diff --git a/nodes/config/ui_base.js b/nodes/config/ui_base.js
index ebedfdd55..7fab5e2b0 100644
--- a/nodes/config/ui_base.js
+++ b/nodes/config/ui_base.js
@@ -34,6 +34,8 @@ module.exports = function (RED) {
     datastore.setConfig(RED)
     statestore.setConfig(RED)
 
+    let warnedStoreUnavailable = false
+
     /**
      * @typedef {import('socket.io').Socket} Socket
      * @typedef {import('socket.io').Server} Server
@@ -395,13 +397,12 @@ module.exports = function (RED) {
                 onUnavailable: (err) => { unavailable = err },
                 onReplaced: () => node.warn('global.dashboardStore was replaced by a flow since the last deploy, discarding the stored value of every widget. The store has been re-created. To write your own data, set global.dashboardStore.<key> rather than replacing global.dashboardStore itself.')
             })
-            if (!store) {
-                datastore.disableStore()
-                node.warn('Dashboard data store disabled: the global context store doesn\'t hold objects by reference (e.g. cache: false), so live state can\'t work. Use the memory store or localfilesystem with cache: true.' + (unavailable ? ' Reading it failed with: ' + unavailable.message : ''))
+            if (!store && !warnedStoreUnavailable) {
+                warnedStoreUnavailable = true
+                node.warn('Dashboard data store: flows can\'t use global.dashboardStore, because the default context store doesn\'t keep values in memory (e.g. localfilesystem with cache: false). Dashboards still work normally. To use global.dashboardStore from flows, set contextStorage.default to memory, or localfilesystem with cache: true.' + (unavailable ? ' (Reason: ' + unavailable.message + ')' : ''))
             }
         } catch (err) {
-            datastore.disableStore()
-            node.warn('Dashboard data store disabled: could not initialise it in global context (' + err.message + ').')
+            node.warn('Dashboard data store: flows can\'t use global.dashboardStore, because saving it to global context failed (' + err.message + '). Dashboards still work normally.')
         }
 
         n.root = RED.settings.httpNodeRoot || '/'
diff --git a/nodes/store/data.js b/nodes/store/data.js
index 00799efbb..928103a11 100644
--- a/nodes/store/data.js
+++ b/nodes/store/data.js
@@ -1,23 +1,21 @@
 const { isClientScoped } = require('../utils/index.js')
 
-const { attachToContext, MERGE_ENTRY, APPEND_ENTRY, SET_SERIES, TRIM_SERIES } = require('./reactive.js')
-
-const data = {}
+const { createDataStore, attachToContext, MERGE_ENTRY, APPEND_ENTRY, SET_SERIES, TRIM_SERIES, ENTRY_MSG } = require('./reactive.js')
 
 const config = {
     RED: null
 }
 
 let storeOptions = {}
-let storeEnabled = false
+let fallbackStore = null
 let storeContext = null
 let storeBase = null
 let warned = false
 
-function warnOnce (node, problem) {
-    if (warned || !node) return
+function warnOnce (problem) {
+    if (warned || !storeBase) return
     warned = true
-    node.warn(`Dashboard data store: ${problem}. Further store failures are not reported until the next full deploy or restart.`)
+    storeBase.warn(`Dashboard data store: ${problem}. Further store failures are not reported until the next full deploy or restart.`)
 }
 
 const attachOptions = () => ({ clone: config.RED.util.cloneMessage, ...storeOptions })
@@ -29,48 +27,28 @@ function getOrCreateStore (globalContext) {
     return store
 }
 
+function getStoreOrWarn (action, id) {
+    try {
+        return fallbackStore || getOrCreateStore(storeContext)
+    } catch (err) { warnOnce(`${action} ${id} failed (${err.message})`) }
+}
+
 function initStore (globalContext, { node, ...opts } = {}) {
     storeOptions = opts
-    storeEnabled = true
     storeContext = globalContext
     storeBase = node
     warned = false
-    return attachToContext(globalContext, attachOptions())
-}
-
-function disableStore () {
-    storeEnabled = false
-}
-
-function writeToStore (node, msg) {
-    if (!storeEnabled) return
-    if (!msg || typeof msg !== 'object') return
-    try {
-        getOrCreateStore(node.context().global)[MERGE_ENTRY](node.id, msg)
-    } catch (err) { warnOnce(node, `a store write failed (${err.message}), so global.dashboardStore may be out of date`) }
-}
-
-function appendToStore (node, msg) {
-    if (!storeEnabled) return
-    if (!msg || typeof msg !== 'object') return
-    try {
-        getOrCreateStore(node.context().global)[APPEND_ENTRY](node.id, msg)
-    } catch (err) { warnOnce(node, `a store write failed (${err.message}), so global.dashboardStore may be out of date`) }
-}
-
-function replaceInStore (node, msgs) {
-    if (!storeEnabled) return
-    if (!Array.isArray(msgs) || msgs.some((m) => !m || typeof m !== 'object')) return
-    try {
-        getOrCreateStore(node.context().global)[SET_SERIES](node.id, msgs)
-    } catch (err) { warnOnce(node, `a store write failed (${err.message}), so global.dashboardStore may be out of date`) }
-}
-
-function trimInStore (node, trim) {
-    if (!storeEnabled) return
+    let store = null
     try {
-        getOrCreateStore(node.context().global)[TRIM_SERIES](node.id, trim)
-    } catch (err) { warnOnce(node, `a store write failed (${err.message}), so global.dashboardStore may be out of date`) }
+        store = attachToContext(globalContext, attachOptions())
+    } finally {
+        if (store) {
+            fallbackStore = null
+        } else if (!fallbackStore) {
+            fallbackStore = createDataStore(attachOptions())
+        }
+    }
+    return store
 }
 
 function latestPerTopic (msgs, maxPoints) {
@@ -120,26 +98,17 @@ function canSaveInStore (base, node, msg) {
     return checks.length === 0 || !checks.includes(false)
 }
 
-// Strip msg of properties that are not needed for storage
-function stripMsg (msg) {
-    const newMsg = config.RED.util.cloneMessage(msg)
-
-    // don't need to store ui_updates in the datastore, as this is handled in statestore
-    delete newMsg.ui_update
-
-    return newMsg
-}
-
 const getters = {
     RED () {
         return config.RED
     },
     // given a widget id, return the latest msg received
     msg (id) {
-        return config.RED.util.cloneMessage(data[id])
+        return config.RED.util.cloneMessage(getStoreOrWarn('reading', id)?.[ENTRY_MSG](id))
     },
     has (id) {
-        return !!data[id]
+        const store = getStoreOrWarn('reading', id)
+        return !!store && id in store
     }
 }
 
