diff --git a/.github/examples/release_language_client_ruby.yaml b/.github/workflows/build-ruby-release.reusable.yaml
similarity index 58%
rename from .github/examples/release_language_client_ruby.yaml
rename to .github/workflows/build-ruby-release.reusable.yaml
index 986928442..b696f26bf 100644
--- a/.github/examples/release_language_client_ruby.yaml
+++ b/.github/workflows/build-ruby-release.reusable.yaml
@@ -1,14 +1,15 @@
 name: Release engine/language_client_ruby
 
 on:
-  workflow_dispatch: {}
+  workflow_call: {}
 
 permissions:
   contents: read
   id-token: write
 
 concurrency:
-  group: ${{ github.workflow }}-${{ github.ref }}
+  # suffix is important to prevent a concurrency deadlock with the calling workflow
+  group: ${{ github.workflow }}-${{ github.ref }}-build-ruby
   cancel-in-progress: true
 
 jobs:
@@ -16,11 +17,19 @@ jobs:
     strategy:
       fail-fast: false
       matrix:
-        platform:
-          - x86_64-linux
-          - aarch64-linux
-          - x86_64-darwin
-          - arm64-darwin
+        _:
+          - platform: x86_64-linux
+            # This is necessary because rb-sys-dock depends on manylinux2014,
+            # which is based on CentOS 7 which is EOL as of July 2024 Once
+            # rake-compiler-dock switches to manylinux_2_28 and rb-sys-dock
+            # picks that up, we can pick their updates up and then drop this.
+            # See https://github.com/oxidize-rb/rb-sys/issues/402 and
+            # https://github.com/rake-compiler/rake-compiler-dock/issues/122
+            # for more details.
+            rb-sys-dock-setup: ./x86-64_linux-setup.sh
+          - platform: aarch64-linux
+          - platform: x86_64-darwin
+          - platform: arm64-darwin
           #- x64-mingw-ucrt
 
     runs-on: ubuntu-latest
@@ -28,11 +37,6 @@ jobs:
       run:
         working-directory: engine/language_client_ruby
     steps:
-      - uses: rubygems/configure-rubygems-credentials@main
-        with:
-          # https://rubygems.org/profile/oidc/api_key_roles/rg_oidc_akr_p6x4xz53qtk948na3bgy
-          role-to-assume: rg_oidc_akr_p6x4xz53qtk948na3bgy
-
       - uses: actions/checkout@v4
 
       - uses: oxidize-rb/actions/setup-ruby-and-rust@main
@@ -65,34 +69,6 @@ jobs:
           echo "RB_SYS_DOCK_CACHE_DIR=$rb_sys_dock_cache_dir" >> $GITHUB_ENV
           echo "rb_sys_version=$rb_sys_version" >> $GITHUB_OUTPUT
 
-      #- name: Setup caching
-      #  uses: actions/cache@v4
-      #  with:
-      #    path: |
-      #      ${{ env.RB_SYS_DOCK_CACHE_DIR }}
-      #      tmp/rb-sys-dock/${{ inputs.platform }}/target
-      #    key: rb-sys-dock-${{ inputs.cache-version }}-${{ inputs.platform }}-${{ hashFiles('**/Gemfile.lock', '**/Cargo.lock') }}
-      #    save-always: ${{ inputs.cache-save-always == 'true' }}
-      #    restore-keys: |
-      #      rb-sys-dock-${{ inputs.cache-version }}-${{ inputs.platform }}-
-
-      #- name: Install cargo-cache
-      #  uses: oxidize-rb/actions/cargo-binstall@v1
-      #  id: install-cargo-cache
-      #  if: inputs.cargo-cache-clean == 'true'
-      #  with:
-      #    crate: cargo-cache
-      #    version: 0.8.3
-      #    strategies: quick-install
-
-      #- name: Clean the cargo cache
-      #  if: inputs.cargo-cache-clean == 'true'
-      #  uses: oxidize-rb/actions/post-run@v1
-      #  with:
-      #    run: cargo-cache --autoclean
-      #    cwd: ${{ inputs.working-directory }}
-      #    always: ${{ inputs.cache-save-always == 'true' }}
-
       - name: Setup rb-sys
         shell: bash
         run: |
@@ -108,35 +84,24 @@ jobs:
       - name: Build gem
         shell: bash
         working-directory: engine
-        if: ${{ matrix.platform == 'x86_64-linux' }}
         run: |
           : Compile gem
           echo "Docker Working Directory: $(pwd)"
           set -x
 
