diff --git a/apps/server/src/orchestration-v2/Orchestrator.ts b/apps/server/src/orchestration-v2/Orchestrator.ts
index 0756fdd59cdafe8767f2b9c123455f73bfb84e62..6853c6457d6d021335ca655157b53fa9f23c0d38 100644
--- a/apps/server/src/orchestration-v2/Orchestrator.ts
+++ b/apps/server/src/orchestration-v2/Orchestrator.ts
@@ -3251,6 +3251,27 @@ const makeOrchestrator = Effect.fn("orchestrationV2.Orchestrator.layer")(functio
           };
       }
     })();
+    if (
+      command.type === "thread.pull-request-link.sync" ||
+      command.type === "thread.pull-request-watch.sync"
+    ) {
+      if (updatedThread === thread) return;
+      const link = threadPullRequestsOf(updatedThread).find((candidate) =>
+        threadPullRequestKeysEqual(candidate, normalizeThreadPullRequestKey(command)),
+      );
+      if (link === undefined) return;
+      yield* emit(
+        events,
+        command,
+      )({
+        type: "thread.pull-request-link-updated",
+        threadId: command.threadId,
+        providerInstanceId: updatedThread.providerInstanceId,
+        occurredAt: now,
+        payload: link,
+      });
+      return;
+    }
     const eventType = (() => {
       switch (command.type) {
         case "thread.archive":
@@ -3282,9 +3303,7 @@ const makeOrchestrator = Effect.fn("orchestrationV2.Orchestrator.layer")(functio
           return "thread.metadata-updated" as const;
         case "thread.pull-request.link":
         case "thread.pull-request.unlink":
-        case "thread.pull-request-link.sync":
         case "thread.pull-request.watch":
-        case "thread.pull-request-watch.sync":
         case "thread.pull-request.sync":
           return "thread.pull-request-synced" as const;
         case "thread.runtime-mode.set":
diff --git a/apps/server/src/orchestration-v2/ProjectionStore.ts b/apps/server/src/orchestration-v2/ProjectionStore.ts
index f3348438352703cb915ede612937c048ee776eeb..b999f6376ecb3fdc539dc24de46653adaa28d6bd 100644
--- a/apps/server/src/orchestration-v2/ProjectionStore.ts
+++ b/apps/server/src/orchestration-v2/ProjectionStore.ts
@@ -1,3 +1,4 @@
+import { applyThreadPullRequestLinkUpdate } from "@t3tools/shared/threadPullRequests";
 import { projectTurnItemForWire } from "./WireProjection.ts";
 import * as Stream from "effect/Stream";
 import { makeThreadFind, findProjectedThreadItems } from "./ThreadFind.ts";
@@ -718,6 +719,11 @@ export function applyToProjection(
   };
 
   switch (event.type) {
+    case "thread.pull-request-link-updated":
+      return {
+        ...base,
+        thread: applyThreadPullRequestLinkUpdate(projection.thread, event.payload),
+      };
     case "thread.created":
     case "thread.archived":
     case "thread.unarchived":
@@ -1823,6 +1829,15 @@ export const layer: Layer.Layer<ProjectionStoreV2, never, SqlClient.SqlClient> =
     const apply: ProjectionStoreV2Shape["apply"] = (event) =>
       Effect.gen(function* () {
         switch (event.type) {
+          case "thread.pull-request-link-updated": {
+            const thread = yield* getThread(event.threadId);
+            yield* apply({
+              ...event,
+              type: "thread.pull-request-synced",
+              payload: applyThreadPullRequestLinkUpdate(thread, event.payload),
+            });
+            break;
+          }
           case "thread.created":
           case "thread.archived":
           case "thread.unarchived":
diff --git a/apps/server/src/orchestration-v2/PullRequestSyncReactor.ts b/apps/server/src/orchestration-v2/PullRequestSyncReactor.ts
index b1fe998c229608a49519a5d3c3e56d9e32203022..70be6e0b08780b0d9e6fd3df53c62883093541c4 100644
--- a/apps/server/src/orchestration-v2/PullRequestSyncReactor.ts