@@ -150,13 +119,10 @@ const setters = {
     },
     // remove data associated to a given widget
     clear (id) {
-        delete data[id]
-        if (!storeEnabled) {
-            return
+        const store = getStoreOrWarn('clearing', id)
+        if (store) {
+            delete store[id]
         }
-        try {
-            delete getOrCreateStore(storeContext)[id]
-        } catch (err) { warnOnce(storeBase, `clearing the store entry for ${id} failed (${err.message}), so global.dashboardStore may still hold its old value`) }
     },
     /**
      *
@@ -166,35 +132,20 @@ const setters = {
      */
     save (base, node, msg) {
         if (Array.isArray(msg)) {
-            /// need to check msg by msg
-            const filtered = []
-            for (const m of msg) {
-                if (canSaveInStore(base, node, m)) {
-                    filtered.push(config.RED.util.cloneMessage(m))
-                }
-            }
-            data[node.id] = filtered
-            replaceInStore(node, filtered)
-        } else {
-            if (canSaveInStore(base, node, msg)) {
-                const newMsg = stripMsg(msg)
-                data[node.id] = {
-                    ...data[node.id],
-                    ...newMsg
-                }
-                writeToStore(node, newMsg)
+            const msgs = msg.filter((m) => canSaveInStore(base, node, m))
+            if (msgs.every((m) => m && typeof m === 'object')) {
+                getStoreOrWarn('saving', node.id)?.[SET_SERIES](node.id, msgs)
             }
+        } else if (msg && typeof msg === 'object' && canSaveInStore(base, node, msg)) {
+            const { ui_update: uiUpdate, ...rest } = msg
+            getStoreOrWarn('saving', node.id)?.[MERGE_ENTRY](node.id, rest)
         }
     },
     // given a widget id, and msg, store in an array of history of values
     // useful for charting widgets
     append (base, node, msg) {
-        if (canSaveInStore(base, node, msg)) {
-            if (!data[node.id]) {
-                data[node.id] = []
-            }
-            data[node.id].push(config.RED.util.cloneMessage(msg))
-            appendToStore(node, msg)
+        if (msg && typeof msg === 'object' && canSaveInStore(base, node, msg)) {
+            getStoreOrWarn('saving', node.id)?.[APPEND_ENTRY](node.id, msg)
         }
     },
     /**
@@ -204,28 +155,12 @@ const setters = {
      * @param {(msg) => Boolean} filterFunction
      */
     filter (base, node, filterFunction) {
-        const currentData = data[node.id]
-        if (filterFunction && Array.isArray(currentData) && currentData.length) {
-            const filteredMessages = currentData.filter(filterFunction)
-            if (filteredMessages.length !== currentData.length) {
-                // no need for save operation to process messages - just apply them
-                data[node.id] = filteredMessages
-            }
-        }
         if (filterFunction) {
-            trimInStore(node, (msgs) => msgs.filter(filterFunction))
+            getStoreOrWarn('trimming', node.id)?.[TRIM_SERIES](node.id, (msgs) => msgs.filter(filterFunction))
         }
     },
     keepLatestPerTopic (base, node, maxPoints) {
-        trimInStore(node, (msgs) => latestPerTopic(msgs, maxPoints))
-        const currentData = data[node.id]
-        if (!Array.isArray(currentData)) {
-            return
-        }
-        const kept = latestPerTopic(currentData, maxPoints)
-        if (kept.length !== currentData.length) {
-            data[node.id] = kept
-        }
+        getStoreOrWarn('trimming', node.id)?.[TRIM_SERIES](node.id, (msgs) => latestPerTopic(msgs, maxPoints))
     }
 }
 
@@ -239,6 +174,5 @@ module.exports = {
     filter: setters.filter,
     keepLatestPerTopic: setters.keepLatestPerTopic,
     clear: setters.clear,
-    initStore,
-    disableStore
+    initStore
 }
diff --git a/nodes/store/reactive.js b/nodes/store/reactive.js
index 858a4fb74..a4ca049d6 100644
--- a/nodes/store/reactive.js
+++ b/nodes/store/reactive.js
@@ -3,6 +3,7 @@ const APPEND_ENTRY = Symbol.for('@flowfuse/node-red-dashboard/appendEntry')
 const SET_SERIES = Symbol.for('@flowfuse/node-red-dashboard/setSeries')
 const MERGE_ENTRY = Symbol.for('@flowfuse/node-red-dashboard/mergeEntry')
 const TRIM_SERIES = Symbol.for('@flowfuse/node-red-dashboard/trimSeries')
+const ENTRY_MSG = Symbol.for('@flowfuse/node-red-dashboard/entryMsg')
 const TRIM_BATCH = 60
 const NAMESPACE = 'dashboardStore'
 
@@ -41,7 +42,6 @@ function deepReactive (value, notify, path, clone, seen = new WeakMap()) {
     if (!isReactable(value)) return value
     if (seen.has(value)) return seen.get(value)
     const proxy = new Proxy(value, {
-        get (t, p, r) { return Reflect.get(t, p, r) },
         set (t, p, v) {
             if (typeof p === 'symbol') return Reflect.set(t, p, v)
             // a push writes the new index then grows length; only a shrink is a change worth reporting
@@ -112,6 +112,12 @@ function createDataStore ({ maxHistory = 5, onChange, clone = deepClone, now = D
     }
 
     const trimmedSeries = (rec) => rec.trims ? rec.trims.kept.concat(rec.msg.slice(rec.trims.seen)) : rec.msg.slice()
+    const msgOf = (rec) => Array.isArray(rec.msg) ? Object.freeze(trimmedSeries(rec)) : rec.msg
+
+    records[ENTRY_MSG] = (prop) => {
+        const rec = records[prop]
+        return rec ? msgOf(rec) : undefined
+    }
 
     records[MERGE_ENTRY] = (prop, msg) => {
         const current = records[prop]
@@ -119,8 +125,10 @@ function createDataStore ({ maxHistory = 5, onChange, clone = deepClone, now = D
         const previous = Array.isArray(current?.msg) ? freezeOwned(cloneValue({ ...trimmedSeries(current) })) : current?.msg || {}
         const { payload: storedPayload, ...stored } = previous
         const keepValue = current && !Array.isArray(current.msg) && !('payload' in msg)
-        const rec = keepValue ? current : writeValue(prop, cloneValue(payload))
-        const fields = { ...stored, ...freezeOwned(cloneValue(incoming)) }
+        const owned = freezeOwned(cloneValue(incoming))
+        const value = keepValue ? undefined : cloneValue(payload)
+        const rec = keepValue ? current : writeValue(prop, value)
+        const fields = { ...stored, ...owned }
         const hasPayload = 'payload' in msg || (keepValue && 'payload' in current.msg)
         rec.msg = Object.freeze(hasPayload ? { ...fields, payload: rec.value } : fields)
         rec.timestamp = now()
@@ -163,13 +171,13 @@ function createDataStore ({ maxHistory = 5, onChange, clone = deepClone, now = D
     records[APPEND_ENTRY] = (prop, msg) => {
         let rec = records[prop]
         const replaced = !!rec && !(Array.isArray(rec.value) && Array.isArray(rec.msg))
+        // the proxy clones on push, so points must not be cloned again here
+        const { _datapoint, ...rest } = msg
+        const owned = cloneValue(rest)
         if (!rec || replaced) {
             rec = writeValue(prop, [])
             rec.msg = []
         }
-        // the proxy clones on push, so points must not be cloned again here
-        const { _datapoint, ...rest } = msg
-        const owned = cloneValue(rest)
         const start = rec.value.length
         for (const p of pointsOf(_datapoint)) rec.value.push(p)
         const stored = toStoredDatapoint(rec.value, _datapoint, start, rec.value.length)
@@ -208,7 +216,7 @@ function createDataStore ({ maxHistory = 5, onChange, clone = deepClone, now = D
             if (prop.startsWith('$')) {
                 const rec = target[prop.slice(1)]
                 if (!rec) return undefined
-                const msg = Array.isArray(rec.msg) ? Object.freeze(trimmedSeries(rec)) : rec.msg
+                const msg = msgOf(rec)
                 return Object.freeze({ value: rec.value, msg, quality: rec.quality, timestamp: rec.timestamp, history: Object.freeze(rec.history.slice()) })
             }
             const rec = target[prop]
@@ -241,7 +249,7 @@ function createDataStore ({ maxHistory = 5, onChange, clone = deepClone, now = D
 const injected = new WeakMap()
 
 // Inject the store into global context once. On redeploy the existing store is reused;
-// after a restart with a persistent context store, existing plain data is rehydrated.
+// after a restart it starts fresh and plain data a flow put in its place is copied in.
 // Returns null when the context store can't hold a live proxy: a cache-off store serves
 // only async access so a sync get throws, and a serialising store hands back a copy.
 function attachToContext (globalContext, opts = {}) {
@@ -261,7 +269,7 @@ function attachToContext (globalContext, opts = {}) {
     const previous = injected.get(globalContext)
 
     const store = createDataStore(opts)
-    if (isReactable(existing) && !Array.isArray(existing)) {
+    if (previous && isReactable(existing) && !Array.isArray(existing)) {
         for (const [k, v] of Object.entries(existing)) store[k] = v
     }
     globalContext.set(namespace, store)
@@ -271,4 +279,4 @@ function attachToContext (globalContext, opts = {}) {
     return store
 }
 
