diff --git a/.gitignore b/.gitignore
index aa31b579..6e3cd53c 100644
--- a/.gitignore
+++ b/.gitignore
@@ -3,6 +3,8 @@
 *.log
 *.pdf
 *.dvi
+*.json
+*.fmt
 flamegraph.svg
 perf.data*
 callgrind*
diff --git a/Cargo.lock b/Cargo.lock
index 6d248cef..a60053b6 100644
--- a/Cargo.lock
+++ b/Cargo.lock
@@ -17,6 +17,12 @@ dependencies = [
  "libc",
 ]
 
+[[package]]
+name = "anstyle"
+version = "1.0.0"
+source = "registry+https://github.com/rust-lang/crates.io-index"
+checksum = "41ed9a86bf92ae6580e0a31281f65a1b1d867c0cc68d5346e2ae128dddfa6a7d"
+
 [[package]]
 name = "arrayref"
 version = "0.3.7"
@@ -60,9 +66,9 @@ checksum = "bef38d45163c2f1dde094a7dfd33ccf595c92905c8f8f4fdc18d06fb1037718a"
 
 [[package]]
 name = "bitflags"
-version = "2.3.1"
+version = "2.3.2"
 source = "registry+https://github.com/rust-lang/crates.io-index"
-checksum = "6776fc96284a0bb647b615056fc496d1fe1644a7ab01829818a6d91cae888b84"
+checksum = "6dbe3c979c178231552ecba20214a8272df4e09f232a87aef4320cf06539aded"
 
 [[package]]
 name = "blake2b_simd"
@@ -124,45 +130,49 @@ source = "registry+https://github.com/rust-lang/crates.io-index"
 checksum = "a0610544180c38b88101fecf2dd634b174a62eef6946f84dfc6a7127512b381c"
 dependencies = [
  "bitflags 1.3.2",
- "textwrap 0.11.0",
+ "textwrap",
  "unicode-width",
 ]
 
 [[package]]
 name = "clap"
-version = "3.2.25"
+version = "4.3.4"
 source = "registry+https://github.com/rust-lang/crates.io-index"
-checksum = "4ea181bf566f71cb9a5d17a59e1871af638180a18fb0035c92ae62b705207123"
+checksum = "80672091db20273a15cf9fdd4e47ed43b5091ec9841bf4c6145c9dfbbcae09ed"
 dependencies = [
- "bitflags 1.3.2",
+ "clap_builder",
  "clap_derive",
- "clap_lex",
- "indexmap",
  "once_cell",
- "textwrap 0.16.0",
+]
+
+[[package]]
+name = "clap_builder"
+version = "4.3.4"
+source = "registry+https://github.com/rust-lang/crates.io-index"
+checksum = "c1458a1df40e1e2afebb7ab60ce55c1fa8f431146205aa5f4887e0b111c27636"
+dependencies = [
+ "anstyle",
+ "bitflags 1.3.2",
+ "clap_lex",
 ]
 
 [[package]]
 name = "clap_derive"
-version = "3.2.25"
+version = "4.3.2"
 source = "registry+https://github.com/rust-lang/crates.io-index"
-checksum = "ae6371b8bdc8b7d3959e9cf7b22d4435ef3e79e138688421ec654acf8c81b008"
+checksum = "b8cd2b2a819ad6eec39e8f1d6b53001af1e5469f8c177579cdaeb313115b825f"
 dependencies = [
  "heck",
- "proc-macro-error",
  "proc-macro2",
  "quote",
- "syn 1.0.109",
+ "syn",
 ]
 
 [[package]]
 name = "clap_lex"
-version = "0.2.4"
+version = "0.5.0"
 source = "registry+https://github.com/rust-lang/crates.io-index"
-checksum = "2850f2f5a82cbf437dd5af4d49848fbdfc27c157c3d010345776f952765261c5"
-dependencies = [
- "os_str_bytes",
-]
+checksum = "2da6da31387c7e4ef160ffab6d5e7f00c42626fe39aea70a7b0f1773f7dd6c1b"
 
 [[package]]
 name = "colored"
@@ -256,9 +266,9 @@ dependencies = [
 
 [[package]]
 name = "crossbeam-epoch"
-version = "0.9.14"
+version = "0.9.15"
 source = "registry+https://github.com/rust-lang/crates.io-index"
-checksum = "46bd5f3f85273295a9d14aedfb86f6aadbff6d8f5295c4a9edb08e819dcf5695"
+checksum = "ae211234986c545741a7dc064309f67ee1e5ad243d0e48335adc0484d960bcc7"
 dependencies = [
  "autocfg",
  "cfg-if",
@@ -269,9 +279,9 @@ dependencies = [
 
 [[package]]
 name = "crossbeam-utils"
-version = "0.8.15"
+version = "0.8.16"
 source = "registry+https://github.com/rust-lang/crates.io-index"
-checksum = "3c063cd8cc95f5c377ed0d4b49a4b21f632396ff690e8470c29b3359b346984b"
+checksum = "5a22b2d63d4d1dc0b7f1b6b2747dd0088008a9be28b6ddf0b1e7d335e3037294"
 dependencies = [
  "cfg-if",
 ]
@@ -368,12 +378,6 @@ version = "1.8.2"
 source = "registry+https://github.com/rust-lang/crates.io-index"
 checksum = "eabb4a44450da02c90444cf74558da904edde8fb4e9035a9a6a4e15445af0bd7"
 
-[[package]]
-name = "hashbrown"
-version = "0.12.3"
-source = "registry+https://github.com/rust-lang/crates.io-index"
-checksum = "8a9ee70c43aaf417c914396645a0fa852624801b24ebb7ae78fe8272889ac888"
-
 [[package]]
 name = "heck"
 version = "0.4.1"
@@ -421,16 +425,6 @@ dependencies = [
  "cc",
 ]
 
-[[package]]
-name = "indexmap"
-version = "1.9.3"
-source = "registry+https://github.com/rust-lang/crates.io-index"
-checksum = "bd070e393353796e801d209ad339e89596eb4c8d430d18ede6a1cced8fafbd99"
-dependencies = [
- "autocfg",
- "hashbrown",
-]
-
 [[package]]
 name = "itertools"
 version = "0.10.5"
@@ -448,9 +442,9 @@ checksum = "453ad9f582a441959e5f0d088b02ce04cfe8d51a8eaf077f12ac6d3e94164ca6"
 
 [[package]]
 name = "js-sys"
-version = "0.3.63"
+version = "0.3.64"
 source = "registry+https://github.com/rust-lang/crates.io-index"
-checksum = "2f37a4a5928311ac501dee68b3c7613a1037d0edb30c8e5427bd832d55d1b790"
+checksum = "c5f195fe497f702db0f318b07fdd68edb16955aed830df8363d837542f8f935a"
 dependencies = [
  "wasm-bindgen",
 ]
@@ -480,9 +474,9 @@ dependencies = [
 
 [[package]]
 name = "log"
-version = "0.4.18"
+version = "0.4.19"
 source = "registry+https://github.com/rust-lang/crates.io-index"
-checksum = "518ef76f2f87365916b142844c16d8fefd85039bc5699050210a7778ee1cd1de"
+checksum = "b06a4cde4c0f271a446782e3eff8de789548ce57dbc8eca9292c27f4a42004b4"
 
 [[package]]
 name = "memchr"
@@ -492,9 +486,9 @@ checksum = "2dffe52ecf27772e601905b7522cb4ef790d2cc203488bbd0e2fe85fcb74566d"
 
