Add Copilot instructions for repository

.github/copilot-instructions.md

@@ -0,0 +1,118 @@
+# AEP OpenAPI Linter - Copilot Instructions
+
+## Project Overview
+
+This is a Spectral ruleset for linting OpenAPI documents to ensure compliance
+with [API Enhancement Proposals (AEPs)](https://aep.dev). The linter checks
+OpenAPI definitions against AEP standards for API design.
+
+## Build, Test, and Lint Commands
+
+```bash
+# Install dependencies
+npm install
+
+# Run tests (full suite with coverage)
+npm test
+
+# Run a single test file
+npx jest test/parameter-names-unique.test.js
+
+# Run tests for a specific AEP
+npx jest test/0131
+
+# Run linter (Prettier + ESLint)
+npm run lint
+
+# Auto-fix linting issues
+npm run lint-fix
+```
+
+## Architecture
+
+### Structure
+
+- **`spectral.yaml`** - Main ruleset that extends individual AEP rulesets and
+  defines cross-cutting rules
+- **`aep/*.yaml`** - Individual ruleset files, one per AEP number (e.g.,
+  `0131.yaml` for AEP-131)
+- **`functions/*.js`** - Custom Spectral functions for complex validation logic
+  that cannot be expressed with built-in Spectral functions
+- **`test/`** - Test files organized by rule or AEP number
+
+**Note**: Custom functions should only be used when it is difficult or
+impossible to express the rule with built-in Spectral functions (e.g.,
+`schema`, `pattern`, `truthy`, `falsy`, `length`, etc.).
+
+### Rule Organization
+
+Each AEP ruleset file (`aep/XXXX.yaml`) contains:
+
+- **Aliases** - Reusable JSONPath patterns (e.g., `GetOperation`,
+  `ListOperation`)
+- **Functions** - Custom functions specific to that AEP (if needed)
+- **Rules** - Individual validation rules with format
+  `aep-{number}-{description}` listed alphabetically by rule name
+
+### Test Organization
+
+Tests are organized in two ways:
+
+1. **By rule name** - `test/{rule-name}.test.js` for cross-cutting rules
+2. **By AEP number** - `test/{aep-number}/{rule-aspect}.test.js` for
+   AEP-specific rules
+
+Each test uses the `linterForRule` utility to test specific rules in isolation.
+
+## Key Conventions
+
+### Rule Naming and Severity
+
+- Rules MUST be prefixed with `aep-` and listed alphabetically in
+  `spectral.yaml`
+- Custom function names MUST match the rule name minus the `aep-` prefix
+- Functions declared in a file's `functions:` list MUST be used by at least one
+  rule in that same file (no unused function declarations)
+- Rule severity mapping:
+  - `error` - for AEP or OpenAPI **MUST** guidelines
+  - `warn` - for AEP or OpenAPI **SHOULD** guidelines
+  - `info` - for other helpful checks
+  - Never use `hint` - not supported by VSCode extension
+
+### Adding New Rules
+
+When adding a new rule, create/update these four locations:
+
+1. **Rule definition** - In `spectral.yaml` or appropriate `aep/XXXX.yaml` file
+2. **Custom function** (if needed) - In `functions/{rule-name}.js`
+3. **Tests** - In `test/{rule-name}.test.js` or
+   `test/{aep-number}/{aspect}.test.js`
+4. **Documentation** - In `docs/XXXX.md` (for AEP-specific rules) or
+   `docs/rules.md` (for general rules)
+
+### Testing Requirements
+
+- Test at minimum: error case and no-error case for each rule
+- Code coverage MUST be > 80% for all functions in `functions/*.js`
+- Use the `linterForRule()` utility from `test/utils.js` to test rules in
+  isolation
+- Use custom matchers from `test/matchers.js` (e.g., `.toContainMatch()`)
+
+### Example File Sync
+
+The `examples/example.oas.yaml` file is sourced from the upstream
+[aep.dev repository](https://github.com/aep-dev/aeps) at
+`aep/general/example.oas.yaml`. Do NOT modify it directly here. If the linter
+detects issues:
+
+1. Verify the issue is a true positive
+2. Fix it upstream in the aep.dev repository
+3. Copy the corrected version back to this repo
+
+This keeps the example file synchronized with the canonical AEP documentation.
+
+## Code Style
+
+Follow the
+[Google JavaScript Style Guide](https://google.github.io/styleguide/jsguide.html)
+for functions and tests.

spectral.yaml

@@ -18,10 +18,7 @@ extends:
   - ./aep/0193.yaml
 functionsDir: './functions'
 functions:
-  - aep-142-time-field-type
   - parameter-names-unique
-  - operations-endpoint
-  - standardized-codes
 rules:
   openapi-tags: off
   operation-tags: off