From 46d945935c7614b2e8364e954d78822dc213ac72 Mon Sep 17 00:00:00 2001
From: pdelfan <pdelfan@gmail.com>
Date: Fri, 16 Oct 2026 22:22:14 -0700
Subject: [PATCH] The web app's message records are typed as the lexicon's
 MessageRecord, and a conversation's info as InfoRecord, from the local copy,
 which holds only records the server validated, through BranchMessage to the
 message, status, details, part, and tool views, so their reads need no casts.
 src/shared/message.ts holds what a status means, isPending and isFinished,
 which counts a status another client wrote that this app doesn't know as
 neither, along with a message's parts, whether it is encrypted, and who wrote
 it, in place of the checks written out in the message view, the message
 actions, the chat, the reply follower, and tool status. Tests build records
 with messageRecord in tests/helpers/records.ts, and the status rules are
 tested once.

---
 CHANGELOG.md                                  |  1 +
 apps/web/src/features/conversation/chat.ts    |  3 +-
 .../components/BranchComposer.tsx             |  2 +-
 .../components/ConversationView.tsx           | 10 +-
 .../conversation/components/MessageView.tsx   | 39 ++++----
 .../conversation/components/PartsView.tsx     |  5 +-
 .../conversation/components/PendingReply.tsx  |  7 +-
 .../conversation/components/RecordDetails.tsx | 22 ++---
 .../conversation/components/Status.tsx        |  7 +-
 .../components/message-actions.tsx            | 12 +--
 .../src/features/conversation/lib/branch.ts   | 14 ++-
 .../features/conversation/reply-follower.ts   | 11 +--
 .../src/features/sharing/pages/SharedPage.tsx |  3 +-
 apps/web/src/parts/WorkSteps.tsx              | 17 ++--
 apps/web/src/parts/tool-status.ts             |  5 +-
 apps/web/src/parts/types.ts                   |  5 +-
 apps/web/src/shared/message.ts                | 30 ++++++
 apps/web/src/store/core.ts                    | 10 +-
 .../tests/features/conversation/chat.test.tsx |  9 +-
 .../components/MessageView.test.tsx           | 98 ++++++++++---------
 .../components/RecordDetails.test.tsx         |  6 +-
 .../features/conversation/lib/branch.test.ts  |  7 +-
 .../features/conversation/lib/outline.test.ts |  5 +-
 .../conversation/reply-follower.test.tsx      |  5 +-
 apps/web/tests/helpers/records.ts             | 16 +++
 apps/web/tests/shared/message.test.ts         | 35 +++++++
 specs/extending.md                            |  2 +-
 27 files changed, 244 insertions(+), 142 deletions(-)
 create mode 100644 apps/web/src/shared/message.ts
 create mode 100644 apps/web/tests/helpers/records.ts
 create mode 100644 apps/web/tests/shared/message.test.ts

diff --git a/CHANGELOG.md b/CHANGELOG.md
index 2382ab4..859426b 100644
--- a/CHANGELOG.md
+++ b/CHANGELOG.md
@@ -8,6 +8,7 @@ What changed in each release of SCN Chat, for the people who use it, run it, or
 
 - For forkers: a tab reaches the browser store through `StoreClient.calls`, which has every method of the store's logic, rather than `StoreClient.worker`. Web tests run components over the real store through `testStore` in `apps/web/tests/helpers/store.ts`, rather than hand-built fakes.
 - For forkers: a pending reply is drawn by `PendingReply.tsx` in the conversation feature, which `MessageView` uses while a record is pending, and which follows the conversation `FollowedConversation` names. `MessageView` and `BranchView` no longer take `pending` and `live` slots, and `LiveAuthor.tsx`, `ReplyStream.tsx`, and `StreamingReply.tsx` are gone.
+- For forkers: the web app's message records are typed as the lexicon's `MessageRecord`, from the local copy through `BranchMessage` to the part and tool views, and `src/shared/message.ts` holds what a status means (`isPending`, `isFinished`), a message's parts, and who wrote it.
 
 ## [0.2.1] - 2026-10-16
 
diff --git a/apps/web/src/features/conversation/chat.ts b/apps/web/src/features/conversation/chat.ts
index cc76bd7..93a5f12 100644
--- a/apps/web/src/features/conversation/chat.ts
+++ b/apps/web/src/features/conversation/chat.ts
@@ -2,6 +2,7 @@ import type { ModelRef } from '@scn-chat/lexicons'
 import { useMutation } from '@tanstack/react-query'
 import { useRef } from 'react'
 import { api, json, read } from '../../shared/api.ts'
+import { isPending } from '../../shared/message.ts'
 import { useConversation, useRefreshConversation } from '../../store/react.tsx'
 import { useBranch } from './hooks/useBranch.ts'
 import { useReplyFollower } from './reply-follower.ts'
@@ -114,7 +115,7 @@ export function useChat(skey: string, options: ChatOptions = {}) {
     /** Why the conversation couldn't be read, if it couldn't. */
     loadError: error,
     /** The reply running at the end of the branch, by key, if one is. */
-    running: leaf?.record.status === 'pending' ? leaf.rkey : null,
+    running: leaf && isPending(leaf.record) ? leaf.rkey : null,
     send,
     /** Ask again for the reply to a user message, by its key, with a model or the same one. */
     regenerate: (parent: string | null, model: ModelRef | null) => regenerate({ parent, model }),
diff --git a/apps/web/src/features/conversation/components/BranchComposer.tsx b/apps/web/src/features/conversation/components/BranchComposer.tsx
index fec0244..f4064ce 100644
--- a/apps/web/src/features/conversation/components/BranchComposer.tsx
+++ b/apps/web/src/features/conversation/components/BranchComposer.tsx
@@ -26,7 +26,7 @@ interface Props {
 // The ref is kept out of `props`, as in the composer, so React Compiler still memoizes this.
 export function BranchComposer({ ref, ...props }: Props) {
   if (props.editing) {
-    const parent = props.editing.record.parent as string | undefined
+    const parent = props.editing.record.parent
     return (
       <Composer
         // Editing another message starts the composer over from that message.
diff --git a/apps/web/src/features/conversation/components/ConversationView.tsx b/apps/web/src/features/conversation/components/ConversationView.tsx
index 81ffbb5..34e2630 100644
--- a/apps/web/src/features/conversation/components/ConversationView.tsx
+++ b/apps/web/src/features/conversation/components/ConversationView.tsx
@@ -42,7 +42,7 @@ export function ConversationView(props: Props) {
   const [editingRkey, setEditingRkey] = useState<string | null>(null)
   // Every chat has an info record from its creation, so until it arrives, from the local copy or
   // the PDS, the chat's title and instructions are unknown rather than empty.
-  const title = waiting && !info ? undefined : ((info?.title as string | undefined) ?? 'New chat')
+  const title = waiting && !info ? undefined : (info?.title ?? 'New chat')
   useDocumentTitle(title)
   // The messages there when the chat first loaded, which show at once. Only later ones fade in.
   const [opened, setOpened] = useState<Set<string> | null>(null)
@@ -81,7 +81,7 @@ export function ConversationView(props: Props) {
       <ConversationHeader
         skey={props.skey}
         title={title}
-        instructions={info ? ((info.systemPrompt as string | undefined) ?? '') : undefined}
+        instructions={info ? (info.systemPrompt ?? '') : undefined}
         outline={() => outlineOf(branch)}
         onRename={actions.rename}
         onSetInstructions={actions.setInstructions}
@@ -100,11 +100,7 @@ export function ConversationView(props: Props) {
               actions={(message) => <MessageActions message={message} operations={operations} />}
               // A failed reply tries again with the same model.
               retry={(message) => (
-                <TryAgain
-                  onClick={() =>
-                    regenerate((message.record.parent as string | undefined) ?? null, null)
-                  }
-                />
+                <TryAgain onClick={() => regenerate(message.record.parent ?? null, null)} />
               )}
               arrived={(message) => !opened?.has(message.rkey)}
             />
diff --git a/apps/web/src/features/conversation/components/MessageView.tsx b/apps/web/src/features/conversation/components/MessageView.tsx
index 356f498..caf9860 100644
--- a/apps/web/src/features/conversation/components/MessageView.tsx
+++ b/apps/web/src/features/conversation/components/MessageView.tsx
@@ -1,8 +1,15 @@
 import { type ReactNode, useId, useState } from 'react'
 import { stepsOf } from '../../../parts/steps.ts'
-import type { BlobUrl, Part } from '../../../parts/types.ts'
+import type { BlobUrl } from '../../../parts/types.ts'
 import { WorkButton, WorkList } from '../../../parts/WorkSteps.tsx'
 import { cn } from '../../../shared/cn.ts'
+import {
+  authorOf,
+  isEncrypted,
+  isPending,
+  type MessageRecord,
+  partsOf,
+} from '../../../shared/message.ts'
 import { PartsView } from './PartsView.tsx'
 import { PendingAuthor, PendingBody } from './PendingReply.tsx'
 import { SiblingPicker, type Siblings } from './SiblingPicker.tsx'
@@ -12,7 +19,7 @@ export interface MessageViewProps {
   id?: string
   /** The message's record key, which its steps' times are kept by. */
   rkey?: string
-  record: Record<string, unknown>
+  record: MessageRecord
   blobUrl: BlobUrl
   siblings?: Siblings
   actions?: ReactNode
@@ -22,24 +29,20 @@ export interface MessageViewProps {
   arrived?: boolean
 }
 
