hosts: add pi (pi.dev) and oh-my-pi (omp) support

[soydachi]

What

Adds pi (pi.dev, @earendil-works/pi-coding-agent) and oh-my-pi / omp as instruction hosts, closing #402.

pi and omp already get two of graft's four channels for free:

Channel	Status on pi/omp before this PR
Orientation (AGENTS.md)	already works — both load AGENTS.md natively (candidate order verified in pi-coding-agent 0.85.1)
MCP tools (.mcp.json)	already works — omp reads it natively; pi via pi-mcp-adapter or host-config discovery
Per-prompt retrieval	missing
Statusline	missing

How

pi and omp share one extension API (omp is a pi fork; omp's hook runner loads .omp/hooks/pre/*.ts factories, pi auto-discovers .pi/extensions/*.ts). One extension file serves both hosts:

src/pi/graft-extension.ts (new, single source of truth — graft init copies it to both repo-local paths):

• before_agent_start (≈ Claude's UserPromptSubmit): runs graft ask --json --source on the prompt (8s budget, never blocks the turn) and injects a pointers-only pack behind the same gates as graft's own relevantRetrieval() — STRONG_FLOOR 0.1 / HIGH_FLOOR 0.5 on lexical coverage, weak matches get at most 2 nudges per session, and an injected pointer is never injected twice (novelty memory capped at 40).
• tool_result on edit/write: flips a stale flag; the [graft] graph is stale — run graft build note ships on the next turn's injection rather than clobbering the tool result. Same one-line posture as the Claude PostToolUse hook.
• turn_end → ctx.ui.setStatus("graft", …): the statusline bar — graft · N nodes / M edges · ✓ synced · ~X tok saved — preferring graft/.cache/stats.json and falling back to graft/.graph/wiring.json, the same posture as resolveStats() in the Claude statusline.
• Honesty rules carried over: the pack is pointers-only (~100 tok) so the saved-tokens credit is baselineChars/4 − pack, never the full baseline; a no-op outside graft/ repos.

src/hosts/pi-omp.ts (new): targets, detection (~/.pi, ~/.omp, mirroring the other CLIs' config-dir probes), and the install, which reuses writeOwned so a re-init reports unchanged instead of overwriting. Two copies, no symlinks: omp's scanner reads only .omp/hooks/pre/, pi only .pi/extensions/, and symlinks break repo packaging.

Registry: pi and omp entries render AGENTS.md via the existing instructionBody — no new instruction format.

Telemetry: 'pi' | 'omp' added to the AgentHost enum. The allowlist stays closed — without this, host attribution for the new surfaces would have to ship a free-form string, which the contract exists to prevent.

Init: the extension writes land as ConfigWrite in the hooks result, so --dry-run, the picker, and the actual run can't drift apart (the plan-vs-run consistency test enforces it).

Verification

• Full suite: 1221 pass, 0 fail (npm test), tsc --noEmit clean.
• End-to-end on a clean repo with graft init --no-build --agents pi --agents omp: AGENTS.md section + both extension paths written; pi -p (0.85.1) and omp -p --no-session (18.2.0) both inject correct packs, savedTokens accrues in the session file, and the statusline renders from the wiring.json fallback.
• Extension file contains no network calls, no env reads, no machine paths — a spawnSync("graft", …) plus local reads, nothing else.

Closes #402

[trailhq-graft]

🌱 graft blast radius

3 areas changed → 6 areas can be affected. 18 dependent symbols, depth 2.
Tests: no test reaches Extension Grafting; 1 area updated its tests.
Tag: @anirudhkumar-nanonets — 8 of 9 areas · @shhdwi — 5 of 9 areas

flowchart TB
  A0(("Host Integration<br/>6 symbols"))
  A1(("CLI Wiring<br/>6 symbols"))
  A2(("Claude Initialization<br/>2 symbols"))
  A3(("Brain Connection<br/>2 symbols"))
  A4(("MCP Server<br/>1 symbol"))
  AX(("1 smaller area<br/>1 symbol"))
  classDef reached fill:#D9EDF3,stroke:#3AA7C9,stroke-width:1.5px,color:#0E313C;
  class A0,A1,A2,A3,A4 reached;
  classDef tail fill:#EEF2F3,stroke:#9AA4A9,stroke-width:1px,color:#3A4247;
  class AX tail;

