diff --git a/Cargo.lock b/Cargo.lock
index 88a434e..45a55d2 100644
--- a/Cargo.lock
+++ b/Cargo.lock
@@ -179,7 +179,7 @@ checksum = "1462739cb27611015575c0c11df5df7601141071f07518d56fcc1be504cbec97"
 
 [[package]]
 name = "codeowners"
-version = "0.2.7"
+version = "0.2.8"
 dependencies = [
  "assert_cmd",
  "clap",
diff --git a/Cargo.toml b/Cargo.toml
index 7b14a05..2132df5 100644
--- a/Cargo.toml
+++ b/Cargo.toml
@@ -1,6 +1,6 @@
 [package]
 name = "codeowners"
-version = "0.2.7"
+version = "0.2.8"
 edition = "2024"
 
 [profile.release]
diff --git a/rust-toolchain.toml b/rust-toolchain.toml
index a1e0e05..ff1a27d 100644
--- a/rust-toolchain.toml
+++ b/rust-toolchain.toml
@@ -1,4 +1,4 @@
 [toolchain]
-channel = "1.86.0"
+channel = "1.89.0"
 components = ["clippy", "rustfmt"]
 targets = ["x86_64-apple-darwin", "aarch64-apple-darwin", "x86_64-unknown-linux-gnu"]
diff --git a/src/cache/file.rs b/src/cache/file.rs
index 36fc52d..ba76126 100644
--- a/src/cache/file.rs
+++ b/src/cache/file.rs
@@ -21,26 +21,24 @@ const DEFAULT_CACHE_CAPACITY: usize = 10000;
 
 impl Caching for GlobalCache {
     fn get_file_owner(&self, path: &Path) -> Result<Option<FileOwnerCacheEntry>, Error> {
-        if let Some(cache_mutex) = self.file_owner_cache.as_ref() {
-            if let Ok(cache) = cache_mutex.lock() {
-                if let Some(cached_entry) = cache.get(path) {
-                    let timestamp = get_file_timestamp(path)?;
-                    if cached_entry.timestamp == timestamp {
-                        return Ok(Some(cached_entry.clone()));
-                    }
-                }
+        if let Some(cache_mutex) = self.file_owner_cache.as_ref()
+            && let Ok(cache) = cache_mutex.lock()
+            && let Some(cached_entry) = cache.get(path)
+        {
+            let timestamp = get_file_timestamp(path)?;
+            if cached_entry.timestamp == timestamp {
+                return Ok(Some(cached_entry.clone()));
             }
         }
         Ok(None)
     }
 
     fn write_file_owner(&self, path: &Path, owner: Option<String>) {
-        if let Some(cache_mutex) = self.file_owner_cache.as_ref() {
-            if let Ok(mut cache) = cache_mutex.lock() {
-                if let Ok(timestamp) = get_file_timestamp(path) {
-                    cache.insert(path.to_path_buf(), FileOwnerCacheEntry { timestamp, owner });
-                }
-            }
+        if let Some(cache_mutex) = self.file_owner_cache.as_ref()
+            && let Ok(mut cache) = cache_mutex.lock()
+            && let Ok(timestamp) = get_file_timestamp(path)
+        {
+            cache.insert(path.to_path_buf(), FileOwnerCacheEntry { timestamp, owner });
         }
     }
 
diff --git a/src/cli.rs b/src/cli.rs
index f0e45ec..4b6343e 100644
--- a/src/cli.rs
+++ b/src/cli.rs
@@ -16,7 +16,7 @@ enum Command {
             default_value = "false",
             help = "Find the owner from the CODEOWNERS file and just return the team name and yml path"
         )]
-        fast: bool,
+        from_codeowners: bool,
         name: String,
     },
 
@@ -46,6 +46,9 @@ enum Command {
 
     #[clap(about = "Delete the cache file.", visible_alias = "d")]
     DeleteCache,
+
+    #[clap(about = "Compare the CODEOWNERS file to the for-file command.", hide = true)]
+    CrosscheckOwners,
 }
 
 /// A CLI to validate and generate Github's CODEOWNERS file.
@@ -110,9 +113,10 @@ pub fn cli() -> Result<RunResult, RunnerError> {
         Command::Validate => runner::validate(&run_config, vec![]),
         Command::Generate { skip_stage } => runner::generate(&run_config, !skip_stage),
         Command::GenerateAndValidate { skip_stage } => runner::generate_and_validate(&run_config, vec![], !skip_stage),
-        Command::ForFile { name, fast: _ } => runner::for_file(&run_config, &name),
+        Command::ForFile { name, from_codeowners } => runner::for_file(&run_config, &name, from_codeowners),
         Command::ForTeam { name } => runner::for_team(&run_config, &name),
         Command::DeleteCache => runner::delete_cache(&run_config),
+        Command::CrosscheckOwners => runner::crosscheck_owners(&run_config),
     };
 
