diff --git a/src/main/agent-hooks/hooks-json-read.ts b/src/main/agent-hooks/hooks-json-read.ts
index e2c8743cab0..97ca220c354 100644
--- a/src/main/agent-hooks/hooks-json-read.ts
+++ b/src/main/agent-hooks/hooks-json-read.ts
@@ -1,4 +1,5 @@
-import { existsSync, readFileSync } from 'node:fs'
+import { readFileSync } from 'node:fs'
+import { isDefinitiveAbsence } from '../../shared/definitive-filesystem-absence'
 import type { HooksConfig } from './installer-utils'
 
 export function isPlainObject(value: unknown): value is Record<string, unknown> {
@@ -26,16 +27,17 @@ export function parseHooksJsonText(raw: string): HooksConfig | null {
 // bytes it was derived from; the raw snapshot and the parse must come from one
 // read or a concurrent save can slip between them unnoticed.
 export function readHooksJsonWithRaw(configPath: string): HooksJsonSnapshot {
-  if (!existsSync(configPath)) {
-    return { raw: null, config: {} }
-  }
-  let raw: string
+  // Why: the read arm below already separates "no hooks configured" from "could
+  // not read", but the `existsSync` arm in front of it did not — it returned a
+  // VALID EMPTY config for a file that merely could not be opened, and the
+  // installer then wrote generated hooks over it. One read classifies both, and
+  // closes the TOCTOU window between the two calls.
   try {
-    raw = readFileSync(configPath, 'utf-8')
-  } catch {
-    return { raw: null, config: null }
+    const raw = readFileSync(configPath, 'utf-8')
+    return { raw, config: parseHooksJsonText(raw) }
+  } catch (error) {
+    return isDefinitiveAbsence(error) ? { raw: null, config: {} } : { raw: null, config: null }
   }
-  return { raw, config: parseHooksJsonText(raw) }
 }
 
 export function readHooksJson(configPath: string): HooksConfig | null {
diff --git a/src/main/codex/codex-pane-account-registry.ts b/src/main/codex/codex-pane-account-registry.ts
index 39853471683..faa8dd87c0d 100644
--- a/src/main/codex/codex-pane-account-registry.ts
+++ b/src/main/codex/codex-pane-account-registry.ts
@@ -1,4 +1,5 @@
 import { mkdirSync, readFileSync, renameSync, rmSync, writeFileSync } from 'node:fs'
+import { isDefinitiveAbsence } from '../../shared/definitive-filesystem-absence'
 import { dirname, join } from 'node:path'
 import { getOrcaUserDataPath } from './codex-home-paths'
 import type {
@@ -51,22 +52,47 @@ function getRegistryPath(): string {
   return join(getOrcaUserDataPath(), 'codex-pane-accounts.json')
 }
 
-function readRegistry(): RegistryFile {
+/**
+ * `null` means the registry could not be READ. That is not the same as "no
+ * panes are attributed", and it must never be cached: the old `catch { return
+ * null }` collapsed both into an empty registry, so one unreadable read erased
+ * every pane's account attribution AND pinned that erasure in `cachedRegistry`
+ * for the rest of the process, surviving the file becoming readable again.
+ */
+function readRegistryOrNull(): RegistryFile | null {
   if (cachedRegistry) {
     return cachedRegistry
   }
-  cachedRegistry = parseRegistry(readRegistryFile())
+  let rawRegistry: string
+  try {
+    rawRegistry = readFileSync(getRegistryPath(), 'utf-8')
+  } catch (error) {
+    if (!isDefinitiveAbsence(error)) {
+      return null
+    }
+    cachedRegistry = parseRegistry(null)
+    return cachedRegistry
+  }
+  // Why: a corrupt registry still degrades to empty and IS cached — rebuilding
+  // unparseable state is the intent, and re-reading it every call would only
+  // repeat the parse failure.
+  cachedRegistry = parseRegistry(parseRegistryJson(rawRegistry))
   return cachedRegistry
 }
 
-function readRegistryFile(): unknown {
+function parseRegistryJson(rawRegistry: string): unknown {
   try {
-    return JSON.parse(readFileSync(getRegistryPath(), 'utf-8'))
+    return JSON.parse(rawRegistry)
   } catch {
     return null
   }
 }
 
+/** Read-only callers: an unreadable registry reports no attribution, uncached. */
+function readRegistry(): RegistryFile {
+  return readRegistryOrNull() ?? { version: 2, panes: {} }
+}
+
 function parseRegistry(parsed: unknown): RegistryFile {
   const empty: RegistryFile = { version: 2, panes: {} }
   if (!parsed || typeof parsed !== 'object' || Array.isArray(parsed)) {
@@ -162,7 +188,13 @@ function writeRegistry(registry: RegistryFile): void {
  * Records the account a PTY launched under. Pass null to forget a pinned pane.
  */
 export function recordCodexPaneAccount(ptyId: string, record: CodexPaneAccountRecord | null): void {
-  const registry = readRegistry()
+  // Why: every write below persists the whole registry. Deriving it from an
+  // empty stand-in because the real one could not be read would drop every
+  // other pane's attribution on disk. Skip; the next record retries.
+  const registry = readRegistryOrNull()
+  if (!registry) {
+    return
+  }
   if (!record) {
     if (!(ptyId in registry.panes)) {
       return
@@ -279,7 +311,13 @@ export function hasRecordedManagedHostCodexPane(): boolean {
 