-module.exports = { createDataStore, attachToContext, NAMESPACE, STORE, APPEND_ENTRY, SET_SERIES, MERGE_ENTRY, TRIM_SERIES }
+module.exports = { createDataStore, attachToContext, NAMESPACE, STORE, APPEND_ENTRY, SET_SERIES, MERGE_ENTRY, TRIM_SERIES, ENTRY_MSG }
diff --git a/test/nodes/config-nodes/ui_base.spec.js b/test/nodes/config-nodes/ui_base.spec.js
index 84d58f262..f6ef5ce72 100644
--- a/test/nodes/config-nodes/ui_base.spec.js
+++ b/test/nodes/config-nodes/ui_base.spec.js
@@ -153,12 +153,23 @@ describe('ui-base config node: cache-off context store', function () {
         await helper.load(nodeImports, flow)
 
         const warned = helper.log().args.filter((args) =>
-            args[0].level === helper.log().WARN && /hold objects by reference/.test(args[0].msg)
+            args[0].level === helper.log().WARN && /doesn't keep values in memory/.test(args[0].msg)
         )
         warned.should.have.length(1)
         touched.set.should.equal(0)
     })
 
+    it('warns once per start, not on every full deploy', async function () {
+        await helper.load(nodeImports, flow)
+
+        await helper.setFlows(flow, 'full')
+
+        const warned = helper.log().args.filter((args) =>
+            args[0].level === helper.log().WARN && /doesn't keep values in memory/.test(args[0].msg)
+        )
+        warned.should.have.length(1)
+    })
+
     it('stops the write path instead of throwing on every message', async function () {
         await helper.load(nodeImports, flow)
         const text = helper.getNode('node-ui-text')
diff --git a/test/store/data.spec.js b/test/store/data.spec.js
index 2bc0acbc6..60bf94019 100644
--- a/test/store/data.spec.js
+++ b/test/store/data.spec.js
@@ -13,8 +13,14 @@ function fakeGlobal () {
     return { get: (k) => m[k], set: (k, v) => { m[k] = v } }
 }
 
-function fakeNode (id, global) {
-    return { id, type: 'ui-text', context: () => ({ global }), warn: (m) => warnings.push(`${id}: ${m}`) }
+function storeGlobal () {
+    const global = fakeGlobal()
+    datastore.initStore(global, {})
+    return global
+}
+
+function fakeNode (id) {
+    return { id, type: 'ui-text', warn: (m) => warnings.push(`${id}: ${m}`) }
 }
 
 const base = { acceptsClientConfig: [] }
@@ -25,28 +31,27 @@ describe('store: data.js reactive-store mirror', function () {
     })
 
     it('mirrors the clean payload into global.dashboardStore[id], not the whole message', function () {
-        const global = fakeGlobal()
-        const node = fakeNode('w1', global)
+        const global = storeGlobal()
+        const node = fakeNode('w1')
         datastore.save(base, node, { payload: 42, topic: 't', _msgid: 'm', extra: 'x' })
 
         const store = global.get('dashboardStore')
         store.w1.should.equal(42)
-        // the reactive store holds only the value; the whole message stays in the legacy datastore
         datastore.get('w1').payload.should.equal(42)
         datastore.get('w1').topic.should.equal('t')
     })
 
     it('keeps the mirrored value in sync on the latest write', function () {
-        const global = fakeGlobal()
-        const node = fakeNode('w2', global)
+        const global = storeGlobal()
+        const node = fakeNode('w2')
         datastore.save(base, node, { payload: 1 })
         datastore.save(base, node, { payload: 2 })
         global.get('dashboardStore').w2.should.equal(2)
     })
 
     it('stores the whole message alongside the value', function () {
-        const global = fakeGlobal()
-        const node = fakeNode('m1', global)
+        const global = storeGlobal()
+        const node = fakeNode('m1')
         datastore.save(base, node, { payload: 42, topic: 't', extra: 'x' })
 
         const store = global.get('dashboardStore')
@@ -56,28 +61,18 @@ describe('store: data.js reactive-store mirror', function () {
         store.$m1.msg.extra.should.equal('x')
     })
 
-    it('keeps the stored message in step with the legacy merge', function () {
-        const global = fakeGlobal()
-        const node = fakeNode('m3', global)
+    it('merges a later message onto the stored one', function () {
+        storeGlobal()
+        const node = fakeNode('m3')
         datastore.save(base, node, { payload: 1, topic: 'a', unit: 'bar' })
         datastore.save(base, node, { payload: 2 })
 
-        global.get('dashboardStore').$m3.msg.should.eql(datastore.get('m3'))
-    })
-
-    it('does not alias the legacy store into the mirror', function () {
-        const global = fakeGlobal()
-        const node = fakeNode('m4', global)
-        datastore.save(base, node, { payload: 1, topic: 'a' })
-
-        global.get('dashboardStore').$m4.msg.topic = 'mutated'
-
-        datastore.get('m4').topic.should.equal('a')
+        datastore.get('m3').should.eql({ payload: 2, topic: 'a', unit: 'bar' })
     })
 
     it('does not alias the flow\'s message into the store', function () {
-        const global = fakeGlobal()
-        const node = fakeNode('m2', global)
+        const global = storeGlobal()
+        const node = fakeNode('m2')
         const sent = { payload: 1, nested: { a: 1 } }
         datastore.save(base, node, sent)
 
@@ -87,16 +82,17 @@ describe('store: data.js reactive-store mirror', function () {
     })
 
     it('does not mirror a client-scoped message (not stored centrally)', function () {
-        const global = fakeGlobal()
-        const node = fakeNode('w3', global)
+        const global = storeGlobal()
+        const node = fakeNode('w3')
         const scopedBase = { acceptsClientConfig: ['ui-text'] }
         datastore.save(scopedBase, node, { payload: 9, _client: { socketId: 's1' } })
-        should(global.get('dashboardStore')).be.undefined()
+        should(global.get('dashboardStore').w3).be.undefined()
+        datastore.has('w3').should.equal(false)
     })
 
     it('deep-copies a table rows array, so a flow reusing it cannot mutate stored state', function () {
-        const global = fakeGlobal()
-        const node = fakeNode('tbl-1', global)
+        const global = storeGlobal()
+        const node = fakeNode('tbl-1')
         const rows = [{ id: 1, name: 'a', meta: { site: { rack: 'r1' } } }]
 
         datastore.save(base, node, { payload: rows })
@@ -108,30 +104,30 @@ describe('store: data.js reactive-store mirror', function () {
         ])
     })
 
-    it('keeps the mirrored rows independent of the legacy datastore', function () {
-        const global = fakeGlobal()
-        const node = fakeNode('tbl-2', global)
+    it('reads a value only a flow wrote', function () {
+        const global = storeGlobal()
 
-        datastore.save(base, node, { payload: [{ id: 1, name: 'original' }] })
-        global.get('dashboardStore')['tbl-2'][0].name = 'changed via store'
+        global.get('dashboardStore')['flow-only'] = 5
 
-        datastore.get('tbl-2').payload.should.eql([{ id: 1, name: 'original' }])
+        datastore.has('flow-only').should.equal(true)
+        datastore.get('flow-only').should.eql({ payload: 5 })
     })
 
-    it('does not throw or mirror when the context store cannot hold the proxy', function () {
-        const throwingGlobal = {
-            get: () => { throw new Error('File Store cache disabled - only asynchronous access supported') },
-            set: () => {}
-        }
-        const node = fakeNode('w5', throwingGlobal)
-        should(() => datastore.save(base, node, { payload: 7 })).not.throw()
-        datastore.get('w5').payload.should.equal(7) // legacy datastore still works
+    it('reads what a flow wrote into the stored rows, as a copy the caller owns', function () {
+        const global = storeGlobal()
+        const node = fakeNode('tbl-2')
+
+        datastore.save(base, node, { payload: [{ id: 1, name: 'original' }] })
+        global.get('dashboardStore')['tbl-2'][0].name = 'changed via store'
+        datastore.get('tbl-2').payload[0].name = 'changed by the caller'
+
+        datastore.get('tbl-2').payload.should.eql([{ id: 1, name: 'changed via store' }])
     })
 
     it('clear removes the widget key so a removed widget leaves no orphan', function () {
         const global = fakeGlobal()
         datastore.initStore(global, {})
-        const node = fakeNode('w6', global)
+        const node = fakeNode('w6')
         datastore.save(base, node, { payload: 5 })
         global.get('dashboardStore').w6.should.equal(5)
 
