TanStack · AlemTuzlak · May 10, 2026 · May 10, 2026 · May 10, 2026 · May 10, 2026
diff --git a/.changeset/memory-middleware.md b/.changeset/memory-middleware.md
@@ -0,0 +1,25 @@
+---
+'@tanstack/ai': minor
+'@tanstack/ai-event-client': minor
+'@tanstack/ai-memory': minor
+---
+
+**Add server-side memory support via `memoryMiddleware`.**
+
+A new `memoryMiddleware` from `@tanstack/ai/memory` retrieves relevant memories at chat init and persists user/assistant turns + tool results at finish. The middleware injects a rendered system prompt before the model call and runs persistence via `ctx.defer` so streaming is never blocked.
+
+`@tanstack/ai`:
+
+- New subpath `@tanstack/ai/memory` exporting `memoryMiddleware`, the `MemoryAdapter` / `MemoryRecord` / `MemoryScope` types, the `MemoryOp` union, helpers (`scopeMatches`, `cosine`, `lexicalOverlap`, `recencyScore`, `defaultRenderMemory`, `defaultScoreHit`, `isExpired`).
+- Middleware extension hooks: `shouldRetrieve`, `rerank`, `shouldRemember`, `extractMemories`, `onToolResult`, `afterPersist`, plus app-level `events.*` callbacks and a `strict` mode.
+
+`@tanstack/ai-event-client`:
+
+- Five new events on `AIDevtoolsEventMap`: `memory:retrieve:started`, `memory:retrieve:completed`, `memory:persist:started`, `memory:persist:completed`, `memory:error`.
+
+`@tanstack/ai-memory` (new package):
+
+- `inMemoryMemoryAdapter()` — zero-dep adapter for dev/tests.
+- `redisMemoryAdapter({ redis, prefix? })` — production adapter for plain Redis. `ioredis` and `redis` (node-redis v4+) are both supported as optional peer dependencies.
+- `nodeRedisAsRedisLike(client)` — helper for users wiring `redis` (node-redis v4+) without `legacyMode`; translates the camelCase API into the lowercase `RedisLike` shape the adapter expects. `ioredis` clients wire in directly without a wrapper.
+- Both adapters pass a shared contract suite covering scope isolation, expiry, cursor pagination, kinds filtering, lexical-only ranking, semantic ranking with embeddings, and serialization round-trip (Redis).
diff --git a/docs/config.json b/docs/config.json
@@ -164,6 +164,23 @@
         }
       ]
     },
+    {
+      "label": "Memory",
+      "children": [
+        {
+          "label": "Overview",
+          "to": "memory/overview"
+        },
+        {
+          "label": "Quickstart",
+          "to": "memory/quickstart"
+        },
+        {
+          "label": "Custom Adapter",
+          "to": "memory/custom-adapter"
+        }
+      ]
+    },
     {
       "label": "Advanced",
       "children": [

diff --git a/docs/memory/custom-adapter.md b/docs/memory/custom-adapter.md
@@ -0,0 +1,315 @@
+---
+title: Custom Adapter
+id: memory-custom-adapter
+order: 3
+description: "Write a MemoryAdapter for a backend that isn't shipped — pgvector, MongoDB, DynamoDB, Pinecone, Supabase. Walks through the eight contract members, the three isolation invariants, the shared contract test suite, and publishing as a package."
+keywords:
+  - tanstack ai
+  - memory
+  - custom adapter
+  - MemoryAdapter
+  - pgvector
+  - mongodb
+  - dynamodb
+  - pinecone
+  - supabase
+  - contract suite
+---
+
+You have a backend in mind — pgvector, MongoDB, DynamoDB, Pinecone, Supabase, a hand-rolled SQL table — and the built-in `inMemoryMemoryAdapter` and `redisMemoryAdapter` don't fit. By the end of this guide, you'll have a working adapter that passes the shared contract suite, plugs into `memoryMiddleware`, and is ready to publish if you want.
+
+> **Already comfortable with the contract?** Jump to [Step 4 — Run the contract suite](#step-4--run-the-contract-suite). **First time looking at memory?** Start with the [Overview](./overview) for what `MemoryAdapter` is and what it does.
+
+## When to write a custom adapter
+
+| Situation | Use this |
+|-----------|----------|
+| You already use Postgres + pgvector / Supabase / Neon for app data | Custom adapter (one fewer system to operate) |
+| You need ANN search through a hosted vector DB (Pinecone, Weaviate, Qdrant) | Custom adapter |
+| You need DynamoDB / Cosmos / Spanner for compliance or existing infra | Custom adapter |
+| You want to layer caching, encryption, or tenant routing in front of an existing adapter | Custom adapter that wraps `inMemoryMemoryAdapter` or `redisMemoryAdapter` |
+| Local dev or single-process demo | `inMemoryMemoryAdapter` from `@tanstack/ai-memory` |
+| Production with Redis already in your stack | `redisMemoryAdapter` from `@tanstack/ai-memory` |
+
+If a built-in fits, use it. The contract is documented precisely so a custom adapter is always an option — not a requirement.
