diff --git a/src/main/codex/codex-session-backfill-audit-pass.ts b/src/main/codex/codex-session-backfill-audit-pass.ts
new file mode 100644
index 00000000000..5f7e8329dc2
--- /dev/null
+++ b/src/main/codex/codex-session-backfill-audit-pass.ts
@@ -0,0 +1,93 @@
+import type { Stats } from 'node:fs'
+import { lstat } from 'node:fs/promises'
+import {
+  appendCodexSessionHealAuditRecord,
+  createCodexSessionBackfillAuditWriter,
+  createCodexSessionBackfillFileEventId,
+  readCodexSessionBackfillAuditCoverage,
+  recordExistingCodexSessionForHeal,
+  type CodexSessionBackfillAuditWriter
+} from './codex-session-backfill-audit'
+import type { CodexSessionBackfillSummary } from './codex-session-backfill-types'
+
+export type CodexSessionBackfillAuditPass = {
+  appendRecord: CodexSessionBackfillAuditWriter
+  recordExisting(
+    summary: CodexSessionBackfillSummary,
+    source: string,
+    target: string,
+    targetStat: Stats | null
+  ): Promise<void>
+  recordPublished(
+    summary: CodexSessionBackfillSummary,
+    action: 'hardlink' | 'copy',
+    source: string,
+    target: string
+  ): Promise<void>
+  finish(summary: CodexSessionBackfillSummary): Promise<void>
+}
+
+export async function createCodexSessionBackfillAuditPass(
+  auditLogPath: string
+): Promise<CodexSessionBackfillAuditPass> {
+  const coverage = await readCodexSessionBackfillAuditCoverage(auditLogPath)
+  const writeAuditRecord = createCodexSessionBackfillAuditWriter(auditLogPath)
+  let auditChanged = false
+  const appendRecord: CodexSessionBackfillAuditWriter = async (record) => {
+    const appended = await writeAuditRecord(record)
+    auditChanged ||= appended
+    return appended
+  }
+
+  return {
+    appendRecord,
+    async recordExisting(summary, source, target, targetStat): Promise<void> {
+      const fileEventId = targetStat
+        ? createCodexSessionBackfillFileEventId(target, targetStat)
+        : undefined
+      if (fileEventId && coverage.fileEventIds.has(fileEventId)) {
+        summary.skippedExistingFiles += 1
+        return
+      }
+      if (
+        await recordExistingCodexSessionForHeal(appendRecord, summary, source, target, fileEventId)
+      ) {
+        if (fileEventId) {
+          coverage.fileEventIds.add(fileEventId)
+        }
+      }
+    },
+    async recordPublished(summary, action, source, target): Promise<void> {
+      const targetStat = await readCodexSessionTargetStat(target)
+      const fileEventId = targetStat
+        ? createCodexSessionBackfillFileEventId(target, targetStat)
+        : undefined
+      if (
+        await appendCodexSessionHealAuditRecord(appendRecord, summary, {
+          action,
+          source,
+          target,
+          ...(fileEventId ? { fileEventId } : {})
+        })
+      ) {
+        if (fileEventId) {
+          coverage.fileEventIds.add(fileEventId)
+        }
+      }
+    },
+    async finish(summary): Promise<void> {
+      if (auditChanged || !coverage.hasRunSummary) {
+        await appendRecord({ action: 'run-summary', ...summary })
+      }
+    }
+  }
+}
+
+/** A broken symlink at the target still counts as taken. */
+export async function readCodexSessionTargetStat(entryPath: string): Promise<Stats | null> {
+  try {
+    return await lstat(entryPath)
+  } catch {
+    return null
+  }
+}
diff --git a/src/main/codex/codex-session-backfill-audit.ts b/src/main/codex/codex-session-backfill-audit.ts
index c4740b95572..66fe7717130 100644
--- a/src/main/codex/codex-session-backfill-audit.ts
+++ b/src/main/codex/codex-session-backfill-audit.ts
@@ -1,10 +1,20 @@
-import { randomUUID } from 'node:crypto'
+import { createHash, randomUUID } from 'node:crypto'
+import { createReadStream, type Stats } from 'node:fs'
 import { appendFile, mkdir } from 'node:fs/promises'
 import { dirname } from 'node:path'
+import { createInterface } from 'node:readline'
+import { normalizeRuntimePathForComparison } from '../../shared/cross-platform-path'
 import type { CodexSessionBackfillSummary } from './codex-session-backfill-types'
 
 export type CodexSessionBackfillAuditWriter = (record: Record<string, unknown>) => Promise<boolean>
 