     Ok(runner_result)
diff --git a/src/crosscheck.rs b/src/crosscheck.rs
new file mode 100644
index 0000000..02eba9b
--- /dev/null
+++ b/src/crosscheck.rs
@@ -0,0 +1,90 @@
+use std::path::Path;
+
+use crate::{
+    cache::Cache,
+    config::Config,
+    ownership::for_file_fast::find_file_owners,
+    project::Project,
+    project_builder::ProjectBuilder,
+    runner::{RunConfig, RunResult, config_from_path, team_for_file_from_codeowners},
+};
+
+pub fn crosscheck_owners(run_config: &RunConfig, cache: &Cache) -> RunResult {
+    match do_crosscheck_owners(run_config, cache) {
+        Ok(mismatches) if mismatches.is_empty() => RunResult {
+            info_messages: vec!["Success! All files match between CODEOWNERS and for-file command.".to_string()],
+            ..Default::default()
+        },
+        Ok(mismatches) => RunResult {
+            validation_errors: mismatches,
+            ..Default::default()
+        },
+        Err(err) => RunResult {
+            io_errors: vec![err],
+            ..Default::default()
+        },
+    }
+}
+
+fn do_crosscheck_owners(run_config: &RunConfig, cache: &Cache) -> Result<Vec<String>, String> {
+    let config = load_config(run_config)?;
+    let project = build_project(&config, run_config, cache)?;
+
+    let mut mismatches: Vec<String> = Vec::new();
+    for file in &project.files {
+        let (codeowners_team, fast_display) = owners_for_file(&file.path, run_config, &config)?;
+        let codeowners_display = codeowners_team.clone().unwrap_or_else(|| "Unowned".to_string());
+        if !is_match(codeowners_team.as_deref(), &fast_display) {
+            mismatches.push(format_mismatch(&project, &file.path, &codeowners_display, &fast_display));
+        }
+    }
+
+    Ok(mismatches)
+}
+
+fn load_config(run_config: &RunConfig) -> Result<Config, String> {
+    config_from_path(&run_config.config_path).map_err(|e| e.to_string())
+}
+
+fn build_project(config: &Config, run_config: &RunConfig, cache: &Cache) -> Result<Project, String> {
+    let mut project_builder = ProjectBuilder::new(
+        config,
+        run_config.project_root.clone(),
+        run_config.codeowners_file_path.clone(),
+        cache,
+    );
+    project_builder.build().map_err(|e| e.to_string())
+}
+
+fn owners_for_file(path: &Path, run_config: &RunConfig, config: &Config) -> Result<(Option<String>, String), String> {
+    let file_path_str = path.to_string_lossy().to_string();
+
+    let codeowners_team = team_for_file_from_codeowners(run_config, &file_path_str)
+        .map_err(|e| e.to_string())?
+        .map(|t| t.name);
+
+    let fast_owners = find_file_owners(&run_config.project_root, config, Path::new(&file_path_str))?;
+    let fast_display = match fast_owners.len() {
+        0 => "Unowned".to_string(),
+        1 => fast_owners[0].team.name.clone(),
+        _ => {
+            let names: Vec<String> = fast_owners.into_iter().map(|fo| fo.team.name).collect();
+            format!("Multiple: {}", names.join(", "))
+        }
+    };
+
+    Ok((codeowners_team, fast_display))
+}
+
+fn is_match(codeowners_team: Option<&str>, fast_display: &str) -> bool {
+    match (codeowners_team, fast_display) {
+        (None, "Unowned") => true,
+        (Some(t), fd) if fd == t => true,
+        _ => false,
+    }
+}
+
+fn format_mismatch(project: &Project, file_path: &Path, codeowners_display: &str, fast_display: &str) -> String {
+    let rel = project.relative_path(file_path).to_string_lossy().to_string();
+    format!("- {}: CODEOWNERS={} fast={}", rel, codeowners_display, fast_display)
+}
diff --git a/src/lib.rs b/src/lib.rs
index e769652..cd7309f 100644
--- a/src/lib.rs
+++ b/src/lib.rs
@@ -1,6 +1,7 @@
 pub mod cache;
 pub(crate) mod common_test;
 pub mod config;
+pub mod crosscheck;
 pub mod ownership;
 pub(crate) mod project;
 pub mod project_builder;
diff --git a/src/ownership/file_generator.rs b/src/ownership/file_generator.rs
index 6d8a34d..8878d41 100644
--- a/src/ownership/file_generator.rs
+++ b/src/ownership/file_generator.rs
@@ -49,15 +49,15 @@ impl FileGenerator {
 }
 