+          # Unfortunately we can't actually parallelize the Ruby versions
+          # because they get bundled into the same gem
           rb-sys-dock \
-            --platform ${{ matrix.platform }} \
+            --platform ${{ matrix._.platform }} \
             --mount-toolchains \
             --directory language_client_ruby \
-            --ruby-versions 3.3,3.2,3.1,3.0,2.7 \
+            --ruby-versions 3.3,3.2,3.1 \
             --build \
-            -- sudo yum install -y perl-IPC-Cmd
-
-      - name: Build gem
+            -- ${{ matrix._.rb-sys-dock-setup }}
+          
+      - name: Show built gem
         shell: bash
-        working-directory: engine
-        if: ${{ matrix.platform != 'x86_64-linux' }}
-        run: |
-          : Compile gem
-          echo "Docker Working Directory: $(pwd)"
-          set -x
-
-          rb-sys-dock \
-            --platform ${{ matrix.platform }} \
-            --mount-toolchains \
-            --directory language_client_ruby \
-            --ruby-versions 3.3,3.2,3.1,3.0,2.7 \
-            --build
+        run: find pkg -name '*.gem'
 
       #################################################################################################################
       #
@@ -147,7 +112,14 @@ jobs:
       #
       #################################################################################################################
 
-      - run: |
-          for i in $(ls pkg/*.gem); do
-            gem push $i
-          done
+      - name: Upload Ruby artifact
+        uses: actions/upload-artifact@v4
+        with:
+          name: gem-${{ matrix._.platform }}
+          path: engine/language_client_ruby/pkg/*.gem
+          if-no-files-found: error
+
+      # - run: |
+      #     for i in $(ls pkg/*.gem); do
+      #       gem push $i
+      #     done
diff --git a/.github/workflows/primary.yml b/.github/workflows/primary.yml
index f7ee7649c..b8761aa0f 100644
--- a/.github/workflows/primary.yml
+++ b/.github/workflows/primary.yml
@@ -46,10 +46,7 @@ jobs:
     runs-on: ubuntu-latest
     steps:
       - uses: actions/checkout@v4
-      - uses: pnpm/action-setup@v3
-        with:
-          version: 9.0.6
-          run_install: false
+      - uses: jdx/mise-action@v2
       - uses: actions/setup-node@v4
         with:
           node-version: 20
@@ -81,6 +78,7 @@ jobs:
     runs-on: ubuntu-latest
     steps:
       - uses: actions/checkout@v4
+      - uses: jdx/mise-action@v2
       - uses: dtolnay/rust-toolchain@stable
         with:
           toolchain: stable
diff --git a/.github/workflows/release.yml b/.github/workflows/release.yml
index 1f7694d24..e25495278 100644
--- a/.github/workflows/release.yml
+++ b/.github/workflows/release.yml
@@ -28,6 +28,7 @@ jobs:
     name: Build WASM
     steps:
       - uses: actions/checkout@v4
+      - uses: jdx/mise-action@v2
       - uses: dtolnay/rust-toolchain@stable
         with:
           toolchain: stable
@@ -38,10 +39,6 @@ jobs:
       - name: Bindgen
         run: cargo install -f wasm-bindgen-cli@0.2.92
         working-directory: engine/baml-schema-wasm
-      - uses: pnpm/action-setup@v3
-        with:
-          version: 8
-          run_install: false
       # Set up Node.js
       - name: Setup Node.js
         uses: actions/setup-node@v4
@@ -97,6 +94,9 @@ jobs:
           path: typescript/vscode-ext/packages/web-panel/dist
           if-no-files-found: error
 
+  build-ruby-release:
+    uses: ./.github/workflows/build-ruby-release.reusable.yaml
+
   build-release:
     strategy:
       fail-fast: false
@@ -105,6 +105,7 @@ jobs:
           - target: aarch64-apple-darwin
             host: macos-14
             node_build: pnpm build --target aarch64-apple-darwin
+            mise: true
 
           # Disabled as python is not supported on aarch64 windows
           # - target: aarch64-pc-windows-msvc
@@ -117,20 +118,27 @@ jobs:
             # need a new version of manylinux to build crates on arm64-linux
             container: ghcr.io/rust-cross/manylinux_2_28-cross:aarch64
             node_build: pnpm build --target aarch64-unknown-linux-gnu --use-napi-cross
+            cargo_args: -p baml-typescript-ffi -p baml-python-ffi
+            baml_build_help: 'off'
 
           - target: x86_64-apple-darwin
             host: macos-latest
             node_build: pnpm build --target x86_64-apple-darwin
+            mise: true
 
           - target: x86_64-pc-windows-msvc
             host: windows-latest
             node_build: pnpm build --target x86_64-pc-windows-msvc
+            setup-python-architecture: x64
+            cargo_args: -p baml-typescript-ffi -p baml-python-ffi
+            baml_build_help: 'off'
 
