fix(chat): keep a long turn's Edited N files card whole across the page cut (#86)

The reported turn (/vp-auto, ~120 messages) showed "Edited 1 file": the
chat loads the newest 50 messages, and the turn's other Write
(rbac_routes_test.go, +176) was in the part before the page.

- turnCarry (agent-edits.js): every message the route's sliding window
  drops goes through it; it keeps the file changes since the last prompt it
  dropped (a dropped call whose result is on the page, and dropped
  subagents, included).
- A Claude page that starts mid-turn answers them as `turn_edits`; the
  chat keeps the one from the page that holds its oldest message and adds
  it to that turn's card.

Files a turn changed through Bash (python/sed writing a file) are still not
listed: nothing in the transcript says which files a command wrote.

client/src/components/conversation/MessageList.tsx

@@ -172,6 +172,9 @@ interface MessageListProps {
   /** A subagent's conversation inside its step: tight spacing, and the task
    *  the orchestrator gave it reads as the prompt it is. */
   compact?: boolean;
+  /** The files the first, cut-off turn changed before `messages` begins (the
+   *  transcript page's `turn_edits`): counted in that turn's card. */
+  leadEdits?: TranscriptContent["edits"];
 }
 
 /** Build a map from tool_use id → tool_result for matching */
@@ -493,6 +496,8 @@ type Item =
 const EDIT_TOOLS = new Set(["Write", "Edit", "MultiEdit", "NotebookEdit"]);
 // A subagent's result carries the files IT changed (`edits`): they count too.
 const AGENT_TOOLS = new Set(["Agent", "Task"]);
+// The stand-in for the part of a turn the page cut off: its `edits` count.
+const LEAD = "__lead_edits";
 
 /** A line that is only Claude Code's local-command plumbing — the caveat it
  *  writes first, the command, what the command printed — or null for
@@ -517,11 +522,18 @@ export function localCommand(
   return { name, output, error };
 }
 
-export function chatItems(messages: TranscriptMessage[], keys: string[]): Item[] {
+export function chatItems(
+  messages: TranscriptMessage[],
+  keys: string[],
+  leadEdits?: TranscriptContent["edits"]
+): Item[] {
   const items: Item[] = [];
   // The file-changing calls of the turn so far, closed into one card when the
-  // human speaks again (or the list ends).
-  let edits: TranscriptContent[] = [];
+  // human speaks again (or the list ends) — starting with what the page's
+  // cut-off first turn changed before it.
+  let edits: TranscriptContent[] = leadEdits?.length
+    ? [{ type: "tool_use", name: LEAD, edits: leadEdits }]
+    : [];
   // The turn's prompt time, its newest assistant line and its output so far,
   // for the "Done in …" line under a turn that ended.
   let start: string | null = null;
@@ -684,8 +696,8 @@ function EditedFilesCard({
   const byAgent = new Set<string>();
   for (const b of blocks) {
     const r0 = b.id ? toolResultMap.get(b.id) : undefined;
-    if (AGENT_TOOLS.has(b.name ?? "")) {
-      for (const e of r0?.edits ?? []) {
+    if (AGENT_TOOLS.has(b.name ?? "") || b.name === LEAD) {
+      for (const e of (b.name === LEAD ? b.edits : r0?.edits) ?? []) {
         if (!files.has(e.path)) byAgent.add(e.path);
         const f = files.get(e.path) ?? { added: 0, removed: 0, counted: false };
         f.added += e.added;
@@ -798,6 +810,7 @@ function MessageListView({
   sessionId,
   agentLinks,
   compact = false,
+  leadEdits,
 }: MessageListProps) {
   const { t } = useTranslation("sessions");
   const toolResultMap = useMemo(() => buildToolResultMap(messages), [messages]);
@@ -823,9 +836,10 @@ function MessageListView({
               m.sender === "orchestrator" ? { ...m, sender: "user" as const } : m
             )
           : messages,
-        keys
+        keys,
+        leadEdits
       ),
-    [messages, keys, compact]
+    [messages, keys, compact, leadEdits]
   );
   const agents = useMemo(
     () => (live ? backgroundAgents(messages, toolResultMap) : []),