diff --git a/apps/web/tests/approval-composer.e2e.ts b/apps/web/tests/approval-composer.e2e.ts
index 268549f58f..d1bc84a488 100644
--- a/apps/web/tests/approval-composer.e2e.ts
+++ b/apps/web/tests/approval-composer.e2e.ts
@@ -17,7 +17,7 @@ import {
 import { connectFreshWorkspace, newEnglishPage, saveFailureShot } from './support.ts'
 
 const SNAPSHOT_DIR = fileURLToPath(new URL('../../../snapshots/web/approval-composer', import.meta.url))
-const FIXTURE = join(SNAPSHOT_DIR, 'session.v2.jsonl')
+const FIXTURE = join(SNAPSHOT_DIR, 'session.v3.jsonl')
 // The golden covers the stable waiting panel; direct assertions cover its answer.
 const UI_EXPECTED = join(SNAPSHOT_DIR, 'ui.expected.md')
 const MODE = webSnapshotMode()
@@ -142,6 +142,6 @@ describe('web e2e: approval takeover keeps its actions reachable', () => {
   }, 300_000)
 
   it.skipIf(MODE === 'record')('keeps the fixture inventory closed', async () => {
-    await assertFixtureInventory(SNAPSHOT_DIR, ['session.v2.jsonl', 'ui.expected.md', 'workspace.expected'])
+    await assertFixtureInventory(SNAPSHOT_DIR, ['session.v3.jsonl', 'ui.expected.md', 'workspace.expected'])
   })
 })
diff --git a/apps/web/tests/background-job-list.e2e.ts b/apps/web/tests/background-job-list.e2e.ts
index cb7025435f..f4db98483a 100644
--- a/apps/web/tests/background-job-list.e2e.ts
+++ b/apps/web/tests/background-job-list.e2e.ts
@@ -16,7 +16,7 @@ import {
 } from './scaffold.ts'
 import { newEnglishPage, saveFailureShot } from './support.ts'
 
-const FIXTURE = fileURLToPath(new URL('../../../snapshots/web/fresh-round-trip/session.v2.jsonl', import.meta.url))
+const FIXTURE = fileURLToPath(new URL('../../../snapshots/web/fresh-round-trip/session.v3.jsonl', import.meta.url))
 const SNAPSHOT_DIR = fileURLToPath(new URL('../../../snapshots/web/background-job-list', import.meta.url))
 const RUNNING_EXPECTED = join(SNAPSHOT_DIR, 'running.expected.md')
 const SETTLED_EXPECTED = join(SNAPSHOT_DIR, 'settled.expected.md')
diff --git a/apps/web/tests/bash-abort-row.e2e.ts b/apps/web/tests/bash-abort-row.e2e.ts
index 50fa548e63..ce42436859 100644
--- a/apps/web/tests/bash-abort-row.e2e.ts
+++ b/apps/web/tests/bash-abort-row.e2e.ts
@@ -13,7 +13,7 @@ import {
 } from './scaffold.ts'
 import { newEnglishPage, saveFailureShot } from './support.ts'
 
-const FIXTURE = fileURLToPath(new URL('../../../snapshots/acp/cancel-tool-calls/session.v2.jsonl', import.meta.url))
+const FIXTURE = fileURLToPath(new URL('../../../snapshots/acp/cancel-tool-calls/session.v3.jsonl', import.meta.url))
 const SNAPSHOT_DIR = fileURLToPath(new URL('../../../snapshots/web/bash-abort-row', import.meta.url))
 const UI_EXPECTED = join(SNAPSHOT_DIR, 'ui.expected.md')
 const MODE = webSnapshotMode()
diff --git a/apps/web/tests/cordis-tool-round.e2e.ts b/apps/web/tests/cordis-tool-round.e2e.ts
index 2b7c75b547..1000bc0aaf 100644
--- a/apps/web/tests/cordis-tool-round.e2e.ts
+++ b/apps/web/tests/cordis-tool-round.e2e.ts
@@ -20,7 +20,7 @@ import {
 } from './scaffold.ts'
 import { connectFreshWorkspace, expandOwningTurnProcess, newEnglishPage, saveFailureShot } from './support.ts'
 
-const FIXTURE = fileURLToPath(new URL('../../../snapshots/web/cordis-tool-round/session.v2.jsonl', import.meta.url))
+const FIXTURE = fileURLToPath(new URL('../../../snapshots/web/cordis-tool-round/session.v3.jsonl', import.meta.url))
 const UI_EXPECTED = fileURLToPath(new URL('../../../snapshots/web/cordis-tool-round/ui.expected.md', import.meta.url))
 const MODE = webSnapshotMode()
 const CORDIS_TOOLS = ['cordis_inspect_self', 'cordis_define', 'cordis_run', 'cordis_stop'] as const
diff --git a/apps/web/tests/details-session-lifecycle.e2e.ts b/apps/web/tests/details-session-lifecycle.e2e.ts
index b903c0c102..722a31b303 100644
--- a/apps/web/tests/details-session-lifecycle.e2e.ts
+++ b/apps/web/tests/details-session-lifecycle.e2e.ts
@@ -16,8 +16,8 @@ import { connectFreshWorkspace, newEnglishPage, saveFailureShot } from './suppor
 
 const SNAPSHOT_DIR = fileURLToPath(new URL('../../../snapshots/web/details-session-lifecycle', import.meta.url))
 const HANDLES_EXPECTED = join(SNAPSHOT_DIR, 'handles.expected.md')
-const FIXTURE = fileURLToPath(new URL('../../../snapshots/web/lifecycle-chrome/session.v2.jsonl', import.meta.url))
-const SEED_FIXTURE = fileURLToPath(new URL('../../../snapshots/web/seeded-history/session.v2.jsonl', import.meta.url))
+const FIXTURE = fileURLToPath(new URL('../../../snapshots/web/lifecycle-chrome/session.v3.jsonl', import.meta.url))
+const SEED_FIXTURE = fileURLToPath(new URL('../../../snapshots/web/seeded-history/session.v3.jsonl', import.meta.url))
 const PROMPT = 'Reply with the single word LIGHTHOUSE and stop.'
 const MODE = webSnapshotMode()
 
diff --git a/apps/web/tests/feedback-command.e2e.ts b/apps/web/tests/feedback-command.e2e.ts
index 9e4a7be60e..35d037fb1d 100644
--- a/apps/web/tests/feedback-command.e2e.ts
+++ b/apps/web/tests/feedback-command.e2e.ts
@@ -18,7 +18,7 @@ import {
 import { connectFreshWorkspace, newEnglishPage, saveFailureShot } from './support.ts'
 
 const SNAPSHOT_DIR = fileURLToPath(new URL('../../../snapshots/web/feedback-command', import.meta.url))
-const FIXTURE = join(SNAPSHOT_DIR, 'session.v2.jsonl')
+const FIXTURE = join(SNAPSHOT_DIR, 'session.v3.jsonl')
 const ACK_EXPECTED = join(SNAPSHOT_DIR, 'ack.expected.md')
 const ACK_EXPANDED_EXPECTED = join(SNAPSHOT_DIR, 'ack-expanded.expected.md')
 const MODE = webSnapshotMode()
@@ -96,7 +96,7 @@ describe('web e2e: /feedback command acknowledgement', () => {
 
   it.skipIf(MODE === 'record')('keeps the fixture inventory closed', async () => {
     await assertFixtureInventory(SNAPSHOT_DIR, [
-      'session.v2.jsonl', 'ack.expected.md', 'ack-expanded.expected.md',
+      'session.v3.jsonl', 'ack.expected.md', 'ack-expanded.expected.md',
     ])
   })
 })
diff --git a/apps/web/tests/feedback-release.e2e.ts b/apps/web/tests/feedback-release.e2e.ts
index e4659aa622..f71605dde9 100644
--- a/apps/web/tests/feedback-release.e2e.ts
+++ b/apps/web/tests/feedback-release.e2e.ts
@@ -19,7 +19,7 @@ import { connectFreshWorkspace, newEnglishPage, saveFailureShot } from './suppor
 
 const SNAPSHOT_DIR = fileURLToPath(new URL('../../../snapshots/web/feedback-release', import.meta.url))
 // Both routes borrow the same settled turn; this manifest references its owner.
-const FIXTURE = fileURLToPath(new URL('../../../snapshots/web/feedback-command/session.v2.jsonl', import.meta.url))
+const FIXTURE = fileURLToPath(new URL('../../../snapshots/web/feedback-command/session.v3.jsonl', import.meta.url))
 const ACK_EXPECTED = join(SNAPSHOT_DIR, 'ack.expected.md')
 const ACK_EXPANDED_EXPECTED = join(SNAPSHOT_DIR, 'ack-expanded.expected.md')
 const RELEASE_EXPECTED = join(SNAPSHOT_DIR, 'feedback-release.expected.json')
@@ -110,7 +110,7 @@ describe.each(MODE === 'record' ? ['deepseek-official'] : ['deepseek-official',
           { id: 'feedback-mock', name: 'Feedback mock', contextWindow: 128_000 },
         ] },
       ],
-      // The replayed session.v2.jsonl belongs to the feedback-command scenario;
+      // The replayed session.v3.jsonl belongs to the feedback-command scenario;
       // comparing (or refreshing) the persisted session here would rewrite
       // that shared source with this lane's feedback events. Persistence and
       // collector assertions belong to this lane.
diff --git a/apps/web/tests/file-upload-round.e2e.ts b/apps/web/tests/file-upload-round.e2e.ts
index 409c46ca6c..d39babbf16 100644
--- a/apps/web/tests/file-upload-round.e2e.ts
+++ b/apps/web/tests/file-upload-round.e2e.ts
@@ -6,7 +6,7 @@
 // content-addressed store makes the saved path identical across record and
 // replay once the workspace cwd is tokenized, so the recorded read arguments
 // replay verbatim against a freshly re-uploaded object.
-// Record: DSH_SNAPSHOT=record rewrites session.v2.jsonl, then a keyless
+// Record: DSH_SNAPSHOT=record rewrites session.v3.jsonl, then a keyless
 // DSH_SNAPSHOT=refresh regenerates ui.expected.md.
 import { readFile } from 'node:fs/promises'
 import { fileURLToPath } from 'node:url'
@@ -21,7 +21,7 @@ import {
 import { connectFreshWorkspace, newEnglishPage, saveFailureShot } from './support.ts'
 
