diff --git a/js/reactionCounter.js b/js/reactionCounter.js
index 0e2b9a51..0dfed685 100644
--- a/js/reactionCounter.js
+++ b/js/reactionCounter.js
@@ -1,6 +1,241 @@
 import { publishVideoReaction } from "./nostr.js";
+import { normalizePointerInput, pointerKey } from "./nostr/watchHistory.js";
 import { devLogger, userLogger } from "./utils/logger.js";
 
+const pointerStates = new Map();
+const pointerHandlers = new Map();
+
+function clonePointerDescriptor(pointer) {
+  if (!pointer || typeof pointer !== "object") {
+    return null;
+  }
+  const descriptor = {
+    type: pointer.type === "a" ? "a" : "e",
+    value:
+      typeof pointer.value === "string" && pointer.value.trim()
+        ? pointer.value.trim()
+        : "",
+  };
+  if (typeof pointer.relay === "string" && pointer.relay.trim()) {
+    descriptor.relay = pointer.relay.trim();
+  }
+  return descriptor;
+}
+
+function canonicalizePointerForState(pointerInput) {
+  const normalized = normalizePointerInput(pointerInput);
+  if (!normalized) {
+    return null;
+  }
+  const key = pointerKey(normalized);
+  if (!key) {
+    return null;
+  }
+  const descriptor = clonePointerDescriptor(normalized);
+  return descriptor ? { key, pointer: descriptor } : null;
+}
+
+function ensurePointerState(key, pointer) {
+  let state = pointerStates.get(key);
+  if (!state) {
+    state = {
+      pointer: pointer ? clonePointerDescriptor(pointer) : null,
+      totals: new Map(),
+      reactionsByPubkey: new Map(),
+      lastUpdatedAt: 0,
+    };
+    pointerStates.set(key, state);
+    return state;
+  }
+  if (pointer) {
+    const descriptor = clonePointerDescriptor(pointer);
+    if (!state.pointer) {
+      state.pointer = descriptor;
+    } else if (descriptor?.relay && !state.pointer.relay) {
+      state.pointer = { ...state.pointer, relay: descriptor.relay };
+    }
+  }
+  return state;
+}
+
+function normalizeReactionEvent(event) {
+  if (!event || typeof event !== "object") {
+    return null;
+  }
+  const pubkey =
+    typeof event.pubkey === "string" && event.pubkey.trim()
+      ? event.pubkey.trim().toLowerCase()
+      : "";
+  if (!pubkey) {
+    return null;
+  }
+  let content = "+";
+  if (typeof event.content === "string") {
+    content = event.content;
+  } else if (event.content !== undefined && event.content !== null) {
+    try {
+      content = String(event.content);
+    } catch (error) {
+      content = "+";
+    }
+  }
+  if (!content) {
+    content = "+";
+  }
+  const createdAt = Number.isFinite(event.created_at)
+    ? Math.max(0, Math.floor(event.created_at))
+    : 0;
+  const eventId =
+    typeof event.id === "string" && event.id.trim() ? event.id.trim() : "";
+  return { pubkey, content, created_at: createdAt, eventId };
+}
+
+function incrementContentCount(state, content) {
+  if (typeof content !== "string") {
+    return;
+  }
+  const existing = state.totals.get(content) || 0;
+  state.totals.set(content, existing + 1);
+}
+
+function decrementContentCount(state, content) {
+  if (typeof content !== "string") {
+    return;
+  }
+  const existing = state.totals.get(content);
+  if (!existing) {
+    return;
+  }
+  if (existing <= 1) {
+    state.totals.delete(content);
+  } else {
+    state.totals.set(content, existing - 1);
+  }
+}
+
+function applyReactionToState(key, pointer, event) {
+  const normalized = normalizeReactionEvent(event);
+  if (!normalized) {
+    return false;
+  }
+  const state = ensurePointerState(key, pointer);
+  const existing = state.reactionsByPubkey.get(normalized.pubkey);
+
+  if (existing) {
+    if (existing.created_at > normalized.created_at) {
+      return false;
+    }
+    if (
