Guideline resolution

Guideline, standard, and policy files each declare the path patterns they govern — a general UI guideline for **/*.{vue,html,jsx}, a Vue-specific one for **/*.vue, an API guideline for src/api/**. Before an agent acts, it needs the subset of those artifacts that apply to where it is about to work ([[DR-0014]]). The applicable set is computed from patterns alone, so the target files need not exist yet.

index builds a reverse index over labeled pattern-sets. It is pure — no filesystem — and compiles each entry once, up front.

index, applicableTo, matching

import { index } from "@sksizer/intersect";

const guidelines = index([
  { id: "guidelines/UI",     patterns: ["**/*.{vue,html,jsx}"] },
  { id: "guidelines/UI/vue", patterns: ["**/*.vue"] },
  { id: "guidelines/api",    patterns: ["src/api/**"] },
]);

// A subtree query (no files need exist), then a concrete-file query:
guidelines.applicableTo("src/siteA/components/**");
guidelines.matching("src/siteA/components/Button.vue");

Call	Returns	Why
applicableTo("src/siteA/components/**")	["guidelines/UI", "guidelines/UI/vue"]	the api guideline doesn’t overlap
matching("src/siteA/components/Button.vue")	["guidelines/UI", "guidelines/UI/vue"]	both UI sets match the file

Query	Scope	Returns
applicableTo(scope)	a pattern-set (a subtree is dir/**)	ids whose set OVERLAPS the scope
matching(path)	a concrete path	ids whose set matches that path

Both return ids in registration order.

Registration order is a prioritization

index keeps the order entries were supplied and both queries return matches in it. Register general-to-specific and read the result as a prioritization — first is most general, last is most specific. Intersect returns the order; the caller picks the precedence rule.

import { index } from "@sksizer/intersect";

// Registration order IS the priority: general first, specific last.
const guidelines = index([
  { id: "guidelines/UI",     patterns: ["**/*.{vue,html,jsx}"] },
  { id: "guidelines/UI/vue", patterns: ["**/*.vue"] },
]);

// applicable is ["guidelines/UI", "guidelines/UI/vue"], in registration order.
const applicable   = guidelines.applicableTo("src/siteA/components/**");
const inOrder      = applicable;        // apply general → specific
const mostSpecific = applicable.at(-1); // "guidelines/UI/vue"

Duplicate ids throw

A guideline “appears twice” only if the caller registers the same id twice. index rejects that at construction rather than silently keeping first or last.

import { index } from "@sksizer/intersect";

index([
  { id: "guidelines/UI", patterns: ["**/*.vue"] },
  { id: "guidelines/UI", patterns: ["**/*.html"] }, // same id, registered twice
]);

Throws Error: duplicate registry id 'guidelines/UI'.

SDLC tie-in

An SDLC standard entity already carries applies_to.paths, so it is a ready-made labeled pattern-set. Feed each standard in, ordered broad → specific, then ask which apply.

import { index } from "@sksizer/intersect";
import { loadStandards, readBody } from "./sdlc";

const standards = index(
  loadStandards().map((s) => ({ id: s.id, patterns: s.applies_to.paths })),
);

// About to work under a directory — which standards apply, in priority order?
const applies = standards.applicableTo("src/siteA/components/**");

// Assemble their guidance as the agent action's context:
const context = applies.map(readBody);

applies is e.g. ["S-0006-skill-md-is-direct-instruction", "S-0012-vue-components"], in priority order; context is their bodies, ready to hand to the agent action.