 pub fn compare_lines(a: &String, b: &String) -> Ordering {
-    if let Some((prefix, _)) = a.split_once("**") {
-        if b.starts_with(prefix) {
-            return Ordering::Less;
-        }
+    if let Some((prefix, _)) = a.split_once("**")
+        && b.starts_with(prefix)
+    {
+        return Ordering::Less;
     }
-    if let Some((prefix, _)) = b.split_once("**") {
-        if a.starts_with(prefix) {
-            return Ordering::Greater;
-        }
+    if let Some((prefix, _)) = b.split_once("**")
+        && a.starts_with(prefix)
+    {
+        return Ordering::Greater;
     }
     a.cmp(b)
 }
diff --git a/src/ownership/for_file_fast.rs b/src/ownership/for_file_fast.rs
index 081cb8a..51d9877 100644
--- a/src/ownership/for_file_fast.rs
+++ b/src/ownership/for_file_fast.rs
@@ -32,10 +32,11 @@ pub fn find_file_owners(project_root: &Path, config: &Config, file_path: &Path)
         if let Some(rel_str) = relative_file_path.to_str() {
             let is_config_owned = glob_list_matches(rel_str, &config.owned_globs);
             let is_config_unowned = glob_list_matches(rel_str, &config.unowned_globs);
-            if is_config_owned && !is_config_unowned {
-                if let Some(team) = teams_by_name.get(&team_name) {
-                    sources_by_team.entry(team.name.clone()).or_default().push(Source::TeamFile);
-                }
+            if is_config_owned
+                && !is_config_unowned
+                && let Some(team) = teams_by_name.get(&team_name)
+            {
+                sources_by_team.entry(team.name.clone()).or_default().push(Source::TeamFile);
             }
         }
     }
@@ -194,32 +195,30 @@ fn nearest_package_owner(
         if let Some(rel_str) = parent_rel.to_str() {
             if glob_list_matches(rel_str, &config.ruby_package_paths) {
                 let pkg_yml = current.join("package.yml");
-                if pkg_yml.exists() {
-                    if let Ok(owner) = read_ruby_package_owner(&pkg_yml) {
-                        if let Some(team) = teams_by_name.get(&owner) {
-                            let package_path = parent_rel.join("package.yml");
-                            let package_glob = format!("{rel_str}/**/**");
-                            return Some((
-                                team.name.clone(),
-                                Source::Package(package_path.to_string_lossy().to_string(), package_glob),
-                            ));
-                        }
-                    }
+                if pkg_yml.exists()
+                    && let Ok(owner) = read_ruby_package_owner(&pkg_yml)
+                    && let Some(team) = teams_by_name.get(&owner)
+                {
+                    let package_path = parent_rel.join("package.yml");
+                    let package_glob = format!("{rel_str}/**/**");
+                    return Some((
+                        team.name.clone(),
+                        Source::Package(package_path.to_string_lossy().to_string(), package_glob),
+                    ));
                 }
             }
             if glob_list_matches(rel_str, &config.javascript_package_paths) {
                 let pkg_json = current.join("package.json");
-                if pkg_json.exists() {
-                    if let Ok(owner) = read_js_package_owner(&pkg_json) {
-                        if let Some(team) = teams_by_name.get(&owner) {
-                            let package_path = parent_rel.join("package.json");
-                            let package_glob = format!("{rel_str}/**/**");
-                            return Some((
-                                team.name.clone(),
-                                Source::Package(package_path.to_string_lossy().to_string(), package_glob),
-                            ));
-                        }
-                    }
+                if pkg_json.exists()
+                    && let Ok(owner) = read_js_package_owner(&pkg_json)
+                    && let Some(team) = teams_by_name.get(&owner)
+                {
+                    let package_path = parent_rel.join("package.json");
+                    let package_glob = format!("{rel_str}/**/**");
+                    return Some((
+                        team.name.clone(),
+                        Source::Package(package_path.to_string_lossy().to_string(), package_glob),
+                    ));
                 }
             }
         }
diff --git a/src/ownership/mapper/package_mapper.rs b/src/ownership/mapper/package_mapper.rs
index 5d7dc76..351dfd6 100644
--- a/src/ownership/mapper/package_mapper.rs
+++ b/src/ownership/mapper/package_mapper.rs
@@ -122,10 +122,10 @@ fn remove_nested_packages<'a>(packages: &'a [&'a Package]) -> Vec<&'a Package> {
 
     for package in packages.iter().sorted_by_key(|package| package.package_root()) {
         if let Some(last_package) = top_level_packages.last() {
-            if let (Some(current_root), Some(last_root)) = (package.package_root(), last_package.package_root()) {
-                if !current_root.starts_with(last_root) {
-                    top_level_packages.push(package);
-                }
+            if let (Some(current_root), Some(last_root)) = (package.package_root(), last_package.package_root())
+                && !current_root.starts_with(last_root)
+            {
+                top_level_packages.push(package);
             }
         } else {
             top_level_packages.push(package);
diff --git a/src/ownership/validator.rs b/src/ownership/validator.rs
index 6612e73..dd89f66 100644
--- a/src/ownership/validator.rs
+++ b/src/ownership/validator.rs
@@ -74,13 +74,13 @@ impl Validator {
             .files
             .par_iter()
             .flat_map(|file| {
-                if let Some(owner) = &file.owner {
-                    if !team_names.contains(owner) {
-                        return Some(Error::InvalidTeam {
-                            name: owner.clone(),
-                            path: project.relative_path(&file.path).to_owned(),
-                        });
-                    }
+                if let Some(owner) = &file.owner
+                    && !team_names.contains(owner)
+                {
+                    return Some(Error::InvalidTeam {
+                        name: owner.clone(),
+                        path: project.relative_path(&file.path).to_owned(),
+                    });
                 }
 