+      existing.created_at === normalized.created_at &&
+      existing.eventId &&
+      normalized.eventId &&
+      existing.eventId === normalized.eventId &&
+      existing.content === normalized.content
+    ) {
+      return false;
+    }
+    if (
+      existing.created_at === normalized.created_at &&
+      existing.eventId &&
+      !normalized.eventId &&
+      existing.content === normalized.content
+    ) {
+      return false;
+    }
+  }
+
+  let changed = false;
+  if (!existing) {
+    incrementContentCount(state, normalized.content);
+    changed = true;
+  } else {
+    if (existing.content !== normalized.content) {
+      decrementContentCount(state, existing.content);
+      incrementContentCount(state, normalized.content);
+      changed = true;
+    }
+  }
+
+  if (
+    !existing ||
+    existing.created_at !== normalized.created_at ||
+    existing.eventId !== normalized.eventId ||
+    existing.content !== normalized.content
+  ) {
+    state.reactionsByPubkey.set(normalized.pubkey, normalized);
+    state.lastUpdatedAt = Date.now();
+    if (!changed) {
+      changed = true;
+    }
+  }
+
+  return changed;
+}
+
+function snapshotState(state) {
+  const counts = {};
+  let total = 0;
+  for (const [content, count] of state.totals.entries()) {
+    counts[content] = count;
+    total += count;
+  }
+  const reactions = {};
+  for (const [pubkey, record] of state.reactionsByPubkey.entries()) {
+    reactions[pubkey] = {
+      content: record.content,
+      created_at: record.created_at,
+      eventId: record.eventId,
+    };
+  }
+  return {
+    pointer: state.pointer ? { ...state.pointer } : null,
+    total,
+    counts,
+    reactions,
+    lastUpdatedAt: state.lastUpdatedAt,
+  };
+}
+
+function notifyHandlers(key) {
+  const handlers = pointerHandlers.get(key);
+  if (!handlers || !handlers.size) {
+    return;
+  }
+  const state = pointerStates.get(key);
+  if (!state) {
+    return;
+  }
+  const snapshot = snapshotState(state);
+  for (const handler of handlers) {
+    if (typeof handler !== "function") {
+      continue;
+    }
+    try {
+      handler(snapshot);
+    } catch (error) {
+      userLogger.warn("[reactionCounter] Reaction handler threw:", error);
+    }
+  }
+}
+
+export function ingestLocalReaction({ event, pointer }) {
+  if (!event || !pointer) {
+    return;
+  }
+  try {
+    const canonical = canonicalizePointerForState(pointer);
+    if (!canonical) {
+      return;
+    }
+    const changed = applyReactionToState(canonical.key, canonical.pointer, event);
+    if (changed) {
+      notifyHandlers(canonical.key);
+    }
+  } catch (error) {
+    userLogger.warn("[reactionCounter] Failed to ingest local reaction:", error);
+  }
+}
+
 export const reactionCounter = {
   async publish(pointer, options = {}) {
     try {
@@ -94,6 +329,20 @@ export const reactionCounter = {
           `[reactionCounter] Reaction accepted by ${result.acceptedRelays.length} relay(s):`,
           result.acceptedRelays.join(", ")
         );
+        const eventPayload = result.event || {
+          pubkey:
+            typeof publishOptions.actorPubkey === "string"
+              ? publishOptions.actorPubkey
+              : undefined,
+          content: publishOptions.content,
+          created_at: publishOptions.created_at,
+        };
+        if (eventPayload && eventPayload.pubkey) {
+          ingestLocalReaction({
+            pointer: enrichedPointer,
+            event: eventPayload,
+          });
+        }
       }
       return result;
     } catch (error) {
@@ -103,4 +352,6 @@ export const reactionCounter = {
   },
 };
 
+reactionCounter.ingestLocalReaction = ingestLocalReaction;
+
 export default reactionCounter;