Add debug-composer route

src/Navigation.tsx

@@ -55,6 +55,7 @@ import {
 import {useCloseAllActiveElements} from '#/state/util'
 import {CommunityGuidelinesScreen} from '#/view/screens/CommunityGuidelines'
 import {CopyrightPolicyScreen} from '#/view/screens/CopyrightPolicy'
+import {DebugComposerScreen} from '#/view/screens/DebugComposer'
 import {DebugModScreen} from '#/view/screens/DebugMod'
 import {FeedsScreen} from '#/view/screens/Feeds'
 import {HomeScreen} from '#/view/screens/Home'
@@ -309,6 +310,11 @@ function commonScreens(Stack: typeof Flat, unreadCountLabel?: string) {
         getComponent={() => DebugModScreen}
         options={{title: title(msg`Moderation states`), requireAuth: true}}
       />
+      <Stack.Screen
+        name="DebugComposer"
+        getComponent={() => DebugComposerScreen}
+        options={{title: title(msg`Composer V2`), requireAuth: true}}
+      />
       <Stack.Screen
         name="SharedPreferencesTester"
         getComponent={() => SharedPreferencesTesterScreen}

src/components/ComposerV2/hooks/ThreadStoreContext.tsx

@@ -0,0 +1,31 @@
+import {createContext, useContext} from 'react'
+
+import {type createThreadStore} from '#/components/ComposerV2/store'
+
+export type ThreadStore = ReturnType<typeof createThreadStore>
+
+const ThreadStoreContext = createContext<ThreadStore | null>(null)
+
+export function ThreadStoreProvider({
+  store,
+  children,
+}: {
+  store: ThreadStore
+  children: React.ReactNode
+}) {
+  return (
+    <ThreadStoreContext.Provider value={store}>
+      {children}
+    </ThreadStoreContext.Provider>
+  )
+}
+
+export function useThreadStore(): ThreadStore {
+  const store = useContext(ThreadStoreContext)
+  if (!store) {
+    throw new Error(
+      'useThreadStore must be used inside a <ThreadStoreProvider>',
+    )
+  }
+  return store
+}

src/components/ComposerV2/hooks/index.ts

@@ -0,0 +1,8 @@
+export {
+  type ThreadStore,
+  ThreadStoreProvider,
+  useThreadStore,
+} from '#/components/ComposerV2/hooks/ThreadStoreContext'
+export {useThreadPost} from '#/components/ComposerV2/hooks/useThreadPost'
+export {useThreadPostRichText} from '#/components/ComposerV2/hooks/useThreadPostRichText'
+export {useThreadState} from '#/components/ComposerV2/hooks/useThreadState'

src/components/ComposerV2/hooks/useThreadPost.ts

@@ -0,0 +1,18 @@
+import {useSyncExternalStore} from 'react'
+
+import {useThreadStore} from '#/components/ComposerV2/hooks/ThreadStoreContext'
+import {type ThreadPost} from '#/components/ComposerV2/store/types'
+
+/**
+ * Subscribe to a single post by id. Returns undefined if no such post
+ * exists. Rerenders only when this specific post's reference changes -
+ * unrelated post mutations don't propagate here because the store's
+ * actions spread `{...post, ...}` only on the touched post.
+ */
+export function useThreadPost(postId: string): ThreadPost | undefined {
+  const store = useThreadStore()
+  return useSyncExternalStore(
+    store.subscribe,
+    () => store.getState().posts[postId],
+  )
+}

src/components/ComposerV2/hooks/useThreadPostRichText.ts

@@ -0,0 +1,30 @@
+import {useMemo} from 'react'
+import {RichText} from '@atproto/api'
+
+import {shortenLinks} from '#/lib/strings/rich-text-manip'
+import {useThreadPost} from '#/components/ComposerV2/hooks/useThreadPost'
+
+/**
+ * Derived RichText for a post's text. Recomputes only when the underlying
+ * `text` changes (not on unrelated mutations like alt-text or upload
+ * status). detectFacetsWithoutResolution is regex-only, so this is cheap
+ * to run per-keystroke for typical post lengths.
+ *
+ * `shortenedGraphemeLength` matches the value the existing draft adapter
+ * stores - the count after URL shortening, used for the post char limit.
+ */
+export function useThreadPostRichText(postId: string): {
+  richtext: RichText
+  shortenedGraphemeLength: number
+} {
+  const post = useThreadPost(postId)
+  const text = post?.text ?? ''
+  return useMemo(() => {
+    const richtext = new RichText({text})
+    richtext.detectFacetsWithoutResolution()
+    return {
+      richtext,
+      shortenedGraphemeLength: shortenLinks(richtext).graphemeLength,
+    }
+  }, [text])
+}