           - target: x86_64-unknown-linux-gnu
             host: ubuntu-latest
             # Using any of the manylinux containers breaks a bunch of stuff: actions/checkout here, pnpm build there - not worth it.
             container: null
             node_build: pnpm build --target x86_64-unknown-linux-gnu --use-napi-cross
+            mise: true
 
     name: Build ${{ matrix._.target }}
     runs-on: ${{ matrix._.host }}
@@ -141,17 +149,23 @@ jobs:
       - uses: actions/setup-python@v5
         with:
           python-version: "3.8"
-          architecture: ${{ matrix._.host == 'windows-latest' && 'x64' || null }}
+          architecture: ${{ matrix._.setup-python-architecture }}
+
+      - uses: jdx/mise-action@v2
+        if: ${{ matrix._.mise }}
+
       - uses: pnpm/action-setup@v3
         with:
           version: 9.0.6
           run_install: false
+
       - uses: actions/setup-node@v4
         with:
           node-version: 20
           cache: pnpm
           cache-dependency-path: |
             engine/language_client_typescript/pnpm-lock.yaml
+
       # Install rust
       - uses: dtolnay/rust-toolchain@stable
         with:
@@ -171,8 +185,10 @@ jobs:
           cache-on-failure: true
 
       - name: Build Rust
-        run: cargo build --release --target ${{ matrix._.target }}
+        run: cargo build --release --target ${{ matrix._.target }} ${{ matrix._.cargo_args }}
         working-directory: engine
+        env:
+          BAML_BUILD_HELP: ${{ matrix._.baml_build_help }}
 
       # Build Node
       - name: PNPM Build
@@ -202,11 +218,21 @@ jobs:
           name: bindings-${{ matrix._.target }}
           path: engine/language_client_typescript/*.node
           if-no-files-found: error
+  
+  # placeholder fan-in step
+  assert-all-builds-passed:
+    runs-on: ubuntu-latest
+    needs:
+      - build-release
+      - build-ruby-release
+      - build-wasm
+    steps:
+      - run: true
 
   publish-to-pypi:
     environment: release
     if: github.ref_type == 'tag'
-    needs: [build-release, build-wasm]
+    needs: [assert-all-builds-passed] 
     runs-on: ubuntu-latest
     steps:
       - uses: actions/checkout@v4
@@ -227,7 +253,7 @@ jobs:
   publish-to-npm:
     environment: release
     if: github.ref_type == 'tag'
-    needs: [build-release, build-wasm]
+    needs: [assert-all-builds-passed] 
     runs-on: ubuntu-latest
     env:
       NODE_AUTH_TOKEN: ${{ secrets.NPM_TOKEN }}
@@ -274,6 +300,35 @@ jobs:
         env:
           GITHUB_TOKEN: ${{ secrets.GITHUB_TOKEN }}
           NPM_TOKEN: ${{ secrets.NPM_TOKEN }}
+    
+  publish-to-rubygems:
+    environment: release
+    if: github.ref_type == 'tag'
+    needs: [assert-all-builds-passed] 
+    runs-on: ubuntu-latest
+    steps:
+      - uses: actions/checkout@v4
+
+      - uses: rubygems/configure-rubygems-credentials@main
+        with:
+          # https://rubygems.org/profile/oidc/api_key_roles/rg_oidc_akr_p6x4xz53qtk948na3bgy
+          role-to-assume: rg_oidc_akr_p6x4xz53qtk948na3bgy
+
+      - uses: jdx/mise-action@v2
+
+      - uses: actions/download-artifact@v4
+        with:
+          pattern: gem-*
+          path: engine/language_client_ruby/pkg/
+          merge-multiple: true
+
+      - working-directory: engine/language_client_ruby
+        run: |
+          set -euxo pipefail
+          find pkg
+          for i in $(ls pkg/*.gem); do
+            gem push $i
+          done
 
   # publish-vscode:
   #   environment: release
@@ -331,7 +386,11 @@ jobs:
   release-github:
     runs-on: ubuntu-latest
     if: github.ref_type == 'tag'
-    needs: [publish-to-pypi, publish-to-npm]
+    needs: 
+      - publish-to-pypi
+      - publish-to-npm
+      - publish-to-rubygems
+      # - publish-vscode
     steps:
       - uses: actions/checkout@v4
 
diff --git a/.mise.toml b/.mise.toml
index bb001a086..eedb5c2f6 100644
--- a/.mise.toml
+++ b/.mise.toml
@@ -1,2 +1,5 @@
 [tools]
+node = "latest"
 ruby = "3.1"
+pnpm = "latest"
+poetry = "latest"
diff --git a/engine/Cargo.toml b/engine/Cargo.toml
index b79b5b66f..e807ff277 100644
--- a/engine/Cargo.toml
+++ b/engine/Cargo.toml
@@ -6,7 +6,7 @@ members = [
   "baml-fmt",
   "baml-runtime",
   "baml-schema-wasm",
-  "language-client-codegen",
+  "language_client_codegen",
   "language_client_python",
   "language_client_ruby/ext/ruby_ffi",
   "language_client_typescript",
@@ -21,10 +21,9 @@ default-members = [
   # and it's OK to not build this by default because we have to build ts separately (this may
   # also have something to do with resolver=2 and how duplicate dep builds are handled)
   # "baml-schema-wasm",
-  "language-client-codegen",
+  "language_client_codegen",
   "language_client_python",
-  # requires ruby to be installed, does not build for <3.1
-  # "language_client_ruby/ext/ruby_ffi",
+  "language_client_ruby/ext/ruby_ffi",
   "language_client_typescript",
 ]
 
