diff --git a/packages/session-query/session-query/src/observation.ts b/packages/session-query/session-query/src/observation.ts
index 8c08108775..69ddf1f19c 100644
--- a/packages/session-query/session-query/src/observation.ts
+++ b/packages/session-query/session-query/src/observation.ts
@@ -54,8 +54,8 @@ export interface SessionObservationOptions {
  * instance still reports the same revision.
  */
 interface PreparedEntry {
-  /** The persistence instance whose `stat` produced {@link revision}; revisions from another instance are incomparable. */
-  readonly persistence: SessionPersistence
+  /** Stable service identity whose `stat` produced this revision; proxy references are not instance identities. */
+  readonly persistenceIdentity: symbol
   /** Durable revision observed by `stat` immediately before the log read. */
   readonly revision: SessionPersistenceRevision
   /** Unpublished Session restored from the balanced log; never entered into the store. */
@@ -109,7 +109,7 @@ export class SessionObservationReader {
       const snapshot = await this.statSource(persistence, sessionId, signal)
       const attachedDuringStat = this.ctx.sessions.get(sessionId)
       if (attachedDuringStat !== undefined) return this.live(attachedDuringStat, projectionMode)
-      let entry = this.cachedEntry(persistence, sessionId, snapshot.revision)
+      let entry = this.cachedEntry(persistence.identity, sessionId, snapshot.revision)
       if (entry === undefined) {
         const loaded = await this.loadSource(persistence, sessionId, signal)
         throwIfObservationAborted(signal)
@@ -138,7 +138,7 @@ export class SessionObservationReader {
           )
         }
         entry = {
-          persistence,
+          persistenceIdentity: persistence.identity,
           revision: snapshot.revision,
           session,
           events: Object.freeze(seed),
@@ -201,12 +201,12 @@ export class SessionObservationReader {
 
   /** Return a still-valid cached entry and mark it most recently used. */
   private cachedEntry(
-    persistence: SessionPersistence,
+    persistenceIdentity: symbol,
     sessionId: SessionId,
     revision: SessionPersistenceRevision,
   ): PreparedEntry | undefined {
     const cached = this.cache.get(sessionId)
-    if (cached === undefined || cached.persistence !== persistence || cached.revision !== revision) {
+    if (cached === undefined || cached.persistenceIdentity !== persistenceIdentity || cached.revision !== revision) {
       return undefined
     }
     this.cache.delete(sessionId)
diff --git a/packages/session/session-persistence/src/index.ts b/packages/session/session-persistence/src/index.ts
index f17ec2e777..2894aa5f3d 100644
--- a/packages/session/session-persistence/src/index.ts
+++ b/packages/session/session-persistence/src/index.ts
@@ -133,6 +133,9 @@ declare module '@deepseek-ai/cordis' {
  * on this backend instance observe at least that prefix.
  */
 export abstract class SessionPersistence extends Service {
+  /** Process-local instance identity, stable through Context proxies and distinct after service replacement. */
+  readonly identity = Symbol('sessionPersistence')
+
   constructor(ctx: Context) {
     super(ctx, 'sessionPersistence')
   }