diff --git a/tests/test_app_controller_result.py b/tests/test_app_controller_result.py
new file mode 100644
index 00000000..759d1a23
--- /dev/null
+++ b/tests/test_app_controller_result.py
@@ -0,0 +1,112 @@
+"""
+Tests for the data-oriented error handling convention applied to src/app_controller.py.
+
+This file verifies the contract that the 32 INTERNAL_BROAD_CATCH + 8 INTERNAL_SILENT_SWALLOW
++ 4 INTERNAL_RETHROW + 1 INTERNAL_OPTIONAL_RETURN sites in src/app_controller.py are migrated
+to the Result[T] pattern (per conductor/code_styleguides/error_handling.md).
+
+The tests are pattern templates:
+- test_offload_entry_payload_returns_dict - the _offload_entry_payload helper returns a dict
+  (the existing test for the regression fix is in test_app_controller_offloading.py; this
+  one is a shape check).
+- test_migrated_method_returns_result_on_success - methods migrated to Result[T] return
+  Result[data=...] with no errors on the success path.
+- test_migrated_method_returns_result_with_error_on_failure - methods migrated to Result[T]
+  return Result with errors=... on the failure path.
+- test_app_controller_does_not_use_broad_except - static check: src/app_controller.py
+  has no `except Exception:` clauses left (all 32 are migrated to specific exceptions).
+- test_offload_entry_payload_preserves_unchanged_payload - verifies the no-op path for
+  entries without tool_call or tool_result kinds.
+"""
+import pytest
+from unittest.mock import MagicMock, patch
+from src.app_controller import AppController
+from src.result_types import Result, ErrorInfo, ErrorKind
+
+
+def test_offload_entry_payload_returns_dict():
+ """
+ Shape contract: _offload_entry_payload returns a dict.
+ The actual happy-path and error-path tests are in test_app_controller_offloading.py.
+ """
+ with patch("src.app_controller.performance_monitor.PerformanceMonitor"):
+  ctrl = AppController()
+  out = ctrl._offload_entry_payload({"kind": "request", "payload": {"message": "hi"}, "ts": "12:00:00"})
+ assert isinstance(out, dict)
+ assert out["kind"] == "request"
+ assert out["payload"]["message"] == "hi"
+
+
+def test_migrated_method_returns_result_on_success():
+ """
+ Pattern template: methods migrated to Result[T] return Result[data=...] with no errors
+ on the success path. The 5 callback-handler sites (Batch 1) include _handle_custom_callback
+ and _handle_click; both return Result[None] after migration.
+ """
+ from src.app_controller import _handle_custom_callback
+ controller = MagicMock()
+ controller._predefined_callbacks = {}
+ # Use a no-op callback so the body runs without error
+ task = {"callback": (lambda: None), "args": []}
+ result = _handle_custom_callback(controller, task)
+ assert isinstance(result, Result)
+ assert result.ok is True
+ assert result.errors == []
+
+
+def test_migrated_method_returns_result_with_error_on_failure():
+ """
+ Pattern template: methods migrated to Result[T] return Result with errors=... when
+ the underlying call raises. The migrated callback sites catch the specific exception
+ (e.g. TypeError, ValueError) and convert it to ErrorInfo.
+ """
+ from src.app_controller import _handle_custom_callback
+ controller = MagicMock()
+ controller._predefined_callbacks = {}
+ # Callback that raises a specific exception
+ def bad_cb():
+  raise ValueError("simulated failure")
+ task = {"callback": bad_cb, "args": []}
+ result = _handle_custom_callback(controller, task)
+ assert isinstance(result, Result)
+ assert result.ok is False
+ assert any("ValueError" in e.message or "simulated failure" in e.message for e in result.errors)
+
+
+def test_app_controller_does_not_use_broad_except():
+ """
+ Static check: src/app_controller.py has no `except Exception:` clauses left
+ (all 32 are migrated to specific exceptions).
+ """
+ import ast
+ import pathlib
+ src = pathlib.Path("src/app_controller.py").read_text(encoding="utf-8")
+ tree = ast.parse(src)
+ broad_catch_lines: list[int] = []
+ for node in ast.walk(tree):
+  if isinstance(node, ast.ExceptHandler) and node.type is not None:
+   # `except Exception:` (bare Exception class as the type)
+   if isinstance(node.type, ast.Name) and node.type.id == "Exception":
+    broad_catch_lines.append(node.lineno)
+   # `except (Exception,):` or `except (Exception, Foo):`
+   elif isinstance(node.type, ast.Tuple):
+    for elt in node.type.elts:
+     if isinstance(elt, ast.Name) and elt.id == "Exception":
+      broad_catch_lines.append(node.lineno)
+      break
+ assert broad_catch_lines == [], (
+  f"src/app_controller.py still has {len(broad_catch_lines)} `except Exception` clauses at lines {broad_catch_lines}. "
+  f"All 32 INTERNAL_BROAD_CATCH sites must be migrated to specific exceptions."
+ )
+
+
+def test_offload_entry_payload_preserves_unchanged_payload():
+ """
+ Verifies the no-op path: entries without tool_call or tool_result kinds are returned
+ with the payload unchanged (no [REF:...] rewriting).
+ """
+ with patch("src.app_controller.performance_monitor.PerformanceMonitor"):
+  ctrl = AppController()
+  entry = {"kind": "request", "payload": {"message": "hi"}, "ts": "12:00:00"}
+  out = ctrl._offload_entry_payload(entry)
+ assert out == entry