refactor(resolver): move more resolution code into deno_resolver (#26873)

Follow-up to cjs refactor.

This moves most of the resolution code into the deno_resolver crate.
Still pending is the npm resolution code.

6 files changed, 978 insertions, 4 deletions

diff --git a/resolvers/deno/Cargo.toml b/resolvers/deno/Cargo.toml
index 24d50587b..89c0232dc 100644
--- a/resolvers/deno/Cargo.toml
+++ b/resolvers/deno/Cargo.toml
@@ -16,6 +16,8 @@ path = "lib.rs"
 [dependencies]
 anyhow.workspace = true
 base32.workspace = true
+dashmap.workspace = true
+deno_config.workspace = true
 deno_media_type.workspace = true
 deno_package_json.workspace = true
 deno_package_json.features = ["sync"]
diff --git a/resolvers/deno/cjs.rs b/resolvers/deno/cjs.rs
new file mode 100644
index 000000000..dbcbd8b6b
--- /dev/null
+++ b/resolvers/deno/cjs.rs
@@ -0,0 +1,272 @@
+// Copyright 2018-2024 the Deno authors. All rights reserved. MIT license.
+
+use std::sync::Arc;
+
+use dashmap::DashMap;
+use deno_media_type::MediaType;
+use node_resolver::env::NodeResolverEnv;
+use node_resolver::errors::ClosestPkgJsonError;
+use node_resolver::InNpmPackageChecker;
+use node_resolver::NodeModuleKind;
+use node_resolver::PackageJsonResolver;
+use url::Url;
+
+/// Keeps track of what module specifiers were resolved as CJS.
+///
+/// Modules that are `.js`, `.ts`, `.jsx`, and `tsx` are only known to
+/// be CJS or ESM after they're loaded based on their contents. So these
+/// files will be "maybe CJS" until they're loaded.
+#[derive(Debug)]
+pub struct CjsTracker<TEnv: NodeResolverEnv> {
+  is_cjs_resolver: IsCjsResolver<TEnv>,
+  known: DashMap<Url, NodeModuleKind>,
+}
+
+impl<TEnv: NodeResolverEnv> CjsTracker<TEnv> {
+  pub fn new(
+    in_npm_pkg_checker: Arc<dyn InNpmPackageChecker>,
+    pkg_json_resolver: Arc<PackageJsonResolver<TEnv>>,
+    options: IsCjsResolverOptions,
+  ) -> Self {
+    Self {
+      is_cjs_resolver: IsCjsResolver::new(
+        in_npm_pkg_checker,
+        pkg_json_resolver,
+        options,
+      ),
+      known: Default::default(),
+    }
+  }
+
+  /// Checks whether the file might be treated as CJS, but it's not for sure
+  /// yet because the source hasn't been loaded to see whether it contains
+  /// imports or exports.
+  pub fn is_maybe_cjs(
+    &self,
+    specifier: &Url,
+    media_type: MediaType,
+  ) -> Result<bool, ClosestPkgJsonError> {
+    self.treat_as_cjs_with_is_script(specifier, media_type, None)
+  }
+
+  /// Gets whether the file is CJS. If true, this is for sure
+  /// cjs because `is_script` is provided.
+  ///
+  /// `is_script` should be `true` when the contents of the file at the
+  /// provided specifier are known to be a script and not an ES module.
+  pub fn is_cjs_with_known_is_script(
+    &self,
+    specifier: &Url,
+    media_type: MediaType,
+    is_script: bool,
+  ) -> Result<bool, ClosestPkgJsonError> {
+    self.treat_as_cjs_with_is_script(specifier, media_type, Some(is_script))
+  }
+
+  fn treat_as_cjs_with_is_script(
+    &self,
+    specifier: &Url,
+    media_type: MediaType,
+    is_script: Option<bool>,
+  ) -> Result<bool, ClosestPkgJsonError> {
+    let kind = match self
+      .get_known_kind_with_is_script(specifier, media_type, is_script)
+    {
+      Some(kind) => kind,
+      None => self.is_cjs_resolver.check_based_on_pkg_json(specifier)?,
+    };
+    Ok(kind == NodeModuleKind::Cjs)
+  }
+
+  /// Gets the referrer for the specified module specifier.
+  ///
+  /// Generally the referrer should already be tracked by calling
+  /// `is_cjs_with_known_is_script` before calling this method.
+  pub fn get_referrer_kind(&self, specifier: &Url) -> NodeModuleKind {
+    if specifier.scheme() != "file" {
+      return NodeModuleKind::Esm;
+    }
+    self
+      .get_known_kind(specifier, MediaType::from_specifier(specifier))
+      .unwrap_or(NodeModuleKind::Esm)
+  }
+
+  fn get_known_kind(
+    &self,
+    specifier: &Url,
+    media_type: MediaType,
+  ) -> Option<NodeModuleKind> {
+    self.get_known_kind_with_is_script(specifier, media_type, None)
+  }
+
+  fn get_known_kind_with_is_script(
+    &self,
+    specifier: &Url,
+    media_type: MediaType,
+    is_script: Option<bool>,
+  ) -> Option<NodeModuleKind> {
+    self.is_cjs_resolver.get_known_kind_with_is_script(
+      specifier,
+      media_type,
+      is_script,
+      &self.known,
+    )
+  }
+}
+
+#[derive(Debug)]
+pub struct IsCjsResolverOptions {
+  pub detect_cjs: bool,
+  pub is_node_main: bool,
+}
+
+/// Resolves whether a module is CJS or ESM.
