diff --git a/.agents/rules/README.md b/.agents/rules/README.md
index 2493e41..1089382 100644
--- a/.agents/rules/README.md
+++ b/.agents/rules/README.md
@@ -12,9 +12,12 @@
   service.
 - Do not consume alternate event/history services or Host-private transport
   contracts. `ctx.agents` owns create/resume/get and returns live Agent handles.
-- Agent Trace consumes only `@cordisx/protocol/sessions/v1` and is honestly
-  unavailable when the Host service, exact route permission, or subscription
-  is unavailable or replaced.
+- Agent Trace consumes `@cordisx/protocol/sessions/v1` plus only the
+  `EntityDefinitionBoundSessionEvent` extension from
+  `@cordisx/protocol/entities/v1`. It never queries `ctx.entities` or relabels
+  Session history from a mutable current registry. It is honestly unavailable
+  when the Host service, exact route permission, or subscription is unavailable
+  or replaced.
 - Every Session capability must be optional and dynamically bound by the Host
   to the active same-plugin route's exact `:sessionId`; never use an empty or
   wildcard scope.
diff --git a/README.md b/README.md
index 03c569a..e0f0287 100644
--- a/README.md
+++ b/README.md
@@ -21,11 +21,17 @@ The Agent/Session Runtime ownership model is:
 - environment composition and transport bindings remain Host-private and do
   not change plugin contracts, permissions, or Session facts.
 
-The contract is `@cordisx/protocol/sessions/v1` at Protocol main commit
-`8891722a7735a3bd00bdd5315084b35b748f5e7f`. The Timeline reads a fixed
-Session snapshot, pages through its immutable watermark, then follows the
-atomic replay/live subscription. Subscription termination clears the view and
-reports the terminal code.
+The contracts are `@cordisx/protocol/sessions/v1` and the additive
+`EntityDefinitionBoundSessionEvent` from `@cordisx/protocol/entities/v1` at
+Protocol main commit `c96c290697f9e802a68c6d3bb094fd27d8d00d1e`.
+The Timeline reads a fixed Session snapshot, pages through its immutable
+watermark, then follows the atomic replay/live subscription. Subscription
+termination clears the view and reports the terminal code.
+
+For an entity-backed Session, `entity/definition-bound` is the durable source
+of the exact historical definition identity, digest, and definition bytes.
+The Timeline projects that persisted binding and never queries `ctx.entities`
+or relabels prior Session history from the latest local entity revision.
 
 The plugin consumes no alternate event service, Host-private import, unsafe
 cast, raw bridge, adapter, or second ledger.
@@ -68,6 +74,7 @@ npm run check
 `npm run check` runs typecheck, build, focused tests, and
 `npm pack --dry-run`. `cordisx.plugin.json` is the immutable package manifest.
 The Protocol dependency is pinned to an exact remotely resolvable main commit.
-The Host runtime is formally available at CordisX main commit
-`d11df2e0d4a2557dc184f4fcec0b7cd8659e289b`. The package remains private until
-real-App integration verification is complete.
+The entity-backed Host runtime is formally available at CordisX main commit
+`ff9cf8b1ba4e4caffa23abbd767dbba0b8884c8a`; Chatroom's entity-backed consumer
+is at `dc1d672b93e6b6a3a29961561546957d66955a1a`. The package remains private
+until real-App integration verification is complete.
diff --git a/README.zh-Hans.md b/README.zh-Hans.md
index f08638d..9f9580b 100644
--- a/README.zh-Hans.md
+++ b/README.zh-Hans.md
@@ -20,11 +20,18 @@ Agent/Session Runtime 的 ownership model 如下：
   Session 事实。
 
 正式契约是 Protocol main commit
-`8891722a7735a3bd00bdd5315084b35b748f5e7f` 的
-`@cordisx/protocol/sessions/v1`。Timeline 先读取固定 Session snapshot，
+`c96c290697f9e802a68c6d3bb094fd27d8d00d1e` 的
+`@cordisx/protocol/sessions/v1`，以及
+`@cordisx/protocol/entities/v1` 中增量定义的
+`EntityDefinitionBoundSessionEvent`。Timeline 先读取固定 Session snapshot，
 分页读取 immutable watermark，再接续 atomic replay/live subscription；订阅
 终止时会清空视图并报告 terminal code。
 
