diff --git a/src/plugin-sdk/config-runtime.ts b/src/plugin-sdk/config-runtime.ts
index abc13e0da0fb..c8a2bb675d5d 100644
--- a/src/plugin-sdk/config-runtime.ts
+++ b/src/plugin-sdk/config-runtime.ts
@@ -8,6 +8,7 @@ import { loadSessionStore as loadSessionStoreImpl } from "../config/sessions/sto
 export {
   getSessionEntry,
   listSessionEntries,
+  patchSessionEntry,
   updateSessionStoreEntry,
   upsertSessionEntry,
 } from "./session-store-runtime.js";
@@ -147,7 +148,6 @@ export type {
 } from "../config/types.js";
 export {
   clearSessionStoreCacheForTest,
-  patchSessionEntry,
   readSessionUpdatedAt,
   recordSessionMetaFromInbound,
   saveSessionStore,
diff --git a/src/plugin-sdk/session-store-runtime.test.ts b/src/plugin-sdk/session-store-runtime.test.ts
index fc3b670bf5af..12c62a012708 100644
--- a/src/plugin-sdk/session-store-runtime.test.ts
+++ b/src/plugin-sdk/session-store-runtime.test.ts
@@ -5,6 +5,7 @@ import { afterEach, beforeEach, describe, expect, it } from "vitest";
 import {
   getSessionEntry,
   listSessionEntries,
+  patchSessionEntry,
   updateSessionStoreEntry,
   upsertSessionEntry,
 } from "./session-store-runtime.js";
@@ -80,6 +81,19 @@ describe("session-store-runtime compatibility surface", () => {
         updatedAt: 10,
       },
     });
+    const beforePatch = getSessionEntry({ sessionKey, storePath });
+    await expect(
+      patchSessionEntry({
+        sessionKey,
+        storePath,
+        preserveActivity: true,
+        update: () => ({ providerOverride: "openai", updatedAt: 20 }),
+      }),
+    ).resolves.toMatchObject({
+      providerOverride: "openai",
+      sessionId: "session-1",
+      updatedAt: beforePatch?.updatedAt,
+    });
     await expect(
       updateSessionStoreEntry({
         sessionKey,
diff --git a/src/plugin-sdk/session-store-runtime.ts b/src/plugin-sdk/session-store-runtime.ts
index f225557a4da9..505ecfe0e4b9 100644
--- a/src/plugin-sdk/session-store-runtime.ts
+++ b/src/plugin-sdk/session-store-runtime.ts
@@ -3,6 +3,7 @@
 import {
   listSessionEntries as listAccessorSessionEntries,
   loadSessionEntry,
+  patchSessionEntry as patchAccessorSessionEntry,
   replaceSessionEntry,
   updateSessionEntry,
 } from "../config/sessions/session-accessor.js";
@@ -28,6 +29,18 @@ type SessionStoreEntryUpdate = (
   entry: SessionEntry,
 ) => Promise<Partial<SessionEntry> | null> | Partial<SessionEntry> | null;
 
+type SessionStoreEntryPatch = (
+  entry: SessionEntry,
+  context: { existingEntry?: SessionEntry },
+) => Promise<Partial<SessionEntry> | null> | Partial<SessionEntry> | null;
+
+type PatchSessionEntryParams = SessionStoreReadParams & {
+  fallbackEntry?: SessionEntry;
+  preserveActivity?: boolean;
+  replaceEntry?: boolean;
+  update: SessionStoreEntryPatch;
+};
+
 type UpdateSessionStoreEntryParams = {
   storePath: string;
   sessionKey: string;
@@ -70,6 +83,27 @@ export function listSessionEntries(
   });
 }
 