                 None
diff --git a/src/project_builder.rs b/src/project_builder.rs
index 3fecf05..9560333 100644
--- a/src/project_builder.rs
+++ b/src/project_builder.rs
@@ -61,14 +61,13 @@ impl<'a> ProjectBuilder<'a> {
         builder.filter_entry(move |entry: &DirEntry| {
             let path = entry.path();
             let file_name = entry.file_name().to_str().unwrap_or("");
-            if let Some(ft) = entry.file_type() {
-                if ft.is_dir() {
-                    if let Ok(rel) = path.strip_prefix(&base_path) {
-                        if rel.components().count() == 1 && ignore_dirs.iter().any(|d| *d == file_name) {
-                            return false;
-                        }
-                    }
-                }
+            if let Some(ft) = entry.file_type()
+                && ft.is_dir()
+                && let Ok(rel) = path.strip_prefix(&base_path)
+                && rel.components().count() == 1
+                && ignore_dirs.iter().any(|d| *d == file_name)
+            {
+                return false;
             }
 
             true
@@ -92,10 +91,10 @@ impl<'a> ProjectBuilder<'a> {
                             let _ = tx.send(entry_type);
                         }
                         Err(report) => {
-                            if let Ok(mut slot) = error_holder.lock() {
-                                if slot.is_none() {
-                                    *slot = Some(report);
-                                }
+                            if let Ok(mut slot) = error_holder.lock()
+                                && slot.is_none()
+                            {
+                                *slot = Some(report);
                             }
                         }
                     }
diff --git a/src/runner.rs b/src/runner.rs
index b1d71d0..345f83f 100644
--- a/src/runner.rs
+++ b/src/runner.rs
@@ -36,10 +36,37 @@ pub struct Runner {
     cache: Cache,
 }
 
-pub fn for_file(run_config: &RunConfig, file_path: &str) -> RunResult {
+pub fn for_file(run_config: &RunConfig, file_path: &str, from_codeowners: bool) -> RunResult {
+    if from_codeowners {
+        return for_file_codeowners_only(run_config, file_path);
+    }
     for_file_optimized(run_config, file_path)
 }
 
+fn for_file_codeowners_only(run_config: &RunConfig, file_path: &str) -> RunResult {
+    match team_for_file_from_codeowners(run_config, file_path) {
+        Ok(Some(team)) => {
+            let relative_team_path = team
+                .path
+                .strip_prefix(&run_config.project_root)
+                .unwrap_or(team.path.as_path())
+                .to_string_lossy()
+                .to_string();
+            RunResult {
+                info_messages: vec![format!(
+                    "Team: {}\nGithub Team: {}\nTeam YML: {}\nDescription:\n- Owner inferred from codeowners file",
+                    team.name, team.github_team, relative_team_path
+                )],
+                ..Default::default()
+            }
+        }
+        Ok(None) => RunResult::default(),
+        Err(err) => RunResult {
+            io_errors: vec![err.to_string()],
+            ..Default::default()
+        },
+    }
+}
 pub fn team_for_file_from_codeowners(run_config: &RunConfig, file_path: &str) -> Result<Option<Team>, Error> {
     let config = config_from_path(&run_config.config_path)?;
     let relative_file_path = Path::new(file_path)
@@ -132,6 +159,10 @@ pub fn delete_cache(run_config: &RunConfig) -> RunResult {
     run_with_runner(run_config, |runner| runner.delete_cache())
 }
 
+pub fn crosscheck_owners(run_config: &RunConfig) -> RunResult {
+    run_with_runner(run_config, |runner| runner.crosscheck_owners())
+}
+
 pub type Runnable = fn(Runner) -> RunResult;
 
 pub fn run_with_runner<F>(run_config: &RunConfig, runnable: F) -> RunResult
@@ -172,7 +203,7 @@ impl fmt::Display for Error {
     }
 }
 
-fn config_from_path(path: &PathBuf) -> Result<Config, Error> {
+pub(crate) fn config_from_path(path: &PathBuf) -> Result<Config, Error> {
     let config_file = File::open(path)
         .change_context(Error::Io(format!("Can't open config file: {}", &path.to_string_lossy())))
         .attach_printable(format!("Can't open config file: {}", &path.to_string_lossy()))?;
@@ -299,6 +330,10 @@ impl Runner {
             },
         }
     }
+
+    pub fn crosscheck_owners(&self) -> RunResult {
+        crate::crosscheck::crosscheck_owners(&self.run_config, &self.cache)
+    }
 }
 
