diff --git a/.github/workflows/check.yml b/.github/workflows/check.yml
index 6193b327..113fc112 100644
--- a/.github/workflows/check.yml
+++ b/.github/workflows/check.yml
@@ -41,4 +41,4 @@ jobs:
         run: |
           cd server
           ./bt install --dev
-          ./bt check
+          ./bt test
diff --git a/builder/Cargo.toml b/builder/Cargo.toml
index 48bb795d..645043b9 100644
--- a/builder/Cargo.toml
+++ b/builder/Cargo.toml
@@ -26,3 +26,4 @@ edition = "2021"
 clap = { version = "4.5.19", features = ["derive"] }
 cmd_lib = "1.9.5"
 current_platform = "0.2.0"
+regex = "1.11.1"
diff --git a/builder/src/main.rs b/builder/src/main.rs
index 6831c0b4..f8ca839a 100644
--- a/builder/src/main.rs
+++ b/builder/src/main.rs
@@ -35,6 +35,7 @@ use std::{ffi::OsStr, fs, path::Path, process::Command};
 use clap::{Parser, Subcommand};
 use cmd_lib::run_cmd;
 use current_platform::CURRENT_PLATFORM;
+use regex::Regex;
 
 // ### Local
 //
@@ -60,10 +61,15 @@ enum Commands {
     },
     /// Update all dependencies.
     Update,
-    /// Run lints and compile.
-    Check,
+    /// Run lints and tests.
+    Test,
     /// Build everything.
     Build,
+    /// Change the version for the client, server, and extensions.
+    ChangeVersion {
+        /// The new version number, such as "0.1.1".
+        new_version: String,
+    },
     /// Steps to run before `cargo dist build`.
     Prerelease,
     /// Steps to run after `cargo dist build`. This builds and publishes a
@@ -228,6 +234,29 @@ fn remove_dir_all_if_exists<P: AsRef<Path> + std::fmt::Display>(
     Ok(())
 }
 
+fn search_and_replace_file<
+    P: AsRef<Path> + std::fmt::Display,
+    S1: AsRef<str> + std::fmt::Display,
+    S2: AsRef<str>,
+>(
+    path: P,
+    search_regex: S1,
+    replace_string: S2,
+) -> Result<(), Box<dyn std::error::Error>> {
+    let file_contents = fs::read_to_string(&path)
+        .map_err(|err| -> String { format!("Unable to open file {path} for reading: {err}") })?;
+    let re = Regex::new(search_regex.as_ref())
+        .map_err(|err| -> String { format!("Error in search regex {search_regex}: {err}") })?;
+    let file_contents_replaced = re.replace(&file_contents, replace_string.as_ref());
+    assert_ne!(
+        file_contents, file_contents_replaced,
+        "No replacements made."
+    );
+    fs::write(&path, file_contents_replaced.as_bytes())
+        .map_err(|err| -> String { format!("Error writing to {path}: {err}") })?;
+    Ok(())
+}
+
 // ## Core routines
 //
 // These functions simplify common build-focused development tasks and support
@@ -320,7 +349,7 @@ fn run_update() -> Result<(), Box<dyn std::error::Error>> {
     Ok(())
 }
 
-fn run_check() -> Result<(), Box<dyn std::error::Error>> {
+fn run_test() -> Result<(), Box<dyn std::error::Error>> {
     // On Windows, `cargo sort --check` fails since it default to LF, not CRLF,
     // line endings. Work around this by changing this setting only on Windows.
     // See the
@@ -375,6 +404,27 @@ fn run_build() -> Result<(), Box<dyn std::error::Error>> {
     Ok(())
 }
 
+fn run_change_version(new_version: &String) -> Result<(), Box<dyn std::error::Error>> {
+    let replacement_string = format!("${{1}}{new_version}${{2}}");
+    search_and_replace_file(
+        "Cargo.toml",
+        r#"(\r?\nversion = ")[\d.]+("\r?\n)"#,
+        &replacement_string,
+    )?;
+    let json_search_regex = r#"(\r?\n    "version": ")[\d.]+(",\r?\n)"#;
+    search_and_replace_file(
+        "../client/package.json",
+        json_search_regex,
+        &replacement_string,
+    )?;
+    search_and_replace_file(
+        "../extensions/VSCode/package.json",
+        json_search_regex,
+        &replacement_string,
+    )?;
+    Ok(())
+}
+
 fn run_prerelease() -> Result<(), Box<dyn std::error::Error>> {
     // Clean out all bundled files before the rebuild.
     remove_dir_all_if_exists("../client/static/bundled")?;
@@ -422,8 +472,9 @@ impl Cli {
         match &self.command {
             Commands::Install { dev } => run_install(*dev),
             Commands::Update => run_update(),
-            Commands::Check => run_check(),
+            Commands::Test => run_test(),
             Commands::Build => run_build(),
+            Commands::ChangeVersion { new_version } => run_change_version(new_version),
             Commands::Prerelease => run_prerelease(),
             Commands::Postrelease { target, .. } => run_postrelease(target),
         }