diff --git a/backend/app/modules/scanner/infrastructure/parsers/md_parser.py b/backend/app/modules/scanner/infrastructure/parsers/md_parser.py
index e69de29..8e873f2 100644
--- a/backend/app/modules/scanner/infrastructure/parsers/md_parser.py
+++ b/backend/app/modules/scanner/infrastructure/parsers/md_parser.py
@@ -0,0 +1,160 @@
+"""Markdown parser — extracts YAML frontmatter and produces DesignDocument + specialized entities."""
+
+from __future__ import annotations
+
+import re
+from pathlib import Path
+from typing import Any
+
+import yaml
+
+from app.modules.design.domain.entities import (
+    ADR,
+    DesignDocument,
+    Domain,
+    ModuleBoundaryRule,
+    OperationalBaseline,
+    ReleasePlan,
+    RuntimeTopology,
+    ScopeAndGoals,
+    SolutionLayer,
+    SystemContext,
+)
+
+
+_FRONTMATTER_RE = re.compile(r"^---\s*\n(.*?)\n---\s*\n", re.DOTALL)
+
+
+class MdParser:
+    """Parse Markdown file and return dict mapping entity type name to list of instances.
+
+    Keys: 'design_documents', 'scope_and_goals', 'system_context', etc.
+    """
+
+    def parse(self, file_path: Path) -> dict[str, list[Any]]:
+        try:
+            content = file_path.read_text(encoding="utf-8")
+        except Exception:
+            return {}
+
+        match = _FRONTMATTER_RE.match(content)
+        if not match:
+            return {}
+
+        try:
+            frontmatter = yaml.safe_load(match.group(1))
+        except Exception:
+            return {}
+
+        if not isinstance(frontmatter, dict):
+            return {}
+
+        doc_id = frontmatter.get("doc_id", "")
+        if not doc_id:
+            return {}
+
+        title = frontmatter.get("title", "")
+        version = frontmatter.get("version", "")
+        status = frontmatter.get("status", "")
+        owners = frontmatter.get("owners", []) or []
+        upstream = frontmatter.get("upstream", []) or []
+        downstream = frontmatter.get("downstream", []) or []
+
+        # Ensure list types
+        if not isinstance(owners, list):
+            owners = [owners]
+        if not isinstance(upstream, list):
+            upstream = [upstream]
+        if not isinstance(downstream, list):
+            downstream = [downstream]
+
+        design_doc = DesignDocument(
+            doc_id=doc_id,
+            title=title,
+            version=str(version),
+            status=status,
+            owners=owners,
+            upstream=upstream,
+            downstream=downstream,
+            file_path=str(file_path),
+        )
+
+        result: dict[str, list[Any]] = {"design_documents": [design_doc]}
+
+        # Body content after frontmatter
+        body = content[match.end():].strip()
+        fname = file_path.name.lower()
+        fpath_str = str(file_path).lower()
+
+        # Specialized entity detection
+        if "scope-and-goals" in fname or "scope_and_goals" in fname:
+            result["scope_and_goals"] = [ScopeAndGoals(
+                doc_id=doc_id,
+                title=title,
+                core_problem="",
+                users="",
+                constraints="",
+            )]
+
+        elif "system-context" in fname or "system_context" in fname:
+            result["system_context"] = [SystemContext(
+                doc_id=doc_id,
+                title=title,
+                content=body,
+            )]
+
+        elif "solution-layering" in fname or "solution_layering" in fname:
+            result["solution_layer"] = [SolutionLayer(
+                doc_id=doc_id,
+                title=title,
+                content=body,
+            )]
+
+        elif "module-boundary" in fname or "module_boundary" in fname:
+            result["module_boundary_rule"] = [ModuleBoundaryRule(
+                doc_id=doc_id,
+                title=title,
+                content=body,
+            )]
+
+        elif "runtime-topology" in fname or "runtime_topology" in fname:
+            result["runtime_topology"] = [RuntimeTopology(
+                doc_id=doc_id,
+                title=title,
+                content=body,
+            )]
+
+        elif "operational-baseline" in fname or "operational_baseline" in fname:
+            result["operational_baseline"] = [OperationalBaseline(
+                doc_id=doc_id,
+                title=title,
+                content=body,
+            )]
+
+        elif "release-and-rollback" in fname or "release_and_rollback" in fname:
+            result["release_plan"] = [ReleasePlan(
+                doc_id=doc_id,
+                title=title,
+                content=body,
+            )]
+
+        elif "domain-overview" in fname or "domain_overview" in fname:
+            # Extract domain name from parent directory
+            domain_name = file_path.parent.name
+            result["domains"] = [Domain(
+                domain_name=domain_name,
+                overview=body,
+                modules=[],
+                entities=[],
+            )]
+
+        elif fname.startswith("adr-") and "template" not in fname.lower():
+            result["adrs"] = [ADR(
+                adr_id=doc_id,
+                title=title,