+#[derive(Debug)]
+pub struct IsCjsResolver<TEnv: NodeResolverEnv> {
+  in_npm_pkg_checker: Arc<dyn InNpmPackageChecker>,
+  pkg_json_resolver: Arc<PackageJsonResolver<TEnv>>,
+  options: IsCjsResolverOptions,
+}
+
+impl<TEnv: NodeResolverEnv> IsCjsResolver<TEnv> {
+  pub fn new(
+    in_npm_pkg_checker: Arc<dyn InNpmPackageChecker>,
+    pkg_json_resolver: Arc<PackageJsonResolver<TEnv>>,
+    options: IsCjsResolverOptions,
+  ) -> Self {
+    Self {
+      in_npm_pkg_checker,
+      pkg_json_resolver,
+      options,
+    }
+  }
+
+  /// Gets the referrer kind for a script in the LSP.
+  pub fn get_lsp_referrer_kind(
+    &self,
+    specifier: &Url,
+    is_script: Option<bool>,
+  ) -> NodeModuleKind {
+    if specifier.scheme() != "file" {
+      return NodeModuleKind::Esm;
+    }
+    match MediaType::from_specifier(specifier) {
+      MediaType::Mts | MediaType::Mjs | MediaType::Dmts => NodeModuleKind::Esm,
+      MediaType::Cjs | MediaType::Cts | MediaType::Dcts => NodeModuleKind::Cjs,
+      MediaType::Dts => {
+        // dts files are always determined based on the package.json because
+        // they contain imports/exports even when considered CJS
+        self.check_based_on_pkg_json(specifier).unwrap_or(NodeModuleKind::Esm)
+      }
+      MediaType::Wasm |
+      MediaType::Json => NodeModuleKind::Esm,
+      MediaType::JavaScript
+      | MediaType::Jsx
+      | MediaType::TypeScript
+      | MediaType::Tsx
+      // treat these as unknown
+      | MediaType::Css
+      | MediaType::SourceMap
+      | MediaType::Unknown => {
+        match is_script {
+          Some(true) => self.check_based_on_pkg_json(specifier).unwrap_or(NodeModuleKind::Esm),
+          Some(false) | None => NodeModuleKind::Esm,
+        }
+      }
+    }
+  }
+
+  fn get_known_kind_with_is_script(
+    &self,
+    specifier: &Url,
+    media_type: MediaType,
+    is_script: Option<bool>,
+    known_cache: &DashMap<Url, NodeModuleKind>,
+  ) -> Option<NodeModuleKind> {
+    if specifier.scheme() != "file" {
+      return Some(NodeModuleKind::Esm);
+    }
+
+    match media_type {
+      MediaType::Mts | MediaType::Mjs | MediaType::Dmts => Some(NodeModuleKind::Esm),
+      MediaType::Cjs | MediaType::Cts | MediaType::Dcts => Some(NodeModuleKind::Cjs),
+      MediaType::Dts => {
+        // dts files are always determined based on the package.json because
+        // they contain imports/exports even when considered CJS
+        if let Some(value) = known_cache.get(specifier).map(|v| *v) {
+          Some(value)
+        } else {
+          let value = self.check_based_on_pkg_json(specifier).ok();
+          if let Some(value) = value {
+            known_cache.insert(specifier.clone(), value);
+          }
+          Some(value.unwrap_or(NodeModuleKind::Esm))
+        }
+      }
+      MediaType::Wasm |
+      MediaType::Json => Some(NodeModuleKind::Esm),
+      MediaType::JavaScript
+      | MediaType::Jsx
+      | MediaType::TypeScript
+      | MediaType::Tsx
+      // treat these as unknown
+      | MediaType::Css
+      | MediaType::SourceMap
+      | MediaType::Unknown => {
+        if let Some(value) = known_cache.get(specifier).map(|v| *v) {
+          if value == NodeModuleKind::Cjs && is_script == Some(false) {
+            // we now know this is actually esm
+            known_cache.insert(specifier.clone(), NodeModuleKind::Esm);
+            Some(NodeModuleKind::Esm)
+          } else {
+            Some(value)
+          }
+        } else if is_script == Some(false) {
+          // we know this is esm
+            known_cache.insert(specifier.clone(), NodeModuleKind::Esm);
+          Some(NodeModuleKind::Esm)
+        } else {
+          None
+        }
+      }
+    }
+  }
+
+  fn check_based_on_pkg_json(
+    &self,
+    specifier: &Url,
+  ) -> Result<NodeModuleKind, ClosestPkgJsonError> {
+    if self.in_npm_pkg_checker.in_npm_package(specifier) {
+      if let Some(pkg_json) =
+        self.pkg_json_resolver.get_closest_package_json(specifier)?
