diff --git a/backend-compliance/compliance/api/agent_check/_b16_wiring.py b/backend-compliance/compliance/api/agent_check/_b16_wiring.py
new file mode 100644
index 00000000..b11ef600
--- /dev/null
+++ b/backend-compliance/compliance/api/agent_check/_b16_wiring.py
@@ -0,0 +1,66 @@
+"""B16 wiring — Footer-Label-vs-URL-Slug-Drift-Detector.
+
+Hängt sich an `state["extra_findings"]` an und rendert einen V2-Block
+(`url_slug_drift_html`).
+"""
+
+from __future__ import annotations
+
+import html
+import logging
+
+from compliance.services.url_slug_drift_check import check_url_slug_drift
+
+logger = logging.getLogger(__name__)
+
+
+def run_b16(state: dict) -> None:
+    new = check_url_slug_drift(state)
+    if not new:
+        return
+    extras = state.get("extra_findings") or []
+    extras.extend(new)
+    state["extra_findings"] = extras
+    state["url_slug_drift_html"] = _render(new)
+    logger.info("B16 url-slug-drift: %d finding(s)", len(new))
+
+
+def _render(findings: list[dict]) -> str:
+    cards = []
+    for f in findings:
+        sev = (f.get("severity") or "").upper()
+        color = "#64748b" if sev == "LOW" else "#f59e0b"
+        alts = f.get("alt_slugs_404") or []
+        alts_html = ""
+        if alts:
+            alts_html = (
+                "<div style='font-size:12px;color:#475569;margin-top:6px;'>"
+                f"<em>404-Slugs: {html.escape(', '.join(alts))}</em></div>"
+            )
+        cards.append(
+            f"<div style='margin:12px 0;padding:14px;background:#fff;"
+            f"border-left:3px solid {color};border-radius:4px;'>"
+            f"<div style='font-weight:600;color:{color};font-size:14px;'>"
+            f"{sev} · {html.escape(f.get('check_id') or '')}</div>"
+            f"<div style='font-size:14px;margin-top:4px;'>"
+            f"<strong>{html.escape(f.get('title') or '')}</strong></div>"
+            f"<div style='font-size:12px;color:#64748b;margin-top:2px;'>"
+            f"{html.escape(f.get('norm') or '')}</div>"
+            f"{alts_html}"
+            f"<div style='font-size:12px;color:#475569;margin-top:6px;'>"
+            f"<em>{html.escape(f.get('evidence') or '')}</em></div>"
+            f"<div style='font-size:13px;margin-top:8px;background:#dcfce7;"
+            f"padding:8px 10px;border-radius:4px;'>"
+            f"<strong>→ Empfehlung:</strong> "
+            f"{html.escape(f.get('action') or '')}</div>"
+            "</div>"
+        )
+    return (
+        "<div style='margin:24px 0;padding:16px;border-left:4px solid #64748b;"
+        "background:#f8fafc;border-radius:4px;'>"
+        "<h2 style='margin:0 0 8px;color:#475569;font-size:16px;'>"
+        "🔗 Standard-Slug-Brüche (SEO / Bookmarks)"
+        "</h2>"
+        + "".join(cards) +
+        "</div>"
+    )
diff --git a/backend-compliance/compliance/api/agent_check/_orchestrator.py b/backend-compliance/compliance/api/agent_check/_orchestrator.py
index de219e12..235492d2 100644
--- a/backend-compliance/compliance/api/agent_check/_orchestrator.py
+++ b/backend-compliance/compliance/api/agent_check/_orchestrator.py