-type ModelRef = { provider: string; id: string }
-
-/** Who wrote a message: the user, or the model that wrote the reply. */
-function author(record: Record<string, unknown>): string {
-  if (record.role === 'user') return 'You'
-  return (record.model as ModelRef | undefined)?.id ?? 'Assistant'
-}
-
 interface AuthorProps {
   rkey?: string
-  record: Record<string, unknown>
+  record: MessageRecord
 }
 
 /** Who wrote the message, or for a pending reply, its live status. */
 function Author(props: AuthorProps) {
-  if (props.record.status !== 'pending') return <strong>{author(props.record)}</strong>
+  if (!isPending(props.record)) return <strong>{authorOf(props.record)}</strong>
   return (
-    <PendingAuthor rkey={props.rkey} model={author(props.record)} since={props.record.createdAt} />
+    <PendingAuthor
+      rkey={props.rkey}
+      model={authorOf(props.record)}
+      since={props.record.createdAt}
+    />
   )
 }
 
@@ -51,11 +54,9 @@ function Author(props: AuthorProps) {
  */
 export function MessageView(props: MessageViewProps) {
   const record = props.record
-  const content = record.content as { $type: string; parts?: Part[] }
-  const parts = content.parts ?? []
-  const encrypted = content.$type.endsWith('#encryptedContent')
+  const parts = partsOf(record)
   // A pending reply shows its stream until its finished record replaces it.
-  const pending = record.status === 'pending'
+  const pending = isPending(record)
   const steps = pending ? [] : stepsOf(parts)
   const user = record.role === 'user'
   const workId = useId()
@@ -64,7 +65,7 @@ export function MessageView(props: MessageViewProps) {
     <article
       id={props.id}
       data-role={user ? 'user' : 'assistant'}
-      data-status={(record.status as string | undefined) ?? undefined}
+      data-status={record.status}
       data-arrived={props.arrived || undefined}
       className={cn(
         'group/message mt-within first-of-type:mt-5.5 data-arrived:animate-fade-in motion-reduce:animate-none',
@@ -91,7 +92,7 @@ export function MessageView(props: MessageViewProps) {
       </header>
       <PartsView parts={parts} record={record} blobUrl={props.blobUrl} scope={props.rkey} />
       {pending && <PendingBody rkey={props.rkey} record={record} blobUrl={props.blobUrl} />}
-      {encrypted && <p>This message is encrypted.</p>}
+      {isEncrypted(record) && <p>This message is encrypted.</p>}
       <Status record={record} retry={props.retry} />
       {/* The actions sit by the message's edge, a reply's at the start and the user's at the end,
           and a reply's steps button comes after them. They stay quiet until the message is
diff --git a/apps/web/src/features/conversation/components/PartsView.tsx b/apps/web/src/features/conversation/components/PartsView.tsx
index 84ffeb2..86eb3b0 100644
--- a/apps/web/src/features/conversation/components/PartsView.tsx
+++ b/apps/web/src/features/conversation/components/PartsView.tsx
@@ -2,12 +2,13 @@ import { StepsView, viewFor } from '../../../parts/index.ts'
 import { type Block, groupParts } from '../../../parts/steps.ts'
 import { type BlobUrl, kind, type Part } from '../../../parts/types.ts'
 import { ChevronDownIcon, LinkIcon } from '../../../shared/icons.tsx'
+import type { MessageRecord } from '../../../shared/message.ts'
 import { plural } from '../../../shared/plural.ts'
 
 interface Props {
   parts: Part[]
   /** The message the parts belong to, which each part's view gets. */
-  record: Record<string, unknown>
+  record: MessageRecord
   /** Whether the reply is still streaming, so its last block of steps is still going. */
   live?: boolean
   blobUrl: BlobUrl
@@ -98,7 +99,7 @@ export function PartsView(props: Props) {
 
 interface SourcesProps {
   sources: Part[]
-  record: Record<string, unknown>
+  record: MessageRecord
   blobUrl: BlobUrl
 }
 
diff --git a/apps/web/src/features/conversation/components/PendingReply.tsx b/apps/web/src/features/conversation/components/PendingReply.tsx
index b786a19..a287a9c 100644
--- a/apps/web/src/features/conversation/components/PendingReply.tsx
+++ b/apps/web/src/features/conversation/components/PendingReply.tsx
@@ -1,6 +1,7 @@
 import { createContext, useContext, useEffect, useState } from 'react'
 import { formatSeconds } from '../../../parts/step-clock.ts'
 import type { BlobUrl } from '../../../parts/types.ts'
+import type { MessageRecord } from '../../../shared/message.ts'
 import { parseDate } from '../../../shared/time.ts'
 import type { ReplyParts } from '../lib/reply-stream.ts'
 import { useFollowedReply, useReplyStarted } from '../reply-follower.ts'
@@ -92,7 +93,7 @@ function LiveAuthor(props: LiveAuthorProps) {
 interface BodyProps {
   rkey?: string
   /** The pending record, which the part views read as the stream's. */
-  record: Record<string, unknown>
+  record: MessageRecord
   blobUrl: BlobUrl
 }
 
@@ -111,7 +112,7 @@ export function PendingBody(props: BodyProps) {
 interface StreamProps {
   skey: string
   rkey: string
-  record: Record<string, unknown>
+  record: MessageRecord
   blobUrl: BlobUrl
 }
 
