diff --git a/backend/app/modules/impl_tracker/domain/entities.py b/backend/app/modules/impl_tracker/domain/entities.py
index e69de29..cb3db3f 100644
--- a/backend/app/modules/impl_tracker/domain/entities.py
+++ b/backend/app/modules/impl_tracker/domain/entities.py
@@ -0,0 +1,18 @@
+from dataclasses import dataclass
+from datetime import datetime
+
+
+@dataclass
+class ImplProgress:
+    module_id: str
+    percentage: float    # 0-100
+    source: str          # auto, llm, manual
+    evaluated_at: datetime
+
+
+@dataclass
+class CodeStructure:
+    root_path: str
+    directories: list[str]
+    files: list[str]
+    matched_modules: list[str]
diff --git a/backend/app/modules/impl_tracker/infrastructure/code_scanner.py b/backend/app/modules/impl_tracker/infrastructure/code_scanner.py
new file mode 100644
index 0000000..d759725
--- /dev/null
+++ b/backend/app/modules/impl_tracker/infrastructure/code_scanner.py
@@ -0,0 +1,33 @@
+from pathlib import Path
+
+from app.modules.impl_tracker.domain.entities import CodeStructure
+from app.modules.scanner.domain.entities import ScanResult
+
+
+def scan_code_directory(code_dir: str, scan_result: ScanResult) -> CodeStructure:
+    root = Path(code_dir)
+    if not root.is_dir():
+        return CodeStructure(root_path=code_dir, directories=[], files=[], matched_modules=[])
+
+    directories = []
+    files = []
+    for p in sorted(root.rglob("*")):
+        rel = str(p.relative_to(root))
+        if p.is_dir():
+            directories.append(rel)
+        elif p.is_file():
+            files.append(rel)
+
+    # Match modules by checking if code_root from CodebaseAlignment exists
+    matched = []
+    for alignment in scan_result.codebase_alignments:
+        code_root = alignment.code_root
+        if (root / code_root).exists():
+            matched.append(alignment.module_id)
+
+    return CodeStructure(
+        root_path=code_dir,
+        directories=directories,
+        files=files,
+        matched_modules=matched,
+    )
diff --git a/backend/app/modules/impl_tracker/infrastructure/llm_client.py b/backend/app/modules/impl_tracker/infrastructure/llm_client.py
new file mode 100644
index 0000000..477a9af
--- /dev/null
+++ b/backend/app/modules/impl_tracker/infrastructure/llm_client.py
@@ -0,0 +1,4 @@
+class LlmClient:
+    def evaluate_module(self, module_design: str, module_code: str) -> float:
+        """Stub: returns 0.0. Real implementation would call LLM API."""
+        return 0.0