+对 entity-backed Session，`entity/definition-bound` 是历史定义 identity、
+digest 与 definition bytes 的唯一持久事实。Timeline 只投影该 Session 事件中
+持久化的 binding，绝不查询 `ctx.entities`，也不按最新 local entity revision
+重标历史。
+
 插件不消费替代 event service，也不使用 Host-private import、unsafe cast、
 raw bridge、额外 adapter 或第二 ledger。
 
@@ -54,6 +61,7 @@ npm run check
 
 `npm run check` 包含 typecheck、build、focused tests 与
 `npm pack --dry-run`。Protocol dependency 精确 pin 到可从远端解析的 main
-commit。Host Runtime 已在 CordisX main commit
-`d11df2e0d4a2557dc184f4fcec0b7cd8659e289b` 正式提供；真实 App 集成验证闭合前，
-package 保持 private。
+commit。entity-backed Host Runtime 已在 CordisX main commit
+`ff9cf8b1ba4e4caffa23abbd767dbba0b8884c8a` 正式提供；Chatroom 的 entity-backed
+消费已在 main commit `dc1d672b93e6b6a3a29961561546957d66955a1a`
+落地。真实 App 集成验证闭合前，package 保持 private。
diff --git a/cordisx.plugin.json b/cordisx.plugin.json
index f6b9756..c02b053 100644
--- a/cordisx.plugin.json
+++ b/cordisx.plugin.json
@@ -20,7 +20,8 @@
       "https://raw.githubusercontent.com/cordisx/cordisx-protocol/main/schemas/session-snapshot.v1.schema.json",
       "https://raw.githubusercontent.com/cordisx/cordisx-protocol/main/schemas/session-subscribe-request.v1.schema.json",
       "https://raw.githubusercontent.com/cordisx/cordisx-protocol/main/schemas/session-subscription-page.v1.schema.json",
-      "https://raw.githubusercontent.com/cordisx/cordisx-protocol/main/schemas/session-subscription-close.v1.schema.json"
+      "https://raw.githubusercontent.com/cordisx/cordisx-protocol/main/schemas/session-subscription-close.v1.schema.json",
+      "https://raw.githubusercontent.com/cordisx/cordisx-protocol/main/schemas/entity-session-definition-binding.v1.schema.json"
     ]
   },
   "dependencies": [],
diff --git a/docs/MIGRATION-CHECKPOINT.md b/docs/MIGRATION-CHECKPOINT.md
index 1f59503..f1e861f 100644
--- a/docs/MIGRATION-CHECKPOINT.md
+++ b/docs/MIGRATION-CHECKPOINT.md
@@ -50,7 +50,9 @@ This repository currently owns:
 - Host-neutral Timeline model, filtering, grouping, and read-only body view;
 - `TraceShowcaseStore`, which is the read-only Timeline state boundary;
 - `src/session-store.ts`, which consumes only
-  `@cordisx/protocol/sessions/v1`, performs immutable snapshot paging, atomic
+  `@cordisx/protocol/sessions/v1` plus the
+  `EntityDefinitionBoundSessionEvent` extension from
+  `@cordisx/protocol/entities/v1`, performs immutable snapshot paging, atomic
   replay/live subscription, and fail-closed generation/terminal fencing;
 - truthful unavailable state whenever the public Session service or exact
   route-bound permission is absent;
@@ -65,10 +67,12 @@ adapter/ledger, access a raw bridge, or depend on concrete `ctx.agentLoop`.
 Formal Protocol dependency:
 