 #[cfg(test)]
diff --git a/tests/fixtures/valid_project_with_overrides/.github/CODEOWNERS b/tests/fixtures/valid_project_with_overrides/.github/CODEOWNERS
new file mode 100644
index 0000000..8ae8814
--- /dev/null
+++ b/tests/fixtures/valid_project_with_overrides/.github/CODEOWNERS
@@ -0,0 +1,53 @@
+# STOP! - DO NOT EDIT THIS FILE MANUALLY
+# This file was automatically generated by "bin/codeownership validate".
+#
+# CODEOWNERS is used for GitHub to suggest code/file owners to various GitHub
+# teams. This is useful when developers create Pull Requests since the
+# code/file owner is notified. Reference GitHub docs for more details:
+# https://help.github.com/en/articles/about-code-owners
+
+
+# Annotations at the top of file
+/frontend/packages/components/datepicker/src/picks/dp.tsx @RockiesTeam
+/frontend/packages/components/list/src/item.tsx @BrewersTeam
+/frontend/packages/components/textfield/src/field.tsx @GiantsTeam
+/frontend/packages/components/textfield/src/fields/small.tsx @GiantsTeam
+/gems/apollo/lib/apollo.rb @GiantsTeam
+/gems/ivy/lib/ivy.rb @CubsTeam
+/gems/lager/lib/lager.rb @BrewersTeam
+/gems/summit/lib/summit.rb @RockiesTeam
+/ruby/app/cubs/services/models/db/price.rb @BrewersTeam
+/ruby/app/cubs/services/play.rb @CubsTeam
+
+# Team-specific owned globs
+/frontend/packages/components/** @BrewersTeam
+/ruby/app/brewers/**/* @BrewersTeam
+/ruby/app/cubs/**/* @CubsTeam
+/ruby/app/giants/**/* @GiantsTeam
+/ruby/app/rockies/**/* @RockiesTeam
+
+# Owner in .codeowner
+/ruby/app/cubs/**/** @CubsTeam
+/ruby/app/cubs/services/models/**/** @RockiesTeam
+
+# Owner metadata key in package.yml
+/packs/games/**/** @RockiesTeam
+/packs/locations/**/** @GiantsTeam
+/packs/schedule/**/** @BrewersTeam
+
+# Owner metadata key in package.json
+/frontend/packages/components/datepicker/**/** @RockiesTeam
+/frontend/packages/components/list/**/** @BrewersTeam
+/frontend/packages/components/textfield/**/** @GiantsTeam
+
+# Team YML ownership
+/config/teams/brewers.yml @BrewersTeam
+/config/teams/cubs.yml @CubsTeam
+/config/teams/giants.yml @GiantsTeam
+/config/teams/rockies.yml @RockiesTeam
+
+# Team owned gems
+/gems/apollo/**/** @GiantsTeam
+/gems/ivy/**/** @CubsTeam
+/gems/lager/**/** @BrewersTeam
+/gems/summit/**/** @RockiesTeam
diff --git a/tests/fixtures/valid_project_with_overrides/config/code_ownership.yml b/tests/fixtures/valid_project_with_overrides/config/code_ownership.yml
new file mode 100644
index 0000000..b0fc127
--- /dev/null
+++ b/tests/fixtures/valid_project_with_overrides/config/code_ownership.yml
@@ -0,0 +1,10 @@
+owned_globs:
+  - "{gems,config,frontend,ruby,components,packs}/**/*.{rb,tsx}"
+ruby_package_paths:
+  - packs/**/*
+javascript_package_paths:
+  - frontend/packages/**
+team_file_glob:
+  - config/teams/**/*.yml
+unbuilt_gems_path: gems
+unowned_globs:
diff --git a/tests/fixtures/valid_project_with_overrides/config/teams/brewers.yml b/tests/fixtures/valid_project_with_overrides/config/teams/brewers.yml
new file mode 100644
index 0000000..72a3654
--- /dev/null
+++ b/tests/fixtures/valid_project_with_overrides/config/teams/brewers.yml
@@ -0,0 +1,11 @@
+name: Brewers
+github:
+  team: '@BrewersTeam'
+owned_globs:
+  - ruby/app/brewers/**/*
+  - frontend/packages/components/**
+subtracted_globs:
+  - frontend/packages/components/textfield/**
+ruby:
+  owned_gems:
+    - lager
\ No newline at end of file
diff --git a/tests/fixtures/valid_project_with_overrides/config/teams/cubs.yml b/tests/fixtures/valid_project_with_overrides/config/teams/cubs.yml
new file mode 100644
index 0000000..81797e5
--- /dev/null
+++ b/tests/fixtures/valid_project_with_overrides/config/teams/cubs.yml
@@ -0,0 +1,9 @@
+name: Cubs
+github:
+  team: '@CubsTeam'
+owned_globs:
+  - ruby/app/cubs/**/*
+ruby:
+  owned_gems:
+    - ivy
+
diff --git a/tests/fixtures/valid_project_with_overrides/config/teams/giants.yml b/tests/fixtures/valid_project_with_overrides/config/teams/giants.yml
new file mode 100644
index 0000000..22a8b9f
--- /dev/null
+++ b/tests/fixtures/valid_project_with_overrides/config/teams/giants.yml
@@ -0,0 +1,8 @@
+name: Giants
+github:
+  team: '@GiantsTeam'
+owned_globs:
+  - ruby/app/giants/**/*
+ruby:
+  owned_gems:
+    - apollo
\ No newline at end of file
diff --git a/tests/fixtures/valid_project_with_overrides/config/teams/rockies.yml b/tests/fixtures/valid_project_with_overrides/config/teams/rockies.yml
new file mode 100644
index 0000000..52cb132
--- /dev/null
+++ b/tests/fixtures/valid_project_with_overrides/config/teams/rockies.yml
@@ -0,0 +1,8 @@
+name: Rockies
+github:
+  team: '@RockiesTeam'
+owned_globs:
+  - ruby/app/rockies/**/*
+ruby:
+  owned_gems:
+    - summit
\ No newline at end of file
