function resetStorage() {
+  core.resetDbInstance();
+
+  for (let attempt = 0; attempt < 10; attempt++) {
+    try {
+      if (fs.existsSync(TEST_DATA_DIR)) {
+        fs.rmSync(TEST_DATA_DIR, { recursive: true, force: true });
+      }
+      break;
+    } catch (error: unknown) {
+      const code = (error as NodeJS.ErrnoException)?.code;
+      if ((code === "EBUSY" || code === "EPERM") && attempt < 9) {
+        await new Promise((resolve) => setTimeout(resolve, 50 * (attempt + 1)));
+      } else {
+        throw error;
+      }
+    }
+  }
+
+  fs.mkdirSync(TEST_DATA_DIR, { recursive: true });
+}
+
+test.beforeEach(async () => {
+  await resetStorage();
+});
+
+test.after(async () => {
+  core.resetDbInstance();
+  fs.rmSync(TEST_DATA_DIR, { recursive: true, force: true });
+});
+
+// ──────────────── getMemoryVecMeta initial state ────────────────
+
+test("getMemoryVecMeta() returns expected defaults on a fresh DB", () => {
+  // getDbInstance() triggers migrations including 073_memory_vec.sql
+  const db = core.getDbInstance();
+  assert.ok(db, "DB instance should be created");
+
+  const meta = memoryVec.getMemoryVecMeta();
+
+  assert.equal(meta.activeDim, null, "activeDim should be null initially");
+  assert.equal(meta.embeddingSignature, null, "embeddingSignature should be null initially");
+  assert.equal(meta.lastResetAt, null, "lastResetAt should be null initially");
+  assert.equal(meta.vecLoaded, false, "vecLoaded should be false initially");
+});
+
+// ──────────────── setMemoryVecMeta + getMemoryVecMeta round-trip ────────────────
+
+test("setMemoryVecMeta persists activeDim and embeddingSignature", () => {
+  core.getDbInstance(); // ensure migrations run
+
+  memoryVec.setMemoryVecMeta({
+    activeDim: 1536,
+    embeddingSignature: "remote:openai/text-embedding-3-small:1536",
+  });
+
+  const meta = memoryVec.getMemoryVecMeta();
+
+  assert.equal(meta.activeDim, 1536);
+  assert.equal(meta.embeddingSignature, "remote:openai/text-embedding-3-small:1536");
+  assert.equal(meta.lastResetAt, null); // not set
+  assert.equal(meta.vecLoaded, false);  // not set
+});
+
+test("setMemoryVecMeta persists vecLoaded = true", () => {
+  core.getDbInstance();
+
+  memoryVec.setMemoryVecMeta({ vecLoaded: true });
+
+  const meta = memoryVec.getMemoryVecMeta();
+  assert.equal(meta.vecLoaded, true);
+});
+
+test("setMemoryVecMeta updates only the provided fields (partial update)", () => {
+  core.getDbInstance();
+
+  // First set all fields
+  memoryVec.setMemoryVecMeta({
+    activeDim: 768,
+    embeddingSignature: "static:potion-base-8M:768",
+    vecLoaded: true,
+  });
+
+  // Then update only activeDim
+  memoryVec.setMemoryVecMeta({ activeDim: 1536 });
+
+  const meta = memoryVec.getMemoryVecMeta();
+  assert.equal(meta.activeDim, 1536, "activeDim should be updated");
+  assert.equal(meta.embeddingSignature, "static:potion-base-8M:768", "embeddingSignature should be preserved");
+  assert.equal(meta.vecLoaded, true, "vecLoaded should be preserved");
+});
+
+test("setMemoryVecMeta sets lastResetAt correctly", () => {
+  core.getDbInstance();
+
+  const now = new Date().toISOString();
+  memoryVec.setMemoryVecMeta({ lastResetAt: now });
+
+  const meta = memoryVec.getMemoryVecMeta();
+  assert.equal(meta.lastResetAt, now);
+});
+
+// ──────────────── Migration idempotency ────────────────
+
+test("migration 073 does not duplicate memory_vec_meta sentinel row on second run", () => {
+  // The first getDbInstance() runs all migrations including 073
+  const db = core.getDbInstance();
+
+  // Run migration SQL a second time manually to simulate re-run
+  // The runner would normally catch "duplicate column name" and skip,
+  // but here we test CREATE TABLE IF NOT EXISTS + INSERT OR IGNORE
+  db.exec(`
+    CREATE TABLE IF NOT EXISTS memory_vec_meta (
+      id INTEGER PRIMARY KEY CHECK (id = 1),
+      active_dim INTEGER,
+      embedding_signature TEXT,
+      last_reset_at TEXT,
+      vec_loaded INTEGER NOT NULL DEFAULT 0
+    );
+    INSERT OR IGNORE INTO memory_vec_meta (id, active_dim, embedding_signature, last_reset_at, vec_loaded)
+    VALUES (1, NULL, NULL, NULL, 0);
+  `);
+
+  // Count should still be exactly 1
+  const row = db.prepare("SELECT COUNT(*) AS cnt FROM memory_vec_meta").get() as { cnt: number };
+  assert.equal(row.cnt, 1, "migration re-run must not duplicate the sentinel row");
+});
+
+test("migration 073 creates needs_reindex column in memories table", () => {
+  const db = core.getDbInstance();
+
+  const columns = db.prepare("PRAGMA table_info(memories)").all() as Array<{ name: string }>;
+  const colNames = columns.map((col) => col.name);
+
+  assert.ok(
+    colNames.includes("needs_reindex"),
+    "memories table must have needs_reindex column after migration 073"
+  );
+});