diff --git a/CHANGELOG.md b/CHANGELOG.md
index 8b758fa6f..af2bf27e1 100644
--- a/CHANGELOG.md
+++ b/CHANGELOG.md
@@ -55,6 +55,13 @@ The format follows [Keep a Changelog](https://keepachangelog.com/en/1.1.0/).
   sets ``CLEVERAGENTS_CONFIG_PATH`` for ``ConfigService`` to pick up, and ``-v``
   (repeatable count) maps to the appropriate ``structlog`` log level.
 
+- **Add regression test for ActorRegistry.add() nested provider/model extraction** (#4321):
+  Added BDD regression test confirming that provider and model are correctly
+  extracted from nested `actors.<name>.config` blocks when `type` is only at
+  the nested level and `name` uses the `local/` namespace prefix. This
+  scenario was previously fixed in #4300; the test ensures the fix remains
+  in place and prevents future regressions.
+
 - **Actor configuration validation incorrectly requires top-level provider field** (#4300): 
    Actor configuration in V3 is now obtained from the nested configuration 
    parameter, according to the specification.
diff --git a/features/actor_registry_spec_yaml.feature b/features/actor_registry_spec_yaml.feature
index b3443c090..a1f58d9ae 100644
--- a/features/actor_registry_spec_yaml.feature
+++ b/features/actor_registry_spec_yaml.feature
@@ -21,6 +21,13 @@ Feature: ActorRegistry.add() accepts spec-compliant actor YAML formats
     Then the actor should be registered with provider "anthropic" and model "claude-3"
     And the registered actor should exist in the actor service
 
+  @tdd_issue @tdd_issue_4321 @tdd_issue_4300
+  Scenario: registry.add() with nested-only type extracts provider/model from nested config
+    When I add a YAML with type only in nested actors map and provider/model in nested config
+    Then the actor should be registered with provider "custom" and model "fpga-model"
+    And the registered actor name should be "local/fpga-strategist"
+    And the registered actor should exist in the actor service
+
   # ── actors: map with unsafe flag ───────────────────────────────────
 
   Scenario: registry.add() preserves unsafe flag from nested spec-compliant config
diff --git a/features/steps/actor_registry_spec_yaml_steps.py b/features/steps/actor_registry_spec_yaml_steps.py
index aefacc0cd..78a7e1696 100644
--- a/features/steps/actor_registry_spec_yaml_steps.py
+++ b/features/steps/actor_registry_spec_yaml_steps.py
@@ -143,6 +143,23 @@ def step_add_actors_separate(context: Context) -> None:
     context.spec_result = context.spec_registry.add(yaml_text)
 
 
+@when(
+    "I add a YAML with type only in nested actors map and provider/model in nested config"
+)
+def step_add_nested_type_only(context: Context) -> None:
+    yaml_text = (
+        "name: local/fpga-strategist\n"
+        "description: An FPGA strategist agent\n"
+        "actors:\n"
+        "  fpga-strategist:\n"
+        "    type: llm\n"
+        "    config:\n"
+        "      provider: custom\n"
+        "      model: fpga-model\n"
+    )
+    context.spec_result = context.spec_registry.add(yaml_text)
+
+
 @when("I add a spec-compliant YAML with actors map and unsafe flag")
 def step_add_actors_unsafe(context: Context) -> None:
     yaml_text = (