 - repository: `CordisX/cordisx-protocol`;
-- main commit: `8891722a7735a3bd00bdd5315084b35b748f5e7f`;
+- main commit: `c96c290697f9e802a68c6d3bb094fd27d8d00d1e`;
 - pull requests: `https://github.com/cordisx/cordisx-protocol/pull/77` and
-  `https://github.com/cordisx/cordisx-protocol/pull/78`;
-- public entrypoint: `@cordisx/protocol/sessions/v1`;
+  `https://github.com/cordisx/cordisx-protocol/pull/78`, plus entities/v1
+  `https://github.com/cordisx/cordisx-protocol/pull/79`;
+- public entrypoints: `@cordisx/protocol/sessions/v1` and
+  `@cordisx/protocol/entities/v1`;
 - status: merged to remote main; focused type, conformance, distribution,
   diff, naming, and formal-main export readback passed. The broad Protocol
   workflow retains its pre-existing Manager v2 AJV strict-union failure. Mono
@@ -90,11 +94,11 @@ must never manufacture a durable cursor or ledger.
 Formal Host dependency:
 
 - repository: `CordisX/cordisx`;
-- main commit: `d11df2e0d4a2557dc184f4fcec0b7cd8659e289b`;
+- main commit: `ff9cf8b1ba4e4caffa23abbd767dbba0b8884c8a`;
 - pull requests: `https://github.com/cordisx/cordisx/pull/224` through
-  `https://github.com/cordisx/cordisx/pull/231`;
+  `https://github.com/cordisx/cordisx/pull/236`;
 - status: merged to remote main and pinned to Protocol
-  `8891722a7735a3bd00bdd5315084b35b748f5e7f`; focused Agent/Session runtime,
+  `c96c290697f9e802a68c6d3bb094fd27d8d00d1e`; focused Agent/Session runtime,
   Shell v4 terminal, permission/scope, no-check type, package allowlist, and
   diff checks passed. The #231 composition focus passed 14/14 with CLI
   `tsc --noCheck`. Its broad workflow stopped at
@@ -124,6 +128,29 @@ excluded from filesystem watch/import graphs so Vite cannot reinterpret
 `cordisx/react`, `cordisx/ui`, or JSX-runtime virtual sources as absolute file
 imports; the real transitive source watch graph remains intact.
 
+## ENTITY_DEFINITION_BINDING_READY handoff
+
+Formal entity-backed consumers:
+
+- Host main: `ff9cf8b1ba4e4caffa23abbd767dbba0b8884c8a`
+  (`https://github.com/cordisx/cordisx/pull/236`);
+- Chatroom main: `dc1d672b93e6b6a3a29961561546957d66955a1a`
+  (`https://github.com/cordisx/plugin-chatroom/pull/10`);
+- Protocol main: `c96c290697f9e802a68c6d3bb094fd27d8d00d1e`.
+
+Host persists `entity/definition-bound` as an ignorable SessionEvent when it
+creates an entity-backed Session and resumes only from that persisted binding.
+Chatroom creates against the exact current Entity identity and resumes an
+existing Session with `definitionSource: 'session-persisted'`.
+
+Agent Trace recognizes that one durable extension during the existing
+snapshot/replay/live path. Its projection exposes
+`binding.resolution.identity`, `binding.resolution.digest`, and
+`binding.resolution.definition`. It does not inject or query `ctx.entities`,
+consult Chatroom configuration, or relabel historical runs from a current
+registry snapshot. Other unknown required events still fail closed; unrelated
+extensions remain skippable only when explicitly marked `ignorable: true`.
+
 ## Deferred owner actions
 
