feat(messages): enhance message and edit history with channel names and content diffs

services/backend/src/modules/messages/messages.repository.ts

@@ -469,17 +469,20 @@ export class MessagesRepository {
     const db = getDatabase();
     const since = Date.now() - days * 24 * 60 * 60 * 1000;
     const result = await db.execute(sql`
-      SELECT channel_id,
-             EXTRACT(HOUR FROM to_timestamp(created_at / 1000))::int AS hour,
-             COUNT(*)::int AS c
-      FROM messages
-      WHERE created_at >= ${since}
-      GROUP BY channel_id, hour
-      ORDER BY channel_id, hour
+      SELECT
+        m.channel_id,
+        COALESCE(NULLIF((m.metadata::jsonb -> 'channel' ->> 'channelName'), ''), m.channel_id) AS channel_name,
+        EXTRACT(HOUR FROM to_timestamp(m.created_at / 1000))::int AS hour,
+        COUNT(*)::int AS c
+      FROM messages m
+      WHERE m.created_at >= ${since}
+      GROUP BY m.channel_id, channel_name, hour
+      ORDER BY channel_name, hour
     `);
     const rows = (result.rows as Record<string, unknown>[]) || [];
     return rows.map((r) => ({
       channelId: String(r.channel_id ?? "unknown"),
+      channelName: String(r.channel_name ?? r.channel_id ?? "unknown"),
       hour: Number(r.hour ?? 0),
       count: Number(r.c ?? 0),
     }));
@@ -499,7 +502,8 @@ export class MessagesRepository {
         e.edited_at,
         m.channel_id,
         COALESCE(NULLIF((m.metadata::jsonb -> 'channel' ->> 'channelName'), ''), m.channel_id) AS channel_name,
-        m.username
+        m.username,
+        m.content AS new_content
       FROM message_edits e
       JOIN messages m ON m.id = e.message_id
       ${channelId ? sql`WHERE m.channel_id = ${channelId}` : sql``}
@@ -511,6 +515,7 @@ export class MessagesRepository {
       id: String(r.id),
       message_id: String(r.message_id),
       old_content: r.old_content ? String(r.old_content) : "",
+      new_content: r.new_content ? String(r.new_content) : "",
       edited_at: r.edited_at ? Number(r.edited_at) : 0,
       channel_id: r.channel_id ? String(r.channel_id) : null,
       channel_name: r.channel_name ? String(r.channel_name) : null,

services/frontend/src/app/(dashboard)/messages/view.tsx

@@ -4,6 +4,7 @@ import {
   AlertTriangle,
   Calendar,
   CheckCircle2,
+  History,
   Image as ImageIcon,
   Loader2,
   MessageSquare,
@@ -548,6 +549,10 @@ function MessageDetail({
 }) {
   const flags = safeParseJsonArray(m.ai_moderation_flags);
   const cats = safeParseJsonArray(m.ai_categories);
+  const editHistory =
+    (m as { edit_history?: Array<{ old_content: string; edited_at: number }> })
+      .edit_history ?? [];
+  const editCount = (m as { edit_count?: number }).edit_count ?? 0;
   return (
     <div className="space-y-3 text-sm">
       <div className="flex items-center gap-3">
@@ -595,6 +600,44 @@ function MessageDetail({
         </div>
       )}
 
+      {/* Edit history — before / after diff */}
+      {editCount > 0 && editHistory.length > 0 && (
+        <div>
+          <div className="eyebrow mb-1.5 flex items-center gap-1.5">
+            <History className="size-3" /> Edit history ({editCount})
+          </div>
+          <div className="space-y-2">
+            {editHistory.map((e, i) => (
+              <div
+                key={`${m.id}-edit-${i}`}
+                className="grid grid-cols-2 gap-1.5 rounded-[6px] border border-hairline bg-surface-2/50 text-[10px] leading-relaxed"
+              >
+                <div className="overflow-hidden rounded-l-[5px] border-r border-hairline">
+                  <div className="border-b border-hairline bg-vermilion/5 px-2 py-0.5 font-mono text-[8px] font-semibold uppercase tracking-wider text-vermilion">
+                    Before
+                  </div>
+                  <div className="max-h-20 overflow-y-auto p-1.5">
+                    <pre className="whitespace-pre-wrap break-words text-ink-faint/80">
+                      {e.old_content || <em>(empty)</em>}
+                    </pre>
+                  </div>
+                </div>
+                <div className="overflow-hidden rounded-r-[5px]">
+                  <div className="border-b border-hairline bg-success/5 px-2 py-0.5 font-mono text-[8px] font-semibold uppercase tracking-wider text-success">
+                    After
+                  </div>
+                  <div className="max-h-20 overflow-y-auto p-1.5">
+                    <pre className="whitespace-pre-wrap break-words text-ink-soft">
+                      {m.content || <em>(empty)</em>}
+                    </pre>
+                  </div>
+                </div>
+              </div>
+            ))}
+          </div>
+        </div>
+      )}
+
       {attachments.length > 0 && (
         <div>
           <div className="eyebrow mb-1 flex items-center gap-1.5">