 const SNAPSHOT_DIR = fileURLToPath(new URL('../../../snapshots/web/file-upload-round', import.meta.url))
-const FIXTURE = fileURLToPath(new URL('../../../snapshots/web/file-upload-round/session.v2.jsonl', import.meta.url))
+const FIXTURE = fileURLToPath(new URL('../../../snapshots/web/file-upload-round/session.v3.jsonl', import.meta.url))
 const UI_EXPECTED = fileURLToPath(new URL('../../../snapshots/web/file-upload-round/ui.expected.md', import.meta.url))
 const TRAJECTORY_EXPECTED = fileURLToPath(new URL('../../../snapshots/web/file-upload-round/trajectory.expected.md', import.meta.url))
 const OVERRIDE = fileURLToPath(new URL('../../../snapshots/web/file-upload-round/replay.override.json', import.meta.url))
@@ -277,7 +277,7 @@ describe('web e2e: generic file upload through the real assembly', () => {
     expect(tripwire.pageErrors).toEqual([])
     expect(tripwire.warnings).toEqual([])
     await assertFixtureInventory(SNAPSHOT_DIR, [
-      'session.v2.jsonl', 'replay.override.json', 'ui.expected.md', 'trajectory.expected.md',
+      'session.v3.jsonl', 'replay.override.json', 'ui.expected.md', 'trajectory.expected.md',
     ])
   })
 })
diff --git a/apps/web/tests/goal-multi-turn-actions.e2e.ts b/apps/web/tests/goal-multi-turn-actions.e2e.ts
index 4259e71ab9..9b6ebf857f 100644
--- a/apps/web/tests/goal-multi-turn-actions.e2e.ts
+++ b/apps/web/tests/goal-multi-turn-actions.e2e.ts
@@ -17,7 +17,7 @@ import {
 import { connectFreshWorkspace, newEnglishPage, saveFailureShot } from './support.ts'
 
 const SNAPSHOT_DIR = fileURLToPath(new URL('../../../snapshots/web/goal-multi-turn-actions', import.meta.url))
-const FIXTURE = join(SNAPSHOT_DIR, 'session.v2.jsonl')
+const FIXTURE = join(SNAPSHOT_DIR, 'session.v3.jsonl')
 const OVERRIDE = join(SNAPSHOT_DIR, 'replay.override.json')
 const UI_EXPECTED = join(SNAPSHOT_DIR, 'ui.expected.md')
 const UI_EXPANDED_EXPECTED = join(SNAPSHOT_DIR, 'ui-expanded.expected.md')
@@ -178,7 +178,7 @@ describe('web e2e: Goal keeps one assistant action row per completed turn', () =
 
   it.skipIf(MODE === 'record')('keeps a closed fixture inventory', async () => {
     await assertFixtureInventory(SNAPSHOT_DIR, [
-      'replay.override.json', 'session.v2.jsonl', 'ui.expected.md', 'ui-expanded.expected.md',
+      'replay.override.json', 'session.v3.jsonl', 'ui.expected.md', 'ui-expanded.expected.md',
     ])
   })
 })
diff --git a/apps/web/tests/lifecycle-chrome.e2e.ts b/apps/web/tests/lifecycle-chrome.e2e.ts
index 6052ea0a88..439aa8f0b8 100644
--- a/apps/web/tests/lifecycle-chrome.e2e.ts
+++ b/apps/web/tests/lifecycle-chrome.e2e.ts
@@ -27,7 +27,7 @@ import {
 } from './support.ts'
 
 const SNAPSHOT_DIR = fileURLToPath(new URL('../../../snapshots/web/lifecycle-chrome', import.meta.url))
-const FIXTURE = join(SNAPSHOT_DIR, 'session.v2.jsonl')
+const FIXTURE = join(SNAPSHOT_DIR, 'session.v3.jsonl')
 const REPLAY_OVERRIDE = join(SNAPSHOT_DIR, 'replay.override.json')
 const HERO_EXPECTED = join(SNAPSHOT_DIR, 'hero.expected.md')
 const COMMAND_MENU_EXPECTED = join(SNAPSHOT_DIR, 'command-menu.expected.md')
@@ -413,7 +413,7 @@ describe('web e2e: lifecycle & chrome (workspace flow / reload / dark mode)', ()
   it.skipIf(MODE === 'record')('keeps the fixture inventory closed', async () => {
     expect(tripwire.warnings).toEqual([])
     await assertFixtureInventory(SNAPSHOT_DIR, [
-      'session.v2.jsonl', 'replay.override.json', 'command-menu.expected.md',
+      'session.v3.jsonl', 'replay.override.json', 'command-menu.expected.md',
       'command-menu-fuzzy.expected.md', 'connection-error.expected.md', 'hero.expected.md', 'plan-active.expected.md',
       'reloaded.expected.md', 'reloaded-expanded.expected.md',
     ])
diff --git a/apps/web/tests/live-interactions.e2e.ts b/apps/web/tests/live-interactions.e2e.ts
index 1001b51cf2..aeae5699a6 100644
--- a/apps/web/tests/live-interactions.e2e.ts
+++ b/apps/web/tests/live-interactions.e2e.ts
@@ -30,7 +30,7 @@ import {
 import { connectFreshWorkspace, newEnglishPage, saveFailureShot } from './support.ts'
 
 const SNAPSHOT_DIR = fileURLToPath(new URL('../../../snapshots/web/live-interactions', import.meta.url))
-const FIXTURE = join(SNAPSHOT_DIR, 'session.v2.jsonl')
+const FIXTURE = join(SNAPSHOT_DIR, 'session.v3.jsonl')
 // One golden pins the empty mid-turn loading state, one pins the sendable draft
 // state, and the other four capture what remains after cancel, after a
 // non-retryable failure, after retry recovery, and after retry exhaustion.
@@ -325,7 +325,7 @@ describe('web e2e: live-turn interactions (cancel / error / retry)', () => {
 
   it.skipIf(MODE === 'record')('keeps the fixture inventory closed', async () => {
     await assertFixtureInventory(SNAPSHOT_DIR, [
-      'session.v2.jsonl', 'cancel.expected.md', 'cancel-expanded.expected.md',
+      'session.v3.jsonl', 'cancel.expected.md', 'cancel-expanded.expected.md',
       'loading.expected.md', 'running-draft.expected.md', 'error-auth.expected.md',
       'retry.expected.md', 'retry-expanded.expected.md', 'retry-exhausted.expected.md',
     ])
diff --git a/apps/web/tests/message-actions.e2e.ts b/apps/web/tests/message-actions.e2e.ts
index 20cb26da03..68feb8c0d5 100644
--- a/apps/web/tests/message-actions.e2e.ts
+++ b/apps/web/tests/message-actions.e2e.ts
@@ -19,7 +19,7 @@ import { newEnglishPage, saveFailureShot } from './support.ts'
 const SNAPSHOT_DIR = fileURLToPath(new URL('../../../snapshots/web/message-actions', import.meta.url))
 // Borrowed read-only: this scenario needs any settled user+assistant pair, not
 // a new recording (workspace-management / sidebar-scrollbar pattern).
-const SEED = fileURLToPath(new URL('../../../snapshots/web/seeded-history/session.v2.jsonl', import.meta.url))
+const SEED = fileURLToPath(new URL('../../../snapshots/web/seeded-history/session.v3.jsonl', import.meta.url))
 const UI_EXPECTED = join(SNAPSHOT_DIR, 'ui.expected.md')
 const FORK_EXPECTED = join(SNAPSHOT_DIR, 'fork.expected.md')
 const MODE = webSnapshotMode()
diff --git a/apps/web/tests/message-feedback-layout.e2e.ts b/apps/web/tests/message-feedback-layout.e2e.ts
index 0f05b722d1..1d3ee180af 100644
--- a/apps/web/tests/message-feedback-layout.e2e.ts
+++ b/apps/web/tests/message-feedback-layout.e2e.ts
@@ -41,7 +41,7 @@ const SNAPSHOT_DIR = fileURLToPath(new URL('../../../snapshots/web/message-feedb
 const GEOMETRY_EXPECTED = join(SNAPSHOT_DIR, 'geometry.expected.md')
 const MODE = webSnapshotMode()
 /** Borrowed read-only: this scenario needs any settled assistant message to rate. */
-const SEED = fileURLToPath(new URL('../../../snapshots/web/seeded-history/session.v2.jsonl', import.meta.url))
+const SEED = fileURLToPath(new URL('../../../snapshots/web/seeded-history/session.v3.jsonl', import.meta.url))
 const SEED_ID = 'message-feedback-layout-e2e'
 /** Viewport widths from full-screen desktop down to a narrow window. */
 const WIDTHS = [1680, 1280, 1024, 900, 700, 600]
diff --git a/apps/web/tests/message-feedback-protocol.snapshot.ts b/apps/web/tests/message-feedback-protocol.snapshot.ts
index e18a32b12d..6936479b61 100644
--- a/apps/web/tests/message-feedback-protocol.snapshot.ts
+++ b/apps/web/tests/message-feedback-protocol.snapshot.ts
@@ -12,7 +12,7 @@ import {
 } from './scaffold.ts'
 
 const SNAPSHOT_DIR = fileURLToPath(new URL('../../../snapshots/web/message-feedback-protocol', import.meta.url))
-const SESSION_FIXTURE = join(SNAPSHOT_DIR, 'session.v2.jsonl')
+const SESSION_FIXTURE = join(SNAPSHOT_DIR, 'session.v3.jsonl')
 const PROTOCOL_EXPECTED = join(SNAPSHOT_DIR, 'protocol.expected.json')
 const SESSION_ID = 'message-feedback-protocol'
 const MESSAGE_ID = fixtureIdentity('message', 2)
@@ -112,6 +112,6 @@ describe('message feedback Host Remote protocol', () => {
 
     expect(exchanges.every(exchange => exchange.status === 200)).toBe(true)
     await compareOrRefreshGolden(PROTOCOL_EXPECTED, normalizeProtocol(exchanges, version), scaffold.mode)
-    await assertFixtureInventory(SNAPSHOT_DIR, ['protocol.expected.json', 'session.v2.jsonl'])
+    await assertFixtureInventory(SNAPSHOT_DIR, ['protocol.expected.json', 'session.v3.jsonl'])
   })
 })
diff --git a/apps/web/tests/message-feedback.e2e.ts b/apps/web/tests/message-feedback.e2e.ts
index efcd992137..62cdb33ef2 100644
--- a/apps/web/tests/message-feedback.e2e.ts
+++ b/apps/web/tests/message-feedback.e2e.ts
@@ -15,7 +15,7 @@ import { newEnglishPage, saveFailureShot } from './support.ts'
 