diff --git a/tests/fixtures/valid_project_with_overrides/frontend/packages/components/datepicker/package.json b/tests/fixtures/valid_project_with_overrides/frontend/packages/components/datepicker/package.json
new file mode 100644
index 0000000..968cf7a
--- /dev/null
+++ b/tests/fixtures/valid_project_with_overrides/frontend/packages/components/datepicker/package.json
@@ -0,0 +1,5 @@
+{
+    "metadata": {
+        "owner": "Rockies"
+    }
+}
diff --git a/tests/fixtures/valid_project_with_overrides/frontend/packages/components/datepicker/src/picks/dp.tsx b/tests/fixtures/valid_project_with_overrides/frontend/packages/components/datepicker/src/picks/dp.tsx
new file mode 100644
index 0000000..5fad919
--- /dev/null
+++ b/tests/fixtures/valid_project_with_overrides/frontend/packages/components/datepicker/src/picks/dp.tsx
@@ -0,0 +1,3 @@
+// @team Rockies
+export const DP = () => null;
+
diff --git a/tests/fixtures/valid_project_with_overrides/frontend/packages/components/list/package.json b/tests/fixtures/valid_project_with_overrides/frontend/packages/components/list/package.json
new file mode 100644
index 0000000..b9aa9ce
--- /dev/null
+++ b/tests/fixtures/valid_project_with_overrides/frontend/packages/components/list/package.json
@@ -0,0 +1,5 @@
+{
+    "metadata": {
+        "owner": "Brewers"
+    }
+}
diff --git a/tests/fixtures/valid_project_with_overrides/frontend/packages/components/list/src/item.tsx b/tests/fixtures/valid_project_with_overrides/frontend/packages/components/list/src/item.tsx
new file mode 100644
index 0000000..1a2f5cd
--- /dev/null
+++ b/tests/fixtures/valid_project_with_overrides/frontend/packages/components/list/src/item.tsx
@@ -0,0 +1,3 @@
+// @team Brewers
+export const Item = () => null;
+
diff --git a/tests/fixtures/valid_project_with_overrides/frontend/packages/components/textfield/package.json b/tests/fixtures/valid_project_with_overrides/frontend/packages/components/textfield/package.json
new file mode 100644
index 0000000..e10d6bc
--- /dev/null
+++ b/tests/fixtures/valid_project_with_overrides/frontend/packages/components/textfield/package.json
@@ -0,0 +1,5 @@
+{
+    "metadata": {
+        "owner": "Giants"
+    }
+}
diff --git a/tests/fixtures/valid_project_with_overrides/frontend/packages/components/textfield/src/field.tsx b/tests/fixtures/valid_project_with_overrides/frontend/packages/components/textfield/src/field.tsx
new file mode 100644
index 0000000..1ebf50c
--- /dev/null
+++ b/tests/fixtures/valid_project_with_overrides/frontend/packages/components/textfield/src/field.tsx
@@ -0,0 +1,3 @@
+// @team Giants
+export const Field = () => null;
+
diff --git a/tests/fixtures/valid_project_with_overrides/frontend/packages/components/textfield/src/fields/small.tsx b/tests/fixtures/valid_project_with_overrides/frontend/packages/components/textfield/src/fields/small.tsx
new file mode 100644
index 0000000..965ced4
--- /dev/null
+++ b/tests/fixtures/valid_project_with_overrides/frontend/packages/components/textfield/src/fields/small.tsx
@@ -0,0 +1,3 @@
+// @team Giants
+export const Small = () => null;
+
diff --git a/tests/fixtures/valid_project_with_overrides/gems/apollo/lib/apollo.rb b/tests/fixtures/valid_project_with_overrides/gems/apollo/lib/apollo.rb
new file mode 100644
index 0000000..ce16cf8
--- /dev/null
+++ b/tests/fixtures/valid_project_with_overrides/gems/apollo/lib/apollo.rb
@@ -0,0 +1,6 @@
+# @team Giants
+
+module Apollo
+end
+
+
diff --git a/tests/fixtures/valid_project_with_overrides/gems/ivy/lib/ivy.rb b/tests/fixtures/valid_project_with_overrides/gems/ivy/lib/ivy.rb
new file mode 100644
index 0000000..8902daa
--- /dev/null
+++ b/tests/fixtures/valid_project_with_overrides/gems/ivy/lib/ivy.rb
@@ -0,0 +1,6 @@
+# @team Cubs
+
+module Ivy
+end
+
+
diff --git a/tests/fixtures/valid_project_with_overrides/gems/lager/lib/lager.rb b/tests/fixtures/valid_project_with_overrides/gems/lager/lib/lager.rb
new file mode 100644
index 0000000..75cd552
--- /dev/null
+++ b/tests/fixtures/valid_project_with_overrides/gems/lager/lib/lager.rb
@@ -0,0 +1,6 @@
+# @team Brewers
+
+module Lager
+end
+
+
diff --git a/tests/fixtures/valid_project_with_overrides/gems/summit/lib/summit.rb b/tests/fixtures/valid_project_with_overrides/gems/summit/lib/summit.rb
new file mode 100644
index 0000000..cfdbfdd
--- /dev/null
+++ b/tests/fixtures/valid_project_with_overrides/gems/summit/lib/summit.rb
@@ -0,0 +1,6 @@
+# @team Rockies
+
+module Summit
+end
+
+
diff --git a/tests/fixtures/valid_project_with_overrides/packs/games/app/services/stats.rb b/tests/fixtures/valid_project_with_overrides/packs/games/app/services/stats.rb
new file mode 100644
index 0000000..e69de29