services/frontend/src/components/ActivityHeatmap.tsx

@@ -1,35 +1,62 @@
 "use client";
 
+import { useMemo } from "react";
 import { GlassPanel } from "@/components/primitives";
 import { SectionHeader } from "@/components/shared";
 import type { MessageActivityBucket } from "@/lib/types";
 
 const HOURS = Array.from({ length: 24 }, (_, i) => i);
 
+/** Neutral palette: dark slate → signal teal. No brand color for quiet data. */
 function heatColor(t: number): string {
-  // t in [0,1] → signal gradient (dark → bright).
-  if (t <= 0) return "var(--color-hairline)";
-  return `rgba(45, 212, 191, ${0.15 + 0.85 * t})`;
+  if (t <= 0) return "var(--color-surface-2)";
+  // 4 stops: subtle → medium → bright → full
+  if (t < 0.25) return "rgba(45, 212, 191, 0.10)";
+  if (t < 0.5) return "rgba(45, 212, 191, 0.25)";
+  if (t < 0.75) return "rgba(45, 212, 191, 0.50)";
+  return "rgba(45, 212, 191, 0.85)";
 }
 
+const HOUR_MARKS = [0, 4, 8, 12, 16, 20, 23];
+
 export function ActivityHeatmap({
   buckets,
 }: {
   buckets: MessageActivityBucket[];
 }) {
-  // Group by channel, find max count for normalization.
-  const channels = Array.from(new Set(buckets.map((b) => b.channelId)));
-  const byKey = new Map<string, number>();
-  let max = 0;
-  for (const b of buckets) {
-    const k = `${b.channelId}:${b.hour}`;
-    byKey.set(k, (byKey.get(k) ?? 0) + b.count);
-    if ((byKey.get(k) ?? 0) > max) max = byKey.get(k) ?? 0;
-  }
+  // Group by channel, normalise per-channel for better contrast.
+  const { rows, globalMax } = useMemo(() => {
+    const byKey = new Map<string, number>();
+    const channelNames = new Map<string, string>();
+    let gMax = 0;
 
-  if (buckets.length === 0) {
+    for (const b of buckets) {
+      const k = `${b.channelId}:${b.hour}`;
+      const next = (byKey.get(k) ?? 0) + b.count;
+      byKey.set(k, next);
+      channelNames.set(b.channelId, b.channelName);
+      if (next > gMax) gMax = next;
+    }
+
+    const rows = Array.from(channelNames.entries())
+      .map(([id, name]) => ({
+        id,
+        name,
+        cells: HOURS.map((h) => byKey.get(`${id}:${h}`) ?? 0),
+      }))
+      // Sort by total descending so busiest channel is on top
+      .sort((a, b) => {
+        const sumA = a.cells.reduce((s, v) => s + v, 0);
+        const sumB = b.cells.reduce((s, v) => s + v, 0);
+        return sumB - sumA;
+      });
+
+    return { rows, globalMax: gMax };
+  }, [buckets]);
+
+  if (rows.length === 0) {
     return (
-      <GlassPanel className="lg:col-span-2">
+      <GlassPanel>
         <SectionHeader eyebrow="insight" title="Activity Heatmap" />
         <p className="py-6 text-center text-xs text-ink-faint">
           No message activity recorded yet.
@@ -39,49 +66,81 @@ export function ActivityHeatmap({
   }
 
