SoL-Pi: pricing, features, alternatives

SoL-Pi is NVIDIA's standalone efficiency pack for the Pi coding-agent harness. The research page is nvlabs.github.io/SoL-Pi. The repo NVlabs/SoL-Pi is MIT, created 2026-09-02, TypeScript. On 2026-09-11 GitHub listed 340 stars and 17 forks, last push 2026-09-09. r/LocalLLaMA hot the same week framed it as a Pi extension from scaled auto-research loops. README: not an official Pi distribution; it imports public Pi APIs and does not vendor Pi source.

Compare Pi if you only needed the base harness, DeepSeek Harness if you wanted DeepSeek's runtime, or Claude Code if you wanted Anthropic's CLI instead of a Pi plugin.

Key Features

Action Fusion: an edit/write plus its follow-up validation command in one tool call, so the model skips the middle turn.
ObservationPack: large tool output becomes a handle plus excerpt, with paged recall of the archived body.
Evidence-Preserving Reducer: a cheaper reader may compress a long log only when every quoted line matches the archive. Fail-open: a bad receipt leaves the original result.
Online Context Compact: completed plan steps become compaction candidates; after a successful compact, Pi continues in a new turn.

Limitation: 340 stars is a heat signal, not an audit. Every mechanism is disabled until you set sol-pi.json. Evidence-Preserving Reducer can send log text to a configured reducer model; README says read SECURITY.md first. The blog's dollar-per-hour savings use official API-equivalent pricing on EdgeBench, not your bill.

Use Cases

Pi users on long EdgeBench-style runs who want fewer tokens without swapping the harness.
Teams that will keep Pi 0.84.2 (the tested peer) and opt in two local mechanisms first.
People who should use Pi alone if they do not want extra local archives or a reducer model.

Pricing

Piece	Price	Notes from first-party pages 2026-09-11
SoL-Pi extension	$0	MIT. About 340 stars.
Pi host	$0 software; you pay the model API	README pins `@earendil-works/pi-coding-agent@0.84.2`.
EdgeBench vs Pi	About one-third lower API-equivalent cost	Blog: 45-49% fewer tokens vs Pi; 50-54% lower list-price cost vs native Codex/Claude Code harnesses. Score stays about 94% of Pi.

Getting Started

Node.js 22.19+. Install npm install --global @earendil-works/pi-coding-agent@0.84.2.
pi install git:github.com/NVlabs/SoL-Pi (or --local --approve for one repo).
Write .pi/sol-pi.json or ~/.pi/agent/sol-pi.json. A conservative start is actionFusion and observationPack true, reducer and compact false.
Confirm with the repo's scripts/check-sol-pi-config.mjs if you enable everything.

First-party resource: the SoL-Pi blog.

Frequently Asked Questions

Does this fork Pi?

No. README: no Pi patches, no vendored Pi tree. Pi stays upstream.

Are the four mechanisms on by default?

No. Missing config keeps all four off.

Can NVIDIA take a patch from me?

README: external code contributions are not accepted now. Bug and private security reports still go through CONTRIBUTING.md and SECURITY.md.

Alternatives

Pi: the host harness SoL-Pi plugs into.
DeepSeek Harness: another MIT agent runtime, not a Pi plugin.
Claude Code: hosted CLI if you are not on Pi.

Tips

Quote MIT, 340 stars, Pi 0.84.2, and opt-in defaults from pages checked 2026-09-11.
Do not enable the reducer on logs that must stay local.
Project .pi/sol-pi.json wins over ~/.pi/agent/sol-pi.json; they are not merged.

Conclusion

SoL-Pi is the NVIDIA MIT pack r/LocalLLaMA pointed Pi users at: four efficiency mechanisms, all off until you say so. Start at the blog or GitHub. If you only needed the agent, open Pi first.