 // Borrowed read-only: this scenario needs any settled assistant message to
 // address, not a new recording (message-actions / sidebar-scrollbar pattern).
-const SEED = fileURLToPath(new URL('../../../snapshots/web/seeded-history/session.v2.jsonl', import.meta.url))
+const SEED = fileURLToPath(new URL('../../../snapshots/web/seeded-history/session.v3.jsonl', import.meta.url))
 const MODE = webSnapshotMode()
 const SEED_ID = 'message-feedback-web-e2e'
 const NOTE = 'Read both files before answering.'
diff --git a/apps/web/tests/minimal-preset.snapshot.ts b/apps/web/tests/minimal-preset.snapshot.ts
index 406ea9086d..1b34c986b0 100644
--- a/apps/web/tests/minimal-preset.snapshot.ts
+++ b/apps/web/tests/minimal-preset.snapshot.ts
@@ -22,7 +22,7 @@ import {
 import { newEnglishPage, saveFailureShot } from './support.ts'
 
 const SNAPSHOT_DIR = fileURLToPath(new URL('../../../snapshots/web/minimal-preset', import.meta.url))
-const FIXTURE = join(SNAPSHOT_DIR, 'session.v2.jsonl')
+const FIXTURE = join(SNAPSHOT_DIR, 'session.v3.jsonl')
 const UI_EXPECTED = join(SNAPSHOT_DIR, 'ui.expected.md')
 const MODE = webSnapshotMode()
 const PROMPT = "Use the bash tool to run exactly: printf 'MINIMAL_BASH_CARD_OK\\n'. Then reply exactly MINIMAL_PRESET_REQUEST_OK and stop."
@@ -189,7 +189,7 @@ describe('minimal agent preset', () => {
 
   it('keeps its snapshot inventory closed', async () => {
     await assertFixtureInventory(SNAPSHOT_DIR, [
-      'session.v2.jsonl',
+      'session.v3.jsonl',
       'system-prompt.expected.md',
       'tool-schemas.expected.json',
       'ui.expected.md',
diff --git a/apps/web/tests/navigation-panes.e2e.ts b/apps/web/tests/navigation-panes.e2e.ts
index 0e06e222ee..114b97f976 100644
--- a/apps/web/tests/navigation-panes.e2e.ts
+++ b/apps/web/tests/navigation-panes.e2e.ts
@@ -22,7 +22,7 @@ import {
 import { expandOwningTurnProcess, newEnglishPage, saveFailureShot } from './support.ts'
 
 const SNAPSHOT_DIR = fileURLToPath(new URL('../../../snapshots/web/navigation-panes', import.meta.url))
-const SEED = join(SNAPSHOT_DIR, 'session.v2.jsonl')
+const SEED = join(SNAPSHOT_DIR, 'session.v3.jsonl')
 const TRAJECTORY_EXPECTED = join(SNAPSHOT_DIR, 'trajectory.expected.md')
 const SEARCH_EXPECTED = join(SNAPSHOT_DIR, 'search-results.expected.md')
 const TERMINAL_EXPECTED = join(SNAPSHOT_DIR, 'terminal-card.expected.md')
@@ -499,7 +499,7 @@ describe('web e2e: navigation & panes over a rich seeded session', () => {
 
   it.skipIf(MODE === 'record')('keeps the recorded fixture inventory exact', async () => {
     await assertFixtureInventory(SNAPSHOT_DIR, [
-      'session.v2.jsonl', 'search-results.expected.md', 'trajectory.expected.md',
+      'session.v3.jsonl', 'search-results.expected.md', 'trajectory.expected.md',
       'terminal-card.expected.md',
     ])
   })
diff --git a/apps/web/tests/permission-policy-context.e2e.ts b/apps/web/tests/permission-policy-context.e2e.ts
index 863526d19c..f0b9448470 100644
--- a/apps/web/tests/permission-policy-context.e2e.ts
+++ b/apps/web/tests/permission-policy-context.e2e.ts
@@ -18,7 +18,7 @@ import {
 import { connectFreshWorkspace, newEnglishPage, saveFailureShot, writeComposerDraft } from './support.ts'
 
 const SNAPSHOT_DIR = fileURLToPath(new URL('../../../snapshots/web/permission-policy-context', import.meta.url))
-const FIXTURE = fileURLToPath(new URL('../../../snapshots/web/permission-policy-context/session.v2.jsonl', import.meta.url))
+const FIXTURE = fileURLToPath(new URL('../../../snapshots/web/permission-policy-context/session.v3.jsonl', import.meta.url))
 const MODE = webSnapshotMode()
 
 const PROMPTS = [
@@ -168,6 +168,6 @@ describe('web e2e: current sandbox policy reaches the model before tools', () =>
   it.skipIf(MODE === 'record')('stays clean and keeps the fixture inventory closed', async () => {
     expect(tripwire.pageErrors).toEqual([])
     expect(tripwire.warnings).toEqual([])
-    await assertFixtureInventory(SNAPSHOT_DIR, ['session.v2.jsonl', 'workspace.expected'])
+    await assertFixtureInventory(SNAPSHOT_DIR, ['session.v3.jsonl', 'workspace.expected'])
   })
 })
diff --git a/apps/web/tests/plan-control-row.e2e.ts b/apps/web/tests/plan-control-row.e2e.ts
index 7ccf54db9f..a9a1faec95 100644
--- a/apps/web/tests/plan-control-row.e2e.ts
+++ b/apps/web/tests/plan-control-row.e2e.ts
@@ -37,7 +37,7 @@ import {
 import { connectFreshWorkspace, newEnglishPage, saveFailureShot } from './support.ts'
 
 const SNAPSHOT_DIR = fileURLToPath(new URL('../../../snapshots/web/plan-narrow-viewport', import.meta.url))
-const FIXTURE = join(SNAPSHOT_DIR, 'session.v2.jsonl')
+const FIXTURE = join(SNAPSHOT_DIR, 'session.v3.jsonl')
 const LAYOUT_EXPECTED = join(SNAPSHOT_DIR, 'layout.expected.md')
 const MODE = webSnapshotMode()
 
@@ -143,6 +143,6 @@ describe('web e2e: plan chip click area at the narrow viewport', () => {
   }, 200_000)
 
   it('keeps the snapshot inventory closed', async () => {
-    await assertFixtureInventory(SNAPSHOT_DIR, ['session.v2.jsonl', 'layout.expected.md'])
+    await assertFixtureInventory(SNAPSHOT_DIR, ['session.v3.jsonl', 'layout.expected.md'])
   })
 })
diff --git a/apps/web/tests/plan-review.e2e.ts b/apps/web/tests/plan-review.e2e.ts
index ff9e3af4ee..dadaf2d5f6 100644
--- a/apps/web/tests/plan-review.e2e.ts
+++ b/apps/web/tests/plan-review.e2e.ts
@@ -22,7 +22,7 @@ import {
 import { connectFreshWorkspace, newEnglishPage, saveFailureShot } from './support.ts'
 
 const SNAPSHOT_DIR = fileURLToPath(new URL('../../../snapshots/web/plan-review', import.meta.url))
-const FIXTURE = join(SNAPSHOT_DIR, 'session.v2.jsonl')
+const FIXTURE = join(SNAPSHOT_DIR, 'session.v3.jsonl')
 // The waiting golden owns the decision card; the approved golden owns the
 // transcript the approval leaves behind — the state the card cannot see.
 const REVIEW_EXPECTED = join(SNAPSHOT_DIR, 'review.expected.md')
@@ -125,7 +125,7 @@ describe('web e2e: plan review takeover round trip', () => {
 
   it.skipIf(MODE === 'record')('keeps the fixture inventory closed', async () => {
     await assertFixtureInventory(SNAPSHOT_DIR, [
-      'session.v2.jsonl', 'review.expected.md', 'sidebar.expected.md',
+      'session.v3.jsonl', 'review.expected.md', 'sidebar.expected.md',
       'approved.expected.md', 'approved-expanded.expected.md',
     ])
   })
diff --git a/apps/web/tests/ptc-round.e2e.ts b/apps/web/tests/ptc-round.e2e.ts
index 66ff93de30..a5e9cf2abc 100644
--- a/apps/web/tests/ptc-round.e2e.ts
+++ b/apps/web/tests/ptc-round.e2e.ts
@@ -1,5 +1,5 @@
 // PTC mode browser round trip with nested sub-calls and details selection.
-// Record: DSH_SNAPSHOT=record writes session.v2.jsonl, then a keyless
+// Record: DSH_SNAPSHOT=record writes session.v3.jsonl, then a keyless
 // DSH_SNAPSHOT=refresh regenerates ui.expected.md.
 import { readFile } from 'node:fs/promises'
 import { fileURLToPath } from 'node:url'
@@ -13,7 +13,7 @@ import {
 } from './scaffold.ts'
 import { connectFreshWorkspace, expandOwningTurnProcess, newEnglishPage, saveFailureShot } from './support.ts'
 
-const FIXTURE = fileURLToPath(new URL('../../../snapshots/web/ptc-round/session.v2.jsonl', import.meta.url))
+const FIXTURE = fileURLToPath(new URL('../../../snapshots/web/ptc-round/session.v3.jsonl', import.meta.url))
 const UI_EXPECTED = fileURLToPath(new URL('../../../snapshots/web/ptc-round/ui.expected.md', import.meta.url))
 const MODE = webSnapshotMode()
 
diff --git a/apps/web/tests/pwsh-terminal.e2e.ts b/apps/web/tests/pwsh-terminal.e2e.ts
index ec86ddc4b1..6069367555 100644
--- a/apps/web/tests/pwsh-terminal.e2e.ts
+++ b/apps/web/tests/pwsh-terminal.e2e.ts
@@ -25,7 +25,7 @@ import {
 import { connectFreshWorkspace, newEnglishPage, saveFailureShot } from './support.ts'
 
 const SNAPSHOT_DIR = fileURLToPath(new URL('../../../snapshots/web/pwsh-terminal', import.meta.url))
-const SEED = join(SNAPSHOT_DIR, 'session.v2.jsonl')
+const SEED = join(SNAPSHOT_DIR, 'session.v3.jsonl')
 const TERMINAL_EXPECTED = join(SNAPSHOT_DIR, 'terminal-card.expected.md')
 const OVERLAY = fileURLToPath(new URL('./pwsh-terminal.overlay.yml', import.meta.url))
 const PROMPT = 'Run a PowerShell command that fails, then stop.'
@@ -101,6 +101,6 @@ describe.skipIf(MODE === 'record' || !HAS_PWSH)('web e2e: pwsh calls use the bas
   }, 60_000)
 
   it('guards the lane fixture inventory', async () => {
-    await assertFixtureInventory(SNAPSHOT_DIR, ['session.v2.jsonl', 'terminal-card.expected.md'])
+    await assertFixtureInventory(SNAPSHOT_DIR, ['session.v3.jsonl', 'terminal-card.expected.md'])
   })
 })
diff --git a/apps/web/tests/question-composer.e2e.ts b/apps/web/tests/question-composer.e2e.ts
index d12abc2712..45ba98f7ac 100644
--- a/apps/web/tests/question-composer.e2e.ts
+++ b/apps/web/tests/question-composer.e2e.ts
@@ -24,7 +24,7 @@ import {
 } from './support.ts'
 
