diff --git a/codeflash/setup/detector.py b/codeflash/setup/detector.py
index 5a5bb9e5a..a57ef0ad4 100644
--- a/codeflash/setup/detector.py
+++ b/codeflash/setup/detector.py
@@ -310,14 +310,21 @@ def _detect_js_module_root(project_root: Path) -> tuple[Path, str]:
     """Detect JavaScript/TypeScript module root.
 
     Priority:
-    1. package.json "exports" field
-    2. package.json "module" field (ESM)
-    3. package.json "main" field (CJS)
-    4. src/ directory
-    5. lib/ directory
-    6. Project root
+    1. src/, lib/, source/ directories (common source directories)
+    2. package.json "exports" field (if not in build output directory)
+    3. package.json "module" field (ESM, if not in build output directory)
+    4. package.json "main" field (CJS, if not in build output directory)
+    5. Project root
+
+    Build output directories (build/, dist/, out/) are skipped since they contain
+    compiled code, not source files.
 
     """
+    # Check for common source directories first - these are always preferred
+    for src_dir in ["src", "lib", "source"]:
+        if (project_root / src_dir).is_dir():
+            return project_root / src_dir, f"{src_dir}/ directory"
+
     package_json_path = project_root / "package.json"
     package_data: dict[str, Any] = {}
 
@@ -334,32 +341,54 @@ def _detect_js_module_root(project_root: Path) -> tuple[Path, str]:
         entry_path = _extract_entry_path(exports)
         if entry_path:
             parent = Path(entry_path).parent
-            if parent != Path() and parent.as_posix() != "." and (project_root / parent).is_dir():
+            if (
+                parent != Path()
+                and parent.as_posix() != "."
+                and (project_root / parent).is_dir()
+                and not is_build_output_dir(parent)
+            ):
                 return project_root / parent, f'{parent.as_posix()}/ (from package.json "exports")'
 
     # Check module field (ESM)
     module_field = package_data.get("module")
     if module_field and isinstance(module_field, str):
         parent = Path(module_field).parent
-        if parent != Path() and parent.as_posix() != "." and (project_root / parent).is_dir():
+        if (
+            parent != Path()
+            and parent.as_posix() != "."
+            and (project_root / parent).is_dir()
+            and not is_build_output_dir(parent)
+        ):
             return project_root / parent, f'{parent.as_posix()}/ (from package.json "module")'
 
     # Check main field (CJS)
     main_field = package_data.get("main")
     if main_field and isinstance(main_field, str):
         parent = Path(main_field).parent
-        if parent != Path() and parent.as_posix() != "." and (project_root / parent).is_dir():
+        if (
+            parent != Path()
+            and parent.as_posix() != "."
+            and (project_root / parent).is_dir()
+            and not is_build_output_dir(parent)
+        ):
             return project_root / parent, f'{parent.as_posix()}/ (from package.json "main")'
 
-    # Check for common source directories
-    for src_dir in ["src", "lib", "source"]:
-        if (project_root / src_dir).is_dir():
-            return project_root / src_dir, f"{src_dir}/ directory"
-
     # Default to project root
     return project_root, "project root"
 
 
+def is_build_output_dir(path: Path) -> bool:
+    """Check if a path is within a common build output directory.
+
+    Build output directories contain compiled code and should be skipped
+    in favor of source directories.
+
+    """
+    build_dirs = {"build", "dist", "out", ".next", ".nuxt"}
+    parts = path.as_posix().split("/")
+    return any(part in build_dirs for part in parts)
+
+
 def _extract_entry_path(exports: Any) -> str | None:
     """Extract entry path from package.json exports field."""
     if isinstance(exports, str):
diff --git a/tests/test_setup/test_detector.py b/tests/test_setup/test_detector.py
index 45a74d167..f40d758a1 100644
--- a/tests/test_setup/test_detector.py
+++ b/tests/test_setup/test_detector.py
@@ -14,6 +14,7 @@ from codeflash.setup.detector import (
     _find_project_root,
     detect_project,
     has_existing_config,
+    is_build_output_dir,
 )
 