@@ -26,6 +26,7 @@ from ._b12_wiring import run_b12
 from ._b13_wiring import run_b13
 from ._b14_wiring import run_b14
 from ._b15_wiring import run_b15
+from ._b16_wiring import run_b16
 from ._constants import _compliance_check_jobs
 from ._phase_a_resolve import run_phase_a
 from ._phase_b_profile_check import run_phase_b
@@ -76,6 +77,7 @@ async def run_compliance_check(check_id: str, req) -> None:
         run_b13(state)  # Widerrufsbelehrung-Reachability (B2C-Pflicht)
         run_b14(state)  # Widersprüchliche Speicherdauer im selben Doc
         run_b15(state)  # AI-Act Rechtsgrundlage (LLM-Vendor auf lit. f)
+        run_b16(state)  # Footer-Label-vs-URL-Slug-Drift
         # Phase D-3 top/mid/bot: Step 5 HTML blocks
         await run_phase_d3_top(state)
         await run_phase_d3_mid(state)
diff --git a/backend-compliance/compliance/services/mail_render_v2/_compose.py b/backend-compliance/compliance/services/mail_render_v2/_compose.py
index 083ae470..ba7baafb 100644
--- a/backend-compliance/compliance/services/mail_render_v2/_compose.py
+++ b/backend-compliance/compliance/services/mail_render_v2/_compose.py
@@ -54,6 +54,8 @@ def compose_v2(state: dict) -> str:
         state.get("retention_conflict_html", ""),
         # B15 AI-Act Rechtsgrundlage (LLM-Vendor auf lit. f)
         state.get("ai_legal_basis_html", ""),
+        # B16 Footer-Label-vs-URL-Slug-Drift (SEO / Bookmarks)
+        state.get("url_slug_drift_html", ""),
         # Browser-Matrix (Stage 1.c)
         state.get("browser_matrix_html", ""),
         # All legacy build_*_html() wrapped in V2 sections — preserves
diff --git a/backend-compliance/compliance/services/url_slug_drift_check.py b/backend-compliance/compliance/services/url_slug_drift_check.py
new file mode 100644
index 00000000..1435e5a9
--- /dev/null
+++ b/backend-compliance/compliance/services/url_slug_drift_check.py
@@ -0,0 +1,206 @@
+"""B16 — Footer-Label-vs-URL-Slug-Drift-Detector.
+
+Erkennt: gängige Footer-Labels (z.B. "Cookie-Richtlinie", "AGB",
+"Datenschutzerklärung") existieren als Bookmark-/SEO-Erwartung,
+aber auf der Site antwortet der entsprechende Standard-Slug mit 404.
+Real wird das Doc unter einem abweichenden Slug ausgeliefert.
+
+GT-Anker: Elli URL-STRUCTURE-001:
+  Footer-Label "Cookie-Richtlinie" → /cookie-richtlinie 404
+  Footer-Label "AGB"               → /agb 404
+  Real: /de/cookies, /de/nutzungsbedingungen.
+
+Heuristik:
+  1. Aus den discovered URLs den Base-Host extrahieren.
+  2. Pro doc_type eine kleine Liste kanonischer Standard-Slugs prüfen
+     (HEAD oder GET), je 2 s Timeout.
+  3. Wenn discovered Slug bekannt ist, ABER mindestens ein
+     gleichwertiger Standard-Slug 404 ergibt → LOW Finding pro alt-Slug.
+
+Severity: LOW (SEO/Bookmark-Bruch, kein juristisches Hardfail).
+"""
+
+from __future__ import annotations
+
+import logging
+import os
+from concurrent.futures import ThreadPoolExecutor
+from urllib.parse import urlparse
+
+import httpx
+
+logger = logging.getLogger(__name__)
+
+
+# Kanonische DE/EN Standard-Slugs pro doc_type (ohne führenden /).
+# Reihenfolge: erst der häufigste deutsche, dann Synonyme, dann EN.