Loading

Can be affected	Symbols	Nearest hop	Reached from
Host Integration	6	src/hosts/retract.ts:L1-L500 retract.ts — imports, depth 1	Host Setup
CLI Wiring	6	src/cli.ts:L1088-L1173 wireTarget — calls, depth 1	Host Setup
Claude Initialization	2	src/claude/hooks.ts:L1-L463 hooks.ts — imports, depth 2	Host Setup
Brain Connection	2	src/brain/wire.ts:L1-L148 wire.ts — imports, depth 1	Host Setup
MCP Server	1	src/mcp/server.ts:L1-L152 server.ts — imports, depth 2	Host Setup
Event Tracking	1	src/telemetry/track.ts:L1-L156 track.ts — imports, depth 2	Host Setup

Who knows this code — 2 people across 9 areas

Area	Who knows it
Host Setup · changed	@shhdwi — 6 commits, last 1mo ago · @anirudhkumar-nanonets — 2 commits, last 14d ago
Telemetry Contract · changed	@anirudhkumar-nanonets — 3 commits, last 15d ago
Host Integration · affected	@shhdwi — 7 commits, last 1mo ago · @anirudhkumar-nanonets — 6 commits, last 5d ago
CLI Wiring · affected	@anirudhkumar-nanonets — 40 commits, last 5d ago · @shhdwi — 23 commits, last 1mo ago
Claude Initialization · affected	@anirudhkumar-nanonets — 17 commits, last 13d ago · @shhdwi — 11 commits, last 1mo ago
Brain Connection · affected	@anirudhkumar-nanonets — 1 commit, last 5d ago
MCP Server · affected	@anirudhkumar-nanonets — 5 commits, last 14d ago · @shhdwi — 2 commits, last 2mo ago
Event Tracking · affected	@anirudhkumar-nanonets — 2 commits, last 15d ago
…1 further area

Ownership is git history over each area's own files, weighted towards recent work (120-day half-life). Merge commits and bots are dropped, and you are dropped from your own PR. A name with no @ has no GitHub handle in its commit email — tag them by hand, or add a .mailmap entry. A suggestion from history, not a CODEOWNERS rule.