 const SNAPSHOT_DIR = fileURLToPath(new URL('../../../snapshots/web/question-composer', import.meta.url))
-const FIXTURE = join(SNAPSHOT_DIR, 'session.v2.jsonl')
+const FIXTURE = join(SNAPSHOT_DIR, 'session.v3.jsonl')
 const UI_EXPECTED = join(SNAPSHOT_DIR, 'ui.expected.md')
 const SIDEBAR_EXPECTED = join(SNAPSHOT_DIR, 'sidebar.expected.md')
 const COMPOSED_EXPECTED = join(SNAPSHOT_DIR, 'composed.expected.md')
@@ -410,7 +410,7 @@ describe.skipIf(MODE === 'record')('web e2e: cancelled question transcript', ()
 
   it('keeps the fixture inventory closed', async () => {
     await assertFixtureInventory(SNAPSHOT_DIR, [
-      'session.v2.jsonl',
+      'session.v3.jsonl',
       'ui.expected.md',
       'sidebar.expected.md',
       'composed.expected.md',
diff --git a/apps/web/tests/queue-actions.e2e.ts b/apps/web/tests/queue-actions.e2e.ts
index 2f45d38d37..d47324474f 100644
--- a/apps/web/tests/queue-actions.e2e.ts
+++ b/apps/web/tests/queue-actions.e2e.ts
@@ -19,7 +19,7 @@ import {
 import { connectFreshWorkspace, newEnglishPage, saveFailureShot } from './support.ts'
 
 const SNAPSHOT_DIR = fileURLToPath(new URL('../../../snapshots/web/queue-actions', import.meta.url))
-const FIXTURE = fileURLToPath(new URL('../../../snapshots/web/live-interactions/session.v2.jsonl', import.meta.url))
+const FIXTURE = fileURLToPath(new URL('../../../snapshots/web/live-interactions/session.v3.jsonl', import.meta.url))
 const COLLAPSED_EXPECTED = join(SNAPSHOT_DIR, 'collapsed.expected.md')
 const EDITING_EXPECTED = join(SNAPSHOT_DIR, 'editing.expected.md')
 const LAYOUT_EXPECTED = join(SNAPSHOT_DIR, 'layout.expected.md')
diff --git a/apps/web/tests/queue-image.e2e.ts b/apps/web/tests/queue-image.e2e.ts
index 9e641bc77c..faa675affc 100644
--- a/apps/web/tests/queue-image.e2e.ts
+++ b/apps/web/tests/queue-image.e2e.ts
@@ -21,7 +21,7 @@ import {
 import { connectFreshWorkspace, newEnglishPage, saveFailureShot } from './support.ts'
 
 const SNAPSHOT_DIR = fileURLToPath(new URL('../../../snapshots/web/queued-image', import.meta.url))
-const FIXTURE = fileURLToPath(new URL('../../../snapshots/web/live-interactions/session.v2.jsonl', import.meta.url))
+const FIXTURE = fileURLToPath(new URL('../../../snapshots/web/live-interactions/session.v3.jsonl', import.meta.url))
 const PNG = fileURLToPath(new URL('../../../snapshots/session/read-image/workspace/red.png', import.meta.url))
 const QUEUED_EXPECTED = join(SNAPSHOT_DIR, 'queued.expected.md')
 const DELIVERED_EXPECTED = join(SNAPSHOT_DIR, 'delivered.expected.md')
diff --git a/apps/web/tests/replay-round-trip.e2e.ts b/apps/web/tests/replay-round-trip.e2e.ts
index ca634d7ffd..f51fa2e2fa 100644
--- a/apps/web/tests/replay-round-trip.e2e.ts
+++ b/apps/web/tests/replay-round-trip.e2e.ts
@@ -6,7 +6,7 @@
 // record cannot hang on a live model answering differently); assertion steps
 // run in replay/refresh only. Settled states only — streaming fidelity is
 // asserted from the durable embedded Assistant stream, not transient DOM.
-// Record: DSH_SNAPSHOT=record writes session.v2.jsonl, then a keyless
+// Record: DSH_SNAPSHOT=record writes session.v3.jsonl, then a keyless
 // DSH_SNAPSHOT=refresh regenerates ui.expected.md.
 import { readFile } from 'node:fs/promises'
 import { join } from 'node:path'
@@ -26,7 +26,7 @@ import {
 } from './support.ts'
 
 const SNAPSHOT_DIR = fileURLToPath(new URL('../../../snapshots/web/fresh-round-trip', import.meta.url))
-const FIXTURE = fileURLToPath(new URL('../../../snapshots/web/fresh-round-trip/session.v2.jsonl', import.meta.url))
+const FIXTURE = fileURLToPath(new URL('../../../snapshots/web/fresh-round-trip/session.v3.jsonl', import.meta.url))
 const UI_EXPECTED = fileURLToPath(new URL('../../../snapshots/web/fresh-round-trip/ui.expected.md', import.meta.url))
 const ECHO_EXPECTED = fileURLToPath(new URL('../../../snapshots/web/fresh-round-trip/submission-echo.expected.md', import.meta.url))
 const UI_EXPANDED_EXPECTED = fileURLToPath(
@@ -224,7 +224,7 @@ describe('web e2e: fresh round trip through the real assembly', () => {
     expect(tripwire.pageErrors).toEqual([])
     expect(tripwire.warnings).toEqual([])
     await assertFixtureInventory(SNAPSHOT_DIR, [
-      'session.v2.jsonl',
+      'session.v3.jsonl',
       'submission-echo.expected.md',
       'system-prompt.expected.md',
       'tool-schemas.expected.json',
diff --git a/apps/web/tests/schedule-after.e2e.ts b/apps/web/tests/schedule-after.e2e.ts
index adf5ca1b1e..587a355f4f 100644
--- a/apps/web/tests/schedule-after.e2e.ts
+++ b/apps/web/tests/schedule-after.e2e.ts
@@ -58,7 +58,7 @@ const EVERY_REPLY = 'Reminders: Check primary metrics; Check secondary metrics.'
 const EVERY_INTERVAL_SECONDS = 60 * 60
 const EVERY_FIXTURE_AGE_MS = 90 * 60 * 1_000
 const CATALOG_SNAPSHOT_DIR = fileURLToPath(new URL('../../../snapshots/web/schedule-catalog', import.meta.url))
-const CATALOG_FIXTURE = join(CATALOG_SNAPSHOT_DIR, 'session.v2.jsonl')
+const CATALOG_FIXTURE = join(CATALOG_SNAPSHOT_DIR, 'session.v3.jsonl')
 const CATALOG_EXPECTED = join(CATALOG_SNAPSHOT_DIR, 'catalog.expected.md')
 const BASE_PATCH = fileURLToPath(new URL('../../../packages/bundle/base/cordis.patch.yml', import.meta.url))
 const WEB_PATCH = fileURLToPath(new URL('../../../packages/bundle/web-app/cordis.patch.yml', import.meta.url))
@@ -816,7 +816,7 @@ describe.skipIf(MODE === 'record')('web e2e: active Schedule catalog', () => {
     }).toBe(0)
     await assertFixtureInventory(CATALOG_SNAPSHOT_DIR, [
       'catalog.expected.md',
-      'session.v2.jsonl',
+      'session.v3.jsonl',
       'system-prompt.expected.md',
       'tool-schemas.expected.json',
     ])
diff --git a/apps/web/tests/seeded-history.e2e.ts b/apps/web/tests/seeded-history.e2e.ts
index 925bb5322b..5fbb39a15c 100644
--- a/apps/web/tests/seeded-history.e2e.ts
+++ b/apps/web/tests/seeded-history.e2e.ts
@@ -9,7 +9,7 @@
 // `/feedback` pins its expandable correlation ids. The seed is a recorded
 // fixture under the same record discipline as every other: DSH_SNAPSHOT=record drives the turn
 // live through the composer (real read tool against seeded workspace files)
-// and harvests session.v2.jsonl; replay/refresh seed it cold and only render.
+// and harvests session.v3.jsonl; replay/refresh seed it cold and only render.
 import { readFile, writeFile, mkdir } from 'node:fs/promises'
 import { fileURLToPath } from 'node:url'
 import type { Browser, Page } from 'playwright'
@@ -30,7 +30,7 @@ import {
 import { expandOwningTurnProcess, newEnglishPage, saveFailureShot } from './support.ts'
 
 const SNAPSHOT_DIR = fileURLToPath(new URL('../../../snapshots/web/seeded-history', import.meta.url))
-const SEED = fileURLToPath(new URL('../../../snapshots/web/seeded-history/session.v2.jsonl', import.meta.url))
+const SEED = fileURLToPath(new URL('../../../snapshots/web/seeded-history/session.v3.jsonl', import.meta.url))
 const UI_EXPECTED = fileURLToPath(new URL('../../../snapshots/web/seeded-history/ui.expected.md', import.meta.url))
 const UI_EXPANDED_EXPECTED = fileURLToPath(
   new URL('../../../snapshots/web/seeded-history/ui-expanded.expected.md', import.meta.url),
@@ -564,7 +564,7 @@ describe('web e2e: seeded history renders through cold resume', () => {
     expect(tripwire.warnings).toEqual([])
     await assertFixtureInventory(SNAPSHOT_DIR, [
       'command-row.expected.md', 'feedback-row.expected.md', 'file-open-failure.expected.md',
-      'session.v2.jsonl', 'ui.expected.md', 'ui-expanded.expected.md',
+      'session.v3.jsonl', 'ui.expected.md', 'ui-expanded.expected.md',
     ])
   })
 })
diff --git a/apps/web/tests/sidebar-scrollbar.e2e.ts b/apps/web/tests/sidebar-scrollbar.e2e.ts
index d1c14f0379..0f1443c8d9 100644
--- a/apps/web/tests/sidebar-scrollbar.e2e.ts
+++ b/apps/web/tests/sidebar-scrollbar.e2e.ts
@@ -15,7 +15,7 @@ import {
 } from './scaffold.ts'
 import { newEnglishPage, saveFailureShot } from './support.ts'
 
-const SEED = fileURLToPath(new URL('../../../snapshots/web/seeded-history/session.v2.jsonl', import.meta.url))
+const SEED = fileURLToPath(new URL('../../../snapshots/web/seeded-history/session.v3.jsonl', import.meta.url))
 const SNAPSHOT_DIR = fileURLToPath(new URL('../../../snapshots/web/sidebar-scrollbar', import.meta.url))
 /** Geometry and resolved style are absent from ARIA snapshots, so this scenario records them directly. */
 const GEOMETRY_EXPECTED = join(SNAPSHOT_DIR, 'geometry.expected.md')
@@ -412,7 +412,7 @@ describe('web e2e: sidebar session list scrollbar (reserved gutter / themed thum
   }, 60_000)
 
   it('commits exactly the fixtures it reads', async () => {
-    // The scenario borrows seeded-history's session.v2.jsonl rather than committing a
+    // The scenario borrows seeded-history's session.v3.jsonl rather than committing a
     // second copy, so this directory holds the golden alone.
     await assertFixtureInventory(SNAPSHOT_DIR, ['geometry.expected.md'])
   })
diff --git a/apps/web/tests/skill-tool-row.e2e.ts b/apps/web/tests/skill-tool-row.e2e.ts
index d32e50ea86..ce84e0b76e 100644
--- a/apps/web/tests/skill-tool-row.e2e.ts
+++ b/apps/web/tests/skill-tool-row.e2e.ts
@@ -12,7 +12,7 @@ import {
 } from './scaffold.ts'
 import { expandOwningTurnProcess, newEnglishPage, saveFailureShot } from './support.ts'
 