+_CANONICAL_SLUGS: dict[str, tuple[str, ...]] = {
+    "dse": (
+        "datenschutz", "datenschutzerklaerung", "datenschutzerklärung",
+        "privacy", "privacy-policy",
+    ),
+    "impressum": (
+        "impressum", "imprint", "legal-notice",
+    ),
+    "cookie": (
+        "cookie-richtlinie", "cookies", "cookie-policy",
+    ),
+    "agb": (
+        "agb", "allgemeine-geschaeftsbedingungen",
+        "geschaeftsbedingungen", "terms-and-conditions",
+    ),
+    "nutzungsbedingungen": (
+        "nutzungsbedingungen", "terms-of-use", "terms-of-service",
+    ),
+    "widerruf": (
+        "widerrufsbelehrung", "widerruf", "cancellation",
+    ),
+}
+
+
+# Konfigurations-Schalter (default: AN; lässt sich pro Run abschalten).
+_DISABLED = os.environ.get("URL_SLUG_PROBE_DISABLED", "").lower() in (
+    "1", "true", "yes", "on",
+)
+
+
+def _strip_path_slug(url: str) -> str:
+    """Return the LAST path-segment of a URL (without trailing /)."""
+    if not url:
+        return ""
+    try:
+        p = urlparse(url)
+        path = (p.path or "").strip("/")
+        if not path:
+            return ""
+        return path.split("/")[-1].lower()
+    except Exception:
+        return ""
+
+
+def _origin_and_prefix(url: str) -> tuple[str, str]:
+    """Return (origin, language-prefix-or-empty) so we can rebuild
+    alternative URLs at the same scope as the discovered one.
+
+    Example: 'https://www.elli.eco/de/cookies' → ('https://www.elli.eco', '/de')
+    """
+    try:
+        p = urlparse(url)
+        origin = f"{p.scheme}://{p.netloc}"
+        path = p.path or "/"
+        parts = [s for s in path.split("/") if s]
+        # Heuristik: ein 2-3 Zeichen-Pfad-Segment ganz vorn wird als
+        # Sprach-Prefix interpretiert (de, en, fr, de-de, en-us).
+        if parts and (len(parts[0]) == 2 or len(parts[0]) == 5):
+            return origin, f"/{parts[0]}"
+        return origin, ""
+    except Exception:
+        return "", ""
+
+
+def _head_status(url: str, timeout_s: float = 2.0) -> int:
+    """Return HTTP status code (0 on network error)."""
+    try:
+        with httpx.Client(timeout=timeout_s, follow_redirects=False) as c:
+            r = c.head(url)
+            # Some servers reject HEAD with 405 — fall back to GET.
+            if r.status_code == 405:
+                r = c.get(url)
+            return r.status_code
+    except Exception:
+        return 0
+
+
+def check_url_slug_drift(state: dict) -> list[dict]:
+    """Probe canonical alternative slugs per discovered doc; emit a LOW
+    finding per slug that 404s while the doc is reachable under a
+    different slug."""
+    if _DISABLED:
+        return []
+    doc_entries = state.get("doc_entries") or []
+    # Build {doc_type: (discovered_url, discovered_slug)} for
+    # auto-discovered docs with non-empty text.
+    discovered: dict[str, tuple[str, str]] = {}
+    for e in doc_entries:
+        dt = (e.get("doc_type") or "").lower()
+        if dt not in _CANONICAL_SLUGS:
+            continue
+        url = (e.get("url") or "").strip()
+        text_len = len((e.get("text") or "").strip())
+        if not url or text_len < 400:
+            continue
+        slug = _strip_path_slug(url)
+        if not slug:
+            continue
+        discovered[dt] = (url, slug)
+
+    if not discovered:
+        return []
+
+    # Build probe-plan: for each doc_type, probe the canonical slugs
+    # OTHER than the one that's already discovered.
+    probes: list[tuple[str, str, str]] = []  # (doc_type, alt_slug, url)
+    for dt, (url, slug) in discovered.items():
+        origin, prefix = _origin_and_prefix(url)
+        if not origin:
+            continue
+        for alt in _CANONICAL_SLUGS[dt]:
+            if alt.lower() == slug:
+                continue
+            probes.append((dt, alt, f"{origin}{prefix}/{alt}"))
+
+    # Cap to keep network noise bounded.