@@ -140,8 +136,8 @@ describe('store: data.js reactive-store mirror', function () {
     })
 
     it('keeps the mirrored value when a later message carries no payload', function () {
-        const global = fakeGlobal()
-        const node = fakeNode('w8', global)
+        const global = storeGlobal()
+        const node = fakeNode('w8')
         datastore.save(base, node, { payload: 'keep me' })
         datastore.save(base, node, { topic: 'no payload' })
 
@@ -151,8 +147,8 @@ describe('store: data.js reactive-store mirror', function () {
     })
 
     it('blanks the mirrored value when a message explicitly carries payload: undefined', function () {
-        const global = fakeGlobal()
-        const node = fakeNode('w11', global)
+        const global = storeGlobal()
+        const node = fakeNode('w11')
         datastore.save(base, node, { payload: 'keep me' })
         datastore.save(base, node, { payload: undefined, topic: 'explicit' })
 
@@ -161,7 +157,7 @@ describe('store: data.js reactive-store mirror', function () {
     })
 
     it('does not throw when a msg is not an object (unchanged from main)', function () {
-        const global = fakeGlobal()
+        const global = storeGlobal()
         for (const msg of ['hello', 42, true]) {
             const node = fakeNode('prim-' + String(msg), global)
             should(() => datastore.save(base, node, msg)).not.throw()
@@ -173,7 +169,7 @@ describe('store: data.js reactive-store mirror', function () {
             get: () => { throw new Error('File Store cache disabled - only asynchronous access supported') },
             set: () => {}
         }
-        const node = fakeNode('w7', throwingGlobal)
+        const node = fakeNode('w7')
         datastore.initStore(throwingGlobal, { node: { warn: () => {} } })
 
         should(() => datastore.clear(node.id)).not.throw()
@@ -187,7 +183,7 @@ describe('store: data.js store options', function () {
 
     it('re-injects with the registered options when a flow replaces the namespace', function () {
         const global = fakeGlobal()
-        const node = fakeNode('w9', global)
+        const node = fakeNode('w9')
         let replaced = 0
         datastore.initStore(global, { onReplaced: () => { replaced++ } })
 
@@ -201,7 +197,7 @@ describe('store: data.js store options', function () {
 
     it('keeps onChange wired through a widget-triggered re-injection', function () {
         const global = fakeGlobal()
-        const node = fakeNode('w10', global)
+        const node = fakeNode('w10')
         const changes = []
         datastore.initStore(global, { onChange: (key) => changes.push(key) })
 
@@ -212,7 +208,7 @@ describe('store: data.js store options', function () {
     })
 })
 
-describe('store: data.js disabled store', function () {
+describe('store: data.js when global context cannot hold the store', function () {
     const cacheOffGlobal = () => ({
         gets: 0,
         get () { this.gets++; throw new Error('File Store cache disabled - only asynchronous access supported') },
@@ -223,37 +219,41 @@ describe('store: data.js disabled store', function () {
         datastore.initStore(fakeGlobal(), {})
     })
 
-    it('stops touching global context once the store is disabled', function () {
+    it('keeps writes off global context and reports no failures', function () {
         const global = cacheOffGlobal()
-        const scalar = fakeNode('w12', global)
-        const chart = fakeNode('w12-chart', global)
-        datastore.initStore(global, { node: { warn: () => {} } })
+        const scalar = fakeNode('w12')
+        const chart = fakeNode('w12-chart')
+        should(datastore.initStore(global, { node: { warn: (m) => warnings.push(m) } })).be.null()
+        warnings.length = 0
         global.gets = 0
-        datastore.disableStore()
 
         datastore.save(base, scalar, { payload: 1 })
         datastore.append(base, chart, { _datapoint: { category: 'a', x: 1, y: 1 } })
         datastore.filter(base, chart, () => false)
+        datastore.keepLatestPerTopic(base, chart, 1)
         datastore.clear(scalar.id)
 
         global.gets.should.equal(0)
+        warnings.should.eql([])
     })
 
-    it('leaves the legacy datastore working while disabled', function () {
-        const global = cacheOffGlobal()
-        const node = fakeNode('w13', global)
-        datastore.disableStore()
+    it('falls back when writing to global context throws', function () {
+        const global = { get: () => undefined, set () { throw new Error('read-only context') } }
+        const node = fakeNode('w13')
+        should(() => datastore.initStore(global, { node: { warn: (m) => warnings.push(m) } })).throw('read-only context')
+        warnings.length = 0
 
-        datastore.save(base, node, { payload: 'legacy still works' })
+        datastore.save(base, node, { payload: 'still works' })
 
-        datastore.get('w13').payload.should.equal('legacy still works')
+        warnings.should.eql([])
+        datastore.get('w13').payload.should.equal('still works')
     })
 
-    it('re-enables on a later initStore', function () {
-        datastore.disableStore()
+    it('goes back to global context on a later initStore', function () {
+        datastore.initStore(cacheOffGlobal(), {})
 
         const global = fakeGlobal()
-        const node = fakeNode('w14', global)
+        const node = fakeNode('w14')
         datastore.initStore(global, {})
         datastore.save(base, node, { payload: 'back on' })
 
@@ -262,17 +262,21 @@ describe('store: data.js disabled store', function () {
 })
 
 describe('store: data.js chart writes', function () {
+    beforeEach(function () {
+        datastore.initStore(fakeGlobal(), {})
+    })
+
     const pt = (x, y, category = 'a') => ({ category, x, y })
 
     // an absent chart key only proves anything if the store is actually working
     function liveStore (global, id) {
-        datastore.save(base, fakeNode(id, global), { payload: 'live' })
+        datastore.save(base, fakeNode(id), { payload: 'live' })
         return global.get('dashboardStore')?.[id]
     }
 
     it('mirrors a chart append into the store', function () {
-        const global = fakeGlobal()
-        const node = fakeNode('chart-1', global)
+        const global = storeGlobal()
+        const node = fakeNode('chart-1')
 
         datastore.append(base, node, { payload: 1, _datapoint: pt(1, 1) })
         datastore.append(base, node, { payload: 2, _datapoint: pt(2, 2) })
@@ -285,8 +289,8 @@ describe('store: data.js chart writes', function () {
     })
 
     it('flattens a multi-series append into several points', function () {
-        const global = fakeGlobal()
-        const node = fakeNode('chart-multi', global)
+        const global = storeGlobal()
+        const node = fakeNode('chart-multi')
 
         datastore.append(base, node, { payload: [1, 5], _datapoint: [pt(1, 1, 'a'), pt(1, 5, 'b')] })
 
@@ -297,8 +301,8 @@ describe('store: data.js chart writes', function () {
     })
 
     it('stores a message with no datapoint but adds no point', function () {
-        const global = fakeGlobal()
-        const node = fakeNode('chart-nodp', global)
+        const global = storeGlobal()
+        const node = fakeNode('chart-nodp')
 
         datastore.append(base, node, { payload: 'x' })
 
@@ -308,8 +312,8 @@ describe('store: data.js chart writes', function () {
     })
 
     it('does not alias the flow\'s message into an appended series', function () {
-        const global = fakeGlobal()
-        const node = fakeNode('chart-alias', global)
+        const global = storeGlobal()
+        const node = fakeNode('chart-alias')
         const sent = { payload: 1, _datapoint: pt(1, 1), nested: { a: 1 } }
 
         datastore.append(base, node, sent)
@@ -319,8 +323,8 @@ describe('store: data.js chart writes', function () {
     })
 
     it('mirrors an array save into the store as a whole series', function () {
-        const global = fakeGlobal()
-        const node = fakeNode('chart-2', global)
+        const global = storeGlobal()
+        const node = fakeNode('chart-2')
 
         datastore.save(base, node, [
             { payload: 1, _datapoint: pt(1, 1) },
@@ -334,8 +338,8 @@ describe('store: data.js chart writes', function () {
     })
 
     it('replaces rather than appends on a second array save', function () {
-        const global = fakeGlobal()
-        const node = fakeNode('chart-replace', global)
+        const global = storeGlobal()
+        const node = fakeNode('chart-replace')
 
         datastore.save(base, node, [{ payload: 1, _datapoint: pt(1, 1) }])
         datastore.save(base, node, [{ payload: 9, _datapoint: pt(9, 9) }])
@@ -346,8 +350,8 @@ describe('store: data.js chart writes', function () {
     })
 