+
+## The contract at a glance
+
+A `MemoryAdapter` has one identifier and seven methods. The [Overview](./overview#adapter-contract) page covers each method's semantics in detail; this guide focuses on the implementation journey.
+
+```ts
+import type {
+  MemoryAdapter,
+  MemoryRecord,
+  MemoryRecordPatch,
+  MemoryScope,
+  MemoryQuery,
+  MemorySearchResult,
+  MemoryListOptions,
+  MemoryListResult,
+} from '@tanstack/ai/memory'
+
+interface MemoryAdapter {
+  name: string
+  add(records: MemoryRecord | MemoryRecord[]): Promise<void>
+  get(id: string, scope: MemoryScope): Promise<MemoryRecord | undefined>
+  update(id: string, scope: MemoryScope, patch: MemoryRecordPatch): Promise<MemoryRecord | undefined>
+  search(query: MemoryQuery): Promise<MemorySearchResult>
+  list(scope: MemoryScope, options?: MemoryListOptions): Promise<MemoryListResult>
+  delete(ids: string[], scope: MemoryScope): Promise<void>
+  clear(scope: MemoryScope): Promise<void>
+}
+```
+
+Three invariants every adapter MUST uphold — these are non-negotiable:
+
+1. **Scope isolation.** Reads and writes never cross scopes. A query for `{tenantId: 't1'}` MUST NOT return records belonging to `{tenantId: 't2'}`.
+2. **Expiry filtering.** Records whose `expiresAt` is in the past MUST be excluded from `get`, `search`, and `list`. Adapters SHOULD opportunistically sweep them on `add`.
+3. **Id uniqueness across all scopes.** Two records with the same `id` MUST NOT coexist, even if their scopes differ.
+
+The shared contract suite in `@tanstack/ai-memory/tests/contract.ts` verifies all three across every method. If your adapter passes it, the middleware works.
+
+## Step 1 — Scaffold the adapter shape
+
+Pick a backend and stub the eight members. Here's a pgvector skeleton you can copy as a starting point:
+
+```ts
+import type {
+  MemoryAdapter,
+  MemoryListOptions,
+  MemoryListResult,
+  MemoryQuery,
+  MemoryRecord,
+  MemoryRecordPatch,
+  MemoryScope,
+  MemorySearchResult,
+} from '@tanstack/ai/memory'
+import type { Pool } from 'pg'
+
+export interface PgvectorMemoryAdapterOptions {
+  pool: Pool
+  /** Table name. Defaults to "tanstack_ai_memory". */
+  table?: string
+}
+
+export function pgvectorMemoryAdapter(
+  options: PgvectorMemoryAdapterOptions,
+): MemoryAdapter {
+  const table = options.table ?? 'tanstack_ai_memory'
+  const pool = options.pool
+
+  return {
+    name: 'pgvector',
+    async add(records) { /* … */ },
+    async get(id, scope) { /* … */ },
+    async update(id, scope, patch) { /* … */ },
+    async search(query) { /* … */ },
+    async list(scope, options) { /* … */ },
+    async delete(ids, scope) { /* … */ },
+    async clear(scope) { /* … */ },
+  }
+}
+```
+
+Pick a `name` your operators will see in logs and devtools — usually the backend's name.
+
+## Step 2 — Reuse the shared helpers
+
+`@tanstack/ai/memory` exports helpers that handle the parts of the contract that don't depend on your storage choice. Use them instead of reimplementing:
+
+```ts
+import {
+  scopeMatches,
+  isExpired,
+  defaultScoreHit,
+  cosine,
+  lexicalOverlap,
+  recencyScore,
+} from '@tanstack/ai/memory'
+```
+
+- `scopeMatches(recordScope, queryScope)` — the canonical "does this record match this query scope?" check. Treats empty-string values and empty objects as no-match. Use everywhere you'd filter by scope.
+- `isExpired(record, now?)` — returns `true` for records past their `expiresAt`. Inject `now` for deterministic tests.
+- `defaultScoreHit({ record, query, now? })` — weighted score: semantic 0.55, lexical 0.20, recency 0.15, importance 0.10. Use as your default ranker, or roll your own and reuse `cosine` / `lexicalOverlap` / `recencyScore` à la carte.
+
+If your backend has native vector or full-text search (pgvector's `<->`, Postgres `ts_rank`, Pinecone's score), prefer it — the helpers are for adapters with no native ranking.