+/** Patches one session entry through the accessor seam. */
+export async function patchSessionEntry(
+  params: PatchSessionEntryParams,
+): Promise<SessionEntry | null> {
+  return await patchAccessorSessionEntry(
+    {
+      agentId: params.agentId,
+      env: params.env,
+      hydrateSkillPromptRefs: params.hydrateSkillPromptRefs,
+      sessionKey: params.sessionKey,
+      storePath: params.storePath,
+    },
+    params.update,
+    {
+      fallbackEntry: params.fallbackEntry,
+      preserveActivity: params.preserveActivity,
+      replaceEntry: params.replaceEntry,
+    },
+  );
+}
+
 /** Updates an existing session entry through the accessor seam. */
 export async function updateSessionStoreEntry(
   params: UpdateSessionStoreEntryParams,
@@ -114,7 +148,6 @@ export { resolveGroupSessionKey } from "../config/sessions/group.js";
 export { canonicalizeMainSessionAlias } from "../config/sessions/main-session.js";
 export {
   clearSessionStoreCacheForTest,
-  patchSessionEntry,
   readSessionUpdatedAt,
   recordSessionMetaFromInbound,
   saveSessionStore,
diff --git a/src/plugins/runtime/runtime-agent.ts b/src/plugins/runtime/runtime-agent.ts
index 8777eba0bc6b..0462e128b390 100644
--- a/src/plugins/runtime/runtime-agent.ts
+++ b/src/plugins/runtime/runtime-agent.ts
@@ -13,12 +13,12 @@ import { resolveSessionFilePath, resolveStorePath } from "../../config/sessions/
 import {
   listSessionEntries as listAccessorSessionEntries,
   loadSessionEntry,
+  patchSessionEntry as patchAccessorSessionEntry,
   replaceSessionEntry,
   updateSessionEntry,
 } from "../../config/sessions/session-accessor.js";
 import {
   loadSessionStore,
-  patchSessionEntry,
   saveSessionStore,
   updateSessionStore,
 } from "../../config/sessions/store.js";
@@ -52,6 +52,16 @@ type RuntimeSessionStoreEntryUpdateParams = {
   takeCacheOwnership?: boolean;
 };
 
+type RuntimeSessionStoreEntryPatchParams = RuntimeSessionStoreReadParams & {
+  fallbackEntry?: SessionEntry;
+  preserveActivity?: boolean;
+  replaceEntry?: boolean;
+  update: (
+    entry: SessionEntry,
+    context: { existingEntry?: SessionEntry },
+  ) => Promise<Partial<SessionEntry> | null> | Partial<SessionEntry> | null;
+};
+
 type RuntimeUpsertSessionEntryParams = RuntimeSessionStoreReadParams & {
   entry: SessionEntry;
 };
@@ -91,6 +101,26 @@ function listSessionEntries(
   });
 }
 
+async function patchSessionEntry(
+  params: RuntimeSessionStoreEntryPatchParams,
+): Promise<SessionEntry | null> {
+  return await patchAccessorSessionEntry(
+    {
+      agentId: params.agentId,
+      env: params.env,
+      hydrateSkillPromptRefs: params.hydrateSkillPromptRefs,
+      sessionKey: params.sessionKey,
+      storePath: params.storePath,
+    },
+    params.update,
+    {
+      fallbackEntry: params.fallbackEntry,
+      preserveActivity: params.preserveActivity,
+      replaceEntry: params.replaceEntry,
+    },
+  );
+}
+
 async function updateSessionStoreEntry(
   params: RuntimeSessionStoreEntryUpdateParams,
 ): Promise<SessionEntry | null> {
diff --git a/src/plugins/runtime/types-core.ts b/src/plugins/runtime/types-core.ts
index cfa4cd152d3f..aa9307c2c83e 100644
--- a/src/plugins/runtime/types-core.ts
+++ b/src/plugins/runtime/types-core.ts
@@ -222,7 +222,23 @@ export type PluginRuntimeCore = {
         sessionKey: string;
         entry: import("../../config/sessions/types.js").SessionEntry;
       }>;
-      patchSessionEntry: typeof import("../../config/sessions/store.js").patchSessionEntry;
+      patchSessionEntry: (params: {
+        agentId?: string;
+        env?: NodeJS.ProcessEnv;
+        fallbackEntry?: import("../../config/sessions/types.js").SessionEntry;
+        hydrateSkillPromptRefs?: boolean;
+        preserveActivity?: boolean;
+        replaceEntry?: boolean;
+        sessionKey: string;
+        storePath?: string;
+        update: (
+          entry: import("../../config/sessions/types.js").SessionEntry,
+          context: { existingEntry?: import("../../config/sessions/types.js").SessionEntry },
+        ) =>
+          | Promise<Partial<import("../../config/sessions/types.js").SessionEntry> | null>
+          | Partial<import("../../config/sessions/types.js").SessionEntry>
+          | null;
+      }) => Promise<import("../../config/sessions/types.js").SessionEntry | null>;
       upsertSessionEntry: (params: {
         agentId?: string;
         env?: NodeJS.ProcessEnv;