diff --git a/CHANGELOG.md b/CHANGELOG.md
index 0adccf6..0ee578a 100644
--- a/CHANGELOG.md
+++ b/CHANGELOG.md
@@ -1,5 +1,6 @@
 # NEXT
 
+- add `(lookup-file)` message to notify editor of file lookups
 - fix TeX build date to use SOURCE_DATE_EPOCH if set, otherwise falling back to
   the current date (previously hardcoded to Feb 8, 2025).
 - fix zealous JSON escaping
diff --git a/EDITOR-PROTOCOL.md b/EDITOR-PROTOCOL.md
index 2eb25f7..4b5180f 100644
--- a/EDITOR-PROTOCOL.md
+++ b/EDITOR-PROTOCOL.md
@@ -209,3 +209,14 @@ The paths are printed relative to the root file. They might be non-existent on t
 Right now, this is implemented by hooking into SyncTeX:
 - only text files are tracked (not graphics)
 - the indices printed are the SyncTex input indices; they should be attributed no other meaning than being monotonic and useful to detect backtracking occurrences
+
+### File lookups
+
+```
+(lookup-file kind status "path")
+```
+
+Output by TeXpresso when it tries to look up a file.
+- `kind`: either `read` or `write`.
+- `status`: either `successful` or `failed`.
+- `path`: the path to the file.
diff --git a/Makefile b/Makefile
index c435c28..9be3c6c 100644
--- a/Makefile
+++ b/Makefile
@@ -18,7 +18,6 @@ all:
 	@echo "# Or:"
 	@echo "#   build/texpresso -texlive test/simple.tex"
 	@echo "#   build/texpresso -tectonic test/simple.tex"
-	@echo "#"
 
 common:
 	$(MAKE) -C src/common
@@ -110,4 +109,7 @@ test-stream:
 test-stream-pipe:
 	test/test_stream.sh
 
-.PHONY: all dev clean config texpresso common texpresso-xetex re2c compile_commands.json fill-tectonic-cache test-texlive test-tectonic test-texpresso test-stream test-stream-pipe test-open-base64
+test-request-file:
+	bash test/test-request-file.sh
+
+.PHONY: all dev clean config texpresso common texpresso-xetex re2c compile_commands.json fill-tectonic-cache test-texlive test-tectonic test-texpresso test-stream test-stream-pipe test-open-base64 test-request-file
diff --git a/emacs/texpresso.el b/emacs/texpresso.el
index 979c7ad..af91d03 100644
--- a/emacs/texpresso.el
+++ b/emacs/texpresso.el
@@ -319,6 +319,8 @@ standard output. This function interprets one of these."
 
      ((eq tag 'input-file))
 
+     ((eq tag 'lookup-file))
+
      (t (message "Unknown message in texpresso output: %S" expr)))))
 
 (defun texpresso--stdout-filter (process text)
diff --git a/src/frontend/editor.c b/src/frontend/editor.c
index dac5b1d..184bc42 100644
--- a/src/frontend/editor.c
+++ b/src/frontend/editor.c
@@ -586,3 +586,24 @@ void editor_notify_file_opened(int index, const char *path, int len)
     case EDITOR_JSON: fprintf(stdout, "\"]\n"); break;
   }
 }
+
+void editor_notify_lookup(const char *path, int len, bool read, bool success)
+{
+  const char *kind = read ? "read" : "write";
+  const char *status = success ? "successful" : "failed";
+  switch (protocol)
+  {
+    case EDITOR_SEXP:
+      fprintf(stdout, "(lookup-file %s %s \"", kind, status);
+      break;
+    case EDITOR_JSON:
+      fprintf(stdout, "[\"lookup-file\", \"%s\", \"%s\", \"", kind, status);
+      break;
+  }
+  output_data_string(stdout, path, len);
+  switch (protocol)
+  {
+    case EDITOR_SEXP: fprintf(stdout, "\")\n"); break;
+    case EDITOR_JSON: fprintf(stdout, "\"]\n"); break;
+  }
+}
diff --git a/src/frontend/editor.h b/src/frontend/editor.h
index 6aef93f..025faed 100644
--- a/src/frontend/editor.h
+++ b/src/frontend/editor.h
@@ -136,5 +136,6 @@ void editor_flush(void);
 void editor_synctex(const char *dirname, const char *basename, int basename_len, int line, int column);
 void editor_reset_sync(void);
 void editor_notify_file_opened(int index, const char *path, int len);
+void editor_notify_lookup(const char *path, int len, bool read, bool success);
 
