Imp v0.8.1

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Imp is a framework for typed, optimizable language-model programs on the BEAM. This patch makes ACP tool results readable and truthful about omitted content, and fixes local socket framing for large permitted JSON messages. It changes neither model-facing behavior nor MCP, dependency pins, or stored schemas.

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 0.8.0

  • ACP now labels tool output omitted by the capture limit instead of printing nil. Genuine nil renders as null; empty results, failures and completed calls remain distinct. Structured output is JSON and errors use the same readable wording the model receives. A preview exceeding 32,768 UTF-8 bytes is explicitly cut; capture limits are unchanged. A host with full native records can supply its own bounded view and recovery coordinates.
  • Local ACP listener and connecting sockets keep valid large JSON lines whole. The socket buffer follows the existing frame cap, including the newline; frames above the configured cap are still refused. This fixes frames split at the default driver buffer even though they were within the cap.

Keep {:imp, "~> 0.8"}, run mix deps.update imp, and commit mix.lock. No data migration is needed. This does not reconstruct content omitted from historical ACP transcripts, and does not add a full-result retrieval endpoint. Rollback means restoring the previous dependency lock and application release; it restores the old display/framing defects too. Provider-free tests cover capture distinctions, UTF-8 bounds, real socket fragmentation, consecutive frames and oversize refusal. See the changelog for older changes.

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.