All 18 dependent symbols, grouped by area

Host Integration — 6 symbols in 6 files

• src/hosts/retract.ts:L1-L500 — retract.ts (imports, depth 1)
  4: * `init` is additive — it writes the files the *currently selected* hosts need
• src/hosts/antigravity.ts:L1-L47 — antigravity.ts (imports, depth 2)
  5: * `~/.gemini/skills/`. graft's skill card is the same one Claude Code and AdaL get;
• src/hosts/claude-global.ts:L1-L126 — claude-global.ts (imports, depth 2)
  5: * Why this exists. Everything `graft init` writes for Claude Code lands *in* the
• src/hosts/codex-hooks.ts:L1-L91 — codex-hooks.ts (imports, depth 2)
  10: import type { PlannedWrite } from './plan.js';
• src/hosts/cursor-hooks.ts:L1-L110 — cursor-hooks.ts (imports, depth 2)
  ```8: * .cursor/hooks/. That matches graft's Cursor-only posture — a `--no-global````
• src/hosts/mcp-config.ts:L1-L235 — mcp-config.ts (imports, depth 2)
  14: import type { PlannedWrite } from './plan.js';

CLI Wiring — 6 symbols in 4 files

• src/cli.ts:L1088-L1173 — wireTarget (calls, depth 1)
  1094: plan: ReturnType<typeof planInit>;
• src/cli.ts:L1-L1407 — cli.ts (calls, depth 1)
  18: import { runHostsInit } from "./hosts/init.js";
• src/upkeep-run.ts:L42-L51 — rewriteWiring (calls, depth 1)
  50: runHostsInit(repo, { agents: others, global: opts.global, mcp: opts.mcp, hooks: opts.hooks });
• src/upkeep.ts:L1-L333 — upkeep.ts (imports, depth 1)
  11: * 2. **Wiring staleness** — `graft init` copies hooks, shims, skill text and
• src/cli-picker.ts:L1-L385 — cli-picker.ts (imports, depth 2)
  2: * `graft init`'s agent picker and `--dry-run` plan printer.
• src/upkeep-run.ts:L1-L82 — upkeep-run.ts (imports, depth 2)
  9: import { runHostsInit } from './hosts/init.js';

Claude Initialization — 2 symbols in 2 files

• src/claude/hooks.ts:L1-L463 — hooks.ts (imports, depth 2)
  6: import { formatBlastRadius, relevantRetrieval, formatOrientation } from './format.js';
• src/claude/init.ts:L1-L105 — init.ts (imports, depth 2)
  12: import type { PlannedWrite } from '../hosts/plan.js';

Brain Connection — 2 symbols in 2 files

• src/brain/wire.ts:L1-L148 — wire.ts (imports, depth 1)
  7: * one: the repo-wide conventions, sitting in `AGENTS.md` / `CLAUDE.md` /
• src/brain/connect.ts:L1-L111 — connect.ts (imports, depth 2)

MCP Server — 1 symbol in 1 file

• src/mcp/server.ts:L1-L152 — server.ts (imports, depth 2)
  74: // refreshes rule files an older `graft init` wrote, and kicks off the cached

Event Tracking — 1 symbol in 1 file

• src/telemetry/track.ts:L1-L156 — track.ts (imports, depth 2)
  21: import type { AgentHost } from './contract.js';

Test signal per changed area — 1 ✓ · 1 ✗ · 1 –

Reached = a node under a test path has a resolved edge into the changed symbol. It undercounts anything called indirectly — through a CLI, a spawned process or a dynamic import — so read a low ratio as “look here”, never as a coverage gate.

• ✓ Host Setup — 2 of 10 reached · 2 test files changed here: test/hosts-init.test.ts, test/hosts-registry.test.ts
  • not reached: detectPiOmp, wants, installPiOmpGlobal, ompAgentDir, piAgentDir, piExtensionSourcePath, piOmpGlobalPaths, piOmpTargets
• – Telemetry Contract — no function, method or class changed here
• ✗ Extension Grafting — 0 of 7 reached · no test file reaches it
  • not reached: askGraft, formatPack, readIndex, readState, relevantRetrieval, renderStatus, writeState

9 test suites also reference this code

11 symbols, kept out of the diagram and the table so they cannot crowd out the areas a reviewer has to look at.

• test/claude-init.test.ts
• test/cli-picker.test.ts
• test/hosts-antigravity.test.ts
• test/hosts-claude-global.test.ts
• test/hosts-cursor-hooks.test.ts
• test/hosts-plan.test.ts
• test/hosts-retract.test.ts
• test/upkeep-hooks.test.ts
• test/upkeep.test.ts

⚠️ 3 changed files not in the graph (.omp/hooks/pre/graft.ts, .pi/extensions/graft.ts, AGENTS.md) — no parser claims the extension, or the index predates the file.

_{graft blast · origin/main...HEAD · depth 2 · 11 changed files}

Open the interactive graph → — click an area to see its dependent symbols at file:line.

[soydachi]

Pushed an update: the extension now installs both repo-locally and user-level (mirroring how Codex/Claude Code already split it):

• Repo-local: .pi/extensions/graft.ts + .omp/hooks/pre/graft.ts (Cursor posture — --no-global keeps it)
• User-level: `` (else ~/.pi/agent/extensions/ and `~/.omp/agent/hooks/pre/`) (Codex/Claude posture — `--no-global` suppresses it)

The user-level copy governs every project safely because the extension gates on graft/INDEX.md in the project cwd — no graph, no-op. Per-project session state lives under that project's graft/, so sessions never cross. --dry-run reports the global writes as scope 'global' the same way the Claude/Codex ones already are.