diff --git a/apps/web/tests/agent-preset-selection.e2e.ts b/apps/web/tests/agent-preset-selection.e2e.ts
index 49e302c4c3..b153e29dff 100644
--- a/apps/web/tests/agent-preset-selection.e2e.ts
+++ b/apps/web/tests/agent-preset-selection.e2e.ts
@@ -19,6 +19,7 @@ import {
   SESSION_FORMAT_VERSION, SessionId as sessionId, type SessionEvent, type SessionHeader, type SessionId,
 } from '@deepseek-ai/dsh-session'
 import { snapshotSubagentDescriptor } from '@deepseek-ai/dsh-subagent'
+import { createSystemMessage, createUserMessage } from '@deepseek-ai/dsh-llm'
 import {
   captureStableAria, compareOrRefreshGolden, launchWebScaffold, seedSession, watchConsole,
   webSnapshotMode, type WebScaffold,
@@ -81,7 +82,8 @@ async function seedWorkspaceSkill(workspaceCwd: string): Promise<void> {
 /**
  * A settled one-turn session with no model content: this lane asserts chrome
  * around a conversation, not a conversation, and a recorded turn would tie
- * the golden to a provider's wording for no gain.
+ * the golden to a provider's wording for no gain. Its empty system head
+ * belongs to the first step, before the user message.
  * @returns a tokenized session log ending on a closed turn.
  */
 function seedLog(): string {
@@ -89,9 +91,18 @@ function seedLog(): string {
   const at = (index: number, event: Record<string, unknown>): string =>
     JSON.stringify({ ...event, seq: index, time: time + index })
   return [
-    JSON.stringify({ type: 'session', version: 0, id: '{{sessionId}}', createdAt: time, cwd: '{{cwd}}/workspace' }),
+    JSON.stringify({
+      type: 'session', version: SESSION_FORMAT_VERSION, id: '{{sessionId}}',
+      createdAt: time, cwd: '{{cwd}}/workspace', isSeeded: false, delegationDepth: 0,
+    }),
     at(0, { type: 'turn/start', data: { turn: 1, trigger: { kind: 'message', source: { kind: 'user', rpcId: 'seed' } } } }),
-    at(1, {
+    at(1, { type: 'step/start', data: { turn: 1, step: 1 } }),
+    at(2, {
+      type: 'system/message',
+      data: { turn: 1, step: 1, message: createSystemMessage('', '@deepseek-ai/dsh-system-prompt') },
+      surfaceOp: 'append',
+    }),
+    at(3, {
       type: 'user/message',
       data: {
         id: '00000000-0000-4000-9000-000000000001',
@@ -101,8 +112,9 @@ function seedLog(): string {
       },
       surfaceOp: 'append',
     }),
-    at(2, { type: 'session/title', data: { title: 'Seeded turn', messageSeqs: [1], source: { kind: 'fallback' } } }),
-    at(3, { type: 'turn/end', data: { turn: 1, reason: { kind: 'completed' } } }),
+    at(4, { type: 'session/title', data: { title: 'Seeded turn', messageSeqs: [3], source: { kind: 'fallback' } } }),
+    at(5, { type: 'step/end', data: { turn: 1, step: 1 } }),
+    at(6, { type: 'turn/end', data: { turn: 1, reason: { kind: 'completed' } } }),
   ].join('\n')
 }
 
@@ -138,10 +150,10 @@ async function seedSubagent(scaffold: WebScaffold, parentId: SessionId): Promise
       type: 'user/message',
       seq: 1,
       time: createdAt + 1,
-      data: {
+      data: createUserMessage({
         content: [{ type: 'text', text: 'Check the session-header action order.' }],
         source: { kind: 'user' },
-      },
+      }),
       surfaceOp: 'append',
     },
     {
diff --git a/apps/web/tests/stats-paged-history.e2e.ts b/apps/web/tests/stats-paged-history.e2e.ts
index 6e6174232c..18e2b06edc 100644
--- a/apps/web/tests/stats-paged-history.e2e.ts
+++ b/apps/web/tests/stats-paged-history.e2e.ts
@@ -1,5 +1,5 @@
 // Web e2e scenario: full-session stats over paged history. A deterministic
-// 28-turn log (56 surface messages — more than one 50-message history page)
+// 28-turn log (56 chat messages — more than one 50-message history page)
 // seeded cold through the REAL persistence API must render whole-log turn/step
 // counts from the sessionStats projection on first open, and loading the
 // older page must NOT change them. This pins the bug the projection fixed:
@@ -9,6 +9,8 @@
 import { fileURLToPath } from 'node:url'
 import type { Browser, Page } from 'playwright'
 import { chromium } from 'playwright'
+import { createSystemMessage } from '@deepseek-ai/dsh-llm'
+import { SESSION_FORMAT_VERSION } from '@deepseek-ai/dsh-session'
 import { afterAll, beforeAll, describe, expect, it, onTestFailed } from 'vitest'
 import {
   assertFixtureInventory, captureStableAria, compareOrRefreshGolden,
@@ -21,20 +23,21 @@ const UI_EXPECTED = fileURLToPath(new URL('./expected/stats-paged-history/ui.exp
 const MODE = webSnapshotMode()
 const SEED_ID = 'stats-paged-history-web-e2e'
 
-/** Turn count: 2 surface messages per turn, so 28 turns overflow one 50-message page. */
+/** Turn count: 2 chat messages per turn, so 28 turns overflow one 50-message page. */
 const TURNS = 28
 const FULL_COUNTS = `${TURNS} turns · ${TURNS} steps`
 
 /**
  * Generate the seed: TURNS closed single-step turns of one short user prompt
- * and one short assistant reply each. Times are fixed so the fixture is
- * byte-deterministic; message ids are synthetic uuids (aria normalizes them).
+ * and one short assistant reply each. Fixed times pin displayed dates;
+ * the empty system head precedes every user message in the current format.
  * @param turns - closed turns to generate.
  * @returns session.jsonl text for {@link seedSession}.
  */
 function buildSeed(turns: number): string {
   const lines = [JSON.stringify({
-    type: 'session', version: 0, id: '{{sessionId}}', createdAt: 1784974100000, cwd: '{{cwd}}/workspace',
+    type: 'session', version: SESSION_FORMAT_VERSION, id: '{{sessionId}}',
+    createdAt: 1784974100000, cwd: '{{cwd}}/workspace', isSeeded: false, delegationDepth: 0,
   })]
   let seq = 0
   let time = 1784974100000
@@ -43,6 +46,14 @@ function buildSeed(turns: number): string {
   }
   for (let turn = 1; turn <= turns; turn++) {
     at({ type: 'turn/start', data: { turn } })
+    at({ type: 'step/start', data: { turn, step: 1 } })
+    if (turn === 1) {
+      at({
+        type: 'system/message',
+        data: { turn, step: 1, message: createSystemMessage('', '@deepseek-ai/dsh-system-prompt') },
+        surfaceOp: 'append',
+      })
+    }
     at({
       type: 'user/message',
       data: {
@@ -53,10 +64,10 @@ function buildSeed(turns: number): string {
       },
       surfaceOp: 'append',
     })
-    at({ type: 'step/start', data: { turn, step: 1 } })
     at({
       type: 'assistant/message',
       data: {
+        stream: [],
         turn,
         step: 1,
         message: {
@@ -66,7 +77,6 @@ function buildSeed(turns: number): string {
           source: { kind: 'model', provider: 'snapshot', model: 'snapshot-replier' },
         },
       },
-      sourceEventSeqs: [],
       surfaceOp: 'append',
     })
     at({ type: 'step/end', data: { turn, step: 1 } })