+    probes = probes[:18]
+    if not probes:
+        return []
+
+    def _do_probe(item: tuple[str, str, str]) -> tuple[str, str, str, int]:
+        dt, alt, u = item
+        return dt, alt, u, _head_status(u)
+
+    results: list[tuple[str, str, str, int]] = []
+    with ThreadPoolExecutor(max_workers=6) as ex:
+        results = list(ex.map(_do_probe, probes))
+
+    findings: list[dict] = []
+    # Group by doc_type so we can emit ONE finding per doc with the
+    # list of 404-alts.
+    per_dt: dict[str, list[tuple[str, str]]] = {}
+    for dt, alt, u, status in results:
+        if status == 404 or status == 410:
+            per_dt.setdefault(dt, []).append((alt, u))
+
+    for dt, alts in per_dt.items():
+        if not alts:
+            continue
+        discovered_url, discovered_slug = discovered[dt]
+        broken_urls = ", ".join(u for _, u in alts[:3])
+        broken_slugs = ", ".join(s for s, _ in alts[:3])
+        findings.append({
+            "check_id": "URL-SLUG-DRIFT-001",
+            "severity": "LOW",
+            "severity_reason": "seo_bookmark_break",
+            "doc_type": dt,
+            "title": (
+                f"Externe Bookmarks / SEO-Erwartung für {dt} brechen "
+                f"({len(alts)} Standard-Slug(s) 404)"
+            ),
+            "norm": (
+                "Kein juristischer Pflichttatbestand — Best-Practice "
+                "(SEO, externe Verlinkungen, Footer-Label-Konsistenz)"
+            ),
+            "evidence": (
+                f"Doc ist erreichbar unter '{discovered_url}'. "
+                f"Standard-Slug(s) {broken_slugs} liefern 404/410 "
+                f"({broken_urls})."
+            ),
+            "action": (
+                f"Redirects einrichten von {broken_slugs} nach "
+                f"'{discovered_url}' — damit externe Bookmarks, "
+                "alte Footer-Labels und Google-Treffer nicht brechen."
+            ),
+            "alt_slugs_404": [s for s, _ in alts],
+        })
+    if findings:
+        logger.info("B16 url-slug-drift: %d finding(s)", len(findings))
+    return findings
diff --git a/backend-compliance/tests/test_url_slug_drift_check.py b/backend-compliance/tests/test_url_slug_drift_check.py
new file mode 100644
index 00000000..55d4d4af
--- /dev/null
+++ b/backend-compliance/tests/test_url_slug_drift_check.py
@@ -0,0 +1,139 @@
+"""Tests for B16 URL-Slug-Drift-Detector (GT URL-STRUCTURE-001)."""
