feat(examples): add examples.yaml JSON schema and examples-validate tool

Add @azure-tools/typespec-azure-examples, the foundational piece of the
Unified Examples Format epic (#4831, issue #4832):

- examples.yaml JSON Schema authored in TypeSpec (schema/examples-yaml.tsp)
  and compiled via @typespec/json-schema.
- examples-validate CLI + programmatic API that runs structural (ajv)
  validation plus the RFC section 3 semantic rules: metadata keys,
  integer-only status codes, quoted since in service.yaml, per-lineage
  base/uniqueness, one-interface-per-file, and {api-version}-only placeholder.

Author: timotheeguerin

.chronus/changes/add-examples-validate-tool-2026-07-15-12-30-00.md

@@ -0,0 +1,7 @@
+---
+changeKind: feature
+packages:
+  - "@azure-tools/typespec-azure-examples"
+---
+
+Add `@azure-tools/typespec-azure-examples` with the `examples.yaml` JSON Schema and the `examples-validate` tool for the unified examples format.

packages/typespec-azure-examples/.gitignore

@@ -0,0 +1,3 @@
+dist/
+temp/
+schema/dist/

packages/typespec-azure-examples/.scripts/schema-json-to-js.js

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+// @ts-check
+
+import { readFile, writeFile } from "fs/promises";
+import { dirname, resolve } from "path";
+import { fileURLToPath } from "url";
+
+const __dirname = dirname(fileURLToPath(import.meta.url));
+
+const jsonFilename = resolve(__dirname, "../schema/dist/ExamplesYaml.json");
+const jsFilename = resolve(__dirname, "../schema/dist/schema.js");
+console.log("Reading json schema at:", jsonFilename);
+const content = await readFile(jsonFilename);
+
+const json = JSON.parse(content.toString());
+
+const jsContent = `
+const schema = ${JSON.stringify(json)};
+export default schema;
+`;
+console.log("Writing json schema in js file:", jsFilename);
+await writeFile(jsFilename, jsContent);

packages/typespec-azure-examples/README.md

@@ -0,0 +1,83 @@
+# @azure-tools/typespec-azure-examples
+
+Tooling for the Azure **unified examples format** (`examples.yaml`): the published JSON Schema
+and the `examples-validate` CLI.
+
+The unified examples format replaces the ~282K per-version `x-ms-examples` JSON files with a
+single version-aware `examples.yaml` per service (or `examples/<Interface>.yaml` for large
+services). See the RFC: _Unified Examples Format_.
+
+## Format
+
+```yaml
+$schema: https://raw.githubusercontent.com/Azure/azure-rest-api-specs/main/schemas/examples.schema.yaml
+$namespace: Microsoft.EventGrid
+
+CaCertificates.get:
+  - request:
+      path:
+        subscriptionId: 8f6b6269-84f2-4d09-9e31-1127efcd1e40
+        resourceGroupName: myResourceGroup
+    responses:
+      200:
+        body:
+          name: exampleCaCertificate
+          properties:
+            provisioningState: Succeeded
+  - since: "2023-12-15-preview"
+    request:
+      path:
+        subscriptionId: 8f6b6269-84f2-4d09-9e31-1127efcd1e40
+        resourceGroupName: myResourceGroup
+    responses:
+      200:
+        body:
+          name: exampleCaCertificate
+          properties:
+            provisioningState: Succeeded
+            delegatedIdentityTokenExpirationTimeInUtc: "2023-10-12T23:06:43+00:00"
+```
+
+- File metadata uses `$`-prefixed keys (`$schema`, `$namespace`); every bare top-level key is an
+  operation, identified by its interface-relative name (`Interface.operation`).
+- Each operation maps to a list of example variants. The base variant has no `since`; later
+  variants carry a quoted `since` and restate the full request/response.
+- Response status codes are bare integer keys. `api-version` is implicit; use the
+  `{api-version}` placeholder where a version must be embedded in a value.
+
+## `examples-validate`
+
+Validate a service's example files against the JSON Schema and the format rules:
+
+```bash
+examples-validate <service-dir>
+```
+
+It discovers `examples.yaml` and `examples/*.yaml` in the directory, reads the adjacent
+`service.yaml` for version metadata, and reports diagnostics. It exits non-zero if any error is
+found (use `--warn-as-error` to also fail on warnings).
+
+### Rules enforced
+
+- Only `$schema`/`$namespace` may be `$`-prefixed; other bare keys are operations that must be a
+  list of examples.
+- Response keys are integer status codes; range keys (`2XX`) and `default` are rejected.
+- `since` must be a quoted string and a version listed in `service.yaml`.
+- Per lineage (entries grouped by `title`; untitled entries form the default lineage): at most one
+  entry without `since`, and `since` values are unique.
+- An operation's full example set lives in a single file, and each interface appears in exactly
+  one file.
+- `{api-version}` is the only supported placeholder, and `api-version` must not appear as a
+  request parameter.
+
+## API
+
+```ts
+import {
+  validateExamplesDir,
+  validateExampleFiles,
+  loadExampleFile,
+} from "@azure-tools/typespec-azure-examples";
+
+const { diagnostics } = await validateExamplesDir("path/to/service");
+```

