fix: normalize Windows file URIs for DAP source paths

crates/engine/src/exec/dap.rs

@@ -37,6 +37,7 @@ use crate::{
         inline_frames_for_operation, resolve_typed_variable_values, resolve_variable_values,
     },
     exec::state::CurrentCycleInfo,
+    normalize_source_path,
 };
 
 // DAP CONFIG
@@ -650,35 +651,6 @@ fn is_internal_procedure(context_name: &str) -> bool {
     context_name.contains("::intrinsics::")
 }
 
-fn normalize_source_path(path: &str) -> String {
-    let path = path.trim();
-    let path = path.strip_prefix("file://").unwrap_or(path);
-    let path = path.replace('\\', "/");
-
-    let is_absolute = path.starts_with('/');
-    let mut parts = Vec::new();
-    for part in path.split('/') {
-        match part {
-            "" | "." => {}
-            ".." => {
-                if parts.last().is_some_and(|last| *last != "..") {
-                    parts.pop();
-                } else {
-                    parts.push(part);
-                }
-            }
-            _ => parts.push(part),
-        }
-    }
-
-    let normalized = parts.join("/");
-    if is_absolute && !normalized.is_empty() {
-        format!("/{normalized}")
-    } else {
-        normalized
-    }
-}
-
 fn strip_source_prefix(path: &str, prefix: &str) -> Option<String> {
     let path = path.trim_start_matches('/');
     let prefix = prefix.trim_start_matches('/').trim_end_matches('/');
@@ -2831,6 +2803,26 @@ mod tests {
             "/workspace/compiler/examples/fibonacci/src/lib.rs",
             &[],
         ));
+        assert!(source_paths_match(
+            "file:///C:/workspace/compiler/examples/fibonacci/src/lib.rs",
+            "C:/workspace/compiler/examples/fibonacci/src/lib.rs",
+            &[],
+        ));
+        assert!(source_paths_match(
+            "file:///C:/workspace/compiler/examples/fibonacci/src/lib.rs",
+            "c:/workspace/compiler/examples/fibonacci/src/lib.rs",
+            &[],
+        ));
+        assert!(source_paths_match(
+            "file://localhost/C:/workspace/compiler/examples/fibonacci/src/lib.rs",
+            "c:/workspace/compiler/examples/fibonacci/src/lib.rs",
+            &[],
+        ));
+        assert!(source_paths_match(
+            "file:///C:/workspace/compiler/examples/fibonacci/src/lib.rs",
+            "src/lib.rs",
+            &["c:/workspace/compiler/examples/fibonacci".into()],
+        ));
         assert!(!source_paths_match(
             "/workspace/compiler/examples/fibonacci/src/lib.rs",
             "src/lib.rs",

crates/engine/src/lib.rs

@@ -4,6 +4,7 @@ pub mod felt;
 mod linker;
 pub mod profiling;
 mod registry;
+mod source_path;
 #[cfg(test)]
 mod test_utils;
 
@@ -17,4 +18,5 @@ pub use self::{
     felt::{Felt, FromMidenRepr, ToMidenRepr, bytes_to_words, push_wasm_ty_to_operand_stack},
     linker::LinkLibrary,
     registry::HybridPackageRegistry,
+    source_path::normalize_source_path,
 };

