diff --git a/CMakeLists.txt b/CMakeLists.txt
index 862bd6117..281455fed 100644
--- a/CMakeLists.txt
+++ b/CMakeLists.txt
@@ -123,8 +123,7 @@ set(FISH_SRCS
     src/pager.cpp src/parse_execution.cpp src/parse_tree.cpp src/parse_util.cpp
     src/parser.cpp src/parser_keywords.cpp src/path.cpp src/postfork.cpp
     src/proc.cpp src/re.cpp src/reader.cpp src/screen.cpp
-    src/signals.cpp src/tinyexpr.cpp
-    src/trace.cpp src/utf8.cpp
+    src/signals.cpp src/tinyexpr.cpp src/utf8.cpp
     src/wcstringutil.cpp src/wgetopt.cpp src/wildcard.cpp
     src/wutil.cpp src/fds.cpp src/rustffi.cpp
 )
diff --git a/fish-rust/build.rs b/fish-rust/build.rs
index c1553ed75..5ffbbabd1 100644
--- a/fish-rust/build.rs
+++ b/fish-rust/build.rs
@@ -39,6 +39,7 @@ fn main() -> miette::Result<()> {
         "src/timer.rs",
         "src/tokenizer.rs",
         "src/topic_monitor.rs",
+        "src/trace.rs",
         "src/util.rs",
         "src/wait_handle.rs",
         "src/builtins/shared.rs",
diff --git a/fish-rust/src/ffi.rs b/fish-rust/src/ffi.rs
index 997227f1f..deebfe238 100644
--- a/fish-rust/src/ffi.rs
+++ b/fish-rust/src/ffi.rs
@@ -56,6 +56,7 @@ include_cpp! {
     generate!("valid_var_name_char")
 
     generate!("get_flog_file_fd")
+    generate!("log_extra_to_flog_file")
 
     generate!("parse_util_unescape_wildcards")
 