-const FIXTURE = fileURLToPath(new URL('../../../snapshots/session/skill-load/session.v2.jsonl', import.meta.url))
+const FIXTURE = fileURLToPath(new URL('../../../snapshots/session/skill-load/session.v3.jsonl', import.meta.url))
 const SNAPSHOT_DIR = fileURLToPath(new URL('../../../snapshots/web/skill-tool-row', import.meta.url))
 const UI_EXPECTED = fileURLToPath(new URL('../../../snapshots/web/skill-tool-row/ui.expected.md', import.meta.url))
 const MODE = webSnapshotMode()
diff --git a/apps/web/tests/steering.e2e.ts b/apps/web/tests/steering.e2e.ts
index f96fbdbe1f..b73f0d5c5d 100644
--- a/apps/web/tests/steering.e2e.ts
+++ b/apps/web/tests/steering.e2e.ts
@@ -19,7 +19,7 @@ import {
 import { connectFreshWorkspace, newEnglishPage, saveFailureShot } from './support.ts'
 
 const SNAPSHOT_DIR = fileURLToPath(new URL('../../../snapshots/web/steering', import.meta.url))
-const FIXTURE = join(SNAPSHOT_DIR, 'session.v2.jsonl')
+const FIXTURE = join(SNAPSHOT_DIR, 'session.v3.jsonl')
 // Two goldens pin the transient Host projection and its durable handoff: the
 // mid-turn state renders accepted steering from the Session control queue while the
 // question blocks admission, then the settled state renders the same message
@@ -186,7 +186,7 @@ describe('web e2e: mid-turn steering lands durably and visibly', () => {
 
   it.skipIf(MODE === 'record')('keeps the fixture inventory closed', async () => {
     await assertFixtureInventory(SNAPSHOT_DIR, [
-      'session.v2.jsonl', 'mid-steer.expected.md', 'settled.expected.md', 'settled-expanded.expected.md',
+      'session.v3.jsonl', 'mid-steer.expected.md', 'settled.expected.md', 'settled-expanded.expected.md',
     ])
   })
 })
diff --git a/apps/web/tests/subagent-conversation.e2e.ts b/apps/web/tests/subagent-conversation.e2e.ts
index d9b66749de..dfca321123 100644
--- a/apps/web/tests/subagent-conversation.e2e.ts
+++ b/apps/web/tests/subagent-conversation.e2e.ts
@@ -19,7 +19,7 @@ import {
 } from './scaffold.ts'
 import { connectFreshWorkspace, newEnglishPage, saveFailureShot } from './support.ts'
 
-const BASE_FIXTURE = fileURLToPath(new URL('../../../snapshots/web/live-interactions/session.v2.jsonl', import.meta.url))
+const BASE_FIXTURE = fileURLToPath(new URL('../../../snapshots/web/live-interactions/session.v3.jsonl', import.meta.url))
 const AVAILABLE_CHILD_EXPECTED = fileURLToPath(new URL('../../../snapshots/web/subagent-conversation/ui.expected.md', import.meta.url))
 const AVAILABLE_CHILD_EXPANDED_EXPECTED = fileURLToPath(
   new URL('../../../snapshots/web/subagent-conversation/ui-expanded.expected.md', import.meta.url),
diff --git a/apps/web/tests/subagent-interrupt-ui.e2e.ts b/apps/web/tests/subagent-interrupt-ui.e2e.ts
index 5cf3efa820..e6653f1cec 100644
--- a/apps/web/tests/subagent-interrupt-ui.e2e.ts
+++ b/apps/web/tests/subagent-interrupt-ui.e2e.ts
@@ -27,7 +27,7 @@ import {
 } from './scaffold.ts'
 import { connectFreshWorkspace, newEnglishPage, saveFailureShot } from './support.ts'
 
-const BASE_FIXTURE = fileURLToPath(new URL('../../../snapshots/web/live-interactions/session.v2.jsonl', import.meta.url))
+const BASE_FIXTURE = fileURLToPath(new URL('../../../snapshots/web/live-interactions/session.v3.jsonl', import.meta.url))
 
 const SNAPSHOT_DIR = fileURLToPath(new URL('../../../snapshots/web/subagent-interrupt', import.meta.url))
 const OFFLINE_COMPOSER_EXPECTED = join(SNAPSHOT_DIR, 'offline-composer.expected.md')
diff --git a/apps/web/tests/turn-tail-actions.e2e.ts b/apps/web/tests/turn-tail-actions.e2e.ts
index 1ae0f8be62..9457407c0a 100644
--- a/apps/web/tests/turn-tail-actions.e2e.ts
+++ b/apps/web/tests/turn-tail-actions.e2e.ts
@@ -23,7 +23,7 @@ import {
 import { connectFreshWorkspace, newEnglishPage, saveFailureShot } from './support.ts'
 
 const SNAPSHOT_DIR = fileURLToPath(new URL('../../../snapshots/web/turn-tail-actions', import.meta.url))
-const FIXTURE = join(SNAPSHOT_DIR, 'session.v2.jsonl')
+const FIXTURE = join(SNAPSHOT_DIR, 'session.v3.jsonl')
 // Three goldens for the same message: parked mid-turn, aborted, and completed.
 const RUNNING_EXPECTED = join(SNAPSHOT_DIR, 'running.expected.md')
 const SETTLED_EXPECTED = join(SNAPSHOT_DIR, 'settled.expected.md')
@@ -291,7 +291,7 @@ describe('web e2e: assistant IconActions wait for the turn to end', () => {
     await assertFixtureInventory(
       SNAPSHOT_DIR,
       [
-        'completed.expected.md', 'focused.expected.md', 'running.expected.md', 'session.v2.jsonl',
+        'completed.expected.md', 'focused.expected.md', 'running.expected.md', 'session.v3.jsonl',
         'settled.expected.md', 'usage-expanded.expected.md',
       ],
     )
diff --git a/apps/web/tests/web-search-round.e2e.ts b/apps/web/tests/web-search-round.e2e.ts
index 7ffde8594f..4128d0d46e 100644
--- a/apps/web/tests/web-search-round.e2e.ts
+++ b/apps/web/tests/web-search-round.e2e.ts
@@ -19,7 +19,7 @@ import {
 import { connectFreshWorkspace, expandOwningTurnProcess, newEnglishPage, saveFailureShot } from './support.ts'
 
 const SNAPSHOT_DIR = fileURLToPath(new URL('../../../snapshots/web/web-search-round', import.meta.url))
-const FIXTURE = fileURLToPath(new URL('../../../snapshots/web/web-search-round/session.v2.jsonl', import.meta.url))
+const FIXTURE = fileURLToPath(new URL('../../../snapshots/web/web-search-round/session.v3.jsonl', import.meta.url))
 const UI_EXPECTED = fileURLToPath(new URL('../../../snapshots/web/web-search-round/ui.expected.md', import.meta.url))
 const MODE = webSnapshotMode()
 const QUERIES = ['DeepSeek Harness snapshot search', 'DeepSeek Harness multi-query search'] as const
@@ -323,6 +323,6 @@ describe('web e2e: shipped default web search', () => {
   it.skipIf(MODE === 'record')('stayed clean and kept the exact fixture inventory', async () => {
     expect(tripwire.pageErrors).toEqual([])
     expect(tripwire.warnings).toEqual([])
-    await assertFixtureInventory(SNAPSHOT_DIR, ['session.v2.jsonl', 'ui.expected.md'])
+    await assertFixtureInventory(SNAPSHOT_DIR, ['session.v3.jsonl', 'ui.expected.md'])
   })
 })
diff --git a/apps/web/tests/workflow-run.e2e.ts b/apps/web/tests/workflow-run.e2e.ts
index 08f4c5e193..5b800d4b74 100644
--- a/apps/web/tests/workflow-run.e2e.ts
+++ b/apps/web/tests/workflow-run.e2e.ts
@@ -22,8 +22,8 @@ const MODE = webSnapshotMode()
 const SNAPSHOT_DIR = fileURLToPath(new URL('../../../snapshots/web/workflow-run', import.meta.url))
 const UI_LIVE_EXPECTED = join(SNAPSHOT_DIR, 'ui-live.expected.md')
 const UI_EXPECTED = join(SNAPSHOT_DIR, 'ui.expected.md')
-const PARENT_FIXTURE = join(REPO_ROOT, 'snapshots/session/workflow-run/session.v2.jsonl')
-const CHILD_FIXTURE = join(REPO_ROOT, 'snapshots/session/workflow-run/session.1.v2.jsonl')
+const PARENT_FIXTURE = join(REPO_ROOT, 'snapshots/session/workflow-run/session.v3.jsonl')
+const CHILD_FIXTURE = join(REPO_ROOT, 'snapshots/session/workflow-run/session.1.v3.jsonl')
 const CHILD_PROMPT = 'Reply with exactly the word WF_CHILD_OK and nothing else.'
 
