diff --git a/crates/worker-runtime/src/working_directory.rs b/crates/worker-runtime/src/working_directory.rs
index 1257af26..147dfb77 100644
--- a/crates/worker-runtime/src/working_directory.rs
+++ b/crates/worker-runtime/src/working_directory.rs
@@ -484,6 +484,18 @@ impl RuntimeGitMaterializer {
         Ok(binding)
     }
 
+    fn validate_plain_http_source(
+        request: &WorkingDirectoryRequest,
+    ) -> Result<(), WorkingDirectoryDiagnostic> {
+        if url::Url::parse(&request.repository.source.uri).is_ok_and(|url| url.scheme() == "http") {
+            return Err(WorkingDirectoryDiagnostic::new(
+                "working_directory_repository_plain_http_unsupported",
+                "plain HTTP Repository sources are not executable; register an HTTPS or SSH source instead",
+            ));
+        }
+        Ok(())
+    }
+
     fn validate_request(
         request: &WorkingDirectoryRequest,
     ) -> Result<(), WorkingDirectoryDiagnostic> {
@@ -499,6 +511,7 @@ impl RuntimeGitMaterializer {
                 "the configured Repository provider is unsupported",
             ));
         }
+        Self::validate_plain_http_source(request)?;
         if matches!(
             request.repository.source.kind,
             workspace_api::RepositorySourceKind::Https | workspace_api::RepositorySourceKind::Ssh
@@ -540,20 +553,10 @@ impl RuntimeGitMaterializer {
                 validate_ssh_materialization_access(ssh)?;
             }
             workspace_api::RepositorySourceKind::Invalid => {
-                let is_plain_http = url::Url::parse(&request.repository.source.uri)
-                    .is_ok_and(|url| url.scheme() == "http");
-                let (code, message) = if is_plain_http {
-                    (
-                        "working_directory_repository_plain_http_unsupported",
-                        "plain HTTP Repository sources are not executable; register an HTTPS or SSH source instead",
-                    )
-                } else {
-                    (
-                        "working_directory_repository_source_invalid",
-                        "configured Repository source is invalid and cannot be materialized",
-                    )
-                };
-                return Err(WorkingDirectoryDiagnostic::new(code, message));
+                return Err(WorkingDirectoryDiagnostic::new(
+                    "working_directory_repository_source_invalid",
+                    "configured Repository source is invalid and cannot be materialized",
+                ));
             }
         }
         validate_selector(request.repository.selector.as_deref().unwrap_or("HEAD"))
@@ -627,6 +630,7 @@ impl RuntimeGitMaterializer {
         request: &WorkingDirectoryRequest,
     ) -> Result<WorkingDirectoryBinding, WorkingDirectoryDiagnostic> {
         validate_working_directory_id(&working_directory_id)?;
+        Self::validate_plain_http_source(request)?;
         let request =
             self.request_with_authorized_repository_access(&working_directory_id, request)?;
         Self::validate_request(&request)?;
@@ -3812,6 +3816,34 @@ mod tests {
             "plain HTTP rejection must occur before invoking Git"
         );
 
+        for (offset, kind) in [
+            workspace_api::RepositorySourceKind::LocalPath,
+            workspace_api::RepositorySourceKind::File,
+            workspace_api::RepositorySourceKind::Https,
+        ]
+        .into_iter()
+        .enumerate()
+        {
+            let mut mismatched_http = request(repo.path());
+            mismatched_http.repository.source = workspace_api::RepositorySource {
+                kind,
+                uri: "http://example.test/repo.git".to_string(),
+            };
+            let git_invocations_before = test_repository_git_invocation_count();
+            let error = materializer
+                .materialize(&worker_ref(4 + offset as u64), &mismatched_http)
+                .expect_err("plain HTTP URI must fail regardless of its declared source kind");
+            assert_eq!(
+                error.code,
+                "working_directory_repository_plain_http_unsupported"
+            );
+            assert_eq!(
+                test_repository_git_invocation_count(),
+                git_invocations_before,
+                "mismatched plain HTTP source must fail before invoking Git"
+            );
+        }
+
         let mut ssh = request(repo.path());
         ssh.repository.source = workspace_api::RepositorySource {
             kind: workspace_api::RepositorySourceKind::Ssh,
diff --git a/crates/workspace-server/src/repository_access.rs b/crates/workspace-server/src/repository_access.rs
index 9dd302a4..7bea3352 100644
--- a/crates/workspace-server/src/repository_access.rs
+++ b/crates/workspace-server/src/repository_access.rs
@@ -1980,6 +1980,17 @@ mod tests {
         let error = validate_repository_access_source("remote", &source).unwrap_err();
         assert!(error.to_string().contains("unsupported plain HTTP"));
         assert!(error.to_string().contains("HTTPS or SSH"));
+
+        let mismatched = workspace_api::RepositorySource {
+            kind: workspace_api::RepositorySourceKind::Https,
+            uri: "http://git.example.test/team/project.git".to_string(),
+        };
+        let error = validate_repository_access_source("remote", &mismatched).unwrap_err();
+        assert!(
+            error
+                .to_string()
+                .contains("repository_source_plain_http_unsupported")
+        );
     }
 
     #[test]
diff --git a/crates/workspace-server/src/repository_source.rs b/crates/workspace-server/src/repository_source.rs
index 2db070a3..7d3bf407 100644
--- a/crates/workspace-server/src/repository_source.rs
+++ b/crates/workspace-server/src/repository_source.rs
@@ -113,8 +113,7 @@ pub fn classify_legacy_repository_source(value: &str) -> RepositorySource {
 }
 
 pub(crate) fn is_plain_http_repository_source(source: &RepositorySource) -> bool {
-    source.kind == RepositorySourceKind::Invalid
-        && Url::parse(&source.uri).is_ok_and(|url| url.scheme() == "http")
+    Url::parse(&source.uri).is_ok_and(|url| url.scheme() == "http")
 }
 
 pub fn repository_source_fingerprint(source: &RepositorySource) -> String {