SoL-PiG

SoL-PiG brings SoL-Pi's four token-efficiency mechanisms to PiG as a native Go extension. It is a port of SoL-Pi, which NVIDIA released under the MIT license for the Pi coding agent. SoL-PiG is not an NVIDIA or PiG project.

Spend less without making the agent do less useful work. The four mechanisms are Action Fusion, ObservationPack, the Evidence-Preserving Reducer and Online Context Compact. Each is opt-in and disabled by default. The texts the model sees (tool names, descriptions, placeholders, receipts, reminders) are byte-identical to SoL-Pi at commit 2195680, apart from the differences listed in docs/compatibility.md; only the product name shown to you is SoL-PiG.

Why Go

SoL-Pi is a TypeScript extension, so every PiG instance that loads it also starts a Node process. SoL-PiG runs in PiG's Go extension runner instead. Idle footprint. The first three rows are 10 idle instances, measured before the port was written; the method used then was not recorded. SoL-PiG was measured as one instance on macOS with footprint (step 3 of scripts/live/verify.sh), and its 10-instance figure is that times ten:

| Setup | 10 instances | |---|---| | bare PiG | 116 MiB | | PiG + a minimal Go extension | 202 MiB | | PiG + SoL-Pi (Node) | 1,407 MiB | | PiG + SoL-PiG | 33 MiB for one instance (step 3 of scripts/live/verify.sh, across its two processes: pig and the extension runner); 10 × that ≈ 330 MiB, not measured as 10 instances |

Step 3 of scripts/live/verify.sh measures one instance on your machine (footprint on macOS, RSS elsewhere) and prints, for example, 33 MiB across 2 processes (pig + extension runner).

Requirements

• PiG 0.5.3 or newer
• Go 1.26 or newer on PATH whenever PiG builds the extension (first load, and any rebuild). The build is cached afterwards; see the first-run note in docs/verification.md.
• No Node.js or npm is needed to run SoL-PiG. PiG itself may need them, depending on how you install it, and scripts/live/sol-pi-under-pig.sh needs Node.

Install

pig install npm:sol-pig

Or straight from GitHub:

pig install git:github.com/balcsida/SoL-PiG

From a local checkout:

git clone https://github.com/balcsida/SoL-PiG
pig install /path/to/SoL-PiG

Install SoL-PiG or SoL-Pi in a PiG, not both: they register the same tools and share the runtime directory. Both read the same sol-pi.json, so an existing SoL-Pi configuration carries over unchanged. Remove SoL-Pi's entry from PiG's packages setting before installing SoL-PiG; nothing stops both from loading.

Configure

This conservative configuration enables only the two local mechanisms that make no extra model calls and do not stop an active run:

{
  "version": 1,
  "actionFusion": true,
  "observationPack": true,
  "evidencePreservingReducer": false,
  "onlineContextCompact": false,
  "cacheWriteReadRatio": 12.5
}

SoL-PiG reads sol-pi.json from the directories PiG reports to the extension, in this order:

1. <project>/<config dir>/sol-pi.json, when the project is trusted and the file exists. <project> is the session's working directory; <config dir> is .pig (.pi when PiG shares Pi's tree).
2. <agent dir>/sol-pi.json, where the agent directory is the one the PiG host reports, normally ~/.pig/agent.

With neither file, every mechanism stays off. The project file replaces the global one; they are never merged. An invalid file stops the extension from loading, with a direct error. sol-pi.example.json lists every key; docs/configuration.md has the schema, defaults and validation messages.

• version: must be 1.
• actionFusion, observationPack, evidencePreservingReducer, onlineContextCompact: booleans, default false.
• evidencePreservingReducerProvider, evidencePreservingReducerModel: the PiG model the reducer calls, default openai-codex and gpt-5.6-luna; credentials stay in PiG.
• cacheWriteReadRatio: how much a cache write costs relative to a read in Online Context Compact's economic check, default 12.5.