+
+from unittest.mock import patch
+
+from compliance.services.url_slug_drift_check import (
+    _origin_and_prefix,
+    _strip_path_slug,
+    check_url_slug_drift,
+)
+
+
+class TestStripPathSlug:
+    def test_simple(self):
+        assert _strip_path_slug("https://x.de/cookies") == "cookies"
+
+    def test_with_lang_prefix(self):
+        assert _strip_path_slug("https://x.de/de/cookies") == "cookies"
+
+    def test_trailing_slash(self):
+        assert _strip_path_slug("https://x.de/cookies/") == "cookies"
+
+    def test_empty(self):
+        assert _strip_path_slug("") == ""
+
+
+class TestOriginAndPrefix:
+    def test_lang_prefix(self):
+        assert _origin_and_prefix("https://www.elli.eco/de/cookies") == (
+            "https://www.elli.eco", "/de",
+        )
+
+    def test_no_lang_prefix(self):
+        assert _origin_and_prefix("https://x.de/cookies") == (
+            "https://x.de", "",
+        )
+
+    def test_locale_prefix(self):
+        assert _origin_and_prefix("https://x.de/de-de/cookies") == (
+            "https://x.de", "/de-de",
+        )
+
+
+class TestCheckURLSlugDrift:
+    def test_no_docs_no_findings(self):
+        assert check_url_slug_drift({"doc_entries": []}) == []
+
+    def test_disabled_via_env_no_findings(self, monkeypatch):
+        monkeypatch.setenv("URL_SLUG_PROBE_DISABLED", "1")
+        # Reload module-level _DISABLED flag
+        import importlib
+
+        from compliance.services import url_slug_drift_check
+        importlib.reload(url_slug_drift_check)
+        result = url_slug_drift_check.check_url_slug_drift({
+            "doc_entries": [{
+                "doc_type": "cookie",
+                "url": "https://x.de/de/cookies",
+                "text": "x" * 500,
+            }]
+        })
+        assert result == []
+        # Restore
+        monkeypatch.delenv("URL_SLUG_PROBE_DISABLED")
+        importlib.reload(url_slug_drift_check)
+
+    def test_all_alternatives_200_no_finding(self):
+        with patch(
+            "compliance.services.url_slug_drift_check._head_status",
+            return_value=200,
+        ):
+            result = check_url_slug_drift({
+                "doc_entries": [{
+                    "doc_type": "cookie",
+                    "url": "https://x.de/de/cookies",
+                    "text": "x" * 500,
+                }]
+            })
+        assert result == []
+
+    def test_alternative_404_emits_finding(self):
+        with patch(
+            "compliance.services.url_slug_drift_check._head_status",
+            return_value=404,
+        ):
+            result = check_url_slug_drift({
+                "doc_entries": [{
+                    "doc_type": "cookie",
+                    "url": "https://x.de/de/cookies",
+                    "text": "x" * 500,
+                }]
+            })
+        assert len(result) == 1
+        f = result[0]
+        assert f["check_id"] == "URL-SLUG-DRIFT-001"
+        assert f["severity"] == "LOW"
+        assert f["doc_type"] == "cookie"
+        assert "cookie-richtlinie" in f["alt_slugs_404"]
+
+    def test_short_text_skipped(self):
+        # text < 400 chars → not counted as reachable doc
+        with patch(
+            "compliance.services.url_slug_drift_check._head_status",
+            return_value=404,
+        ):
+            result = check_url_slug_drift({
+                "doc_entries": [{
+                    "doc_type": "cookie",
+                    "url": "https://x.de/de/cookies",
+                    "text": "x" * 50,
+                }]
+            })
+        assert result == []
+
+    def test_elli_pattern_cookie_and_agb_both_emit(self):
+        # Simulate Elli: cookie under /de/cookies, but cookie-richtlinie 404.
+        # agb-doc resolves at /de/nutzungsbedingungen with /agb 404.
+        # Note: nutzungsbedingungen is its own doc_type — Elli's "AGB"
+        # label thus has no canonical doc on the site.
+        state = {
+            "doc_entries": [
+                {"doc_type": "cookie",
+                 "url": "https://x.de/de/cookies",
+                 "text": "x" * 500},
+                {"doc_type": "nutzungsbedingungen",
+                 "url": "https://x.de/de/nutzungsbedingungen",
+                 "text": "x" * 500},
+            ]
+        }
+        with patch(
+            "compliance.services.url_slug_drift_check._head_status",
+            return_value=404,
+        ):
+            result = check_url_slug_drift(state)
+        # cookie has 2 canonical alts (cookie-richtlinie, cookie-policy);
+        # nutzungsbedingungen has 2 alts (terms-of-use, terms-of-service).
+        # Both should emit findings since all alts return 404.
+        doc_types = {f["doc_type"] for f in result}
+        assert "cookie" in doc_types
+        assert "nutzungsbedingungen" in doc_types