diff --git a/fish-rust/src/lib.rs b/fish-rust/src/lib.rs
index e6e8f0947..e0af59d0d 100644
--- a/fish-rust/src/lib.rs
+++ b/fish-rust/src/lib.rs
@@ -28,6 +28,7 @@ mod ffi_init;
 mod ffi_tests;
 mod flog;
 mod future_feature_flags;
+mod global_safety;
 mod job_group;
 mod locale;
 mod nix;
@@ -42,6 +43,7 @@ mod threads;
 mod timer;
 mod tokenizer;
 mod topic_monitor;
+mod trace;
 mod util;
 mod wait_handle;
 mod wchar;
diff --git a/fish-rust/src/trace.rs b/fish-rust/src/trace.rs
new file mode 100644
index 000000000..0f554b5f0
--- /dev/null
+++ b/fish-rust/src/trace.rs
@@ -0,0 +1,74 @@
+use crate::{
+    common::{escape_string, EscapeStringStyle},
+    ffi::{self, parser_t, wcharz_t},
+    global_safety::RelaxedAtomicBool,
+    wchar::{self, wstr, L},
+    wchar_ffi::WCharToFFI,
+};
+
+#[cxx::bridge]
+mod trace_ffi {
+    extern "C++" {
+        include!("wutil.h");
+        include!("parser.h");
+        type wcharz_t = super::wcharz_t;
+        type parser_t = super::parser_t;
+    }
+
+    extern "Rust" {
+        fn trace_set_enabled(do_enable: bool);
+        fn trace_enabled(parser: &parser_t) -> bool;
+        #[cxx_name = "trace_argv"]
+        fn trace_argv_ffi(parser: &parser_t, command: wcharz_t, args: &Vec<wcharz_t>);
+    }
+}
+
+static DO_TRACE: RelaxedAtomicBool = RelaxedAtomicBool::new(false);
+
+pub fn trace_set_enabled(do_enable: bool) {
+    DO_TRACE.store(do_enable);
+}
+
+/// return whether tracing is enabled.
+pub fn trace_enabled(parser: &parser_t) -> bool {
+    let ld = parser.ffi_libdata_pod_const();
+    if ld.suppress_fish_trace {
+        return false;
+    }
+    DO_TRACE.load()
+}
+
+/// Trace an "argv": a list of arguments where the first is the command.
+// Allow the `&Vec` parameter as this function only exists temporarily for the FFI
+#[allow(clippy::ptr_arg)]
+fn trace_argv_ffi(parser: &parser_t, command: wcharz_t, args: &Vec<wcharz_t>) {
+    let command: wchar::WString = command.into();
+    let args: Vec<wchar::WString> = args.iter().map(Into::into).collect();
+    let args_ref: Vec<&wstr> = args.iter().map(wchar::WString::as_utfstr).collect();
+    trace_argv(parser, command.as_utfstr(), &args_ref);
+}
+
+pub fn trace_argv(parser: &parser_t, command: &wstr, args: &[&wstr]) {
+    // Format into a string to prevent interleaving with flog in other threads.
+    // Add the + prefix.
+    let mut trace_text = L!("-").repeat(parser.blocks_size() - 1);
+    trace_text.push('>');
+
+    if !command.is_empty() {
+        trace_text.push(' ');
+        trace_text.push_utfstr(command);
+    }
+    for arg in args {
+        trace_text.push(' ');
+        trace_text.push_utfstr(&escape_string(arg, EscapeStringStyle::default()));
+    }
+    trace_text.push('\n');
+    ffi::log_extra_to_flog_file(&trace_text.to_ffi());
+}
+
+/// Convenience helper to trace a single string if tracing is enabled.
+pub fn trace_if_enabled(parser: &parser_t, command: &wstr, args: &[&wstr]) {
+    if trace_enabled(parser) {
+        trace_argv(parser, command, args);
+    }
+}
diff --git a/src/builtin.cpp b/src/builtin.cpp
index ed9d86566..3bf424c8e 100644
--- a/src/builtin.cpp
+++ b/src/builtin.cpp
@@ -59,6 +59,7 @@
 #include "cxx.h"
 #include "cxxgen.h"
 #include "fallback.h"  // IWYU pragma: keep
+#include "ffi.h"
 #include "flog.h"
 #include "io.h"
 #include "null_terminated_array.h"
@@ -565,13 +566,8 @@ static maybe_t<RustBuiltin> try_get_rust_builtin(const wcstring &cmd) {
 
 static maybe_t<int> builtin_run_rust(parser_t &parser, io_streams_t &streams,
                                      const wcstring_list_t &argv, RustBuiltin builtin) {
-    ::rust::Vec<wcharz_t> rust_argv;
-    for (const wcstring &arg : argv) {
-        rust_argv.emplace_back(arg.c_str());
-    }
-
     int status_code;
-    bool update_status = rust_run_builtin(parser, streams, rust_argv, builtin, status_code);
+    bool update_status = rust_run_builtin(parser, streams, to_rust_string_vec(argv), builtin, status_code);
     if (update_status) {
         return status_code;
     } else {
diff --git a/src/env_dispatch.cpp b/src/env_dispatch.cpp
index c7659d2b5..1b8efe5c3 100644
--- a/src/env_dispatch.cpp
+++ b/src/env_dispatch.cpp
@@ -47,7 +47,7 @@
 #include "reader.h"
 #include "screen.h"
 #include "termsize.h"
-#include "trace.h"
+#include "trace.rs.h"
 #include "wcstringutil.h"
 #include "wutil.h"
 
diff --git a/src/exec.cpp b/src/exec.cpp
index 57a666fea..de025deb3 100644
--- a/src/exec.cpp
+++ b/src/exec.cpp
@@ -7,6 +7,7 @@
 #include <ctype.h>
 #include <errno.h>
 #include <fcntl.h>
+#include "trace.rs.h"
 #ifdef HAVE_SIGINFO_H
 #include <siginfo.h>
 #endif
@@ -33,6 +34,7 @@
 #include "exec.h"
 #include "fallback.h"  // IWYU pragma: keep
 #include "fds.h"
+#include "ffi.h"
 #include "flog.h"
 #include "function.h"
 #include "global_safety.h"
@@ -48,7 +50,7 @@
 #include "reader.h"
 #include "redirection.h"
 #include "timer.rs.h"
-#include "trace.h"
+#include "trace.rs.h"
 #include "wcstringutil.h"
 #include "wutil.h"  // IWYU pragma: keep
 