 
@@ -139,15 +140,15 @@ class TestDetectModuleRoot:
         assert "pyproject.toml" in detail
 
     def test_js_detects_from_exports(self, tmp_path):
-        """Should detect module root from package.json exports."""
+        """Should detect module root from package.json exports when no common src dir exists."""
         (tmp_path / "package.json").write_text(json.dumps({
             "name": "test",
-            "exports": {".": "./src/index.js"}
+            "exports": {".": "./packages/core/index.js"}
         }))
-        (tmp_path / "src").mkdir()
+        (tmp_path / "packages" / "core").mkdir(parents=True)
 
         module_root, detail = _detect_js_module_root(tmp_path)
-        assert module_root == tmp_path / "src"
+        assert module_root == tmp_path / "packages" / "core"
         assert "exports" in detail
 
     def test_js_detects_src_convention(self, tmp_path):
@@ -158,6 +159,214 @@ class TestDetectModuleRoot:
         module_root, detail = _detect_js_module_root(tmp_path)
         assert module_root == tmp_path / "src"
 
+    def test_js_prefers_src_over_build_src(self, tmp_path):
+        """Should prefer src/ over build/src/ even when package.json points to build/."""
+        (tmp_path / "package.json").write_text(json.dumps({
+            "name": "test",
+            "main": "build/src/index.js",
+            "module": "build/src/index.js"
+        }))
+        (tmp_path / "src").mkdir()
+        (tmp_path / "build" / "src").mkdir(parents=True)
+
+        module_root, detail = _detect_js_module_root(tmp_path)
+        assert module_root == tmp_path / "src"
+        assert "src/ directory" in detail
+
+    def test_js_skips_build_dir_from_main(self, tmp_path):
+        """Should skip build output directories from package.json main field."""
+        (tmp_path / "package.json").write_text(json.dumps({
+            "name": "test",
+            "main": "build/index.js"
+        }))
+        (tmp_path / "build").mkdir()
+
+        module_root, detail = _detect_js_module_root(tmp_path)
+        assert module_root == tmp_path
+        assert "project root" in detail
+
+    def test_js_skips_dist_dir_from_exports(self, tmp_path):
+        """Should skip dist output directories from package.json exports field."""
+        (tmp_path / "package.json").write_text(json.dumps({
+            "name": "test",
+            "exports": {".": "./dist/index.js"}
+        }))
+        (tmp_path / "dist").mkdir()
+
+        module_root, detail = _detect_js_module_root(tmp_path)
+        assert module_root == tmp_path
+        assert "project root" in detail
+
+    def test_js_skips_out_dir_from_module(self, tmp_path):
+        """Should skip out output directories from package.json module field."""
+        (tmp_path / "package.json").write_text(json.dumps({
+            "name": "test",
+            "module": "out/esm/index.js"
+        }))
+        (tmp_path / "out" / "esm").mkdir(parents=True)
+
+        module_root, detail = _detect_js_module_root(tmp_path)
+        assert module_root == tmp_path
+        assert "project root" in detail
+
+    def test_js_prefers_lib_over_build_dir(self, tmp_path):
+        """Should prefer lib/ over build output directories."""
+        (tmp_path / "package.json").write_text(json.dumps({
+            "name": "test",
+            "main": "dist/index.js"
+        }))
+        (tmp_path / "lib").mkdir()
+        (tmp_path / "dist").mkdir()
+
+        module_root, detail = _detect_js_module_root(tmp_path)
+        assert module_root == tmp_path / "lib"
+        assert "lib/ directory" in detail
+
+    def test_js_prefers_source_over_build_dir(self, tmp_path):
+        """Should prefer source/ over build output directories."""
+        (tmp_path / "package.json").write_text(json.dumps({
+            "name": "test",
+            "main": "build/index.js"
+        }))
+        (tmp_path / "source").mkdir()
+        (tmp_path / "build").mkdir()
+
+        module_root, detail = _detect_js_module_root(tmp_path)
+        assert module_root == tmp_path / "source"
+        assert "source/ directory" in detail
+
+    def test_js_falls_back_to_valid_exports_path(self, tmp_path):
+        """Should use exports path when no common source dirs exist and path is not build output."""
+        (tmp_path / "package.json").write_text(json.dumps({
+            "name": "test",
+            "exports": {".": "./packages/core/index.js"}
+        }))
+        (tmp_path / "packages" / "core").mkdir(parents=True)
+
+        module_root, detail = _detect_js_module_root(tmp_path)
+        assert module_root == tmp_path / "packages" / "core"
+        assert "exports" in detail
+
+    def test_js_falls_back_to_valid_main_path(self, tmp_path):
+        """Should use main path when no common source dirs exist and path is not build output."""
