diff --git a/mcp-server/tests/test_sync_verify_gate.py b/mcp-server/tests/test_sync_verify_gate.py
new file mode 100644
index 0000000..cca3e1b
--- /dev/null
+++ b/mcp-server/tests/test_sync_verify_gate.py
@@ -0,0 +1,48 @@
+"""FU-8a / GAP-21: sync --verify drift-gate logic (offline)."""
+from __future__ import annotations
+
+import importlib.util
+from pathlib import Path
+
+_SCRIPT = Path(__file__).resolve().parents[2] / "scripts" / "sync_agents_across_companies.py"
+_spec = importlib.util.spec_from_file_location("sync_agents", _SCRIPT)
+sync = importlib.util.module_from_spec(_spec)
+_spec.loader.exec_module(sync)
+
+
+def _agent(name, adapter="claude_code", cfg=None):
+    return {"id": f"id-{name}", "name": name, "adapter_type": adapter,
+            "adapter_config": cfg or {"model": "x"}, "runtime_config": {}, "metadata": {},
+            "budget_monthly_cents": 0, "icon": "", "title": "", "role": "", "agent_api_keys": []}
+
+
+def test_verify_exit_code_clean_is_zero():
+    assert sync._verify_exit_code(plan=[], mismatches=[], missing=[]) == 0
+
+
+def test_verify_exit_code_drift_is_nonzero():
+    assert sync._verify_exit_code(plan=[("m", "mi", {"x": 1})], mismatches=[], missing=[]) == 1
+
+
+def test_verify_exit_code_adapter_mismatch_is_nonzero():
+    assert sync._verify_exit_code(plan=[], mismatches=["עוזר משפטי"], missing=[]) == 1
+
+
+def test_verify_exit_code_missing_is_nonzero():
+    assert sync._verify_exit_code(plan=[], mismatches=[], missing=["סוכן"]) == 1
+
+
+def test_build_drift_report_flags_adapter_mismatch():
+    master = [_agent("A", adapter="claude_code")]
+    mirror_by_name = {"A": _agent("A", adapter="deepseek_local")}
+    rep = sync.build_drift_report(master, mirror_by_name, mirror_skills=set(), only=None)
+    assert "A" in rep["mismatches"]
+    assert rep["plan"] == []
+
+
+def test_build_drift_report_flags_missing_and_plan():
+    master = [_agent("A"), _agent("B")]
+    mirror_by_name = {"B": _agent("B", cfg={"model": "different"})}
+    rep = sync.build_drift_report(master, mirror_by_name, mirror_skills=set(), only=None)
+    assert "A" in rep["missing"]
+    assert any(p[0]["name"] == "B" for p in rep["plan"])
diff --git a/scripts/sync_agents_across_companies.py b/scripts/sync_agents_across_companies.py
index 5f00c0f..6273bcf 100644
--- a/scripts/sync_agents_across_companies.py
+++ b/scripts/sync_agents_across_companies.py
@@ -345,6 +345,33 @@ async def check_instructions(agents: list[dict]) -> bool:
     return all_ok
 
 
+def build_drift_report(master_agents, mirror_by_name, mirror_skills, only=None) -> dict:
+    """Pure drift computation (no DB, no printing). Returns:
+    {"plan": [(master, mirror, diff), ...], "mismatches": [name, ...], "missing": [name, ...]}.
+    adapter_type mismatch and missing-in-mirror are recorded as drift, not skipped silently.
+    """
+    plan, mismatches, missing = [], [], []
+    for m in master_agents:
+        if only and m["name"] != only:
+            continue
+        mirror = mirror_by_name.get(m["name"])
+        if not mirror:
+            missing.append(m["name"])
+            continue
+        if m["adapter_type"] != mirror["adapter_type"]:
+            mismatches.append(m["name"])
+            continue
+        diff = compute_diff(m, mirror, mirror_skills)
+        if diff:
+            plan.append((m, mirror, diff))
+    return {"plan": plan, "mismatches": mismatches, "missing": missing}
+
+
+def _verify_exit_code(plan, mismatches, missing) -> int:
+    """0 iff fully in sync; 1 if any drift (needs-sync / adapter mismatch / missing-in-mirror)."""
+    return 1 if (plan or mismatches or missing) else 0
+
+
 async def main() -> None:
     p = argparse.ArgumentParser()
     g = p.add_mutually_exclusive_group(required=True)
@@ -376,26 +403,23 @@ async def main() -> None:
     print(f"=== Mirror has {len(mirror_skills)} local skills available ===\n")
 
     print(f"=== Drift report ===")
-    plan: list[tuple[dict, dict, dict]] = []  # (master, mirror, diff)
-    for m in master_agents:
-        if args.only and m["name"] != args.only:
-            continue
-        mirror = mirror_by_name.get(m["name"])
-        if not mirror:
-            print(f"  ⚠ {m['name']:14s} — NOT FOUND in mirror (skipping; we never auto-create)")
-            continue
-        if m["adapter_type"] != mirror["adapter_type"]:
-            print(f"  ⚠ {m['name']:14s} — adapter_type mismatch ({m['adapter_type']} vs {mirror['adapter_type']}) — SKIPPING")
-            continue
-        diff = compute_diff(m, mirror, mirror_skills)
-        print_diff(m["name"], diff, m["id"], mirror["id"])
-        if diff:
-            plan.append((m, mirror, diff))
+    report = build_drift_report(master_agents, mirror_by_name, mirror_skills, only=args.only)
+    plan = report["plan"]
+    for name in report["missing"]:
+        print(f"  ⚠ {name:14s} — NOT FOUND in mirror (we never auto-create) — DRIFT")
+    for name in report["mismatches"]:
+        m = next(a for a in master_agents if a["name"] == name)
+        mi = mirror_by_name[name]
+        print(f"  ❌ {name:14s} — adapter_type mismatch ({m['adapter_type']} vs {mi['adapter_type']}) "
+              f"— DRIFT (apply skips it; fix manually in both companies)")
+    for master, mirror, diff in plan:
+        print_diff(master["name"], diff, master["id"], mirror["id"])
 
     if args.verify:
-        print(f"\n(verify mode — exiting without changes)")
-        print(f"\nSummary: {len(plan)} agent(s) need sync, {len(master_agents) - len(plan)} in sync")
-        return
+        code = _verify_exit_code(plan, report["mismatches"], report["missing"])
+        print(f"\nSummary: {len(plan)} need sync, {len(report['mismatches'])} adapter-mismatch, "
+              f"{len(report['missing'])} missing-in-mirror → {'DRIFT' if code else 'IN SYNC'}")
+        sys.exit(code)
 
     if not plan:
         print(f"\n✓ All agents in sync — nothing to do.")