Remove implemented todos (#38610)

Went through the todos I had added while implementing the new router and removes everything that is now covered.


## Bug

- [ ] Related issues linked using `fixes #number`
- [ ] Integration tests added
- [ ] Errors have helpful link attached, see `contributing.md`

## Feature

- [ ] Implements an existing feature request or RFC. Make sure the feature request has been accepted for implementation before opening a PR.
- [ ] Related issues linked using `fixes #number`
- [ ] Integration tests added
- [ ] Documentation added
- [ ] Telemetry added. In case of a feature if it's used or not.
- [ ] Errors have helpful link attached, see `contributing.md`

## Documentation / Examples

- [ ] Make sure the linting passes by running `pnpm lint`
- [ ] The examples guidelines are followed from [our contributing doc](https://github.com/vercel/next.js/blob/canary/contributing.md#adding-examples)

packages/next/client/components/reducer.ts

@@ -12,7 +12,6 @@ const fillCacheWithNewSubTreeData = (
   existingCache: CacheNode,
   flightDataPath: FlightDataPath
 ) => {
-  // TODO-APP: handle case of / (root of the tree) refetch
   const isLastEntry = flightDataPath.length <= 4
   const [parallelRouteKey, segment] = flightDataPath
 
@@ -267,7 +266,6 @@ const walkTreeWithFlightDataPath = (
   const [currentSegment, parallelRouteKey] = flightSegmentPath
 
   // Tree path returned from the server should always match up with the current tree in the browser
-  // TODO-APP: verify
   if (!matchSegment(currentSegment, segment)) {
     throw new Error('SEGMENT MISMATCH')
   }
@@ -575,7 +573,6 @@ export function reducer(
 
     cache.data = null
 
-    // TODO-APP: ensure flightDataPath does not have "" as first item
     const flightDataPath = flightData[0]
 
     if (flightDataPath.length !== 2) {

packages/next/server/app-render.tsx

@@ -456,7 +456,7 @@ export async function renderToHTML(
   )
   const isPreview = previewData !== false
   const serverContexts: Array<[string, any]> = [
-    ['WORKAROUND', null], // TODO-APP: First value has a bug currently where the value is not set on the second request
+    ['WORKAROUND', null], // TODO-APP: First value has a bug currently where the value is not set on the second request: https://github.com/facebook/react/issues/24849
     ['HeadersContext', headers],
     ['CookiesContext', cookies],
     ['PreviewDataContext', previewData],
@@ -477,7 +477,6 @@ export async function renderToHTML(
     treeValue: string
     type: DynamicParamTypesShort
   } | null => {
-    // TODO-APP: use correct matching for dynamic routes to get segment param
     const segmentParam = getSegmentParam(segment)
     if (!segmentParam) {
       return null
@@ -643,7 +642,6 @@ export async function renderToHTML(
     let fetcher: (() => Promise<any>) | null = null
 
     type GetServerSidePropsContext = {
-      // TODO-APP: has to be serializable
       headers: IncomingHttpHeaders
       cookies: NextApiRequestCookies
       layoutSegments: FlightSegmentPath
@@ -669,7 +667,7 @@ export async function renderToHTML(
         headers,
         cookies,
         layoutSegments: segmentPath,
-        // TODO-APP: Currently query holds params and pathname is not the actual pathname, it holds the dynamic parameter
+        // TODO-APP: change pathname to actual pathname, it holds the dynamic parameter currently
         ...(isPage ? { query, pathname } : {}),
         ...(pageIsDynamic ? { params: currentParams } : undefined),
         ...(isPreview
@@ -685,7 +683,6 @@ export async function renderToHTML(
     if (layoutOrPageMod.getStaticProps) {
       const getStaticPropsContext = {
         layoutSegments: segmentPath,
-        // TODO-APP: change this to be URLSearchParams instead?
         ...(isPage ? { pathname } : {}),
         ...(pageIsDynamic ? { params: currentParams } : undefined),
         ...(isPreview
@@ -832,9 +829,6 @@ export async function renderToHTML(
   // TODO-APP: validate req.url as it gets passed to render.
   const initialCanonicalUrl = req.url!
 
-  // TODO-APP: change tree to accommodate this
-  // /blog/[...slug]/page.js -> /blog/hello-world/b/c/d -> ['children', 'blog', 'children', ['slug', 'hello-world/b/c/d']]
-  // /blog/[slug] /blog/hello-world -> ['children', 'blog', 'children', ['slug', 'hello-world']]
   const initialTree = createFlightRouterStateFromLoaderTree(tree)
 
   const initialStylesheets: string[] = getCSSInlinedLinkTags(