[typespec-ts] Sync tsconfig.src include with warp exports for multi-client packages (#4872)

Multi-client packages failed to build with `DIST_MISSING`: the generated
`config/tsconfig.src.*.json` files hardcoded `include:
["../src/index.ts"]`, while `warp.config.yml` exported every client's
entry point as a separate subpath (`./devCenter` →
`./src/devCenter/index.ts`). Since the root `src/index.ts` imports the
deeper client/api files directly instead of re-exporting the per-client
barrels, TypeScript never emitted those barrels to `dist`, and warp's
export validation failed.

### Changes

- **`build-ts-config.ts`**: New `getSrcIncludePaths(exports)` derives
the `include` list from the same `exports` map that drives
`warp.config.yml` — mapping `./src/...` → `../src/...`, dropping
non-`.ts` values (e.g. `package.json`), de-duplicating, and always
keeping `../src/index.ts` as fallback. The four
`buildTsSrc{Esm,Browser,ReactNative,Cjs}Config` builders now take
`exports`.
- **`index.ts`**: Threads `modularPackageInfo.exports` into the
`buildTsSrc*Config` builders in both the initial-generation and
update/migration paths, keeping the tsconfig inputs and warp exports in
sync.
- **Tests**: `test-next/unit/metadata/ts-config.test.ts` covering
default fallback, multi-client sync, non-`.ts` filtering,
de-duplication, and per-target propagation.

For the multi-client example in the issue, the emitted configs now
include every exported barrel:

```jsonc
// config/tsconfig.src.esm.json
"include": [
  "../src/index.ts",
  "../src/devCenter/index.ts",
  "../src/devCenter/api/index.ts",
  "../src/devBoxes/index.ts",
  "../src/deploymentEnvironments/index.ts",
  "../src/models/index.ts"
]
```

---------

Co-authored-by: copilot-swe-agent[bot] <198982749+Copilot@users.noreply.github.com>
Co-authored-by: kazrael2119 <98569699+kazrael2119@users.noreply.github.com>
Co-authored-by: JialinHuang803 <139532647+JialinHuang803@users.noreply.github.com>

Author: 3 people

.chronus/changes/fix-multi-client-tsconfig-src-include-2026-7-13-6-30-0.md

@@ -0,0 +1,7 @@
+---
+changeKind: fix
+packages:
+  - "@azure-tools/typespec-ts"
+---
+
+Fix multi-client package build failures by syncing the generated `config/tsconfig.src.*.json` `include` lists with the `warp.config.yml` exports, so every client entry point is compiled and emitted to `dist` (previously warp failed with `DIST_MISSING`).

packages/typespec-ts/src/index.ts

@@ -461,12 +461,12 @@ export async function $onEmit(context: EmitContext) {
       // Generate warp.config.yml for Azure monorepo ESM packages
       commonBuilders.push((model) => buildWarpConfig(model, modularPackageInfo));
       commonBuilders.push(buildTsConfig);
-      commonBuilders.push(buildTsSrcEsmConfig);
-      commonBuilders.push(buildTsSrcBrowserConfig);
+      commonBuilders.push(() => buildTsSrcEsmConfig(modularPackageInfo["exports"]));
+      commonBuilders.push(() => buildTsSrcBrowserConfig(modularPackageInfo["exports"]));
       if (option.generateReactNativeTarget) {
-        commonBuilders.push(buildTsSrcReactNativeConfig);
+        commonBuilders.push(() => buildTsSrcReactNativeConfig(modularPackageInfo["exports"]));
       }
-      commonBuilders.push(buildTsSrcCjsConfig);
+      commonBuilders.push(() => buildTsSrcCjsConfig(modularPackageInfo["exports"]));
       if (option.generateSample) {
         commonBuilders.push(buildTsSampleConfig);
       }
@@ -531,6 +531,14 @@ export async function $onEmit(context: EmitContext) {
       // Update warp.config.yml for Azure monorepo packages
       updateBuilders.push((model: ClientModel) => buildWarpConfig(model, modularPackageInfo));
 
+      // Re-sync tsconfig.src.*.json `include` with the warp exports
+      updateBuilders.push(() => buildTsSrcEsmConfig(modularPackageInfo["exports"]));
+      updateBuilders.push(() => buildTsSrcBrowserConfig(modularPackageInfo["exports"]));
+      if (option.generateReactNativeTarget) {
+        updateBuilders.push(() => buildTsSrcReactNativeConfig(modularPackageInfo["exports"]));
+      }
+      updateBuilders.push(() => buildTsSrcCjsConfig(modularPackageInfo["exports"]));
+
       // If the client name changed, regenerate the README and snippets completely;
       // otherwise update only the API reference link in-place.
       if (hasReadmeFile) {