@@ -55,7 +54,7 @@ walkdir = "2.5.0"
 web-time = "1.1.0"
 
 baml-types = { path = "baml-lib/baml-types" }
-internal-baml-codegen = { path = "language-client-codegen" }
+internal-baml-codegen = { path = "language_client_codegen" }
 internal-baml-core = { path = "baml-lib/baml-core" }
 internal-baml-jinja = { path = "baml-lib/jinja" }
 
diff --git a/engine/baml-runtime/Cargo.toml b/engine/baml-runtime/Cargo.toml
index 2ab100ba3..560399e8a 100644
--- a/engine/baml-runtime/Cargo.toml
+++ b/engine/baml-runtime/Cargo.toml
@@ -7,6 +7,9 @@ description.workspace = true
 
 license-file.workspace = true
 
+[build-dependencies]
+anyhow.workspace = true
+
 [dependencies]
 anyhow.workspace = true
 base64.workspace = true
diff --git a/engine/baml-runtime/build.rs b/engine/baml-runtime/build.rs
new file mode 100644
index 000000000..947381dc4
--- /dev/null
+++ b/engine/baml-runtime/build.rs
@@ -0,0 +1,117 @@
+use anyhow::{Context, Result};
+use std::env;
+use std::process::Command;
+
+fn check_ruby_version() -> Result<()> {
+    // Run the 'ruby -v' command to get the Ruby version
+    let output = Command::new("ruby").arg("-v").output().context(format!(
+        "Failed while running 'ruby -v': Ruby does not appear to be installed"
+    ))?;
+
+    // Extract the version number from the string
+    // Typical output: "ruby 3.0.0p0 (2020-12-25 revision 95aff21468) [x86_64-darwin20]"
+    let version_str = String::from_utf8_lossy(&output.stdout);
+    let version = version_str.split_ascii_whitespace().nth(1).ok_or_else(|| {
+        anyhow::anyhow!("Failed to extract Ruby version string from 'ruby -v' output")
+    })?;
+
+    if version.chars().next().map_or(false, |c| c.is_ascii_digit()) && version >= "3.1" {
+        Ok(())
+    } else {
+        Err(anyhow::anyhow!(
+            "BAML must be built with Ruby >= 3.1, but found Ruby {version}"
+        ))
+    }
+}
+
+fn check_clang_support() -> Result<()> {
+    if std::env::var("CARGO_CFG_TARGET_ARCH").ok() != Some("wasm32".to_string()) {
+        return Ok(());
+    }
+
+    // Run the 'clang --version' command to get the Clang version
+    let output = Command::new("clang")
+        .arg("--print-targets")
+        .output()
+        .context(format!("Failed while running 'clang --print-targets'"))?;
+
+    // Extract the version number from the string
+    let target_list = String::from_utf8_lossy(&output.stdout);
+    let target_list = target_list
+        .lines()
+        .filter_map(|line| line.split_once(" - "))
+        .map(|(target, description)| (target.trim(), description.trim()))
+        .map(|(target, _)| target)
+        .collect::<Vec<_>>();
+
+    if !target_list.contains(&"wasm32") {
+        // See https://github.com/briansmith/ring/issues/1824
+        return Err(
+          anyhow::anyhow!("clang does not support the wasm32 target: clang --print-targets returned {:?}", target_list)
+            .context("BAML must be built with Clang with wasm32 target support - you need to 'brew install clang'")
+        );
+    }
+
+    Ok(())
+}
+
+#[allow(dead_code)]
+fn print_env() {
+    let mut env = std::env::vars().collect::<Vec<_>>();
+    env.sort();
+    let env = env;
+
+    println!("Environment variables:");
+    for (key, value) in &env {
+        println!("{}={}", key, value);
+    }
+}
+
+fn main() {
+    let baml_build = env::var("BAML_BUILD_HELP").unwrap_or_else(|_| "AUTO".to_string());
+
+    if baml_build != "AUTO" {
+        return;
+    }
+
+    println!("Running build checks - set BAML_BUILD_HELP=off to disable.");
+
+    let mut errors = vec![];
+
+    if let Err(e) = check_ruby_version().context("Please install mise and direnv to build BAML") {
+        errors.push(e);
+    }
+
+    if let Err(e) = check_clang_support().context("Please install clang and direnv to build BAML") {
+        errors.push(e);
+    }
+
+    if errors.is_empty() {
+        return;
+    }
+
+    println!("");
+    println!("Please install mise and direnv to build BAML (instructions: https://www.notion.so/gloochat/To-build-BAML-0e9e3e9b583e40fb8fb040505b24d65f )");
+    println!("");
+    println!("The following errors occurred during build checks:");
+    for error in errors {
+        println!("{:#}", error);
+    }
+
+    // println!();
+    // print_env();
+    // println!();