+++ b/apps/server/src/orchestration-v2/PullRequestSyncReactor.ts
@@ -440,6 +440,8 @@ export const make = Effect.gen(function* () {
     yield* forkParked(
       Stream.runForEach(events, (event) => {
         switch (event.type) {
+          case "thread.pull-request-link-updated":
+            return event.payload.snapshot === null ? requestSync(event.payload) : Effect.void;
           case "thread.pull-request-synced":
             return Effect.forEach(
               visibleThreadPullRequests(event.payload.pullRequests ?? []).filter(
diff --git a/apps/server/src/orchestration-v2/ThreadSettlementService.ts b/apps/server/src/orchestration-v2/ThreadSettlementService.ts
index 0eb779639116b0fa67d991f047d8637d262159e3..bd7a7fd58dcb01491963e678884b413c8c7ad1ae 100644
--- a/apps/server/src/orchestration-v2/ThreadSettlementService.ts
+++ b/apps/server/src/orchestration-v2/ThreadSettlementService.ts
@@ -606,6 +606,7 @@ export const make = Effect.gen(function* () {
     switch (event.type) {
       case "thread.settled":
         return cleanUpSettledThread(event.threadId);
+      case "thread.pull-request-link-updated":
       case "thread.pull-request-synced":
       case "provider-session.detached":
         return worker.enqueue(event.threadId);
diff --git a/apps/server/src/orchestration-v2/runtimeLayer.test.ts b/apps/server/src/orchestration-v2/runtimeLayer.test.ts
index c4f5b8295fd9c8144920b57b5089482792ab08de..9bd7f38ddb8bb5e7e9d23e371f1157b06e74a59b 100644
--- a/apps/server/src/orchestration-v2/runtimeLayer.test.ts
+++ b/apps/server/src/orchestration-v2/runtimeLayer.test.ts
@@ -4860,6 +4860,93 @@ it.layer(layerSharedApplicationDataPlaneTest)("visited projection", (it) => {
   );
 });
 
+it.layer(Layer.fresh(layerSharedApplicationDataPlaneTest))("compact PR events", (it) => {
+  it.effect("persists only the changed PR link and replays it without losing other links", () =>
+    Effect.gen(function* () {
+      const orchestrator = yield* Orchestrator.OrchestratorV2;
+      const maintenance = yield* ProjectionMaintenance.ProjectionMaintenanceV2;
+      const sql = yield* SqlClient.SqlClient;
+      const threadId = ThreadId.make("compact-pr-sync");
+      yield* orchestrator.dispatch({
+        type: "thread.create",
+        createdBy: "user",
+        creationSource: "web",
+        commandId: CommandId.make("compact-pr-create"),
+        threadId,
+        projectId: ProjectId.make("compact-pr-project"),
+        title: "PR sync",
+        modelSelection,
+        runtimeMode: "full-access",
+        interactionMode: "default",
+        branch: null,
+        worktreePath: null,
+      });
+      const key = { host: "github.com", repository: "pingdotgg/t3code" };
+      for (const number of [1, 2, 3]) {
+        yield* orchestrator.dispatch({
+          type: "thread.pull-request.link",
+          commandId: CommandId.make(`compact-pr-link-${number}`),
+          threadId,
+          ...key,
+          number,
+          url: `https://github.com/pingdotgg/t3code/pull/${number}`,
+          source: "manual",
+        });
+      }
+      const before = yield* orchestrator.getThreadShell(threadId);
+      yield* orchestrator.dispatch({
+        type: "thread.pull-request-link.sync",
+        commandId: CommandId.make("compact-pr-sync"),
+        threadId,
+        ...key,
+        number: 2,
+        snapshot: {
+          state: "open",
+          title: "Updated PR",
+          headBranch: "feature/pr",
+          baseBranch: "main",
+          isDraft: false,
+          updatedAt: null,
+          syncedAt: "2026-10-13T12:00:00.000Z",
+        },
+        stack: {
+          kind: "native",
+          id: "updated",
