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 skills add mpsuesser/pi-effect-harness --skill effect-schema-v4git 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/skills/mpsuesser/pi-effect-harness/effect-schema-v4)<a href="https://agentmods.dev/skills/mpsuesser/pi-effect-harness/effect-schema-v4"><img src="https://agentmods.dev/badge/skills/mpsuesser/pi-effect-harness/effect-schema-v4/github.svg" alt="Measured on agentmods" height="20"></a>Or the 80×15 button, for a site that already has a row of RSS and ATOM ones. Only the verdict fits; the numbers stay here.
<a href="https://agentmods.dev/skills/mpsuesser/pi-effect-harness/effect-schema-v4"><img src="https://agentmods.dev/badge/skills/mpsuesser/pi-effect-harness/effect-schema-v4.svg" alt="Reviewed on agentmods" width="80" 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 5.1 | $0.00052 | $0.05281 |
| Opus 5 | $0.00026 | $0.02641 |
| Sonnet 5 | $0.00010 | $0.01056 |
| Haiku 4.5 | $0.00005 | $0.00528 |
Grade A, and why
effect-schema-v4 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 9d 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 — 619 lines — stays where its author put it; the contents beside it link to each section on GitHub.
You are an Effect TypeScript expert. This skill is a migration reference — it documents the key v4 Schema API changes so you don't accidentally use v3 patterns.
Effect Source Reference
The Effect v4 source is available at ~/.cache/effect-v4/.
Browse and read files there directly to look up APIs, types, and implementations.
Reference this for:
- Full Schema API:
packages/effect/SCHEMA.md - Migration guide:
migration/schema.md - SchemaTransformation module:
packages/effect/src/SchemaTransformation.ts - SchemaGetter module:
packages/effect/src/SchemaGetter.ts
1. Key Renames (find-and-replace safe)
| v3 | v4 | Notes |
|---|---|---|
annotations(ann) |
annotate(ann) |
|
compose(schemaB) |
decodeTo(schemaB) or decodeTo(schemaB, transformation) |
Transformation is optional; omitted uses passthrough composition |
typeSchema(schema) |
toType(schema) |
|
asSchema(schema) |
revealCodec(schema) |
|
equivalence() |
toEquivalence() |
|
arbitrary() |
toArbitrary() |
|
pretty() |
toFormatter() |
|
parseJson() |
UnknownFromJsonString |
No-arg version is now a standalone schema |
parseJson(schema) |
fromJsonString(schema) |
With-schema version |
TaggedError |
TaggedErrorClass |
Class name change |
BigIntFromSelf |
BigInt |
|
SymbolFromSelf |
Symbol |
|
URLFromSelf |
URL |
|
DateFromSelf |
Date |
All *FromSelf drop the suffix |
DurationFromSelf |
Duration |
|
OptionFromSelf |
Option |
|
EitherFromSelf |
Result |
Also renamed from Either to Result |
RedactedFromSelf |
Redacted |
Expects Redacted values; JSON encoding is allowed by default |
Redacted |
RedactedFromValue |
Raw value → Redacted; encoding is allowed by default |
ChunkFromSelf |
Chunk |
*FromSelf suffix removed |
ReadonlyMapFromSelf |
ReadonlyMap |
*FromSelf suffix removed |
ReadonlySetFromSelf |
ReadonlySet |
*FromSelf suffix removed |
HashMapFromSelf |
HashMap |
*FromSelf suffix removed |
HashSetFromSelf |
HashSet |
*FromSelf suffix removed |
BigDecimalFromSelf |
BigDecimal |
*FromSelf suffix removed |
CauseFromSelf |
Cause |
*FromSelf suffix removed |
ExitFromSelf |
Exit |
*FromSelf suffix removed |
RegExpFromSelf |
RegExp |
*FromSelf suffix removed |
encodedSchema(schema) |
toEncoded(schema) |
|
decodingFallback annotation |
catchDecoding(...) |
Annotation replaced by combinator |
Literal(null) |
Null |
Standalone schema for null |
standardSchemaV1 |
toStandardSchemaV1 |
|
nonEmptyString |
isNonEmpty() |
Now used with .check() |
disableValidation |
disableChecks |
In MakeOptions for Class constructors |
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.
- 9d ago First seen · 619 lines · 52 tokens per session scan A 9536b718fa94
effect-schema-v4 is a skill published in the GitHub repository mpsuesser/pi-effect-harness (24 stars, last pushed 2mo ago), licensed MIT. It adds 52 tokens to every session and 5,281 once invoked, about $0.0003 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.
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