+        (tmp_path / "package.json").write_text(json.dumps({
+            "name": "test",
+            "main": "packages/main/index.js"
+        }))
+        (tmp_path / "packages" / "main").mkdir(parents=True)
+
+        module_root, detail = _detect_js_module_root(tmp_path)
+        assert module_root == tmp_path / "packages" / "main"
+        assert "main" in detail
+
+    def test_js_falls_back_to_valid_module_path(self, tmp_path):
+        """Should use module path when no common source dirs exist and path is not build output."""
+        (tmp_path / "package.json").write_text(json.dumps({
+            "name": "test",
+            "module": "esm/index.js"
+        }))
+        (tmp_path / "esm").mkdir()
+
+        module_root, detail = _detect_js_module_root(tmp_path)
+        assert module_root == tmp_path / "esm"
+        assert "module" in detail
+
+    def test_js_returns_project_root_when_all_paths_are_build_output(self, tmp_path):
+        """Should return project root when all package.json paths point to build outputs."""
+        (tmp_path / "package.json").write_text(json.dumps({
+            "name": "test",
+            "main": "dist/cjs/index.js",
+            "module": "dist/esm/index.js",
+            "exports": {".": "./build/index.js"}
+        }))
+        (tmp_path / "dist" / "cjs").mkdir(parents=True)
+        (tmp_path / "dist" / "esm").mkdir(parents=True)
+        (tmp_path / "build").mkdir()
+
+        module_root, detail = _detect_js_module_root(tmp_path)
+        assert module_root == tmp_path
+        assert "project root" in detail
+
+    def test_js_handles_malformed_package_json(self, tmp_path):
+        """Should handle malformed package.json gracefully."""
+        (tmp_path / "package.json").write_text("{ invalid json }")
+
+        module_root, detail = _detect_js_module_root(tmp_path)
+        assert module_root == tmp_path
+        assert "project root" in detail
+
+
+class TestIsBuildOutputDir:
+    """Tests for is_build_output_dir function."""
+
+    def test_detects_build_dir(self):
+        """Should detect build/ as build output."""
+        from pathlib import Path
+        assert is_build_output_dir(Path("build"))
+        assert is_build_output_dir(Path("build/src"))
+        assert is_build_output_dir(Path("build/src/index.js"))
+
+    def test_detects_dist_dir(self):
+        """Should detect dist/ as build output."""
+        from pathlib import Path
+        assert is_build_output_dir(Path("dist"))
+        assert is_build_output_dir(Path("dist/esm"))
+        assert is_build_output_dir(Path("dist/cjs/index.js"))
+
+    def test_detects_out_dir(self):
+        """Should detect out/ as build output."""
+        from pathlib import Path
+        assert is_build_output_dir(Path("out"))
+        assert is_build_output_dir(Path("out/src"))
+
+    def test_detects_next_dir(self):
+        """Should detect .next/ as build output."""
+        from pathlib import Path
+        assert is_build_output_dir(Path(".next"))
+        assert is_build_output_dir(Path(".next/static"))
+
+    def test_detects_nuxt_dir(self):
+        """Should detect .nuxt/ as build output."""
+        from pathlib import Path
+        assert is_build_output_dir(Path(".nuxt"))
+        assert is_build_output_dir(Path(".nuxt/dist"))
+
+    def test_detects_nested_build_dir(self):
+        """Should detect build dir nested in path."""
+        from pathlib import Path
+        assert is_build_output_dir(Path("packages/build/index.js"))
+        assert is_build_output_dir(Path("foo/dist/bar"))
+
+    def test_does_not_detect_src(self):
+        """Should not detect src/ as build output."""
+        from pathlib import Path
+        assert not is_build_output_dir(Path("src"))
+        assert not is_build_output_dir(Path("src/index.js"))
+
+    def test_does_not_detect_lib(self):
+        """Should not detect lib/ as build output."""
+        from pathlib import Path
+        assert not is_build_output_dir(Path("lib"))
+        assert not is_build_output_dir(Path("lib/utils"))
+
+    def test_does_not_detect_source(self):
+        """Should not detect source/ as build output."""
+        from pathlib import Path
+        assert not is_build_output_dir(Path("source"))
+
+    def test_does_not_detect_packages(self):
+        """Should not detect packages/ as build output."""
+        from pathlib import Path
+        assert not is_build_output_dir(Path("packages"))
+        assert not is_build_output_dir(Path("packages/core"))
+
+    def test_does_not_detect_similar_names(self):
+        """Should not detect directories with similar but different names."""
+        from pathlib import Path
+        assert not is_build_output_dir(Path("builder"))
+        assert not is_build_output_dir(Path("distribution"))
+        assert not is_build_output_dir(Path("output"))
+
 