     it('empties the series when saved an empty array', function () {
-        const global = fakeGlobal()
-        const node = fakeNode('chart-clear', global)
+        const global = storeGlobal()
+        const node = fakeNode('chart-clear')
 
         datastore.append(base, node, { payload: 1, _datapoint: pt(1, 1) })
         datastore.save(base, node, [])
@@ -358,8 +362,8 @@ describe('store: data.js chart writes', function () {
     })
 
     it('does not rebuild the stored series until the batch is reached', function () {
-        const global = fakeGlobal()
-        const node = fakeNode('chart-3', global)
+        const global = storeGlobal()
+        const node = fakeNode('chart-3')
         for (let i = 0; i < 100; i++) {
             datastore.append(base, node, { payload: i, _datapoint: pt(i, i) })
         }
@@ -369,13 +373,13 @@ describe('store: data.js chart writes', function () {
         }
 
         liveStore(global, 'canary-3').should.equal('live')
-        datastore.get('chart-3').should.have.length(41)
         global.get('dashboardStore')['chart-3'].should.have.length(100)
+        datastore.get('chart-3').should.have.length(41)
     })
 
     it('rebuilds the stored series on the batch boundary', function () {
-        const global = fakeGlobal()
-        const node = fakeNode('chart-batch', global)
+        const global = storeGlobal()
+        const node = fakeNode('chart-batch')
         for (let i = 0; i < 100; i++) {
             datastore.append(base, node, { payload: i, _datapoint: pt(i, i) })
         }
@@ -393,9 +397,9 @@ describe('store: data.js chart writes', function () {
     })
 
     it('does not create a key when the appended message is not an object', function () {
-        const global = fakeGlobal()
-        const node = fakeNode('chart-junk', global)
-        datastore.append(base, fakeNode('chart-ok', global), { payload: 1, _datapoint: pt(1, 1) })
+        const global = storeGlobal()
+        const node = fakeNode('chart-junk')
+        datastore.append(base, fakeNode('chart-ok'), { payload: 1, _datapoint: pt(1, 1) })
 
         datastore.append(base, node, 5)
         datastore.save(base, node, [5, { payload: 1, _datapoint: pt(1, 1) }])
@@ -405,8 +409,8 @@ describe('store: data.js chart writes', function () {
     })
 
     it('leaves the stored series untouched when trims remove nothing', function () {
-        const global = fakeGlobal()
-        const node = fakeNode('chart-noop', global)
+        const global = storeGlobal()
+        const node = fakeNode('chart-noop')
         for (let i = 0; i < 100; i++) {
             datastore.append(base, node, { payload: i, _datapoint: pt(i, i) })
         }
@@ -419,9 +423,19 @@ describe('store: data.js chart writes', function () {
         global.get('dashboardStore')['$chart-noop'].msg.should.eql(before)
     })
 
-    it('still keeps the legacy chart series intact', function () {
-        const global = fakeGlobal()
-        const node = fakeNode('chart-4', global)
+    it('ignores a filter call with no callback', function () {
+        storeGlobal()
+        const node = fakeNode('chart-nofilter')
+        datastore.append(base, node, { payload: 1, _datapoint: pt(1, 1) })
+
+        should(() => datastore.filter(base, node, undefined)).not.throw()
+
+        datastore.get('chart-nofilter').should.have.length(1)
+    })
+
+    it('keeps the trimmed chart series', function () {
+        storeGlobal()
+        const node = fakeNode('chart-4')
 
         datastore.append(base, node, { _datapoint: pt(1, 1) })
         datastore.append(base, node, { _datapoint: pt(2, 2) })
@@ -433,7 +447,7 @@ describe('store: data.js chart writes', function () {
     it('clears a stale key if a node id was previously used for a value', function () {
         const global = fakeGlobal()
         datastore.initStore(global, {})
-        const node = fakeNode('chart-5', global)
+        const node = fakeNode('chart-5')
 
         datastore.save(base, node, { payload: 'scalar first' })
         global.get('dashboardStore')['chart-5'].should.equal('scalar first')
@@ -443,8 +457,8 @@ describe('store: data.js chart writes', function () {
     })
 
     it('keeps history empty across many appends', function () {
-        const global = fakeGlobal()
-        const node = fakeNode('chart-hist', global)
+        const global = storeGlobal()
+        const node = fakeNode('chart-hist')
         for (let i = 0; i < 20; i++) {
             datastore.append(base, node, { payload: i, _datapoint: pt(i, i) })
         }
@@ -453,8 +467,8 @@ describe('store: data.js chart writes', function () {
     })
 
     it('serialises a chart key to its point array and nothing else', function () {
-        const global = fakeGlobal()
-        const node = fakeNode('chart-json', global)
+        const global = storeGlobal()
+        const node = fakeNode('chart-json')
         datastore.append(base, node, { payload: 1, topic: 'a', _datapoint: pt(1, 1) })
 
         JSON.parse(JSON.stringify(global.get('dashboardStore'))).should.eql({
@@ -462,10 +476,10 @@ describe('store: data.js chart writes', function () {
         })
     })
 
-    it('leaves the legacy series untouched when the store is disabled', function () {
+    it('leaves global context untouched when it cannot hold the store', function () {
         const global = fakeGlobal()
-        const node = fakeNode('chart-off', global)
-        datastore.disableStore()
+        const node = fakeNode('chart-off')
+        datastore.initStore({ get () { throw new Error('cache off') }, set () {} }, {})
         try {
             datastore.append(base, node, { payload: 1, _datapoint: pt(1, 1) })
             datastore.save(base, node, [{ payload: 2, _datapoint: pt(2, 2) }])
@@ -480,9 +494,13 @@ describe('store: data.js chart writes', function () {
 })
 
 describe('store: data.js audit invariants', function () {
+    beforeEach(function () {
+        datastore.initStore(fakeGlobal(), {})
+    })
+
     it('does not store a message carrying only dynamic properties', function () {
-        const global = fakeGlobal()
-        const node = fakeNode('a1', global)
+        const global = storeGlobal()
+        const node = fakeNode('a1')
         datastore.save(base, node, { payload: 'real' })
         datastore.save(base, node, { ui_update: { class: 'red' } })
 
@@ -490,8 +508,8 @@ describe('store: data.js audit invariants', function () {
     })
 
     it('keeps value and msg in step across writes', function () {
-        const global = fakeGlobal()
-        const node = fakeNode('a2', global)
+        const global = storeGlobal()
+        const node = fakeNode('a2')
         datastore.save(base, node, { payload: 1, topic: 'first' })
         datastore.save(base, node, { payload: 2, topic: 'second' })
 
@@ -501,8 +519,8 @@ describe('store: data.js audit invariants', function () {
     })
 
     it('leaves no key at all when a widget never stores', function () {
-        const global = fakeGlobal()
-        datastore.save(base, fakeNode('a3', global), { payload: 1 })
+        const global = storeGlobal()
+        datastore.save(base, fakeNode('a3'), { payload: 1 })
 
         const store = global.get('dashboardStore')
         store.a3.should.equal(1)
@@ -512,7 +530,7 @@ describe('store: data.js audit invariants', function () {
     it('clears value and msg together when a widget is removed', function () {
         const global = fakeGlobal()
         datastore.initStore(global, {})
-        const node = fakeNode('a4', global)
+        const node = fakeNode('a4')
         datastore.save(base, node, { payload: 5, topic: 't' })
         global.get('dashboardStore').$a4.msg.should.be.an.Object()
 
@@ -525,9 +543,13 @@ describe('store: data.js audit invariants', function () {
 })
 
 describe('store: data.js client-scoped writes', function () {
+    beforeEach(function () {
+        datastore.initStore(fakeGlobal(), {})
+    })
+
     describe('save', function () {
         const base = { acceptsClientConfig: ['ui-text'] }
-        const node = fakeNode('w1', fakeGlobal())
+        const node = fakeNode('w1')
 
         beforeEach(function () {
             datastore.clear(node.id)
@@ -572,6 +594,8 @@ describe('store: data.js client-scoped writes', function () {
 
 describe('store: data.js failure reporting', function () {
     const unreachable = () => { throw new Error('context store unavailable') }
+    const baseNode = { warn: (m) => warnings.push(`base: ${m}`) }
+    const SUFFIX = '. Further store failures are not reported until the next full deploy or restart.'
 