diff --git a/tests/fixtures/valid_project_with_overrides/packs/games/package.yml b/tests/fixtures/valid_project_with_overrides/packs/games/package.yml
new file mode 100644
index 0000000..a72f2f3
--- /dev/null
+++ b/tests/fixtures/valid_project_with_overrides/packs/games/package.yml
@@ -0,0 +1 @@
+owner: Rockies
\ No newline at end of file
diff --git a/tests/fixtures/valid_project_with_overrides/packs/locations/app/services/capacity.rb b/tests/fixtures/valid_project_with_overrides/packs/locations/app/services/capacity.rb
new file mode 100644
index 0000000..e69de29
diff --git a/tests/fixtures/valid_project_with_overrides/packs/locations/package.yml b/tests/fixtures/valid_project_with_overrides/packs/locations/package.yml
new file mode 100644
index 0000000..b7d6c55
--- /dev/null
+++ b/tests/fixtures/valid_project_with_overrides/packs/locations/package.yml
@@ -0,0 +1 @@
+owner: Giants
\ No newline at end of file
diff --git a/tests/fixtures/valid_project_with_overrides/packs/schedule/app/services/date.rb b/tests/fixtures/valid_project_with_overrides/packs/schedule/app/services/date.rb
new file mode 100644
index 0000000..e69de29
diff --git a/tests/fixtures/valid_project_with_overrides/packs/schedule/package.yml b/tests/fixtures/valid_project_with_overrides/packs/schedule/package.yml
new file mode 100644
index 0000000..27e4d1a
--- /dev/null
+++ b/tests/fixtures/valid_project_with_overrides/packs/schedule/package.yml
@@ -0,0 +1 @@
+owner: Brewers
\ No newline at end of file
diff --git a/tests/fixtures/valid_project_with_overrides/ruby/app/brewers/lib/util.rb b/tests/fixtures/valid_project_with_overrides/ruby/app/brewers/lib/util.rb
new file mode 100644
index 0000000..3c743d3
--- /dev/null
+++ b/tests/fixtures/valid_project_with_overrides/ruby/app/brewers/lib/util.rb
@@ -0,0 +1,3 @@
+class Util 
+  
+end
\ No newline at end of file
diff --git a/tests/fixtures/valid_project_with_overrides/ruby/app/brewers/services/play.rb b/tests/fixtures/valid_project_with_overrides/ruby/app/brewers/services/play.rb
new file mode 100644
index 0000000..37c3af8
--- /dev/null
+++ b/tests/fixtures/valid_project_with_overrides/ruby/app/brewers/services/play.rb
@@ -0,0 +1,9 @@
+class Play
+  def initialize(team)
+    @team = team
+  end
+
+  def play
+    puts "Playing #{@team}!"
+  end
+end
\ No newline at end of file
diff --git a/tests/fixtures/valid_project_with_overrides/ruby/app/cubs/.codeowner b/tests/fixtures/valid_project_with_overrides/ruby/app/cubs/.codeowner
new file mode 100644
index 0000000..959006a
--- /dev/null
+++ b/tests/fixtures/valid_project_with_overrides/ruby/app/cubs/.codeowner
@@ -0,0 +1,3 @@
+Cubs
+
+
diff --git a/tests/fixtures/valid_project_with_overrides/ruby/app/cubs/services/models/.codeowner b/tests/fixtures/valid_project_with_overrides/ruby/app/cubs/services/models/.codeowner
new file mode 100644
index 0000000..00089bd
--- /dev/null
+++ b/tests/fixtures/valid_project_with_overrides/ruby/app/cubs/services/models/.codeowner
@@ -0,0 +1 @@
+Rockies
\ No newline at end of file
diff --git a/tests/fixtures/valid_project_with_overrides/ruby/app/cubs/services/models/db/price.rb b/tests/fixtures/valid_project_with_overrides/ruby/app/cubs/services/models/db/price.rb
new file mode 100644
index 0000000..5c15cca
--- /dev/null
+++ b/tests/fixtures/valid_project_with_overrides/ruby/app/cubs/services/models/db/price.rb
@@ -0,0 +1,5 @@
+# @team Brewers
+
+class Price
+end
+
diff --git a/tests/fixtures/valid_project_with_overrides/ruby/app/cubs/services/models/entertainment.rb b/tests/fixtures/valid_project_with_overrides/ruby/app/cubs/services/models/entertainment.rb
new file mode 100644
index 0000000..e69de29
diff --git a/tests/fixtures/valid_project_with_overrides/ruby/app/cubs/services/play.rb b/tests/fixtures/valid_project_with_overrides/ruby/app/cubs/services/play.rb
new file mode 100644
index 0000000..c4c169b
--- /dev/null
+++ b/tests/fixtures/valid_project_with_overrides/ruby/app/cubs/services/play.rb
@@ -0,0 +1,5 @@
+# @team Cubs
+
+class Play
+  
+end
\ No newline at end of file
diff --git a/tests/fixtures/valid_project_with_overrides/ruby/app/giants/services/play.rb b/tests/fixtures/valid_project_with_overrides/ruby/app/giants/services/play.rb
new file mode 100644
index 0000000..e69de29
diff --git a/tests/fixtures/valid_project_with_overrides/ruby/app/rockies/services/play.rb b/tests/fixtures/valid_project_with_overrides/ruby/app/rockies/services/play.rb
new file mode 100644
index 0000000..e69de29
diff --git a/tests/valid_project_test.rs b/tests/valid_project_test.rs
index 790f9f2..795bff9 100644
--- a/tests/valid_project_test.rs
+++ b/tests/valid_project_test.rs
@@ -36,6 +36,22 @@ fn test_generate() -> Result<(), Box<dyn Error>> {
     Ok(())
 }
 
