Pixir Open Beta Quickstart

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Pixir's first open beta is a developer preview. The supported public surface is the Pixir runtime, terminal CLI, and ACP over stdio. Hex distribution, when used, installs the same CLI/ACP runtime and does not imply a stable public Elixir library API.

What You Need

  • Elixir compatible with mix.exs.
  • A local checkout of this repository for source installs, or Hex package access for escript installs.
  • Either ChatGPT subscription login through pixir login or an OPENAI_API_KEY.

See docs/adr/0016-open-beta-scope.md for the open beta scope and docs/adr/0025-hex-package-scope.md for the CLI/ACP-only Hex package contract.

Install From Hex

mix escript.install hex pixir
pixir --version
pixir help
pixir doctor --json

Install From Source

mix deps.get
mix escript.build
./pixir help
./pixir doctor --json

doctor is local-only and no-network. It checks the runtime version, source-install binary, workspace/session-log writability, local credential presence, config.json shape, and ACP command availability. It may create .pixir/sessions and remove a temporary probe file. It does not prove that the Provider accepts your selected model; use a smoke task for that.

After a Session exists, use local replay diagnostics when another agent, ACP client, or operator needs evidence about replay continuity. Use pixir for package installs and ./pixir for source checkouts:

pixir inspect-replay <session-id> --json
pixir diagnose session <session-id> --json

These commands read the local Log. They do not call the Provider.

Sign In

pixir login

Follow the printed device-code instructions. The subscription credential is stored under ~/.pixir/auth.json with local file permissions. As a fallback, set OPENAI_API_KEY.

Open Responses Profile (Experimental)

Pixir's default remains the chatgpt_codex Responses backend. Source-checkout users may explicitly select the first conservative open_responses HTTP/SSE profile in ~/.pixir/config.json:

{
  "model": "vendor-model",
  "responses_backend": {
    "mode": "open_responses",
    "responses_url": "https://vendor.invalid/v1/responses",
    "auth": {"policy": "bearer_env", "env_var": "VENDOR_API_KEY"}
  }
}

Use a real validated endpoint in local config; diagnostics retain only redacted route and auth summaries. Literal loopback HTTP may use {"policy":"none"}. Bearer credentials require HTTPS or literal loopback and are read only for the request.

The initial profile deliberately preserves store: false, uses HTTP/SSE only, adds the required type: "message" discriminator, omits optional cache/encrypted-reasoning and OpenAI-hosted-tool extensions, and rejects requested reasoning plus schema-valid nonportable streamed content. Its strict decoder covers the pinned Open Responses/WHATWG framing surface. Every known HTTP/SSE event is validated first against a checked-in module generated from the exact pinned OpenAPI closure (24 roots, 69 reachable schemas); runtime validation loads no schema, file, dependency, or network resource. Unknown event types stay opaque, while malformed known types fail before reduction. This is experimental bounded interoperability, not universal or full compliance. Explicitly certified custom Provider modules receive the active opaque backend selection but own their wire and inherit no Pixir conformance claim.

Runtime validation fails closed after depth 64 or 250,000 schema/instance evaluations. Consequently, a Draft-valid but adversarially large event may return the fixed validation_budget_exceeded reason instead of being reduced; this is an intentional denial-of-service bound, not a claim that the pinned schema rejected the event.

Maintainers can reproduce the generated subset and 14,235-row logical differential corpus from a local copy of the pinned OpenAPI, without network access. The checked-in corpus deduplicates canonical root events into independently reconstructable mutation recipes; its manifest pins both stored and expanded digests:

uv run python bin/generate-open-responses-schema \
  --input /path/to/pinned/public/openapi/openapi.json --check --json
uv run --with jsonschema python bin/verify-open-responses-schema-corpus \
  --input /path/to/pinned/public/openapi/openapi.json --json

From a source checkout, validate without credentials or network first:

mix pixir.smoke.open_responses --help
mix pixir.smoke.open_responses --dry-run --json