     beforeEach(function () {
         warnings.length = 0
@@ -581,111 +605,120 @@ describe('store: data.js failure reporting', function () {
         datastore.initStore(fakeGlobal(), {})
     })
 
-    it('warns once on the widget whose write failed, not once per write', function () {
+    it('warns once on the base node when the store cannot be reached, not once per call', function () {
         const global = fakeGlobal()
-        const node = fakeNode('fail-1', global)
-        datastore.initStore(global, {})
+        datastore.initStore(global, { node: baseNode })
         global.get = unreachable
 
-        datastore.save(base, node, { payload: 1 })
-        datastore.save(base, node, { payload: 2 })
-        datastore.append(base, fakeNode('fail-1-chart', global), { payload: 1, _datapoint: { category: 'a', x: 1, y: 1 } })
-        datastore.clear(node.id)
+        datastore.save(base, fakeNode('fail-1'), { payload: 1 })
+        datastore.save(base, fakeNode('fail-1'), { payload: 2 })
+        datastore.append(base, fakeNode('fail-1-chart'), { payload: 1, _datapoint: { category: 'a', x: 1, y: 1 } })
+        datastore.filter(base, fakeNode('fail-1-chart'), () => true)
+        datastore.clear('fail-1')
+        datastore.get('fail-1')
 
-        warnings.should.have.length(1)
-        warnings[0].should.equal('fail-1: Dashboard data store: a store write failed (context store unavailable), so global.dashboardStore may be out of date. Further store failures are not reported until the next full deploy or restart.')
+        warnings.should.eql([`base: Dashboard data store: saving fail-1 failed (context store unavailable)${SUFFIX}`])
     })
 
-    it('warns when an append fails', function () {
-        const global = fakeGlobal()
-        datastore.initStore(global, {})
-        global.get = unreachable
+    it('names the operation that failed', function () {
+        for (const [action, call] of [
+            ['saving', () => datastore.append(base, fakeNode('fail-a'), { payload: 1, _datapoint: { category: 'a', x: 1, y: 1 } })],
+            ['trimming', () => datastore.keepLatestPerTopic(base, fakeNode('fail-a'), 1)],
+            ['clearing', () => datastore.clear('fail-a')],
+            ['reading', () => datastore.has('fail-a')]
+        ]) {
+            const global = fakeGlobal()
+            datastore.initStore(global, { node: baseNode })
+            global.get = unreachable
+            warnings.length = 0
 
-        datastore.append(base, fakeNode('fail-a', global), { payload: 1, _datapoint: { category: 'a', x: 1, y: 1 } })
+            call()
 
-        warnings.should.have.length(1)
-        warnings[0].should.startWith('fail-a: Dashboard data store: a store write failed (context store unavailable)')
+            warnings.should.eql([`base: Dashboard data store: ${action} fail-a failed (context store unavailable)${SUFFIX}`])
+        }
     })
 
-    it('does not throw from clear when there is no base node to warn on', function () {
+    it('does not throw when there is no base node to warn on', function () {
         const global = fakeGlobal()
         datastore.initStore(global, {})
         global.get = unreachable
 
         should(() => datastore.clear('no-base')).not.throw()
-    })
-
-    it('warns on the base node when a clear fails, since a clear has no widget node', function () {
-        const global = fakeGlobal()
-        datastore.initStore(global, { node: { warn: (m) => warnings.push(`base: ${m}`) } })
-        global.get = unreachable
-
-        datastore.clear('fail-c')
-
-        warnings.should.have.length(1)
-        warnings[0].should.startWith('base: Dashboard data store: clearing the store entry for fail-c failed (context store unavailable), so global.dashboardStore may still hold its old value.')
+        should(() => datastore.save(base, fakeNode('no-base'), { payload: 1 })).not.throw()
     })
 
     it('explains a context store that stops holding the store by reference', function () {
         const m = {}
         let copying = false
         const global = { get: (k) => copying ? JSON.parse(JSON.stringify(m[k])) : m[k], set: (k, v) => { m[k] = v } }
-        datastore.initStore(global, {})
+        datastore.initStore(global, { node: baseNode })
         copying = true
 
-        datastore.save(base, fakeNode('fail-r', global), { payload: 1 })
+        datastore.save(base, fakeNode('fail-r'), { payload: 1 })
 
-        warnings.should.have.length(1)
-        warnings[0].should.startWith('fail-r: Dashboard data store: a store write failed (global context saved a copy of the store rather than the store itself, which happens with context stores that serialise values)')
+        warnings.should.eql([`base: Dashboard data store: saving fail-r failed (global context saved a copy of the store rather than the store itself, which happens with context stores that serialise values)${SUFFIX}`])
     })
 
-    it('still writes the legacy datastore when the store write fails', function () {
+    it('reads as empty when the store cannot be reached', function () {
         const global = fakeGlobal()
-        const node = fakeNode('fail-2', global)
-        datastore.initStore(global, {})
+        datastore.initStore(global, { node: baseNode })
         global.get = unreachable
 
-        datastore.save(base, node, { payload: 'kept' })
-
-        datastore.get('fail-2').payload.should.equal('kept')
+        should(datastore.get('fail-2')).be.undefined()
+        datastore.has('fail-2').should.equal(false)
     })
 
     it('warns again after the next initStore', function () {
         const global = fakeGlobal()
-        datastore.initStore(global, {})
+        datastore.initStore(global, { node: baseNode })
         global.get = unreachable
-        datastore.save(base, fakeNode('fail-3', global), { payload: 1 })
+        datastore.save(base, fakeNode('fail-3'), { payload: 1 })
 
         const fresh = fakeGlobal()
-        datastore.initStore(fresh, {})
+        datastore.initStore(fresh, { node: baseNode })
         fresh.get = unreachable
-        datastore.save(base, fakeNode('fail-3', fresh), { payload: 2 })
+        datastore.save(base, fakeNode('fail-3'), { payload: 2 })
 
         warnings.should.have.length(2)
     })
 
-    it('warns on the widget when a trim cannot reach the store', function () {
-        const global = fakeGlobal()
-        const node = fakeNode('fail-5', global)
-        datastore.initStore(global, {})
-        for (let i = 0; i < 100; i++) datastore.append(base, node, { payload: i, _datapoint: { category: 'a', x: i, y: i } })
-        global.get = unreachable
+    it('throws a failing filter to the widget without reporting a store failure', function () {
+        datastore.initStore(fakeGlobal(), { node: baseNode })
+        const node = fakeNode('fail-6')
+        datastore.append(base, node, { payload: 1, _datapoint: null })
 
-        datastore.filter(base, node, (m, idx) => idx > 0)
+        should.throws(() => datastore.filter(base, node, (m) => m._datapoint.x > 0))
 
-        warnings.should.have.length(1)
-        warnings[0].should.startWith('fail-5: ')
+        warnings.should.eql([])
     })
 
-    it('throws a failing filter to the widget without reporting a store failure', function () {
-        const global = fakeGlobal()
-        const node = fakeNode('fail-6', global)
-        datastore.initStore(global, {})
-        datastore.append(base, node, { payload: 1, _datapoint: null })
+    it('leaves the stored message untouched when a save cannot be copied', function () {
+        datastore.initStore(fakeGlobal(), { node: baseNode })
+        const node = fakeNode('fail-8')
+        datastore.save(base, node, { payload: 1, topic: 't', label: 'L' })
 
-        should.throws(() => datastore.filter(base, node, (m) => m._datapoint.x > 0))
+        should.throws(() => datastore.save(base, node, { payload: 2, meta: { get bad () { throw new Error('unreadable') } } }))
 
-        warnings.should.have.length(0)
+        datastore.get('fail-8').should.eql({ payload: 1, topic: 't', label: 'L' })
+    })
+
+    it('leaves the stored message untouched when an append cannot be copied', function () {
+        datastore.initStore(fakeGlobal(), { node: baseNode })
+        const node = fakeNode('fail-9')
+        datastore.save(base, node, { payload: 1, topic: 't' })
+
+        should.throws(() => datastore.append(base, node, { payload: 2, meta: { get bad () { throw new Error('unreadable') } }, _datapoint: { x: 1, y: 2 } }))
+
+        datastore.get('fail-9').should.eql({ payload: 1, topic: 't' })
+    })
+
+    it('throws a message the store cannot copy to the widget without reporting a store failure', function () {
+        datastore.initStore(fakeGlobal(), { node: baseNode })
+        const unreadable = { get payload () { throw new Error('unreadable') } }
+
+        should.throws(() => datastore.save(base, fakeNode('fail-7'), unreadable), /unreadable/)
+
+        warnings.should.eql([])
     })
 })
 