@@ -827,9 +829,7 @@ static launch_result_t exec_process_in_job(parser_t &parser, process_t *p,
 
     // Maybe trace this process.
     // TODO: 'and' and 'or' will not show.
-    if (trace_enabled(parser)) {
-        trace_argv(parser, nullptr, p->argv());
-    }
+    trace_if_enabled(parser, L"", p->argv());
 
     // The IO chain for this process.
     io_chain_t process_net_io_chain = block_io;
diff --git a/src/ffi.h b/src/ffi.h
index 711ece232..9dea99f97 100644
--- a/src/ffi.h
+++ b/src/ffi.h
@@ -2,6 +2,7 @@
 #include <memory>
 
 #include "cxx.h"
+#include "trace.rs.h"
 #if INCLUDE_RUST_HEADERS
 // For some unknown reason, the definition of rust::Box is in this particular header:
 #include "parse_constants.rs.h"
@@ -13,3 +14,19 @@ inline std::shared_ptr<T> box_to_shared_ptr(rust::Box<T> &&value) {
     std::shared_ptr<T> shared(ptr, [](T *ptr) { rust::Box<T>::from_raw(ptr); });
     return shared;
 }
+
+inline static rust::Vec<wcharz_t> to_rust_string_vec(const wcstring_list_t &strings) {
+    rust::Vec<wcharz_t> rust_strings;
+    rust_strings.reserve(strings.size());
+    for (const wcstring &string : strings) {
+        rust_strings.emplace_back(string.c_str());
+    }
+    return rust_strings;
+}
+
+inline static void trace_if_enabled(const parser_t &parser, wcharz_t command,
+                                    const wcstring_list_t &args = {}) {
+    if (trace_enabled(parser)) {
+        trace_argv(parser, command, to_rust_string_vec(args));
+    }
+}
diff --git a/src/parse_execution.cpp b/src/parse_execution.cpp
index e67d2031e..a8ed65c4f 100644
--- a/src/parse_execution.cpp
+++ b/src/parse_execution.cpp
@@ -42,7 +42,7 @@
 #include "reader.h"
 #include "timer.rs.h"
 #include "tokenizer.h"
-#include "trace.h"
+#include "trace.rs.h"
 #include "wildcard.h"
 #include "wutil.h"
 
@@ -390,6 +390,7 @@ end_execution_reason_t parse_execution_context_t::run_function_statement(
     if (result != end_execution_reason_t::ok) {
         return result;
     }
+
     trace_if_enabled(*parser, L"function", arguments);
     null_output_stream_t outs;
     string_output_stream_t errs;
@@ -537,7 +538,8 @@ end_execution_reason_t parse_execution_context_t::run_switch_statement(
     }
 
     end_execution_reason_t result = end_execution_reason_t::ok;
-    if (trace_enabled(*parser)) trace_argv(*parser, L"switch", {switch_value_expanded});
+
+    trace_if_enabled(*parser, L"switch", {switch_value_expanded});
     block_t *sb = parser->push_block(block_t::switch_block());
 
