diff --git a/codex-rs/core/src/external_agent_config.rs b/codex-rs/core/src/external_agent_config.rs
index b39fba7c87..a688fce12a 100644
--- a/codex-rs/core/src/external_agent_config.rs
+++ b/codex-rs/core/src/external_agent_config.rs
@@ -3,6 +3,7 @@ use crate::plugins::PluginId;
 use crate::plugins::PluginInstallRequest;
 use crate::plugins::PluginsManager;
 use crate::plugins::add_marketplace;
+use crate::plugins::validate_marketplace_add_source;
 use codex_utils_absolute_path::AbsolutePathBuf;
 use serde_json::Value as JsonValue;
 use std::collections::BTreeMap;
@@ -536,6 +537,14 @@ fn extract_plugin_migration_details(
     settings: &JsonValue,
     configured_enabled_plugins: &HashSet<String>,
 ) -> Option<MigrationDetails> {
+    let loadable_marketplaces = collect_marketplace_import_sources(settings)
+        .into_iter()
+        .filter_map(|(marketplace_name, source)| {
+            validate_marketplace_add_source(&source.source, source.ref_name)
+                .ok()
+                .map(|()| marketplace_name)
+        })
+        .collect::<HashSet<_>>();
     let mut plugins = BTreeMap::new();
     for plugin_id in collect_enabled_plugins(settings)
         .into_iter()
@@ -544,6 +553,9 @@ fn extract_plugin_migration_details(
         let Ok(plugin_id) = PluginId::parse(&plugin_id) else {
             continue;
         };
+        if !loadable_marketplaces.contains(&plugin_id.marketplace_name) {
+            continue;
+        }
         let plugin_group = plugins
             .entry(plugin_id.marketplace_name.clone())
             .or_insert_with(|| PluginsMigration {
diff --git a/codex-rs/core/src/external_agent_config_tests.rs b/codex-rs/core/src/external_agent_config_tests.rs
index c343688560..bdcf21ed95 100644
--- a/codex-rs/core/src/external_agent_config_tests.rs
+++ b/codex-rs/core/src/external_agent_config_tests.rs
@@ -418,6 +418,11 @@ fn detect_home_lists_enabled_plugins_from_settings() {
             "formatter@acme-tools": true,
             "deployer@acme-tools": true,
             "analyzer@security-plugins": false
+          },
+          "extraKnownMarketplaces": {
+            "acme-tools": {
+              "source": "acme-corp/claude-plugins"
+            }
           }
         }"#,
     )
@@ -464,6 +469,11 @@ fn detect_repo_skips_plugins_that_are_already_enabled_in_codex() {
           "enabledPlugins": {
             "formatter@acme-tools": true,
             "deployer@acme-tools": true
+          },
+          "extraKnownMarketplaces": {
+            "acme-tools": {
+              "source": "acme-corp/claude-plugins"
+            }
           }
         }"#,
     )
@@ -516,6 +526,59 @@ async fn import_plugins_requires_details() {
     assert_eq!(err.to_string(), "plugins migration item is missing details");
 }
 
+#[test]
+fn detect_home_skips_plugins_without_marketplace_source() {
+    let (_root, claude_home, codex_home) = fixture_paths();
+    fs::create_dir_all(&claude_home).expect("create claude home");
+    fs::write(
+        claude_home.join("settings.json"),
+        r#"{
+          "enabledPlugins": {
+            "formatter@acme-tools": true
+          }
+        }"#,
+    )
+    .expect("write settings");
+
+    let items = service_for_paths(claude_home, codex_home)
+        .detect(ExternalAgentConfigDetectOptions {
+            include_home: true,
+            cwds: None,
+        })
+        .expect("detect");
+
+    assert_eq!(items, Vec::<ExternalAgentConfigMigrationItem>::new());
+}
+
+#[test]
+fn detect_home_skips_plugins_with_invalid_marketplace_source() {
+    let (_root, claude_home, codex_home) = fixture_paths();
+    fs::create_dir_all(&claude_home).expect("create claude home");
+    fs::write(
+        claude_home.join("settings.json"),
+        r#"{
+          "enabledPlugins": {
+            "formatter@acme-tools": true
+          },
+          "extraKnownMarketplaces": {
+            "acme-tools": {
+              "source": "github"
+            }
+          }
+        }"#,
+    )
+    .expect("write settings");
+
+    let items = service_for_paths(claude_home, codex_home)
+        .detect(ExternalAgentConfigDetectOptions {
+            include_home: true,
+            cwds: None,
+        })
+        .expect("detect");
+
+    assert_eq!(items, Vec::<ExternalAgentConfigMigrationItem>::new());
+}
+
 #[tokio::test]
 async fn import_plugins_requires_source_marketplace_details() {
     let (_root, claude_home, codex_home) = fixture_paths();
diff --git a/codex-rs/core/src/plugins/marketplace_add.rs b/codex-rs/core/src/plugins/marketplace_add.rs
index 49c1c2e565..2ef11106f8 100644
--- a/codex-rs/core/src/plugins/marketplace_add.rs
+++ b/codex-rs/core/src/plugins/marketplace_add.rs
@@ -56,6 +56,13 @@ pub async fn add_marketplace(
         .map_err(|err| MarketplaceAddError::Internal(format!("failed to add marketplace: {err}")))?
 }
 
+pub fn validate_marketplace_add_source(
+    source: &str,
+    ref_name: Option<String>,
+) -> Result<(), MarketplaceAddError> {
+    parse_marketplace_source(source, ref_name).map(|_| ())
+}
+
 fn add_marketplace_sync(
     codex_home: &Path,
     request: MarketplaceAddRequest,
diff --git a/codex-rs/core/src/plugins/mod.rs b/codex-rs/core/src/plugins/mod.rs
index 7ffb80b449..5b46109bce 100644
--- a/codex-rs/core/src/plugins/mod.rs
+++ b/codex-rs/core/src/plugins/mod.rs
@@ -63,6 +63,7 @@ pub use marketplace_add::MarketplaceAddError;
 pub use marketplace_add::MarketplaceAddOutcome;
 pub use marketplace_add::MarketplaceAddRequest;
 pub use marketplace_add::add_marketplace;
+pub use marketplace_add::validate_marketplace_add_source;
 pub use remote::RemotePluginFetchError;
 pub use remote::fetch_remote_featured_plugin_ids;
 pub(crate) use render::render_explicit_plugin_instructions;