src/components/ComposerV2/hooks/useThreadState.ts

@@ -0,0 +1,13 @@
+import {useSyncExternalStore} from 'react'
+
+import {useThreadStore} from '#/components/ComposerV2/hooks/ThreadStoreContext'
+import {type ThreadState} from '#/components/ComposerV2/store/types'
+
+/**
+ * Subscribe to the full thread state. Rerenders whenever any post changes.
+ * For finer-grained subscriptions use `useThreadPost(id)`.
+ */
+export function useThreadState(): ThreadState {
+  const store = useThreadStore()
+  return useSyncExternalStore(store.subscribe, store.getState)
+}

src/components/ComposerV2/store/index.ts

@@ -62,14 +62,17 @@ export function createThreadStore(options: {
   /**
    * Action bodies mutate `s` in place. Returning `null` signals a no-op (the
    * state ref is preserved and listeners are not notified). Otherwise we
-   * shallow-clone the top-level object so getState() returns a new reference,
+   * shallow-clone both the top-level state and the inner `posts` object so
-   * which is what useSyncExternalStore needs to trigger a rerender.
+   * any consumer of either reference sees a fresh value. (Some actions
+   * mutate `s.posts` in place, e.g. removePost's `delete s.posts[id]`;
+   * cloning posts here means selectors and React Compiler memoization can
+   * use ref equality reliably.)
    */
   function mutateState(fn: (s: types.ThreadState) => types.ThreadState | null) {
     if (destroyed) return
     const next = fn(state)
     if (next === null) return
-    state = {...next}
+    state = {...next, posts: {...next.posts}}
     for (const listener of listeners) listener()
   }
 

src/lib/routes/types.ts

@@ -34,6 +34,7 @@ export type CommonNavigatorParams = {
   ProfileLabelerLikedBy: {name: string}
   Debug: undefined
   DebugMod: undefined
+  DebugComposer: undefined
   SharedPreferencesTester: undefined
   Log: undefined
   Support: undefined

src/routes.ts

@@ -39,6 +39,7 @@ export const router = new Router<AllNavigatableRoutes>({
   // debug
   Debug: '/sys/debug',
   DebugMod: '/sys/debug-mod',
+  DebugComposer: '/sys/debug-composer',
   Log: '/sys/log',
   // settings
   LanguageSettings: '/settings/language',