 [[package]]
 name = "memoffset"
-version = "0.8.0"
+version = "0.9.0"
 source = "registry+https://github.com/rust-lang/crates.io-index"
-checksum = "d61c719bcfbcf5d62b3a09efa6088de8c54bc0bfcd3ea7ae39fcc186108b8de1"
+checksum = "5a634b1c61a95585bd15607c6ab0c4e5b226e695ff2800ba0cdccddf208c406c"
 dependencies = [
  "autocfg",
 ]
@@ -511,7 +505,7 @@ version = "0.2.4"
 source = "registry+https://github.com/rust-lang/crates.io-index"
 checksum = "2c624fa1b7aab6bd2aff6e9b18565cc0363b6d45cbcd7465c9ed5e3740ebf097"
 dependencies = [
- "bitflags 2.3.1",
+ "bitflags 2.3.2",
  "libc",
  "nix",
  "smallstr",
@@ -574,12 +568,6 @@ version = "11.1.3"
 source = "registry+https://github.com/rust-lang/crates.io-index"
 checksum = "0ab1bc2a289d34bd04a330323ac98a1b4bc82c9d9fcb1e66b63caa84da26b575"
 
-[[package]]
-name = "os_str_bytes"
-version = "6.5.0"
-source = "registry+https://github.com/rust-lang/crates.io-index"
-checksum = "ceedf44fb00f2d1984b0bc98102627ce622e083e49a5bacdb3e514fa4238e267"
-
 [[package]]
 name = "paste"
 version = "1.0.12"
@@ -668,35 +656,11 @@ version = "0.2.17"
 source = "registry+https://github.com/rust-lang/crates.io-index"
 checksum = "5b40af805b3121feab8a3c29f04d8ad262fa8e0561883e7653e024ae4479e6de"
 
-[[package]]
-name = "proc-macro-error"
-version = "1.0.4"
-source = "registry+https://github.com/rust-lang/crates.io-index"
-checksum = "da25490ff9892aab3fcf7c36f08cfb902dd3e71ca0f9f9517bea02a73a5ce38c"
-dependencies = [
- "proc-macro-error-attr",
- "proc-macro2",
- "quote",
- "syn 1.0.109",
- "version_check",
-]
-
-[[package]]
-name = "proc-macro-error-attr"
-version = "1.0.4"
-source = "registry+https://github.com/rust-lang/crates.io-index"
-checksum = "a1be40180e52ecc98ad80b184934baf3d0d29f979574e439af5a55274b35f869"
-dependencies = [
- "proc-macro2",
- "quote",
- "version_check",
-]
-
 [[package]]
 name = "proc-macro2"
-version = "1.0.59"
+version = "1.0.60"
 source = "registry+https://github.com/rust-lang/crates.io-index"
-checksum = "6aeca18b86b413c660b781aa319e4e2648a3e6f9eadc9b47e9038e6fe9f3451b"
+checksum = "dec2b086b7a862cf4de201096214fa870344cf922b2b30c167badb3af3195406"
 dependencies = [
  "unicode-ident",
 ]
@@ -871,9 +835,9 @@ checksum = "d29ab0c6d3fc0ee92fe66e2d99f700eab17a8d57d1c1d3b748380fb20baa78cd"
 
 [[package]]
 name = "serde"
-version = "1.0.163"
+version = "1.0.164"
 source = "registry+https://github.com/rust-lang/crates.io-index"
-checksum = "2113ab51b87a539ae008b5c6c02dc020ffa39afd2d83cffcb3f4eb2722cebec2"
+checksum = "9e8c8cf938e98f769bc164923b06dce91cea1751522f46f8466461af04c9027d"
 dependencies = [
  "serde_derive",
 ]
@@ -890,13 +854,13 @@ dependencies = [
 
 [[package]]
 name = "serde_derive"
-version = "1.0.163"
+version = "1.0.164"
 source = "registry+https://github.com/rust-lang/crates.io-index"
-checksum = "8c805777e3930c8883389c602315a24224bcc738b63905ef87cd1420353ea93e"
+checksum = "d9735b638ccc51c28bf6914d90a2e9725b377144fc612c49a611fddd1b631d68"
 dependencies = [
  "proc-macro2",
  "quote",
- "syn 2.0.18",
+ "syn",
 ]
 
 [[package]]
@@ -937,17 +901,6 @@ version = "1.1.0"
 source = "registry+https://github.com/rust-lang/crates.io-index"
 checksum = "a2eb9349b6444b326872e140eb1cf5e7c522154d69e7a0ffb0fb81c06b37543f"
 
-[[package]]
-name = "syn"
-version = "1.0.109"
-source = "registry+https://github.com/rust-lang/crates.io-index"
-checksum = "72b64191b275b66ffe2469e8af2c1cfe3bafa67b529ead792a6d0160888b4237"
-dependencies = [
- "proc-macro2",
- "quote",
- "unicode-ident",
-]
-
 [[package]]
 name = "syn"
 version = "2.0.18"
@@ -976,10 +929,12 @@ dependencies = [
 name = "texcraft"
 version = "0.1.0"
 dependencies = [
- "clap 3.2.25",
+ "clap 4.3.4",
  "colored",
  "performance",
  "rand",
+ "rmp-serde",
+ "serde_json",
  "texlang-core",
  "texlang-stdlib",
 ]
@@ -1038,12 +993,6 @@ dependencies = [
  "unicode-width",
 ]
 
-[[package]]
-name = "textwrap"
-version = "0.16.0"
-source = "registry+https://github.com/rust-lang/crates.io-index"
-checksum = "222a222a5bfe1bba4a77b45ec488a741b3cb8872e5e499451fd7d0129c9c7c3d"
-
 [[package]]
 name = "thiserror"
 version = "1.0.40"
@@ -1061,7 +1010,7 @@ checksum = "f9456a42c5b0d803c8cd86e73dd7cc9edd429499f37a3550d286d5e86720569f"
 dependencies = [
  "proc-macro2",
  "quote",
- "syn 2.0.18",
+ "syn",
 ]
 
 [[package]]
@@ -1110,12 +1059,6 @@ version = "0.1.10"
 source = "registry+https://github.com/rust-lang/crates.io-index"
 checksum = "c0edd1e5b14653f783770bce4a4dabb4a5108a5370a5f5d8cfe8710c361f6c8b"
 
-[[package]]
-name = "version_check"
-version = "0.9.4"
-source = "registry+https://github.com/rust-lang/crates.io-index"
-checksum = "49874b5167b65d7193b8aba1567f5c7d93d001cafc34600cee003eda787e483f"
-
 [[package]]
 name = "walkdir"
 version = "2.3.3"
@@ -1140,9 +1083,9 @@ checksum = "9c8d87e72b64a3b4db28d11ce29237c246188f4f51057d65a7eab63b7987e423"
 
 [[package]]
 name = "wasm-bindgen"
-version = "0.2.86"
+version = "0.2.87"
 source = "registry+https://github.com/rust-lang/crates.io-index"
-checksum = "5bba0e8cb82ba49ff4e229459ff22a191bbe9a1cb3a341610c9c33efc27ddf73"
+checksum = "7706a72ab36d8cb1f80ffbf0e071533974a60d0a308d01a5d0375bf60499a342"
 dependencies = [
  "cfg-if",
  "wasm-bindgen-macro",
@@ -1150,24 +1093,24 @@ dependencies = [
 