@@ -701,7 +734,7 @@ describe('store: data reads that avoid cloning', function () {
     const topicsAndPayloads = (id) => datastore.get(id).map((m) => `${m.topic}:${m.payload}`)
 
     beforeEach(function () {
-        datastore.disableStore()
+        datastore.initStore({ get () { throw new Error('cache off') }, set () {} }, {})
         datastore.setConfig(countingRED)
     })
 
@@ -803,7 +836,7 @@ describe('store: data.js merges into the store from the store itself', function
     it('stores a message without a payload, merged onto the stored one', function () {
         const global = fakeGlobal()
         datastore.initStore(global, {})
-        const node = fakeNode('merge-1', global)
+        const node = fakeNode('merge-1')
 
         datastore.save(base, node, { payload: 1 })
         datastore.save(base, node, { topic: 't' })
@@ -814,21 +847,21 @@ describe('store: data.js merges into the store from the store itself', function
     it('merges onto what the store holds, not what the legacy datastore holds', function () {
         const global = fakeGlobal()
         datastore.initStore(global, {})
-        const node = fakeNode('merge-2', global)
+        const node = fakeNode('merge-2')
         datastore.save(base, node, { payload: 1 })
         global.get('dashboardStore')['merge-2'] = 5
 
         datastore.save(base, node, { topic: 't' })
 
         global.get('dashboardStore')['$merge-2'].msg.should.eql({ payload: 5, topic: 't' })
-        datastore.get('merge-2').should.eql({ payload: 1, topic: 't' })
+        datastore.get('merge-2').should.eql({ payload: 5, topic: 't' })
     })
 
     it('ignores a message that is not an object, without warning', function () {
         const global = fakeGlobal()
         datastore.initStore(global, {})
         const warned = []
-        const node = { ...fakeNode('merge-4', global), warn: (m) => warned.push(m) }
+        const node = { ...fakeNode('merge-4'), warn: (m) => warned.push(m) }
         datastore.save(base, node, { payload: 1 })
 
         datastore.save(base, node, 5)
@@ -840,7 +873,7 @@ describe('store: data.js merges into the store from the store itself', function
     it('removes the store entry on clear(id), which has no node', function () {
         const global = fakeGlobal()
         datastore.initStore(global, {})
-        datastore.save(base, fakeNode('merge-3', global), { payload: 'hello' })
+        datastore.save(base, fakeNode('merge-3'), { payload: 'hello' })
 
         datastore.clear('merge-3')
 
@@ -858,7 +891,7 @@ describe('store: data.js trims the stored series itself', function () {
     it('trims what the store holds, not a copy of the legacy result', function () {
         const global = fakeGlobal()
         datastore.initStore(global, {})
-        const node = fakeNode('own-trim', global)
+        const node = fakeNode('own-trim')
         datastore.save(base, node, [])
         for (let i = 0; i < 6; i++) {
             datastore.append(base, node, point(i, i % 2 ? 'b' : 'a'))
@@ -868,13 +901,13 @@ describe('store: data.js trims the stored series itself', function () {
         datastore.keepLatestPerTopic(base, node, 2)
 
         global.get('dashboardStore')['$own-trim'].msg.map((m) => m.payload).should.eql([3, 4, 5, 'store-only'])
-        datastore.get('own-trim').map((m) => m.payload).should.eql([2, 3, 4, 5])
+        datastore.get('own-trim').map((m) => m.payload).should.eql([3, 4, 5, 'store-only'])
     })
 
     it('applies both a point limit and a time window', function () {
         const global = fakeGlobal()
         datastore.initStore(global, {})
-        const node = fakeNode('both-limits', global)
+        const node = fakeNode('both-limits')
         datastore.save(base, node, [])
         for (let i = 0; i < 100; i++) {
             datastore.append(base, node, point(i))
@@ -885,3 +918,32 @@ describe('store: data.js trims the stored series itself', function () {
         global.get('dashboardStore')['$both-limits'].msg.map((m) => m.payload).should.eql(datastore.get('both-limits').map((m) => m.payload))
     })
 })
+
+describe('store: data.js after a restart with a persistent context store', function () {
+    const restored = (values) => {
+        const global = fakeGlobal()
+        global.set('dashboardStore', JSON.parse(JSON.stringify(values)))
+        datastore.initStore(global, {})
+    }
+
+    afterEach(function () {
+        datastore.initStore(fakeGlobal(), {})
+    })
+
+    it('starts empty, as main does', function () {
+        restored({ text: 'hello', rows: [{ id: 1 }], chart: [{ category: 'a', x: 1, y: 1 }] })
+
+        datastore.has('text').should.equal(false)
+        should(datastore.get('text')).be.undefined()
+        datastore.has('rows').should.equal(false)
+        datastore.has('chart').should.equal(false)
+    })
+
+    it('stores a chart\'s first point after a restart as a fresh series', function () {
+        restored({ chart: [{ category: 'a', x: 1, y: 1 }] })
+
+        datastore.append(base, fakeNode('chart'), { payload: 2, _datapoint: { category: 'a', x: 2, y: 2 } })
+
+        datastore.get('chart').should.eql([{ payload: 2, _datapoint: { category: 'a', x: 2, y: 2 } }])
+    })
+})
diff --git a/test/store/differential.spec.js b/test/store/differential.spec.js
index 6ec849eab..cd540769f 100644
--- a/test/store/differential.spec.js
+++ b/test/store/differential.spec.js
@@ -14,6 +14,10 @@ function fakeGlobal () {
     return { get: (k) => m[k], set: (k, v) => { m[k] = v } }
 }
 
+function cacheOffGlobal () {
+    return { get () { throw new Error('File Store cache disabled - only asynchronous access supported') }, set () {} }
+}
+
 const runs = [
     ...Object.entries(scenarios).map(([name, steps]) => ({ name, steps })),
     ...Array.from({ length: 200 }, (_, i) => ({ name: `seed ${i + 1}`, steps: generate(i + 1, 180) })),
@@ -50,14 +54,17 @@ function storeHolds (global, id) {
     return store['$' + id]?.msg
 }
 
-function compareAfterEachStep (steps, ids) {
-    const global = fakeGlobal()
+function compareAfterEachStep (steps, ids, global = fakeGlobal()) {
     const warnings = []
-    datastore.initStore(global, {})
+    const baseNode = { warn: (m) => warnings.push(m) }
+    const shared = datastore.initStore(global, { node: baseNode })
     const nodeFor = (id, type) => ({ id, type, context: () => ({ global }), warn: (m) => warnings.push(m) })
     const legacy = createLegacy(RED)
     let comparedWithData = 0
-    for (const step of steps) {
+    for (const [i, step] of steps.entries()) {
+        if (i === Math.floor(steps.length / 2)) {
+            datastore.initStore(global, { node: baseNode })
+        }
         const given = structuredClone(step)
         runStep(datastore, given, { base, nodeFor })
         runStep(legacy, structuredClone(step), { base, nodeFor })
@@ -67,22 +74,26 @@ function compareAfterEachStep (steps, ids) {
         scribble(datastore.get(step.id))
         should(datastore.get(step.id)).eql(legacy.get(step.id), `${step.id} after scribbling what get returned`)
         datastore.has(step.id).should.equal(legacy.has(step.id), `${step.id} after ${step.op}`)
-        should(storeHolds(global, step.id)).eql(legacy.get(step.id), `store for ${step.id} after ${step.op}`)
+        if (shared) {
+            should(storeHolds(global, step.id)).eql(legacy.get(step.id), `store for ${step.id} after ${step.op}`)
+        }
         if (legacy.has(step.id)) {
             comparedWithData++
         }
     }
     for (const id of ids) {
         should(datastore.get(id)).eql(legacy.get(id), id)
-        should(storeHolds(global, id)).eql(legacy.get(id), `store for ${id}`)
+        if (shared) {
+            should(storeHolds(global, id)).eql(legacy.get(id), `store for ${id}`)
+        }
     }
-    return { comparedWithData, warnings }
+    return { comparedWithData, warnings, shared }
 }
 