+
+## Step 3 — Implement each method
+
+Implementation specifics are backend-dependent, but the shape is the same everywhere. A pgvector example for `add` and `search` makes the pattern concrete:
+
+```ts
+async add(input) {
+  const batch = Array.isArray(input) ? input : [input]
+  const now = Date.now()
+
+  for (const r of batch) {
+    await pool.query(
+      `INSERT INTO ${table} (id, tenant_id, user_id, session_id, thread_id, namespace,
+                            text, kind, role, created_at, updated_at, expires_at,
+                            importance, embedding, metadata)
+       VALUES ($1, $2, $3, $4, $5, $6, $7, $8, $9, $10, $11, $12, $13, $14, $15)
+       ON CONFLICT (id) DO UPDATE SET
+         tenant_id = EXCLUDED.tenant_id,
+         user_id = EXCLUDED.user_id,
+         session_id = EXCLUDED.session_id,
+         thread_id = EXCLUDED.thread_id,
+         namespace = EXCLUDED.namespace,
+         text = EXCLUDED.text,
+         kind = EXCLUDED.kind,
+         role = EXCLUDED.role,
+         updated_at = EXCLUDED.updated_at,
+         expires_at = EXCLUDED.expires_at,
+         importance = EXCLUDED.importance,
+         embedding = EXCLUDED.embedding,
+         metadata = EXCLUDED.metadata`,
+      [
+        r.id, r.scope.tenantId ?? null, r.scope.userId ?? null,
+        r.scope.sessionId ?? null, r.scope.threadId ?? null, r.scope.namespace ?? null,
+        r.text, r.kind, r.role ?? null, r.createdAt ?? now, now,
+        r.expiresAt ?? null, r.importance ?? null,
+        r.embedding ? JSON.stringify(r.embedding) : null,
+        r.metadata ? JSON.stringify(r.metadata) : null,
+      ],
+    )
+  }
+},
+
+async search(query: MemoryQuery): Promise<MemorySearchResult> {
+  const topK = query.topK ?? 6
+  const minScore = query.minScore ?? 0
+  const offset = query.cursor ? Number.parseInt(query.cursor, 10) || 0 : 0
+
+  const { rows } = await pool.query(
+    `SELECT *,
+            CASE WHEN $1::vector IS NOT NULL AND embedding IS NOT NULL
+                 THEN 1 - (embedding <=> $1::vector)
+                 ELSE 0
+            END AS score
+       FROM ${table}
+      WHERE ($2::text IS NULL OR tenant_id = $2)
+        AND ($3::text IS NULL OR user_id = $3)
+        AND ($4::text IS NULL OR session_id = $4)
+        AND ($5::text IS NULL OR thread_id = $5)
+        AND ($6::text IS NULL OR namespace = $6)
+        AND (expires_at IS NULL OR expires_at > $7)
+        AND ($8::text[] IS NULL OR kind = ANY($8))
+      ORDER BY score DESC
+      OFFSET $9 LIMIT $10`,
+    [
+      query.embedding ? JSON.stringify(query.embedding) : null,
+      query.scope.tenantId ?? null, query.scope.userId ?? null,
+      query.scope.sessionId ?? null, query.scope.threadId ?? null,
+      query.scope.namespace ?? null,
+      Date.now(),
+      query.kinds ?? null,
+      offset, topK + 1,
+    ],
+  )
+
+  const hits = rows.slice(0, topK).map((row) => ({
+    record: rowToRecord(row),
+    score: Number(row.score),
+  })).filter((h) => h.score >= minScore)
+
+  return {
+    hits,
+    nextCursor: rows.length > topK ? String(offset + topK) : undefined,
+  }
+}
+```
+
+The shape generalizes: every method takes a `scope`, does its backend-specific work, and respects the three invariants. For backends without native search, fall back to "load scope-matched records, score via `defaultScoreHit`, sort, slice" — that's exactly what `inMemoryMemoryAdapter` does.
+
+## Step 4 — Run the contract suite
+
+The shared test suite in `@tanstack/ai-memory/tests/contract.ts` is the canonical verification for any adapter. Import `runMemoryAdapterContract` and point it at a factory that returns a fresh adapter:
+
+```ts
+// tests/pgvector.test.ts
+import { Pool } from 'pg'
+import { runMemoryAdapterContract } from '@tanstack/ai-memory/tests/contract'
+import { pgvectorMemoryAdapter } from '../src/pgvector'
+
+runMemoryAdapterContract('pgvectorMemoryAdapter', async () => {
+  const pool = new Pool({ connectionString: process.env.TEST_DATABASE_URL })
+  // Truncate the table between tests so each test gets a clean adapter.