 [[package]]
 name = "wasm-bindgen-backend"
-version = "0.2.86"
+version = "0.2.87"
 source = "registry+https://github.com/rust-lang/crates.io-index"
-checksum = "19b04bc93f9d6bdee709f6bd2118f57dd6679cf1176a1af464fca3ab0d66d8fb"
+checksum = "5ef2b6d3c510e9625e5fe6f509ab07d66a760f0885d858736483c32ed7809abd"
 dependencies = [
  "bumpalo",
  "log",
  "once_cell",
  "proc-macro2",
  "quote",
- "syn 2.0.18",
+ "syn",
  "wasm-bindgen-shared",
 ]
 
 [[package]]
 name = "wasm-bindgen-macro"
-version = "0.2.86"
+version = "0.2.87"
 source = "registry+https://github.com/rust-lang/crates.io-index"
-checksum = "14d6b024f1a526bb0234f52840389927257beb670610081360e5a03c5df9c258"
+checksum = "dee495e55982a3bd48105a7b947fd2a9b4a8ae3010041b9e0faab3f9cd028f1d"
 dependencies = [
  "quote",
  "wasm-bindgen-macro-support",
@@ -1175,28 +1118,28 @@ dependencies = [
 
 [[package]]
 name = "wasm-bindgen-macro-support"
-version = "0.2.86"
+version = "0.2.87"
 source = "registry+https://github.com/rust-lang/crates.io-index"
-checksum = "e128beba882dd1eb6200e1dc92ae6c5dbaa4311aa7bb211ca035779e5efc39f8"
+checksum = "54681b18a46765f095758388f2d0cf16eb8d4169b639ab575a8f5693af210c7b"
 dependencies = [
  "proc-macro2",
  "quote",
- "syn 2.0.18",
+ "syn",
  "wasm-bindgen-backend",
  "wasm-bindgen-shared",
 ]
 
 [[package]]
 name = "wasm-bindgen-shared"
-version = "0.2.86"
+version = "0.2.87"
 source = "registry+https://github.com/rust-lang/crates.io-index"
-checksum = "ed9d5b4305409d1fc9482fee2d7f9bcbf24b3972bf59817ef757e23982242a93"
+checksum = "ca6ad05a4870b2bf5fe995117d3728437bd27d7cd5f06f13c17443ef369775a1"
 
 [[package]]
 name = "web-sys"
-version = "0.3.63"
+version = "0.3.64"
 source = "registry+https://github.com/rust-lang/crates.io-index"
-checksum = "3bdd9ef4e984da1187bf8110c5cf5b845fbc87a23602cdf912386a76fcd3a7c2"
+checksum = "9b85cbef8c220a6abc02aefd892dfc0fc23afb1c6a426316ec33253a3877249b"
 dependencies = [
  "js-sys",
  "wasm-bindgen",
diff --git a/bin/Cargo.toml b/bin/Cargo.toml
index a3b0e1b5..00be462e 100644
--- a/bin/Cargo.toml
+++ b/bin/Cargo.toml
@@ -12,10 +12,12 @@ name = "randtex"
 path = "src/randtex.rs"
 
 [dependencies]
-clap = {version="3.0.0-beta.5", default-features=false, features=["std", "derive"]}
+clap = {version="4.3.3", default-features=false, features=["std", "derive"]}
 colored = "2"
 rand = "0.8.4"
+rmp-serde = {version="^1.0"}
+serde_json = {version="1.0"} 
 
 texlang-core = { path = "../crates/texlang-core" }
-texlang-stdlib = { path = "../crates/texlang-stdlib", features = ["repl"]}
+texlang-stdlib = { path = "../crates/texlang-stdlib", features = ["repl", "serde"]}
 performance = {path = "../performance"}
diff --git a/bin/src/texcraft.rs b/bin/src/texcraft.rs
index a5522a33..1603e944 100644
--- a/bin/src/texcraft.rs
+++ b/bin/src/texcraft.rs
@@ -1,9 +1,10 @@
 use clap::Parser;
 use colored::Colorize;
-use std::collections::HashMap;
+use std::ffi::OsStr;
 use std::fs;
 use std::path::PathBuf;
 use texlang_core::*;
+use texlang_stdlib::job;
 use texlang_stdlib::repl;
 use texlang_stdlib::script;
 use texlang_stdlib::StdLibState;
@@ -16,6 +17,10 @@ use texlang_stdlib::StdLibState;
 #[derive(Parser)]
 #[clap(version)]
 struct Cli {
+    /// Path to a format file
+    #[arg(long)]
+    format_file: Option<PathBuf>,
+
     #[clap(subcommand)]
     sub_command: SubCommand,
 }
@@ -44,14 +49,16 @@ struct Run {
 
 fn main() {
     let args: Cli = Cli::parse();
+    let is_repl = matches!(args.sub_command, SubCommand::Repl);
+    let mut vm = new_vm(args.format_file, is_repl);
     let result = match args.sub_command {
-        SubCommand::Doc(d) => doc(d.name),
+        SubCommand::Doc(d) => doc(&vm, d.name),
         SubCommand::Repl => {
-            repl();
+            repl(&mut vm);
             Ok(())
         }
         SubCommand::Run(run_args) => {
-            let result = run(run_args.file_path);
+            let result = run(&mut vm, run_args.file_path);
             if let Err(err) = result {
                 println!["{err}"];
                 std::process::exit(1);
@@ -65,10 +72,11 @@ fn main() {
     }
 }
 
-fn run(mut path: PathBuf) -> Result<(), Box<error::Error>> {
+fn run(vm: &mut vm::VM<StdLibState>, mut path: PathBuf) -> Result<(), Box<error::Error>> {
     if path.extension().is_none() {
         path.set_extension("tex");
     }
+    vm.state.job.set_job_name(&path);
     let source_code = match fs::read_to_string(&path) {
         Ok(source_code) => source_code,
         Err(err) => {
@@ -76,19 +84,17 @@ fn run(mut path: PathBuf) -> Result<(), Box<error::Error>> {
             std::process::exit(1);
         }
     };
-    let mut vm = new_vm();
     // The only error possible is input stack size exceeded, which can't be hit.
     // TODO: the external VM method shouldn't error
     let _ = vm.push_source(path.to_string_lossy().to_string(), source_code);
-    script::run_and_write(&mut vm, Box::new(std::io::stdout()))?;
+    script::run_and_write(vm, Box::new(std::io::stdout()))?;
     Ok(())
 }
 
-fn repl() {
+fn repl(vm: &mut vm::VM<StdLibState>) {
     println!("{}\n", REPL_START.trim());
-    let mut vm = new_repl_vm();
     repl::run::run(
-        &mut vm,
+        vm,
         repl::RunOptions {
             prompt: "tex> ",
             help: REPL_HELP,
@@ -125,9 +131,7 @@ Tips
 Website: https://texcraft.dev
 ";
 
-fn doc(cs_name: Option<String>) -> Result<(), String> {
-    let vm = new_vm();
-
+fn doc(vm: &vm::VM<StdLibState>, cs_name: Option<String>) -> Result<(), String> {
     match cs_name {
         None => {
             let mut cs_names = Vec::new();
@@ -175,21 +179,7 @@ fn doc(cs_name: Option<String>) -> Result<(), String> {
     }
 }
 
