feat(ui): coalesce streaming deltas and deduplicate live feed items

Merge consecutive assistant/thinking deltas into a single feed entry
instead of creating one per chunk. Add dedupeKey to FeedItem, increase
streaming text cap to 4000 chars, and bump seen-keys limit to 6000.
Applied consistently to both ActiveAgentsPanel and LiveRunWidget.

Co-Authored-By: Claude Opus 4.6 <noreply@anthropic.com>

ui/src/components/ActiveAgentsPanel.tsx

@@ -21,9 +21,13 @@ interface FeedItem {
   agentName: string;
   text: string;
   tone: FeedTone;
+  dedupeKey: string;
+  streamingKind?: "assistant" | "thinking";
 }
 
 const MAX_FEED_ITEMS = 40;
+const MAX_FEED_TEXT_LENGTH = 220;
+const MAX_STREAMING_TEXT_LENGTH = 4000;
 const MIN_DASHBOARD_RUNS = 4;
 
 function readString(value: unknown): string | null {
@@ -70,17 +74,25 @@ function createFeedItem(
   text: string,
   tone: FeedTone,
   nextId: number,
+  options?: {
+    streamingKind?: "assistant" | "thinking";
+    preserveWhitespace?: boolean;
+  },
 ): FeedItem | null {
-  const trimmed = text.trim();
+  if (!text.trim()) return null;
-  if (!trimmed) return null;
+  const base = options?.preserveWhitespace ? text : text.trim();
+  const maxLength = options?.streamingKind ? MAX_STREAMING_TEXT_LENGTH : MAX_FEED_TEXT_LENGTH;
+  const normalized = base.length > maxLength ? base.slice(-maxLength) : base;
   return {
     id: `${run.id}:${nextId}`,
     ts,
     runId: run.id,
     agentId: run.agentId,
     agentName: run.agentName,
-    text: trimmed.slice(0, 220),
+    text: normalized,
     tone,
+    dedupeKey: `feed:${run.id}:${ts}:${tone}:${normalized}`,
+    streamingKind: options?.streamingKind,
   };
 }
 
@@ -97,16 +109,16 @@ function parseStdoutChunk(
   pendingByRun.set(pendingKey, split.pop() ?? "");
   const adapter = getUIAdapter(run.adapterType);
 
-  const summarized: Array<{ text: string; tone: FeedTone; thinkingDelta?: boolean; assistantDelta?: boolean }> = [];
+  const summarized: Array<{ text: string; tone: FeedTone; streamingKind?: "assistant" | "thinking" }> = [];
   const appendSummary = (entry: TranscriptEntry) => {
     if (entry.kind === "assistant" && entry.delta) {
       const text = entry.text;
       if (!text.trim()) return;
       const last = summarized[summarized.length - 1];
-      if (last && last.assistantDelta) {
+      if (last && last.streamingKind === "assistant") {
         last.text += text;
       } else {
-        summarized.push({ text, tone: "assistant", assistantDelta: true });
+        summarized.push({ text, tone: "assistant", streamingKind: "assistant" });
       }
       return;
     }
@@ -115,10 +127,10 @@ function parseStdoutChunk(
       const text = entry.text;
       if (!text.trim()) return;
       const last = summarized[summarized.length - 1];
-      if (last && last.thinkingDelta) {
+      if (last && last.streamingKind === "thinking") {
         last.text += text;
       } else {
-        summarized.push({ text: `[thinking] ${text}`, tone: "info", thinkingDelta: true });
+        summarized.push({ text: `[thinking] ${text}`, tone: "info", streamingKind: "thinking" });
       }
       return;
     }
@@ -144,7 +156,10 @@ function parseStdoutChunk(
   }
 
   for (const summary of summarized) {
-    const item = createFeedItem(run, ts, summary.text, summary.tone, nextIdRef.current++);
+    const item = createFeedItem(run, ts, summary.text, summary.tone, nextIdRef.current++, {
+      streamingKind: summary.streamingKind,
+      preserveWhitespace: !!summary.streamingKind,
+    });
     if (item) items.push(item);
   }
 