 Until real-App integration verification succeeds:
diff --git a/package-lock.json b/package-lock.json
index 2fc0cae..2ee5675 100644
--- a/package-lock.json
+++ b/package-lock.json
@@ -14,7 +14,7 @@
         "cordisx": "0.1.0-beta.1"
       },
       "devDependencies": {
-        "@cordisx/protocol": "github:cordisx/cordisx-protocol#8891722a7735a3bd00bdd5315084b35b748f5e7f",
+        "@cordisx/protocol": "github:cordisx/cordisx-protocol#c96c290697f9e802a68c6d3bb094fd27d8d00d1e",
         "jsdom": "^26.1.0",
         "typescript": "^5.9.2",
         "vitest": "^3.2.4"
@@ -48,8 +48,8 @@
     },
     "node_modules/@cordisx/protocol": {
       "version": "0.1.0-alpha.0",
-      "resolved": "git+ssh://git@github.com/cordisx/cordisx-protocol.git#8891722a7735a3bd00bdd5315084b35b748f5e7f",
-      "integrity": "sha512-y8AYpz29Dgpfo6YXgH7FWUMdApMNH3424PycwHcCIdHtp6AJqL7OyYVJgiWr5Yp4KUdfFbwlFvWAy/dqxeHpKw==",
+      "resolved": "git+ssh://git@github.com/cordisx/cordisx-protocol.git#c96c290697f9e802a68c6d3bb094fd27d8d00d1e",
+      "integrity": "sha512-Q9S3YT30akTq29g3cwe4JRvJ5uRJuNEeOk5Sds8OCjNliOKBnyAewHNmNesN2DQL509sqGX8LZVVFMhnay5j4A==",
       "dev": true,
       "license": "AGPL-3.0-or-later",
       "engines": {
diff --git a/package.json b/package.json
index e710db6..f19136e 100644
--- a/package.json
+++ b/package.json
@@ -29,7 +29,7 @@
     "cordisx": "0.1.0-beta.1"
   },
   "devDependencies": {
-    "@cordisx/protocol": "github:cordisx/cordisx-protocol#8891722a7735a3bd00bdd5315084b35b748f5e7f",
+    "@cordisx/protocol": "github:cordisx/cordisx-protocol#c96c290697f9e802a68c6d3bb094fd27d8d00d1e",
     "jsdom": "^26.1.0",
     "typescript": "^5.9.2",
     "vitest": "^3.2.4"
diff --git a/src/react-view.tsx b/src/react-view.tsx
index d7dad04..503d406 100644
--- a/src/react-view.tsx
+++ b/src/react-view.tsx
@@ -23,11 +23,14 @@ function options(values: readonly string[], all: string) {
 