+export type CodexSessionBackfillAuditCoverage = {
+  fileEventIds: Set<string>
+  hasRunSummary: boolean
+}
+
+const HEAL_AUDIT_ACTIONS = new Set(['hardlink', 'copy', 'existing'])
+
 export function createCodexSessionBackfillAuditWriter(
   auditLogPath: string
 ): CodexSessionBackfillAuditWriter {
@@ -48,28 +58,85 @@ export function createCodexSessionBackfillAuditWriter(
   }
 }
 
+export async function readCodexSessionBackfillAuditCoverage(
+  auditLogPath: string
+): Promise<CodexSessionBackfillAuditCoverage> {
+  const coverage: CodexSessionBackfillAuditCoverage = {
+    fileEventIds: new Set<string>(),
+    hasRunSummary: false
+  }
+  const input = createReadStream(auditLogPath, { encoding: 'utf-8' })
+  const lines = createInterface({ input, crlfDelay: Infinity })
+  try {
+    for await (const raw of lines) {
+      try {
+        const parsed: unknown = JSON.parse(raw)
+        if (!parsed || typeof parsed !== 'object' || Array.isArray(parsed)) {
+          continue
+        }
+        const record = parsed as Record<string, unknown>
+        coverage.hasRunSummary ||= record.action === 'run-summary'
+        if (
+          typeof record.action === 'string' &&
+          HEAL_AUDIT_ACTIONS.has(record.action) &&
+          typeof record.fileEventId === 'string'
+        ) {
+          coverage.fileEventIds.add(record.fileEventId)
+        }
+      } catch {
+        // Torn audit tails are quarantined by the writer's leading newline.
+      }
+    }
+  } catch (error) {
+    if (!isNotFoundError(error)) {
+      throw error
+    }
+  }
+  return coverage
+}
+
+export function createCodexSessionBackfillFileEventId(targetPath: string, stat: Stats): string {
+  const stableFileIdentity =
+    stat.ino !== 0 || stat.birthtimeMs !== 0
+      ? `${stat.dev}\0${stat.ino}\0${stat.birthtimeMs}`
+      : `${stat.size}\0${stat.mtimeMs}\0${stat.ctimeMs}`
+  return createHash('sha256')
+    .update(normalizeRuntimePathForComparison(targetPath))
+    .update('\0')
+    .update(stableFileIdentity)
+    .digest('hex')
+}
+
 export async function appendCodexSessionHealAuditRecord(
   writer: CodexSessionBackfillAuditWriter,
   summary: CodexSessionBackfillSummary,
   record: Record<string, unknown>
-): Promise<void> {
-  if (!(await writer(record))) {
+): Promise<boolean> {
+  const appended = await writer(record)
+  if (!appended) {
     summary.failedHealAuditRecords += 1
   }
+  return appended
 }
 
 export async function recordExistingCodexSessionForHeal(
   writer: CodexSessionBackfillAuditWriter,
   summary: CodexSessionBackfillSummary,
   source: string,
-  target: string
-): Promise<void> {
+  target: string,
+  fileEventId?: string
+): Promise<boolean> {
   summary.skippedExistingFiles += 1
   // Why: this also recovers a rollout installed before a crash or audit
   // failure; thread/read is idempotent for a pre-existing real-home file.
-  await appendCodexSessionHealAuditRecord(writer, summary, {
+  return appendCodexSessionHealAuditRecord(writer, summary, {
     action: 'existing',
     source,
-    target
+    target,
+    ...(fileEventId ? { fileEventId } : {})
   })
 }
+
+function isNotFoundError(error: unknown): boolean {
+  return (error as NodeJS.ErrnoException | null)?.code === 'ENOENT'
+}
diff --git a/src/main/codex/codex-session-backfill.test.ts b/src/main/codex/codex-session-backfill.test.ts
index f8427e8b40f..b1ef73d8edd 100644
--- a/src/main/codex/codex-session-backfill.test.ts
+++ b/src/main/codex/codex-session-backfill.test.ts
@@ -140,6 +140,7 @@ import {
   resolveCodexSessionBackfillPaths,
   startCodexSessionBackfillInBackground
 } from './codex-session-backfill'
+import { invalidateCodexSessionBackfillMarker } from './codex-session-backfill-marker'
 
 let fakeHomeDir: string
 let userDataDir: string
@@ -168,19 +169,29 @@ function writeManagedSession(relativePath: string, contents: string): string {
   return filePath
 }
 