+      {
+        let is_file_location_cjs = pkg_json.typ != "module";
+        Ok(if is_file_location_cjs {
+          NodeModuleKind::Cjs
+        } else {
+          NodeModuleKind::Esm
+        })
+      } else {
+        Ok(NodeModuleKind::Cjs)
+      }
+    } else if self.options.detect_cjs || self.options.is_node_main {
+      if let Some(pkg_json) =
+        self.pkg_json_resolver.get_closest_package_json(specifier)?
+      {
+        let is_cjs_type = pkg_json.typ == "commonjs"
+          || self.options.is_node_main && pkg_json.typ == "none";
+        Ok(if is_cjs_type {
+          NodeModuleKind::Cjs
+        } else {
+          NodeModuleKind::Esm
+        })
+      } else if self.options.is_node_main {
+        Ok(NodeModuleKind::Cjs)
+      } else {
+        Ok(NodeModuleKind::Esm)
+      }
+    } else {
+      Ok(NodeModuleKind::Esm)
+    }
+  }
+}
diff --git a/resolvers/deno/fs.rs b/resolvers/deno/fs.rs
index 44495fa7c..4929f4508 100644
--- a/resolvers/deno/fs.rs
+++ b/resolvers/deno/fs.rs
@@ -12,6 +12,7 @@ pub struct DirEntry {
 pub trait DenoResolverFs {
   fn read_to_string_lossy(&self, path: &Path) -> std::io::Result<String>;
   fn realpath_sync(&self, path: &Path) -> std::io::Result<PathBuf>;
+  fn exists_sync(&self, path: &Path) -> bool;
   fn is_dir_sync(&self, path: &Path) -> bool;
   fn read_dir_sync(&self, dir_path: &Path) -> std::io::Result<Vec<DirEntry>>;
 }
diff --git a/resolvers/deno/lib.rs b/resolvers/deno/lib.rs
index 57fa67512..a2b6b642f 100644
--- a/resolvers/deno/lib.rs
+++ b/resolvers/deno/lib.rs
@@ -1,5 +1,439 @@
 // Copyright 2018-2024 the Deno authors. All rights reserved. MIT license.
 
+#![deny(clippy::print_stderr)]
+#![deny(clippy::print_stdout)]
+
+use std::path::PathBuf;
+use std::sync::Arc;
+
+use deno_config::workspace::MappedResolution;
+use deno_config::workspace::MappedResolutionDiagnostic;
+use deno_config::workspace::MappedResolutionError;
+use deno_config::workspace::WorkspaceResolvePkgJsonFolderError;
+use deno_config::workspace::WorkspaceResolver;
+use deno_package_json::PackageJsonDepValue;
+use deno_package_json::PackageJsonDepValueParseError;
+use deno_semver::npm::NpmPackageReqReference;
+use fs::DenoResolverFs;
+use node_resolver::env::NodeResolverEnv;
+use node_resolver::errors::NodeResolveError;
+use node_resolver::errors::PackageSubpathResolveError;
+use node_resolver::InNpmPackageChecker;
+use node_resolver::NodeModuleKind;
+use node_resolver::NodeResolution;
+use node_resolver::NodeResolutionMode;
+use node_resolver::NodeResolver;
+use npm::MissingPackageNodeModulesFolderError;
+use npm::NodeModulesOutOfDateError;
+use npm::NpmReqResolver;
+use npm::ResolveIfForNpmPackageError;
+use npm::ResolvePkgFolderFromDenoReqError;
+use npm::ResolveReqWithSubPathError;
+use sloppy_imports::SloppyImportResolverFs;
+use sloppy_imports::SloppyImportsResolutionMode;
+use sloppy_imports::SloppyImportsResolver;
+use thiserror::Error;
+use url::Url;
+
+pub mod cjs;
 pub mod fs;
 pub mod npm;
 pub mod sloppy_imports;
+
+#[derive(Debug, Clone)]
+pub struct DenoResolution {
+  pub url: Url,
+  pub maybe_diagnostic: Option<Box<MappedResolutionDiagnostic>>,
+  pub found_package_json_dep: bool,
+}
+
+#[derive(Debug, Error)]
+pub enum DenoResolveErrorKind {
+  #[error("Importing from the vendor directory is not permitted. Use a remote specifier instead or disable vendoring.")]