 describe.skipIf(MODE === 'record')('web e2e: durable workflow run in Chat', () => {
diff --git a/apps/web/tests/workspace-management.e2e.ts b/apps/web/tests/workspace-management.e2e.ts
index 382e549ddf..ee64883339 100644
--- a/apps/web/tests/workspace-management.e2e.ts
+++ b/apps/web/tests/workspace-management.e2e.ts
@@ -28,7 +28,7 @@ import { newEnglishPage, saveFailureShot } from './support.ts'
 const SNAPSHOT_DIR = fileURLToPath(new URL('../../../snapshots/web/workspace-management', import.meta.url))
 // The seed is another scenario's committed fixture, reused read-only: this
 // spec needs any one cold session row, not new recorded content.
-const SEED = fileURLToPath(new URL('../../../snapshots/web/seeded-history/session.v2.jsonl', import.meta.url))
+const SEED = fileURLToPath(new URL('../../../snapshots/web/seeded-history/session.v3.jsonl', import.meta.url))
 const MODE = webSnapshotMode()
 const BROWSER_EXPECTED = join(SNAPSHOT_DIR, 'directory-browser.expected.md')
 const SEED_ID = 'workspace-management-web-e2e'
diff --git a/apps/web/tests/workspace-new-session-folding.e2e.ts b/apps/web/tests/workspace-new-session-folding.e2e.ts
index 8e45770e2f..21bdd58871 100644
--- a/apps/web/tests/workspace-new-session-folding.e2e.ts
+++ b/apps/web/tests/workspace-new-session-folding.e2e.ts
@@ -20,7 +20,7 @@ import { newEnglishPage, saveFailureShot } from './support.ts'
 
 const EXPECTED_DIR = fileURLToPath(new URL('./expected/workspace-new-session-folding', import.meta.url))
 const SIDEBAR_EXPECTED = join(EXPECTED_DIR, 'sidebar.expected.md')
-const SEED = fileURLToPath(new URL('../../../snapshots/web/message-feedback-protocol/session.v2.jsonl', import.meta.url))
+const SEED = fileURLToPath(new URL('../../../snapshots/web/message-feedback-protocol/session.v3.jsonl', import.meta.url))
 const MODE = webSnapshotMode()
 const EXISTING_SESSION_COUNT = 6
 
diff --git a/packages/test-support/session-snapshot/src/index.ts b/packages/test-support/session-snapshot/src/index.ts
index 771560de8b..1b53cccfe2 100644
--- a/packages/test-support/session-snapshot/src/index.ts
+++ b/packages/test-support/session-snapshot/src/index.ts
@@ -82,6 +82,7 @@ export {
   sessionFixtureName,
   sessionFixtureNames,
   sessionHeaderVersion,
+  writerSnapshotName,
   type PersistedSessionFile,
   type SessionFixtureFile,
 } from './session-files.ts'
diff --git a/packages/test-support/session-snapshot/src/normalize.ts b/packages/test-support/session-snapshot/src/normalize.ts
index 4f3768f3b7..c0624918f3 100644
--- a/packages/test-support/session-snapshot/src/normalize.ts
+++ b/packages/test-support/session-snapshot/src/normalize.ts
@@ -451,59 +451,21 @@ export function normalizeSessionSnapshots(
 }
 
 /**
- * Omit only generation-qualified operational provenance from expected-output comparison.
+ * Omit the artifact header generation after official migration for comparison.
+ * Delivery and captured-source generations retain their opaque recorded values.
  * @param rawLog - Session records or events as compact JSON lines.
- * @returns the same records without delivery or captured-source generation qualifiers.
+ * @returns the same records with only the Session header version omitted.
  */
 export function normalizeSessionFormatProvenance(rawLog: string): string {
   return rawLog.split('\n').map((line) => {
     if (line.trim().length === 0) return line
     const record = JSON.parse(line) as Record<string, unknown>
-    let changed = normalizeCapturedFormatProvenance(record)
-    if (record.type === 'session' && Object.hasOwn(record, 'version')) {
-      delete record.version
-      changed = true
-    }
-    if (record.type === 'session-log-deepseek/delivery-accepted'
-      && record.data !== null && typeof record.data === 'object' && !Array.isArray(record.data)) {
-      const data = { ...record.data as Record<string, unknown> }
-      if (Object.hasOwn(data, 'sessionFormatVersion')) {
-        delete data.sessionFormatVersion
-        record.data = data
-        changed = true
-      }
-    }
-    return changed ? JSON.stringify(record) : line
+    if (record.type !== 'session' || !Object.hasOwn(record, 'version')) return line
+    delete record.version
+    return JSON.stringify(record)
   }).join('\n')
 }
 
-/** Omit captured generations only from an actual current Message source position. */
-function normalizeCapturedFormatProvenance(event: Record<string, unknown>): boolean {
-  if (event.data === null || typeof event.data !== 'object' || Array.isArray(event.data)) return false
-  const data = event.data as Record<string, unknown>
-  const message = event.type === 'user/message'
-    ? data
-    : event.type === 'assistant/message' || event.type === 'tool/result'
-      ? data.message
-      : undefined
-  if (message === null || typeof message !== 'object' || Array.isArray(message)) return false
-  const source = (message as Record<string, unknown>).source
-  if (source === null || typeof source !== 'object' || Array.isArray(source)) return false
-  const record = source as Record<string, unknown>
-  if (record.kind !== 'session-reference' || record.form !== 'recall' || record.version !== 1
-    || !Array.isArray(record.references)) return false
-  let changed = false
-  for (const reference of record.references) {
-    if (reference === null || typeof reference !== 'object' || Array.isArray(reference)) continue
-    const captured = reference as Record<string, unknown>
-    if (Object.hasOwn(captured, 'capturedFormatVersion')) {
-      delete captured.capturedFormatVersion
-      changed = true
-    }
-  }
-  return changed
-}
-
 /** Whether a fixture declares a released Session format and therefore participates in migration burn-in. */
 function hasSessionFormatVersion(rawLog: string): boolean {
   const firstLine = rawLog.split(/\r?\n/).find(line => line.trim().length > 0)
diff --git a/packages/test-support/session-snapshot/src/session-files.ts b/packages/test-support/session-snapshot/src/session-files.ts
index bcb5609b52..8578abe416 100644
--- a/packages/test-support/session-snapshot/src/session-files.ts
+++ b/packages/test-support/session-snapshot/src/session-files.ts
@@ -46,6 +46,17 @@ export function sessionFixtureName(index: number, version: number): string {
   return `session${ordinal}${generation}.jsonl`
 }
 
+/**
+ * Name the native-writer oracle for a retained historical replay role.
+ * This expected output never participates in replay generation selection.
+ * @param index - Parent `0` or a positive child/ordinal slot.
+ * @returns The expected-output JSONL basename.
+ */
+export function writerSnapshotName(index: number): string {
+  nonNegativeSafeInteger(index, 'writer snapshot index')
+  return `writer${index === 0 ? '' : `.${index}`}.expected.jsonl`
+}
+
 /**
  * Parse one canonical recorded-session fixture filename.
  *
diff --git a/packages/test-support/session-snapshot/tests/normalize.spec.ts b/packages/test-support/session-snapshot/tests/normalize.spec.ts
index faf269309b..083781e417 100644
--- a/packages/test-support/session-snapshot/tests/normalize.spec.ts
+++ b/packages/test-support/session-snapshot/tests/normalize.spec.ts
@@ -658,78 +658,16 @@ describe('normalizeSessionSnapshot', () => {
       .toThrow('session snapshot must start with a session header')
   })
 
-  it('compares migrated and fresh delivery watermarks without changing their raw generation identity', () => {
-    const id = '11111111-2222-3333-4444-555555555555'
-    const session = (version: 0 | 1, sessionFormatVersion?: number): string => [
-      JSON.stringify({ type: 'session', version, id, createdAt: 0, delegationDepth: 0 }),
-      JSON.stringify({ type: 'turn/start', data: { turn: 1 } }),
-      JSON.stringify({
-        type: 'session-log-deepseek/delivery-accepted',
-        data: {
-          sessionId: id,
-          throughSeq: 0,
-          ...sessionFormatVersion === undefined ? {} : { sessionFormatVersion },
-        },
-      }),
-      JSON.stringify({ type: 'turn/end', data: { turn: 1, reason: { kind: 'completed' } } }),
-      '',
-    ].join('\n')
-
-    const migratedV0 = normalizeSessionSnapshots([session(0)], { sessionIds: [], cwd: '/unused' })
-    const freshV1 = normalizeSessionSnapshots([session(1, 1)], { sessionIds: [], cwd: '/unused' })
-
-    expect(migratedV0).toEqual(freshV1)
-    expect(freshV1[0]).not.toContain('"sessionFormatVersion"')
+  it('preserves delivery and captured-source generations after artifact migration', () => {
+    const event = (version: number): string => JSON.stringify({
+      type: 'session-log-deepseek/delivery-accepted',
+      data: { sessionId: 's', throughSeq: 4, sessionFormatVersion: version },
+    })
+    expect(normalizeSessionFormatProvenance(event(0))).toBe(event(0))
+    expect(normalizeSessionFormatProvenance(event(3))).not.toBe(normalizeSessionFormatProvenance(event(0)))
   })
 
-  it('compares migrated and fresh session-reference captures without hiding other source fields', () => {
-    const id = '11111111-2222-3333-4444-555555555555'
-    const sourceId = '22222222-3333-4444-5555-666666666666'
-    const messageId = '33333333-4444-4555-8666-777777777777'
-    const session = (version: 0 | 1, capturedFormatVersion?: number): string => [
-      JSON.stringify({ type: 'session', version, id, createdAt: 0, delegationDepth: 0 }),
-      JSON.stringify({ type: 'turn/start', data: { turn: 1 } }),
-      JSON.stringify({
-        type: 'user/message',
-        data: {
-          id: messageId,
-          role: 'user',
-          content: [{ type: 'text', text: 'remember' }],
-          source: {
-            kind: 'session-reference',
-            form: 'recall',
-            version: 1,
-            references: [{
-              sessionId: sourceId,
-              label: 'Source',
-              capturedThroughSeq: 0,
-              ...capturedFormatVersion === undefined ? {} : { capturedFormatVersion },
-              compacted: false,
-              originalMessages: 1,
-              retainedMessages: 1,
-              omittedMessages: 0,
-              omittedBytes: 0,
-              truncated: false,
-              inputIndex: 0,
-            }],
-          },
-        },
-        surfaceOp: 'append',
-      }),
-      JSON.stringify({ type: 'turn/end', data: { turn: 1, reason: { kind: 'completed' } } }),
-      '',
-    ].join('\n')
-
-    const migratedV0 = normalizeSessionSnapshots([session(0)], { sessionIds: [], cwd: '/unused' })
-    const freshV1 = normalizeSessionSnapshots([session(1, 1)], { sessionIds: [], cwd: '/unused' })
-
-    expect(migratedV0).toEqual(freshV1)
-    expect(freshV1[0]).toContain('"label":"Source"')
-    expect(freshV1[0]).toContain('"version":1')
-    expect(freshV1[0]).not.toContain('"capturedFormatVersion"')
-  })
-
-  it('removes generation qualifiers only from their exact provenance positions', () => {
+  it('preserves opaque generation qualifiers and their lookalikes', () => {
     const raw = [
       JSON.stringify({
         type: 'session',
@@ -782,14 +720,14 @@ describe('normalizeSessionSnapshot', () => {
       .split('\n')
       .map(line => JSON.parse(line) as Record<string, unknown>) ?? []
 