+          number: 2,
+          url: "https://github.com/pingdotgg/t3code/pull/2",
+          base: "main",
+          layers: [],
+        },
+      });
+      const rows = yield* sql<{ event_type: string; payload_json: string }>`
+        SELECT event_type, payload_json FROM orchestration_events
+        WHERE command_id = ${"compact-pr-sync"}
+      `;
+      assert.equal(rows.length, 1);
+      assert.equal(rows[0]?.event_type, "thread.pull-request-link-updated");
+      const payload = JSON.parse(rows[0]!.payload_json);
+      assert.equal(payload.number, 2);
+      assert.isUndefined(payload.pullRequests);
+      const after = yield* orchestrator.getThreadShell(threadId);
+      assert.equal(after?.pullRequests?.length, 3);
+      assert.deepEqual(after?.pullRequests?.[0], before?.pullRequests?.[0]);
+      assert.deepEqual(after?.pullRequests?.[2], before?.pullRequests?.[2]);
+      assert.equal(after?.pullRequests?.[1]?.stack?.id, "updated");
+      assert.isTrue((yield* maintenance.rebuild).valid);
+      assert.deepEqual(
+        (yield* orchestrator.getThreadShell(threadId))?.pullRequests,
+        after?.pullRequests,
+      );
+      yield* maintenance.compactEventStore;
+      assert.isTrue((yield* maintenance.rebuild).valid);
+      assert.deepEqual(
+        (yield* orchestrator.getThreadShell(threadId))?.pullRequests,
+        after?.pullRequests,
+      );
+    }),
+  );
+});
+
 it.layer(layerSharedApplicationDataPlaneTest)("shared application data plane", (it) => {
   it.effect("orders retained project transactions and V2 thread transactions in one source", () =>
     Effect.gen(function* () {
diff --git a/apps/server/src/relay/AgentAwarenessRelay.ts b/apps/server/src/relay/AgentAwarenessRelay.ts
index 55ddeac252c256ca7433a89e0d1cd8d959a91f82..447192fce47b65aae0e767e6478a33b9710858b6 100644
--- a/apps/server/src/relay/AgentAwarenessRelay.ts
+++ b/apps/server/src/relay/AgentAwarenessRelay.ts
@@ -97,6 +97,7 @@ export function shouldPublishAgentAwarenessEvent(
     case "thread.unarchived":
     case "thread.deleted":
     case "thread.metadata-updated":
+    case "thread.pull-request-link-updated":
     case "thread.pull-request-synced":
     case "thread.model-selection-updated":
     case "thread.provider-switched":
diff --git a/packages/client-runtime/src/state/orchestrationV2Projection.test.ts b/packages/client-runtime/src/state/orchestrationV2Projection.test.ts
index e41eb81257f9aecc03aad5214ef1adc1c9f9dccd..478365a2e5318b4f16e9f1c03045f4b38b31c09c 100644
--- a/packages/client-runtime/src/state/orchestrationV2Projection.test.ts
+++ b/packages/client-runtime/src/state/orchestrationV2Projection.test.ts
@@ -1,5 +1,6 @@
 import { describe, expect, it } from "vite-plus/test";
 import {
+  type ThreadPullRequestLink,
   type OrchestrationV2DomainEvent,
   type OrchestrationV2Run,
   type OrchestrationV2ThreadProjection,
@@ -105,6 +106,34 @@ const emptyProjection = {
 } as OrchestrationV2ThreadProjection;
 
 describe("applyOrchestrationV2ProjectionEvent", () => {
+  it("applies a compact PR sync without replacing other links or thread metadata", () => {
+    const link = (number: number): ThreadPullRequestLink => ({
+      host: "github.com",
+      repository: "pingdotgg/t3code",
+      number,
+      url: `https://github.com/pingdotgg/t3code/pull/${number}`,
+      source: "manual",
+      linkedAt: DateTime.formatIso(now),
+      snapshot: null,
+      stack: null,
+    });
+    const links = [link(1), link(2)];
+    const projection = {
+      ...emptyProjection,
+      thread: { ...emptyProjection.thread, pullRequests: links },
+    };
+    const updated = { ...links[1]!, source: "agent" as const };