@@ -234,8 +249,38 @@ export function ActiveAgentsPanel({ companyId }: ActiveAgentsPanelProps) {
       if (items.length === 0) return;
       setFeedByRun((prev) => {
         const next = new Map(prev);
-        const existing = next.get(runId) ?? [];
+        const existing = [...(next.get(runId) ?? [])];
-        next.set(runId, [...existing, ...items].slice(-MAX_FEED_ITEMS));
+        for (const item of items) {
+          if (seenKeysRef.current.has(item.dedupeKey)) continue;
+          seenKeysRef.current.add(item.dedupeKey);
+
+          const last = existing[existing.length - 1];
+          if (
+            item.streamingKind &&
+            last &&
+            last.runId === item.runId &&
+            last.streamingKind === item.streamingKind
+          ) {
+            const mergedText = `${last.text}${item.text}`;
+            const nextText =
+              mergedText.length > MAX_STREAMING_TEXT_LENGTH
+                ? mergedText.slice(-MAX_STREAMING_TEXT_LENGTH)
+                : mergedText;
+            existing[existing.length - 1] = {
+              ...last,
+              ts: item.ts,
+              text: nextText,
+              dedupeKey: last.dedupeKey,
+            };
+            continue;
+          }
+
+          existing.push(item);
+        }
+        if (seenKeysRef.current.size > 6000) {
+          seenKeysRef.current.clear();
+        }
+        next.set(runId, existing.slice(-MAX_FEED_ITEMS));
         return next;
       });
     };
@@ -277,7 +322,7 @@ export function ActiveAgentsPanel({ companyId }: ActiveAgentsPanelProps) {
           const dedupeKey = `${runId}:event:${seq ?? `${eventType}:${messageText}:${event.createdAt}`}`;
           if (seenKeysRef.current.has(dedupeKey)) return;
           seenKeysRef.current.add(dedupeKey);
-          if (seenKeysRef.current.size > 2000) seenKeysRef.current.clear();
+          if (seenKeysRef.current.size > 6000) seenKeysRef.current.clear();
           const tone = eventType === "error" ? "error" : eventType === "lifecycle" ? "warn" : "info";
           const item = createFeedItem(run, event.createdAt, messageText, tone, nextIdRef.current++);
           if (item) appendItems(run.id, [item]);
@@ -289,7 +334,7 @@ export function ActiveAgentsPanel({ companyId }: ActiveAgentsPanelProps) {
           const dedupeKey = `${runId}:status:${status}:${readString(payload["finishedAt"]) ?? ""}`;
           if (seenKeysRef.current.has(dedupeKey)) return;
           seenKeysRef.current.add(dedupeKey);
-          if (seenKeysRef.current.size > 2000) seenKeysRef.current.clear();
+          if (seenKeysRef.current.size > 6000) seenKeysRef.current.clear();
           const tone = status === "failed" || status === "timed_out" ? "error" : "warn";
           const item = createFeedItem(run, event.createdAt, `run ${status}`, tone, nextIdRef.current++);
           if (item) appendItems(run.id, [item]);

ui/src/components/LiveRunWidget.tsx

@@ -26,9 +26,13 @@ interface FeedItem {
   agentName: string;
   text: string;
   tone: FeedTone;
+  dedupeKey: string;
+  streamingKind?: "assistant" | "thinking";
 }
 
 const MAX_FEED_ITEMS = 80;
+const MAX_FEED_TEXT_LENGTH = 220;
+const MAX_STREAMING_TEXT_LENGTH = 4000;
 const LOG_POLL_INTERVAL_MS = 2000;
 const LOG_READ_LIMIT_BYTES = 256_000;
 
@@ -81,17 +85,25 @@ function createFeedItem(
   text: string,
   tone: FeedTone,
   nextId: number,
+  options?: {
+    streamingKind?: "assistant" | "thinking";
+    preserveWhitespace?: boolean;
+  },
 ): FeedItem | null {
-  const trimmed = text.trim();
+  if (!text.trim()) return null;
-  if (!trimmed) return null;
+  const base = options?.preserveWhitespace ? text : text.trim();
+  const maxLength = options?.streamingKind ? MAX_STREAMING_TEXT_LENGTH : MAX_FEED_TEXT_LENGTH;
+  const normalized = base.length > maxLength ? base.slice(-maxLength) : base;
   return {
     id: `${run.id}:${nextId}`,
     ts,
     runId: run.id,
     agentId: run.agentId,
     agentName: run.agentName,
-    text: trimmed.slice(0, 220),
+    text: normalized,
     tone,
+    dedupeKey: `feed:${run.id}:${ts}:${tone}:${normalized}`,
+    streamingKind: options?.streamingKind,
   };
 }
 
