Imp v0.8.0

Copy Markdown View Source

Imp is a framework for typed, optimizable language-model programs on the BEAM. This release makes a ReActV2 agent's text completion field match its task, preserves omitted output limits on OpenRouter requests, and includes the Finch connection-timeout fix. The model-facing completion contract changes, so this is a minor release rather than a patch.

Install

{:imp, "~> 0.8"}

Every dependency comes from Hex. Use a path dependency only while developing against a local checkout.

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

Changes and upgrading from 0.7

  • For a task with one unconstrained text output, ReActV2 now asks the model for that output by name and carries its description into the step signature. A task whose output is answer asks for answer instead of next_thought. Update scripted model responses and custom step renderers to use the task output name. Typed and constrained tasks still complete through submit. Saved step history and legacy demonstrations keep working; a loaded agent derives the new contract from its task signature. The stored internal step fields remain compatible. A nonempty answer still means completion; prose such as "No reply" is not interpreted as silence.
  • OpenRouter requests with no explicit output-token limit omit that limit on the wire, rather than reserving the model catalog's maximum output. This avoids rejecting usable prompts for exceeding the total context window. Both ordinary and streamed requests retain caller-supplied limits. Other providers are unchanged.
  • Imp now requires Finch 0.24, which closes an HTTP/1 connection after a request timeout. Its lock uses Mint 1.11.0, removing the three Mint advisories that accompanied the previous 1.10.1 hold. Remove any application dependency added solely to hold Mint at 1.10.1, then update Finch, Mint and hpax along with Imp. The reason for that hold no longer applies.

Change the Imp dependency to {:imp, "~> 0.8"}, resolve dependencies and commit mix.lock. See the changelog for earlier migration notes. Provider-free tests exercise these mechanics; this release does not establish how any particular model will respond to the revised completion contract.

Known limits

  • Imp.Usage does not see streamed calls: they run in a separate process, so usage tracked around Imp.collect or a streamed Imp.call is empty. Read usage from the run's :model_response events.
  • The usage map (:usage on the :model_response event, Imp.Usage, Imp.Prediction.get_lm_usage/1) is ReqLLM's, unchanged. For a non-streamed call its :cost and :total_cost are ReqLLM's catalog estimate, not a charge, and OpenRouter's charge is its "cost". Read money from cost and estimated_cost.
  • An error the provider sends inside a stream has status nil and retryable: true, because ReqLLM's stream decoder keeps only its message; the same error in a non-streamed response may carry a status that says not to retry.
  • A flat two-element name-first list that is not itself an element of a list (at the top level, in a tuple, or under a key that is not a credential name), such as ["password", "hunter2"], is not redacted, where 0.5.0 redacted it. Such a list is read as a key and value only as an element of a list, so that lists of names such as with_inputs([:api_key, :question]) survive saving.
  • The GEPA, SIMBA, MIPROv2, InferRules and random-search checkpoints redact their failure reasons but otherwise hold the resume state as it is: GEPA's candidates, evaluation cache, proposed instructions and reflection data, and the others' instructions, demos and scores. Fast-Slow and Playbook checkpoints likewise hold their prompts, rollouts and playbooks. Treat checkpoint files as sensitive.
  • A ReActV2 step whose prose quotes its own field names (a JSON object with next_thought or tool_calls keys, a [[ ## field ## ]] line, a <next_thought> tag) is not read as prose and goes to the JSON fallback, which usually costs one more call. If the model repeats the same reply, the step ends :incomplete. Beside native tool calls, such a thought becomes nil; the calls still run.
  • When a streamed ReqLLM request fails, ReqLLM's own warning log prints the error with its response headers. Imp strips them from the error it returns, but cannot change that log line.
  • In command output, a Bearer token of 12 to 15 characters, or one with no digit, is shown when more text or a newline follows it. 0.5.0's command pipeline hid any such token of 12 or more characters.
  • A GEPA checkpoint taken between preparing and starting a full validation resumes by rejecting that candidate, as before.

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.