Imp v0.4.0

Imp v0.4.0

Imp is a framework for typed, optimizable language-model programs on the BEAM.
Declare a task as named inputs and outputs, call it like any other Elixir
program, measure it on examples, compile it with an optimizer, and run the
selected program under OTP.

This release absorbs the protocol adapters that previously lived on main
only, and changes three published shapes. It is 0.4.0 rather than a patch
because a program written against v0.3.2 can need edits.

Install

v0.4.0 is a Git source release from a public repository; no credentials are
required.

{:imp, github: "deepfates/imp", tag: "v0.4.0"}

Imp is not published to Hex. Use a path dependency only while developing
against a local checkout.

ExMCP is declared runtime: false, so an OTP release that uses Imp.ACP or
Imp.MCP must list applications: [ex_mcp: :load] in its release
definition; see protocol runtime in
releases.
Ordinary Imp startup starts no protocol endpoint.

Headline changes

• Imp.ACP and Imp.MCP.connect/2 are in the tag. The separate imp_acp
  package is retired with no compatibility shim: a consumer that depended on
  it now depends on imp alone. Imp.MCP.connect/2 also gains OAuth
  credentials for remote HTTP servers (Imp.MCP.OAuth), bearer_env
  descriptor auth, on_failure: :drop with an unavailable list, and a
  per-dial timeout.
• :reasoning_effort is the one reasoning option on Imp.Clients.ReqLLM.
  :openrouter_reasoning is gone; the wire encoding is the separate
  :openrouter_reasoning_wire.
• ReActV2 sends the tool roster natively and no longer declares a tools
  input field or writes its instructions into signature.instructions. Loop
  guidance travels to the adapter through :adapter_opts.
• The :model_response event's metadata.cost is a plain USD float or nil,
  with any provider breakdown under metadata.billing.
• Structured values in a prompt render complete, the way DSPy renders a dict,
  instead of a truncated inspect/1.

Breaking changes from v0.3.2

• Replace openrouter_reasoning: ... with reasoning_effort: .... Saved
  programs allowlist :reasoning_effort and :openrouter_reasoning_wire in
  its place, so rebuild artifacts that carried the old key.
• A caller that passed or read ReActV2's tools input field no longer has
  one; the roster is sent natively.
• A host that read metadata.cost as a provider billing map reads a number
  now, and finds the map under metadata.billing when the provider sent one.

Upgrade path

1. Rename the reasoning option and rebuild saved artifacts with 0.4.0.
2. Drop any tools handling around ReActV2.
3. Sum spend from metadata.cost as a number.
4. If you depended on {:imp, github: "deepfates/imp", branch: "main"} for the
   adapters, move to the tag.
5. Run your held-out evaluation and application smoke test against the tagged
   dependency.

New in this release: Benchmarks
and its results table
carry every number this repository publishes with the command that produces it,
and the ticket-routing rows were re-measured live for this release, a month
after the first run, with both runs recorded.

The CHANGELOG records every user-visible change in this
release. Generated module documentation is the complete API reference. Start
with Imp, Imp.Signature, Imp.Module, Imp.Evaluate, Imp.Optimizer,
Imp.ACP, Imp.MCP, and Imp.Telemetry.