+
+    if env::var("RA_RUSTC_WRAPPER").ok() == Some("1".to_string()) {
+        // NB(sam): for some reason, on my machine, rust-analyzer doesn't appear to reflect changes
+        // made in .zshrc/.zprofile/.bashrc/.bash_profile. It's clearly _running_ them, because I see
+        // stuff like STARSHIP_SESSION getting set, but I can't figure out how to point it at my own
+        // Ruby install. Best solution is to just disable it, and let `cargo check` check against
+        // the system Ruby, so the result is that rust-analyzer will soft fail on... I guess Linux?
+        // which is a compromise I can live with for now.
+        println!("Running inside rust-analyzer - will not induce build failure");
+        return;
+    }
+
+    panic!("Build checks failed");
+}
diff --git a/engine/language-client-codegen/Cargo.toml b/engine/language_client_codegen/Cargo.toml
similarity index 100%
rename from engine/language-client-codegen/Cargo.toml
rename to engine/language_client_codegen/Cargo.toml
diff --git a/engine/language-client-codegen/README.md b/engine/language_client_codegen/README.md
similarity index 100%
rename from engine/language-client-codegen/README.md
rename to engine/language_client_codegen/README.md
diff --git a/engine/language-client-codegen/askama.toml b/engine/language_client_codegen/askama.toml
similarity index 100%
rename from engine/language-client-codegen/askama.toml
rename to engine/language_client_codegen/askama.toml
diff --git a/engine/language-client-codegen/src/dir_writer.rs b/engine/language_client_codegen/src/dir_writer.rs
similarity index 100%
rename from engine/language-client-codegen/src/dir_writer.rs
rename to engine/language_client_codegen/src/dir_writer.rs
diff --git a/engine/language-client-codegen/src/lib.rs b/engine/language_client_codegen/src/lib.rs
similarity index 100%
rename from engine/language-client-codegen/src/lib.rs
rename to engine/language_client_codegen/src/lib.rs
diff --git a/engine/language-client-codegen/src/python/generate_types.rs b/engine/language_client_codegen/src/python/generate_types.rs
similarity index 100%
rename from engine/language-client-codegen/src/python/generate_types.rs
rename to engine/language_client_codegen/src/python/generate_types.rs
diff --git a/engine/language-client-codegen/src/python/mod.rs b/engine/language_client_codegen/src/python/mod.rs
similarity index 100%
rename from engine/language-client-codegen/src/python/mod.rs
rename to engine/language_client_codegen/src/python/mod.rs
diff --git a/engine/language-client-codegen/src/python/python_language_features.rs b/engine/language_client_codegen/src/python/python_language_features.rs
similarity index 100%
rename from engine/language-client-codegen/src/python/python_language_features.rs
rename to engine/language_client_codegen/src/python/python_language_features.rs
diff --git a/engine/language-client-codegen/src/python/templates/__init__.py.j2 b/engine/language_client_codegen/src/python/templates/__init__.py.j2
similarity index 100%
rename from engine/language-client-codegen/src/python/templates/__init__.py.j2
rename to engine/language_client_codegen/src/python/templates/__init__.py.j2
diff --git a/engine/language-client-codegen/src/python/templates/async_client.py.j2 b/engine/language_client_codegen/src/python/templates/async_client.py.j2
similarity index 100%
rename from engine/language-client-codegen/src/python/templates/async_client.py.j2
rename to engine/language_client_codegen/src/python/templates/async_client.py.j2
diff --git a/engine/language-client-codegen/src/python/templates/globals.py.j2 b/engine/language_client_codegen/src/python/templates/globals.py.j2
similarity index 100%
rename from engine/language-client-codegen/src/python/templates/globals.py.j2
rename to engine/language_client_codegen/src/python/templates/globals.py.j2
diff --git a/engine/language-client-codegen/src/python/templates/inlinedbaml.py.j2 b/engine/language_client_codegen/src/python/templates/inlinedbaml.py.j2
similarity index 100%
rename from engine/language-client-codegen/src/python/templates/inlinedbaml.py.j2
rename to engine/language_client_codegen/src/python/templates/inlinedbaml.py.j2
diff --git a/engine/language-client-codegen/src/python/templates/partial_types.py.j2 b/engine/language_client_codegen/src/python/templates/partial_types.py.j2