+  InvalidVendorFolderImport,
+  #[error(transparent)]
+  MappedResolution(#[from] MappedResolutionError),
+  #[error(transparent)]
+  MissingPackageNodeModulesFolder(#[from] MissingPackageNodeModulesFolderError),
+  #[error(transparent)]
+  Node(#[from] NodeResolveError),
+  #[error(transparent)]
+  NodeModulesOutOfDate(#[from] NodeModulesOutOfDateError),
+  #[error(transparent)]
+  PackageJsonDepValueParse(#[from] PackageJsonDepValueParseError),
+  #[error(transparent)]
+  PackageJsonDepValueUrlParse(url::ParseError),
+  #[error(transparent)]
+  PackageSubpathResolve(#[from] PackageSubpathResolveError),
+  #[error(transparent)]
+  ResolvePkgFolderFromDenoReq(#[from] ResolvePkgFolderFromDenoReqError),
+  #[error(transparent)]
+  WorkspaceResolvePkgJsonFolder(#[from] WorkspaceResolvePkgJsonFolderError),
+}
+
+impl DenoResolveErrorKind {
+  pub fn into_box(self) -> DenoResolveError {
+    DenoResolveError(Box::new(self))
+  }
+}
+
+#[derive(Error, Debug)]
+#[error(transparent)]
+pub struct DenoResolveError(pub Box<DenoResolveErrorKind>);
+
+impl DenoResolveError {
+  pub fn as_kind(&self) -> &DenoResolveErrorKind {
+    &self.0
+  }
+
+  pub fn into_kind(self) -> DenoResolveErrorKind {
+    *self.0
+  }
+}
+
+impl<E> From<E> for DenoResolveError
+where
+  DenoResolveErrorKind: From<E>,
+{
+  fn from(err: E) -> Self {
+    DenoResolveError(Box::new(DenoResolveErrorKind::from(err)))
+  }
+}
+
+#[derive(Debug)]
+pub struct NodeAndNpmReqResolver<
+  Fs: DenoResolverFs,
+  TNodeResolverEnv: NodeResolverEnv,
+> {
+  pub node_resolver: Arc<NodeResolver<TNodeResolverEnv>>,
+  pub npm_req_resolver: Arc<NpmReqResolver<Fs, TNodeResolverEnv>>,
+}
+
+pub struct DenoResolverOptions<
+  'a,
+  Fs: DenoResolverFs,
+  TNodeResolverEnv: NodeResolverEnv,
+  TSloppyImportResolverFs: SloppyImportResolverFs,
+> {
+  pub in_npm_pkg_checker: Arc<dyn InNpmPackageChecker>,
+  pub node_and_req_resolver:
+    Option<NodeAndNpmReqResolver<Fs, TNodeResolverEnv>>,
+  pub sloppy_imports_resolver:
+    Option<Arc<SloppyImportsResolver<TSloppyImportResolverFs>>>,
+  pub workspace_resolver: Arc<WorkspaceResolver>,
+  /// Whether "bring your own node_modules" is enabled where Deno does not
+  /// setup the node_modules directories automatically, but instead uses
+  /// what already exists on the file system.
+  pub is_byonm: bool,
+  pub maybe_vendor_dir: Option<&'a PathBuf>,
+}
+
+/// A resolver that takes care of resolution, taking into account loaded
+/// import map, JSX settings.
+#[derive(Debug)]
+pub struct DenoResolver<
+  Fs: DenoResolverFs,
+  TNodeResolverEnv: NodeResolverEnv,
+  TSloppyImportResolverFs: SloppyImportResolverFs,
+> {
+  in_npm_pkg_checker: Arc<dyn InNpmPackageChecker>,
+  node_and_npm_resolver: Option<NodeAndNpmReqResolver<Fs, TNodeResolverEnv>>,
+  sloppy_imports_resolver:
+    Option<Arc<SloppyImportsResolver<TSloppyImportResolverFs>>>,
+  workspace_resolver: Arc<WorkspaceResolver>,
+  is_byonm: bool,
+  maybe_vendor_specifier: Option<Url>,
+}
+
+impl<
+    Fs: DenoResolverFs,
+    TNodeResolverEnv: NodeResolverEnv,
+    TSloppyImportResolverFs: SloppyImportResolverFs,
+  > DenoResolver<Fs, TNodeResolverEnv, TSloppyImportResolverFs>
+{
+  pub fn new(
+    options: DenoResolverOptions<Fs, TNodeResolverEnv, TSloppyImportResolverFs>,
+  ) -> Self {
+    Self {
+      in_npm_pkg_checker: options.in_npm_pkg_checker,
+      node_and_npm_resolver: options.node_and_req_resolver,
+      sloppy_imports_resolver: options.sloppy_imports_resolver,
+      workspace_resolver: options.workspace_resolver,
+      is_byonm: options.is_byonm,
+      maybe_vendor_specifier: options
+        .maybe_vendor_dir
+        .and_then(|v| deno_path_util::url_from_directory_path(v).ok()),
+    }
+  }
+
+  pub fn resolve(
+    &self,
+    raw_specifier: &str,
+    referrer: &Url,
+    referrer_kind: NodeModuleKind,
+    mode: NodeResolutionMode,
+  ) -> Result<DenoResolution, DenoResolveError> {
+    let mut found_package_json_dep = false;
+    let mut maybe_diagnostic = None;
+    // Use node resolution if we're in an npm package
+    if let Some(node_and_npm_resolver) = self.node_and_npm_resolver.as_ref() {
+      let node_resolver = &node_and_npm_resolver.node_resolver;
+      if referrer.scheme() == "file"
+        && self.in_npm_pkg_checker.in_npm_package(referrer)
+      {
+        return node_resolver
+          .resolve(raw_specifier, referrer, referrer_kind, mode)
+          .map(|res| DenoResolution {
+            url: res.into_url(),
+            found_package_json_dep,
+            maybe_diagnostic,
+          })
+          .map_err(|e| e.into());
+      }
+    }
+
+    // Attempt to resolve with the workspace resolver
+    let result: Result<_, DenoResolveError> = self
+      .workspace_resolver
+      .resolve(raw_specifier, referrer)
+      .map_err(|err| err.into());
+    let result = match result {
+      Ok(resolution) => match resolution {
+        MappedResolution::Normal {
+          specifier,
+          maybe_diagnostic: current_diagnostic,
+        }
+        | MappedResolution::ImportMap {
+          specifier,
+          maybe_diagnostic: current_diagnostic,
+        } => {
+          maybe_diagnostic = current_diagnostic;
+          // do sloppy imports resolution if enabled
+          if let Some(sloppy_imports_resolver) = &self.sloppy_imports_resolver {
+            Ok(
+              sloppy_imports_resolver
+                .resolve(
+                  &specifier,
+                  match mode {
+                    NodeResolutionMode::Execution => {
+                      SloppyImportsResolutionMode::Execution
+                    }
+                    NodeResolutionMode::Types => {
+                      SloppyImportsResolutionMode::Types
+                    }
+                  },
+                )
+                .map(|s| s.into_specifier())
+                .unwrap_or(specifier),
+            )
+          } else {
+            Ok(specifier)
+          }
+        }
+        MappedResolution::WorkspaceJsrPackage { specifier, .. } => {
+          Ok(specifier)
+        }
+        MappedResolution::WorkspaceNpmPackage {
+          target_pkg_json: pkg_json,
+          sub_path,
+          ..
