# ExAthena

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Provider-agnostic agent loop for Elixir. Drop-in replacement for the Claude
Code SDK that runs on **Ollama**, **OpenAI-compatible endpoints**
(OpenAI, OpenRouter, LM Studio, vLLM, Groq, Together, llama.cpp server…),
**Google Gemini**, or **Anthropic Claude** itself — with the same tools,
hooks, permissions, and streaming semantics across every provider.

> **Status (v0.4):** the operational-harness release. Builds on v0.3's
> loop kernel with file-based memory (`AGENTS.md`/`CLAUDE.md`),
> Claude Code-style skills (`SKILL.md` with progressive disclosure), a
> five-stage compaction pipeline with reactive recovery on
> context-window errors, 14 hook events with `{:inject, msg}` /
> `{:transform, prompt}` returns, five permission modes (`:plan` /
> `:default` / `:accept_edits` / `:trusted` / `:bypass_permissions`),
> structured tool results with rich UI payloads, custom agent
> definitions with optional git-worktree isolation, sidechain
> transcripts, and append-only session storage with file-checkpointing
> + `/rewind`. Backed by 248 tests.
>
> See the [v0.4.0 changelog](CHANGELOG.md#v040--operational-harness-memory-skills-hooks-modes-agents-storage)
> for the full list and migration notes (one breaking change: 6 builtin
> tools now return `{:ok, text, ui}` 3-tuples).

## Why

If you're using `claude_code` today and want to switch to a local Ollama
model — or route per-task to OpenAI-compatible endpoints, or try Groq
behind the same Elixir code — you don't want to rewrite every orchestrator.
ExAthena is that abstraction layer. Pick a provider, run the same call,
get back the same shape.

## Install

The one-liner (Igniter auto-installs + writes sensible config):

```bash
mix igniter.install ex_athena
```

Or manually — add to `mix.exs`:

```elixir
def deps do
  [
    {:ex_athena, "~> 0.4"},
    # optional — only needed for the Claude provider:
    {:claude_code, "~> 0.36"}
  ]
end
```

…then run `mix ex_athena.install` once to wire up defaults, or configure
manually (see [Configuration](#configuration)).

## Quick start

```elixir
# config/config.exs
config :ex_athena, default_provider: :ollama
config :ex_athena, :ollama, base_url: "http://localhost:11434", model: "llama3.1"

# anywhere
{:ok, response} = ExAthena.query("Tell me a joke")
IO.puts(response.text)

# streaming
ExAthena.stream("Explain quantum computing", fn event ->
  case event.type do
    :text_delta -> IO.write(event.data)
    :stop -> IO.puts("\n[done]")
    _ -> :ok
  end
end)
```

Swap the provider by changing one option:

```elixir
ExAthena.query("hi", provider: :openai_compatible, model: "gpt-4o-mini")
ExAthena.query("hi", provider: :claude, model: "claude-opus-4-5")
ExAthena.query("hi", provider: :ollama, model: "qwen2.5-coder")
ExAthena.query("hi", provider: :gemini, model: "gemini-2.5-flash")
```

## Providers

| Provider | Module | Notes |
|---|---|---|
| `:ollama` | `ExAthena.Providers.ReqLLM` | Local Ollama, `/api/chat`. Native tool-calls on modern models. |
| `:openai_compatible` | `ExAthena.Providers.ReqLLM` | `/v1/chat/completions` — covers OpenAI, OpenRouter, LM Studio, vLLM, Groq, Together, llama.cpp server mode, etc. |
| `:openai` | `ExAthena.Providers.ReqLLM` | Alias for `:openai_compatible`. |
| `:llamacpp` | `ExAthena.Providers.ReqLLM` | Alias for local llama.cpp server. |
| `:claude` | `ExAthena.Providers.ReqLLM` | Anthropic Claude via req_llm. |
| `:gemini` | `ExAthena.Providers.ReqLLM` | Google Gemini via AI Studio (routed through `req_llm`'s Google adapter). Native tool calls + streaming. See [setup guide](guides/gemini.md). |
| `:mock` | `ExAthena.Providers.Mock` | In-memory test double. |

Pass a custom module that implements `ExAthena.Provider` directly if you
have an endpoint that doesn't fit the above.

