refactor: app state handling

1. fixes snapshot patches not being included
2. fixes all mutations being passed when syncing from scratch
3. simpler chat mutation model
4. do not retry if key is not found

src/Utils/chat-utils.ts

@@ -187,7 +187,7 @@ export const decodeSyncdMutations = async(
         if(!key) {
             const keyEnc = await getAppStateSyncKey(base64Key)
             if(!keyEnc) {
-                throw new Boom(`failed to find key "${base64Key}" to decode mutation`, { statusCode: 500, data: { msgMutations } })
+                throw new Boom(`failed to find key "${base64Key}" to decode mutation`, { statusCode: 404, data: { msgMutations } })
             }
             const result = mutationKeys(keyEnc.keyData!)
             keyCache[base64Key] = result
@@ -229,17 +229,16 @@ export const decodeSyncdMutations = async(
             }
         }
 
-        const indexStr = Buffer.from(syncAction.index).toString()
-        const mutation: ChatMutation = {
+        const indexStr = Buffer.from(syncAction.index).toString() 
+        mutations.push({
             syncAction,
             index: JSON.parse(indexStr),
+        })
+        ltGenerator.mix({ 
             indexMac: record.index!.blob!,
             valueMac: ogValueMac,
-            operation: operation,
-        }
-        mutations.push(mutation)
-
-        ltGenerator.mix(mutation)
+            operation: operation
+        })
     }
 
     return { mutations, ...ltGenerator.finish() }
@@ -339,20 +338,15 @@ export const decodeSyncdSnapshot = async(
     name: WAPatchName,
     snapshot: proto.ISyncdSnapshot,
     getAppStateSyncKey: FetchAppStateSyncKey,
+    minimumVersionNumber: number | undefined,
     validateMacs: boolean = true
 ) => {
     const newState = newLTHashState()
     newState.version = toNumber(snapshot.version!.version!)
     
-    const records = snapshot.records!
-
-    const ltGenerator = makeLtHashGenerator(newState)
-    for(const { index, value } of records) {
-        const valueMac = value.blob!.slice(-32)!
-        ltGenerator.mix({ indexMac: index.blob!, valueMac, operation: 0 })
-    }
-
-    Object.assign(newState, ltGenerator.finish())
+    let { hash, indexValueMap, mutations } = await decodeSyncdMutations(snapshot.records!, newState, getAppStateSyncKey, validateMacs)
+    newState.hash = hash
+    newState.indexValueMap = indexValueMap
 
     if(validateMacs) {
         const base64Key = Buffer.from(snapshot.keyId!.id!).toString('base64')
@@ -367,7 +361,15 @@ export const decodeSyncdSnapshot = async(
         }
     }
 
-    return newState
+    const areMutationsRequired = typeof minimumVersionNumber === 'undefined' || newState.version > minimumVersionNumber
+    if(!areMutationsRequired) {
+        mutations = []
+    }
+
+    return {
+        state: newState,
+        mutations
+    }
 }
 
 export const decodePatches = async(
@@ -375,6 +377,7 @@ export const decodePatches = async(
     syncds: proto.ISyncdPatch[],
     initial: LTHashState,
     getAppStateSyncKey: FetchAppStateSyncKey,
+    minimumVersionNumber?: number,
     validateMacs: boolean = true
 ) => {
     const successfulMutations: ChatMutation[] = []
@@ -390,14 +393,18 @@ export const decodePatches = async(
             const ref = await downloadExternalPatch(syncd.externalMutations)
             syncd.mutations.push(...ref.mutations)
         }
+
+        const patchVersion = toNumber(version.version!)
         
-        newState.version = toNumber(version.version!)
+        newState.version = patchVersion
 
         const decodeResult = await decodeSyncdPatch(syncd, name, newState, getAppStateSyncKey, validateMacs)
 
         newState.hash = decodeResult.hash
         newState.indexValueMap = decodeResult.indexValueMap
-        successfulMutations.push(...decodeResult.mutations)
+        if(typeof minimumVersionNumber === 'undefined' || patchVersion > minimumVersionNumber) {
+            successfulMutations.push(...decodeResult.mutations)
+        }
         
         if(validateMacs) {
             const base64Key = Buffer.from(keyId!.id!).toString('base64')