+        } => self
+          .node_and_npm_resolver
+          .as_ref()
+          .unwrap()
+          .node_resolver
+          .resolve_package_subpath_from_deno_module(
+            pkg_json.dir_path(),
+            sub_path.as_deref(),
+            Some(referrer),
+            referrer_kind,
+            mode,
+          )
+          .map_err(|e| e.into()),
+        MappedResolution::PackageJson {
+          dep_result,
+          alias,
+          sub_path,
+          ..
+        } => {
+          // found a specifier in the package.json, so mark that
+          // we need to do an "npm install" later
+          found_package_json_dep = true;
+
+          dep_result
+            .as_ref()
+            .map_err(|e| {
+              DenoResolveErrorKind::PackageJsonDepValueParse(e.clone())
+                .into_box()
+            })
+            .and_then(|dep| match dep {
+              // todo(dsherret): it seems bad that we're converting this
+              // to a url because the req might not be a valid url.
+              PackageJsonDepValue::Req(req) => Url::parse(&format!(
+                "npm:{}{}",
+                req,
+                sub_path.map(|s| format!("/{}", s)).unwrap_or_default()
+              ))
+              .map_err(|e| {
+                DenoResolveErrorKind::PackageJsonDepValueUrlParse(e).into_box()
+              }),
+              PackageJsonDepValue::Workspace(version_req) => self
+                .workspace_resolver
+                .resolve_workspace_pkg_json_folder_for_pkg_json_dep(
+                  alias,
+                  version_req,
+                )
+                .map_err(|e| {
+                  DenoResolveErrorKind::WorkspaceResolvePkgJsonFolder(e)
+                    .into_box()
+                })
+                .and_then(|pkg_folder| {
+                  self
+                    .node_and_npm_resolver
+                    .as_ref()
+                    .unwrap()
+                    .node_resolver
+                    .resolve_package_subpath_from_deno_module(
+                      pkg_folder,
+                      sub_path.as_deref(),
+                      Some(referrer),
+                      referrer_kind,
+                      mode,
+                    )
+                    .map_err(|e| {
+                      DenoResolveErrorKind::PackageSubpathResolve(e).into_box()
+                    })
+                }),
+            })
+        }
+      },
+      Err(err) => Err(err),
+    };
+
+    // When the user is vendoring, don't allow them to import directly from the vendor/ directory
+    // as it might cause them confusion or duplicate dependencies. Additionally, this folder has
+    // special treatment in the language server so it will definitely cause issues/confusion there
+    // if they do this.
