fleet-memory/hindsight-docs/docs/developer/api/recall.mdx

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# Recall Memories

Retrieve memories using multi-strategy recall.

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:::info How Recall Works
Learn about the four retrieval strategies (semantic, keyword, graph, temporal) and RRF fusion in the [Recall Architecture](/developer/retrieval) guide.
:::

:::tip Prerequisites
Make sure you've completed the [Quick Start](./quickstart) to install the client and start the server.
:::

## Basic Recall

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## Recall Parameters

| Parameter | Type | Default | Description |
|-----------|------|---------|-------------|
| `query` | string | required | Natural language query |
| `types` | list | all | Filter: `world`, `experience`, `observation` |
| `budget` | string | "mid" | Budget level: `low`, `mid`, `high` |
| `max_tokens` | int | 4096 | Token budget for results |
| `trace` | bool | false | Enable trace output for debugging |
| `include_chunks` | bool | false | Include raw text chunks that generated the memories |
| `max_chunk_tokens` | int | 500 | Token budget for chunks |
| `tags` | list | None | Filter memories by tags (see [Tag Filtering](#filter-by-tags)) |
| `tags_match` | string | "any" | How to match tags: `any`, `all`, `any_strict`, `all_strict` |

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## Filter by Fact Type

Recall specific memory types:

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:::tip About Observations
Observations are consolidated knowledge synthesized from multiple facts. They capture patterns, preferences, and learnings that the memory bank has built up over time. Observations are automatically created in the background after retain operations.
:::

## Token Budget Management

Hindsight is built for AI agents, not humans. Traditional retrieval systems return "top-k" results, but agents don't think in terms of result counts—they think in tokens. An agent's context window is measured in tokens, and that's exactly how Hindsight measures results.

The `max_tokens` parameter lets you control how much of your agent's context budget to spend on memories:

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This design means you never have to guess whether 10 results or 50 results will fit your context. Just specify the token budget and Hindsight returns as many relevant memories as will fit.

## Budget Levels

The `budget` parameter controls graph traversal depth:

- **"low"**: Fast, shallow retrieval — good for simple lookups
- **"mid"**: Balanced — default for most queries
- **"high"**: Deep exploration — finds indirect connections

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## Filter by Tags

Tags enable **visibility scoping**—filter memories based on tags assigned during [retain](./retain#tagging-memories). This is essential for multi-user agents where each user should only see their own memories.

### Basic Tag Filtering

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### Tag Match Modes

The `tags_match` parameter controls how tags are matched:

| Mode | Behavior | Untagged Memories |
|------|----------|-------------------|
| `any` | OR: memory has ANY of the specified tags | **Included** |
| `all` | AND: memory has ALL of the specified tags | **Included** |
| `any_strict` | OR: memory has ANY of the specified tags | **Excluded** |
| `all_strict` | AND: memory has ALL of the specified tags | **Excluded** |

**Strict modes** are useful when you want to ensure only tagged memories are returned:

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**AND matching** requires all specified tags to be present:

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### Use Cases

| Scenario | Tags | Mode | Result |
|----------|------|------|--------|
| User A's memories only | `["user:alice"]` | `any_strict` | Only memories tagged `user:alice` |
| Support + feedback | `["support", "feedback"]` | `any` | Memories with either tag + untagged |
| Multi-user room | `["user:alice", "room:general"]` | `all_strict` | Only memories with both tags |
| Global + user-specific | `["user:alice"]` | `any` | Alice's memories + shared (untagged) |