test: cover render_summary and The Brief's zone dispatcher

render_summary is the branch's flagship renderer -- drift_summary's
renderer, the sole caller of render_tone_strip, and the only place the
spec's two anti-duplication rules become observable -- and had no
executable test at all.

Two tests in the established spy mould: six eligible deltas in must
produce exactly three cards plus the pointer at the full view, and a
tone-only brief must produce the trajectory sparkline alongside the
rl_summary_none empty state (Ruling A-8's path, previously pinned only
at the order level).

Also pins render()'s dispatcher: inverting `if key in zone_3: continue`
would ship commodity blocks above the fold and differentiated ones
inside a collapsed expander -- the precise inversion this sub-project
exists to fix -- with a green suite. All three tests were confirmed to
fail against a deliberately mutated implementation.

Co-Authored-By: Claude Opus 5 (1M context) <noreply@anthropic.com>

tests/test_brief_order.py

@@ -317,3 +317,129 @@ def test_ask_cta_closes_the_sourced_facts_zone():
     from dashboard.verdict import ZONE_2
 
     assert ZONE_2[-1] == "ask_cta"
+
+
+# ── render_summary: the flagship renderer ───────────────────────────────────
+#
+# The Brief's promoted drift panel. It is the renderer for drift_summary, the
+# SOLE caller of render_tone_strip, and the only place the spec's two
+# anti-duplication rules ("at most three cards", "always point at the full
+# view") become observable.
+
+_TONE_METRIC = (
+    "hedge-word rate 27→13→15→55 per 10k words over FY2025→Q32026 "
+    "(rising 3 quarters) → more cautious"
+)
+
+
+def _tone_delta(term: str = "hedging language") -> dict:
+    delta = _delta("tone_trend", term, "HIGH")
+    delta["computed_metric"] = _TONE_METRIC
+    delta["source"] = "transcript"
+    return delta
+
+
+def test_render_summary_shows_at_most_three_cards_and_points_at_the_full_view(
+    monkeypatch,
+):
+    """Both anti-duplication rules at the render level: The Brief promotes
+    only the top three wording changes, and always tells the reader where the
+    other three live. Nothing else covers either rule at any level."""
+    import dashboard.redline_view as mod
+    from dashboard.i18n import t
+
+    captured: list[str] = []
+    monkeypatch.setattr(
+        mod.st, "markdown", lambda html, **kw: captured.append(str(html))
+    )
+
+    brief = {"quarter_deltas": [
+        _delta("risk_added", f"drift {i}") for i in range(6)
+    ]}
+    mod.render_summary(brief, limit=3)
+
+    joined = "".join(captured)
+
+    assert joined.count('class="primer-card"') == 3
+    assert "drift 0" in joined and "drift 1" in joined and "drift 2" in joined
+    assert "drift 3" not in joined
+    assert "drift 4" not in joined
+    assert "drift 5" not in joined
+    assert t("rl_summary_more").format(section=t("nav_signals")) in joined
+
+
+def test_render_summary_shows_the_tone_strip_and_the_empty_state_for_a_tone_only_brief(
+    monkeypatch,
+):
+    """Ruling A-8's path at the render level, not just the order level:
+    tone_trend is excluded from top_deltas, so a tone-only brief must still
+    produce the trajectory sparkline AND say plainly that no wording changed
+    -- rather than an empty panel or a silent no-op."""
+    import dashboard.redline_view as mod
+    import dashboard.tone_strip as tone_mod
+    from dashboard.i18n import t
+
+    captured: list[str] = []
+    monkeypatch.setattr(
+        mod.st, "markdown", lambda html, **kw: captured.append(str(html))
+    )
+    monkeypatch.setattr(
+        tone_mod.st, "markdown", lambda html, **kw: captured.append(str(html))
+    )
+
+    mod.render_summary({"quarter_deltas": [_tone_delta()]}, limit=3)
+
+    joined = "".join(captured)
+
+    assert "<svg" in joined
+    assert "hedging language" in joined
+    assert t("rl_summary_none") in joined
+    assert 'class="primer-card"' not in joined
+
+
+# ── render(): the zone dispatcher ───────────────────────────────────────────
+
+def test_render_keeps_zone_3_inside_the_expander_and_everything_else_above_it(
+    monkeypatch,
+):
+    """The one behaviour of render()'s dispatcher. Inverting
+    `if key in zone_3: continue` would ship the commodity reference blocks
+    above the fold and the differentiated ones inside a collapsed expander --
+    the precise inversion this sub-project exists to fix -- with a green
+    suite."""
+    from contextlib import contextmanager
+
+    import dashboard.verdict as mod
+
+    seen: list[str] = []
+
+    @contextmanager
+    def _expander(*args, **kwargs):
+        seen.append("<expander>")
+        yield None
+
+    monkeypatch.setattr(mod.st, "markdown", lambda *a, **kw: None)
+    monkeypatch.setattr(mod.st, "expander", _expander)
+    monkeypatch.setattr(
+        mod, "_block_renderers",
+        lambda brief, ticker: {
+            key: (lambda k=key: seen.append(k))
+            for key in (*mod.ZONE_1, *mod.ZONE_2, *mod.ZONE_3)
+        },
+    )
+
+    brief = _full_brief()
+    mod.render(brief)
+
+    order = mod.brief_block_order(brief)
+    boundary = seen.index("<expander>")
+    above = seen[:boundary]
+    inside = seen[boundary + 1:]
+
+    assert inside, "the expander rendered nothing"
+    assert set(inside) == set(mod.ZONE_3)
+    assert set(above) == set(order) - set(mod.ZONE_3)
+    assert not set(above) & set(mod.ZONE_3)
+    # Order is preserved within each side, not merely partitioned.
+    assert above == [k for k in order if k not in set(mod.ZONE_3)]
+    assert inside == [k for k in order if k in set(mod.ZONE_3)]