@@ -108,16 +120,16 @@ function parseStdoutChunk(
   pendingByRun.set(pendingKey, split.pop() ?? "");
   const adapter = getUIAdapter(run.adapterType);
 
-  const summarized: Array<{ text: string; tone: FeedTone; thinkingDelta?: boolean; assistantDelta?: boolean }> = [];
+  const summarized: Array<{ text: string; tone: FeedTone; streamingKind?: "assistant" | "thinking" }> = [];
   const appendSummary = (entry: TranscriptEntry) => {
     if (entry.kind === "assistant" && entry.delta) {
       const text = entry.text;
       if (!text.trim()) return;
       const last = summarized[summarized.length - 1];
-      if (last && last.assistantDelta) {
+      if (last && last.streamingKind === "assistant") {
         last.text += text;
       } else {
-        summarized.push({ text, tone: "assistant", assistantDelta: true });
+        summarized.push({ text, tone: "assistant", streamingKind: "assistant" });
       }
       return;
     }
@@ -126,10 +138,10 @@ function parseStdoutChunk(
       const text = entry.text;
       if (!text.trim()) return;
       const last = summarized[summarized.length - 1];
-      if (last && last.thinkingDelta) {
+      if (last && last.streamingKind === "thinking") {
         last.text += text;
       } else {
-        summarized.push({ text: `[thinking] ${text}`, tone: "info", thinkingDelta: true });
+        summarized.push({ text: `[thinking] ${text}`, tone: "info", streamingKind: "thinking" });
       }
       return;
     }
@@ -158,7 +170,10 @@ function parseStdoutChunk(
   }
 
   for (const summary of summarized) {
-    const item = createFeedItem(run, ts, summary.text, summary.tone, nextIdRef.current++);
+    const item = createFeedItem(run, ts, summary.text, summary.tone, nextIdRef.current++, {
+      streamingKind: summary.streamingKind,
+      preserveWhitespace: !!summary.streamingKind,
+    });
     if (item) items.push(item);
   }
 
@@ -291,18 +306,39 @@ export function LiveRunWidget({ issueId, companyId }: LiveRunWidgetProps) {
   const appendItems = (items: FeedItem[]) => {
     if (items.length === 0) return;
     setFeed((prev) => {
-      const deduped: FeedItem[] = [];
+      const next = [...prev];
       for (const item of items) {
-        const key = `feed:${item.runId}:${item.ts}:${item.tone}:${item.text}`;
+        if (seenKeysRef.current.has(item.dedupeKey)) continue;
-        if (seenKeysRef.current.has(key)) continue;
+        seenKeysRef.current.add(item.dedupeKey);
-        seenKeysRef.current.add(key);
+
-        deduped.push(item);
+        const last = next[next.length - 1];
+        if (
+          item.streamingKind &&
+          last &&
+          last.runId === item.runId &&
+          last.streamingKind === item.streamingKind
+        ) {
+          const mergedText = `${last.text}${item.text}`;
+          const nextText =
+            mergedText.length > MAX_STREAMING_TEXT_LENGTH
+              ? mergedText.slice(-MAX_STREAMING_TEXT_LENGTH)
+              : mergedText;
+          next[next.length - 1] = {
+            ...last,
+            ts: item.ts,
+            text: nextText,
+            dedupeKey: last.dedupeKey,
+          };
+          continue;
+        }
+
+        next.push(item);
       }
-      if (deduped.length === 0) return prev;
       if (seenKeysRef.current.size > 6000) {
         seenKeysRef.current.clear();
       }
-      return [...prev, ...deduped].slice(-MAX_FEED_ITEMS);
+      if (next.length === prev.length) return prev;
+      return next.slice(-MAX_FEED_ITEMS);
     });
   };