## Configuration

```elixir
config :ex_athena,
  default_provider: :ollama

config :ex_athena, :ollama,
  base_url: "http://localhost:11434",
  model: "llama3.1"

config :ex_athena, :openai_compatible,
  base_url: "https://api.openai.com/v1",
  api_key: System.get_env("OPENAI_API_KEY"),
  model: "gpt-4o-mini"

config :ex_athena, :claude,
  api_key: System.get_env("ANTHROPIC_API_KEY"),
  model: "claude-opus-4-5"
```

Resolution is **tiered** — per-call opts always beat app env:

```elixir
ExAthena.query("…",
  provider: :openai_compatible,          # overrides default_provider
  base_url: "https://openrouter.ai/api/v1",  # overrides :openai_compatible, base_url
  api_key: System.get_env("OPENROUTER_API_KEY"),
  model: "anthropic/claude-opus-4.1")
```

## Tool calls

`ExAthena.ToolCalls` handles both protocols and auto-falls-back between them:

- **Native** — OpenAI `tool_calls` arrays and Anthropic `tool_use` blocks.
  Parsed into canonical `ExAthena.Messages.ToolCall` structs.
- **TextTagged** — `~~~tool_call {json}` fenced blocks embedded in assistant
  prose, for models without native support.

The agent loop (Phase 2) will pick the protocol based on the provider's
declared capabilities, and fall back when the model gets it wrong.

## What's in v0.4

The "1.6% reasoning, 98.4% harness" upgrade — built around the
[Claude Code paper](https://arxiv.org/abs/2604.14228)'s observation
that production agent value comes from the operational scaffolding,
not the loop itself.

**File-based context.** Drop an `AGENTS.md` (or `CLAUDE.md`) at the
project root and ex_athena prepends it as user-context on every turn.
Drop a `SKILL.md` with YAML frontmatter under `.exathena/skills/<name>/`
and its description joins the system-prompt catalog at ~50 tokens; the
body loads only when the model writes `[skill: <name>]`. See the
[memory + skills guide](guides/memory_and_skills.md).

**Five-stage compaction.** The default
[Compactor.Pipeline](guides/compaction_pipeline.md) runs cheapest-first:
budget reduction (truncate huge tool results) → snip (drop stale
ones) → microcompact (collapse runs of identical calls) → context
collapse (read-time-only projection) → LLM summary. When a provider
returns "context too long" the pipeline forces every stage and
retries.

**14-event hook surface.** Every transition in the loop is
observable + interceptable: `SessionStart/End`, `UserPromptSubmit`,
`ChatParams`, `Stop`, `StopFailure`, all the `*ToolUse*` variants,
`PermissionRequest/Denied`, `Subagent*`, three compaction events,
`Notification`. Hooks can `{:inject, msg}` to add context or
`{:transform, prompt}` to rewrite the user's message. See
[hooks reference](guides/hooks_reference.md).

**Five permission modes.** Add `:accept_edits` (auto-allow file
edits, still prompt for `bash`) and `:trusted` (skip prompts; with
optional `respect_denylist: false` for full YOLO) on top of the
existing `:plan` / `:default` / `:bypass_permissions`. The denylist
always wins, including in bypass — that's locked in a doctest. See
[permissions](guides/permissions.md).

**Subagents v2.** Define custom agents in `.exathena/agents/<name>.md`
with frontmatter (`tools`, `permissions`, `mode`, `isolation`); spawn
by name via `agent: "explore"`. Optional git-worktree isolation
creates an isolated checkout per subagent (with safety checks +
graceful fallback). Sidechain transcripts persist the full subagent
conversation to disk so the parent only spends tokens on the final
text. Three builtin definitions ship: `general`, `explore`, `plan`.
See [agents + subagents](guides/agents_subagents.md).

**Storage + checkpoint.** `ExAthena.Sessions.Store` is an
append-only event log behaviour with two stores: in-memory (default)
and ETS-buffered JSONL with periodic flush. Sessions emit
`:user_message` / `:assistant_message` / `:tool_result` events;
`Session.resume/2` rebuilds the message history from any store.
File-checkpoint snapshots fire before every `Edit` / `Write`, and
`Checkpoint.rewind/3` restores files + truncates the session log to
a chosen UUID. See [sessions + checkpoints](guides/sessions_and_checkpoints.md).

## Guides

- [Getting started](guides/getting_started.md)
- [Providers](guides/providers.md)
- [Gemini setup](guides/gemini.md)
- [Tool calls](guides/tool_calls.md)
- [The agent loop](guides/agent_loop.md)
- [Tools (incl. tool-result split)](guides/tools.md)
- [Memory + skills](guides/memory_and_skills.md) — v0.4
- [Compaction pipeline](guides/compaction_pipeline.md) — v0.4
- [Hooks reference](guides/hooks_reference.md) — v0.4
- [Permissions](guides/permissions.md) — v0.4
- [Agents + subagents](guides/agents_subagents.md) — v0.4
- [Sessions + checkpoints](guides/sessions_and_checkpoints.md) — v0.4

## License

Apache 2.0 — see [LICENSE](LICENSE).