diff --git a/apps/server/events/types.ts b/apps/server/events/types.ts
index 2f4b84c..04162cf 100644
--- a/apps/server/events/types.ts
+++ b/apps/server/events/types.ts
@@ -694,6 +694,14 @@ export type DomainEventType = DomainEventMap['type'];
  *
  * All modules communicate through this interface.
  * Can be swapped for external systems (RabbitMQ, WebSocket forwarding) later.
+ *
+ * **Delivery guarantee: at-most-once.**
+ *
+ * Events emitted while a client is disconnected are permanently lost.
+ * Reconnecting clients receive only events emitted after reconnection.
+ * React Query's `refetchOnWindowFocus` and `refetchOnReconnect` compensate
+ * for missed mutations since the system uses query invalidation rather
+ * than incremental state.
  */
 export interface EventBus {
   /**
diff --git a/apps/server/trpc/routers/subscription.ts b/apps/server/trpc/routers/subscription.ts
index 949a011..43dfd79 100644
--- a/apps/server/trpc/routers/subscription.ts
+++ b/apps/server/trpc/routers/subscription.ts
@@ -2,7 +2,6 @@
  * Subscription Router — SSE event streams
  */
 
-import { z } from 'zod';
 import type { ProcedureBuilder } from '../trpc.js';
 import {
   eventBusIterable,
@@ -17,42 +16,40 @@ import {
 export function subscriptionProcedures(publicProcedure: ProcedureBuilder) {
   return {
     onEvent: publicProcedure
-      .input(z.object({ lastEventId: z.string().nullish() }).optional())
       .subscription(async function* (opts) {
         const signal = opts.signal ?? new AbortController().signal;
         yield* eventBusIterable(opts.ctx.eventBus, ALL_EVENT_TYPES, signal);
       }),
 
     onAgentUpdate: publicProcedure
-      .input(z.object({ lastEventId: z.string().nullish() }).optional())
       .subscription(async function* (opts) {
         const signal = opts.signal ?? new AbortController().signal;
         yield* eventBusIterable(opts.ctx.eventBus, AGENT_EVENT_TYPES, signal);
       }),
 
     onTaskUpdate: publicProcedure
-      .input(z.object({ lastEventId: z.string().nullish() }).optional())
       .subscription(async function* (opts) {
         const signal = opts.signal ?? new AbortController().signal;
         yield* eventBusIterable(opts.ctx.eventBus, TASK_EVENT_TYPES, signal);
       }),
 
     onPageUpdate: publicProcedure
-      .input(z.object({ lastEventId: z.string().nullish() }).optional())
       .subscription(async function* (opts) {
         const signal = opts.signal ?? new AbortController().signal;
         yield* eventBusIterable(opts.ctx.eventBus, PAGE_EVENT_TYPES, signal);
       }),
 
     onPreviewUpdate: publicProcedure
-      .input(z.object({ lastEventId: z.string().nullish() }).optional())
       .subscription(async function* (opts) {
         const signal = opts.signal ?? new AbortController().signal;
         yield* eventBusIterable(opts.ctx.eventBus, PREVIEW_EVENT_TYPES, signal);
       }),
 
+    // NOTE: No frontend view currently displays inter-agent conversation data.
+    // When a conversation view is added, add to its useLiveUpdates call:
+    //   { prefix: 'conversation:', invalidate: ['<query-key>'] }
+    // and add the relevant mutation(s) to INVALIDATION_MAP in apps/web/src/lib/invalidation.ts.
     onConversationUpdate: publicProcedure
-      .input(z.object({ lastEventId: z.string().nullish() }).optional())
       .subscription(async function* (opts) {
         const signal = opts.signal ?? new AbortController().signal;
         yield* eventBusIterable(opts.ctx.eventBus, CONVERSATION_EVENT_TYPES, signal);
diff --git a/apps/web/src/lib/invalidation.ts b/apps/web/src/lib/invalidation.ts
index d0c767f..3cd6e1f 100644
--- a/apps/web/src/lib/invalidation.ts
+++ b/apps/web/src/lib/invalidation.ts
@@ -56,8 +56,8 @@ const INVALIDATION_MAP: Partial<Record<MutationName, QueryName[]>> = {
   updatePhase: ["listPhases", "getPhase"],
   approvePhase: ["listPhases", "listInitiativeTasks"],
   queuePhase: ["listPhases"],
-  createPhaseDependency: ["getPhaseDependencies", "listInitiativePhaseDependencies"],
-  removePhaseDependency: ["getPhaseDependencies", "listInitiativePhaseDependencies"],
+  createPhaseDependency: ["getPhaseDependencies", "listInitiativePhaseDependencies", "listPhaseTaskDependencies"],
+  removePhaseDependency: ["getPhaseDependencies", "listInitiativePhaseDependencies", "listPhaseTaskDependencies"],
 
   // --- Tasks ---
   createPhaseTask: ["listPhaseTasks", "listInitiativeTasks", "listTasks"],
@@ -68,7 +68,7 @@ const INVALIDATION_MAP: Partial<Record<MutationName, QueryName[]>> = {
   deleteTask: ["listTasks", "listInitiativeTasks", "listPhaseTasks", "listChangeSets"],
 
   // --- Change Sets ---
-  revertChangeSet: ["listPhases", "listPhaseTasks", "listInitiativeTasks", "listPages", "getPage", "listChangeSets", "getRootPage"],
+  revertChangeSet: ["listPhases", "listPhaseTasks", "listInitiativeTasks", "listPages", "getPage", "listChangeSets", "getRootPage", "getChangeSet"],
 
   // --- Pages ---
   updatePage: ["listPages", "getPage", "getRootPage"],
diff --git a/apps/web/src/routes/initiatives/$id.tsx b/apps/web/src/routes/initiatives/$id.tsx
index 6662f18..678100c 100644
--- a/apps/web/src/routes/initiatives/$id.tsx
+++ b/apps/web/src/routes/initiatives/$id.tsx
@@ -29,11 +29,12 @@ function InitiativeDetailPage() {
 
   // Single SSE stream for all live updates
   useLiveUpdates([
-    { prefix: 'task:',    invalidate: ['listPhases', 'listTasks', 'listInitiativeTasks'] },
-    { prefix: 'phase:',   invalidate: ['listPhases', 'listTasks', 'listInitiativePhaseDependencies'] },
-    { prefix: 'agent:',   invalidate: ['listAgents', 'getActiveRefineAgent'] },
-    { prefix: 'page:',    invalidate: ['listPages', 'getPage', 'getRootPage'] },
-    { prefix: 'preview:', invalidate: ['listPreviews', 'getPreviewStatus'] },
+    { prefix: 'task:',      invalidate: ['listPhases', 'listTasks', 'listInitiativeTasks', 'getPhaseDependencies', 'listPhaseTaskDependencies'] },
+    { prefix: 'phase:',     invalidate: ['listPhases', 'listTasks', 'listInitiativePhaseDependencies', 'getPhaseDependencies'] },
+    { prefix: 'agent:',     invalidate: ['listAgents', 'getActiveRefineAgent'] },
+    { prefix: 'page:',      invalidate: ['listPages', 'getPage', 'getRootPage'] },
+    { prefix: 'changeset:', invalidate: ['getChangeSet', 'listChangeSets'] },
+    { prefix: 'preview:',   invalidate: ['listPreviews', 'getPreviewStatus'] },
   ]);
 
   // tRPC queries