     // Expand case statements.
diff --git a/src/parser.cpp b/src/parser.cpp
index 89a18fdf2..d5d2e5ed0 100644
--- a/src/parser.cpp
+++ b/src/parser.cpp
@@ -514,6 +514,7 @@ job_t *parser_t::job_get_from_pid(int64_t pid, size_t &job_pos) const {
 library_data_pod_t *parser_t::ffi_libdata_pod() { return &library_data; }
 
 job_t *parser_t::ffi_job_get_from_pid(int pid) const { return job_get_from_pid(pid); }
+const library_data_pod_t &parser_t::ffi_libdata_pod_const() const { return library_data; }
 
 profile_item_t *parser_t::create_profile_item() {
     if (g_profiling_active) {
diff --git a/src/parser.h b/src/parser.h
index 661e3c54f..4a78b1d03 100644
--- a/src/parser.h
+++ b/src/parser.h
@@ -383,6 +383,8 @@ class parser_t : public std::enable_shared_from_this<parser_t> {
     /// Return the list of blocks. The first block is at the top.
     const std::deque<block_t> &blocks() const { return block_list; }
 
+    size_t blocks_size() const { return block_list.size(); }
+
     /// Get the list of jobs.
     job_list_t &jobs() { return job_list; }
     const job_list_t &jobs() const { return job_list; }
@@ -500,6 +502,7 @@ class parser_t : public std::enable_shared_from_this<parser_t> {
     RustFFIJobList ffi_jobs() const;
     library_data_pod_t *ffi_libdata_pod();
     job_t *ffi_job_get_from_pid(int pid) const;
+    const library_data_pod_t &ffi_libdata_pod_const() const;
 
     /// autocxx junk.
     bool ffi_has_funtion_block() const;
diff --git a/src/trace.cpp b/src/trace.cpp
deleted file mode 100644
index 8fa2cfe63..000000000
--- a/src/trace.cpp
+++ /dev/null
@@ -1,43 +0,0 @@
-#include "config.h"  // IWYU pragma: keep
-
-#include "trace.h"
-
-#include <deque>
-#include <string>
-
-#include "common.h"
-#include "flog.h"
-#include "parser.h"
-
-static bool do_trace = false;
-
-void trace_set_enabled(bool do_enable) { do_trace = do_enable; }
-
-bool trace_enabled(const parser_t &parser) {
-    const auto &ld = parser.libdata();
-    if (ld.suppress_fish_trace) return false;
-    return do_trace;
-}
-
-/// Trace an "argv": a list of arguments where the first is the command.
-void trace_argv(const parser_t &parser, const wchar_t *command, const wcstring_list_t &argv) {
-    // Format into a string to prevent interleaving with flog in other threads.
-    // Add the + prefix.
-    wcstring trace_text(parser.blocks().size() - 1, L'-');
-    trace_text.push_back(L'>');
-
-    if (command && command[0]) {
-        trace_text.push_back(L' ');
-        trace_text.append(command);
-    }
-    for (const wcstring &arg : argv) {
-        trace_text.push_back(L' ');
-        trace_text.append(escape_string(arg));
-    }
-    trace_text.push_back(L'\n');
-    log_extra_to_flog_file(trace_text);
-}
-
-void trace_if_enabled(const parser_t &parser, const wchar_t *command, const wcstring_list_t &argv) {
-    if (trace_enabled(parser)) trace_argv(parser, command, argv);
-}
diff --git a/src/trace.h b/src/trace.h
deleted file mode 100644
index e891fdbb3..000000000
--- a/src/trace.h
+++ /dev/null
@@ -1,25 +0,0 @@
-/// Support for fish_trace.
-#ifndef FISH_TRACE_H
-#define FISH_TRACE_H
-
-#include "config.h"  // IWYU pragma: keep
-
-#include "common.h"
-
-class parser_t;
-
-/// Trace an "argv": a list of arguments. Each argument is escaped.
-/// If \p command is not null, it is traced first (and not escaped)
-void trace_argv(const parser_t &parser, const wchar_t *command, const wcstring_list_t &argv);
-
-/// \return whether tracing is enabled.
-bool trace_enabled(const parser_t &parser);
-
-/// Enable or disable tracing.
-void trace_set_enabled(bool do_enable);
-
-/// Convenience helper to trace a single string if tracing is enabled.
-void trace_if_enabled(const parser_t &parser, const wchar_t *command,
-                      const wcstring_list_t &argv = {});
-
-#endif