Fix multiline zsh fzf history handoff (CORE-3811)

app/assets/bundled/bootstrap/zsh_body.sh

@@ -709,15 +709,31 @@ if [[ -z $WARP_BOOTSTRAPPED ]]; then
     BUFFER=""
   }
   zle -N warp_report_input
+  function warp_select_fzf_history_entry () {
+    emulate -L zsh
+    setopt extendedglob pipefail
+
+    local selected=""
+    selected="$(fc -rl 1 \
+      | command -p awk '{ cmd=$0; sub(/^[ \t]*[0-9]+\**[ \t]+/, "", cmd); if (!seen[cmd]++) print $0 }' \
+      | fzf --nth=2.. --with-nth=2.. --scheme=history --tiebreak=index +m)"
+    local ret=$?
+    local -a mbegin mend match
+    REPLY=""
+    if [[ "$selected" == [[:blank:]]#(#b)(<->)(#B)(  |\* )* ]] \
+      && (( ${+history[${match[1]}]} )); then
+      REPLY="${history[${match[1]}]}"
+    fi
+    return $ret
+  }
 
   # Runs the shell's own ctrl-r history widget as a foreground command.
   function warp_run_external_ctrl_r_widget () {
     local result=""
     case "$_WARP_EXTERNAL_CTRL_R_WIDGET" in
       fzf-history-widget)
-        result="$(fc -rl 1 \
-          | command -p awk '{ cmd=$0; sub(/^[ \t]*[0-9]+\**[ \t]+/, "", cmd); if (!seen[cmd]++) print cmd }' \
-          | fzf --scheme=history --tiebreak=index +m)"
+        warp_select_fzf_history_entry
+        result="$REPLY"
         ;;
       atuin-search|atuin-search-viins|atuin-search-vicmd|_atuin_search_widget)
         # atuin writes its TUI to stdout; under plain command substitution that's a pipe, and

crates/warp_terminal/src/bootstrap_tests.rs

@@ -1,3 +1,6 @@
+#[cfg(unix)]
+use command::blocking::Command;
+
 use super::*;
 
 struct TestAssetProvider;
@@ -59,6 +62,75 @@ fn test_trims_powershell_specifics() {
     );
 }
 
+#[cfg(unix)]
+#[test]
+fn test_zsh_fzf_history_selection_restores_multiline_entry() {
+    assert_eq!(
+        run_zsh_fzf_history_selection(
+            "echo CORE3811_FIRST\necho CORE3811_SECOND",
+            r"    42  echo CORE3811_FIRST\necho CORE3811_SECOND",
+        ),
+        b"echo CORE3811_FIRST\necho CORE3811_SECOND"
+    );
+}
+
+#[cfg(unix)]
+#[test]
+fn test_zsh_fzf_history_selection_preserves_literal_backslash_n() {
+    assert_eq!(
+        run_zsh_fzf_history_selection(r"printf '%s\n' hi", r"    42  printf '%s\n' hi",),
+        br"printf '%s\n' hi"
+    );
+}
+
+#[cfg(unix)]
+fn run_zsh_fzf_history_selection(canonical_history: &str, listed_history: &str) -> Vec<u8> {
+    const ZSH_BODY: &str = include_str!("../../../app/assets/bundled/bootstrap/zsh_body.sh");
+    const FUNCTION_START: &str = "  function warp_select_fzf_history_entry () {";
+    const FUNCTION_END: &str = "\n  }\n\n  # Runs the shell's own ctrl-r";
+
+    let function_start = ZSH_BODY
+        .find(FUNCTION_START)
+        .expect("fzf history selection function should exist");
+    let function_body = &ZSH_BODY[function_start..];
+    let function_end = function_body
+        .find(FUNCTION_END)
+        .expect("fzf history selection function should have a closing brace")
+        + "\n  }".len();
+    let function_body = &function_body[..function_end];
+    let script = format!(
+        r#"
+{function_body}
+function fc() {{
+  print -r -- "$LISTED_HISTORY"
+}}
+function fzf() {{
+  command cat
+}}
+function run_test() {{
+  local -A history
+  history[42]="$CANONICAL_HISTORY"
+  warp_select_fzf_history_entry
+  print -rn -- "$REPLY"
+}}
+run_test
+"#
+    );
+
+    let output = Command::new("zsh")
+        .args(["-dfc", &script])
+        .env("CANONICAL_HISTORY", canonical_history)
+        .env("LISTED_HISTORY", listed_history)
+        .output()
+        .expect("zsh should run the fzf history selection fixture");
+    assert!(
+        output.status.success(),
+        "zsh fixture failed: {}",
+        String::from_utf8_lossy(&output.stderr)
+    );
+    output.stdout
+}
+
 fn decode_script(bytes: &[u8]) -> &str {
     std::str::from_utf8(bytes).expect("should not fail to decode")
 }