+#[test]
+fn test_crosscheck_owners() -> Result<(), Box<dyn Error>> {
+    Command::cargo_bin("codeowners")?
+        .arg("--project-root")
+        .arg("tests/fixtures/valid_project")
+        .arg("--no-cache")
+        .arg("crosscheck-owners")
+        .assert()
+        .success()
+        .stdout(predicate::eq(indoc! {"
+            Success! All files match between CODEOWNERS and for-file command.
+        "}));
+
+    Ok(())
+}
+
 #[test]
 fn test_for_file() -> Result<(), Box<dyn Error>> {
     Command::cargo_bin("codeowners")?
diff --git a/tests/valid_project_with_overrides_test.rs b/tests/valid_project_with_overrides_test.rs
new file mode 100644
index 0000000..6d92fb4
--- /dev/null
+++ b/tests/valid_project_with_overrides_test.rs
@@ -0,0 +1,35 @@
+use assert_cmd::prelude::*;
+use indoc::indoc;
+use predicates::prelude::predicate;
+use std::{error::Error, process::Command};
+
+#[test]
+#[ignore]
+fn test_validate() -> Result<(), Box<dyn Error>> {
+    Command::cargo_bin("codeowners")?
+        .arg("--project-root")
+        .arg("tests/fixtures/valid_project_with_overrides")
+        .arg("--no-cache")
+        .arg("validate")
+        .assert()
+        .success();
+
+    Ok(())
+}
+
+#[test]
+#[ignore]
+fn test_crosscheck_owners() -> Result<(), Box<dyn Error>> {
+    Command::cargo_bin("codeowners")?
+        .arg("--project-root")
+        .arg("tests/fixtures/valid_project_with_overrides")
+        .arg("--no-cache")
+        .arg("crosscheck-owners")
+        .assert()
+        .success()
+        .stdout(predicate::eq(indoc! {"
+            Success! All files match between CODEOWNERS and for-file command.
+        "}));
+
+    Ok(())
+}
diff --git a/tests/verify_compare_for_file_mismatch_test.rs b/tests/verify_compare_for_file_mismatch_test.rs
new file mode 100644
index 0000000..c9252a3
--- /dev/null
+++ b/tests/verify_compare_for_file_mismatch_test.rs
@@ -0,0 +1,70 @@
+use assert_cmd::prelude::*;
+use indoc::indoc;
+use predicates::prelude::*;
+use std::{error::Error, fs, path::Path, process::Command};
+
+mod common;
+use common::setup_fixture_repo;
+
+const FIXTURE: &str = "tests/fixtures/valid_project";
+
+#[test]
+fn test_crosscheck_owners_reports_team_mismatch() -> Result<(), Box<dyn Error>> {
+    // Arrange: copy fixture to temp dir and change a single CODEOWNERS mapping
+    let temp_dir = setup_fixture_repo(Path::new(FIXTURE));
+    let project_root = temp_dir.path();
+    let codeowners_path = project_root.join(".github/CODEOWNERS");
+
+    let original = fs::read_to_string(&codeowners_path)?;
+    // Change payroll.rb ownership from @PayrollTeam to @PaymentsTeam to induce a mismatch
+    let modified = original.replace(
+        "/ruby/app/models/payroll.rb @PayrollTeam",
+        "/ruby/app/models/payroll.rb @PaymentsTeam",
+    );
+    fs::write(&codeowners_path, modified)?;
+
+    // Act + Assert
+    Command::cargo_bin("codeowners")?
+        .arg("--project-root")
+        .arg(project_root)
+        .arg("--no-cache")
+        .arg("crosscheck-owners")
+        .assert()
+        .failure()
+        .stdout(predicate::str::contains(
+            indoc! {"- ruby/app/models/payroll.rb: CODEOWNERS=Payments fast=Payroll"},
+        ));
+
+    Ok(())
+}
+
+#[test]
+fn test_crosscheck_owners_reports_unowned_mismatch() -> Result<(), Box<dyn Error>> {
+    // Arrange: copy fixture to temp dir and remove a CODEOWNERS rule for an owned file
+    let temp_dir = setup_fixture_repo(Path::new(FIXTURE));
+    let project_root = temp_dir.path();
+    let codeowners_path = project_root.join(".github/CODEOWNERS");
+
+    // Remove the explicit mapping for bank_account.rb so CODEOWNERS reports Unowned
+    let original = fs::read_to_string(&codeowners_path)?;
+    let modified: String = original
+        .lines()
+        .filter(|line| !line.trim().starts_with("/ruby/app/models/bank_account.rb "))
+        .map(|l| format!("{}\n", l))
+        .collect();
+    fs::write(&codeowners_path, modified)?;
+
+    // Act + Assert
+    Command::cargo_bin("codeowners")?
+        .arg("--project-root")
+        .arg(project_root)
+        .arg("--no-cache")
+        .arg("crosscheck-owners")
+        .assert()
+        .failure()
+        .stdout(predicate::str::contains(
+            "- ruby/app/models/bank_account.rb: CODEOWNERS=Unowned fast=Payments",
+        ));
+
+    Ok(())
+}