+  await pool.query('TRUNCATE tanstack_ai_memory')
+  return pgvectorMemoryAdapter({ pool })
+})
+```
+
+The suite covers `add` (single, batch, upsert), `get`, `update`, `search` (topK, minScore, kinds filter, cursor pagination, lexical-vs-semantic ranking), `list`, `delete`, `clear`, scope isolation across every method, expiry filtering, partial-scope cascades, glob metacharacter safety, and colon and underscore safety. If your adapter passes, every adapter-level contract guarantee is met.
+
+The contract module isn't re-exported from `@tanstack/ai-memory`'s public entry yet — import directly from `@tanstack/ai-memory/tests/contract` until that lands.
+
+## Step 5 — Wire it into `memoryMiddleware`
+
+Once the contract suite is green, the adapter is interchangeable with the built-ins:
+
+```ts
+import { chat } from '@tanstack/ai'
+import { openaiText } from '@tanstack/ai-openai'
+import { memoryMiddleware } from '@tanstack/ai/memory'
+import { Pool } from 'pg'
+import { pgvectorMemoryAdapter } from './pgvector-adapter'
+
+const pool = new Pool({ connectionString: process.env.DATABASE_URL })
+const memory = pgvectorMemoryAdapter({ pool })
+
+const stream = chat({
+  adapter: openaiText('gpt-4o'),
+  messages,
+  middleware: [memoryMiddleware({ adapter: memory, scope })],
+})
+```
+
+Everything the middleware does — retrieval, deferred persistence, `extractMemories`, `onToolResult`, `afterPersist`, devtools events — works exactly the same. The middleware never inspects the adapter's internals; the contract is the entire interface.
+
+## Step 6 — Publish (optional)
+
+If you want others to use your adapter, ship it as its own package. The conventions:
+
+- Name it `@your-org/ai-memory-<backend>` (e.g. `@acme/ai-memory-pgvector`).
+- List `@tanstack/ai` as a peer dependency with a workspace-friendly range — `">=0.16.0 <1"` is typical.
+- List your backend client (`pg`, `mongodb`, `@pinecone-database/pinecone`, …) as a peer dependency, marked optional via `peerDependenciesMeta` if your adapter accepts any compatible shape (BYO-client pattern, like `redisMemoryAdapter`).
+- Include the contract suite as a `devDependency` so consumers can run the same tests against forks.
+- Re-export the relevant types from `@tanstack/ai/memory` for ergonomics.
+
+A minimal `package.json` for a published adapter:
+
+```json
+{
+  "name": "@acme/ai-memory-pgvector",
+  "version": "0.1.0",
+  "type": "module",
+  "exports": { ".": { "types": "./dist/index.d.ts", "import": "./dist/index.js" } },
+  "peerDependencies": {
+    "@tanstack/ai": ">=0.16.0 <1",
+    "pg": ">=8"
+  },
+  "peerDependenciesMeta": { "pg": { "optional": false } },
+  "devDependencies": {
+    "@tanstack/ai": "^0.16.0",
+    "@tanstack/ai-memory": "^0.1.0",
+    "pg": "^8",
+    "vitest": "^1"
+  }
+}
+```
+
+## Pitfalls
+
+A few things that catch first-time adapter authors:
+
+- **Don't trust the caller's `record.scope`.** The middleware overrides it before calling `add`, so adapter implementations should not silently rewrite scope based on caller intent. If your storage encodes scope into keys, take it from the record you were handed — and treat empty values defensively.
+- **Escape your delimiters.** If your storage serializes scope into a composite key, escape any character your delimiter uses (`:`, `_`, `/`, …) when it appears inside a user-supplied scope value. Otherwise a tenant whose id legitimately contains the delimiter will collide with sub-scope buckets. The Redis adapter handles this with an `escapeScopeValue` helper.
+- **Make `clear` cascade correctly.** `clear({tenantId: 't1'})` MUST wipe every record whose scope is `t1`-prefixed (e.g. `{tenantId: 't1', userId: 'u1'}`), not only records whose scope is exactly `{tenantId: 't1'}`. This is the partial-scope contract — the in-memory adapter gets it for free via `scopeMatches`; the Redis adapter implements it via SCAN over a glob pattern.
+- **Multi-step writes are not atomic by default.** If your backend supports transactions (Postgres, MongoDB sessions, DynamoDB transact-write), use them for `add` on scope changes and for `clear`. Document the consistency guarantee you provide.
+- **Refuse `clear({})`.** Empty scope is documented as misuse. `scopeMatches` returns `false` for it, so adapters using the helper get the guard for free. Adapters that bypass `scopeMatches` (Redis with its SCAN path) need an explicit `hasAnyScopeKey` check.
+
+## Where to go next
+
+- [Overview](./overview) — adapter contract, hooks reference, devtools events, failure modes
+- [Quickstart](./quickstart) — wire `memoryMiddleware` into a real `chat()` call
+- [Middleware](../advanced/middleware) — the underlying `chat()` middleware lifecycle, useful when your adapter needs to coordinate with other middlewares