-fn new_vm() -> Box<vm::VM<StdLibState>> {
-    vm::VM::<StdLibState>::new(initial_built_ins())
-}
-
-fn new_repl_vm() -> Box<vm::VM<StdLibState>> {
-    let mut m = initial_built_ins();
-    m.insert("doc", repl::get_doc());
-    m.insert("help", repl::get_help());
-    m.insert("exit", repl::get_exit());
-    m.insert("quit", repl::get_exit());
-    m.insert("q", repl::get_exit());
-    vm::VM::<StdLibState>::new(m)
-}
-
-fn initial_built_ins() -> HashMap<&'static str, command::BuiltIn<StdLibState>> {
+fn new_vm(format_file_path: Option<PathBuf>, repl: bool) -> Box<vm::VM<StdLibState>> {
     let mut m = StdLibState::all_initial_built_ins();
     m.insert("par", script::get_par());
     m.insert("newline", script::get_newline());
@@ -197,5 +187,27 @@ fn initial_built_ins() -> HashMap<&'static str, command::BuiltIn<StdLibState>> {
         "\\",
         command::Command::Character(token::Value::Other('\\')).into(),
     );
-    m
+    if repl {
+        m.insert("doc", repl::get_doc());
+        m.insert("help", repl::get_help());
+        m.insert("exit", repl::get_exit());
+        m.insert("quit", repl::get_exit());
+        m.insert("q", repl::get_exit());
+    } else {
+        m.insert("dump", job::get_dump());
+    }
+
+    match format_file_path {
+        None => vm::VM::<StdLibState>::new(m),
+        Some(path) => {
+            let format_file = std::fs::read(&path).unwrap();
+            if path.extension().map(OsStr::to_str) == Some(Some("json")) {
+                let mut deserializer = serde_json::Deserializer::from_slice(&format_file);
+                vm::VM::deserialize(&mut deserializer, m)
+            } else {
+                let mut deserializer = rmp_serde::decode::Deserializer::from_read_ref(&format_file);
+                vm::VM::deserialize(&mut deserializer, m)
+            }
+        }
+    }
 }
diff --git a/crates/texcraft-stdext/src/serde_tools.rs b/crates/texcraft-stdext/src/serde_tools.rs
index ec88ae0e..f9c07d81 100644
--- a/crates/texcraft-stdext/src/serde_tools.rs
+++ b/crates/texcraft-stdext/src/serde_tools.rs
@@ -30,3 +30,28 @@ where
     let a: [T; N] = v.try_into().unwrap();
     Ok(a)
 }
+
+/// Function that serializes strings
+///
+/// This is intended for use with serde derive's
+/// `#[serde(serialize_with = "path")]` field attribute.
+pub fn serialize_str<T: AsRef<str>, S>(input: T, serializer: S) -> Result<S::Ok, S::Error>
+where
+    S: serde::Serializer,
+{
+    let s: &str = input.as_ref();
+    s.serialize(serializer)
+}
+
+/// Function that deserializes reference counted constant strings
+///
+/// This is intended for use with serde derive's
+/// `#[serde(deserialize_with = "path")]` field attribute.
+pub fn deserialize_rc_str<'de, D>(deserializer: D) -> Result<std::rc::Rc<str>, D::Error>
+where
+    D: serde::Deserializer<'de>,
+{
+    // TODO: should probably use Cow<> here to support not coping the string
+    let s = String::deserialize(deserializer)?;
+    Ok(s.into())
+}
diff --git a/crates/texcraft-stdext/src/str.rs b/crates/texcraft-stdext/src/str.rs
index 695b6016..ffa0afe7 100644
--- a/crates/texcraft-stdext/src/str.rs
+++ b/crates/texcraft-stdext/src/str.rs
@@ -2,7 +2,17 @@
 ///
 /// This iterator is an alternative to the standard library's [Chars](std::str::Chars).
 /// This iterator has shared ownership of the string being iterated over and avoids lifetime issues.
+#[cfg_attr(feature = "serde", derive(serde::Serialize, serde::Deserialize))]
 pub struct OwningChars {
+    // TODO: we don't need to serialize the full string, we just nneed to serialize
+    // everything after pos.
+    #[cfg_attr(
+        feature = "serde",
+        serde(
+            serialize_with = "crate::serde_tools::serialize_str",
+            deserialize_with = "crate::serde_tools::deserialize_rc_str"
+        )
+    )]
     s: std::rc::Rc<str>,
     pos: usize,
 }
diff --git a/crates/texlang-core/src/command/map.rs b/crates/texlang-core/src/command/map.rs
index 2db8e2c4..c16fd4a5 100644
--- a/crates/texlang-core/src/command/map.rs
+++ b/crates/texlang-core/src/command/map.rs
@@ -81,6 +81,10 @@ impl<S> Map<S> {
         }
     }
 
+    pub fn initial_built_ins(&self) -> &HashMap<token::CsName, BuiltIn<S>> {
+        &self.initial_built_ins
+    }
+
     pub fn get_command_slow(&self, name: &token::CsName) -> Option<BuiltIn<S>> {
         let command = match self.get_command(name) {
             None => return None,
@@ -318,6 +322,7 @@ impl<'a> SerializableMap<'a> {
     pub(crate) fn finish_deserialization<S>(
         self,
         initial_built_ins: HashMap<token::CsName, BuiltIn<S>>,
+        interner: &token::CsNameInterner,
     ) -> Map<S> {
         let macros: Vec<Rc<texmacro::Macro>> = self
             .macros
@@ -332,7 +337,15 @@ impl<'a> SerializableMap<'a> {
                 |(cs_name, serialized_command): (token::CsName, &SerializableCommand)| {
                     let command = match serialized_command {
                         SerializableCommand::BuiltIn(cs_name) => {
-                            initial_built_ins.get(cs_name).unwrap().cmd.clone()
+                            match initial_built_ins.get(cs_name) {
+                                None => {
+                                    panic!(
+                                        "unknown control sequence {:?}",
+                                        interner.resolve(*cs_name)
+                                    )
+                                }
+                                Some(cmd) => cmd.cmd.clone(),
+                            }
                         }
                         SerializableCommand::VariableArrayStatic(cs_name, index) => {
                             match &initial_built_ins.get(cs_name).unwrap().cmd {
diff --git a/crates/texlang-core/src/error/display.rs b/crates/texlang-core/src/error/display.rs
index b22b2c9e..15850a92 100644
--- a/crates/texlang-core/src/error/display.rs
+++ b/crates/texlang-core/src/error/display.rs
@@ -7,7 +7,7 @@ pub fn format_error(f: &mut std::fmt::Formatter<'_>, err: &error::Error) -> std:
     let (error_line, immediate_command) = match root.kind() {
         error::Kind::Token(s) => (s, stack.last()),
         error::Kind::EndOfInput(s) => (s, stack.last()),
-        error::Kind::InvalidCodePath => (&stack.last().unwrap().trace, None),
+        error::Kind::FailedPrecondition => (&stack.last().unwrap().trace, None),
     };
 
     let line = PrimaryLine {
@@ -211,7 +211,7 @@ fn fmt_source_code_trace(
         .with_content(format!(
             "{} {}:{}:{}",
             ">>>".bright_cyan().bold(),
-            s.file_name,
+            s.file_name.display(),
             s.line_number,
             s.index + 1
         ))
@@ -256,7 +256,7 @@ fn fmt_source_code_trace_light(
     let prefix = format!(
         "{}{}:{}:{}",
         " ".repeat(indent),
-        s.file_name,
+        s.file_name.display(),
         s.line_number,
         s.index + 1
     );
diff --git a/crates/texlang-core/src/error/mod.rs b/crates/texlang-core/src/error/mod.rs
index b4036862..78205f4e 100644
--- a/crates/texlang-core/src/error/mod.rs
+++ b/crates/texlang-core/src/error/mod.rs
@@ -69,7 +69,7 @@ pub struct PropagatedError {
 pub enum Kind<'a> {
     Token(&'a trace::SourceCodeTrace),
     EndOfInput(&'a trace::SourceCodeTrace),
-    InvalidCodePath,
+    FailedPrecondition,
 }
 
 pub trait TexError: std::fmt::Debug {
@@ -97,7 +97,9 @@ pub trait TexError: std::fmt::Debug {
                 }
             }
             Kind::EndOfInput(_) => "input ended here".into(),
-            Kind::InvalidCodePath => todo!(),
+            Kind::FailedPrecondition => {
+                "failed precondition error while running this command".into()
+            }
         }
     }
 }
@@ -198,6 +200,45 @@ impl TexError for SimpleEndOfInputError {
     }
 }
 