+    if let Some(vendor_specifier) = &self.maybe_vendor_specifier {
+      if let Ok(specifier) = &result {
+        if specifier.as_str().starts_with(vendor_specifier.as_str()) {
+          return Err(
+            DenoResolveErrorKind::InvalidVendorFolderImport.into_box(),
+          );
+        }
+      }
+    }
+
+    let Some(NodeAndNpmReqResolver {
+      node_resolver,
+      npm_req_resolver,
+    }) = &self.node_and_npm_resolver
+    else {
+      return Ok(DenoResolution {
+        url: result?,
+        maybe_diagnostic,
+        found_package_json_dep,
+      });
+    };
+
+    match result {
+      Ok(specifier) => {
+        if let Ok(npm_req_ref) =
+          NpmPackageReqReference::from_specifier(&specifier)
+        {
+          // check if the npm specifier resolves to a workspace member
+          if let Some(pkg_folder) = self
+            .workspace_resolver
+            .resolve_workspace_pkg_json_folder_for_npm_specifier(
+              npm_req_ref.req(),
+            )
+          {
+            return node_resolver
+              .resolve_package_subpath_from_deno_module(
+                pkg_folder,
+                npm_req_ref.sub_path(),
+                Some(referrer),
+                referrer_kind,
+                mode,
+              )
+              .map(|url| DenoResolution {
+                url,
+                maybe_diagnostic,
+                found_package_json_dep,
+              })
+              .map_err(|e| e.into());
+          }
+
+          // do npm resolution for byonm
+          if self.is_byonm {
+            return npm_req_resolver
+              .resolve_req_reference(
+                &npm_req_ref,
+                referrer,
+                referrer_kind,
+                mode,
+              )
+              .map(|url| DenoResolution {
+                url,
+                maybe_diagnostic,
+                found_package_json_dep,
+              })
+              .map_err(|err| match err {
+                ResolveReqWithSubPathError::MissingPackageNodeModulesFolder(
+                  err,
+                ) => err.into(),
+                ResolveReqWithSubPathError::ResolvePkgFolderFromDenoReq(
+                  err,
+                ) => err.into(),
+                ResolveReqWithSubPathError::PackageSubpathResolve(err) => {
+                  err.into()
+                }
+              });
+          }
+        }
+
+        Ok(DenoResolution {
+          url: node_resolver
+            .handle_if_in_node_modules(&specifier)
+            .unwrap_or(specifier),
+          maybe_diagnostic,
+          found_package_json_dep,
+        })
+      }
+      Err(err) => {
+        // If byonm, check if the bare specifier resolves to an npm package
+        if self.is_byonm && referrer.scheme() == "file" {
+          let maybe_resolution = npm_req_resolver
+            .resolve_if_for_npm_pkg(
+              raw_specifier,
+              referrer,
+              referrer_kind,
+              mode,
+            )
+            .map_err(|e| match e {
+              ResolveIfForNpmPackageError::NodeResolve(e) => {
+                DenoResolveErrorKind::Node(e).into_box()
+              }
+              ResolveIfForNpmPackageError::NodeModulesOutOfDate(e) => e.into(),
+            })?;
+          if let Some(res) = maybe_resolution {
+            match res {
+              NodeResolution::Module(url) => {
+                return Ok(DenoResolution {
+                  url,
+                  maybe_diagnostic,
+                  found_package_json_dep,
+                })
+              }
+              NodeResolution::BuiltIn(_) => {
+                // don't resolve bare specifiers for built-in modules via node resolution
+              }
+            }
+          }
+        }
+
+        Err(err)
+      }
+    }
+  }
+}
diff --git a/resolvers/deno/npm/byonm.rs b/resolvers/deno/npm/byonm.rs
index b85117052..e9182d47a 100644
--- a/resolvers/deno/npm/byonm.rs
+++ b/resolvers/deno/npm/byonm.rs
@@ -16,7 +16,7 @@ use node_resolver::errors::PackageFolderResolveIoError;
 use node_resolver::errors::PackageJsonLoadError;
 use node_resolver::errors::PackageNotFoundError;
 use node_resolver::InNpmPackageChecker;
-use node_resolver::NpmResolver;
+use node_resolver::NpmPackageFolderResolver;
 use node_resolver::PackageJsonResolverRc;
 use thiserror::Error;
 use url::Url;
@@ -24,6 +24,8 @@ use url::Url;
 use crate::fs::DenoResolverFs;
 
 use super::local::normalize_pkg_name_for_node_modules_deno_folder;
+use super::CliNpmReqResolver;
+use super::ResolvePkgFolderFromDenoReqError;
 
 #[derive(Debug, Error)]
 pub enum ByonmResolvePkgFolderFromDenoReqError {
@@ -303,7 +305,24 @@ impl<Fs: DenoResolverFs, TEnv: NodeResolverEnv> ByonmNpmResolver<Fs, TEnv> {
 impl<
     Fs: DenoResolverFs + Send + Sync + std::fmt::Debug,
     TEnv: NodeResolverEnv,
-  > NpmResolver for ByonmNpmResolver<Fs, TEnv>
+  > CliNpmReqResolver for ByonmNpmResolver<Fs, TEnv>
+{
+  fn resolve_pkg_folder_from_deno_module_req(
+    &self,
+    req: &PackageReq,
+    referrer: &Url,
+  ) -> Result<PathBuf, ResolvePkgFolderFromDenoReqError> {
+    ByonmNpmResolver::resolve_pkg_folder_from_deno_module_req(
+      self, req, referrer,
+    )
+    .map_err(ResolvePkgFolderFromDenoReqError::Byonm)
+  }
+}
+
+impl<
+    Fs: DenoResolverFs + Send + Sync + std::fmt::Debug,
+    TEnv: NodeResolverEnv,
+  > NpmPackageFolderResolver for ByonmNpmResolver<Fs, TEnv>
 {
   fn resolve_package_folder_from_package(
     &self,
diff --git a/resolvers/deno/npm/mod.rs b/resolvers/deno/npm/mod.rs
index 45e2341c7..b0aec71b0 100644
--- a/resolvers/deno/npm/mod.rs
+++ b/resolvers/deno/npm/mod.rs
@@ -1,10 +1,256 @@
 // Copyright 2018-2024 the Deno authors. All rights reserved. MIT license.