src/view/screens/DebugComposer/DebugComposer.tsx

@@ -0,0 +1,181 @@
+/**
+ * Minimal end-to-end playground for the ComposerV2 store. Wires a single
+ * Composer text input to the store's root post, surfaces the live state
+ * as a monospace dump, and exposes a few action buttons so we can poke at
+ * the surface (addPost, removeEmbed, removeQuote) without building the
+ * full UI yet.
+ *
+ * Useful for verifying:
+ *   - useSyncExternalStore actually rerenders on store mutations
+ *   - onFacetCommitted -> addUri produces the expected pending/resolved/
+ *     failed embed or quote states
+ *   - addUri validation (embedding-disabled, embed/media exclusion) shows
+ *     up the way we expect
+ */
+import {useMemo, useState} from 'react'
+import {ScrollView, View} from 'react-native'
+
+import {useAgent} from '#/state/session'
+import {atoms as a, useTheme} from '#/alf'
+import {Button, ButtonText} from '#/components/Button'
+import {Composer} from '#/components/Composer'
+import {
+  ThreadStoreProvider,
+  useThreadPost,
+  useThreadPostRichText,
+  useThreadState,
+  useThreadStore,
+} from '#/components/ComposerV2/hooks'
+import {createThreadStore} from '#/components/ComposerV2/store'
+import {Text} from '#/components/Typography'
+
+export default function DebugComposer() {
+  const agent = useAgent()
+  const [store] = useState(() => createThreadStore({agent}))
+  return (
+    <ThreadStoreProvider store={store}>
+      <View style={[a.p_md, a.gap_md]}>
+        <PostList />
+        <Toolbar />
+        <StateDump />
+      </View>
+    </ThreadStoreProvider>
+  )
+}
+
+function PostList() {
+  const state = useThreadState()
+  const postIds = Object.keys(state.posts)
+  return (
+    <View style={[a.gap_md]}>
+      {postIds.map((postId, i) => (
+        <PostRow key={postId} postId={postId} index={i} />
+      ))}
+    </View>
+  )
+}
+
+function PostRow({postId, index}: {postId: string; index: number}) {
+  const post = useThreadPost(postId)
+  const store = useThreadStore()
+  const t = useTheme()
+
+  // Composer is uncontrolled - defaultValue is read once on mount and the
+  // input owns its text after that. We mirror every change back into the
+  // store via onChange.
+  const initialText = useMemo(() => post?.text ?? '', [])
+
+  if (!post) return null
+
+  return (
+    <View
+      style={[
+        a.p_sm,
+        a.rounded_md,
+        a.border,
+        t.atoms.border_contrast_low,
+        t.atoms.bg_contrast_25,
+        a.gap_sm,
+      ]}>
+      <View style={[a.flex_row, a.justify_between, a.align_center]}>
+        <Text style={[a.text_xs, {fontFamily: 'monospace'}]}>
+          [{index}] {postId}
+        </Text>
+        {index > 0 && (
+          <Button
+            label={`Remove post ${index}`}
+            size="tiny"
+            color="secondary"
+            onPress={() => store.actions.removePost(postId)}>
+            <ButtonText>x</ButtonText>
+          </Button>
+        )}
+      </View>
+      <Composer
+        label="Post text"
+        placeholder="What's up? Paste a URL to test addUri."
+        defaultValue={initialText}
+        onChange={text => store.actions.setPostText(postId, text)}
+        onFacetCommitted={facet => {
+          if (facet.type === 'url') {
+            store.actions.addUri(postId, facet.value)
+          }
+        }}
+      />
+      <PostFooter postId={postId} />
+    </View>
+  )
+}
+
+function PostFooter({postId}: {postId: string}) {
+  const {shortenedGraphemeLength} = useThreadPostRichText(postId)
+  const store = useThreadStore()
+  return (
+    <View style={[a.flex_row, a.flex_wrap, a.gap_sm, a.align_center]}>
+      <Text style={[a.text_xs, {fontFamily: 'monospace'}]}>
+        graphemes: {shortenedGraphemeLength} / 300
+      </Text>
+      <Button
+        label="Remove embed"
+        size="tiny"
+        color="secondary"
+        onPress={() => store.actions.removeEmbed(postId)}>
+        <ButtonText>- embed</ButtonText>
+      </Button>
+      <Button
+        label="Remove quote"
+        size="tiny"
+        color="secondary"
+        onPress={() => store.actions.removeQuoteEmbed(postId)}>
+        <ButtonText>- quote</ButtonText>
+      </Button>
+    </View>
+  )
+}
+
+function Toolbar() {
+  const store = useThreadStore()
+  return (
+    <View style={[a.flex_row, a.flex_wrap, a.gap_sm]}>
+      <Button
+        label="Append post"
+        size="small"
+        color="secondary"
+        onPress={() => {
+          // Read live state at click time so we always append after the
+          // current last post (instead of capturing a stale id at render).
+          const ids = Object.keys(store.getState().posts)
+          const lastId = ids[ids.length - 1]
+          if (lastId) store.actions.addPost('after', lastId)
+        }}>
+        <ButtonText>+ post</ButtonText>
+      </Button>
+    </View>
+  )
+}
+
+function StateDump() {
+  const state = useThreadState()
+  const t = useTheme()
+
+  // Functions (e.g. retry on failed states) are dropped by JSON.stringify;
+  // BlobRef and AppBskyFeedDefs view types serialize as plain objects.
+  const dump = useMemo(() => JSON.stringify(state, null, 2), [state])
+
+  return (
+    <View
+      style={[
+        a.rounded_md,
+        a.border,
+        t.atoms.border_contrast_low,
+        t.atoms.bg_contrast_25,
+      ]}>
+      <ScrollView
+        horizontal
+        showsHorizontalScrollIndicator={false}
+        contentContainerStyle={[a.p_md]}>
+        <Text style={[a.text_xs, {fontFamily: 'monospace'}]}>{dump}</Text>
+      </ScrollView>
+    </View>
+  )
+}

src/view/screens/DebugComposer/index.tsx

@@ -0,0 +1,24 @@
+import {lazy, Suspense} from 'react'
+
+import * as Layout from '#/components/Layout'
+
+const DebugComposer = lazy(() => import('./DebugComposer'))
+
+export function DebugComposerScreen() {
+  return (
+    <Layout.Screen>
+      <Layout.Header.Outer>
+        <Layout.Header.BackButton />
+        <Layout.Header.Content>
+          <Layout.Header.TitleText>Composer V2</Layout.Header.TitleText>
+        </Layout.Header.Content>
+        <Layout.Header.Slot />
+      </Layout.Header.Outer>
+      <Layout.Content keyboardShouldPersistTaps="handled">
+        <Suspense fallback={null}>
+          <DebugComposer />
+        </Suspense>
+      </Layout.Content>
+    </Layout.Screen>
+  )
+}