-function readAuditActions(): string[] {
+type BackfillAuditRecord = {
+  action: string
+  target?: string
+  fileEventId?: string
+}
+
+function readBackfillAuditRecords(): BackfillAuditRecord[] {
   return readFileSync(getAuditLogPath(), 'utf-8')
     .split('\n')
     .filter(Boolean)
     .flatMap((line) => {
       try {
-        return [(JSON.parse(line) as { action: string }).action]
+        return [JSON.parse(line) as BackfillAuditRecord]
       } catch {
         return []
       }
     })
 }
 
+function readAuditActions(): string[] {
+  return readBackfillAuditRecords().map((record) => record.action)
+}
+
 beforeEach(() => {
   fsMockState.failLink = false
   fsMockState.failInstallLink = false
@@ -496,6 +507,74 @@ describe('startCodexSessionBackfillInBackground', () => {
     ).toBe(false)
   })
 
+  it('keeps repeated launch invalidations audit-stable', async () => {
+    writeManagedSession(join('2026', '05', '26', 'rollout-a.jsonl'), '{"id":"a"}\n')
+
+    const first = await startCodexSessionBackfillInBackground()
+    expect(first).toMatchObject({ linkedFiles: 1, failedHealAuditRecords: 0 })
+    const firstAudit = readFileSync(getAuditLogPath(), 'utf-8')
+
+    for (let pass = 0; pass < 2; pass += 1) {
+      invalidateCodexSessionBackfillMarker(getMarkerPath())
+      const repeated = await startCodexSessionBackfillInBackground()
+      expect(repeated).toMatchObject({
+        linkedFiles: 0,
+        copiedFiles: 0,
+        skippedExistingFiles: 1,
+        failedHealAuditRecords: 0
+      })
+      expect(readFileSync(getAuditLogPath(), 'utf-8')).toBe(firstAudit)
+    }
+
+    const fileRecords = readBackfillAuditRecords().filter((record) =>
+      ['hardlink', 'copy', 'existing'].includes(record.action)
+    )
+    expect(fileRecords).toEqual([
+      expect.objectContaining({ action: 'hardlink', fileEventId: expect.any(String) })
+    ])
+  })
+
+  it('recovers a post-install audit interruption without duplicating prior events', async () => {
+    const firstRelativePath = join('2026', '05', '26', 'rollout-a.jsonl')
+    const secondRelativePath = join('2026', '05', '26', 'rollout-b.jsonl')
+    writeManagedSession(firstRelativePath, '{"id":"a"}\n')
+    await startCodexSessionBackfillInBackground()
+
+    invalidateCodexSessionBackfillMarker(getMarkerPath())
+    writeManagedSession(secondRelativePath, '{"id":"b"}\n')
+    fsMockState.failAuditWrites = true
+
+    const interrupted = await startCodexSessionBackfillInBackground()
+
+    expect(interrupted).toMatchObject({ linkedFiles: 1, failedHealAuditRecords: 1 })
+    expect(existsSync(getMarkerPath())).toBe(false)
+    expect(
+      readBackfillAuditRecords().filter((record) =>
+        ['hardlink', 'copy', 'existing'].includes(record.action)
+      )
+    ).toHaveLength(1)
+
+    fsMockState.failAuditWrites = false
+    const recovered = await startCodexSessionBackfillInBackground()
+
+    expect(recovered).toMatchObject({
+      linkedFiles: 0,
+      skippedExistingFiles: 2,
+      failedHealAuditRecords: 0
+    })
+    expect(existsSync(getMarkerPath())).toBe(true)
+    const recoveredFileRecords = readBackfillAuditRecords().filter((record) =>
+      ['hardlink', 'copy', 'existing'].includes(record.action)
+    )
+    expect(recoveredFileRecords).toHaveLength(2)
+    expect(new Set(recoveredFileRecords.map((record) => record.target))).toEqual(
+      new Set([
+        join(getSystemSessionsRoot(), firstRelativePath),
+        join(getSystemSessionsRoot(), secondRelativePath)
+      ])
+    )
+  })
+
   it('self-heals a zero-file marker when managed rollouts appear later', async () => {
     const empty = await startCodexSessionBackfillInBackground()
     expect(empty).toMatchObject({ scannedFiles: 0, linkedFiles: 0 })
diff --git a/src/main/codex/codex-session-backfill.ts b/src/main/codex/codex-session-backfill.ts
index 403c4135b52..018e6da38d0 100644
--- a/src/main/codex/codex-session-backfill.ts
+++ b/src/main/codex/codex-session-backfill.ts
@@ -6,11 +6,10 @@ import {
   getSystemCodexHomePath
 } from './codex-home-paths'
 import {
-  appendCodexSessionHealAuditRecord,
-  createCodexSessionBackfillAuditWriter,
-  recordExistingCodexSessionForHeal,
-  type CodexSessionBackfillAuditWriter
-} from './codex-session-backfill-audit'
+  createCodexSessionBackfillAuditPass,
+  readCodexSessionTargetStat,
+  type CodexSessionBackfillAuditPass
+} from './codex-session-backfill-audit-pass'
 import {
   copySessionFileWithoutOverwrite,
   isAtomicNoReplaceUnsupportedError
@@ -135,13 +134,9 @@ export async function backfillManagedCodexSessionsIntoSystemHome(
     failedFiles: 0,
     failedHealAuditRecords: 0
   }
-  const appendAuditRecord = createCodexSessionBackfillAuditWriter(paths.auditLogPath)
+  const auditPass = await createCodexSessionBackfillAuditPass(paths.auditLogPath)
   const ensuredTargetDirectories = new Set<string>()
-  const managedSessionsRootExists = await checkManagedSessionsRoot(
-    paths,
-    summary,
-    appendAuditRecord
-  )
+  const managedSessionsRootExists = await checkManagedSessionsRoot(paths, summary, auditPass)
   if (managedSessionsRootExists) {
     for await (const managedSessionFilePath of listCodexSessionJsonlFilesIncrementally(
       paths.managedSessionsRoot,
@@ -150,7 +145,7 @@ export async function backfillManagedCodexSessionsIntoSystemHome(
         // Why: a partial walk must remain retryable; otherwise an unreadable
         // date directory would be silently omitted behind a completion marker.
         summary.failedDirectories += 1
-        await appendAuditRecord({