crates/engine/src/source_path.rs

@@ -0,0 +1,78 @@
+use miden_debug_types::Uri;
+
+/// Converts a source URI or path into a stable form for loading and comparison.
+pub fn normalize_source_path(path: &str) -> String {
+    let path = path.trim();
+    let path = Uri::new(path)
+        .to_path()
+        .map(|path| path.to_string_lossy().into_owned())
+        .unwrap_or_else(|| path.to_owned());
+    let mut path = path.replace('\\', "/");
+    if path
+        .as_bytes()
+        .get(0..2)
+        .is_some_and(|bytes| bytes[0].is_ascii_alphabetic() && bytes[1] == b':')
+    {
+        path.replace_range(..1, &path[..1].to_ascii_lowercase());
+    }
+
+    let is_absolute = path.starts_with('/');
+    let mut parts = Vec::new();
+    for part in path.split('/') {
+        match part {
+            "" | "." => {}
+            ".." => {
+                if parts.last().is_some_and(|last| *last != "..") {
+                    parts.pop();
+                } else {
+                    parts.push(part);
+                }
+            }
+            _ => parts.push(part),
+        }
+    }
+
+    let normalized = parts.join("/");
+    if is_absolute && !normalized.is_empty() {
+        format!("/{normalized}")
+    } else {
+        normalized
+    }
+}
+
+#[cfg(test)]
+mod tests {
+    use super::normalize_source_path;
+
+    #[test]
+    fn normalizes_file_uris_and_windows_drive_letters() {
+        assert_eq!(
+            normalize_source_path("file:///C:/Users/me/program.masm"),
+            "c:/Users/me/program.masm"
+        );
+        assert_eq!(
+            normalize_source_path("file:///c:/Users/me/program.masm"),
+            "c:/Users/me/program.masm"
+        );
+        assert_eq!(
+            normalize_source_path("file://localhost/C:/Users/me/program.masm"),
+            "c:/Users/me/program.masm"
+        );
+        assert_eq!(
+            normalize_source_path("C:\\Users\\me\\program.masm"),
+            "c:/Users/me/program.masm"
+        );
+    }
+
+    #[test]
+    fn normalizes_path_components() {
+        assert_eq!(
+            normalize_source_path("/home/me/./src/../program.masm"),
+            "/home/me/program.masm"
+        );
+        assert_eq!(
+            normalize_source_path("relative/./src/../program.masm"),
+            "relative/program.masm"
+        );
+    }
+}

src/dap_server.rs

@@ -3,7 +3,7 @@ use std::{path::Path, sync::Arc};
 use miden_assembly::{Assembler, DefaultSourceManager, SourceManager};
 use miden_assembly_syntax::diagnostics::{IntoDiagnostic, Report};
 use miden_core::{Word, events::EventId};
-use miden_debug_engine::HybridPackageRegistry;
+use miden_debug_engine::{HybridPackageRegistry, normalize_source_path};
 use miden_debug_types::{Location, SourceFile, SourceManagerExt, SourceSpan};
 use miden_mast_package::{Package, PackageId};
 use miden_package_registry::{PackageProvider, PackageRegistry};
@@ -77,12 +77,8 @@ impl StandaloneDapHost {
             return Some(file);
         }
 
-        let path = location
-            .uri()
-            .as_str()
-            .strip_prefix("file://")
-            .unwrap_or_else(|| location.uri().as_str());
-        self.source_manager.load_file(Path::new(path)).ok()
+        let path = normalize_source_path(location.uri().as_str());
+        self.source_manager.load_file(Path::new(&path)).ok()
     }
 }
 

src/ui/state.rs

@@ -6,7 +6,7 @@ use std::{
 
 use miden_assembly::{DefaultSourceManager, SourceManager};
 use miden_assembly_syntax::diagnostics::Report;
-use miden_debug_engine::DebugQuery;
+use miden_debug_engine::{DebugQuery, normalize_source_path};
 use miden_debug_types::{Location, SourceManagerExt, SourceSpan};
 use miden_mast_package::Package;
 use miden_processor::{
@@ -1279,35 +1279,6 @@ fn source_var_location_is_visible(
     source_paths_match(var_path, current_path, source_path_prefixes) && var_line < current_line
 }
 
-fn normalize_source_path(path: &str) -> String {
-    let path = path.trim();
-    let path = path.strip_prefix("file://").unwrap_or(path);
-    let path = path.replace('\\', "/");
-
-    let is_absolute = path.starts_with('/');
-    let mut parts = Vec::new();
-    for part in path.split('/') {
-        match part {
-            "" | "." => {}
-            ".." => {
-                if parts.last().is_some_and(|last| *last != "..") {
-                    parts.pop();
-                } else {
-                    parts.push(part);
-                }
-            }
-            _ => parts.push(part),
-        }
-    }
-
-    let normalized = parts.join("/");
-    if is_absolute && !normalized.is_empty() {
-        format!("/{normalized}")
-    } else {
-        normalized
-    }
-}
-
 fn strip_source_prefix(path: &str, prefix: &str) -> Option<String> {
     let path = path.trim_start_matches('/');
     let prefix = prefix.trim_start_matches('/').trim_end_matches('/');