   return (
-    <GlassPanel className="lg:col-span-5">
+    <GlassPanel>
       <SectionHeader
         eyebrow="insight"
         title="Activity Heatmap"
         action={
-          <span className="mono text-[0.65rem] text-ink-faint">
-            {channels.length} channels · messages/hour
+          <span className="mono text-[10px] text-ink-faint">
+            {rows.length} channels · {globalMax} peak msgs/hr
           </span>
         }
       />
       <div className="overflow-x-auto">
-        <div className="min-w-[640px] space-y-1">
-          {channels.map((ch) => (
-            <div key={ch} className="flex items-center gap-2">
-              <span className="mono w-24 shrink-0 truncate text-[0.6rem] text-ink-faint">
-                {ch.slice(-6)}
-              </span>
-              <div className="flex flex-1 gap-0.5">
-                {HOURS.map((h) => {
-                  const c = byKey.get(`${ch}:${h}`) ?? 0;
-                  const t = max > 0 ? c / max : 0;
-                  return (
-                    <div
-                      key={h}
-                      title={`${ch} · ${String(h).padStart(2, "0")}:00 — ${c} msgs`}
-                      className="h-4 flex-1 rounded-[2px]"
-                      style={{ background: heatColor(t) }}
-                    />
-                  );
-                })}
-              </div>
-            </div>
-          ))}
-          <div className="flex items-center gap-2 pt-1">
-            <span className="w-24 shrink-0" />
-            <div className="flex flex-1 justify-between">
-              {[0, 6, 12, 18, 23].map((h) => (
-                <span key={h} className="mono text-[0.55rem] text-ink-faint">
-                  {String(h).padStart(2, "0")}h
+        <div className="min-w-[600px]">
+          {/* Column headers — hour labels */}
+          <div className="mb-1 flex items-center gap-2">
+            <span className="w-28 shrink-0" />
+            <div className="flex flex-1 justify-between px-px">
+              {HOUR_MARKS.map((h) => (
+                <span
+                  key={h}
+                  className="mono text-[9px] text-ink-faint tabular-nums"
+                >
+                  {String(h).padStart(2, "0")}
                 </span>
               ))}
             </div>
           </div>
+
+          {/* Rows */}
+          <div className="space-y-0.5">
+            {rows.map((row) => (
+              <div key={row.id} className="flex items-center gap-2">
+                <span
+                  className="w-28 shrink-0 truncate text-[10px] text-ink-muted"
+                  title={row.name}
+                >
+                  {row.name}
+                </span>
+                <div className="flex flex-1 gap-px">
+                  {row.cells.map((count, h) => {
+                    // Per-channel normalisation for better local contrast
+                    const chMax = Math.max(...row.cells, 1);
+                    const t = count / chMax;
+                    return (
+                      <div
+                        key={h}
+                        title={`${row.name} · ${String(h).padStart(2, "0")}:00 — ${count} msgs`}
+                        className="h-5 flex-1 rounded-[2px] transition-colors hover:ring-1 hover:ring-signal/40"
+                        style={{ background: heatColor(t) }}
+                      />
+                    );
+                  })}
+                </div>
+                {/* Row total */}
+                <span className="w-10 shrink-0 text-right font-mono text-[9px] text-ink-faint tabular-nums">
+                  {row.cells.reduce((s, v) => s + v, 0)}
+                </span>
+              </div>
+            ))}
+          </div>
+
+          {/* Legend */}
+          <div className="mt-2 flex items-center gap-2">
+            <span className="w-28 shrink-0" />
+            <div className="flex items-center gap-1.5 text-[9px] text-ink-faint">
+              <span>Less</span>
+              {[0, 0.15, 0.35, 0.6, 0.9].map((t) => (
+                <div
+                  key={t}
+                  className="h-3 w-3 rounded-[2px]"
+                  style={{ background: heatColor(t) }}
+                />
+              ))}
+              <span>More</span>
+            </div>
+          </div>
         </div>
       </div>
     </GlassPanel>

services/frontend/src/components/EditHistory.tsx

@@ -1,12 +1,68 @@
 "use client";
 
-import { Download, History } from "lucide-react";
+import { ArrowRight, Download, History } from "lucide-react";
 import { GlassPanel } from "@/components/primitives";
 import { SectionHeader } from "@/components/shared";
 import { downloadCsv } from "@/lib/csv";
 import { formatRelativeTime } from "@/lib/format";
 import type { EditHistoryRow } from "@/lib/types";
 
