foresight_memory

# Getting started

## Install

```elixir
# mix.exs
def deps do
  [{:foresight, "~> 0.1", hex: :foresight_memory}]
end
```

That is the whole dependency line. The `hex:` option is there because the package is
published as **`foresight_memory`** — the plain name belongs to an unrelated library on
hex. Nothing else is affected: the application is `:foresight`, the modules are
`Foresight.*`, and you write `alias Foresight` as you would expect.

Foresight compiles and boots with no configuration at all — you can verify that
before writing any config:

```elixir
{:ok, _pid} = Foresight.Supervisor.start_link(name: :foresight)
```

This is worth stating explicitly because for a long time it was not true. The
HTTP modules referenced `plug` while declaring it optional, so a bare install
failed with a `CompileError`, and the default reranker demanded the whole
Nx/Bumblebee stack, so even after compiling it would not start. Both are fixed,
and there is a test in the default suite that fails if either regresses.

With no configuration you get an in-memory-free, LLM-free skeleton: it starts,
but it cannot embed, rerank, or store anything. Useful for confirming the wiring
and not much else.

## A working configuration

Memory needs somewhere to live. Foresight uses PostgreSQL with
[pgvector](https://github.com/pgvector/pgvector).

```elixir
# config/config.exs
config :foresight,
  repo: [enabled: true],
  engine: [
    embedder: Foresight.Embedders.Bumblebee,
    reranker: Foresight.Rerankers.Passthrough,
    llm: Foresight.LLMs.LlmCore
  ]

config :foresight, Foresight.Repo,
  url: "postgresql://postgres:postgres@localhost:5432/my_app_memory"
```

```elixir
# mix.exs — capabilities you enable, you must also depend on
{:bumblebee, "~> 0.7"}, {:nx, "~> 0.12"}, {:exla, "~> 0.12"},  # local embeddings
{:llm_core, "~> 0.5"}                                          # LLM access
```

Then run the migrations:

```bash
mix ecto.create
mix ecto.migrate
```

### The one trap

**`embedder` and `reranker` live under `engine:`.** Set them at the top level and
nothing happens — silently. No error, no warning; your configuration is simply
ignored and the defaults stand.

```elixir
config :foresight, embedder: MyEmbedder          # ✗ silently ignored
config :foresight, engine: [embedder: MyEmbedder] # ✓
```

The failure surfaces much later and points somewhere else entirely — usually as a
preflight complaint about `:nx`, because the ignored setting left the default in
place. If a config change appears to have had no effect, check the nesting first.

### The preflight is on your side

Enable a capability without its dependency and Foresight refuses to start, by
name:

```
** (RuntimeError) Foresight capability preflight failed:
   optional dependency :nx is not available.
   Add/fetch the dependency before enabling the related capability.
```

This is deliberate. The alternative is booting successfully and failing on the
first request that happens to need embeddings — at which point the error appears
somewhere far from its cause.

## Your first memories

```elixir
alias Foresight.Context

ctx = %Context{tenant_id: "default", mode: :mode_a, bank: "notes"}

{:ok, _} = Foresight.put_bank(ctx, "notes", %{"name" => "Notes"})

{:ok, _} =
  Foresight.retain(ctx, %{
    "items" => [
      %{"content" => "Deployed v2.3 on Tuesday. The migration took 40 minutes.",
        "context" => "ops log"}
    ]
  })

{:ok, result} = Foresight.recall(ctx, %{"query" => "how long did the migration take?"})
```

A **bank** is an isolated namespace of memory — one per agent, per user, per
project, whatever your unit of "a memory" is. Banks do not share retrieval;
searching one never returns another's contents.

The **context** carries tenant, isolation mode and bank on every call. There is
no ambient state and no "current bank": if a call touches memory, it says whose.
This is tedious for exactly as long as it takes to appreciate that no request can
accidentally read another tenant's data.

## Retain is not an insert

`retain` extracts. One paragraph typically becomes several dated facts, each
independently retrievable, with entities pulled out and linked.

That means it costs an LLM call and takes real time — and it is where quality is
won or lost. When fact extraction was subtly wrong in this library (it dropped
the `When:` clause from every stored fact), end-to-end answer accuracy sat at
**0.467**. Fixing extraction alone took it to **0.711**. Nothing about retrieval
or reasoning changed.

If you are debugging poor answers, look at what `retain` actually stored before
you look at anything else. `Foresight.list_memories/3` shows you.

## Then reflect

```elixir
{:ok, answer} = Foresight.reflect(ctx, %{"query" => "what happened with v2.3?"})
```

`reflect` needs an LLM configured. See **[Reflect](reflect.md)** for the loop it
runs and how to confirm it did.