feat(reports): dimension-switchable bar strip (period/payees/tags)

Segmented pill control with sliding indicator; pills disabled when the
report has <=1 distinct value for that dim. Bars show top 10 by |sum|
in a fixed-height view paged by chevrons (hidden scrollbar); widths are
magnitude-based so all-outflow slices render correctly.

src/Reports/ReportViewer.tsx

@@ -1,14 +1,19 @@
-import React, { useEffect, useMemo, useRef, useState } from "react";
+import React, { useCallback, useEffect, useMemo, useRef, useState } from "react";
 import { Box, Paper, Typography, Button, IconButton, Alert, Skeleton, Chip, MenuItem, Select, FormControl, InputLabel } from "@mui/material";
 import CloseIcon from "@mui/icons-material/Close";
 import CachedIcon from "@mui/icons-material/Cached";
+import KeyboardArrowDownIcon from "@mui/icons-material/KeyboardArrowDown";
+import KeyboardArrowUpIcon from "@mui/icons-material/KeyboardArrowUp";
 import { FkMultiSelectField, useResource, formatCurrency } from "../../react-openapi";
 import type { FieldConfig } from "../../react-openapi";
 import { StatCard } from "../common/components/StatCard";
 import { TransactionList } from "../common/components/TransactionList";
 import type { TxnFieldConfigs } from "../common/types";
 import type { ListPeriodGroup } from "../common/utils/transactions";
-import { buildPeriodGroups, sliceSummary, FLOW_OPTIONS, apiErrorMessage } from "./types";
+import { buildDimensionBars, buildPeriodGroups, sliceSummary, FLOW_OPTIONS, apiErrorMessage } from "./types";
+import type { ReportDim } from "./types";
+
+const MAX_VISIBLE_BARS = 10;
 
 const periodField: FieldConfig = {
   name: "period",
@@ -78,6 +83,7 @@ export function ReportViewer({ id, version, fields, onClose, onRegenerated }: Re
   const [reload, setReload] = useState(0);
   const [granularity, setGranularity] = useState<string | null>(null);
   const [flow, setFlow] = useState("outflows");
+  const [dim, setDim] = useState<ReportDim>("period");
   const [selectedPeriods, setSelectedPeriods] = useState<string[]>([]);
   const [selectedPayees, setSelectedPayees] = useState<string[]>([]);
   const [selectedTags, setSelectedTags] = useState<string[]>([]);
@@ -145,6 +151,8 @@ export function ReportViewer({ id, version, fields, onClose, onRegenerated }: Re
 
   const periodGroups = useMemo(() => buildPeriodGroups(report?.buckets ?? [], filter), [report, filter]);
   const slice = useMemo(() => sliceSummary(periodGroups), [periodGroups]);
+  const bars = useMemo(() => buildDimensionBars(report?.buckets ?? [], filter, dim), [report, filter, dim]);
+  const visibleBars = useMemo(() => bars.slice(0, MAX_VISIBLE_BARS), [bars]);
   const listGroups = useMemo<ListPeriodGroup[]>(
     () =>
       periodGroups.map((g) => ({
@@ -167,6 +175,32 @@ export function ReportViewer({ id, version, fields, onClose, onRegenerated }: Re
     [periodGroups],
   );
 
+  const barsListRef = useRef<HTMLDivElement>(null);
+  const [barScroll, setBarScroll] = useState({ canUp: false, canDown: false, overflow: false });
+
+  const updateBarScroll = useCallback(() => {
+    const el = barsListRef.current;
+    if (!el) return;
+    const overflow = el.scrollHeight > el.clientHeight + 2;
+    setBarScroll({
+      overflow,
+      canUp: overflow && el.scrollTop > 2,
+      canDown: overflow && el.scrollTop < el.scrollHeight - el.clientHeight - 2,
+    });
+  }, []);
+
+  useEffect(() => {
+    const el = barsListRef.current;
+    if (el) el.scrollTop = 0;
+    updateBarScroll();
+  }, [dim, visibleBars.length, updateBarScroll]);
+
+  const scrollBarsByPage = useCallback((dir: number) => {
+    const el = barsListRef.current;
+    if (!el) return;
+    el.scrollTo({ top: dir > 0 ? el.scrollHeight : 0, behavior: "smooth" });
+  }, []);
+
   if (loading && !report) {
     return (
       <Paper variant="outlined" sx={{ p: 2.5, borderRadius: 3 }}>
@@ -193,7 +227,16 @@ export function ReportViewer({ id, version, fields, onClose, onRegenerated }: Re
   if (!report) return null;
 
