Imp v0.11.0

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Imp is a framework for typed, optimizable language-model programs on the BEAM. This release stops Imp from returning a provider's content-filter message as if the model had written it. A completion the filter stopped is now a failed request, so what a caller receives for that response changes from a completion to an error. Under Imp's versioning rule that makes it a minor release rather than a patch, even though it is a fix.

This is also the first release published to Hex by CI from its tag, after every gate passed on the tagged commit.

Install

{:imp, "~> 0.11"}

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 0.10

Change the Imp dependency to {:imp, "~> 0.11"}, run mix deps.update imp, and commit mix.lock. (A two-part requirement such as ~> 0.10 allows any later 0.x version, so mix deps.update imp under it also takes 0.11. To stay on 0.10 releases only, write ~> 0.10.0.) No data migration is needed.

  • A content-filtered completion is a failed request. When a provider ends a non-streamed completion with finish_reason: :content_filter, Imp.Clients.ReqLLM returns {:error, %Imp.LMError{retryable: false}} instead of {:ok, completion}. Some providers put the filter's own message in the content (OpenRouter, for example, sends "The request was rejected because it was considered high risk"), and before this release a program read that text as the model's answer: a prediction could parse it, a ReAct loop could finish with it, and an optimizer could score it. The error's message is "API request failed: the provider's content filter stopped the completion: " followed by the provider's text, and its reason is a ReqLLM.Error.API.Request whose response_body holds "finish_reason" and "content". Migration: Imp.Predict, ReAct and other callers now handle a failed LM call where they handled a completion. A host that recognised the filter by its text, or by finish_reason on the completion, matches the Imp.LMError instead and can remove its own check. A host that retries every Imp.LMError should honour retryable, since the same request is likely to be filtered again.

Rollback means restoring the previous dependency requirement, lock and application release; it brings back the filter's text returned as a completion. A provider-free test with a ReqLLM stub asserts the error for a :content_filter response; this release does not establish which providers send :content_filter or what text each one puts in the content. See the changelog for every change.

Known limits

  • The usage map (:usage on the :model_response event, Imp.Usage, Imp.Prediction.get_lm_usage/1) is ReqLLM's, unchanged. Its :cost and :total_cost are ReqLLM's catalog estimate, not a charge, for streamed and non-streamed calls alike, 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.
  • Tool images reach the model as user messages after the turn's tool responses, labelled with the call, not nested in the tool result, even for providers that accept images in tool results. Only MCP text and image blocks are converted; other block types stay text, image URLs in text are never fetched, and the selected model must accept image input of that format and size.
  • ATIF's extra.seen_by_model and the read-as content come from matching a tool message in the next captured request. A result that request does not carry, including one that ended the run, keeps the tool's own output and is marked unseen. agent.tool_definitions comes only from :tools_sent events, and final_metrics totals are left out when any response lacks that figure.
  • A streamed completion that the provider's content filter stops still ends as a completion: the stream's finish_reason is :content_filter and the filter's text has already arrived as chunks. Only non-streamed requests turn it into an Imp.LMError.
  • 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.