+    const next = applyOrchestrationV2ProjectionEvent(projection, {
+      id: "compact-sync" as OrchestrationV2DomainEvent["id"],
+      type: "thread.pull-request-link-updated",
+      threadId,
+      occurredAt: now,
+      payload: updated,
+    });
+    expect(next?.thread).toEqual({ ...projection.thread, pullRequests: [links[0], updated] });
+    expect(next?.thread.pullRequests?.[0]).toBe(links[0]);
+  });
+
   it("keeps live token usage when the terminal provider turn omits it", () => {
     const providerTurnId = ProviderTurnId.make("provider-turn-reducer");
     const running = {
diff --git a/packages/client-runtime/src/state/orchestrationV2Projection.ts b/packages/client-runtime/src/state/orchestrationV2Projection.ts
index 4587221c07dffd059eaac0fc0ddbd4e3aa47ed21..3c9c6dfa79caf3d36f679bd5d37b2c7eb97a7224 100644
--- a/packages/client-runtime/src/state/orchestrationV2Projection.ts
+++ b/packages/client-runtime/src/state/orchestrationV2Projection.ts
@@ -1,3 +1,4 @@
+import { applyThreadPullRequestLinkUpdate } from "@t3tools/shared/threadPullRequests";
 import type {
   OrchestrationV2DomainEvent,
   OrchestrationV2Run,
@@ -201,6 +202,11 @@ export function applyOrchestrationV2ProjectionEvent(
   const latestLocalTurnOrdinal = options?.latestLocalTurnOrdinal;
   const base = { ...projection, updatedAt: event.occurredAt };
   switch (event.type) {
+    case "thread.pull-request-link-updated":
+      return {
+        ...base,
+        thread: applyThreadPullRequestLinkUpdate(projection.thread, event.payload),
+      };
     case "thread.created":
     case "thread.archived":
     case "thread.unarchived":
diff --git a/packages/contracts/src/orchestrationV2.ts b/packages/contracts/src/orchestrationV2.ts
index 41eabae0aea6d77d00790ab1190e400e09c53512..028d536d3758f9220b5d865633f072d81f634f46 100644
--- a/packages/contracts/src/orchestrationV2.ts
+++ b/packages/contracts/src/orchestrationV2.ts
@@ -1765,6 +1765,11 @@ export const OrchestrationV2DomainEvent = Schema.Union([
     ]),
     payload: OrchestrationV2AppThread,
   }),
+  Schema.Struct({
+    ...OrchestrationV2EventBase.fields,
+    type: Schema.Literal("thread.pull-request-link-updated"),
+    payload: ThreadPullRequestLink,
+  }),
   Schema.Struct({
     ...OrchestrationV2EventBase.fields,
     type: Schema.Literal("run.created"),
@@ -2585,6 +2590,11 @@ export const OrchestrationV2DomainEventJson = Schema.Union([
     ]),
     payload: OrchestrationV2AppThreadJson,
   }),
+  Schema.Struct({
+    ...OrchestrationV2JsonEventBaseFields,
+    type: Schema.Literal("thread.pull-request-link-updated"),
+    payload: ThreadPullRequestLink,
+  }),
   Schema.Struct({
     ...OrchestrationV2JsonEventBaseFields,
     type: Schema.Literal("run.created"),
diff --git a/packages/shared/src/threadPullRequests.ts b/packages/shared/src/threadPullRequests.ts
index 97b800d8682ffe4a54d4863a6a99a38ce0a35f50..e926e10d3b43ed8c363bb0341a899b161ba1b205 100644
--- a/packages/shared/src/threadPullRequests.ts
+++ b/packages/shared/src/threadPullRequests.ts
@@ -1,4 +1,5 @@
 import type {
+  OrchestrationV2AppThread,
   RepositoryIdentity,
   SourceControlProviderKind,
   ThreadLinkedPullRequest,
@@ -354,3 +355,16 @@ export function threadPullRequestsOf(thread: {
         },
       ];
 }
+
+/** Apply a single-link sync without copying unrelated PRs into the event history. */
+export function applyThreadPullRequestLinkUpdate(
+  thread: OrchestrationV2AppThread,
+  updated: ThreadPullRequestLink,
+): OrchestrationV2AppThread {
+  return {
+    ...thread,
+    pullRequests: threadPullRequestsOf(thread).map((link) =>
+      threadPullRequestKeysEqual(link, updated) ? updated : link,
+    ),
+  };
+}