+#[derive(Debug)]
+pub struct SimpleFailedPreconditionError {
+    pub title: String,
+    pub text_notes: Vec<String>,
+}
+
+impl SimpleFailedPreconditionError {
+    /// Create a new simple failed precondition error.
+    pub fn new<T: AsRef<str>>(title: T) -> Self {
+        Self {
+            title: title.as_ref().into(),
+            text_notes: vec![],
+        }
+    }
+
+    pub fn with_note<T: Into<String>>(mut self, note: T) -> Self {
+        self.text_notes.push(note.into());
+        self
+    }
+}
+
+impl TexError for SimpleFailedPreconditionError {
+    fn kind(&self) -> Kind {
+        Kind::FailedPrecondition
+    }
+
+    fn title(&self) -> String {
+        self.title.clone()
+    }
+
+    fn notes(&self) -> Vec<display::Note> {
+        let mut notes = vec![];
+        for text_note in &self.text_notes {
+            notes.push(text_note.into())
+        }
+        notes
+    }
+}
+
 #[derive(Debug)]
 pub struct UndefinedCommandError {
     pub trace: trace::SourceCodeTrace,
diff --git a/crates/texlang-core/src/token/lexer.rs b/crates/texlang-core/src/token/lexer.rs
index 163c310d..e4694432 100644
--- a/crates/texlang-core/src/token/lexer.rs
+++ b/crates/texlang-core/src/token/lexer.rs
@@ -38,10 +38,12 @@ impl CatCodeFn for std::collections::HashMap<char, CatCode> {
 }
 
 /// The Texlang lexer
+#[cfg_attr(feature = "serde", derive(serde::Serialize, serde::Deserialize))]
 pub struct Lexer {
     raw_lexer: RawLexer,
     trim_next_whitespace: bool,
     // We read control sequence names into a shared buffer to avoid allocating for each one.
+    #[cfg_attr(feature = "serde", serde(skip))]
     buffer: String,
 }
 
@@ -170,6 +172,7 @@ struct RawToken {
     trace_key: trace::Key,
 }
 
+#[cfg_attr(feature = "serde", derive(serde::Serialize, serde::Deserialize))]
 struct RawLexer {
     iter: OwningChars,
     trace_key_range: trace::KeyRange,
diff --git a/crates/texlang-core/src/token/mod.rs b/crates/texlang-core/src/token/mod.rs
index b88a92c9..71c6ec35 100644
--- a/crates/texlang-core/src/token/mod.rs
+++ b/crates/texlang-core/src/token/mod.rs
@@ -146,6 +146,7 @@ impl Token {
         self.value
     }
 
+    #[inline]
     pub fn trace_key(&self) -> trace::Key {
         self.trace_key
     }
diff --git a/crates/texlang-core/src/token/trace.rs b/crates/texlang-core/src/token/trace.rs
index 8b23297c..25e4ffb1 100644
--- a/crates/texlang-core/src/token/trace.rs
+++ b/crates/texlang-core/src/token/trace.rs
@@ -36,6 +36,7 @@
 use crate::token::{CsNameInterner, Token, Value};
 use std::collections::BTreeMap;
 use std::ops::Bound::Included;
+use std::path::PathBuf;
 
 /// Key attached to tokens to enable tracing them.
 ///
@@ -51,6 +52,7 @@ impl Key {
 }
 
 /// Range of free keys that may be assigned to tokens.
+#[cfg_attr(feature = "serde", derive(serde::Serialize, serde::Deserialize))]
 pub struct KeyRange {
     next: u32,
     limit: u32,
@@ -99,7 +101,7 @@ impl KeyRange {
 #[derive(Debug, PartialEq, Eq)]
 pub struct SourceCodeTrace {
     /// Name of the file this token came from.
-    pub file_name: String,
+    pub file_name: PathBuf,
     /// Content of the line this token came from.
     pub line_content: String,
     /// Number of the line within the file, starting at 1.
@@ -115,6 +117,7 @@ pub struct SourceCodeTrace {
 
 /// Data structure that records information for token tracing
 #[derive(Default)]
+#[cfg_attr(feature = "serde", derive(serde::Serialize, serde::Deserialize))]
 pub struct Tracer {
     checkpoints: BTreeMap<u32, Checkpoint>,
     next_key: u32,
@@ -135,7 +138,7 @@ impl Tracer {
     pub fn register_source_code(
         &mut self,
         token: Option<Token>,
-        file_name: String,
+        file_name: PathBuf,
         source_code: &str,
     ) -> KeyRange {
         let len = match u32::try_from(source_code.len()) {
@@ -250,8 +253,9 @@ impl Tracer {
     }
 }
 
+#[cfg_attr(feature = "serde", derive(serde::Serialize, serde::Deserialize))]
 enum Checkpoint {
-    SourceCode { file_name: String, content: String },
+    SourceCode { file_name: PathBuf, content: String },
 }
 
 #[cfg(test)]
@@ -260,7 +264,7 @@ mod tests {
 
     #[test]
     fn one_source_code() {
-        let file_name = "input.tex".to_string();
+        let file_name: PathBuf = "input.tex".into();
         let line_1 = "hël".to_string();
         let line_2 = "wor\\cömmand".to_string();
         let line_3 = "hël".to_string();
@@ -403,17 +407,17 @@ mod tests {
         let mut tracer: Tracer = Default::default();
         let interner: CsNameInterner = Default::default();
 
-        let file_1 = "a.tex".to_string();
+        let file_1: PathBuf = "a.tex".into();
         let file_1_content = "a".to_string();
         let mut range = tracer.register_source_code(None, file_1.clone(), &file_1_content);
         tokens.push(Token::new_letter('a', range.next()));
 
-        let file_2 = "b.tex".to_string();
+        let file_2: PathBuf = "b.tex".into();
         let file_2_content = "b".to_string();
         let mut range = tracer.register_source_code(None, file_2.clone(), &file_2_content);
         tokens.push(Token::new_letter('b', range.next()));
 
-        let file_3 = "c.tex".to_string();
+        let file_3: PathBuf = "c.tex".into();
         let file_3_content = "c".to_string();
         let mut range = tracer.register_source_code(None, file_3.clone(), &file_3_content);
         tokens.push(Token::new_letter('c', range.next()));
diff --git a/crates/texlang-core/src/variable.rs b/crates/texlang-core/src/variable.rs
index d9d715aa..01251517 100644
--- a/crates/texlang-core/src/variable.rs
+++ b/crates/texlang-core/src/variable.rs
@@ -384,7 +384,7 @@ impl<S> Command<S> {
     }
 
