Two-level Reports nav: Campaign dropdown, then Period dropdown

Replaces the single flat "Reporting Month" dropdown with two linked
ones - Campaign (LinkedIn Branding Campaign / Pilot Partner / CTA
Campaign), then Period, populated based on the campaign picked.
Dash's dropdown has no native nested submenu, so this is the standard
"pick a year, then a month" cascade instead of faking nesting in one
control.

LinkedIn Branding Campaign -> July/August/September/End of Campaign
(unchanged, same data as before). Pilot Partner -> October (unchanged).
CTA Campaign -> its 3 proposed phases by date (Nov 3-26, Dec 1-Jan 7,
Jan 12-Feb 4), each showing a "not approved yet" placeholder rather
than crashing - compute_period_stats()'s date parsing doesn't
understand "cta-phase-1" as a period key, so it's guarded the same way
"campaign-end" was guarded before that report was built out. Download
button is guarded the same way.

Dropdown structure only - no CTA Campaign report content built yet,
that's still pending approval.

Co-Authored-By: Claude Sonnet 5 <noreply@anthropic.com>

app.py

@@ -2179,16 +2179,54 @@ _REPORTS_PERIODS = [
     ("2026-07", "July 2026"),
     ("2026-08", "August 2026"),
     ("2026-09", "September 2026"),
-    ("2026-10", "October 2026"),
 ]
 _REPORTS_MONTH_OPTIONS = [{"label": label, "value": key} for key, label in _REPORTS_PERIODS]
 _REPORTS_DEFAULT_MONTH = "2026-07"
 
+# Two-level nav: pick a campaign, then a period within it - a flat dropdown stopped
+# making sense once campaigns stopped being "the same 3 calendar months" (the CTA
+# Campaign's periods are custom date ranges spanning two calendar months each, not
+# July/August/September). Dash's dcc.Dropdown has no native nested/flyout submenu,
+# so this is two linked dropdowns instead - the standard "pick a year, then a month"
+# pattern - rather than faking nesting inside one control.
+_REPORTS_CAMPAIGNS = {
+    "linkedin-branding": {
+        "label": "LinkedIn Branding Campaign",
+        "periods": _REPORTS_PERIODS + [("campaign-end", "End of Campaign")],
+    },
+    "pilot-partner": {
+        "label": "Pilot Partner",
+        "periods": [("2026-10", "October 2026")],
+    },
+    "cta-campaign": {
+        "label": "CTA Campaign",
+        # Placeholder periods only - dates from the proposed plan, not yet approved.
+        # Selecting one shows a "not built yet" placeholder (_render_reports_tab),
+        # same treatment "End of Campaign" itself got before it was built out.
+        "periods": [
+            ("cta-phase-1", "Nov 3 - Nov 26 (Failure Analysis)"),
+            ("cta-phase-2", "Dec 1 - Jan 7 (Standardization)"),
+            ("cta-phase-3", "Jan 12 - Feb 4 (WaveGate)"),
+        ],
+    },
+}
+_REPORTS_CAMPAIGN_OPTIONS = [{"label": v["label"], "value": k} for k, v in _REPORTS_CAMPAIGNS.items()]
+_REPORTS_DEFAULT_CAMPAIGN = "linkedin-branding"
+
 reports_tab = dbc.Container([
     html.Div([
         html.Div([
-            html.Label("Reporting Month", style={"fontSize": "0.75rem", "fontWeight": "600",
-                                                   "marginBottom": "4px", "display": "block"}),
+            html.Label("Campaign", style={"fontSize": "0.75rem", "fontWeight": "600",
+                                           "marginBottom": "4px", "display": "block"}),
+            dcc.Dropdown(
+                id="reports-campaign-select",
+                options=_REPORTS_CAMPAIGN_OPTIONS, value=_REPORTS_DEFAULT_CAMPAIGN,
+                clearable=False, searchable=False, style={"width": "240px"},
+            ),
+        ], style={"marginRight": "0.75rem"}),
+        html.Div([
+            html.Label("Period", style={"fontSize": "0.75rem", "fontWeight": "600",
+                                         "marginBottom": "4px", "display": "block"}),
             dcc.Dropdown(
                 id="reports-month-select",
                 options=_REPORTS_MONTH_OPTIONS, value=_REPORTS_DEFAULT_MONTH,
@@ -4449,6 +4487,22 @@ def _render_campaign_end_summary():
     return title, html.Div(body, style={"fontSize": "0.9rem"})
 
 
+@app.callback(
+    Output("reports-month-select", "options"),
+    Output("reports-month-select", "value"),
+    Input("reports-campaign-select", "value"),
+)
+def _sync_reports_period_options(campaign_value):
+    """Picking a campaign repopulates the Period dropdown with just that campaign's
+    own periods (its own custom date ranges for CTA Campaign, calendar months for
+    the other two), defaulting to the first one - the standard "pick a year, then
+    a month" cascade, not a real nested submenu (Dash's dropdown has none)."""
+    periods = _REPORTS_CAMPAIGNS.get(campaign_value, {}).get("periods", [])
+    options = [{"label": label, "value": key} for key, label in periods]
+    default_value = periods[0][0] if periods else None
+    return options, default_value
+
+
 @app.callback(
     Output("reports-title", "children"),
     Output("reports-content-area", "children"),
@@ -4468,6 +4522,20 @@ def _render_reports_tab(month_value):
     if month_value == "campaign-end":
         return _render_campaign_end_summary() + (store_value,)
 
+    if month_value.startswith("cta-phase"):
+        # CTA Campaign is proposed, not yet approved — placeholder only, same
+        # treatment "End of Campaign" itself got before it was built out.
+        period_label = next((lbl for v, lbl in _REPORTS_CAMPAIGNS["cta-campaign"]["periods"]
+                              if v == month_value), month_value)
+        title = html.H3(f"CTA Campaign — {period_label}",
+                         style={"color": "#1b3a5c", "marginBottom": "0", "fontWeight": "700",
+                                "fontSize": "2rem", "whiteSpace": "nowrap"})
+        placeholder = dbc.Alert(
+            "The CTA Campaign hasn't been approved yet, so there's no report to show. "
+            "This period will build out the same way the other reports do once it's live.",
+            color="info")
+        return title, placeholder, no_update
+
     stats = report.compute_period_stats(_build_report_ctx(), month_value)
     notes = monthly_report_notes.NOTES.get(month_value)
     fts_f, posts_f = stats["fts_f"], stats["posts_f"]
@@ -4702,6 +4770,8 @@ def _render_reports_tab(month_value):
     prevent_initial_call=True,
 )
 def _download_reports_pdf(_n_clicks, month_value):
+    if month_value and month_value.startswith("cta-phase"):
+        return no_update  # CTA Campaign not approved yet, nothing to download
     ctx_data = _build_report_ctx()
     ctx_data["monthly_notes"] = monthly_report_notes.NOTES.get(month_value)
     docx_bytes = report.build_report_docx(ctx_data, month_value)