para-open

Run the same prompt across many opencode models in parallel, then have a powerful "synthesizer" model (default: Claude Opus 4.7) read every model's tool transcript and final output and produce a single comparison report.

Useful for:

• Model evaluation — see how Claude vs GPT vs Gemini approach the same coding task on the same codebase.
• Best-of-N answers — when one model is wrong, another usually isn't; the synthesis report makes the disagreement visible.
• Research / dossiers — every run is captured to disk (prompt, raw event stream, file changes, derived status) so you can re-analyze later.

Install

npm install -g @himuglamuh/para-open

Requirements:

• Node ≥ 20
• opencode on PATH and at least one authenticated provider (opencode auth)
• Disk space — each model gets its own copy of the source dir under runs/<run>/<label>/workspace/. A 100MB repo × 6 models = 600MB per run. Use --no-source for prompt-only experiments.

Provider note: the default models.json ships three github-copilot/* models (Claude / GPT / Gemini families). They require a GitHub Copilot subscription. To mix in anthropic/* or openai/* direct-API models, edit models.json (see models.example.json for a longer Copilot catalog) and ensure opencode auth has the relevant credentials.

Usage

# inline prompt, runs against ./ as the source dir
para-open "Refactor foo.ts to use async/await and add a test."

# prompt from file
para-open --prompt-file ./prompt.md

# custom options
para-open --prompt-file p.md \
  --models ./models.json \
  --source-dir ./my-project \
  --out ./runs \
  --timeout 900 \
  --concurrency 4 \
  --no-synth

# re-synthesize an existing run (rebuilds dossier + report.md)
para-open synth ./runs/2026-04-17T16-20-05Z-4a6b57d1

# ask a follow-up question against the synthesizer's session
para-open ask ./runs/2026-04-17T16-20-05Z-4a6b57d1 \
  "Elaborate on why opus-4.7 hit the content filter."

Flags

Subcommands

• synth <run-root> — rebuild dossier.md and report.md for an existing run. Refreshes each model's status/analysis from stdout.jsonl before synthesis. Captures the synthesizer's session ID to synthesis.session.json so follow-ups can resume it.
• ask <run-root> "<question>" — ask a follow-up against the captured synthesis session. Uses opencode run -s <session> for conversational continuity. Falls back to attaching dossier.md + report.md if no session is recorded.

Answers land in <run-root>/followups/NNN.{question.md,stdout.jsonl,stderr.log,answer.md}.

Note on resumed-session length: Some providers (notably Copilot) give noticeably shorter answers when continuing a session that already absorbed a large dossier. If you want a long, structured follow-up, pass --fresh — that starts a new session and re-attaches dossier.md + report.md.

Output layout

runs/<UTC-ISO>-<shortid>/
├── prompt.txt
├── index.json
├── dossier.md                # consolidated input handed to the synthesizer
├── report.md                 # final comparison, written by the synthesizer
├── synthesis.stdout.jsonl
├── synthesis.stderr.log
├── synthesis.session.json    # captured session id for follow-ups
├── followups/                # created on first `ask`
│   └── 001.{question,answer}.md + stdout.jsonl / stderr.log
├── <label>/
│   ├── workspace/            # isolated copy of --source-dir (post-run state)
│   ├── stdout.jsonl
│   ├── stderr.log
│   ├── final.md              # extracted final assistant message (with status header if non-ok)
│   ├── changes.txt           # files the model modified/created
│   └── meta.json             # model id, timing, exit code, signal, status, analysis
└── ...

Model config

models.json schema:

{
  "synthesizer": "github-copilot/claude-opus-4.7",
  "models": [
    { "id": "github-copilot/claude-sonnet-4.5", "label": "claude-sonnet-4.5" },
    { "id": "github-copilot/gpt-5.2",          "label": "gpt-5.2" },
    { "id": "github-copilot/gemini-2.5-pro",   "label": "gemini-2.5-pro" }
  ]
}

Labels are optional (auto-slugified from id if omitted). See models.example.json for a larger Copilot catalog you can copy from.

Bootstrapping models.json

Rather than hand-writing the file, run para-open init-models to generate one from the providers you've already authenticated with opencode:

# Interactive picker (default when run from a TTY)
para-open init-models

# Every authenticated model
para-open init-models --all

# All models from one provider
para-open init-models --provider anthropic

# Glob-match (any number of patterns)
para-open init-models --filter '*opus*' '*gpt-5*'

# Curated presets (will go stale as new model versions ship)
para-open init-models --preset frontier        # one strong model per family
para-open init-models --preset cheap           # haiku / mini / flash tier
para-open init-models --preset claude-vs-gpt   # head-to-head pair

# Pin the synthesizer explicitly
para-open init-models --all --synth openai/gpt-5

# Print to stdout instead of writing a file
para-open init-models --preset frontier --stdout

# Overwrite an existing models.json
para-open init-models --all --force

The synthesizer defaults to claude-opus-4.7 when available, falling back to sonnet variants then gpt-5. Override with --synth <id>.

Run status

Each run is classified into a status that the dossier, summary table, and final.md warning header all surface:

The synthesizer is explicitly told to treat non-ok runs as failures and to describe what the model was doing (via the tool transcript in the dossier) when it aborted.

Examples

See examples/ for ready-to-run scenarios:

• examples/bug-fix/ — find and fix an off-by-one bug.
• examples/refactor/ — convert a callback-chain to async/await.
• examples/greenfield/ — implement a small CLI tool from scratch.

Each scenario has a prompt.md and a src/ you can pass to --source-dir.

License

MIT