packages/typespec-ts/src/metadata/build-ts-config.ts

@@ -52,10 +52,27 @@ export function buildTsConfig(model: ClientModel) {
   };
 }
 
+/**
+ * Derives the tsconfig `include` list from the warp `exports` map so every
+ * exported client entry point is compiled and emitted to `dist`; if they drift
+ * out of sync, warp fails the build with `DIST_MISSING`. Root index is the fallback.
+ */
+export function getSrcIncludePaths(exports?: Record<string, string>): string[] {
+  const includes = new Set<string>(["../src/index.ts"]);
+  if (exports) {
+    for (const value of Object.values(exports)) {
+      if (typeof value === "string" && value.endsWith(".ts")) {
+        includes.add(value.replace(/^\.\//, "../"));
+      }
+    }
+  }
+  return Array.from(includes);
+}
+
 /**
  * Builds config/tsconfig.src.esm.json — extends eng/tsconfigs/src.esm.json
  */
-export function buildTsSrcEsmConfig() {
+export function buildTsSrcEsmConfig(exports?: Record<string, string>) {
   return {
     path: "config/tsconfig.src.esm.json",
     content: JSON.stringify(
@@ -64,7 +81,7 @@ export function buildTsSrcEsmConfig() {
         compilerOptions: {
           resolveJsonModule: true,
         },
-        include: ["../src/index.ts"],
+        include: getSrcIncludePaths(exports),
       },
       null,
       2,
@@ -75,7 +92,7 @@ export function buildTsSrcEsmConfig() {
 /**
  * Builds config/tsconfig.src.browser.json — extends eng/tsconfigs/src.browser.json
  */
-export function buildTsSrcBrowserConfig() {
+export function buildTsSrcBrowserConfig(exports?: Record<string, string>) {
   return {
     path: "config/tsconfig.src.browser.json",
     content: JSON.stringify(
@@ -84,7 +101,7 @@ export function buildTsSrcBrowserConfig() {
         compilerOptions: {
           resolveJsonModule: true,
         },
-        include: ["../src/index.ts"],
+        include: getSrcIncludePaths(exports),
       },
       null,
       2,
@@ -95,7 +112,7 @@ export function buildTsSrcBrowserConfig() {
 /**
  * Builds config/tsconfig.src.react-native.json — extends eng/tsconfigs/src.react-native.json
  */
-export function buildTsSrcReactNativeConfig() {
+export function buildTsSrcReactNativeConfig(exports?: Record<string, string>) {
   return {
     path: "config/tsconfig.src.react-native.json",
     content: JSON.stringify(
@@ -104,7 +121,7 @@ export function buildTsSrcReactNativeConfig() {
         compilerOptions: {
           resolveJsonModule: true,
         },
-        include: ["../src/index.ts"],
+        include: getSrcIncludePaths(exports),
       },
       null,
       2,
@@ -115,7 +132,7 @@ export function buildTsSrcReactNativeConfig() {
 /**
  * Builds config/tsconfig.src.cjs.json — extends eng/tsconfigs/src.cjs.json
  */
-export function buildTsSrcCjsConfig() {
+export function buildTsSrcCjsConfig(exports?: Record<string, string>) {
   return {
     path: "config/tsconfig.src.cjs.json",
     content: JSON.stringify(
@@ -124,7 +141,7 @@ export function buildTsSrcCjsConfig() {
         compilerOptions: {
           resolveJsonModule: true,
         },
-        include: ["../src/index.ts"],
+        include: getSrcIncludePaths(exports),
       },
       null,
       2,

packages/typespec-ts/test-next/unit/metadata/ts-config.test.ts

@@ -0,0 +1,78 @@
+// Copyright (c) Microsoft Corporation.
+// Licensed under the MIT License.
+
+import { describe, expect, it } from "vitest";
+
+import {
+  buildTsSrcBrowserConfig,
+  buildTsSrcCjsConfig,
+  buildTsSrcEsmConfig,
+  buildTsSrcReactNativeConfig,
+  getSrcIncludePaths,
+} from "../../../src/metadata/build-ts-config.js";
+
+describe("tsconfig.src.*.json include generation", () => {
+  it("defaults to the root entry point when no exports are provided", () => {
+    expect(getSrcIncludePaths()).toEqual(["../src/index.ts"]);
+    expect(getSrcIncludePaths({})).toEqual(["../src/index.ts"]);
+  });
+
+  it("keeps the include list in sync with the warp exports for multi-client packages", () => {
+    // Mirrors the exports map produced for a multi-client package.
+    const exports = {
+      ".": "./src/index.ts",
+      "./devCenter": "./src/devCenter/index.ts",
+      "./devCenter/api": "./src/devCenter/api/index.ts",
+      "./devBoxes": "./src/devBoxes/index.ts",
+      "./devBoxes/api": "./src/devBoxes/api/index.ts",
+      "./deploymentEnvironments": "./src/deploymentEnvironments/index.ts",
+      "./deploymentEnvironments/api": "./src/deploymentEnvironments/api/index.ts",
+      "./models": "./src/models/index.ts",
+    };
+
+    const include = getSrcIncludePaths(exports);
+
+    // Every per-client barrel must be a compilation input so it is emitted to dist.
+    expect(include).toContain("../src/index.ts");
+    expect(include).toContain("../src/devCenter/index.ts");
+    expect(include).toContain("../src/devBoxes/index.ts");
+    expect(include).toContain("../src/deploymentEnvironments/index.ts");
+    // The deeper api/model barrels are exported too, so they are included as well.
+    expect(include).toContain("../src/devCenter/api/index.ts");
+    expect(include).toContain("../src/models/index.ts");
+  });
+
+  it("ignores non-TypeScript export values (e.g. package.json)", () => {
+    const include = getSrcIncludePaths({
+      "./package.json": "./package.json",
+      ".": "./src/index.ts",
+    });
+    expect(include).toEqual(["../src/index.ts"]);
+  });
+
+  it("does not emit duplicate include entries", () => {
+    const include = getSrcIncludePaths({
+      ".": "./src/index.ts",
+      "./alias": "./src/index.ts",
+    });
+    expect(include).toEqual(["../src/index.ts"]);
+  });
+
+  it("propagates the exports into each per-target tsconfig", () => {
+    const exports = {
+      ".": "./src/index.ts",
+      "./devCenter": "./src/devCenter/index.ts",
+    };
+
+    for (const build of [
+      buildTsSrcEsmConfig,
+      buildTsSrcBrowserConfig,
+      buildTsSrcReactNativeConfig,
+      buildTsSrcCjsConfig,
+    ]) {
+      const result = build(exports);
+      const parsed = JSON.parse(result.content);
+      expect(parsed.include).toEqual(["../src/index.ts", "../src/devCenter/index.ts"]);
+    }
+  });
+});