The opt-in live command makes at most two Provider calls, executes no model-selected tool, and writes a bounded redacted evidence envelope:

mix pixir.smoke.open_responses --json

Run A First Turn

From a project directory:

pixir --read-only "inspect this repo and summarize the architecture"

Pixir writes the model answer to stdout and activity/session details to stderr. Session Logs are stored under .pixir/sessions/ in the workspace and can be resumed:

pixir resume <session-id> "continue from there"

Reading One-Shot Results

One-shot runs (pixir "prompt" and pixir resume <id> "prompt") are a completion contract for scripts and orchestrators, not an interactive session:

  • stdout carries only the model's final report. If the transport delivers final text that never arrived as streamed deltas, Pixir still flushes it to stdout before exiting.
  • stderr carries activity, diagnostics, and the exact resume command (pixir resume <session-id> "...") on every terminal path, including idle timeout.
  • Exit codes: 0 answer delivered; 1 turn error; 6 turn completed without a final assistant message (an honest incomplete — stderr names the pixir diagnose session <session-id> --json command to inspect the Log); 124 idle timeout; 130 interrupted.

Read the final report from stdout; read everything about how the run went from stderr and the Log-backed diagnostics (diagnose, inspect-replay, tree).

Permission Modes

pixir --read-only "inspect this repo"
pixir --ask "make a small change and test it"

--read-only denies mutations. --ask prompts before writes and unsafe shell commands.

ACP Clients

Point an ACP client at the installed or built escript:

pixir acp

ACP is the beta UI transport contract. Pixir still executes tools internally and reports tool lifecycle through ACP updates.

Presenter Confidence

The open beta treats ACP clients and local dogfood presenters as operator surfaces over the same Pixir runtime. Local parity gauntlets have exercised CLI, T3 Code Pixir dogfood, and Zed ACP against the same source-built binary and workspace for simple answers, file reads, and bounded Subagent work.

Use that as developer-preview confidence, not as a strict UI parity claim. For any important presenter result, prefer Log-backed evidence: the visible answer, the matching .pixir/sessions/<session-id>.ndjson, inspect-replay, diagnose, and tree when Subagents are involved.

Subagents And Workflows

Pixir supports supervised Subagents and structural Workflows. For beta users, the honest contract is operational but narrow:

  • bounded Subagents run as supervised child Sessions and record durable terminal evidence;
  • wait_agent can return structured partial outcomes when only some children complete;
  • completed Subagents and Workflow steps may produce useful checkpoint bundles;
  • partial Workflow outcomes are not success;
  • timed-out, failed, cancelled, or detached children must be reported honestly with child ids, task-position children[].index when spawned from delegate tasks[], and actionable state;
  • direct CLI fanout and parent-led Subagent fanout are covered by the no-network fanout regression gauntlet;
  • long-running non-blocking Subagent status/result retrieval remains an experimental client UX surface, especially in ACP clients that choose their own presentation model.

Use mix pixir.bench.fanout_gauntlet --dry-run --json from a source checkout when you need reproducible evidence for those claims. The gauntlet is a correctness and honesty gate, not a performance benchmark.

For a copyable Codex/Claude Code style delegate call, see docs/examples/delegate-cli-live/. Its dry-run path is local-only; running without --dry-run uses the configured Provider.

Local Verification

For a package install, start with:

pixir doctor --json

For a source checkout, maintainers can run the broader local gate:

mix check

Networked smoke tasks are manual/opt-in and belong to source-checkout verification, not normal package use.

Pixir treats image attachments as durable local Session Resources. The original resource is local Pixir evidence; OpenAI input_image is only the Provider projection used when the Turn needs the image. Later Turns should replay descriptors or digests by default unless resource_view explicitly rehydrates the original image.

ACP resource_link blocks are also accepted as Session Resource descriptors. Readable local file:// links are copied into Pixir's local resource store; remote links are recorded as references but are not fetched automatically.

Provider-hosted Web Search is opt-in. It is not MCP and not a local browser tool: OpenAI runs the hosted search and Pixir records bounded source evidence in provider_usage.