fix(chat): recall the current session's prompts by default; tidy the six merged PRs

Input history (#3035) shipped with "All projects" as the default scope and
only recorded prompts sent after the upgrade, so ArrowUp showed other
sessions' prompts and, once switched to "Current session", nothing at all.
Default to the current session and merge the visible transcript's prompts
with the persisted bucket. Existing sessions recall as they did before
#3035, while new prompts keep their attachments and stay recallable after
a revert hides them from the transcript.

Cleanup across #1855, #2297, #3072, #3178, #3035 and #3135: drop the
duplicate poll guards in the file content poller, the zod schema the
VS Code package cannot depend on, a copied file-URL helper and stray
whitespace; move the Enter-to-send strings into the settings namespace;
document OPENCHAMBER_CHATS_DIR, resolve the chats root once on the server
and warm it alongside the other bootstrap calls.

packages/ui/src/components/chat/ChatInput.tsx

@@ -175,7 +175,9 @@ import {
     buildChatInputHistorySubmissions,
     buildInputHistoryNavigatorIdentity,
     mapInputHistoryEntriesToValues,
+    mergeSessionInputHistory,
 } from './inputHistory';
+import { useUserMessageHistory } from '@/sync/sync-context';
 
 // Lazy like in ChatMessage: a static import would pull the @pierre/diffs and
 // Shiki stacks into the eager startup graph for a dialog opened on demand.
@@ -198,7 +200,6 @@ const MAX_MOBILE_COMPOSER_LINES = 16;
  */
 const MOBILE_COMPOSER_BOUND_GAP_PX = 4;
 const EMPTY_QUEUE: QueuedMessage[] = [];
-const EMPTY_INPUT_HISTORY_ENTRIES = Object.freeze([] as const);
 const COMPACT_CHAT_PLACEHOLDER_MAX_WIDTH = 560;
 const renameFileForAttachmentCitation = (file: File, filename: string): File => {
     if (file.name === filename) {
@@ -908,13 +909,18 @@ const ChatInputComponent: React.FC<ChatInputProps> = ({
         ),
         [activeRuntimeKey, currentDirectory, currentSessionDirectoryForSync, currentSessionId],
     );
-    const inputHistoryEntries = useInputHistoryStore(React.useCallback((state) => {
-        const entries = selectInputHistoryEntries(state, inputHistoryIdentity);
-        return entries.length === 0 ? EMPTY_INPUT_HISTORY_ENTRIES : entries;
-    }, [inputHistoryIdentity]));
+    const inputHistoryEntries = useInputHistoryStore(React.useCallback(
+        (state) => selectInputHistoryEntries(state, inputHistoryIdentity),
+        [inputHistoryIdentity],
+    ));
+    // Session scope also reads the visible transcript, so sessions older than
+    // the persisted history still recall their prompts.
+    const transcriptPrompts = useUserMessageHistory(currentSessionId ?? '');
     const historyValues = React.useMemo(
-        () => mapInputHistoryEntriesToValues(inputHistoryEntries),
-        [inputHistoryEntries],
+        () => (inputHistoryScope === 'session'
+            ? mergeSessionInputHistory(transcriptPrompts, inputHistoryEntries)
+            : mapInputHistoryEntriesToValues(inputHistoryEntries)),
+        [inputHistoryEntries, inputHistoryScope, transcriptPrompts],
     );
     const messageHistoryIdentity = React.useMemo(
         () => buildInputHistoryNavigatorIdentity(inputHistoryScope, inputHistoryIdentity),