 class TestDetectTestsRoot:
     """Tests for tests root detection."""
diff --git a/tests/test_setup/test_e2e_setup.py b/tests/test_setup/test_e2e_setup.py
index e10fa6c93..34fe45949 100644
--- a/tests/test_setup/test_e2e_setup.py
+++ b/tests/test_setup/test_e2e_setup.py
@@ -857,6 +857,48 @@ class TestE2ECLIFlags:
         # Should complete without error
         _handle_show_config()
 
+    def test_show_config_displays_config_path_when_saved(self, project_with_existing_config, monkeypatch):
+        """Should display config file path when saved config exists."""
+        monkeypatch.chdir(project_with_existing_config)
+
+        # Track what gets printed
+        printed_messages = []
+
+        def mock_print(msg="", *args, **kwargs):
+            printed_messages.append(str(msg))
+
+        from codeflash.cli_cmds import console
+        monkeypatch.setattr(console.console, "print", mock_print)
+
+        from codeflash.cli_cmds.cli import _handle_show_config
+        _handle_show_config()
+
+        # Verify config path is displayed
+        all_output = "\n".join(printed_messages)
+        assert "pyproject.toml" in all_output
+        assert "Config file:" in all_output
+
+    def test_show_config_no_path_when_auto_detected(self, python_src_layout, monkeypatch):
+        """Should not display config file path when config is auto-detected."""
+        monkeypatch.chdir(python_src_layout)
+
+        # Track what gets printed
+        printed_messages = []
+
+        def mock_print(msg="", *args, **kwargs):
+            printed_messages.append(str(msg))
+
+        from codeflash.cli_cmds import console
+        monkeypatch.setattr(console.console, "print", mock_print)
+
+        from codeflash.cli_cmds.cli import _handle_show_config
+        _handle_show_config()
+
+        # Verify no config path line is displayed
+        all_output = "\n".join(printed_messages)
+        assert "Config file:" not in all_output
+        assert "Auto-detected" in all_output
+
     def test_reset_config_removes_from_pyproject(self, project_with_existing_config, monkeypatch):
         """Should remove codeflash config from pyproject.toml."""
         monkeypatch.chdir(project_with_existing_config)