+        await auditPass.appendRecord({
           action: 'scan-failed',
           source: directoryPath,
           error: describeError(error)
@@ -174,13 +169,13 @@ export async function backfillManagedCodexSessionsIntoSystemHome(
         paths,
         managedSessionFilePath,
         summary,
-        appendAuditRecord,
-        ensuredTargetDirectories
+        ensuredTargetDirectories,
+        auditPass
       )
     }
   }
   summary.stopped ||= options.shouldStop?.() === true
-  await appendAuditRecord({ action: 'run-summary', ...summary })
+  await auditPass.finish(summary)
   // Why: opt-out can land while the async summary append is pending; carry it
   // back to the marker gate so a managed launch cannot be hidden by stale completion.
   summary.stopped ||= options.shouldStop?.() === true
@@ -190,7 +185,7 @@ export async function backfillManagedCodexSessionsIntoSystemHome(
 async function checkManagedSessionsRoot(
   paths: CodexSessionBackfillPaths,
   summary: CodexSessionBackfillSummary,
-  appendAuditRecord: CodexSessionBackfillAuditWriter
+  auditPass: CodexSessionBackfillAuditPass
 ): Promise<boolean> {
   try {
     await lstat(paths.managedSessionsRoot)
@@ -202,7 +197,7 @@ async function checkManagedSessionsRoot(
     // Why: existsSync collapses access failures into "missing," which could
     // permanently hide sessions behind an incorrect completion marker.
     summary.failedDirectories += 1
-    await appendAuditRecord({
+    await auditPass.appendRecord({
       action: 'scan-failed',
       source: paths.managedSessionsRoot,
       error: describeError(error)
@@ -229,8 +224,8 @@ async function backfillOneManagedSessionFile(
   paths: CodexSessionBackfillPaths,
   managedSessionFilePath: string,
   summary: CodexSessionBackfillSummary,
-  appendAuditRecord: CodexSessionBackfillAuditWriter,
-  ensuredTargetDirectories: Set<string>
+  ensuredTargetDirectories: Set<string>,
+  auditPass: CodexSessionBackfillAuditPass
 ): Promise<void> {
   if (await isSymbolicLink(managedSessionFilePath)) {
     // Why: bridge-created symlinks already point at a file in the user's own
@@ -240,12 +235,13 @@ async function backfillOneManagedSessionFile(
   }
   const relativePath = relative(paths.managedSessionsRoot, managedSessionFilePath)
   const systemSessionFilePath = join(paths.systemSessionsRoot, relativePath)
-  if (await pathEntryExists(systemSessionFilePath)) {
-    await recordExistingCodexSessionForHeal(
-      appendAuditRecord,
+  const existingTargetStat = await readCodexSessionTargetStat(systemSessionFilePath)
+  if (existingTargetStat) {
+    await auditPass.recordExisting(
       summary,
       managedSessionFilePath,
-      systemSessionFilePath
+      systemSessionFilePath,
+      existingTargetStat
     )
     return
   }
@@ -260,20 +256,21 @@ async function backfillOneManagedSessionFile(
     }
     await link(managedSessionFilePath, systemSessionFilePath)
     summary.linkedFiles += 1
-    await appendCodexSessionHealAuditRecord(appendAuditRecord, summary, {
-      action: 'hardlink',
-      source: managedSessionFilePath,
-      target: systemSessionFilePath
-    })
+    await auditPass.recordPublished(
+      summary,
+      'hardlink',
+      managedSessionFilePath,
+      systemSessionFilePath
+    )
   } catch (linkError) {
     if (isExistsError(linkError)) {
       // Why: another window can publish the target after our existence probe;
       // enqueue it here too in case that writer died before its audit append.
-      await recordExistingCodexSessionForHeal(
-        appendAuditRecord,
+      await auditPass.recordExisting(
         summary,
         managedSessionFilePath,
-        systemSessionFilePath
+        systemSessionFilePath,
+        await readCodexSessionTargetStat(systemSessionFilePath)
       )
       return
     }
@@ -285,24 +282,25 @@ async function backfillOneManagedSessionFile(
       // truncated rollout, then installed without overwriting collisions.
       await copySessionFileWithoutOverwrite(managedSessionFilePath, systemSessionFilePath)
       summary.copiedFiles += 1
-      await appendCodexSessionHealAuditRecord(appendAuditRecord, summary, {
-        action: 'copy',
-        source: managedSessionFilePath,
-        target: systemSessionFilePath
-      })
+      await auditPass.recordPublished(
+        summary,
+        'copy',
+        managedSessionFilePath,
+        systemSessionFilePath
+      )
     } catch (copyError) {
       if (isExistsError(copyError)) {
-        await recordExistingCodexSessionForHeal(
-          appendAuditRecord,
+        await auditPass.recordExisting(
           summary,
           managedSessionFilePath,
-          systemSessionFilePath
+          systemSessionFilePath,
+          await readCodexSessionTargetStat(systemSessionFilePath)
         )
         return
       }
       if (isAtomicNoReplaceUnsupportedError(copyError)) {
         summary.skippedUnsupportedFilesystemFiles += 1
-        await appendAuditRecord({
+        await auditPass.appendRecord({
           action: 'copy-unsupported',
           source: managedSessionFilePath,
           target: systemSessionFilePath
@@ -310,7 +308,7 @@ async function backfillOneManagedSessionFile(
         return
       }
       summary.failedFiles += 1
-      await appendAuditRecord({
+      await auditPass.appendRecord({
         action: 'failed',
         source: managedSessionFilePath,
         target: systemSessionFilePath,
@@ -329,16 +327,6 @@ async function isSymbolicLink(filePath: string): Promise<boolean> {
   }
 }
 