similarity index 100%
rename from engine/language-client-codegen/src/python/templates/partial_types.py.j2
rename to engine/language_client_codegen/src/python/templates/partial_types.py.j2
diff --git a/engine/language-client-codegen/src/python/templates/sync_client.py.j2 b/engine/language_client_codegen/src/python/templates/sync_client.py.j2
similarity index 100%
rename from engine/language-client-codegen/src/python/templates/sync_client.py.j2
rename to engine/language_client_codegen/src/python/templates/sync_client.py.j2
diff --git a/engine/language-client-codegen/src/python/templates/tracing.py.j2 b/engine/language_client_codegen/src/python/templates/tracing.py.j2
similarity index 100%
rename from engine/language-client-codegen/src/python/templates/tracing.py.j2
rename to engine/language_client_codegen/src/python/templates/tracing.py.j2
diff --git a/engine/language-client-codegen/src/python/templates/type_builder.py.j2 b/engine/language_client_codegen/src/python/templates/type_builder.py.j2
similarity index 100%
rename from engine/language-client-codegen/src/python/templates/type_builder.py.j2
rename to engine/language_client_codegen/src/python/templates/type_builder.py.j2
diff --git a/engine/language-client-codegen/src/python/templates/types.py.j2 b/engine/language_client_codegen/src/python/templates/types.py.j2
similarity index 100%
rename from engine/language-client-codegen/src/python/templates/types.py.j2
rename to engine/language_client_codegen/src/python/templates/types.py.j2
diff --git a/engine/language-client-codegen/src/ruby/expression.rs b/engine/language_client_codegen/src/ruby/expression.rs
similarity index 100%
rename from engine/language-client-codegen/src/ruby/expression.rs
rename to engine/language_client_codegen/src/ruby/expression.rs
diff --git a/engine/language-client-codegen/src/ruby/field_type.rs b/engine/language_client_codegen/src/ruby/field_type.rs
similarity index 100%
rename from engine/language-client-codegen/src/ruby/field_type.rs
rename to engine/language_client_codegen/src/ruby/field_type.rs
diff --git a/engine/language-client-codegen/src/ruby/generate_types.rs b/engine/language_client_codegen/src/ruby/generate_types.rs
similarity index 100%
rename from engine/language-client-codegen/src/ruby/generate_types.rs
rename to engine/language_client_codegen/src/ruby/generate_types.rs
diff --git a/engine/language-client-codegen/src/ruby/mod.rs b/engine/language_client_codegen/src/ruby/mod.rs
similarity index 100%
rename from engine/language-client-codegen/src/ruby/mod.rs
rename to engine/language_client_codegen/src/ruby/mod.rs
diff --git a/engine/language-client-codegen/src/ruby/ruby_language_features.rs b/engine/language_client_codegen/src/ruby/ruby_language_features.rs
similarity index 100%
rename from engine/language-client-codegen/src/ruby/ruby_language_features.rs
rename to engine/language_client_codegen/src/ruby/ruby_language_features.rs
diff --git a/engine/language-client-codegen/src/ruby/templates/client.rb.j2 b/engine/language_client_codegen/src/ruby/templates/client.rb.j2
similarity index 100%
rename from engine/language-client-codegen/src/ruby/templates/client.rb.j2
rename to engine/language_client_codegen/src/ruby/templates/client.rb.j2
diff --git a/engine/language-client-codegen/src/ruby/templates/inlined.rb.j2 b/engine/language_client_codegen/src/ruby/templates/inlined.rb.j2
similarity index 100%
rename from engine/language-client-codegen/src/ruby/templates/inlined.rb.j2
rename to engine/language_client_codegen/src/ruby/templates/inlined.rb.j2
diff --git a/engine/language-client-codegen/src/ruby/templates/partial-types.rb.j2 b/engine/language_client_codegen/src/ruby/templates/partial-types.rb.j2
similarity index 100%
rename from engine/language-client-codegen/src/ruby/templates/partial-types.rb.j2
rename to engine/language_client_codegen/src/ruby/templates/partial-types.rb.j2
diff --git a/engine/language-client-codegen/src/ruby/templates/types.rb.j2 b/engine/language_client_codegen/src/ruby/templates/types.rb.j2
similarity index 100%
rename from engine/language-client-codegen/src/ruby/templates/types.rb.j2
rename to engine/language_client_codegen/src/ruby/templates/types.rb.j2