@@ -139,7 +140,7 @@ function ReplyStream(props: StreamProps) {
 
 interface StreamingReplyProps {
   reply: ReplyParts
-  record: Record<string, unknown>
+  record: MessageRecord
   blobUrl: BlobUrl
   /** The reply's key, so its steps' times carry over to the finished record. */
   rkey?: string
diff --git a/apps/web/src/features/conversation/components/RecordDetails.tsx b/apps/web/src/features/conversation/components/RecordDetails.tsx
index 98b2999..cee4523 100644
--- a/apps/web/src/features/conversation/components/RecordDetails.tsx
+++ b/apps/web/src/features/conversation/components/RecordDetails.tsx
@@ -1,15 +1,14 @@
-import type { ModelRef } from '@scn-chat/lexicons'
+import type { Usage } from '@scn-chat/lexicons'
 import { useId, useRef, useState } from 'react'
 import { createPortal } from 'react-dom'
 import { cn } from '../../../shared/cn.ts'
 import { InfoIcon } from '../../../shared/icons.tsx'
+import type { MessageRecord } from '../../../shared/message.ts'
 import { iconAction } from '../../../shared/ui/actions.ts'
 import { floating } from '../../../shared/ui/menu.ts'
 import { useDismiss } from '../../../shared/useDismiss.ts'
 import { usePlacement } from '../../../shared/usePlacement.ts'
 
-type Usage = { inputTokens?: number; outputTokens?: number; reasoningTokens?: number }
-
 const count = (n: number) => n.toLocaleString()
 
 function usageLine(usage: Usage): string | null {
@@ -24,7 +23,7 @@ function usageLine(usage: Usage): string | null {
 interface RecordRowsProps {
   /** The message's record key. */
   rkey?: string
-  record: Record<string, unknown>
+  record: MessageRecord
   /** Where the record lives, such as the user's PDS. */
   storedIn?: string
 }
@@ -35,19 +34,16 @@ interface RecordRowsProps {
  */
 export function recordRows(props: RecordRowsProps): [string, string][] {
   const record = props.record
-  const model = (record.model ?? (record.generation as { model?: ModelRef } | undefined)?.model) as
-    | ModelRef
-    | undefined
-  const effort = record.effort ?? (record.generation as { effort?: string } | undefined)?.effort
-  const usage = record.usage ? usageLine(record.usage as Usage) : null
+  const model = record.model ?? record.generation?.model
+  const effort = record.effort ?? record.generation?.effort
+  const usage = record.usage ? usageLine(record.usage) : null
   const rows: [string, string][] = []
   if (model)
     rows.push([record.role === 'user' ? 'Asked for' : 'Model', `${model.provider} / ${model.id}`])
-  if (effort) rows.push(['Effort', String(effort)])
+  if (effort) rows.push(['Effort', effort])
   if (usage) rows.push(['Tokens', usage])
-  if (record.status) rows.push(['Status', String(record.status)])
-  if (record.createdAt)
-    rows.push(['Written', new Date(record.createdAt as string).toLocaleString()])
+  if (record.status) rows.push(['Status', record.status])
+  if (record.createdAt) rows.push(['Written', new Date(record.createdAt).toLocaleString()])
   if (props.rkey) rows.push(['Record key', props.rkey])
   if (props.storedIn) rows.push(['Stored in', props.storedIn])
   return rows
diff --git a/apps/web/src/features/conversation/components/Status.tsx b/apps/web/src/features/conversation/components/Status.tsx
index 67d8742..bef3607 100644
--- a/apps/web/src/features/conversation/components/Status.tsx
+++ b/apps/web/src/features/conversation/components/Status.tsx
@@ -1,5 +1,6 @@
 import type { ReactNode } from 'react'
 import { AlertIcon, StopIcon } from '../../../shared/icons.tsx'
+import type { MessageRecord } from '../../../shared/message.ts'
 import { Badge } from '../../../shared/ui/Badge.tsx'
 
 /**
@@ -10,7 +11,7 @@ export const statusLine =
   'animate-breathe font-medium text-muted text-ui motion-reduce:animate-none'
 
 interface Props {
-  record: Record<string, unknown>
+  record: MessageRecord
   /** What a failed reply offers beside its error, such as a button to try again. */
   retry?: ReactNode
 }
@@ -26,9 +27,9 @@ export function Status(props: Props) {
           <AlertIcon className="mt-0.5" />
           <div className="min-w-0 flex-1">
             <strong className="font-medium">The reply failed</strong>
-            {Boolean(props.record.error) && (
+            {props.record.error && (
               <p className="mt-0.5 text-danger-muted [overflow-wrap:anywhere]">
-                {props.record.error as string}
+                {props.record.error}
               </p>
             )}
             {props.retry}
diff --git a/apps/web/src/features/conversation/components/message-actions.tsx b/apps/web/src/features/conversation/components/message-actions.tsx
index d8164c3..59a0350 100644
--- a/apps/web/src/features/conversation/components/message-actions.tsx
+++ b/apps/web/src/features/conversation/components/message-actions.tsx
@@ -1,6 +1,7 @@
 import type { ModelRef } from '@scn-chat/lexicons'
 import { type ComponentType, createContext, useContext } from 'react'
 import { PencilIcon, RetryIcon } from '../../../shared/icons.tsx'
+import { isPending } from '../../../shared/message.ts'
 import { action, iconAction } from '../../../shared/ui/actions.ts'
 import { CopyButton } from '../../../shared/ui/CopyButton.tsx'
 import { messageText } from '../../../store/core.ts'
@@ -44,8 +45,7 @@ export interface MessageAction {
 }
 
 const isUser = (message: BranchMessage) => message.record.role === 'user'
-const isPending = (message: BranchMessage) => message.record.status === 'pending'
-const parentOf = (message: BranchMessage) => (message.record.parent as string | undefined) ?? null
+const parentOf = (message: BranchMessage) => message.record.parent ?? null
 const rowsOf = (props: MessageActionProps) =>
   recordRows({
     rkey: props.message.rkey,
@@ -69,13 +69,13 @@ function EditAction(props: MessageActionProps) {
 }
 
 function CopyAction(props: MessageActionProps) {
-  if (isPending(props.message)) return null
+  if (isPending(props.message.record)) return null
   return <CopyButton text={messageText(props.message.record)} icon className={iconAction} />
 }
 
 /** Regenerate a finished reply with the same model. */
 function RegenerateAction(props: MessageActionProps) {
-  if (isUser(props.message) || isPending(props.message)) return null
+  if (isUser(props.message) || isPending(props.message.record)) return null
   return (
     <button
       type="button"
@@ -91,7 +91,7 @@ function RegenerateAction(props: MessageActionProps) {
 
 function StopAction(props: MessageActionProps) {
   const running = useContext(RunningReply)
-  if (isUser(props.message) || !isPending(props.message)) return null
+  if (isUser(props.message) || !isPending(props.message.record)) return null
   if (props.message.rkey === running) return null
   return (
     <button
@@ -112,7 +112,7 @@ function DetailsAction(props: MessageActionProps) {
 
 /** A finished reply's quote, regenerate with another model, and details. */
 function MoreAction(props: MessageActionProps) {
-  if (isUser(props.message) || isPending(props.message)) return null
+  if (isUser(props.message) || isPending(props.message.record)) return null
   return (
     <MoreActions
       elementId={`m-${props.message.rkey}`}
diff --git a/apps/web/src/features/conversation/lib/branch.ts b/apps/web/src/features/conversation/lib/branch.ts
index 9adb63c..25637b2 100644
--- a/apps/web/src/features/conversation/lib/branch.ts
+++ b/apps/web/src/features/conversation/lib/branch.ts
@@ -1,6 +1,7 @@
 import type { ModelRef } from '@scn-chat/lexicons'
+import type { MessageRecord } from '../../../shared/message.ts'
 
-export type BranchMessage = { rkey: string; record: Record<string, unknown> }
+export type BranchMessage = { rkey: string; record: MessageRecord }
 
 const replyAttempt = (rkey: string) => Number(rkey.match(/\.r(\d+)$/)?.[1] ?? -1)
 
