# `Milvex.Highlighter`

Builder functions for search result highlighting.

Two highlighting strategies are available:

- **Lexical** - matches based on exact token overlap (BM25 search)
- **Semantic** - matches based on meaning similarity using a deployed model

## Examples

    {:ok, hl} = Highlighter.lexical("content")
    {:ok, hl} = Highlighter.semantic(["what is AI?"], ["content", "title"],
      model_deployment_id: "my-model"
    )

# `t`

```elixir
@type t() :: %Milvex.Highlighter{params: map(), type: :lexical | :semantic}
```

# `lexical`

```elixir
@spec lexical(
  String.t(),
  keyword()
) :: {:ok, t()} | {:error, Milvex.Errors.Invalid.t()}
```

Creates a lexical highlighter for the given field.

Lexical highlighting matches based on exact token overlap between
the query and the document text. Works with BM25 search.

## Options

  - `:pre_tag` - Tag inserted before highlighted text (default: `"<b>"`)
  - `:post_tag` - Tag inserted after highlighted text (default: `"</b>"`)

## Examples

    {:ok, hl} = Highlighter.lexical("content")
    {:ok, hl} = Highlighter.lexical("content", pre_tag: "<em>", post_tag: "</em>")

# `semantic`

```elixir
@spec semantic([String.t()], [String.t()], keyword()) ::
  {:ok, t()} | {:error, Milvex.Errors.Invalid.t()}
```

Creates a semantic highlighter.

Semantic highlighting matches based on meaning similarity using a
deployed model. Requires explicit queries and input fields.

## Parameters

  - `queries` - List of search query strings to match against documents
  - `input_fields` - List of field names to highlight

## Options

  - `:pre_tags` - List of tags inserted before highlighted text
  - `:post_tags` - List of tags inserted after highlighted text
  - `:threshold` - Minimum confidence score (0.0 to 1.0) to trigger highlighting
  - `:highlight_only` - If true, returns only highlighted snippets instead of full text
  - `:model_deployment_id` - ID of the deployed model for semantic inference
  - `:max_client_batch_size` - Limits items processed in a single batch

## Examples

    {:ok, hl} = Highlighter.semantic(["what is AI?"], ["content"])
    {:ok, hl} = Highlighter.semantic(["search query"], ["title", "body"],
      threshold: 0.5,
      model_deployment_id: "my-model"
    )

---

*Consult [api-reference.md](api-reference.md) for complete listing*