 function compareAtEnd (steps, ids) {
     const global = fakeGlobal()
     const warnings = []
-    datastore.initStore(global, {})
+    datastore.initStore(global, { node: { warn: (m) => warnings.push(m) } })
     const nodeFor = (id, type) => ({ id, type, context: () => ({ global }), warn: (m) => warnings.push(m) })
     const legacy = createLegacy(RED)
     for (const step of steps) {
@@ -109,8 +120,22 @@ describe('store: differential against the legacy datastore', function () {
         for (const run of runs) {
             it(run.name, function () {
                 const { steps, ids } = prepare(run.steps)
-                const { comparedWithData, warnings } = compareAfterEachStep(steps, ids)
+                const { comparedWithData, warnings, shared } = compareAfterEachStep(steps, ids)
+
+                should(shared).not.be.null()
+                comparedWithData.should.be.above(0)
+                warnings.should.eql([])
+            })
+        }
+    })
+
+    describe('data.js matches the legacy reference when global context cannot hold the store', function () {
+        for (const run of runs) {
+            it(run.name, function () {
+                const { steps, ids } = prepare(run.steps)
+                const { comparedWithData, warnings, shared } = compareAfterEachStep(steps, ids, cacheOffGlobal())
 
+                should(shared).be.null()
                 comparedWithData.should.be.above(0)
                 warnings.should.eql([])
             })
diff --git a/test/store/reactive.spec.js b/test/store/reactive.spec.js
index 703c57ba5..64c5d67b0 100644
--- a/test/store/reactive.spec.js
+++ b/test/store/reactive.spec.js
@@ -11,7 +11,7 @@ const Memory = require('@node-red/runtime/lib/nodes/context/memory.js')
 const { util } = require('@node-red/util')
 const should = require('should') // eslint-disable-line no-unused-vars
 
-const { createDataStore, attachToContext, STORE, APPEND_ENTRY, SET_SERIES, MERGE_ENTRY, TRIM_SERIES } = require('../../nodes/store/reactive.js')
+const { createDataStore, attachToContext, STORE, APPEND_ENTRY, SET_SERIES, MERGE_ENTRY, TRIM_SERIES, ENTRY_MSG } = require('../../nodes/store/reactive.js')
 
 function makeStore (opts = {}) {
     const log = []
@@ -963,9 +963,11 @@ describe('store: reactive data store', function () {
     })
 
     describe('attachToContext', function () {
-        it('does not rehydrate an array into numeric keys', function () {
-            const m = { dashboardStore: ['a', 'b'] }
+        it('does not copy an array a flow put in its place into numeric keys', function () {
+            const m = {}
             const g = { get: (k) => m[k], set: (k, v) => { m[k] = v } }
+            attachToContext(g, {})
+            m.dashboardStore = ['a', 'b']
 
             const store = attachToContext(g, {})
 
@@ -973,18 +975,22 @@ describe('store: reactive data store', function () {
             JSON.stringify(store).should.equal('{}')
         })
 
-        it('does not spread a class instance into keys', function () {
-            const m = { dashboardStore: new Date() }
+        it('does not spread a class instance a flow put in its place into keys', function () {
+            const m = {}
             const g = { get: (k) => m[k], set: (k, v) => { m[k] = v } }
+            attachToContext(g, {})
+            m.dashboardStore = new Date()
 
             const store = attachToContext(g, {})
 
             Object.keys(store).should.eql([])
         })
 
-        it('rehydrates an object a function node left at the namespace', function () {
-            const m = { dashboardStore: fnNodeObject('({ robot: "PLAIN", count: 3 })') }
+        it('copies in an object a function node put in its place', function () {
+            const m = {}
             const g = { get: (k) => m[k], set: (k, v) => { m[k] = v } }
+            attachToContext(g, {})
+            m.dashboardStore = fnNodeObject('({ robot: "PLAIN", count: 3 })')
 
             const store = attachToContext(g, {})
 
@@ -992,9 +998,11 @@ describe('store: reactive data store', function () {
             store.count.should.equal(3)
         })
 
-        it('still rehydrates a plain object', function () {
-            const m = { dashboardStore: { robot: { temp: 20 }, count: 3 } }
+        it('copies in a plain object a flow put in its place', function () {
+            const m = {}
             const g = { get: (k) => m[k], set: (k, v) => { m[k] = v } }
+            attachToContext(g, {})
+            m.dashboardStore = { robot: { temp: 20 }, count: 3 }
 
             const store = attachToContext(g, {})
 
@@ -1036,8 +1044,9 @@ describe('store: reactive data store', function () {
             should(second).equal(first)
         })
 
-        it('rehydrates around existing plain data and rewires reactivity', function () {
+        it('rewires reactivity around plain data a flow put in its place', function () {
             const g = fakeGlobal()
+            attachToContext(g)
             g.set('dashboardStore', { a: 5, robot: { temp: 1 } })
             const log = []
             const store = attachToContext(g, { onChange: (k, e, p) => log.push(p) })
@@ -1086,13 +1095,14 @@ describe('store: reactive data store', function () {
             warned.should.equal(0)
         })
 
-        it('does not warn when a restart rehydrates plain data it never injected', function () {
+        it('starts fresh after a restart, without warning, rather than restoring plain data it never injected', function () {
             const g = fakeGlobal()
             g.set('dashboardStore', { widget: 'from disk' }) // what a persistent context store hands back
             let warned = 0
             const store = attachToContext(g, { onReplaced: () => { warned++ } })
             warned.should.equal(0)
-            store.widget.should.equal('from disk')
+            should(store.widget).be.undefined()
+            should(g.get('dashboardStore')).equal(store)
         })
 
         const replacements = [
@@ -1348,6 +1358,49 @@ describe('store: MERGE_ENTRY', function () {
     })
 })
 
+describe('store: ENTRY_MSG', function () {
+    const point = (x) => ({ payload: x, topic: 'a', _datapoint: { category: 'a', x, y: x } })
+
+    it('reads a stored message without building a new object', function () {
+        const { store } = makeStore({ clone: util.cloneMessage })
+        store[MERGE_ENTRY]('k', { payload: 1, topic: 't' })
+        store[MERGE_ENTRY]('k', { payload: 2 })
+
+        store[ENTRY_MSG]('k').should.equal(store[ENTRY_MSG]('k'))
+        store[ENTRY_MSG]('k').should.eql({ payload: 2, topic: 't' })
+    })
+
+    it('reads a series with pending trims applied, as a frozen copy', function () {
+        const { store } = makeStore({ clone: util.cloneMessage })
+        for (let x = 0; x < 5; x++) {
+            store[APPEND_ENTRY]('c', point(x))
+        }
+        store[TRIM_SERIES]('c', (msgs) => msgs.filter((m) => m.payload > 2))
+
+        const msgs = store[ENTRY_MSG]('c')
+
+        msgs.map((m) => m.payload).should.eql([3, 4])
+        Object.isFrozen(msgs).should.equal(true)
+        store[ENTRY_MSG]('c').should.not.equal(msgs)
+    })
+
+    it('matches the $ view', function () {
+        const { store } = makeStore({ clone: util.cloneMessage })
+        store[APPEND_ENTRY]('c', point(1))
+        store[TRIM_SERIES]('c', (msgs) => msgs)
+        store[MERGE_ENTRY]('k', { payload: 1 })
+
+        store[ENTRY_MSG]('c').should.eql(store.$c.msg)
+        store[ENTRY_MSG]('k').should.equal(store.$k.msg)
+    })
+
+    it('reads nothing for a missing entry', function () {
+        const { store } = makeStore({ clone: util.cloneMessage })
+
+        should(store[ENTRY_MSG]('missing')).be.undefined()
+    })
+})
+
 describe('store: TRIM_SERIES', function () {
     const point = (x, topic = 'a') => ({ payload: x, topic, _datapoint: { category: topic, x, y: x } })
     const keepLatest = (max) => (msgs) => msgs.filter((m, i) => msgs.slice(i + 1).filter((n) => n.topic === m.topic).length < max)