packages/typespec-azure-examples/package.json

@@ -0,0 +1,68 @@
+{
+  "name": "@azure-tools/typespec-azure-examples",
+  "version": "0.1.0",
+  "author": "Microsoft Corporation",
+  "description": "Tooling for the Azure unified examples format (examples.yaml): JSON Schema and the examples-validate CLI",
+  "homepage": "https://azure.github.io/typespec-azure",
+  "readme": "https://github.com/Azure/typespec-azure/blob/main/README.md",
+  "license": "MIT",
+  "repository": {
+    "type": "git",
+    "url": "git+https://github.com/Azure/typespec-azure.git"
+  },
+  "bugs": {
+    "url": "https://github.com/Azure/typespec-azure/issues"
+  },
+  "keywords": [
+    "typespec",
+    "azure",
+    "examples"
+  ],
+  "type": "module",
+  "main": "dist/src/index.js",
+  "exports": {
+    ".": {
+      "types": "./dist/src/index.d.ts",
+      "default": "./dist/src/index.js"
+    }
+  },
+  "bin": {
+    "examples-validate": "./dist/src/cli.js"
+  },
+  "engines": {
+    "node": ">=22.0.0"
+  },
+  "scripts": {
+    "clean": "rimraf ./dist ./schema/dist",
+    "build": "npm run regen-examples-yaml-schema && tsc -p tsconfig.build.json",
+    "watch": "tsc -p tsconfig.build.json --watch",
+    "regen-examples-yaml-schema": "tsp compile ./schema/examples-yaml.tsp --warn-as-error && node ./.scripts/schema-json-to-js.js",
+    "test": "vitest run",
+    "test:watch": "vitest -w",
+    "test:ci": "vitest run --coverage --reporter=junit --reporter=default",
+    "lint": "oxlint . --deny-warnings",
+    "lint:fix": "oxlint . --fix"
+  },
+  "files": [
+    "schema/dist/schema.js",
+    "schema/dist/ExamplesYaml.json",
+    "dist/**",
+    "!dist/test/**"
+  ],
+  "dependencies": {
+    "ajv": "catalog:",
+    "picocolors": "catalog:",
+    "yaml": "catalog:",
+    "yargs": "catalog:"
+  },
+  "devDependencies": {
+    "@types/node": "catalog:",
+    "@types/yargs": "catalog:",
+    "@typespec/compiler": "workspace:^",
+    "@typespec/json-schema": "workspace:^",
+    "@vitest/coverage-v8": "catalog:",
+    "rimraf": "catalog:",
+    "typescript": "catalog:",
+    "vitest": "catalog:"
+  }
+}