 function Detail({ event }: { readonly event: TraceEvent | undefined }) {
   if (event === undefined) return <Text tone="muted">Select an event to inspect its public projection.</Text>
+  const definition = event.definitionResolution
   const fields: readonly [string, unknown][] = [
     ['Event', event.id], ['Sequence', event.seq], ['Recorded', event.recordedAt],
     ['Type', event.type], ['Semantic', event.semanticType], ['Phase', event.phase],
     ['Session', event.sessionId], ['Turn', event.turnId], ['Step', event.stepId], ['Item', event.itemId],
     ['Message', event.messageId], ['Tool call', event.toolCallId], ['Context', event.contextId],
+    ['Entity', definition?.identity.agentId], ['Entity revision', definition?.identity.revision],
+    ['Entity digest', definition?.digest], ['Definition name', definition?.definition.name],
     ['Source', `${event.source.kind}:${event.source.id}`],
   ]
   return <><Text as="p"><strong>{event.summary}</strong></Text><dl>{fields.filter(([, value]) => value !== undefined).map(([label, value]) => <Fragment key={label}><dt>{label}</dt><dd>{String(value)}</dd></Fragment>)}</dl>{event.payload === undefined ? null : <pre className="cat-payload">{JSON.stringify(event.payload, null, 2)}</pre>}</>
diff --git a/src/session-store.ts b/src/session-store.ts
index 09d19aa..cd9683c 100644
--- a/src/session-store.ts
+++ b/src/session-store.ts
@@ -10,6 +10,7 @@ import type {
   SessionSubscriptionPage,
   UserMessage,
 } from '@cordisx/protocol/sessions/v1'
+import type { EntityDefinitionResolution } from '@cordisx/protocol/entities/v1'
 import type {
   TraceEvent,
   TraceLane,
@@ -72,6 +73,7 @@ function lifecyclePhase(event: SessionEvent): TracePhase | undefined {
 function lane(event: SessionEvent): TraceLane {
   switch (event.type) {
     case 'user/message': return 'input'
+    case 'entity/definition-bound':
     case 'agent/inbox/spliced': return 'injection'
     case 'tool/call':
     case 'tool/result':
@@ -109,6 +111,10 @@ function summary(event: SessionEvent): string {
     case 'agent/inbox/spliced': return `Agent ${event.data.target} inbox changed.`
     case 'approval/asked': return `Approval requested for ${event.data.toolName}.`
     case 'approval/decided': return `Approval ${event.data.outcome}.`
+    case 'entity/definition-bound': {
+      const { identity, digest, definition } = event.data.resolution
+      return `Session definition bound to ${definition.name ?? identity.agentId} (${identity.agentId}@${identity.revision}; ${digest}).`
+    }
     case 'session/end-seed': return 'Persisted Session seed ended.'
     default: return unknownEvent(event)
   }
@@ -171,6 +177,9 @@ export function projectSessionEvent(event: SessionEvent): TraceEvent | undefined
     : event.type === 'tool/result'
       ? event.data.message.source.callId
       : undefined
+  const definitionResolution: EntityDefinitionResolution | undefined = event.type === 'entity/definition-bound'
+    ? event.data.resolution
+    : undefined
   return Object.freeze({
     id: `session:${event.sessionId}:${event.seq}`,
     sessionId: event.sessionId,
@@ -186,6 +195,7 @@ export function projectSessionEvent(event: SessionEvent): TraceEvent | undefined
     ...(step === undefined ? {} : { stepId: step }),
     ...(messageId === undefined ? {} : { messageId }),
     ...(toolCallId === undefined ? {} : { toolCallId }),
+    ...(definitionResolution === undefined ? {} : { definitionResolution }),
     payload: event.data,
   })
 }
diff --git a/src/types.ts b/src/types.ts
index 98bdc56..955ee06 100644
--- a/src/types.ts
+++ b/src/types.ts
@@ -1,3 +1,5 @@
+import type { EntityDefinitionResolution } from '@cordisx/protocol/entities/v1'
+
 export type TraceLane = 'input' | 'model' | 'tools' | 'injection'
 export type TracePhase =
   | 'opened' | 'resumed' | 'started' | 'updated' | 'completed'
@@ -28,6 +30,7 @@ export interface TraceEvent {
   readonly messageId?: string
   readonly toolCallId?: string
   readonly contextId?: string
+  readonly definitionResolution?: EntityDefinitionResolution
   readonly payload?: unknown
 }
 
diff --git a/test/architecture-guard.test.ts b/test/architecture-guard.test.ts
index d1680cf..10f1c45 100644
--- a/test/architecture-guard.test.ts
+++ b/test/architecture-guard.test.ts
@@ -13,6 +13,7 @@ describe('architecture guard', () => {
       'ctx.agentEvents',
       'ctx.agentHistory',
       'ctx.agentLoop',
+      'ctx.entities',
       'agentEvents',
       'agentHistory',
       'electronBridge',
@@ -23,6 +24,7 @@ describe('architecture guard', () => {
       'getElementById',
       'packages/cli/src',
       'packages/host',
+      'EntityRegistry',
     ]) expect(source).not.toContain(forbidden)
   })
 
diff --git a/test/session-store.test.ts b/test/session-store.test.ts
index 20430db..1741b93 100644
--- a/test/session-store.test.ts
+++ b/test/session-store.test.ts
@@ -10,9 +10,11 @@ import type {
   SessionSubscriptionClosed,
   SessionSubscriptionPage,
 } from '@cordisx/protocol/sessions/v1'
+import type { EntityDefinitionBoundSessionEvent } from '@cordisx/protocol/entities/v1'
 import { SessionTraceStore, projectSessionEvent } from '../src/session-store.js'
 
 const schema = 'https://raw.githubusercontent.com/cordisx/cordisx-protocol/main/schemas/session-event.v1.schema.json' as const
+const persistedDigest = `sha256:${'a'.repeat(64)}` as const
 
 function event(seq: number, type: SessionEvent['type'], data: unknown): SessionEvent {
   return {
@@ -27,6 +29,40 @@ function event(seq: number, type: SessionEvent['type'], data: unknown): SessionE
   } as unknown as SessionEvent
 }
 
