diff --git a/Tools/lsp/probe.py b/Tools/lsp/probe.py
index 63165cd..826e4bc 100644
--- a/Tools/lsp/probe.py
+++ b/Tools/lsp/probe.py
@@ -422,6 +422,18 @@ def gate2(exe: str) -> int:
     functions = {(t["line"], t["character"]) for t in sem_tokens if t["type"] == function_type}
     if (0, 4) not in functions or (3, 4) not in functions:
         raise AssertionError(f"semantic tokens lost after a lexer error: {sem_tokens}")
+    # Fixing the literal must clear the overflow diagnostic (lexer fail-fast state is global and
+    # must be reset for the next parse, otherwise the stale error sticks to every later edit).
+    fixed_overflow = overflow.replace("1024000000000000000000", "1")
+    client.notify(
+        "textDocument/didChange",
+        {"textDocument": {"uri": uri, "version": 4},
+         "contentChanges": [{"text": fixed_overflow}]},
+    )
+    publish = client.wait_notification("textDocument/publishDiagnostics")
+    diagnostics = publish.get("params", {}).get("diagnostics")
+    if not isinstance(diagnostics, list) or len(diagnostics) != 0:
+        raise AssertionError(f"fixed overflow literal still reports diagnostics: {publish}")
     client.notify("textDocument/didClose", {"textDocument": {"uri": uri}})
     client.wait_notification("textDocument/publishDiagnostics")
 
@@ -455,6 +467,17 @@ def gate2(exe: str) -> int:
     items = pulled.get("items", []) if isinstance(pulled, dict) else []
     if len(items) != 1:
         raise AssertionError(f"pull diagnostics returned {len(items)} items: {pulled}")
+    pull_client.notify(
+        "textDocument/didChange",
+        {"textDocument": {"uri": uri, "version": 5},
+         "contentChanges": [{"text": fixed_overflow}]},
+    )
+    pulled = pull_client.request(
+        "textDocument/diagnostic", {"textDocument": {"uri": uri}}, timeout=60.0
+    ).get("result")
+    items = pulled.get("items", []) if isinstance(pulled, dict) else []
+    if len(items) != 0:
+        raise AssertionError(f"pull diagnostics kept the stale overflow: {pulled}")
     pull_client.request("shutdown")
     pull_client.close()