@@ -8,10 +9,7 @@ const replyAttempt = (rkey: string) => Number(rkey.match(/\.r(\d+)$/)?.[1] ?? -1
 function compare(a: BranchMessage, b: BranchMessage): number {
   const attempts = replyAttempt(a.rkey) - replyAttempt(b.rkey)
   if (attempts !== 0 && replyAttempt(a.rkey) >= 0 && replyAttempt(b.rkey) >= 0) return attempts
-  return (
-    (a.record.createdAt as string).localeCompare(b.record.createdAt as string) ||
-    a.rkey.localeCompare(b.rkey)
-  )
+  return a.record.createdAt.localeCompare(b.record.createdAt) || a.rkey.localeCompare(b.rkey)
 }
 
 /** Messages grouped by parent, each group oldest first. Messages without a known parent are roots. */
@@ -19,7 +17,7 @@ export function childrenByParent(messages: BranchMessage[]): Map<string | null,
   const known = new Set(messages.map((m) => m.rkey))
   const groups = new Map<string | null, BranchMessage[]>()
   for (const message of messages) {
-    const recorded = message.record.parent as string | undefined
+    const recorded = message.record.parent
     const parent = recorded && known.has(recorded) ? recorded : null
     groups.set(parent, [...(groups.get(parent) ?? []), message])
   }
@@ -60,7 +58,7 @@ export function choicesFor(messages: BranchMessage[], rkey: string): Record<stri
   const byKey = new Map(messages.map((m) => [m.rkey, m]))
   const choices: Record<string, string> = {}
   for (let message = byKey.get(rkey); message; ) {
-    const recorded = message.record.parent as string | undefined
+    const recorded = message.record.parent
     const parent = recorded ? byKey.get(recorded) : undefined
     choices[parent ? parent.rkey : ''] = message.rkey
     message = parent
@@ -76,7 +74,7 @@ export function inheritedModel(
   for (let i = branch.findIndex((step) => step.message.rkey === parent); i >= 0; i--) {
     const { record } = (branch[i] as { message: BranchMessage }).message
     if (record.role === 'assistant' && record.status === 'complete' && record.model)
-      return record.model as ModelRef
+      return record.model
   }
   return null
 }
diff --git a/apps/web/src/features/conversation/reply-follower.ts b/apps/web/src/features/conversation/reply-follower.ts
index b28a1e2..de80b10 100644
--- a/apps/web/src/features/conversation/reply-follower.ts
+++ b/apps/web/src/features/conversation/reply-follower.ts
@@ -6,6 +6,7 @@ import {
   useQuery,
 } from '@tanstack/react-query'
 import { useState } from 'react'
+import { isFinished, isPending } from '../../shared/message.ts'
 import { refreshConversation, useRefreshConversation } from '../../store/react.tsx'
 import type { BranchMessage } from './lib/branch.ts'
 import { addEvents, noParts, type ReplyParts, replyEvents } from './lib/reply-stream.ts'
@@ -17,9 +18,6 @@ import { addEvents, noParts, type ReplyParts, replyEvents } from './lib/reply-st
  * stream themselves, so each delta rerenders only the views that show it.
  */
 
-/** Statuses after which the reply's record is final. Others mean another server runs the reply. */
-const FINISHED = new Set(['complete', 'error', 'cancelled'])
-
 const POLL_START_MS = 2_000
 const POLL_MAX_MS = 30_000
 
@@ -32,7 +30,7 @@ const streamQuery = (skey: string, rkey: string) =>
         const url = `/api/conversations/${skey}/messages/${rkey}/stream`
         for await (const events of replyEvents(url, signal)) {
           yield events
-          if (events.some((event) => event.type === 'status' && FINISHED.has(event.status)))
+          if (events.some((event) => event.type === 'status' && isFinished(event.status)))
             void refreshConversation(client, skey)
         }
       },
@@ -56,7 +54,7 @@ const endedStreams = (results: UseQueryResult[]) =>
  */
 export function useReplyFollower(skey: string, messages: BranchMessage[]) {
   const refresh = useRefreshConversation()
-  const pending = messages.filter((m) => m.record.status === 'pending').map((m) => m.rkey)
+  const pending = messages.filter((m) => isPending(m.record)).map((m) => m.rkey)
   const [followed, setFollowed] = useState<string[]>([])
   const follow = (rkey: string) =>
     setFollowed((current) => (current.includes(rkey) ? current : [...current, rkey]))
@@ -107,7 +105,8 @@ export interface FollowedReply {
 /** A followed reply as it streams, rerendering with each delta. */
 export function useFollowedReply(skey: string, rkey: string): FollowedReply {
   const { data, isError } = useQuery({ ...streamQuery(skey, rkey), enabled: false })
-  const elsewhere = Boolean(data?.status && !FINISHED.has(data.status))
+  // A status that isn't final means another server runs the reply.
+  const elsewhere = Boolean(data?.status && !isFinished(data.status))
   return {
     streamed: data ?? null,
     notLive: isError ? 'dropped' : elsewhere ? 'elsewhere' : null,
diff --git a/apps/web/src/features/sharing/pages/SharedPage.tsx b/apps/web/src/features/sharing/pages/SharedPage.tsx
index d2a0fcc..80e6166 100644
--- a/apps/web/src/features/sharing/pages/SharedPage.tsx
+++ b/apps/web/src/features/sharing/pages/SharedPage.tsx
@@ -1,5 +1,6 @@
 import { useSuspenseQuery } from '@tanstack/react-query'
 import { useLocation } from '@tanstack/react-router'
+import type { MessageRecord } from '../../../shared/message.ts'
 import { button } from '../../../shared/ui/Button.tsx'
 import { useDocumentTitle } from '../../../shared/useDocumentTitle.ts'
 import { BranchView } from '../../conversation/components/BranchView.tsx'
@@ -46,7 +47,7 @@ function SharedChat(props: ChatProps) {
   const { data: shared } = useSuspenseQuery(sharedQuery(props.ownerDid, props.skey))
   const messages = shared.messages.map((m) => ({
     rkey: m.rkey,
-    record: m.value as Record<string, unknown>,
+    record: m.value as MessageRecord,
   }))
   const { branch, pick } = useBranch(messages)
   // An untitled chat keeps the route's title, Shared chat.
diff --git a/apps/web/src/parts/WorkSteps.tsx b/apps/web/src/parts/WorkSteps.tsx
index a571b60..bc2ab9a 100644
--- a/apps/web/src/parts/WorkSteps.tsx
+++ b/apps/web/src/parts/WorkSteps.tsx
@@ -1,6 +1,7 @@
 import { memo, type ReactNode, type SyntheticEvent, useState } from 'react'
 import { cn } from '../shared/cn.ts'
 import { ChevronDownIcon, ChevronRightIcon } from '../shared/icons.tsx'
+import type { MessageRecord } from '../shared/message.ts'
 import { action } from '../shared/ui/actions.ts'
 import { Badge } from '../shared/ui/Badge.tsx'
 import { Markdown } from './markdown.tsx'
@@ -20,7 +21,7 @@ import type { BlobUrl } from './types.ts'
 interface Props {
   steps: Step[]
   /** The message the steps belong to, whose status tells a tool still running from one cut off. */
-  record: Record<string, unknown>
+  record: MessageRecord
   /** Whether the model is still working in this block, so its last step is the current one. */
   live: boolean
   blobUrl: BlobUrl
@@ -33,7 +34,7 @@ const clockId = (scope: string | undefined, step: Step) =>
   scope ? `${scope}:${step.key}` : undefined
 
