jac-sv-endpoints

Implement Jac server endpoints using walker and function routes with typed responses.

Updated Jul 26, 2026

Search Tags:#routing #file upload #rest api #endpoints #web server #walker #jac

Ready to run

npx skills add https://github.com/nihalnihalani/jachacks-sf-2026 --skill jac-sv-endpoints-nihalnihalani

💬 Prompt for ChatGPT / Claude Chat▼

Please help me install this Agent Skill.
Skill: jac-sv-endpoints
Source: https://github.com/nihalnihalani/jachacks-sf-2026/tree/main/plugins/jac-codex/skills/jac-sv-endpoints
Command: npx skills add https://github.com/nihalnihalani/jachacks-sf-2026 --skill jac-sv-endpoints-nihalnihalani

SYSTEM DOCUMENTATION & REQUIREMENTS

What problem does it solve? Choosing and implementing the right endpoint shape in a Jac server is error-prone: developers misuse `walker:pub` for simple RPC calls, hit 404/405 errors from missing imports, or return untyped payloads that break clients. This Skill provides the decision rules and code patterns for building correct REST and RPC endpoints in Jac. ## Core Features & Use Cases - Endpoint shape selection: Decide between `def:pub` functions (RPC style, typed returns) and `walker:pub` (REST style, graph traversal) based on whether the endpoint actually walks the graph. - Custom REST routes: Use `@restspec` to define custom HTTP methods, paths, path/query parameters, and file uploads with `UploadFile`. - Response envelopes and pitfalls: Understand the standard `{ok, data, error}` envelope, `_jac_id` volatility, auth visibility rules (`:pub` vs `:priv`), and common failures like stale persisted anchors. - Use Case: You are building a Jac API service consumed over raw REST and need a `GET /users/{user_id}/orders` endpoint with query filters and a typed JSON response. ## Quick Start Ask the agent to add a public Jac endpoint that lists items and a walker endpoint that traverses the graph, following the jac-sv-endpoints patterns.

Frequently Asked Questions about jac-sv-endpoints

High-intent search queries and answers about installing and using this skill.

FAQPage Schema

How do I create a REST endpoint in Jac?▼

Define a `walker:pub` with `has` fields as the request body and use `report` for the response, or define a `def:pub` function whose typed return value becomes the wire format. Call walkers at `POST /walker/<name>` and functions at `POST /function/<name>`.

When should I use walker:pub versus def:pub in Jac?▼

Use `def:pub` when the endpoint does not traverse the graph: status probes, single-node CRUD, list queries, and job kick-offs. Reserve `walker:pub` for endpoints that spawn, visit edges, accumulate results, and report once.

How do I add custom routes and GET methods to Jac endpoints?▼

Apply `@restspec(method=HTTPMethod.GET, path="/users/{user_id}/orders")` to a walker or function. Parameters matching `{...}` in the path become path parameters, `UploadFile` fields become file uploads, and remaining fields become query or body parameters.

Why does my new Jac endpoint return 404 or 405?▼

The endpoint name is missing from the entry module's import list. Adding a `def:pub` to an already-imported module still fails until the new name is explicitly imported in the entry module.

How do I handle file uploads in a Jac server endpoint?▼

Import `UploadFile` from `http`, declare a `has file: UploadFile` field on the walker, and it is classified as a multipart file parameter. Use the ambient `store()` builtin to save the file to local disk or S3 backends.

Why do Jac responses contain changing _jac_id values?▼

The runtime assigns a fresh `_jac_id` to the walker instance and every freshly-constructed report object on each response, while persistent node jids stay stable. Strip `_jac_id` before hashing, caching, or diffing responses.