Getting it into your agent
One page per mod, every tool's command on it. A separate URL per tool would split the same page into five that compete with each other.
npx agentmods add instructions/mpsuesser/pi-effect-harness/agents-mdgit clone --depth 1 https://github.com/mpsuesser/pi-effect-harnessWrote this? Show the measurements
A badge with what this costs and how it scanned, read live from this page, so it follows the numbers instead of freezing them. Markdown for a README, HTML for a documentation site or a project page.
[](https://agentmods.dev/instructions/mpsuesser/pi-effect-harness/agents-md)<a href="https://agentmods.dev/instructions/mpsuesser/pi-effect-harness/agents-md"><img src="https://agentmods.dev/badge/instructions/mpsuesser/pi-effect-harness/agents-md.svg" alt="Measured on agentmods" height="20"></a>What it costs to keep this loaded
Counted locally with the o200k_base tokenizer, which is exact for GPT models; Claude uses its own tokenizer and its counts differ. Treat this as one consistent yardstick across the catalogue rather than a bill. Prices are per million input tokens.
| Model | Per session | Once invoked |
|---|---|---|
| Fable 5 | $0.01252 | $0.01252 |
| Opus 5 | $0.00626 | $0.00626 |
| Sonnet 5 | $0.00250 | $0.00250 |
| Haiku 4.5 | $0.00125 | $0.00125 |
Grade A, and why
pi-effect-harness AGENTS.md scanned grade A with 0 findings against 26 rules in 11 categories — prompt injection, anti-refusal, data exfiltration, privilege escalation, supply chain, agent snooping, system-prompt leakage, SSRF and excessive agency — measured 5d ago.
A static scan of the body, not an audit. Every finding is printed with the line that produced it so you can judge whether it matters here. A mod is markdown that instructs an agent; that is exactly why what it instructs is worth reading.
Nothing flagged
None of the 26 patterns this scan looks for appear in this file: no shell pipes, no recursive deletes, no credential paths, no hidden text, no instruction-override or anti-refusal phrasing, no agent-config snooping. That is not a guarantee, it is the absence of the things that are checkable.
How it starts
The opening of the file, as written. The whole thing — 91 lines — stays where its author put it; the contents beside it link to each section on GitHub.
AGENTS.md — pi-effect-harness
A bun workspace that publishes pi-effect-harness: a Pi extension turning the Pi coding agent into an Effect v4–aware harness. See README.md for the user-facing description.
Layout
packages/
harness-kit/ Internal kernel — Effect services for rules, hooks,
decisions, write projection, pattern matching.
Wraps Pi's ExtensionAPI in an Effect runtime.
agentsmd-undriftable/ CLI (`amdu`) for keeping AGENTS.md sections
deterministically generated from TypeScript source
via ts-morph. Independent utility, lives here for now.
harnesses/
effect/ The published artifact (`pi-effect-harness`).
src/ Extension entrypoint, services, rules, hooks, atoms.
patterns/ 46 ast-grep / regex pattern detectors (md + YAML).
skills/ 41 effect-* skills loaded into Pi's /skill: namespace.
guidance/ Markdown docs merged into the system-prompt header.
test/ One file per source module + a few cross-cutting
tests (all-patterns-covered, skill-gate-projection,
guidance-docs-injection, comment-string-false-positives).
sandboxes/
amdu-demo/ Throwaway projects for trying things out.
Treat as ephemeral.
The split between harness-kit and harnesses/effect is not load-bearing. Code migrates between the two as the kernel firms up. If something feels miscategorized, it probably is — move it.
Verification
bun run check # dprint format + oxlint + tsgo typecheck
bun run test # vitest run
bun run check && bun run test # what CI runs
Single tests:
bunx vitest run harnesses/effect/test/avoid-any.test.ts
bunx vitest run -t "blocks Effect writes"
bun install runs effect-tsgo patch in prepare to patch tsgo for Effect's type-level encoding. Expected; not a problem.
What this file has done since we first saw it
Hashed on every crawl. A supply-chain change to an agent config is a question of when, not whether, so the history is kept rather than the latest state alone.
- 5d ago First seen · 91 lines · 1,252 tokens per session scan A 4c4751d7e990
pi-effect-harness AGENTS.md is an instructions file published in the GitHub repository mpsuesser/pi-effect-harness (24 stars, last pushed 2mo ago), licensed MIT. It adds 1,252 tokens to every session, about $0.0063 per session on Opus 5. A static security scan graded it A with 0 findings. No closer match exists in the catalogue, so it is treated as the original; first seen 2026-08-30.
Other instructions, from other repositories
tether-ai AGENTS.md
AGENTS.md instructions for tt-11-dd/tether-ai, covering tether, 地图, agent skills, 约定 and 检查.
EffectPatterns copilot-instructions.md
Copilot instructions for PaulJPhilp/EffectPatterns, covering effect-patterns ai agent instructions, project overview, key architectural patterns, service pattern and dependency injection.
EffectPatterns GEMINI.md
Gemini CLI instructions for PaulJPhilp/EffectPatterns, covering gemini integration, ai model support, quick start, supported models and features.
EffectPatterns AGENTS.md
AGENTS.md instructions for PaulJPhilp/EffectPatterns: For architecture, agents, integration, config, testing, deployment, security, monitoring, and development guidelines, use.
EffectPatterns CLAUDE.md
Claude Code instructions for PaulJPhilp/EffectPatterns: For architecture (workspace layout, MCP server, database, config, commands, debugging, important files), use.
pi AGENTS.md
AGENTS.md instructions for counterposition/pi, covering agents.md, commands, pattern: pnpm --filter @counterposition/pi-web-search run, single test file and single test by name.