-/** Existence via lstat so a broken symlink at the target still counts as taken. */
-async function pathEntryExists(entryPath: string): Promise<boolean> {
-  try {
-    await lstat(entryPath)
-    return true
-  } catch {
-    return false
-  }
-}
-
 function isExistsError(error: unknown): boolean {
   return (error as NodeJS.ErrnoException | null)?.code === 'EEXIST'
 }
diff --git a/src/main/codex/codex-session-index-heal.test.ts b/src/main/codex/codex-session-index-heal.test.ts
index 861c7f72b4e..efd5eac317a 100644
--- a/src/main/codex/codex-session-index-heal.test.ts
+++ b/src/main/codex/codex-session-index-heal.test.ts
@@ -232,7 +232,7 @@ describe('runCodexSessionIndexHeal', () => {
     expect(marker.healedThreads).toBe(3)
   })
 
-  it('is a no-op when the marker matches the audit ledger size', async () => {
+  it('keeps second and later passes cheap when the audit ledger is unchanged', async () => {
     const rig = createHealRig({
       auditedThreads: [{ stamp: '2026-07-01T10-00-00', id: threadId('1') }]
     })
@@ -245,8 +245,13 @@ describe('runCodexSessionIndexHeal', () => {
       buildInvocation: rig.buildInvocation,
       interBatchDelayMs: 0
     })
+    const third = await runCodexSessionIndexHeal(rig.paths, {
+      buildInvocation: rig.buildInvocation,
+      interBatchDelayMs: 0
+    })
     expect(second.outcome).toBe('up-to-date')
-    // One spawn from the first run only — the no-op run must not hit the CLI.
+    expect(third.outcome).toBe('up-to-date')
+    // One spawn from the first run only — no-op runs must not hit the CLI.
     expect(rig.readLog().serverStarts).toBe(1)
   })