@jev-harness/pi

Pi extension packaging TypeSafe Jev (System One) judgments: five fail-open tools, an append-only skill-router advisory, and Jev-driven verbatim compaction. Mirrors the OMP adapter; Pi and OMP share the same extension factory shape (export default function (pi: ExtensionAPI)).

Pi manifest field

Pi discovers extensions through the pi.extensions array in package.json — a list of paths (files or directories) resolved relative to the package root by Pi's extension loader (readPiManifest reads the pi object; resolveExtensionEntries resolves each entry; verified against @earendil-works/[email protected] sources). This package declares:

{ "pi": { "extensions": ["./src/extension.ts"] } }

The reference repo points at a directory (["./extensions"]); this package points at the entry file instead so the jiti module import Pi performs per loadExtensionModule resolves unambiguously (no directory-index guessing).

Source: https://github.com/joelhooks/pi-fast-jev-compaction — package.json ("pi": { "extensions": ["./extensions"] }) and extensions/pi-fast-jev-compaction.ts (default-export factory, session_before_compact returning { compaction: { summary, firstKeptEntryId, tokensBefore, details } }).

Install

From the Pi agent directory (global install):

# from a checkout of jev-harness
pi install ./packages/pi
# or by git URL once published
pi install git:github.com/Talya1412/jev-harness

For one run without installing:

pi -e ./packages/pi

Requires Node >= 20 (Pi itself targets Node 24.18; see the reference repo).

Environment

| Variable | Meaning | Default | | ------------------------ | ------------------------------------------------------------------------------------------------------- | ---------------------------------------- | | TYPESAFE_API_KEY | TypeSafe API key. Read on every call, never logged. All tools/hooks fail open without it. | (none — required) | | TYPESAFE_BASE_URL | Jev endpoint override. | core default (https://api.typesafe.ai) | | TYPESAFE_DEFAULT_MODEL | Jev model override. | core default (jev-latest) | | JEV_TIMEOUT_MS | Per-request timeout in ms. | 15000 | | OMP_JEV_KEEP_THRESHOLD | Shared with the OMP adapter: noul keep-scores below this on both call and result mark a pair stale. | 0.2 |

export TYPESAFE_API_KEY='...'

Tools

All five tools fail open: Jev errors resolve to advisory text, never throw.

• jev_ask — raw judgments over an arbitrary JSON state plus a questions map (noul / choice / score).
• jev_models — list Jev models available to the configured key.
• jev_route_skills — route a message to one skill (or none). Send skill descriptions, not bare names.
• jev_pick_tool — pick one tool (or none), with a confirmation flag for side-effecting choices. Does not execute anything.
• jev_browse_action — pick the next browser operation from a page snapshot. Does not execute anything.

Hooks

• session_before_compact — collects assistant tool-call / tool-result pairs (by toolCallId, capped at 40), asks two noul questions per pair (keep the call, keep the result), and returns verbatim compaction when at least one pair is stale on both scores: { compaction: { summary, firstKeptEntryId, tokensBefore, details } }. Returns undefined (Pi falls back to built-in summary) when there is no key, no complete pairs, nothing stale, or Jev fails.
• input — fire-and-forget skill-router advisory. Notifies when a registered tool looks relevant; never blocks, transforms, or handles input.

Assumptions

• No destructive tool_call gate: Pi's tool_call event only supports fail-closed blocking ({ block: true }), and per instructions a risky gate was omitted rather than shipped. jev_pick_tool exposes the confirmation signal to the model instead.
• Pi's CompactionResult has no shortSummary field (verified in @earendil-works/[email protected]: { summary, firstKeptEntryId, tokensBefore, estimatedTokensAfter?, usage?, details? }), so the OMP-adapter shortSummary is folded into details: { shortSummary, threshold, decisions }.
• input uses pi.getAllTools() (ExtensionAPI method) as the routing candidate set; the async judgment notifies via ctx.ui.notify.