   const activeGranularity = granularity ?? report.granularities?.[0] ?? "";
-  const maxBar = periodGroups.reduce((m, g) => Math.max(m, g.metrics.sum), 0);
+  const maxBar = bars.reduce((m, b) => Math.max(m, Math.abs(b.sum)), 0);
+  const dimOptions: { id: ReportDim; label: string; count: number }[] = [
+    { id: "period", label: "Period", count: report.period_ids?.length ?? 0 },
+    { id: "payee", label: "Payees", count: report.payees?.length ?? 0 },
+    { id: "tag", label: "Tags", count: report.tags?.length ?? 0 },
+  ];
+  const activeDimIndex = Math.max(
+    0,
+    dimOptions.findIndex((d) => d.id === dim),
+  );
   const range =
     report.query?.start_date || report.query?.end_date
       ? `range ${report.query.start_date || "…"} → ${report.query.end_date || "…"}`
@@ -303,39 +346,148 @@ export function ReportViewer({ id, version, fields, onClose, onRegenerated }: Re
           <StatCard label="Transactions" value={slice.count.toLocaleString("en-IN")} />
         </Box>
 
-        {periodGroups.length === 0 ? (
-          <Paper variant="outlined" sx={{ borderRadius: 2, p: 3, mb: 2.5 }}>
-            <Typography variant="body2" color="text.secondary">
-              No data for this slice. Try another granularity, period or payer.
-            </Typography>
-          </Paper>
-        ) : (
-          <Paper variant="outlined" sx={{ borderRadius: 2, p: 2, mb: 2.5 }}>
-            {periodGroups.map((g) => (
-              <Box key={g.key} sx={{ display: "flex", alignItems: "center", gap: 1.5, py: 0.75 }}>
-                <Typography variant="caption" sx={{ width: 110, flexShrink: 0, textAlign: "right" }}>
-                  {g.key}
-                </Typography>
+        <Box sx={{ mb: 2.5 }}>
+          <Box
+            sx={{
+              position: "relative",
+              display: "flex",
+              alignItems: "stretch",
+              width: "fit-content",
+              maxWidth: "100%",
+              border: "1px solid",
+              borderColor: "divider",
+              borderRadius: "999px",
+              p: 0.5,
+              backgroundColor: "background.default",
+            }}
+          >
+            <Box
+              aria-hidden
+              sx={{
+                position: "absolute",
+                top: 4,
+                bottom: 4,
+                left: 4,
+                width: `calc((100% - 8px) / ${dimOptions.length})`,
+                borderRadius: "999px",
+                backgroundColor: "primary.main",
+                transform: `translateX(${activeDimIndex * 100}%)`,
+                transition: "transform 250ms cubic-bezier(0.4, 0, 0.2, 1)",
+              }}
+            />
+            {dimOptions.map((d) => {
+              const active = d.id === dim;
+              return (
                 <Box
+                  key={d.id}
+                  component="button"
+                  type="button"
+                  disabled={d.count <= 1}
+                  onClick={() => setDim(d.id)}
                   sx={{
-                    height: 20,
-                    borderRadius: 1,
-                    bgcolor: flow === "outflows" ? "error.main" : "success.main",
-                    opacity: 0.85,
-                    minWidth: 4,
+                    position: "relative",
+                    zIndex: 1,
+                    flex: 1,
+                    border: "none",
+                    background: "transparent",
+                    px: 3,
+                    py: 1,
+                    borderRadius: "999px",
+                    cursor: d.count <= 1 ? "default" : "pointer",
+                    typography: "body2",
+                    fontWeight: 700,
+                    letterSpacing: "-0.01em",
+                    color:
+                      d.count <= 1
+                        ? "text.disabled"
+                        : active
+                          ? "primary.contrastText"
+                          : "text.secondary",
+                    whiteSpace: "nowrap",
+                    transition: "color 160ms ease",
+                    "&:focus-visible": { outline: "2px solid", outlineColor: "primary.main" },
                   }}
-                  style={{ width: `${maxBar ? Math.max((g.metrics.sum / maxBar) * 100, 2) : 2}%` }}
-                />
-                <Typography variant="body2" fontWeight={600}>
-                  {formatCurrency(g.metrics.sum, slice.currency)}
-                </Typography>
-                <Typography variant="caption" color="text.disabled">
-                  {g.metrics.count} txn{g.metrics.count === 1 ? "" : "s"}
-                </Typography>
+                >
+                  {d.label}
+                </Box>
+              );
+            })}
+          </Box>
+
+          {visibleBars.length === 0 ? (
+            <Paper variant="outlined" sx={{ borderRadius: 2, p: 3, mt: 1.5 }}>
+              <Typography variant="body2" color="text.secondary">
+                No data for this slice. Try another granularity, period or payer.
+              </Typography>
+            </Paper>
+          ) : (
+            <Paper variant="outlined" sx={{ borderRadius: 2, mt: 1.5 }}>
+              <Box sx={{ display: "flex", alignItems: "stretch" }}>
+                <Box
+                  ref={barsListRef}
+                  onScroll={updateBarScroll}
+                  sx={{
+                    flex: 1,
+                    minWidth: 0,
+                    maxHeight: 220,
+                    overflowY: "auto",
+                    py: 1,
+                    px: 2,
+                    scrollbarWidth: "none",
+                    "&::-webkit-scrollbar": { display: "none" },
+                  }}
+                >
+                  {visibleBars.map((b) => (
+                    <Box key={b.key} sx={{ display: "flex", alignItems: "center", gap: 1.5, py: 0.75 }}>
+                      <Typography variant="caption" sx={{ width: 110, flexShrink: 0, textAlign: "right" }}>
+                        {b.key}
+                      </Typography>
+                      <Box
+                        sx={{
+                          height: 20,
+                          borderRadius: 1,
+                          bgcolor: flow === "outflows" ? "error.main" : "success.main",
+                          opacity: 0.85,
+                          minWidth: 4,
+                          flexGrow: 0,
+                        }}
+                        style={{
+                          width: `${maxBar ? Math.max((Math.abs(b.sum) / maxBar) * 100, 2) : 2}%`,
+                        }}
+                      />
+                      <Typography variant="body2" fontWeight={600}>
+                        {formatCurrency(b.sum, slice.currency)}
+                      </Typography>
+                      <Typography variant="caption" color="text.disabled">
+                        {b.count} txn{b.count === 1 ? "" : "s"}
+                      </Typography>
+                    </Box>
+                  ))}
+                </Box>
+                {barScroll.overflow && (
+                  <Box sx={{ display: "flex", flexDirection: "column", justifyContent: "center", gap: 0.5, pr: 1.5 }}>
+                    <IconButton
+                      size="small"
+                      aria-label="Scroll bars up"
+                      disabled={!barScroll.canUp}
+                      onClick={() => scrollBarsByPage(-1)}
+                    >
+                      <KeyboardArrowUpIcon fontSize="small" />
+                    </IconButton>
+                    <IconButton
+                      size="small"
+                      aria-label="Scroll bars down"
+                      disabled={!barScroll.canDown}
+                      onClick={() => scrollBarsByPage(1)}
+                    >
+                      <KeyboardArrowDownIcon fontSize="small" />
+                    </IconButton>
+                  </Box>
+                )}
               </Box>
-            ))}
-          </Paper>
-        )}
+            </Paper>
+          )}
+        </Box>
 