 /** What the model is doing right now, from the last step it took. */
-function activity(step: Step | undefined, record: Record<string, unknown>): string {
+function activity(step: Step | undefined, record: MessageRecord): string {
   if (step?.kind === 'reasoning') return 'Thinking…'
   if (step?.kind === 'tool' && toolStatus(step.result, record) === 'running')
     return `${toolEntry(step.call.tool as string).activity}…`
@@ -41,7 +42,7 @@ function activity(step: Step | undefined, record: Record<string, unknown>): stri
 }
 
 /** Whether a step is still going: reasoning still streaming, or a tool waiting for its result. */
-const isRunning = (step: Step, current: boolean, record: Record<string, unknown>) =>
+const isRunning = (step: Step, current: boolean, record: MessageRecord) =>
   step.kind === 'reasoning' ? current : toolStatus(step.result, record) === 'running'
 
 const breathe = 'animate-breathe motion-reduce:animate-none'
@@ -83,7 +84,7 @@ function Elapsed(props: ElapsedProps) {
 
 interface ActivityProps {
   step: Step | undefined
-  record: Record<string, unknown>
+  record: MessageRecord
   scope?: string
 }
 
@@ -204,7 +205,7 @@ export function WorkButton(props: WorkButtonProps) {
 interface WorkListProps {
   id: string
   steps: Step[]
-  record: Record<string, unknown>
+  record: MessageRecord
   blobUrl: BlobUrl
   scope?: string
 }
@@ -223,7 +224,7 @@ const railRow = cn(
 
 interface RailDotProps {
   step: Step
-  record: Record<string, unknown>
+  record: MessageRecord
 }
 
 /**
@@ -276,7 +277,7 @@ export function WorkList(props: WorkListProps) {
 interface StepViewProps {
   step: Step
   current: boolean
-  record: Record<string, unknown>
+  record: MessageRecord
   blobUrl: BlobUrl
   /** The step's clock id, when its reply is known. */
   clock?: string
@@ -397,7 +398,7 @@ function ReasoningLabel(props: ReasoningLabelProps) {
 interface ToolStepProps {
   step: Extract<Step, { kind: 'tool' }>
   status: ToolStatus
-  record: Record<string, unknown>
+  record: MessageRecord
   blobUrl: BlobUrl
   /** Seconds the tool has been running, while it runs. */
   elapsed?: number
diff --git a/apps/web/src/parts/tool-status.ts b/apps/web/src/parts/tool-status.ts
index 5d55b1f..a3e4d9a 100644
--- a/apps/web/src/parts/tool-status.ts
+++ b/apps/web/src/parts/tool-status.ts
@@ -1,3 +1,4 @@
+import { isPending, type MessageRecord } from '../shared/message.ts'
 import type { Part } from './types.ts'
 
 /** Where one tool call stands, which its row, badge, timer, and the live line all read. */
@@ -8,7 +9,7 @@ export type ToolStatus = 'running' | 'done' | 'error' | 'incomplete'
  * while its message is still being written, and incomplete once the message stopped, failed, or
  * finished without one.
  */
-export function toolStatus(result: Part | undefined, record: Record<string, unknown>): ToolStatus {
+export function toolStatus(result: Part | undefined, record: MessageRecord): ToolStatus {
   if (result) return result.isError ? 'error' : 'done'
-  return record.status === 'pending' ? 'running' : 'incomplete'
+  return isPending(record) ? 'running' : 'incomplete'
 }
diff --git a/apps/web/src/parts/types.ts b/apps/web/src/parts/types.ts
index a1b790d..402dfb3 100644
--- a/apps/web/src/parts/types.ts
+++ b/apps/web/src/parts/types.ts
@@ -1,4 +1,5 @@
 import type { ComponentType } from 'react'
+import type { MessageRecord } from '../shared/message.ts'
 import type { ToolStatus } from './tool-status.ts'
 
 /** A message part as stored, in its lexicon's JSON form. */
@@ -20,7 +21,7 @@ export type BlobUrl = (cid: string, mimeType?: string) => string
 export interface PartViewProps {
   part: Part
   /** The message record the part belongs to. */
-  record: Record<string, unknown>
+  record: MessageRecord
   blobUrl: BlobUrl
   /** Whether the part is still being written, as the newest part of a reply that streams. */
   live?: boolean
@@ -37,7 +38,7 @@ export interface ToolViewProps {
   result: Part | undefined
   status: ToolStatus
   /** The message record the call belongs to. */
-  record: Record<string, unknown>
+  record: MessageRecord
   blobUrl: BlobUrl
 }
 
diff --git a/apps/web/src/shared/message.ts b/apps/web/src/shared/message.ts
new file mode 100644
index 0000000..65b9105
--- /dev/null
+++ b/apps/web/src/shared/message.ts
@@ -0,0 +1,30 @@
+import type { MessageRecord } from '@scn-chat/lexicons'
+import { nsid } from '@scn-chat/lexicons/nsid'
+import type { Part } from '../parts/types.ts'
+
+export type { MessageRecord }
+
+/**
+ * The statuses after which a reply's record changes no more. Another client may write a status
+ * this app doesn't know, which is neither pending nor finished.
+ */
+const FINISHED = new Set<string>(['complete', 'error', 'cancelled'])
+
+/** Whether a reply is still being written. */
+export const isPending = (record: MessageRecord) => record.status === 'pending'
+
+/** Whether a reply's status, from its record or its stream, is final. */
+export const isFinished = (status: string | null | undefined) =>
+  status !== null && status !== undefined && FINISHED.has(status)
+
+/** Whether the message's content is encrypted, so the app can't show it. */
+export const isEncrypted = (record: MessageRecord) =>
+  record.content.$type === `${nsid.defs}#encryptedContent`
+
+/** A message's parts. Encrypted content, and content of a kind this app doesn't know, have none. */
+export const partsOf = (record: MessageRecord): Part[] =>
+  (record.content as { parts?: Part[] }).parts ?? []
+
+/** Who wrote a message: the user, or the model that wrote the reply. */
+export const authorOf = (record: MessageRecord): string =>
+  record.role === 'user' ? 'You' : (record.model?.id ?? 'Assistant')
diff --git a/apps/web/src/store/core.ts b/apps/web/src/store/core.ts
index 68477e1..876d100 100644
--- a/apps/web/src/store/core.ts
+++ b/apps/web/src/store/core.ts
@@ -1,3 +1,4 @@
+import type { InfoRecord, MessageRecord } from '@scn-chat/lexicons'
 import { nsid } from '@scn-chat/lexicons/nsid'
 import { type SearchResult, search } from './search.ts'
 import type { SqlDb } from './sql.ts'
@@ -26,8 +27,9 @@ export type ChatPage = { chats: ChatListItem[]; next: ChatCursor | null }
 export type TagCount = { tag: string; count: number }
 /** How current the local copy is: when the chat index last synced, and chats left to download. */
 export type SyncStatus = { syncedAt: string | null; remaining: number }
-export type StoredMessage = { rkey: string; author: string; record: Json; cid: string }
-export type Conversation = { skey: string; info: Json | null; messages: StoredMessage[] }
+// The server sends only records valid against the lexicons, so the local copy holds them typed.
+export type StoredMessage = { rkey: string; author: string; record: MessageRecord; cid: string }
+export type Conversation = { skey: string; info: InfoRecord | null; messages: StoredMessage[] }
 
 export type IndexChanges = {
   conversations: (ConversationSummary & { cid: string })[]
@@ -196,10 +198,10 @@ export class StoreCore {
       .map((row) => ({
         rkey: row.rkey,
         author: row.author_did,
-        record: JSON.parse(row.record_json) as Json,
+        record: JSON.parse(row.record_json) as MessageRecord,
         cid: row.cid,
       }))
-    return { skey, info: info ? (JSON.parse(info.record_json) as Json) : null, messages }
+    return { skey, info: info ? (JSON.parse(info.record_json) as InfoRecord) : null, messages }
   }
 
