diff --git a/scripts/repo-scan.py b/scripts/repo-scan.py
index 6146041..d8bc5f0 100644
--- a/scripts/repo-scan.py
+++ b/scripts/repo-scan.py
@@ -41,6 +41,16 @@ LIST_ITEM_RE = re.compile(r"^\s*(\d+\.|[-*+])\s+(.*)")
 DEFER_REF_RE = re.compile(r"ADR-(\d{3})\D{0,40}?deferred\D{0,12}?(\d+)", re.I)
 RESOLVE_WORD_RE = re.compile(r"\b(?:resolv\w*|decid\w*|address\w*|complet\w*|done)\b", re.I)
 
+# ADR-structure check (ADR-023): numbered ADRs must carry the four mandatory
+# sections and a parseable Status line. Presence only — section ORDER is a
+# template-demonstrated convention, not machine-enforced.
+ADR_FILE_RE = re.compile(r"^\d{3}-.*\.md$")
+ADR_REQUIRED_SECTIONS = ("Status", "Context", "Decision", "Consequences")
+ADR_STATUS_LINE_RE = re.compile(
+    r"^(Accepted \(\d{4}-\d{2}-\d{2}\)"
+    r"|Superseded by ADR-\d{3}"
+    r"|Deprecated \(\d{4}-\d{2}-\d{2}\))")
+
 
 def _is_defer_heading(text):
     t = text.strip().lower()
@@ -95,6 +105,41 @@ def deferred_findings(adr_files, defer_refs):
     return out
 
 
+def adr_structure_findings(adr_files):
+    """adr_files: {rel_path: [lines]} for docs/decisions/*.md.
+    Flags numbered ADRs (NNN-*.md) missing a mandatory section or whose Status
+    section has no parseable lifecycle line. Non-numbered files (e.g.
+    adr-template.md) are skipped. Section order is NOT checked (ADR-023)."""
+    out = []
+    for rpath, lines in sorted(adr_files.items()):
+        if not ADR_FILE_RE.match(os.path.basename(rpath)):
+            continue
+        headings = {}
+        for i, line in enumerate(lines):
+            m = re.match(r"^##\s+(\w+)", line)
+            if m:
+                headings.setdefault(m.group(1), i)
+        missing = [s for s in ADR_REQUIRED_SECTIONS if s not in headings]
+        if missing:
+            out.append({"check": "adr-structure", "severity": "medium",
+                        "path": rpath, "line": 1,
+                        "detail": f"missing mandatory section(s): {', '.join(missing)}"})
+        if "Status" in headings:
+            body = []
+            for line in lines[headings["Status"] + 1:]:
+                if line.startswith("## "):
+                    break
+                body.append(line)
+            status_text = next((ln.strip() for ln in body if ln.strip()), "")
+            if not ADR_STATUS_LINE_RE.match(status_text):
+                out.append({"check": "adr-structure", "severity": "medium",
+                            "path": rpath, "line": headings["Status"] + 1,
+                            "detail": "Status not parseable (want 'Accepted (YYYY-MM-DD)', "
+                                      "'Superseded by ADR-NNN', or 'Deprecated (YYYY-MM-DD)'); "
+                                      f"got: {status_text[:60]!r}"})
+    return out
+
+
 def walk_files():
     for dirpath, dirnames, filenames in os.walk(ROOT):
         dirnames[:] = [d for d in dirnames if d not in PRUNE]
@@ -213,6 +258,7 @@ def scan():
                     findings.append({"check": "broken-path-ref", "severity": "medium", "path": rpath,
                                      "line": i, "detail": f"references '{ref}' which does not exist"})
     findings.extend(deferred_findings(adr_files, defer_refs))
+    findings.extend(adr_structure_findings(adr_files))
     return findings
 
 
diff --git a/tests/test_repo_scan.py b/tests/test_repo_scan.py
new file mode 100644
index 0000000..e8a0542
--- /dev/null
+++ b/tests/test_repo_scan.py
@@ -0,0 +1,52 @@
+import importlib.util
+import pathlib
+
+_PATH = pathlib.Path(__file__).resolve().parent.parent / "scripts" / "repo-scan.py"
+_spec = importlib.util.spec_from_file_location("repo_scan", _PATH)
+rs = importlib.util.module_from_spec(_spec)
+_spec.loader.exec_module(rs)
+
+GOOD = [
+    "# ADR-099 — Example\n", "\n",
+    "## Status\n", "\n", "Accepted (2026-06-10)\n", "\n",
+    "## Context\n", "\n", "Why.\n", "\n",
+    "## Decision\n", "\n", "What.\n", "\n",
+    "## Consequences\n", "\n", "So what.\n",
+]
+
+
+def _checks(findings):
+    return [f for f in findings if f["check"] == "adr-structure"]
+
+
+def test_good_adr_has_no_findings():
+    out = rs.adr_structure_findings({"docs/decisions/099-example.md": GOOD})
+    assert _checks(out) == []
+
+
+def test_missing_mandatory_section_is_flagged():
+    lines = [ln for ln in GOOD if not ln.startswith("## Consequences")]
+    out = _checks(rs.adr_structure_findings({"docs/decisions/099-example.md": lines}))
+    assert len(out) == 1
+    assert "Consequences" in out[0]["detail"]
+
+
+def test_unparseable_status_is_flagged():
+    lines = [("Designed, not built.\n" if ln == "Accepted (2026-06-10)\n" else ln)
+             for ln in GOOD]
+    out = _checks(rs.adr_structure_findings({"docs/decisions/099-example.md": lines}))
+    assert len(out) == 1
+    assert "Status not parseable" in out[0]["detail"]
+
+
+def test_superseded_status_is_accepted():
+    lines = [("Superseded by ADR-100 (2026-06-11)\n" if ln == "Accepted (2026-06-10)\n"
+              else ln) for ln in GOOD]
+    out = _checks(rs.adr_structure_findings({"docs/decisions/099-example.md": lines}))
+    assert out == []
+
+
+def test_non_numbered_file_is_skipped():
+    bare = ["# ADR template\n", "\n", "## Status\n", "\n", "<!-- hint -->\n"]
+    out = _checks(rs.adr_structure_findings({"docs/decisions/adr-template.md": bare}))
+    assert out == []