     /// Create a new getter provider.
-    /// 
+    ///
     /// A getter provider is a variable command that is not intended to be invoked directly
     /// In fact, the variable command will panic the program if it is invoked.
     /// Instead the provider is included in a VM's initial commands so that
@@ -396,7 +396,11 @@ impl<S> Command<S> {
         ref_fn: RefFn<S, T>,
         ref_mut_fn: MutRefFn<S, T>,
     ) -> Command<S> {
-        SupportedType::new_command(ref_fn, ref_mut_fn, Some(IndexResolver::Dynamic(|_, _|{ panic!() })))
+        SupportedType::new_command(
+            ref_fn,
+            ref_mut_fn,
+            Some(IndexResolver::Dynamic(|_, _| panic!())),
+        )
     }
 
     /// Create a new variable using the provided getters.
diff --git a/crates/texlang-core/src/vm/mod.rs b/crates/texlang-core/src/vm/mod.rs
index 2f2e10e8..60c6ac31 100644
--- a/crates/texlang-core/src/vm/mod.rs
+++ b/crates/texlang-core/src/vm/mod.rs
@@ -20,6 +20,7 @@ use crate::token::Value;
 use crate::variable;
 use std::cell::RefCell;
 use std::collections::HashMap;
+use std::path::PathBuf;
 use std::rc::Rc;
 use texcraft_stdext::collections::groupingmap;
 
@@ -221,6 +222,11 @@ pub trait FileSystem {
     ///
     /// This is implemented by [std::fs::read_to_string].
     fn read_to_string(&self, path: &std::path::Path) -> std::io::Result<String>;
+
+    /// Write a slice of bytes to a file.
+    ///
+    /// This is implemented by [std::fs::write].
+    fn write_bytes(&self, path: &std::path::Path, contents: &[u8]) -> std::io::Result<()>;
 }
 
 struct RealFileSystem;
@@ -229,6 +235,9 @@ impl FileSystem for RealFileSystem {
     fn read_to_string(&self, path: &std::path::Path) -> std::io::Result<String> {
         std::fs::read_to_string(path)
     }
+    fn write_bytes(&self, path: &std::path::Path, contents: &[u8]) -> std::io::Result<()> {
+        std::fs::write(path, contents)
+    }
 }
 
 /// Implementations of this trait may be used as the state in a Texlang VM.
@@ -354,7 +363,7 @@ impl<S: TexlangState> VM<S> {
     ///
     /// TeX input source code is organized as a stack.
     /// Pushing source code onto the stack will mean it is executed first.
-    pub fn push_source<T1: Into<String>, T2: Into<String>>(
+    pub fn push_source<T1: Into<PathBuf>, T2: Into<String>>(
         &mut self,
         file_name: T1,
         source_code: T2,
@@ -426,6 +435,12 @@ impl<S> VM<S> {
 }
 
 /// Parts of the VM that are private.
+// We have serde(bound="") because otherwise serde tries to put a `Default` bound on S.
+#[cfg_attr(
+    feature = "serde",
+    derive(::serde::Serialize, ::serde::Deserialize),
+    serde(bound = "")
+)]
 struct Internal<S> {
     // The sources form a stack. We store the top element directly on the VM
     // for performance reasons.
@@ -436,8 +451,11 @@ struct Internal<S> {
 
     tracer: trace::Tracer,
 
-    token_buffers: std::collections::BinaryHeap<TokenBuffer>, // add a #[skip]
+    #[cfg_attr(feature = "serde", serde(skip))]
+    token_buffers: std::collections::BinaryHeap<TokenBuffer>,
 
+    // Groups are handled manually in (de)serialization because we need to have special logic that uses the command map
+    #[cfg_attr(feature = "serde", serde(skip))]
     groups: Vec<variable::RestoreValues<S>>,
 }
 
@@ -457,7 +475,7 @@ impl<S: TexlangState> Internal<S> {
     fn push_source(
         &mut self,
         token: Option<Token>,
-        file_name: String,
+        file_name: PathBuf,
         source_code: String,
     ) -> Result<(), Box<error::Error>> {
         let source_code: std::rc::Rc<str> = source_code.into();
@@ -505,6 +523,7 @@ impl<S> Internal<S> {
     }
 }
 
+#[cfg_attr(feature = "serde", derive(::serde::Serialize, ::serde::Deserialize))]
 struct Source {
     expansions: Vec<Token>,
     root: lexer::Lexer,
diff --git a/crates/texlang-core/src/vm/serde.rs b/crates/texlang-core/src/vm/serde.rs
index faa8e934..abab2fc0 100644
--- a/crates/texlang-core/src/vm/serde.rs
+++ b/crates/texlang-core/src/vm/serde.rs
@@ -8,7 +8,7 @@ use std::rc::Rc;
 struct SerializableVM<'a, S> {
     state: &'a S,
     commands_map: &'a command::Map<S>,
-    interner: &'a token::CsNameInterner,
+    internal: &'a vm::Internal<S>,
 }
 
 impl<'a, S> SerializableVM<'a, S> {
@@ -16,7 +16,7 @@ impl<'a, S> SerializableVM<'a, S> {
         Self {
             state: &vm.state,
             commands_map: &vm.commands_map,
-            interner: &vm.internal.cs_name_interner,
+            internal: &vm.internal,
         }
     }
 }
@@ -35,26 +35,26 @@ impl<State: serde::Serialize> Serialize for vm::VM<State> {
 struct DeserializedVM<'a, S> {
     state: S,
     commands_map: command::map::SerializableMap<'a>,
-    interner: token::CsNameInterner,
+    internal: vm::Internal<S>,
 }
 
 fn finish_deserialization<S>(
-    #[allow(clippy::boxed_local)] deserialized: Box<DeserializedVM<'_, S>>,
+    #[allow(clippy::boxed_local)] mut deserialized: Box<DeserializedVM<'_, S>>,
     initial_built_ins: HashMap<&str, command::BuiltIn<S>>,
 ) -> Box<vm::VM<S>> {
-    let mut internal = vm::Internal::new(deserialized.interner);
     let initial_built_ins = initial_built_ins
         .into_iter()
         .map(|(key, value)| {
-            let cs_name = internal.cs_name_interner.get_or_intern(key);
+            let cs_name = deserialized.internal.cs_name_interner.get_or_intern(key);
             (cs_name, value)
         })
         .collect();
+    let commands_map = deserialized
+        .commands_map
+        .finish_deserialization(initial_built_ins, &deserialized.internal.cs_name_interner);
     Box::new(vm::VM {
         state: deserialized.state,
-        commands_map: deserialized
-            .commands_map
-            .finish_deserialization(initial_built_ins),
+        commands_map,
         file_system: Box::new(super::RealFileSystem {}),
         terminal: Rc::new(RefCell::new(std::io::stderr())),
         log_file: Rc::new(RefCell::new(std::io::sink())),
@@ -65,7 +65,7 @@ fn finish_deserialization<S>(
                 None
             }
         },
-        internal,
+        internal: deserialized.internal,
     })
 }
 