diff --git a/engine/language-client-codegen/src/typescript/generate_types.rs b/engine/language_client_codegen/src/typescript/generate_types.rs
similarity index 100%
rename from engine/language-client-codegen/src/typescript/generate_types.rs
rename to engine/language_client_codegen/src/typescript/generate_types.rs
diff --git a/engine/language-client-codegen/src/typescript/mod.rs b/engine/language_client_codegen/src/typescript/mod.rs
similarity index 100%
rename from engine/language-client-codegen/src/typescript/mod.rs
rename to engine/language_client_codegen/src/typescript/mod.rs
diff --git a/engine/language-client-codegen/src/typescript/templates/async_client.ts.j2 b/engine/language_client_codegen/src/typescript/templates/async_client.ts.j2
similarity index 100%
rename from engine/language-client-codegen/src/typescript/templates/async_client.ts.j2
rename to engine/language_client_codegen/src/typescript/templates/async_client.ts.j2
diff --git a/engine/language-client-codegen/src/typescript/templates/globals.ts.j2 b/engine/language_client_codegen/src/typescript/templates/globals.ts.j2
similarity index 100%
rename from engine/language-client-codegen/src/typescript/templates/globals.ts.j2
rename to engine/language_client_codegen/src/typescript/templates/globals.ts.j2
diff --git a/engine/language-client-codegen/src/typescript/templates/index.ts.j2 b/engine/language_client_codegen/src/typescript/templates/index.ts.j2
similarity index 100%
rename from engine/language-client-codegen/src/typescript/templates/index.ts.j2
rename to engine/language_client_codegen/src/typescript/templates/index.ts.j2
diff --git a/engine/language-client-codegen/src/typescript/templates/inlinedbaml.ts.j2 b/engine/language_client_codegen/src/typescript/templates/inlinedbaml.ts.j2
similarity index 100%
rename from engine/language-client-codegen/src/typescript/templates/inlinedbaml.ts.j2
rename to engine/language_client_codegen/src/typescript/templates/inlinedbaml.ts.j2
diff --git a/engine/language-client-codegen/src/typescript/templates/sync_client.ts.j2 b/engine/language_client_codegen/src/typescript/templates/sync_client.ts.j2
similarity index 100%
rename from engine/language-client-codegen/src/typescript/templates/sync_client.ts.j2
rename to engine/language_client_codegen/src/typescript/templates/sync_client.ts.j2
diff --git a/engine/language-client-codegen/src/typescript/templates/tracing.ts.j2 b/engine/language_client_codegen/src/typescript/templates/tracing.ts.j2
similarity index 100%
rename from engine/language-client-codegen/src/typescript/templates/tracing.ts.j2
rename to engine/language_client_codegen/src/typescript/templates/tracing.ts.j2
diff --git a/engine/language-client-codegen/src/typescript/templates/type_builder.ts.j2 b/engine/language_client_codegen/src/typescript/templates/type_builder.ts.j2
similarity index 100%
rename from engine/language-client-codegen/src/typescript/templates/type_builder.ts.j2
rename to engine/language_client_codegen/src/typescript/templates/type_builder.ts.j2
diff --git a/engine/language-client-codegen/src/typescript/templates/types.ts.j2 b/engine/language_client_codegen/src/typescript/templates/types.ts.j2
similarity index 100%
rename from engine/language-client-codegen/src/typescript/templates/types.ts.j2
rename to engine/language_client_codegen/src/typescript/templates/types.ts.j2
diff --git a/engine/language-client-codegen/src/typescript/typescript_language_features.rs b/engine/language_client_codegen/src/typescript/typescript_language_features.rs
similarity index 100%
rename from engine/language-client-codegen/src/typescript/typescript_language_features.rs
rename to engine/language_client_codegen/src/typescript/typescript_language_features.rs
diff --git a/engine/language-client-codegen/src/version_check.rs b/engine/language_client_codegen/src/version_check.rs
similarity index 100%
rename from engine/language-client-codegen/src/version_check.rs
rename to engine/language_client_codegen/src/version_check.rs
diff --git a/engine/language_client_ruby/Gemfile b/engine/language_client_ruby/Gemfile
index debb9be7b..0c99f8213 100644
--- a/engine/language_client_ruby/Gemfile
+++ b/engine/language_client_ruby/Gemfile
@@ -8,7 +8,7 @@ gemspec
 gem "rake", "~> 13.0"
 gem "rake-compiler", "~> 1.2"
 # Must be kept in sync with Cargo.toml
-gem "rb_sys", "=0.9.97"
+gem "rb_sys", "=0.9.98"
 
