Updates for v7_fetcherPersist post-processing logic (#10977)

Author: brophdawg11

.changeset/fetcher-cleanup.md

@@ -2,10 +2,9 @@
 "@remix-run/router": minor
 ---
 
-Add a new `future.v7_fetcherPersist` flag to the `@remix-run/router` to change the persistence behavior of fetchers when `router.deleteFetcher` is called. Instead of being immediately cleaned up, fetchers will persist until they return to an `idle` state([RFC](https://github.com/remix-run/remix/discussions/7698))
+Add a new `future.v7_fetcherPersist` flag to the `@remix-run/router` to change the persistence behavior of fetchers when `router.deleteFetcher` is called. Instead of being immediately cleaned up, fetchers will persist until they return to an `idle` state ([RFC](https://github.com/remix-run/remix/discussions/7698))
 
 - This is sort of a long-standing bug fix as the `useFetchers()` API was always supposed to only reflect **in-flight** fetcher information for pending/optimistic UI -- it was not intended to reflect fetcher data or hang onto fetchers after they returned to an `idle` state
-- With `v7_fetcherPersist`, the `router` only knows about in-flight fetchers - they do not exist in `state.fetchers` until a `fetch()` call is made, and they are removed as soon as it returns to `idle` (and the data is handed off to the React layer)
 - Keep an eye out for the following specific behavioral changes when opting into this flag and check your app for compatibility:
   - Fetchers that complete _while still mounted_ will no longer appear in `useFetchers()`. They served effectively no purpose in there since you can access the data via `useFetcher().data`).
   - Fetchers that previously unmounted _while in-flight_ will not be immediately aborted and will instead be cleaned up once they return to an `idle` state. They will remain exposed via `useFetchers` while in-flight so you can still access pending/optimistic data after unmount.

.changeset/fetcher-ref-count.md

@@ -0,0 +1,8 @@
+---
+"@remix-run/router": minor
+---
+
+When `v7_fetcherPersist` is enabled, the router now performs ref-counting on fetcher keys via `getFetcher`/`deleteFetcher` so it knows when a given fetcher is totally unmounted from the UI
+
+- Once a fetcher has been totally unmounted, we can ignore post-processing of a persisted fetcher result such as a redirect or an error
+- The router will also pass a new `deletedFetchers` array to the subscriber callbacks so that the UI layer can remove associated fetcher data

.changeset/fix-router-future-prop.md

@@ -3,4 +3,4 @@
 "react-router-dom": patch
 ---
 
-Fix the `future`prop on `BrowserRouter`, `HashRouter` and `MemoryRouter` so that it accepts a `Partial<FutureConfig>` instead of requiring all flags to be included.
+Fix the `future` prop on `BrowserRouter`, `HashRouter` and `MemoryRouter` so that it accepts a `Partial<FutureConfig>` instead of requiring all flags to be included.

package.json

@@ -110,7 +110,7 @@
   },
   "filesize": {
     "packages/router/dist/router.umd.min.js": {
-      "none": "48.7 kB"
+      "none": "49.0 kB"
     },
     "packages/react-router/dist/react-router.production.min.js": {
       "none": "13.9 kB"
@@ -119,10 +119,10 @@
       "none": "16.3 kB"
     },
     "packages/react-router-dom/dist/react-router-dom.production.min.js": {
-      "none": "16.5 kB"
+      "none": "16.1 kB"
     },
     "packages/react-router-dom/dist/umd/react-router-dom.production.min.js": {
-      "none": "22.7 kB"
+      "none": "22.3 kB"
     }
   }
 }