packages/typespec-azure-examples/schema/.gitignore

@@ -0,0 +1 @@
+dist/

packages/typespec-azure-examples/schema/examples-yaml.tsp

@@ -0,0 +1,87 @@
+/**
+ * Source of truth for the `examples.yaml` unified examples format emitted/consumed by
+ * Azure tooling. The JSON Schema generated from this file is published for editor and CI
+ * validation and is used by the `examples-validate` tool (via ajv).
+ *
+ * See the RFC: Unified Examples Format (§3–§4).
+ *
+ * Note: because YAML permits arbitrary string keys, status codes, headers, query params, and
+ * map-shaped bodies are modeled as `Record<...>`. Rules that JSON Schema cannot express
+ * (integer-only status codes, quoted `since`, `since` ∈ `service.yaml`, per-lineage
+ * uniqueness, file placement, `{api-version}`-only placeholder) are enforced by the
+ * `examples-validate` semantic rules.
+ */
+import "@typespec/json-schema";
+
+using JsonSchema;
+
+/**
+ * Top-level `examples.yaml` file: `$schema`/`$namespace` metadata plus one entry per
+ * operation, keyed by the interface-relative operation name (e.g. `CaCertificates.get`).
+ * Each operation maps to a list of example variants.
+ *
+ * The indexer is widened to `Example[] | string` so the `$`-prefixed string metadata keys
+ * are structurally valid. The rules that a bare (non-`$`) key must be a list of examples and
+ * that the only allowed metadata keys are `$schema`/`$namespace` are enforced by the
+ * `examples-validate` semantic rules.
+ */
+@jsonSchema("examples.yaml")
+model ExamplesYaml is Record<Example[] | string> {
+  /** Schema URL. Gives editors autocomplete and inline validation while authoring. */
+  $schema?: string;
+
+  /**
+   * Service namespace (e.g. `Microsoft.EventGrid`), prepended to each operation key to form
+   * the fully-qualified operation identity used for Swagger linkage (`x-id`).
+   */
+  $namespace?: string;
+}
+
+/** A single example variant representing one complete API interaction. */
+model Example {
+  /**
+   * Optional human-readable title. Omit for the single-example case; provide it only to
+   * disambiguate multiple distinct examples on the same operation. Entries sharing a `title`
+   * form one lineage; untitled entries all belong to the single default lineage.
+   */
+  title?: string;
+
+  /** Longer description of what this example demonstrates. */
+  description?: string;
+
+  /**
+   * Quoted version from which this variant applies (must be a version listed in the service's
+   * `service.yaml`). Omit to apply from the earliest version.
+   */
+  since?: string;
+
+  /** The request of the API interaction. */
+  request: ExampleRequest;
+
+  /** Responses keyed by integer status code (e.g. `200`, `404`). */
+  responses: Record<ExampleResponse>;
+}
+
+/** The request portion of an example, split by parameter location. */
+model ExampleRequest {
+  /** Path parameters. `api-version` is implicit and MUST NOT be included. */
+  path?: Record<unknown>;
+
+  /** Query parameters (e.g. `$top`, `$filter`). */
+  query?: Record<unknown>;
+
+  /** Request headers (e.g. `If-Match`). */
+  headers?: Record<unknown>;
+
+  /** Request body. Structure matches the operation's request schema. */
+  body?: unknown;
+}
+
+/** A single response of an example, keyed in the parent map by integer status code. */
+model ExampleResponse {
+  /** Response headers (e.g. `Location`, `Azure-AsyncOperation`). */
+  headers?: Record<unknown>;
+
+  /** Response body. Structure matches the operation's response schema. */
+  body?: unknown;
+}

packages/typespec-azure-examples/schema/tspconfig.yaml

@@ -0,0 +1,7 @@
+emit:
+  - "@typespec/json-schema"
+
+options:
+  "@typespec/json-schema":
+    emitter-output-dir: "{project-root}/dist"
+    file-type: json

packages/typespec-azure-examples/src/cli.ts

@@ -0,0 +1,51 @@
+#!/usr/bin/env node
+/* eslint-disable no-console */
+import { resolve } from "path";
+import yargs from "yargs";
+import { hideBin } from "yargs/helpers";
+import { validateExamplesDir } from "./discover.js";
+import { formatDiagnostics, formatSummary } from "./reporter.js";
+
+async function main(): Promise<void> {
+  const args = await yargs(hideBin(process.argv))
+    .scriptName("examples-validate")
+    .usage("$0 [dir]", "Validate unified examples format files (examples.yaml)")
+    .positional("dir", {
+      type: "string",
+      describe: "Service directory containing examples.yaml / examples/*.yaml and service.yaml",
+      default: ".",
+    })
+    .option("warn-as-error", {
+      type: "boolean",
+      default: false,
+      describe: "Treat warnings as errors (non-zero exit)",
+    })
+    .strict()
+    .help()
+    .parse();
+
+  const dir = resolve(process.cwd(), args.dir as string);
+  const { diagnostics, files } = await validateExamplesDir(dir);
+
+  if (files.length === 0) {
+    console.error(
+      `No examples files found in ${dir} (looked for examples.yaml and examples/*.yaml).`,
+    );
+    process.exit(1);
+  }
+
+  if (diagnostics.length > 0) {
+    console.log(formatDiagnostics(diagnostics));
+    console.log("");
+  }
+  console.log(formatSummary(diagnostics));
+
+  const hasError = diagnostics.some((d) => d.severity === "error");
+  const hasWarning = diagnostics.some((d) => d.severity === "warning");
+  process.exit(hasError || (args["warn-as-error"] && hasWarning) ? 1 : 0);
+}
+
+main().catch((error) => {
+  console.error(error);
+  process.exit(1);
+});