-    expect(delivery?.data).toEqual({ throughSeq: 21, otherVersion: 8 })
+    expect(delivery?.data).toEqual({ sessionFormatVersion: 1, throughSeq: 21, otherVersion: 8 })
     expect(captured?.data).toMatchObject({
       source: {
         references: [
           null,
           'opaque',
           [{ capturedFormatVersion: 6 }],
-          { otherVersion: 9 },
+          { capturedFormatVersion: 1, otherVersion: 9 },
         ],
       },
     })
diff --git a/packages/test-support/session-snapshot/tests/suite.spec.ts b/packages/test-support/session-snapshot/tests/suite.spec.ts
index f5ce6ad916..ebeb91e17f 100644
--- a/packages/test-support/session-snapshot/tests/suite.spec.ts
+++ b/packages/test-support/session-snapshot/tests/suite.spec.ts
@@ -15,6 +15,7 @@ import {
   sessionFixtureName,
   sessionFixtureNames,
   sessionHeaderVersion,
+  writerSnapshotName,
   stabilizeFixtureMessageIds,
   tokenizeSessionFixtureCwd,
   type HarvestedLog,
@@ -486,6 +487,19 @@ describe('shared snapshot content', () => {
   })
 })
 
+describe('writerSnapshotName', () => {
+  it('keeps native writer expectations outside historical replay selection', () => {
+    expect(writerSnapshotName(0)).toBe('writer.expected.jsonl')
+    expect(writerSnapshotName(2)).toBe('writer.2.expected.jsonl')
+    expect(sessionFixtureNames(['session.v1.jsonl', writerSnapshotName(0), writerSnapshotName(1)]))
+      .toEqual(['session.v1.jsonl'])
+  })
+
+  it.each([-1, -0, 0.5, Number.MAX_SAFE_INTEGER + 1])('rejects invalid role %s', (index) => {
+    expect(() => writerSnapshotName(index)).toThrow('writer snapshot index must be a non-negative safe integer')
+  })
+})
+
 describe('sessionFixtureNames', () => {
   it('selects the highest generation for each contiguous role while ignoring other files', () => {
     expect(sessionFixtureNames([
diff --git a/python/sdk/tests/test_smoke_model.py b/python/sdk/tests/test_smoke_model.py
index 4ff22908ed..a2e1b90be8 100644
--- a/python/sdk/tests/test_smoke_model.py
+++ b/python/sdk/tests/test_smoke_model.py
@@ -75,7 +75,7 @@ def test_mcp_smoke_accepts_the_external_server_result() -> None:
     )
 
 
-def test_snapshot_comparison_normalizes_only_session_generation_provenance() -> None:
+def test_snapshot_comparison_preserves_opaque_generation_provenance() -> None:
     normalize = SMOKE["normalize_session_format_comparison"]
     expected = {
         "header": {"type": "session", "version": 0, "otherVersion": 7},
@@ -104,8 +104,24 @@ def test_snapshot_comparison_normalizes_only_session_generation_provenance() ->
         },
     }
 
-    assert normalize(expected) == normalize(actual)
+    assert normalize(expected) != normalize(actual)
+    assert normalize(expected)["header"] == normalize(actual)["header"]
     assert normalize(expected)["header"]["otherVersion"] == 7
+    assert normalize(actual)["accepted"] == actual["accepted"]
+    assert normalize(actual)["source"] == actual["source"]
+
+
+def test_snapshot_value_scrubs_system_nodes_without_erasing_header_fields() -> None:
+    normalize = SMOKE["normalize_snapshot_value"]
+    system = {
+        "type": "system/message",
+        "data": {"message": {"role": "system", "content": [{"type": "text", "text": "prompt"}]}},
+    }
+    header = {"type": "request/header", "data": {"header": {"system": "unexpected"}}}
+    assert normalize(system, [])["data"]["message"]["content"] == [{"type": "text", "text": "{{system}}"}]
+    assert normalize(header, []) == header
+    empty = {"type": "system/message", "data": {"message": {"role": "system", "content": []}}}
+    assert normalize(empty, []) == empty
 
 
 def test_snapshot_value_normalizes_embedded_assistant_stream_timing() -> None:
diff --git a/scripts/smoke-python-runtime.py b/scripts/smoke-python-runtime.py
index 03babe7121..fb96b7bf71 100644
--- a/scripts/smoke-python-runtime.py
+++ b/scripts/smoke-python-runtime.py
@@ -126,7 +126,7 @@ ADVANCED_SNAPSHOT_DIRECTORY = (
     Path(__file__).resolve().parent / "snapshots" / "python-sdk-single-exe" / "advanced"
 )
 ADVANCED_SNAPSHOT_FILENAMES = (
-    "result.json", "session.v2.jsonl", "session.1.v2.jsonl", "session.2.v2.jsonl",
+    "result.json", "session.v3.jsonl", "session.1.v3.jsonl", "session.2.v3.jsonl",
 )
 MINIMAL_SNAPSHOT_DIRECTORY = (
     Path(__file__).resolve().parent / "snapshots" / "python-sdk-single-exe" / "minimal"
@@ -138,7 +138,7 @@ RESTART_SNAPSHOT_DIRECTORY = (
     Path(__file__).resolve().parent / "snapshots" / "python-sdk-single-exe" / "restart"
 )
 RESTART_SNAPSHOT_FILENAMES = (
-    "result.json", "requests.json", "session.1.v2.jsonl", "session.2.v2.jsonl",
+    "result.json", "requests.json", "session.1.v3.jsonl", "session.2.v3.jsonl",
 )
 MCP_SERVER_SCRIPT = """\
 import json
@@ -2139,19 +2139,6 @@ def normalize_session_format_comparison(
         normalized.pop("time", None)
     if source_session_version == 1 and normalized.get("type") == "assistant/message":
         normalized.pop("sourceEventSeqs", None)
-    if normalized.get("type") == "session-log-deepseek/delivery-accepted":
-        data = normalized.get("data")
-        if isinstance(data, dict):
-            data.pop("throughSeq", None)
-            data.pop("sessionFormatVersion", None)
-            data["sessionFormatVersion"] = SESSION_FORMAT_PROVENANCE
-    if normalized.get("kind") == "session-reference":
-        references = normalized.get("references")
-        if isinstance(references, list):
-            for reference in references:
-                if isinstance(reference, dict):
-                    reference.pop("capturedFormatVersion", None)
-                    reference["capturedFormatVersion"] = SESSION_FORMAT_PROVENANCE
     return normalized
 
 
diff --git a/snapshots/sdk/sdk.snapshot.ts b/snapshots/sdk/sdk.snapshot.ts
index fb913cb9fc..fbfaa4578a 100644
--- a/snapshots/sdk/sdk.snapshot.ts
+++ b/snapshots/sdk/sdk.snapshot.ts
@@ -39,6 +39,7 @@ import {
   systemPromptPrecedesRequests,
   sessionFixtureNames,
   sessionHeaderVersion,
+  writerSnapshotName,
   stabilizeFixtureMessageIds,
   stabilizeRefreshLog,
   tokenizeSessionFixtureCwd,
@@ -59,7 +60,7 @@ import {
   type RunResult,
   type SdkPromptContentBlock,
 } from '@deepseek-ai/dsh-sdk-client'
-import { prepareSessionEventNotificationsForComparison } from '@deepseek-ai/dsh-llm-replay'
+import { SESSION_FORMAT_VERSION } from '@deepseek-ai/dsh-session'
 
 const corpusRoot = fileURLToPath(new URL('../', import.meta.url))
 
@@ -235,7 +236,7 @@ async function persistedLogs(sessionsRoot: string): Promise<PersistedLog[]> {
   const files = await jsonlFiles(sessionsRoot)
   return Promise.all(files.map(async (path) => {
     const content = await readFile(path, 'utf8')
-    assertPersistedSessionVersion(basename(path), content)
+    expect(assertPersistedSessionVersion(basename(path), content), `${path}: current writer`).toBe(SESSION_FORMAT_VERSION)
     const header = JSON.parse(content.slice(0, content.indexOf('\n'))) as Record<string, unknown>
     return { path, content, header }
   }))
@@ -774,13 +775,20 @@ describe('TypeScript SDK snapshots over the jsonrpc runtime', () => {
       : it
     scenarioTest(`${mode}s ${scenario.name} through dsh --profile sdk`, async () => {
       const scenarioDir = scenario.dir
-      const notificationsExpectedPath = join(scenarioDir, 'notifications.expected.jsonl')
+      const retained = scenario.manifest.sessionFormat !== undefined
+      const notificationsExpectedPath = join(scenarioDir, retained ? 'notifications.current.expected.jsonl' : 'notifications.expected.jsonl')
       const resultExpectedPath = join(scenarioDir, 'result.expected.json')
       const hasWireGoldens = existsSync(notificationsExpectedPath) || existsSync(resultExpectedPath)
       const assertions = SDK_ASSERTIONS[scenario.name] ?? {}
       const writesSessionFixtures = writesCurrentSessionFixtures(scenario.manifest, sessionWriteMode)
 
       let files = await fixtureFiles(scenario)
+      const replayContents = await Promise.all(files.map(file => readFile(file, 'utf8')))
+      if (!recording && !refreshing) {
+        const writerFiles = (await readdir(scenarioDir)).filter(name => /^writer(?:\.[1-9]\d*)?\.expected\.jsonl$/u.test(name)).sort()
+        expect(writerFiles, 'native writer oracle inventory').toEqual(retained
+          ? files.map((_, index) => writerSnapshotName(index)).sort() : [])
+      }
       const { results, notifications, observedMethods, logs, initialWorkspace, finalWorkspace, cwd } = await runScenario(scenario)
       const ordered = orderLogs(
         logs,
@@ -789,7 +797,9 @@ describe('TypeScript SDK snapshots over the jsonrpc runtime', () => {
       )
       const actualContext = contextOf(ordered, cwd)
 
-      let expectedContents = await Promise.all(files.map(file => readFile(file, 'utf8')))
+      let expectedContents = retained && !refreshing
+        ? await Promise.all(files.map((_, index) => readFile(join(scenarioDir, writerSnapshotName(index)), 'utf8')))
+        : replayContents
 
       if (recording) {
         expectedContents = redactSessionSnapshotIds(stabilizeFixtureMessageIds(
@@ -798,7 +808,7 @@ describe('TypeScript SDK snapshots over the jsonrpc runtime', () => {
         ))
       }
 
-      if (refreshing && writesSessionFixtures) {
+      if (refreshing && (writesSessionFixtures || retained)) {
         const harvested = ordered.map((log): HarvestedLog => ({
           id: String(log.header.id),
           createdAt: Number(log.header.createdAt),
@@ -816,11 +826,10 @@ describe('TypeScript SDK snapshots over the jsonrpc runtime', () => {
         expectedContents = redactSessionSnapshotIds(stabilizeFixtureMessageIds(refreshed, expectedContents))
       }
 