+function DiffBlock({ oldText, newText }: { oldText: string; newText: string }) {
+  const oldLines = oldText.split("\n");
+  const newLines = newText.split("\n");
+  const maxLen = Math.max(oldLines.length, newLines.length);
+
+  return (
+    <div className="grid grid-cols-2 gap-2 rounded-[6px] border border-hairline bg-surface-2/50 text-[11px] leading-relaxed">
+      {/* Before */}
+      <div className="min-w-0 overflow-hidden rounded-l-[5px] border-r border-hairline">
+        <div className="flex items-center gap-1.5 border-b border-hairline bg-vermilion/5 px-2.5 py-1">
+          <span className="font-mono text-[9px] font-semibold uppercase tracking-wider text-vermilion">
+            Before
+          </span>
+        </div>
+        <div className="max-h-24 overflow-y-auto p-2">
+          {oldLines.length === 0 || (oldLines.length === 1 && !oldLines[0]) ? (
+            <span className="italic text-ink-faint">(empty)</span>
+          ) : (
+            oldLines.map((line, i) => (
+              <div
+                key={`o-${i}`}
+                className="whitespace-pre-wrap break-words text-ink-faint/80"
+              >
+                {line}
+              </div>
+            ))
+          )}
+        </div>
+      </div>
+
+      {/* After */}
+      <div className="min-w-0 overflow-hidden rounded-r-[5px]">
+        <div className="flex items-center gap-1.5 border-b border-hairline bg-success/5 px-2.5 py-1">
+          <span className="font-mono text-[9px] font-semibold uppercase tracking-wider text-success">
+            After
+          </span>
+        </div>
+        <div className="max-h-24 overflow-y-auto p-2">
+          {newLines.length === 0 || (newLines.length === 1 && !newLines[0]) ? (
+            <span className="italic text-ink-faint">(empty)</span>
+          ) : (
+            newLines.map((line, i) => (
+              <div
+                key={`n-${i}`}
+                className="whitespace-pre-wrap break-words text-ink-soft"
+              >
+                {line}
+              </div>
+            ))
+          )}
+        </div>
+      </div>
+    </div>
+  );
+}
+
 export function EditHistory({ edits }: { edits: EditHistoryRow[] }) {
   return (
     <GlassPanel className="lg:col-span-4">
@@ -24,6 +80,7 @@ export function EditHistory({ edits }: { edits: EditHistoryRow[] }) {
                     author: e.username ?? "",
                     channel: e.channel_name ?? "",
                     old_content: e.old_content,
+                    new_content: e.new_content,
                     edited_at: e.edited_at,
                   })),
                 )
@@ -41,24 +98,25 @@ export function EditHistory({ edits }: { edits: EditHistoryRow[] }) {
           No edited messages recorded recently.
         </p>
       ) : (
-        <div className="space-y-3">
+        <div className="space-y-4">
           {edits.map((e) => (
-            <div key={e.id} className="text-sm">
-              <div className="flex flex-wrap items-baseline justify-between gap-2">
-                <span className="font-medium text-ink">
+            <div key={e.id} className="space-y-2">
+              {/* Header row */}
+              <div className="flex flex-wrap items-center gap-2">
+                <span className="text-xs font-semibold text-ink">
                   {e.username ?? "unknown"}
                 </span>
-                <span className="text-xs text-ink-faint">
-                  edited {formatRelativeTime(e.edited_at)} ·{" "}
-                  {e.channel_name ?? e.channel_id ?? "unknown channel"}
+                <span className="flex items-center gap-1 text-[10px] text-ink-muted">
+                  <History className="size-3 text-ink-faint/50" />
+                  edited {formatRelativeTime(e.edited_at)}
+                </span>
+                <span className="ml-auto font-mono text-[10px] text-ink-faint">
+                  {e.channel_name ?? e.channel_id ?? ""}
                 </span>
               </div>
-              <div className="mt-1 flex items-start gap-1.5">
-                <History className="mt-0.5 size-3.5 shrink-0 text-ink-faint/50" />
-                <pre className="line-clamp-2 whitespace-pre-wrap break-words text-ink-faint/80">
-                  {e.old_content || <em>(content not available)</em>}
-                </pre>
-              </div>
+
+              {/* Before / After diff */}
+              <DiffBlock oldText={e.old_content} newText={e.new_content} />
             </div>
           ))}
         </div>

services/frontend/src/lib/types/knowledge.ts

@@ -18,6 +18,7 @@ export interface EditHistoryRow {
   id: string;
   message_id: string;
   old_content: string;
+  new_content: string;
   edited_at: number;
   channel_id: string | null;
   channel_name: string | null;

services/frontend/src/lib/types/message.ts

@@ -175,6 +175,7 @@ export interface SemanticSearchResult {
 
 export interface MessageActivityBucket {
   channelId: string;
+  channelName: string;
   hour: number;
   count: number;
 }