   /** Fetch the chat index, or only its changes since the stored revision. */
diff --git a/apps/web/tests/features/conversation/chat.test.tsx b/apps/web/tests/features/conversation/chat.test.tsx
index fa8e326..6e209e9 100644
--- a/apps/web/tests/features/conversation/chat.test.tsx
+++ b/apps/web/tests/features/conversation/chat.test.tsx
@@ -6,6 +6,7 @@ import type { BranchMessage } from '../../../src/features/conversation/lib/branc
 import { StoreProvider } from '../../../src/store/react.tsx'
 import { FakeEventSource, stubEventSource } from '../../helpers/event-source.ts'
 import { stubFetch, writes } from '../../helpers/fetch.ts'
+import { messageRecord } from '../../helpers/records.ts'
 import { renderAt } from '../../helpers/router.tsx'
 import { testStore } from '../../helpers/store.ts'
 
@@ -15,11 +16,15 @@ const text = (value: string) => ({
 })
 const user = (rkey: string, parent?: string): BranchMessage => ({
   rkey,
-  record: { role: 'user', content: { parts: [text('q')] }, ...(parent ? { parent } : {}) },
+  record: messageRecord({
+    role: 'user',
+    content: { parts: [text('q')] },
+    ...(parent ? { parent } : {}),
+  }),
 })
 const reply = (rkey: string, parent: string, status = 'complete'): BranchMessage => ({
   rkey,
-  record: { role: 'assistant', parent, status, content: { parts: [] } },
+  record: messageRecord({ parent, status }),
 })
 
 let chat: ReturnType<typeof useChat>
diff --git a/apps/web/tests/features/conversation/components/MessageView.test.tsx b/apps/web/tests/features/conversation/components/MessageView.test.tsx
index 81e6036..b220195 100644
--- a/apps/web/tests/features/conversation/components/MessageView.test.tsx
+++ b/apps/web/tests/features/conversation/components/MessageView.test.tsx
@@ -4,17 +4,19 @@ import { describe, expect, it, vi } from 'vitest'
 import { MessageView } from '../../../../src/features/conversation/components/MessageView.tsx'
 import { StreamingReply } from '../../../../src/features/conversation/components/PendingReply.tsx'
 import { noParts } from '../../../../src/features/conversation/lib/reply-stream.ts'
+import { partsOf } from '../../../../src/shared/message.ts'
+import { messageRecord } from '../../../helpers/records.ts'
 
 const d = (name: string) => `network.sharedcomputer.chat.defs#${name}`
 const blobUrl = (cid: string) => `/blob/${cid}`
 /** A reply's record while it streams. */
-const streaming = {
+const streaming = messageRecord({
   role: 'assistant',
   status: 'pending',
   content: { $type: d('plainContent'), parts: [] },
-}
+})
 
-const working = {
+const working = messageRecord({
   role: 'assistant',
   status: 'complete',
   content: {
@@ -26,7 +28,7 @@ const working = {
       { $type: d('textPart'), text: 'Found it' },
     ],
   },
-}
+})
 
 describe('MessageView', () => {
   it('keeps the steps of a finished reply behind a footer button that opens them under it', async () => {
@@ -48,16 +50,16 @@ describe('MessageView', () => {
   })
 