diff --git a/crates/texlang-core/src/vm/streams.rs b/crates/texlang-core/src/vm/streams.rs
index bf99f429..0debbb02 100644
--- a/crates/texlang-core/src/vm/streams.rs
+++ b/crates/texlang-core/src/vm/streams.rs
@@ -1,3 +1,5 @@
+use std::path::PathBuf;
+
 use super::TexlangState;
 use crate::token::trace;
 use crate::token::Token;
@@ -224,13 +226,14 @@ impl<S> ExpansionInput<S> {
         unsafe { &mut *(vm as *mut vm::VM<S> as *mut ExpansionInput<S>) }
     }
 }
+
 impl<S: TexlangState> ExpansionInput<S> {
     /// Push source code to the front of the input stream.
     #[inline]
     pub fn push_source(
         &mut self,
         token: Token,
-        file_name: String,
+        file_name: PathBuf,
         source_code: String,
     ) -> Result<(), Box<error::Error>> {
         self.0
@@ -239,7 +242,19 @@ impl<S: TexlangState> ExpansionInput<S> {
             .internal
             .push_source(Some(token), file_name, source_code)
     }
+
+    pub fn push_string_tokens(&mut self, token: Token, s: &str) {
+        let trace_key = token.trace_key();
+        for c in s.chars().rev() {
+            let token = match c {
+                ' ' => token::Token::new_space(' ', trace_key),
+                _ => token::Token::new_letter(c, trace_key),
+            };
+            self.expansions_mut().push(token);
+        }
+    }
 }
+
 impl<S> ExpansionInput<S> {
     #[inline]
     pub fn unexpanded(&mut self) -> &mut UnexpandedStream<S> {
diff --git a/crates/texlang-stdlib/Cargo.toml b/crates/texlang-stdlib/Cargo.toml
index dd484c8a..897c11fb 100644
--- a/crates/texlang-stdlib/Cargo.toml
+++ b/crates/texlang-stdlib/Cargo.toml
@@ -22,8 +22,8 @@ texlang-core = { path = "../texlang-core" }
 # Nice terminal output.
 colored = "2"
 
-serde_json = {version="1.0", optional = true}
 serde = {version="^1.0", optional = true}
+serde_json = {version="1.0", optional = true}
 rmp-serde = {version="^1.0", optional = true}
 
 [features]
diff --git a/crates/texlang-stdlib/src/alloc.rs b/crates/texlang-stdlib/src/alloc.rs
index e8d52a73..5362733a 100644
--- a/crates/texlang-stdlib/src/alloc.rs
+++ b/crates/texlang-stdlib/src/alloc.rs
@@ -106,7 +106,7 @@ fn singleton_mut_ref_fn<S: HasComponent<Component>>(
 }
 
 /// Return a getter provider for the `\newInt` command.
-/// 
+///
 /// The initial commands for a VM must include this command in order for
 ///     the allocation component to be serializable.
 pub fn get_newint_getter_provider<S: HasComponent<Component>>() -> command::BuiltIn<S> {
@@ -175,7 +175,7 @@ fn array_element_mut_ref_fn<S: HasComponent<Component>>(
 }
 
 /// Return a getter provider for the `\newIntArray` command.
-/// 
+///
 /// The initial commands for a VM must include this command in order to support
 ///     the allocation component to be serializable.
 pub fn get_newintarray_getter_provider<S: HasComponent<Component>>() -> command::BuiltIn<S> {
@@ -183,7 +183,8 @@ pub fn get_newintarray_getter_provider<S: HasComponent<Component>>() -> command:
         array_element_ref_fn,
         array_element_mut_ref_fn,
         variable::IndexResolver::Dynamic(resolve),
-    ).into()
+    )
+    .into()
 }
 
 #[cfg(test)]
@@ -209,7 +210,10 @@ mod test {
             ("newInt", get_newint()),
             ("newInt_getter_provider_\u{0}", get_newint_getter_provider()),
             ("newIntArray", get_newintarray()),
-            ("newIntArray_getter_provider_\u{0}", get_newintarray_getter_provider()),
+            (
+                "newIntArray_getter_provider_\u{0}",
+                get_newintarray_getter_provider(),
+            ),
             ("the", get_the()),
         ])
     }
diff --git a/crates/texlang-stdlib/src/io.rs b/crates/texlang-stdlib/src/io.rs
index d1a3f41f..0f063d71 100644
--- a/crates/texlang-stdlib/src/io.rs
+++ b/crates/texlang-stdlib/src/io.rs
@@ -17,7 +17,7 @@ fn input_fn<S: TexlangState>(
 ) -> Result<Vec<token::Token>, Box<command::Error>> {
     let file_location = FileLocation::parse(input)?;
     let (file_path, source_code) = read_file(input_token, input.vm(), file_location, ".tex")?;
-    input.push_source(input_token, file_path, source_code)?;
+    input.push_source(input_token, file_path.into(), source_code)?;
     Ok(Vec::new())
 }
 