+function entityDefinitionBoundEvent(seq: number): EntityDefinitionBoundSessionEvent {
+  const identity = { agentId: 'chatroom.generalist', revision: persistedDigest }
+  return {
+    $schema: schema,
+    contract: 'cordisx.session-event/v1',
+    schemaVersion: 1,
+    sessionId: 'session-a',
+    seq,
+    time: Date.UTC(2026, 0, 1, 0, 0, seq),
+    type: 'entity/definition-bound',
+    ignorable: true,
+    data: {
+      source: 'entity-registry',
+      owner: { profileId: 'profile-a', installationId: 'installation-a', pluginId: 'chatroom' },
+      resolution: {
+        identity,
+        digest: persistedDigest,
+        definition: {
+          $schema: 'https://raw.githubusercontent.com/cordisx/cordisx-protocol/main/schemas/agent-definition.v1.schema.json',
+          contract: 'cordisx.agent-definition/v1',
+          schemaVersion: 1,
+          identity,
+          name: 'Persisted Generalist',
+          inherit: {
+            promptSections: 'none', rules: 'none', skills: 'none',
+            tools: 'none', mcpServers: 'none', runtimeDefaults: 'none',
+          },
+          promptSections: [{ sectionId: 'role', kind: 'role', text: 'Persisted role bytes.' }],
+        },
+      },
+    },
+  }
+}
+
 function page(afterSeq: number, snapshotSeq: number, events: readonly SessionEvent[]): SessionEventPage {
   const nextAfterSeq = events.at(-1)?.seq ?? afterSeq
   return {
@@ -166,6 +202,33 @@ describe('SessionTraceStore', () => {
     expect(harness.unsubscribe).toHaveBeenCalledOnce()
   })
 
+  it('carries the persisted entity binding through the same snapshot, replay, and live cursor path', async () => {
+    const harness = sessionHarness({
+      snapshotSeq: 0,
+      pages: [page(-1, 0, [entityDefinitionBoundEvent(0)])],
+      replay: [event(1, 'turn/start', { turn: 1 })],
+    })
+    const store = new SessionTraceStore(harness.sessions, 'session-a', 50)
+    await store.settled()
+
+    expect(store.getSnapshot().events.map(item => item.type)).toEqual([
+      'entity/definition-bound',
+      'turn/start',
+    ])
+    expect(store.getSnapshot().events[0]?.definitionResolution?.definition.name).toBe('Persisted Generalist')
+
+    await harness.observer()!(subscriptionPage('live', 1, [
+      event(2, 'user/message', {
+        id: 'message-user', role: 'user', content: [{ type: 'text', text: 'Continue' }], source: { kind: 'user' },
+      }),
+    ]))
+    expect(store.getSnapshot()).toMatchObject({
+      events: [{ type: 'entity/definition-bound' }, { type: 'turn/start' }, { type: 'user/message' }],
+      range: { totalAvailable: 3 },
+    })
+    store.dispose()
+  })
+
   it('fails closed and clears rows on a sequence or generation fence violation', async () => {
     const harness = sessionHarness({
       snapshotSeq: 1,
@@ -245,6 +308,29 @@ describe('SessionTraceStore', () => {
 })
 