Mechanisms

| Mechanism | What changes for the model and you | Key | |---|---|---| | Action Fusion | edit and write accept an optional then_run command that runs after the mutation, in the same tool call, through PiG's bash tool. | actionFusion | | ObservationPack | Successful, text-only tool results over 10 KiB (not reducer receipts) are sent in full twice, then replaced in later requests by a short placeholder; the model reads exact slices back with the obs_recall tool. | observationPack | | Evidence-Preserving Reducer | Long output of diagnostic commands (make, go test, cargo, pytest, lean and similar) becomes a compact receipt written by a reducer model, accepted only when every quote matches the archived log byte for byte. The default route works only if PiG has that model and your login for it. Otherwise each eligible log is archived locally, the tool output passes through unchanged and the journal records a fallback (reducer-model-unavailable, model-response-error, model-call-exception or model-call-timeout). Point evidencePreservingReducerProvider/evidencePreservingReducerModel at a model you have. | evidencePreservingReducer | | Online Context Compact | Adds an update_plan tool. Completing a plan step is a possible compaction point. Window pressure (context within the reserve of the window) forces PiG's native compaction there, regardless of the economics and the cooldown, when it would save tokens; otherwise an economic check decides. A selected boundary stops the active run and resumes it with a hidden reminder. | onlineContextCompact |

Seeing it work

In the TUI, each saving shows a notification and, for four seconds, a status line, worded as in SoL-Pi:

⚡ SoL-PiG · Observation Pack
Money saved · 2,531 context tokens avoided

The saving text is 1 model round-trip avoided (Action Fusion, on a succeeded then_run in a non-nested call), N context tokens avoided (ObservationPack, at the first placeholder per observation), a size removed from future prompts (the reducer, labelled "Luna Delegating", when a receipt is applied) and N context tokens removed (Online Context Compact, only when tokens were removed). Sizes render as B, KiB or MiB. The renderers of obs_recall and update_plan carry the same two-line banner. A compaction that was skipped shows Online compaction skipped: … as a warning. Other modes (print, JSON, RPC) stay silent.

scripts/live/verify.sh checks all four mechanisms inside a real PiG process: seven steps with PiG's fake provider and a scripted loopback endpoint, zero spend, no credentials. See docs/verification.md.

Storage and security

ObservationPack and the reducer archive source material under the session's runtime root, <session dir>/sol-pi/<session id>/:

observation-pack/              objects/<id>.txt, ledger.jsonl
evidence-preserving-reducer/   objects/<xx>/<sha256>.txt

A session without a directory (--no-session) gets a private temporary directory instead, sol-pi-<session id>-… under the system temp directory. Archives stay local and are not deleted automatically. The reducer may send eligible logs to its configured model. Read SECURITY.md before enabling it.

Documentation

| Document | Purpose | |---|---| | docs/configuration.md | Sources, schema, defaults, runtime inputs | | docs/compatibility.md | PiG APIs used and every difference from SoL-Pi | | docs/verification.md | Live results on PiG 0.5.3 | | SECURITY.md | Local storage, remote reduction, then_run, reporting | | CHANGELOG.md | Release notes | | UPSTREAM.md | Which file ports which SoL-Pi or PiG source, at which commit |

Development

Run each command from the repository root:

(cd extensions/sol-pig && go vet ./... && go test ./...)  # unit and fake-host tests, zero spend
scripts/live/verify.sh                                    # real pig: fake provider + scripted endpoint, zero spend
scripts/live/sol-pi-under-pig.sh                          # pre-check: SoL-Pi itself under PiG (needs Node >= 22.19, npm, network)
pig install "$PWD" --validate-only --json                 # does PiG accept the package?

The live scripts need pig and go on PATH; they write under scripts/live/work/ (git-ignored) unless you pass a work directory. .github/workflows/ci.yml runs the Go checks, the scripted endpoint's tests and scripts/live/verify.sh against PiG 0.5.3 on every pull request and push to main.

License

MIT. SoL-PiG derives from SoL-Pi (Copyright © 2026 NVIDIA Corporation & Affiliates, MIT) and copies one normaliser from PiG (Michael Kinsy, MIT); see LICENSE and THIRD_PARTY_NOTICES.md. The research behind the mechanisms is described in the SoL-Pi paper and blog.