   it('shows a thought as a row with a glimpse of its first line, which opens onto all of it', async () => {
-    const record = {
+    const record = messageRecord({
       ...working,
       content: {
         $type: d('plainContent'),
         parts: [
           { $type: d('reasoningPart'), text: '\n## **Planning** the `search`\n\nThen look closer' },
-          ...working.content.parts.slice(1),
+          ...partsOf(working).slice(1),
         ],
       },
-    }
+    })
     const { container } = render(<MessageView blobUrl={blobUrl} record={record} />)
     await userEvent.click(screen.getByRole('button', { name: 'Thought · lookup' }))
     const thought = container.querySelector('[data-step=reasoning]') as HTMLDetailsElement
@@ -102,7 +104,10 @@ describe('MessageView', () => {
     render(
       <MessageView
         blobUrl={blobUrl}
-        record={{ ...working, model: { provider: 'anthropic', id: 'claude-sonnet-5-5' } }}
+        record={messageRecord({
+          ...working,
+          model: { provider: 'anthropic', id: 'claude-sonnet-5-5' },
+        })}
       />,
     )
     expect(screen.getByText('claude-sonnet-5-5')).toBeInTheDocument()
@@ -128,7 +133,7 @@ describe('MessageView', () => {
     const { container } = render(
       <MessageView
         blobUrl={blobUrl}
-        record={{
+        record={messageRecord({
           role: 'assistant',
           status: 'complete',
           content: {
@@ -138,7 +143,7 @@ describe('MessageView', () => {
               { $type: d('sourcePart'), url: 'https://example.com', title: 'Example' },
             ],
           },
-        }}
+        })}
       />,
     )
     expect(container.querySelector('details:not([data-sources])')).toBeNull()
@@ -153,14 +158,14 @@ describe('MessageView', () => {
     render(
       <MessageView
         blobUrl={blobUrl}
-        record={{
+        record={messageRecord({
           role: 'assistant',
           status: 'complete',
           content: {
             $type: d('plainContent'),
             parts: [{ $type: d('sourcePart'), url: 'https://www.example.com/a/long/path?q=1' }],
           },
-        }}
+        })}
       />,
     )
     const link = screen.getByRole('link', { name: 'example.com' })
@@ -171,7 +176,7 @@ describe('MessageView', () => {
     render(
       <MessageView
         blobUrl={blobUrl}
-        record={{
+        record={messageRecord({
           role: 'assistant',
           status: 'complete',
           content: {
@@ -181,7 +186,7 @@ describe('MessageView', () => {
               { $type: d('sourcePart'), url: 'https://other.org/b' },
             ],
           },
-        }}
+        })}
       />,
     )
     const sources = screen.getByRole('region', { name: 'Sources' })
@@ -197,7 +202,7 @@ describe('MessageView', () => {
     render(
       <MessageView
         blobUrl={blobUrl}
-        record={{
+        record={messageRecord({
           role: 'assistant',
           status: 'complete',
           content: {
@@ -208,7 +213,7 @@ describe('MessageView', () => {
               title: `Source ${i + 1}`,
             })),
           },
-        }}
+        })}
       />,
     )
     const sources = screen.getByRole('region', { name: 'Sources' })
@@ -225,14 +230,14 @@ describe('MessageView', () => {
     render(
       <MessageView
         blobUrl={blobUrl}
-        record={{
+        record={messageRecord({
           role: 'assistant',
           status: 'complete',
           content: {
             $type: d('plainContent'),
             parts: [{ $type: d('textPart'), text: 'Run:\n\n```sh\npnpm dev\npnpm check\n```' }],
           },
-        }}
+        })}
       />,
     )
     await user.click(screen.getByRole('button', { name: 'Copy' }))
@@ -244,7 +249,7 @@ describe('MessageView', () => {
     const { container } = render(
       <MessageView
         blobUrl={blobUrl}
-        record={{
+        record={messageRecord({
           role: 'assistant',
           status: 'complete',
           content: {
@@ -256,7 +261,7 @@ describe('MessageView', () => {
               },
             ],
           },
-        }}
+        })}
       />,
     )
     expect(container.querySelector('.markdown strong')).toHaveTextContent('bold')
@@ -268,7 +273,7 @@ describe('MessageView', () => {
     const { container } = render(
       <MessageView
         blobUrl={blobUrl}
-        record={{
+        record={messageRecord({
           role: 'assistant',
           status: 'complete',
           content: {
@@ -280,7 +285,7 @@ describe('MessageView', () => {
               },
             ],
           },
-        }}
+        })}
       />,
     )
     expect(container.querySelector('img')).toBeNull()
@@ -291,14 +296,14 @@ describe('MessageView', () => {
     const { container } = render(
       <MessageView
         blobUrl={blobUrl}
-        record={{
+        record={messageRecord({
           role: 'assistant',
           status: 'complete',
           content: {
             $type: d('plainContent'),
             parts: [{ $type: d('textPart'), text: '![chart](https://example.com/c.png?q=secret)' }],
           },
-        }}
+        })}
       />,
     )
     expect(container.querySelector('img')).toBeNull()
@@ -314,10 +319,10 @@ describe('MessageView', () => {
     render(
       <MessageView
         blobUrl={blobUrl}
-        record={{
+        record={messageRecord({
           role: 'user',
           content: { $type: d('plainContent'), parts: [{ $type: d('textPart'), text: '**raw**' }] },
-        }}
+        })}
       />,
     )
     expect(screen.getByText('**raw**')).toBeInTheDocument()
@@ -327,13 +332,13 @@ describe('MessageView', () => {
     const { container } = render(
       <MessageView
         blobUrl={blobUrl}
-        record={{
+        record={messageRecord({
           role: 'user',
           content: {
             $type: d('plainContent'),
             parts: [{ $type: d('textPart'), text: '> quoted **bit**\n\nAbout this:' }],
           },
-        }}
+        })}
       />,
     )
     const quote = container.querySelector('article blockquote')
@@ -396,12 +401,14 @@ describe('MessageView', () => {
     const { container } = render(
       <MessageView
         blobUrl={blobUrl}
-        record={{
+        record={messageRecord({
           role: 'assistant',
           status: 'pending',
           model: { provider: 'anthropic', id: 'claude-sonnet-5-5' },
           content: { $type: d('plainContent'), parts: [] },
-        }}
+          // Just asked for, so it has waited no whole second yet.
+          createdAt: new Date().toISOString(),
+        })}
       />,
     )
     const header = container.querySelector('header') as HTMLElement
@@ -413,23 +420,23 @@ describe('MessageView', () => {
     const { rerender } = render(
       <MessageView
         blobUrl={blobUrl}
-        record={{
+        record={messageRecord({
           role: 'assistant',
           status: 'error',
           error: 'rate limited',
           content: { $type: d('plainContent'), parts: [] },
-        }}
+        })}
       />,
     )
     expect(screen.getByRole('alert')).toHaveTextContent('rate limited')
     rerender(
       <MessageView
         blobUrl={blobUrl}
-        record={{
+        record={messageRecord({
           role: 'assistant',
           status: 'cancelled',
           content: { $type: d('plainContent'), parts: [] },
-        }}
+        })}
       />,
     )
     expect(screen.getByText('Stopped')).toBeInTheDocument()
@@ -439,7 +446,7 @@ describe('MessageView', () => {
     render(
       <MessageView
         blobUrl={blobUrl}
-        record={{
+        record={messageRecord({
           role: 'user',
           content: {
             $type: d('plainContent'),
@@ -451,7 +458,7 @@ describe('MessageView', () => {
               },
             ],
           },
-        }}
+        })}
       />,
     )
     expect(screen.getByAltText('a cat')).toHaveAttribute('src', '/blob/img1')
@@ -461,7 +468,7 @@ describe('MessageView', () => {
     render(
       <MessageView
         blobUrl={(cid, type) => `/blob/${cid}${type ? `?type=${type}` : ''}`}
-        record={{
+        record={messageRecord({
           role: 'user',
           content: {
             $type: d('plainContent'),
@@ -482,7 +489,7 @@ describe('MessageView', () => {
               },
             ],
           },
-        }}
+        })}
       />,
     )
     const pdf = screen.getByRole('link', { name: /report\.pdf/ })
@@ -506,7 +513,7 @@ describe('MessageView', () => {
     render(
       <MessageView
         blobUrl={blobUrl}
-        record={{
+        record={messageRecord({
           role: 'user',
           content: {
             $type: d('plainContent'),
@@ -521,7 +528,7 @@ describe('MessageView', () => {
               file('c', 'c.pdf'),
             ],
           },
-        }}
+        })}
       />,
     )
     const rows = screen.getAllByRole('list', { name: 'Files' })
@@ -542,7 +549,10 @@ describe('MessageView', () => {
     render(
       <MessageView
         blobUrl={blobUrl}
-        record={{ role: 'assistant', content: { $type: d('plainContent'), parts: [] } }}
+        record={messageRecord({
+          role: 'assistant',
+          content: { $type: d('plainContent'), parts: [] },
+        })}
         siblings={{ index: 1, count: 3, previous: 'a', next: 'c', onPick }}
       />,
     )
@@ -555,7 +565,7 @@ describe('MessageView', () => {
     render(
       <MessageView
         blobUrl={blobUrl}
-        record={{ role: 'user', content: { $type: d('encryptedContent') } }}
+        record={messageRecord({ role: 'user', content: { $type: d('encryptedContent') } })}
       />,
     )
     expect(screen.getByText('This message is encrypted.')).toBeInTheDocument()
@@ -576,14 +586,14 @@ const result = (callId: string, output: unknown, more: Record<string, unknown> =
 })
 /** A finished reply that made these tool parts, with its steps opened from the footer. */
 async function openSteps(parts: object[], status = 'complete') {
-  const record = {
+  const record = messageRecord({
     role: 'assistant',
     status,
     content: {
       $type: d('plainContent'),
       parts: [...parts, { $type: d('textPart'), text: 'Done' }],
     },
-  }
+  })
   const view = render(<MessageView blobUrl={blobUrl} record={record} />)
   const footer = view.container.querySelector('footer') as HTMLElement
   await userEvent.click(within(footer).getByRole('button'))
diff --git a/apps/web/tests/features/conversation/components/RecordDetails.test.tsx b/apps/web/tests/features/conversation/components/RecordDetails.test.tsx
index 26c1b32..d07d73a 100644
--- a/apps/web/tests/features/conversation/components/RecordDetails.test.tsx
+++ b/apps/web/tests/features/conversation/components/RecordDetails.test.tsx
@@ -5,6 +5,7 @@ import {
   DetailsButton,
   recordRows,
 } from '../../../../src/features/conversation/components/RecordDetails.tsx'
+import { messageRecord } from '../../../helpers/records.ts'
 
 describe('RecordDetails', () => {
   it('shows what the record says about a reply, when it was written, and where it lives', async () => {
@@ -12,13 +13,12 @@ describe('RecordDetails', () => {
     const rows = recordRows({
       rkey: 'u.r0',
       storedIn: 'Your PDS',
-      record: {
-        role: 'assistant',
+      record: messageRecord({
         status: 'complete',
         model: { provider: 'anthropic', id: 'claude-sonnet-5-5' },
         usage: { inputTokens: 1200, outputTokens: 80 },
         createdAt,
-      },
+      }),
     })
     render(<DetailsButton rows={rows} />)
     await userEvent.click(screen.getByRole('button', { name: 'Details' }))
diff --git a/apps/web/tests/features/conversation/lib/branch.test.ts b/apps/web/tests/features/conversation/lib/branch.test.ts
index cc2d848..5b3d929 100644
--- a/apps/web/tests/features/conversation/lib/branch.test.ts
+++ b/apps/web/tests/features/conversation/lib/branch.test.ts
@@ -5,10 +5,11 @@ import {
   currentBranch,
   inheritedModel,
 } from '../../../../src/features/conversation/lib/branch.ts'
+import { messageRecord } from '../../../helpers/records.ts'
 
 const m = (rkey: string, parent?: string, createdAt = '2026-09-26T00:00:00Z') => ({
   rkey,
-  record: { parent, createdAt },
+  record: messageRecord({ parent, createdAt }),
 })
 
 describe('currentBranch', () => {
@@ -85,7 +86,9 @@ describe('choicesFor', () => {
 const smart = { provider: 'p', id: 'smart' }
 const fast = { provider: 'p', id: 'fast' }
 
