fix(web): history tab copy — every chat saves automatically, there is no Save button

meta description -> locked (A3) auto-save string (history.html L6).
page-sub -> locked (A3) string, the <strong>Save</strong> emphasis retired with the button (L106-109).
empty row -> locked (A3) string; colspan=6, hidden, and row id untouched (L163).
h1, the anonymous gate section, and history.js are byte-identical — state language verified accurate.

tests/unit/test_history_copy.py

@@ -0,0 +1,79 @@
+"""Unit: phase-66 text pins — the History tab describes the auto-save
+model, not the retired Save button.
+
+House pattern (``test_stale_ui_copy.py``): read ``frontend/history.html``
+as text and assert substrings — no browser. The browser-visible layer is
+gated by the dedicated story suite (``tests/e2e/test_history_copy.py``);
+these pins catch a silent regression in the template without it.
+
+Locked decision (owner-locked A3, 2026-09-01): every conversation saves
+itself automatically — there is NO Save button (retired phase 55, owner-
+locked A2, pinned by ``test_save_share_ux.py::test_anonymous_auto_save``),
+so no user-visible History-tab string may name one.
+"""
+from __future__ import annotations
+
+import re
+from pathlib import Path
+
+FRONTEND = Path(__file__).resolve().parents[2] / "frontend"
+
+# --- the locked auto-save copy (owner-locked A3) -----------------------
+
+META = "Saved chats — every conversation is saved automatically, one click back."
+PAGE_SUB = (
+    "Every conversation is saved automatically — newest activity first. "
+    "Click a title to return to that chat."
+)
+EMPTY_ROW = "No saved chats yet — start a conversation and it will be saved automatically."
+
+# --- the retired manual-save copy (must be nowhere) --------------------
+
+OLD_META = "every conversation you saved"
+OLD_PAGE_SUB = "you pressed <strong>Save</strong>"
+OLD_EMPTY_ROW = "press <strong>Save</strong> in the chat"
+
+# --- state-language survivors (must STAY — "saved" is a state, not a
+#     button; their absence would prove over-deletion) ------------------
+
+STATE_STRINGS = (
+    "<h1>Saved chats</h1>",
+    "Sign in to view your saved chats",
+    "Saved conversations are admin-only",
+)
+
+
+def _text() -> str:
+    return (FRONTEND / "history.html").read_text(encoding="utf-8")
+
+
+def _norm(text: str) -> str:
+    """Collapse whitespace runs — the templates wrap long lines, so the
+    locked copy is pinned against the normalized text."""
+    return re.sub(r"\s+", " ", text).strip()
+
+
+def test_manual_save_copy_is_gone() -> None:
+    """history.html: the three retired manual-save strings are GONE —
+    the copy no longer tells the visitor to press a Save button."""
+    html = _text()
+    for frag in (OLD_META, OLD_PAGE_SUB, OLD_EMPTY_ROW):
+        assert frag not in html, f"retired manual-save copy still present: {frag!r}"
+
+
+def test_locked_auto_save_copy_present_exactly_once() -> None:
+    """The three locked (A3) auto-save strings, each exactly once in
+    history.html (a second copy could drift out of sync)."""
+    html = _norm(_text())
+    assert html.count(META) == 1, "the locked meta description"
+    assert html.count(PAGE_SUB) == 1, "the locked page-sub"
+    assert html.count(EMPTY_ROW) == 1, "the locked empty-row string"
+
+
+def test_state_language_survivors_are_untouched() -> None:
+    """Proof of NO over-deletion: the strings where "saved" is a state —
+    the <h1>, the anonymous gate title, and the gate sub — stay exactly
+    as phase 50 wrote them."""
+    html = _text()
+    for frag in STATE_STRINGS:
+        assert frag in html, f"state-language survivor deleted: {frag!r}"