 #endif  // EDITOR_H_
diff --git a/src/frontend/engine_tex.c b/src/frontend/engine_tex.c
index 7651017..0850c84 100644
--- a/src/frontend/engine_tex.c
+++ b/src/frontend/engine_tex.c
@@ -496,6 +496,7 @@ static void answer_query(fz_context *ctx, struct tex_engine *self, query_t *q)
             log_fileentry(ctx, self->log, e);
             record_seen(self, e, INT_MAX, q->time);
             a.tag = A_PASS;
+            editor_notify_lookup(q->open.path, strlen(q->open.path), q->tag == Q_OPRD, false);
             channel_write_answer(self->c, p->fd, &a);
             break;
           }
@@ -529,6 +530,7 @@ static void answer_query(fz_context *ctx, struct tex_engine *self, query_t *q)
                 log_fileentry(ctx, self->log, e);
                 record_seen(self, e, INT_MAX, q->time);
                 a.tag = A_PASS;
+                editor_notify_lookup(q->open.path, strlen(q->open.path), q->tag == Q_OPRD, false);
                 channel_write_answer(self->c, p->fd, &a);
                 break;
               }
@@ -620,6 +622,7 @@ static void answer_query(fz_context *ctx, struct tex_engine *self, query_t *q)
       int n = strlen(q->open.path);
       a.open.path_len = n;
       a.tag = A_OPEN;
+      editor_notify_lookup(q->open.path, n, q->tag == Q_OPRD, true);
       memmove(channel_get_buffer(self->c, n), q->open.path, n);
       channel_write_answer(self->c, p->fd, &a);
       break;
diff --git a/src/frontend/main.c b/src/frontend/main.c
index cbe436a..658ec0c 100644
--- a/src/frontend/main.c
+++ b/src/frontend/main.c
@@ -1461,7 +1461,9 @@ bool texpresso_main(struct persistent_state *ps)
           break;
       }
     }
-    if (ps->initialize_only)
+    if (ps->initialize_only &&
+        (send(page_count, ui->eng) > 0 ||
+         (send(get_status, ui->eng) == DOC_TERMINATED && stdin_eof)))
     {
       fprintf(stderr, "[info] Initialize mode: terminating engine process\n");
       quit = 1;
diff --git a/test/request-file.tex b/test/request-file.tex
new file mode 100644
index 0000000..4219056
--- /dev/null
+++ b/test/request-file.tex
@@ -0,0 +1,5 @@
+\documentclass[12pt]{article}
+\begin{document}
+Hello.
+\input{texpresso_ci_missing_file.tex}
+\end{document}
diff --git a/test/test-request-file.sh b/test/test-request-file.sh
new file mode 100755
index 0000000..73460b3
--- /dev/null
+++ b/test/test-request-file.sh
@@ -0,0 +1,52 @@
+#!/bin/bash
+# Test request-file: engine requests a missing file via Q_OPRL (non-blocking),
+# test provides the file, engine restarts and processes it successfully.
+set -e
+
+FIFO=$(mktemp -u /tmp/texpresso-fifo-XXXXXX)
+OUTFILE=$(mktemp /tmp/texpresso-out-XXXXXX)
+mkfifo "$FIFO"
+trap 'rm -f "$FIFO" "$OUTFILE"; kill "$PID" 2>/dev/null || true' EXIT
+
+TARGET="texpresso_ci_missing_file.tex"
+
+# Start texpresso in background, reading stdin from FIFO, stdout to file
+SDL_VIDEODRIVER=dummy build/texpresso -test-initialize test/request-file.tex \
+  < "$FIFO" > "$OUTFILE" 2>/dev/null &
+PID=$!
+
+# Open FIFO for writing (unblocks texpresso's stdin)
+exec 3>"$FIFO"
+
+# Wait for request-file for the target file (ignore .aux etc.)
+TIMEOUT=120
+while ! grep -q "request-file \"$TARGET\"" "$OUTFILE" 2>/dev/null; do
+  sleep 0.5
+  TIMEOUT=$((TIMEOUT - 1))
+  if [ $TIMEOUT -le 0 ]; then
+    echo "FAIL: timeout waiting for request-file"
+    echo "stdout contents:"
+    cat "$OUTFILE"
+    exit 1
+  fi
+  if ! kill -0 "$PID" 2>/dev/null; then
+    echo "FAIL: texpresso exited before emitting request-file for $TARGET"
+    echo "stdout contents:"
+    cat "$OUTFILE"
+    exit 1
+  fi
+done
+
+echo "Got request-file for: $TARGET"
+
+# Provide the missing file content
+printf '(open "%s" "Included content.\\n")\n' "$TARGET" >&3
+exec 3>&-
+
+# Wait for texpresso to finish (it exits after page_count > 0 in -test-initialize mode)
+if wait "$PID"; then
+  echo "PASS: request-file test"
+else
+  echo "FAIL: texpresso exited with error"
+  exit 1
+fi