         {slice.txns.length === 0 ? null : fields ? (
           <TransactionList fields={fields} groups={listGroups} showMetrics />

src/Reports/types.ts

@@ -231,4 +231,48 @@ export function buildReportFieldConfigs(resources: ResourceConfig[]): ReportFiel
   const generatedAt = find("generated_at");
   if (!name || !generatedAt) return null;
   return { name, generatedAt };
+}
+
+export type ReportDim = "period" | "payee" | "tag";
+
+export interface DimensionBar {
+  key: string;
+  sum: number;
+  count: number;
+}
+
+/**
+ * Bar-chart rows for a given dimension. "period" reuses the period groups;
+ * "payee"/"tag" fold each bucket's metrics into every value listed under
+ * group_key[dim] — safe because server buckets are disjoint slices.
+ */
+export function buildDimensionBars(buckets: any[], filter: SliceFilter, dim: ReportDim): DimensionBar[] {
+  if (dim === "period") {
+    return buildPeriodGroups(buckets, filter).map((g) => ({
+      key: g.key,
+      sum: g.metrics.sum,
+      count: g.metrics.count,
+    }));
+  }
+  const acc = new Map<string, DimensionBar>();
+  for (const bucket of buckets ?? []) {
+    if (!bucketMatches(bucket, filter)) continue;
+    const keys: string[] = bucket.group_key?.[dim] ?? [];
+    for (const period of bucket.series?.[filter.granularity] ?? []) {
+      if (filter.periods?.length && !filter.periods.includes(period.period_id)) continue;
+      const m = period.metrics ?? {};
+      const sum = typeof m.sum === "number" ? m.sum : 0;
+      const count = typeof m.count === "number" ? m.count : 0;
+      for (const k of keys) {
+        const cur = acc.get(k);
+        if (cur) {
+          cur.sum += sum;
+          cur.count += count;
+        } else {
+          acc.set(k, { key: k, sum, count });
+        }
+      }
+    }
+  }
+  return [...acc.values()].sort((a, b) => Math.abs(b.sum) - Math.abs(a.sum));
 }