+                status=status,
+                context=body,
+                decision="",
+            )]
+
+        return result
diff --git a/backend/tests/test_scanner_parsers.py b/backend/tests/test_scanner_parsers.py
index fb95340..0fc7a3b 100644
--- a/backend/tests/test_scanner_parsers.py
+++ b/backend/tests/test_scanner_parsers.py
@@ -183,3 +183,119 @@ class TestCsvParserUnknown:
     def test_nonexistent_file_returns_empty(self, csv_parser):
         result = csv_parser.parse(Path("/nonexistent/file.csv"))
         assert result == {}
+
+
+# ── MD Parser Tests ──
+
+from app.modules.scanner.infrastructure.parsers.md_parser import MdParser
+
+
+@pytest.fixture
+def md_parser():
+    return MdParser()
+
+
+class TestMdParserScopeAndGoals:
+    def test_parse_scope_and_goals(self, md_parser):
+        result = md_parser.parse(DESIGN_DIR / "business-architecture" / "01-scope-and-goals.md")
+        assert "design_documents" in result
+        docs = result["design_documents"]
+        assert len(docs) == 1
+        assert docs[0].doc_id == "DOC-BA-001"
+        assert docs[0].title == "范围与目标"
+        assert isinstance(docs[0].owners, list)
+        assert isinstance(docs[0].downstream, list)
+        assert "scope_and_goals" in result
+        sag = result["scope_and_goals"]
+        assert len(sag) == 1
+        assert sag[0].doc_id == "DOC-BA-001"
+
+
+class TestMdParserDomainOverview:
+    def test_parse_domain_overview(self, md_parser):
+        result = md_parser.parse(DESIGN_DIR / "domains" / "design" / "01-domain-overview.md")
+        # domain-overview.md has no frontmatter in this repo, so it produces no DesignDocument
+        # If it has no frontmatter, it returns empty
+        # Check: this file does not have frontmatter
+        content = (DESIGN_DIR / "domains" / "design" / "01-domain-overview.md").read_text()
+        if content.startswith("---"):
+            assert "design_documents" in result
+            assert "domains" in result
+            assert result["domains"][0].domain_name == "design"
+        else:
+            # No frontmatter, so empty result and Domain produced from filename
+            assert result == {} or "domains" in result
+
+
+class TestMdParserSystemContext:
+    def test_parse_system_context(self, md_parser):
+        result = md_parser.parse(DESIGN_DIR / "application-architecture" / "01-system-context.md")
+        assert "design_documents" in result
+        assert "system_context" in result
+        sc = result["system_context"]
+        assert len(sc) == 1
+        assert sc[0].doc_id == "DOC-AA-001"
+        assert sc[0].title == "系统上下文"
+        assert len(sc[0].content) > 0
+
+
+class TestMdParserAdrTemplate:
+    def test_adr_template_no_adr_entity(self, md_parser):
+        result = md_parser.parse(DESIGN_DIR / "adr" / "ADR-000-template.md")
+        # ADR-000-template has no frontmatter, so empty
+        content = (DESIGN_DIR / "adr" / "ADR-000-template.md").read_text()
+        if not content.startswith("---"):
+            assert result == {}
+        else:
+            # If it has frontmatter, should NOT produce ADR (it's a template)
+            assert "adrs" not in result
+
+
+class TestMdParserNoFrontmatter:
+    def test_no_frontmatter_returns_empty(self, md_parser, tmp_path):
+        md = tmp_path / "test.md"
+        md.write_text("# Just a heading\n\nSome content.\n")
+        result = md_parser.parse(md)
+        assert result == {}
+
+    def test_nonexistent_md_returns_empty(self, md_parser):
+        result = md_parser.parse(Path("/nonexistent/file.md"))
+        assert result == {}
+
+
+class TestMdParserSolutionLayering:
+    def test_parse_solution_layering(self, md_parser):
+        result = md_parser.parse(DESIGN_DIR / "application-architecture" / "02b-solution-layering.md")
+        assert "design_documents" in result
+        assert "solution_layer" in result
+        sl = result["solution_layer"]
+        assert len(sl) == 1
+        assert sl[0].doc_id == "DOC-AA-003"
+
+
+class TestMdParserModuleBoundary:
+    def test_parse_module_boundary(self, md_parser):
+        result = md_parser.parse(DESIGN_DIR / "application-architecture" / "07-module-boundary-rules.md")
+        assert "design_documents" in result
+        assert "module_boundary_rule" in result
+
+
+class TestMdParserRuntimeTopology:
+    def test_parse_runtime_topology(self, md_parser):
+        result = md_parser.parse(DESIGN_DIR / "technology-architecture" / "01-runtime-topology.md")
+        assert "design_documents" in result
+        assert "runtime_topology" in result
+
+
+class TestMdParserOperationalBaseline:
+    def test_parse_operational_baseline(self, md_parser):
+        result = md_parser.parse(DESIGN_DIR / "technology-architecture" / "03-operational-baseline.md")
+        assert "design_documents" in result
+        assert "operational_baseline" in result
+
+
+class TestMdParserReleasePlan:
+    def test_parse_release_plan(self, md_parser):
+        result = md_parser.parse(DESIGN_DIR / "technology-architecture" / "04-release-and-rollback.md")
+        assert "design_documents" in result
+        assert "release_plan" in result