-const step = (rkey: string, record: Record<string, unknown>) => ({ message: { rkey, record } })
+const step = (rkey: string, fields: Record<string, unknown>) => ({
+  message: { rkey, record: messageRecord(fields) },
+})
 const user = (rkey: string) => step(rkey, { role: 'user' })
 const reply = (rkey: string, model: object, status = 'complete') =>
   step(rkey, { role: 'assistant', status, model })
diff --git a/apps/web/tests/features/conversation/lib/outline.test.ts b/apps/web/tests/features/conversation/lib/outline.test.ts
index 8870333..89a67b9 100644
--- a/apps/web/tests/features/conversation/lib/outline.test.ts
+++ b/apps/web/tests/features/conversation/lib/outline.test.ts
@@ -1,6 +1,7 @@
 import { describe, expect, it } from 'vitest'
 import { currentBranch } from '../../../../src/features/conversation/lib/branch.ts'
 import { outlineOf } from '../../../../src/features/conversation/lib/outline.ts'
+import { messageRecord } from '../../../helpers/records.ts'
 
 const d = (name: string) => `network.sharedcomputer.chat.defs#${name}`
 const message = (
@@ -10,12 +11,12 @@ const message = (
   extra: Record<string, unknown> = {},
 ) => ({
   rkey,
-  record: {
+  record: messageRecord({
     role,
     content: { $type: d('plainContent'), parts },
     createdAt: '2026-10-07T09:00:00Z',
     ...extra,
-  },
+  }),
 })
 const text = (value: string) => ({ $type: d('textPart'), text: value })
 
diff --git a/apps/web/tests/features/conversation/reply-follower.test.tsx b/apps/web/tests/features/conversation/reply-follower.test.tsx
index 2a7a26c..8b90602 100644
--- a/apps/web/tests/features/conversation/reply-follower.test.tsx
+++ b/apps/web/tests/features/conversation/reply-follower.test.tsx
@@ -9,13 +9,14 @@ import {
 } from '../../../src/features/conversation/reply-follower.ts'
 import { StoreProvider, useConversation } from '../../../src/store/react.tsx'
 import { FakeEventSource, lastSource, stubEventSource } from '../../helpers/event-source.ts'
+import { messageRecord } from '../../helpers/records.ts'
 import { renderAt } from '../../helpers/router.tsx'
 import { testStore } from '../../helpers/store.ts'
 
-const user: BranchMessage = { rkey: 'u', record: { role: 'user' } }
+const user: BranchMessage = { rkey: 'u', record: messageRecord({ role: 'user' }) }
 const reply = (status: string): BranchMessage => ({
   rkey: 'u.r0',
-  record: { role: 'assistant', parent: 'u', status },
+  record: messageRecord({ parent: 'u', status }),
 })
 
 let follow: (rkey: string) => void
diff --git a/apps/web/tests/helpers/records.ts b/apps/web/tests/helpers/records.ts
new file mode 100644
index 0000000..da1b9b1
--- /dev/null
+++ b/apps/web/tests/helpers/records.ts
@@ -0,0 +1,16 @@
+import { nsid } from '@scn-chat/lexicons/nsid'
+import type { MessageRecord } from '../../src/shared/message.ts'
+
+/**
+ * A message record for a test: a reply with no parts unless `fields` says otherwise, with the
+ * fields every record has filled in. Its parts can be written as loosely as the part views read
+ * them.
+ */
+export const messageRecord = (fields: Record<string, unknown> = {}): MessageRecord =>
+  ({
+    $type: nsid.message,
+    role: 'assistant',
+    content: { $type: `${nsid.defs}#plainContent`, parts: [] },
+    createdAt: '2026-09-26T00:00:00Z',
+    ...fields,
+  }) as MessageRecord
diff --git a/apps/web/tests/shared/message.test.ts b/apps/web/tests/shared/message.test.ts
new file mode 100644
index 0000000..e945b36
--- /dev/null
+++ b/apps/web/tests/shared/message.test.ts
@@ -0,0 +1,35 @@
+import { describe, expect, it } from 'vitest'
+import { authorOf, isEncrypted, isFinished, isPending, partsOf } from '../../src/shared/message.ts'
+import { messageRecord } from '../helpers/records.ts'
+
+const d = (name: string) => `network.sharedcomputer.chat.defs#${name}`
+
+describe('message records', () => {
+  it('tells a reply still being written from a finished one', () => {
+    expect(isPending(messageRecord({ status: 'pending' }))).toBe(true)
+    expect(isPending(messageRecord({ status: 'complete' }))).toBe(false)
+    for (const status of ['complete', 'error', 'cancelled']) expect(isFinished(status)).toBe(true)
+  })
+
+  it("takes a status it doesn't know, from another client, as neither pending nor finished", () => {
+    expect(isPending(messageRecord({ status: 'paused' }))).toBe(false)
+    expect(isFinished('paused')).toBe(false)
+    expect(isFinished(null)).toBe(false)
+  })
+
+  it('gives the parts of plain content, and none of encrypted content', () => {
+    const text = { $type: d('textPart'), text: 'hi' }
+    const plain = messageRecord({ content: { $type: d('plainContent'), parts: [text] } })
+    const sealed = messageRecord({ content: { $type: d('encryptedContent'), ciphertext: 'x' } })
+    expect(partsOf(plain)).toEqual([text])
+    expect(isEncrypted(plain)).toBe(false)
+    expect(partsOf(sealed)).toEqual([])
+    expect(isEncrypted(sealed)).toBe(true)
+  })
+
+  it("names the user, or the reply's model, or the assistant when no model is known", () => {
+    expect(authorOf(messageRecord({ role: 'user' }))).toBe('You')
+    expect(authorOf(messageRecord({ model: { provider: 'p', id: 'claude' } }))).toBe('claude')
+    expect(authorOf(messageRecord())).toBe('Assistant')
+  })
+})
diff --git a/specs/extending.md b/specs/extending.md
index 27d51c0..b469dd2 100644
--- a/specs/extending.md
+++ b/specs/extending.md
@@ -60,7 +60,7 @@ export const toolViews: Record<string, ToolEntry> = {
 export const StepsView: StepsView = Steps
 ```
 
-- **Part views** get `{ part, record, blobUrl }`: the part as stored, the message record it belongs to, and the function that builds a blob's URL. A part's type comes from its lexicon, in its JSON form.
+- **Part views** get `{ part, record, blobUrl }`: the part as stored, the message record it belongs to, typed as the lexicon's `MessageRecord`, and the function that builds a blob's URL. What a record's status means, its parts, and who wrote it come from `src/shared/message.ts`. A part's type comes from its lexicon, in its JSON form.
 - **Tool views**, their entries, the default view, and the tool status are [[tool-views]].
 - **Unknown kinds.** A part kind with no view is skipped, as now, so records written by newer clients still show what this one understands.
 - **What stays in `MessageView`.** It keeps the message's layout: the header and sibling controls, the `pending` slot for a pending reply's stream, the list of source links at the end, the status lines, and the actions. Only drawing parts moves into the tables.
-- 
knotmirror 0.0.1