fix(web-app): defer to a user-configured client-hmr row

The whole-tree name scan (entries() recurses into subtrees) already
skips creation when any patch layer carries the row, including a
disabled one; make that contract explicit in the comment, pin it with a
test, and record it in the Agent Note.

packages/bundle/web-app/src/index.ts

@@ -160,8 +160,11 @@ export function apply(ctx: Context, config: Config): void {
     } else {
       void loader.await().then(async () => {
         // The tree can be disposed while settlement was in flight (early
-        // SIGTERM); re-check before mutating it. A reload of this fiber must
-        // not duplicate the row a previous generation created.
+        // SIGTERM); re-check before mutating it. The name scan spans every
+        // tree (entries() recurses into subtrees), so a row the user
+        // configured in a patch layer — enabled, reconfigured, or
+        // deliberately disabled — wins over this default, and a reload of
+        // this fiber never duplicates the row a previous generation created.
         if (ctx.get('loader') === undefined) return
         const mounted = [...ctx.loader.entries()].some(entry => entry.options.name === HMR_ROW_NAME)
         if (!mounted) await ctx.loader.create({ name: HMR_ROW_NAME })

packages/bundle/web-app/tests/web-app.spec.ts

@@ -187,6 +187,28 @@ describe('web-app runtime glue', () => {
     await ctx.fiber.dispose()
   })
 
+  it('defers to a user-configured client-hmr row anywhere in the tree', async () => {
+    stageDist()
+    const ctx = new Context()
+    ctx.provide('httpServer', fakeHttpServer().server)
+    const created: string[] = []
+    // The user's own row — possibly patched into an include subtree and even
+    // disabled there — already carries the name; the runtime must not create
+    // a second one beside it.
+    ctx.provide('loader', {
+      entries: () => [{ options: { id: 'my-hmr', name: '@deepseek-ai/dsh-client-hmr', disabled: true } }][Symbol.iterator](),
+      create: (options: { name: string }) => {
+        created.push(options.name)
+        return Promise.resolve(options.name)
+      },
+      await: () => Promise.resolve(),
+    } as never)
+    apply(ctx, new Config({ mode: 'development', printUrl: false, surfaceContext: false, trustedHosts: [] }))
+    await new Promise(resolve => setTimeout(resolve, 0))
+    expect(created).toEqual([])
+    await ctx.fiber.dispose()
+  })
+
   it('skips the dev row when the tree is disposed during settlement and logs a creation failure', async () => {
     stageDist()
     const raced = new Context()