-      if (writesSessionFixtures) {
-        const outputFiles = ordered.map((log, index) => join(scenarioDir, sessionFixtureName(
-          index,
-          sessionHeaderVersion(log.content, `harvested Session ${index}`),
-        )))
+      if (writesSessionFixtures || refreshing && retained) {
+        const outputFiles = ordered.map((log, index) => join(scenarioDir, retained
+          ? writerSnapshotName(index)
+          : sessionFixtureName(index, sessionHeaderVersion(log.content, `harvested Session ${index}`))))
         await Promise.all(expectedContents.map((stable, index) => writeFile(outputFiles[index] as string, stable)))
         files = outputFiles
         await writeHeaderSidecars(scenario, ordered, actualContext)
@@ -833,6 +842,14 @@ describe('TypeScript SDK snapshots over the jsonrpc runtime', () => {
       expect(redactSessionSnapshotIds(expectedContents), `${scenario.name}: identity redaction fixed point`)
         .toEqual(expectedContents)
 
+      if (retained) {
+        expect(await Promise.all((await fixtureFiles(scenario)).map(file => readFile(file, 'utf8'))),
+          'historical replay input remains unchanged').toEqual(replayContents)
+        for (const [index, content] of expectedContents.entries()) {
+          expect(sessionHeaderVersion(content, writerSnapshotName(index))).toBe(SESSION_FORMAT_VERSION)
+        }
+      }
+
       // Persisted transcripts match the committed fixtures.
       const expectedContext = contextOfContents(expectedContents)
       const actualSnapshots = normalizeSessionSnapshots(ordered.map(log => log.content), actualContext)
@@ -852,10 +869,10 @@ describe('TypeScript SDK snapshots over the jsonrpc runtime', () => {
         }
         const expectedNotifications = await readFile(notificationsExpectedPath, 'utf8')
         expect(
-          records(prepareSessionEventNotificationsForComparison(normalizedNotifications)),
+          records(normalizedNotifications),
           `${scenario.name}: notifications`,
         )
-          .toEqual(records(prepareSessionEventNotificationsForComparison(expectedNotifications)))
+          .toEqual(records(expectedNotifications))
         expect(normalizedResult).toBe(await readFile(resultExpectedPath, 'utf8'))
       }
 
diff --git a/snapshots/session/headless.snapshot.ts b/snapshots/session/headless.snapshot.ts
index 2ce8eb280e..4e41d8494d 100644
--- a/snapshots/session/headless.snapshot.ts
+++ b/snapshots/session/headless.snapshot.ts
@@ -35,6 +35,7 @@ import {
   systemPromptPrecedesRequests,
   sessionFixtureNames,
   sessionHeaderVersion,
+  writerSnapshotName,
   snapshotSpillRoot,
   stabilizeFixtureMessageIds,
   stabilizeRefreshLog,
@@ -168,7 +169,7 @@ async function persistedSessions(cwd: string): Promise<SessionLog[]> {
   const files = latestPersistedSessionPaths(await readdir(root, { recursive: true }))
   const logs = await Promise.all(files.map(async (file): Promise<SessionLog> => {
     const content = await readFile(join(root, file), 'utf8')
-    assertPersistedSessionVersion(basename(file), content)
+    expect(assertPersistedSessionVersion(basename(file), content), `${file}: current writer`).toBe(SESSION_FORMAT_VERSION)
     return { content, header: headerOf(content) }
   }))
   return logs.sort((left, right) => {
@@ -202,10 +203,9 @@ async function writeSessionFixtures(
   existing: readonly string[],
   ctx: NormalizeContext,
 ): Promise<string[]> {
-  const names = actualLogs.map((log, index) => sessionFixtureName(
-    index,
-    sessionHeaderVersion(log.content, `harvested Session ${index}`),
-  ))
+  const names = actualLogs.map((log, index) => scenario.manifest.sessionFormat === undefined
+    ? sessionFixtureName(index, sessionHeaderVersion(log.content, `harvested Session ${index}`))
+    : writerSnapshotName(index))
   const prior = names.map((_, index) => existing[index] ?? '')
   const replacements = mode === 'refresh'
     ? refreshFixtureReplacements(actualLogs.map(harvested), prior)
@@ -535,36 +535,6 @@ function pinOf(scenario: HeadlessScenario): HeadlessScenario {
   return pin
 }
 
-/** Compare retained prompt-in-header semantics without weakening current-writer snapshots. */
-function historicalComparison(log: string): string {
-  const current = prepareSessionSnapshotFixtureForComparison(log)
-  const events = parseSessionLog(current)
-  const retained = events.filter(event => event.type !== 'system/message')
-  const positions = new Map(retained.map((event, index) => [Number(event.seq), index]))
-  let system: string | undefined
-  const output: JsonObject[] = []
-  for (const event of events) {
-    if (event.type === 'system/message') {
-      system = event.data.message.content.flatMap(block => block.type === 'text' ? [block.text] : []).join('')
-      continue
-    }
-    const row = JSON.parse(JSON.stringify(event)) as JsonObject
-    row.seq = positions.get(Number(event.seq))
-    const data = row.data as JsonObject
-    if (event.type === 'request/header' && system !== undefined) {
-      data.header = { ...data.header as JsonObject, system }
-    }
-    if (Array.isArray(row.sourceEventSeqs)) {
-      row.sourceEventSeqs = row.sourceEventSeqs.map(seq => positions.get(Number(seq)))
-    }
-    if (event.type === 'session/title' && Array.isArray(data.messageSeqs)) {
-      data.messageSeqs = data.messageSeqs.map(seq => positions.get(Number(seq)))
-    }
-    output.push(row)
-  }
-  return [records(current)[0], ...output].map(row => JSON.stringify(row)).join('\n') + '\n'
-}
-
 /** Require successful verification and the complete canonical event before refresh can write a fixture. */
 async function verifySessionQuerySpill(log: string): Promise<void> {
   const events = parseSessionLog(log)
@@ -653,30 +623,6 @@ describe('headless recorded-session snapshots', () => {
     }
   })
 
-  it('preserves prompt, request, and citation differences in historical comparisons', async () => {
-    const fixture = await readFile(join(snapshotsRoot, 'tool-call-turn/session.v2.jsonl'), 'utf8')
-    const baseline = records(historicalComparison(fixture))
-    const changed = (mutate: (rows: JsonObject[]) => void): JsonObject[] => {
-      const rows = records(fixture)
-      mutate(rows)
-      return records(historicalComparison(rows.map(row => JSON.stringify(row)).join('\n') + '\n'))
-    }
-    expect(baseline.find(row => row.type === 'request/header')?.data).toMatchObject({ header: { system: '{{system}}' } })
-    expect(changed(rows => {
-      const data = rows.find(row => row.type === 'system/message')?.data as JsonObject
-      const message = data.message as JsonObject
-      message.content = [{ type: 'text', text: 'wrong system prompt' }]
-    })).not.toEqual(baseline)
-    expect(changed(rows => {
-      const header = rows.find(row => row.type === 'request/header')?.data as JsonObject
-      ;((header.header as JsonObject).config as JsonObject).model = 'different-model'
-    })).not.toEqual(baseline)
-    expect(() => changed(rows => {
-      const title = rows.find(row => row.type === 'session/title')?.data as JsonObject
-      title.messageSeqs = [0]
-    })).toThrow('messageSeqs must cite earlier human user/message events')
-  })
-
   it('recognizes the supported OS-assigned listener forms', () => {
     expect(listenerPortViolations('accepted.mjs', [
       "server.listen(0, '127.0.0.1')",
@@ -716,7 +662,7 @@ describe('headless recorded-session snapshots', () => {
   it('keeps packed chunk rows logically equal to their unpacked recording', async () => {
     const sourceDir = join(snapshotsRoot, 'hook-cc-pretool-deny')
     const packedDir = join(snapshotsRoot, 'packed-chunks')
-    const source = await readFile(join(sourceDir, await primaryFixtureFile(sourceDir)), 'utf8')
+    const source = await readFile(join(sourceDir, 'session.jsonl'), 'utf8')
     const packed = await readFile(join(packedDir, await primaryFixtureFile(packedDir)), 'utf8')
     const rowTypes = records(packed).flatMap((record) => {
       const type = record.type
@@ -751,15 +697,10 @@ describe('headless recorded-session snapshots', () => {
         }
       }
       if (cloned.type === 'hook/result') delete cloned.data?.durationMs
-      if (cloned.type === 'session/title') delete (cloned.data as { messageSeqs?: unknown })?.messageSeqs
-      // Positional seq references shift with the `system/message` node the
-      // retained packed generation cannot invent; both sides cite their own
-      // step's Assistant settlement, so the citation is not the comparison.
-      delete (cloned as { sourceEventSeqs?: unknown }).sourceEventSeqs
       return cloned
     }
     const logical = (fixture: string): unknown[] => {
-      const current = historicalComparison(fixture)
+      const current = prepareSessionSnapshotFixtureForComparison(fixture)
       return [
         records(current)[0],
         ...parseSessionLog(current).map(withoutVolatileMessage),
@@ -1032,12 +973,22 @@ describe('headless recorded-session snapshots', () => {
       expect(result.stdout).toBe(`${finalTextFromSession(fixtures[0] as string)}\n`)
       expect(result.stderr).toBe(expectedStderr)
       expect(actualLogs, `${scenario.name}: persisted session count`).toHaveLength(fixtures.length)
-      const fixtureContext = contextOf(fixtures)
-      const comparison = scenario.manifest.sessionFormat === undefined
-        ? (log: string): string => log
-        : (log: string): string => historicalComparison(scrubSystemPrompts(log))
-      const actualSnapshots = normalizeSessionSnapshots(actualLogs.map(log => comparison(log.content)), actualContext)
-      const expectedSnapshots = normalizeSessionSnapshots(fixtures.map(comparison), fixtureContext)
+      const writerFiles = (await readdir(scenario.dir)).filter(name => /^writer(?:\.[1-9]\d*)?\.expected\.jsonl$/u.test(name)).sort()
+      if (mode === 'replay') {
+        expect(writerFiles, 'native writer oracle inventory').toEqual(scenario.manifest.sessionFormat === undefined
+          ? [] : fixtures.map((_, index) => writerSnapshotName(index)).sort())
+      }
+      let expected = fixtures
+      if (scenario.manifest.sessionFormat !== undefined) {
+        if (mode === 'refresh') await writeSessionFixtures(scenario, actualLogs, fixtures, actualContext)
+        expected = await Promise.all(fixtures.map((_, index) => readFile(join(scenario.dir, writerSnapshotName(index)), 'utf8')))
+        for (const [index, content] of expected.entries()) {
+          expect(sessionHeaderVersion(content, writerSnapshotName(index))).toBe(SESSION_FORMAT_VERSION)
+        }
+        expect(await fixtureSessions(scenario), 'historical replay input remains unchanged').toEqual(fixtures)
+      }
+      const actualSnapshots = normalizeSessionSnapshots(actualLogs.map(log => log.content), actualContext)
+      const expectedSnapshots = normalizeSessionSnapshots(expected, contextOf(expected))
       for (const [index, actual] of actualSnapshots.entries()) {
         expect(records(actual), `${scenario.name}: session ${index}`).toEqual(records(expectedSnapshots[index] as string))
       }