feat(chat): preserve message drafts in session temp store

frontend/composables/useChatDraft.js

@@ -0,0 +1,43 @@
+export function useChatDraft(roomKey, { persist = true } = {}) {
+    const auth = useAuthStore()
+    const temp = useTempStore()
+    const apiBase = useRuntimeConfig().public.apiBase
+    const localDraft = ref(null)
+    const key = computed(() => {
+        const room = toValue(roomKey), user = auth.user?.id || auth.user?.user_id
+        return toValue(persist) && room && user && auth.activeTenant
+            ? JSON.stringify([apiBase, user, String(auth.activeTenant), auth.profile?.id || '', room])
+            : null
+    })
+    watch([key, () => toValue(roomKey), () => auth.user?.id || auth.user?.user_id,
+        () => auth.activeTenant, () => auth.profile?.id], () => { localDraft.value = null }, { flush: 'sync' })
+    const current = () => key.value ? temp.getChatDraft(key.value) : localDraft.value
+    function update(patch) {
+        const value = { text: '', image: null, ...current(), ...patch, clientId: crypto.randomUUID() }
+        const next = value.text || value.image ? value : null
+        if (key.value) temp.setChatDraft(key.value, next)
+        else localDraft.value = next
+    }
+    const draft = computed({ get: () => current()?.text || '', set: text => update({ text }) })
+    const draftImage = computed({ get: () => current()?.image || null, set: image => update({ image }) })
+    const draftSending = computed(() => !!key.value && temp.isChatDraftSending(key.value))
+    const captureDraft = () => ({ key: key.value, value: current() })
+    function startDraftSend() {
+        if (draftSending.value) return null
+        const snapshot = captureDraft()
+        if (!snapshot.value) return null
+        if (snapshot.key) temp.startChatDraftSend(snapshot.key, snapshot.value.clientId)
+        return snapshot
+    }
+    function finishDraftSend(snapshot) {
+        if (snapshot.key) temp.finishChatDraftSend(snapshot.key, snapshot.value.clientId)
+    }
+    function clearDraft(snapshot) {
+        const saved = snapshot.key ? temp.getChatDraft(snapshot.key) : localDraft.value
+        // A late send response must only remove the draft that was actually sent.
+        if (!snapshot.value || saved?.clientId !== snapshot.value.clientId) return
+        if (snapshot.key) temp.setChatDraft(snapshot.key, null)
+        else localDraft.value = null
+    }
+    return { draft, draftImage, draftSending, captureDraft, clearDraft, startDraftSend, finishDraftSend }
+}