diff --git a/crates/texlang-stdlib/src/job.rs b/crates/texlang-stdlib/src/job.rs
new file mode 100644
index 00000000..b5bc3eb4
--- /dev/null
+++ b/crates/texlang-stdlib/src/job.rs
@@ -0,0 +1,155 @@
+use std::{
+    collections::HashMap,
+    ffi::OsString,
+    path::{Path, PathBuf},
+};
+use texlang_core::traits::*;
+use texlang_core::*;
+
+#[cfg_attr(feature = "serde", derive(serde::Serialize, serde::Deserialize))]
+pub struct Component {
+    #[cfg_attr(feature = "serde", serde(skip))]
+    job_name: Option<PathBuf>,
+    default_job_name: PathBuf,
+    dump_format: i32,
+    dump_validate: i32,
+    #[cfg_attr(feature = "serde", serde(skip))]
+    num_dumps: usize,
+}
+
+impl Default for Component {
+    fn default() -> Self {
+        Self {
+            job_name: None,
+            default_job_name: "jobname".into(),
+            dump_format: 0,
+            dump_validate: 0,
+            num_dumps: 0,
+        }
+    }
+}
+
+impl Component {
+    pub fn job_name(&self) -> &Path {
+        match &self.job_name {
+            None => &self.default_job_name,
+            Some(job_name) => job_name,
+        }
+    }
+
+    // TODO: this should be called after the first \input.
+    // Probably should add a hook to the VM for this case.
+    // TODO: maybe this should be bundled with \input
+    /// Set the job name based on the provided file path.
+    pub fn set_job_name(&mut self, file_path: &Path) {
+        if let Some(file_stem) = file_path.file_stem() {
+            self.job_name = Some(file_stem.into())
+        }
+    }
+}
+
+/// Get the `\jobname` primitive.
+pub fn get_jobname<S: HasComponent<Component>>() -> command::BuiltIn<S> {
+    command::BuiltIn::new_expansion(|token, input| {
+        let job_name: String = input
+            .state()
+            .component()
+            .job_name()
+            .to_string_lossy()
+            .into();
+        input.push_string_tokens(token, &job_name);
+        Ok(vec![])
+    })
+}
+
+/// Get the `\dump` primitive.
+#[cfg(feature = "serde")]
+pub fn get_dump<S: HasComponent<Component> + serde::Serialize + serde::de::DeserializeOwned>(
+) -> command::BuiltIn<S> {
+    command::BuiltIn::new_execution(dump_primitive_fn)
+}
+
+#[cfg(feature = "serde")]
+fn dump_primitive_fn<
+    S: HasComponent<Component> + serde::Serialize + serde::de::DeserializeOwned,
+>(
+    _: token::Token,
+    input: &mut vm::ExecutionInput<S>,
+) -> command::Result<()> {
+    let component = input.state().component();
+    let mut job_name: OsString = component.job_name().into();
+    let num_dumps = component.num_dumps;
+    if num_dumps > 0 {
+        job_name.push(format!["-{}", num_dumps + 1]);
+    }
+    let mut output_file: PathBuf = job_name.into();
+    output_file.set_extension(if component.dump_format == 0 {
+        "fmt"
+    } else {
+        "fmt.json"
+    });
+
+    // TODO: error handle all these serialization errors.
+    let serialized = match component.dump_format {
+        0 => rmp_serde::encode::to_vec(input.vm()).unwrap(),
+        1 => serde_json::to_vec_pretty(input.vm()).unwrap(),
+        i => {
+            return Err(error::SimpleFailedPreconditionError::new(format![
+                r"\dumpFormat has invalid value {i}",
+            ])
+            .with_note(r"\dumpFormat must be either 0 (serialize with message pack) or 1 (serialize with json)")
+            .into())
+        }
+    };
+
+    if component.dump_validate != 0 {
+        let initial_built_ins: HashMap<&str, command::BuiltIn<S>> = input
+            .vm()
+            .commands_map
+            .initial_built_ins()
+            .iter()
+            .map(|(cs_name, command)| {
+                (
+                    input.vm().cs_name_interner().resolve(*cs_name).unwrap(),
+                    command.clone(),
+                )
+            })
+            .collect();
+        match component.dump_format {
+            0 => {
+                let mut deserializer = rmp_serde::decode::Deserializer::from_read_ref(&serialized);
+                vm::VM::<S>::deserialize(&mut deserializer, initial_built_ins);
+            }
+            1 => {
+                let mut deserializer = serde_json::Deserializer::from_slice(&serialized);
+                vm::VM::<S>::deserialize(&mut deserializer, initial_built_ins);
+            }
+            _ => unreachable!(),
+        };
+    }
+
+    // TODO: error handle file write
+    input
+        .vm()
+        .file_system
+        .write_bytes(&output_file, &serialized)
+        .unwrap();
+    input.state_mut().component_mut().num_dumps += 1;
+    Ok(())
+}
+
+pub fn get_dumpformat<S: HasComponent<Component>>() -> command::BuiltIn<S> {
+    variable::Command::new_singleton(
+        |state: &S, _| &state.component().dump_format,
+        |state: &mut S, _| &mut state.component_mut().dump_format,
+    )
+    .into()
+}
+
+pub fn get_dumpvalidate<S: HasComponent<Component>>() -> command::BuiltIn<S> {
+    variable::Command::new_singleton(
+        |state: &S, _| &state.component().dump_validate,
+        |state: &mut S, _| &mut state.component_mut().dump_validate,
+    )
+    .into()
+}
diff --git a/crates/texlang-stdlib/src/lib.rs b/crates/texlang-stdlib/src/lib.rs
index 6308e1c3..06a95693 100644
--- a/crates/texlang-stdlib/src/lib.rs
+++ b/crates/texlang-stdlib/src/lib.rs
@@ -19,6 +19,7 @@ pub mod conditional;
 pub mod def;
 pub mod expansion;
 pub mod io;
+pub mod job;
 pub mod math;
 pub mod prefix;
 pub mod registers;
@@ -38,6 +39,7 @@ pub struct StdLibState {
     alloc: alloc::Component,
     catcode: catcode::Component,
     conditional: conditional::Component,
+    pub job: job::Component,
     prefix: prefix::Component,
     registers: registers::Component<i32, 32768>,
     repl: repl::Component,
@@ -93,6 +95,8 @@ impl StdLibState {
             ("day", time::get_day()),
             ("def", def::get_def()),
             ("divide", math::get_divide()),
+            ("dumpFormat", job::get_dumpformat()),
+            ("dumpValidate", job::get_dumpvalidate()),
             //
             ("else", conditional::get_else()),
             ("expandafter", expansion::get_expandafter_optimized()),
@@ -110,6 +114,8 @@ impl StdLibState {
             ("iftrue", conditional::get_if_true()),
             ("input", io::get_input()),
             //
+            ("jobname", job::get_jobname()),
+            //
             ("let", alias::get_let()),
             ("long", prefix::get_long()),
             //
@@ -117,9 +123,15 @@ impl StdLibState {
             ("multiply", math::get_multiply()),
             //
             ("newInt", alloc::get_newint()),
-            ("newInt_getter_provider_\u{0}", alloc::get_newint_getter_provider()),
+            (
+                "newInt_getter_provider_\u{0}",
+                alloc::get_newint_getter_provider(),
+            ),
             ("newIntArray", alloc::get_newintarray()),
-            ("newIntArray_getter_provider_\u{0}", alloc::get_newintarray_getter_provider()),
+            (
+                "newIntArray_getter_provider_\u{0}",
+                alloc::get_newintarray_getter_provider(),
+            ),
             ("noexpand", expansion::get_noexpand()),
             //
             ("or", conditional::get_or()),
@@ -147,6 +159,7 @@ implement_has_component![
     (alloc::Component, alloc),
     (catcode::Component, catcode),
     (conditional::Component, conditional),
+    (job::Component, job),
     (prefix::Component, prefix),
     (registers::Component<i32, 32768>, registers),
     (repl::Component, repl),
@@ -265,7 +278,7 @@ mod tests {
             r"\def\else{}\ifodd 2 \else should be skipped \fi",
             r""
         )),
-        serde_tests((serde_sanity_check, r"\def\HW{Hello World} ", r"\HW"),),
+        serde_tests((serde_sanity, r"\def\HW{Hello World} ", r"\HW"),),
     ];
 
     #[test]
diff --git a/crates/texlang-stdlib/src/registers.rs b/crates/texlang-stdlib/src/registers.rs
index 4e16fc77..f91ec64e 100644
--- a/crates/texlang-stdlib/src/registers.rs
+++ b/crates/texlang-stdlib/src/registers.rs
@@ -13,7 +13,7 @@ pub struct Component<T, const N: usize>(
     // We currently box the values because putting them directly on the stack causes the
     // message pack decoder to stack overflow. It's a pity that we have to pay a runtime
     // cost due to this, and it would be nice to fix the issue another way.
-    Box<[T; N]>
+    Box<[T; N]>,
 );
 
 #[cfg(feature = "serde")]
diff --git a/crates/texlang-stdlib/src/testing.rs b/crates/texlang-stdlib/src/testing.rs
index ac69173f..5b4a7a0b 100644
--- a/crates/texlang-stdlib/src/testing.rs
+++ b/crates/texlang-stdlib/src/testing.rs
@@ -216,7 +216,9 @@ pub fn run_serde_test<S>(
     output_1_1.append(&mut output_1_2);
 
     let mut vm_2 = initialize_vm(&options);
-    let output_2 = crate::testing::execute_source_code(&mut vm_2,format!["{input_1}{input_2}"], &options).unwrap();
+    let output_2 =
+        crate::testing::execute_source_code(&mut vm_2, format!["{input_1}{input_2}"], &options)
+            .unwrap();
 
     compare_output(output_1_1, &vm_1, output_2, &vm_2)
 }
@@ -312,6 +314,9 @@ impl vm::FileSystem for InMemoryFileSystem {
             Some(content) => Ok(content.clone()),
         }
     }
+    fn write_bytes(&self, _: &std::path::Path, _: &[u8]) -> std::io::Result<()> {
+        unimplemented!()
+    }
 }
 
 impl InMemoryFileSystem {