repl: add block-based history navigation

When --experimental-repl-enhancements is enabled, the Up and Down
arrow keys now navigate between history entries as whole blocks
instead of moving line-by-line within a recalled multiline entry.

Previously, recalling a multiline function from history and pressing
Up would move the cursor within that entry's lines before advancing
to the previous history entry. With this change, Up/Down always jump
directly to the previous/next history entry, matching the behavior
of Ctrl-P/Ctrl-N.

Fixes: #48146
Signed-off-by: hemanth <hemanth.hm@gmail.com>

Author: hemanth

doc/api/cli.md

@@ -1390,8 +1390,8 @@ added: REPLACEME
 > Stability: 1 - Experimental
 
 Enable experimental REPL enhancements including inline syntax highlighting,
-auto-indentation, and function signature hints. See the
-[REPL][] documentation for details.
+auto-indentation, function signature hints, and block-based history
+navigation. See the [REPL][] documentation for details.
 
 ### `--experimental-sea-config`
 

doc/api/repl.md

@@ -498,6 +498,22 @@ inspector protocol to safely extract function signatures without side
 effects. Signature hints require the `preview` option to be enabled and
 the inspector to be available.
 
+### Block-based history navigation
+
+<!-- YAML
+added: REPLACEME
+-->
+
+> Stability: 1 - Experimental
+
+When the `--experimental-repl-enhancements` flag is enabled, pressing the
+Up and Down arrow keys navigates between history entries as whole blocks.
+Without this flag, pressing Up within a recalled multiline entry first moves
+the cursor through the entry's lines before advancing to the previous history
+entry. With the flag enabled, Up/Down always jump directly to the
+previous/next history entry, making it easy to recall multiline functions
+and code blocks.
+
 ## Class: `REPLServer`
 
 <!-- YAML

lib/repl.js

@@ -175,6 +175,8 @@ const {
   kMultilinePrompt,
   kAddNewLineOnTTY,
   kLastCommandErrored,
+  kHistoryPrev,
+  kHistoryNext,
 } = require('internal/readline/interface');
 
 // Lazy-loaded.
@@ -967,7 +969,20 @@ class REPLServer extends Interface {
         clearPreview(key);
         clearSignatureHint();
         if (!reverseSearch(d, key)) {
-          ttyWrite(d, key);
+          // When enhancements are enabled, Up/Down navigate history in
+          // blocks rather than moving line-by-line within a recalled
+          // multiline entry.  This makes arrow-key history navigation
+          // behave like Ctrl-P / Ctrl-N (see issue #48146).
+          if (experimentalREPLEnhancements &&
+              (key.name === 'up' || key.name === 'down')) {
+            if (key.name === 'up') {
+              self[kHistoryPrev]();
+            } else {
+              self[kHistoryNext]();
+            }
+          } else {
+            ttyWrite(d, key);
+          }
           const showCompletionPreview = key.name !== 'escape';
           showPreview(showCompletionPreview);
           // Show signature hint when user types '('.