 
-mod byonm;
-mod local;
+use std::fmt::Debug;
+use std::path::PathBuf;
+use std::sync::Arc;
+
+use deno_semver::npm::NpmPackageReqReference;
+use deno_semver::package::PackageReq;
+use node_resolver::env::NodeResolverEnv;
+use node_resolver::errors::NodeResolveError;
+use node_resolver::errors::NodeResolveErrorKind;
+use node_resolver::errors::PackageFolderResolveErrorKind;
+use node_resolver::errors::PackageFolderResolveIoError;
+use node_resolver::errors::PackageNotFoundError;
+use node_resolver::errors::PackageResolveErrorKind;
+use node_resolver::errors::PackageSubpathResolveError;
+use node_resolver::InNpmPackageChecker;
+use node_resolver::NodeModuleKind;
+use node_resolver::NodeResolution;
+use node_resolver::NodeResolutionMode;
+use node_resolver::NodeResolver;
+use thiserror::Error;
+use url::Url;
+
+use crate::fs::DenoResolverFs;
 
 pub use byonm::ByonmInNpmPackageChecker;
 pub use byonm::ByonmNpmResolver;
 pub use byonm::ByonmNpmResolverCreateOptions;
 pub use byonm::ByonmResolvePkgFolderFromDenoReqError;
 pub use local::normalize_pkg_name_for_node_modules_deno_folder;
+
+mod byonm;
+mod local;
+
+#[derive(Debug, Error)]
+#[error("Could not resolve \"{}\", but found it in a package.json. Deno expects the node_modules/ directory to be up to date. Did you forget to run `deno install`?", specifier)]
+pub struct NodeModulesOutOfDateError {
+  pub specifier: String,
+}
+
+#[derive(Debug, Error)]
+#[error("Could not find '{}'. Deno expects the node_modules/ directory to be up to date. Did you forget to run `deno install`?", package_json_path.display())]
+pub struct MissingPackageNodeModulesFolderError {
+  pub package_json_path: PathBuf,
+}
+
+#[derive(Debug, Error)]
+pub enum ResolveIfForNpmPackageError {
+  #[error(transparent)]
+  NodeResolve(#[from] NodeResolveError),
+  #[error(transparent)]
+  NodeModulesOutOfDate(#[from] NodeModulesOutOfDateError),
+}
+
+#[derive(Debug, Error)]
+pub enum ResolveReqWithSubPathError {
+  #[error(transparent)]
+  MissingPackageNodeModulesFolder(#[from] MissingPackageNodeModulesFolderError),
+  #[error(transparent)]
+  ResolvePkgFolderFromDenoReq(#[from] ResolvePkgFolderFromDenoReqError),
+  #[error(transparent)]
+  PackageSubpathResolve(#[from] PackageSubpathResolveError),
+}
+
+#[derive(Debug, Error)]
+pub enum ResolvePkgFolderFromDenoReqError {
+  // todo(dsherret): don't use anyhow here
+  #[error(transparent)]
+  Managed(anyhow::Error),
+  #[error(transparent)]
+  Byonm(#[from] ByonmResolvePkgFolderFromDenoReqError),
+}
+
+// todo(dsherret): a temporary trait until we extract
+// out the CLI npm resolver into here
+pub trait CliNpmReqResolver: Debug + Send + Sync {
+  fn resolve_pkg_folder_from_deno_module_req(
+    &self,
+    req: &PackageReq,
+    referrer: &Url,
+  ) -> Result<PathBuf, ResolvePkgFolderFromDenoReqError>;
+}
+
+pub struct NpmReqResolverOptions<
+  Fs: DenoResolverFs,
+  TNodeResolverEnv: NodeResolverEnv,
+> {
+  /// The resolver when "bring your own node_modules" is enabled where Deno
+  /// does not setup the node_modules directories automatically, but instead
+  /// uses what already exists on the file system.