 describe('SessionEvent projection', () => {
+  it('attributes entity-backed history only to the Session-persisted definition binding', () => {
+    const projected = projectSessionEvent(entityDefinitionBoundEvent(0))
+
+    expect(projected).toMatchObject({
+      type: 'entity/definition-bound',
+      lane: 'injection',
+      definitionResolution: {
+        identity: { agentId: 'chatroom.generalist', revision: persistedDigest },
+        digest: persistedDigest,
+        definition: {
+          name: 'Persisted Generalist',
+          promptSections: [{ text: 'Persisted role bytes.' }],
+        },
+      },
+      payload: {
+        source: 'entity-registry',
+        resolution: { identity: { agentId: 'chatroom.generalist', revision: persistedDigest } },
+      },
+    })
+    expect(projected?.summary).toContain(`chatroom.generalist@${persistedDigest}`)
+    expect(projected?.summary).not.toContain('Latest local revision')
+  })
+
   it('projects every durable core variant from the formal v1 vocabulary', () => {
     const variants: readonly [SessionEvent['type'], unknown][] = [
       ['turn/start', { turn: 1 }],
diff --git a/test/view.test.tsx b/test/view.test.tsx
index e11393f..d34ce76 100644
--- a/test/view.test.tsx
+++ b/test/view.test.tsx
@@ -5,7 +5,7 @@ import { describe, expect, it, vi } from 'vitest'
 import type { CordisXReactPageProps } from 'cordisx/contracts'
 import { UnavailableTraceStore } from '../src/unavailable-store.js'
 import { createTraceReactPage } from '../src/react-view.js'
-import type { TraceShowcaseStore } from '../src/types.js'
+import type { TraceEvent, TraceShowcaseStore } from '../src/types.js'
 
 vi.mock('cordisx/ui', async () => {
   const React = await import('react')
@@ -86,6 +86,20 @@ function availableStore(): TraceShowcaseStore {
   }
 }
 
+function eventStore(event: TraceEvent): TraceShowcaseStore {
+  const baseline = availableStore().getSnapshot()
+  const snapshot = Object.freeze({
+    ...baseline,
+    events: Object.freeze([event]),
+    range: Object.freeze({ loaded: 1, totalAvailable: 1, renderedLimit: 100 }),
+  })
+  return {
+    getSnapshot: () => snapshot,
+    subscribe: () => () => {},
+    dispose: () => {},
+  }
+}
+
 describe('Host-owned Agent Trace body', () => {
   it('renders SessionEvent rows, detail, and no Host chrome', async () => {
     const dom = new JSDOM('<body><div id="root"></div></body>')
@@ -116,6 +130,41 @@ describe('Host-owned Agent Trace body', () => {
     root.unmount()
   })
 
+  it('shows the Session-persisted entity identity, digest, and definition', async () => {
+    const dom = new JSDOM('<body><div id="root"></div></body>')
+    const digest = `sha256:${'a'.repeat(64)}` as const
+    const identity = { agentId: 'chatroom.generalist', revision: digest }
+    const store = eventStore(Object.freeze({
+      id: 'session:session-a:0', sessionId: 'session-a', seq: 0,
+      recordedAt: '2026-01-01T00:00:00.000Z', lane: 'injection',
+      type: 'entity/definition-bound', semanticType: 'entity/definition-bound',
+      summary: 'Session definition bound to Persisted Generalist.',
+      source: Object.freeze({ kind: 'session', id: 'session-a', label: 'Host Session authority' }),
+      definitionResolution: {
+        identity,
+        digest,
+        definition: {
+          $schema: 'https://raw.githubusercontent.com/cordisx/cordisx-protocol/main/schemas/agent-definition.v1.schema.json',
+          contract: 'cordisx.agent-definition/v1', schemaVersion: 1,
+          identity, name: 'Persisted Generalist',
+          inherit: {
+            promptSections: 'none', rules: 'none', skills: 'none',
+            tools: 'none', mcpServers: 'none', runtimeDefaults: 'none',
+          },
+        },
+      },
+    }))
+    const root = await mount(dom, store)
+
+    dom.window.document.querySelector<HTMLTableRowElement>('.cat-row')!.click()
+    await new Promise(resolve => setTimeout(resolve, 20))
+    const detail = dom.window.document.querySelector('.cat-detail')?.textContent
+    expect(detail).toContain('chatroom.generalist')
+    expect(detail).toContain(digest)
+    expect(detail).toContain('Persisted Generalist')
+    root.unmount()
+  })
+
   it('disposes the prior Session store when the Host route replaces sessionId', async () => {
     const dom = new JSDOM('<body><div id="root"></div></body>')
     Object.defineProperty(globalThis, 'window', { configurable: true, value: dom.window })