 group :test do
   gem "async"
diff --git a/engine/language_client_ruby/Gemfile.lock b/engine/language_client_ruby/Gemfile.lock
index c6e15488f..05071f425 100644
--- a/engine/language_client_ruby/Gemfile.lock
+++ b/engine/language_client_ruby/Gemfile.lock
@@ -1,7 +1,7 @@
 PATH
   remote: .
   specs:
-    baml (0.1.9)
+    baml (0.51.1)
 
 GEM
   remote: https://rubygems.org/
@@ -32,7 +32,7 @@ GEM
     rake (13.1.0)
     rake-compiler (1.2.7)
       rake
-    rb_sys (0.9.97)
+    rb_sys (0.9.98)
     ruby-progressbar (1.13.0)
     safe_type (1.1.1)
     sorbet-coerce (0.7.0)
@@ -53,7 +53,7 @@ DEPENDENCIES
   minitest-reporters
   rake (~> 13.0)
   rake-compiler (~> 1.2)
-  rb_sys (= 0.9.97)
+  rb_sys (= 0.9.98)
   sorbet-coerce
   sorbet-runtime
   sorbet-struct-comparable
diff --git a/engine/language_client_ruby/ext/ruby_ffi/Cargo.toml b/engine/language_client_ruby/ext/ruby_ffi/Cargo.toml
index e295928b7..266de17b2 100644
--- a/engine/language_client_ruby/ext/ruby_ffi/Cargo.toml
+++ b/engine/language_client_ruby/ext/ruby_ffi/Cargo.toml
@@ -10,16 +10,16 @@ crate-type = ["cdylib"]
 
 [dependencies]
 anyhow.workspace = true
-baml-runtime = { path = "../../../baml-runtime", features = [] }
+baml-runtime = { path = "../../../baml-runtime", features = ["internal"] }
 baml-types.workspace = true
 base64.workspace = true
 env_logger.workspace = true
 futures.workspace = true
 indexmap.workspace = true
 log.workspace = true
-magnus = { version = "0.6.4", default = false, features = ["rb-sys"] }
+magnus = { version = "0.6.4", features = ["rb-sys"] }
 # Must be kept in sync with ../../Gemfile
-rb-sys = { version = "0.9.97", features = [
+rb-sys = { version = "0.9.98", features = [
   "global-allocator",
   "bindgen-rbimpls",
   "bindgen-deprecated-types",
@@ -31,5 +31,9 @@ serde_json.workspace = true
 serde_magnus = "0.8.1"
 tokio = { version = "1", features = ["full"] }
 
+[dev-dependencies.magnus]
+version = "0.6.4"
+features = ["rb-sys", "embed"]
+
 [build-dependencies]
 rb-sys-env = { version = "0.1" }
diff --git a/engine/language_client_ruby/ext/ruby_ffi/build.rs b/engine/language_client_ruby/ext/ruby_ffi/build.rs
new file mode 100644
index 000000000..11a8cfa68
--- /dev/null
+++ b/engine/language_client_ruby/ext/ruby_ffi/build.rs
@@ -0,0 +1,24 @@
+use std::process::Command;
+
+pub fn main() {
+    // This is derived from the rustc commands that 'rake compile' runs, e.g.
+    //
+    // cargo rustc --package ruby_ffi --manifest-path /Users/sam/baml/engine/language_client_ruby/ext/ruby_ffi/Cargo.toml --target-dir /Users/sam/baml/engine/target --lib --profile release -- -C linker=clang -L native=/Users/sam/.local/share/mise/installs/ruby/3.1.6/lib -L native=/opt/homebrew/opt/gmp/lib -C link-arg=-Wl,-undefined,dynamic_lookup
+    //
+    // You need to run 'rake compile' from language_client_ruby itself to see these paths.
+
+    match Command::new("mise").args(["where", "ruby"]).output() {
+        Ok(output) => {
+            let ruby_path = String::from_utf8_lossy(&output.stdout).trim().to_string();
+            println!("cargo:rustc-link-search=native={}/lib", ruby_path);
+        }
+        Err(e) => {
+            println!(
+                "cargo:rustc-warning=Failed to execute 'mise where ruby': {}",
+                e
+            );
+        }
+    }
+
+    println!("cargo:rustc-link-arg=-Wl,-undefined,dynamic_lookup");
+}
diff --git a/engine/language_client_ruby/x86-64_linux-setup.sh b/engine/language_client_ruby/x86-64_linux-setup.sh
new file mode 100755
index 000000000..b217077c6
--- /dev/null
+++ b/engine/language_client_ruby/x86-64_linux-setup.sh
@@ -0,0 +1,13 @@
+#!/bin/bash
+
+set -euxo pipefail
+
+# from https://serverfault.com/questions/1161816/mirrorlist-centos-org-no-longer-resolve
+sudo sed -i 's/mirror.centos.org/vault.centos.org/g' /etc/yum.repos.d/*.repo
+sudo sed -i 's/^#.*baseurl=http/baseurl=http/g'      /etc/yum.repos.d/*.repo
+sudo sed -i 's/^mirrorlist=http/#mirrorlist=http/g'  /etc/yum.repos.d/*.repo
+
+ls /etc/yum.repos.d/
+
+ # We need this to build engine/, since it's needed for OpenSSL
+ sudo yum install -y perl-IPC-Cmd