+  pub byonm_resolver: Option<Arc<ByonmNpmResolver<Fs, TNodeResolverEnv>>>,
+  pub fs: Fs,
+  pub in_npm_pkg_checker: Arc<dyn InNpmPackageChecker>,
+  pub node_resolver: Arc<NodeResolver<TNodeResolverEnv>>,
+  pub npm_req_resolver: Arc<dyn CliNpmReqResolver>,
+}
+
+#[derive(Debug)]
+pub struct NpmReqResolver<Fs: DenoResolverFs, TNodeResolverEnv: NodeResolverEnv>
+{
+  byonm_resolver: Option<Arc<ByonmNpmResolver<Fs, TNodeResolverEnv>>>,
+  fs: Fs,
+  in_npm_pkg_checker: Arc<dyn InNpmPackageChecker>,
+  node_resolver: Arc<NodeResolver<TNodeResolverEnv>>,
+  npm_resolver: Arc<dyn CliNpmReqResolver>,
+}
+
+impl<Fs: DenoResolverFs, TNodeResolverEnv: NodeResolverEnv>
+  NpmReqResolver<Fs, TNodeResolverEnv>
+{
+  pub fn new(options: NpmReqResolverOptions<Fs, TNodeResolverEnv>) -> Self {
+    Self {
+      byonm_resolver: options.byonm_resolver,
+      fs: options.fs,
+      in_npm_pkg_checker: options.in_npm_pkg_checker,
+      node_resolver: options.node_resolver,
+      npm_resolver: options.npm_req_resolver,
+    }
+  }
+
+  pub fn resolve_req_reference(
+    &self,
+    req_ref: &NpmPackageReqReference,
+    referrer: &Url,
+    referrer_kind: NodeModuleKind,
+    mode: NodeResolutionMode,
+  ) -> Result<Url, ResolveReqWithSubPathError> {
+    self.resolve_req_with_sub_path(
+      req_ref.req(),
+      req_ref.sub_path(),
+      referrer,
+      referrer_kind,
+      mode,
+    )
+  }
+
+  pub fn resolve_req_with_sub_path(
+    &self,
+    req: &PackageReq,
+    sub_path: Option<&str>,
+    referrer: &Url,
+    referrer_kind: NodeModuleKind,
+    mode: NodeResolutionMode,
+  ) -> Result<Url, ResolveReqWithSubPathError> {
+    let package_folder = self
+      .npm_resolver
+      .resolve_pkg_folder_from_deno_module_req(req, referrer)?;
+    let resolution_result =
+      self.node_resolver.resolve_package_subpath_from_deno_module(
+        &package_folder,
+        sub_path,
+        Some(referrer),
+        referrer_kind,
+        mode,
+      );
+    match resolution_result {
+      Ok(url) => Ok(url),
+      Err(err) => {
+        if self.byonm_resolver.is_some() {
+          let package_json_path = package_folder.join("package.json");
+          if !self.fs.exists_sync(&package_json_path) {
+            return Err(
+              MissingPackageNodeModulesFolderError { package_json_path }.into(),
+            );
+          }
+        }
+        Err(err.into())
+      }
+    }
+  }
+
+  pub fn resolve_if_for_npm_pkg(
+    &self,
+    specifier: &str,
+    referrer: &Url,
+    referrer_kind: NodeModuleKind,
+    mode: NodeResolutionMode,
+  ) -> Result<Option<NodeResolution>, ResolveIfForNpmPackageError> {
+    let resolution_result =
+      self
+        .node_resolver
+        .resolve(specifier, referrer, referrer_kind, mode);
+    match resolution_result {
+      Ok(res) => Ok(Some(res)),
+      Err(err) => {
+        let err = err.into_kind();
+        match err {
+          NodeResolveErrorKind::RelativeJoin(_)
+          | NodeResolveErrorKind::PackageImportsResolve(_)
+          | NodeResolveErrorKind::UnsupportedEsmUrlScheme(_)
+          | NodeResolveErrorKind::DataUrlReferrer(_)
+          | NodeResolveErrorKind::TypesNotFound(_)
+          | NodeResolveErrorKind::FinalizeResolution(_) => {
+            Err(ResolveIfForNpmPackageError::NodeResolve(err.into()))
+          }
+          NodeResolveErrorKind::PackageResolve(err) => {
+            let err = err.into_kind();
+            match err {
+              PackageResolveErrorKind::ClosestPkgJson(_)
+              | PackageResolveErrorKind::InvalidModuleSpecifier(_)
+              | PackageResolveErrorKind::ExportsResolve(_)
+              | PackageResolveErrorKind::SubpathResolve(_) => {
+                Err(ResolveIfForNpmPackageError::NodeResolve(
+                  NodeResolveErrorKind::PackageResolve(err.into()).into(),
+                ))
+              }
+              PackageResolveErrorKind::PackageFolderResolve(err) => {
+                match err.as_kind() {
+                  PackageFolderResolveErrorKind::Io(
+                    PackageFolderResolveIoError { package_name, .. },
+                  )
+                  | PackageFolderResolveErrorKind::PackageNotFound(
+                    PackageNotFoundError { package_name, .. },
+                  ) => {
+                    if self.in_npm_pkg_checker.in_npm_package(referrer) {
+                      return Err(ResolveIfForNpmPackageError::NodeResolve(
+                        NodeResolveErrorKind::PackageResolve(err.into()).into(),
+                      ));
+                    }
+                    if let Some(byonm_npm_resolver) = &self.byonm_resolver {
+                      if byonm_npm_resolver
+                        .find_ancestor_package_json_with_dep(
+                          package_name,
+                          referrer,
+                        )
+                        .is_some()
+                      {
+                        return Err(
+                          ResolveIfForNpmPackageError::NodeModulesOutOfDate(
+                            NodeModulesOutOfDateError {
+                              specifier: specifier.to_string(),
+                            },
+                          ),
+                        );
+                      }
+                    }
+                    Ok(None)
+                  }
+                  PackageFolderResolveErrorKind::ReferrerNotFound(_) => {
+                    if self.in_npm_pkg_checker.in_npm_package(referrer) {
+                      return Err(ResolveIfForNpmPackageError::NodeResolve(
+                        NodeResolveErrorKind::PackageResolve(err.into()).into(),
+                      ));
+                    }
+                    Ok(None)
+                  }
+                }
+              }
+            }
+          }
+        }
+      }
+    }
+  }
+}