 /** Drops records whose daemon PTYs are authoritatively absent. */
 export function reconcileCodexPaneAccountsWithLivePtys(livePtyIds: readonly string[]): void {
-  const registry = readRegistry()
+  // Why: this deletes every pane not in the live list. Against an empty stand-in
+  // it is a no-op, but the write it guards would still persist that stand-in
+  // over the real file, so refuse rather than reconcile a registry nobody read.
+  const registry = readRegistryOrNull()
+  if (!registry) {
+    return
+  }
   const livePtyIdSet = new Set(livePtyIds)
   let changed = false
   for (const ptyId of Object.keys(registry.panes)) {
diff --git a/src/main/codex/codex-trust-grant-ledger.ts b/src/main/codex/codex-trust-grant-ledger.ts
index b1d20421bce..75a289db22f 100644
--- a/src/main/codex/codex-trust-grant-ledger.ts
+++ b/src/main/codex/codex-trust-grant-ledger.ts
@@ -1,4 +1,5 @@
-import { existsSync, mkdirSync, readFileSync, statSync, writeFileSync } from 'node:fs'
+import { mkdirSync, readFileSync, statSync, writeFileSync } from 'node:fs'
+import { isDefinitiveAbsence } from '../../shared/definitive-filesystem-absence'
 import { dirname, join } from 'node:path'
 import { getOrcaManagedCodexHomePath } from './codex-home-paths'
 import { normalizeCodexProjectPathForLookup } from './config-toml-trust'
@@ -40,13 +41,22 @@ export function getCodexTrustGrantHomeKey(runtimeHomePath: string): string {
   return normalizeCodexProjectPathForLookup(runtimeHomePath)
 }
 
-function readLedgerFile(ledgerPath: string): CodexTrustGrantLedgerFile {
+/**
+ * `null` means the ledger could not be READ, which is different from an absent
+ * or corrupt one. A write derived from `empty` persists a file containing only
+ * the home being written, destroying every other home's grants — so the write
+ * paths refuse on `null` while the read path keeps degrading.
+ */
+function readLedgerFileOrNull(ledgerPath: string): CodexTrustGrantLedgerFile | null {
   const empty: CodexTrustGrantLedgerFile = { version: 1, homes: {} }
-  if (!existsSync(ledgerPath)) {
-    return empty
+  let rawLedger: string
+  try {
+    rawLedger = readFileSync(ledgerPath, 'utf-8')
+  } catch (error) {
+    return isDefinitiveAbsence(error) ? empty : null
   }
   try {
-    const parsed: unknown = JSON.parse(readFileSync(ledgerPath, 'utf-8'))
+    const parsed: unknown = JSON.parse(rawLedger)
     if (
       !parsed ||
       typeof parsed !== 'object' ||
@@ -67,6 +77,11 @@ function readLedgerFile(ledgerPath: string): CodexTrustGrantLedgerFile {
   }
 }
 
+/** Corrupt or absent still degrades to empty — rebuilding those IS the intent. */
+function readLedgerFile(ledgerPath: string): CodexTrustGrantLedgerFile {
+  return readLedgerFileOrNull(ledgerPath) ?? { version: 1, homes: {} }
+}
+
 function persistLedgerFile(ledgerPath: string, file: CodexTrustGrantLedgerFile): void {
   mkdirSync(dirname(ledgerPath), { recursive: true, mode: 0o700 })
   writeFileSync(ledgerPath, `${JSON.stringify(file, null, 2)}\n`, {
@@ -94,7 +109,13 @@ export function writeCodexTrustGrantLedgerHome(
   home: CodexTrustGrantLedgerHome,
   ledgerPath = getCodexTrustGrantLedgerPath()
 ): void {
-  const file = readLedgerFile(ledgerPath)
+  const file = readLedgerFileOrNull(ledgerPath)
+  if (!file) {
+    // Why: writing a file derived from `empty` would drop every other home's
+    // grants, and those homes would then be re-prompted for trust they had
+    // already granted. Skip this write; the next grant retries.
+    return
+  }
   file.homes[getCodexTrustGrantHomeKey(runtimeHomePath)] = home
   persistLedgerFile(ledgerPath, file)
 }
diff --git a/src/main/codex/config-settings-baseline.ts b/src/main/codex/config-settings-baseline.ts
index 6959219c2d2..856352e81f9 100644
--- a/src/main/codex/config-settings-baseline.ts
+++ b/src/main/codex/config-settings-baseline.ts
@@ -1,4 +1,5 @@
 import { existsSync, writeFileSync } from 'node:fs'
+import { isDefinitiveAbsence } from '../../shared/definitive-filesystem-absence'
 import { join } from 'node:path'
 import { readAgentStateFileSync, readAgentStateJsonFileSync } from '../agent-state-file-reader'
 
@@ -20,11 +21,39 @@ type StoredSettingsBaseline = {
   conflicts?: Record<string, CodexSettingsConflict>
 }
 
-export function readCodexSettingsBaseline(runtimeHomePath: string): CodexSettingsBaseline | null {
+/**
+ * Why callers need three answers, not two: the baseline records what Orca last
+ * mirrored, so `null` drives "there is nothing to compare against, bootstrap
+ * one". For a file that merely could not be READ, bootstrapping overwrites the
+ * record of a change the user made inside Codex, and the next mirror pass then
+ * writes the old value back over their edit. Absent and unparseable still map
+ * to `absent` — rebuilding those is the intent.
+ */
+export type CodexSettingsBaselineObservation =
+  | { kind: 'present'; baseline: CodexSettingsBaseline }
+  | { kind: 'absent' }
+  | { kind: 'indeterminate' }
+
+export function observeCodexSettingsBaseline(
+  runtimeHomePath: string
+): CodexSettingsBaselineObservation {
   const baselinePath = getCodexSettingsBaselinePath(runtimeHomePath)
-  if (!existsSync(baselinePath)) {
-    return null
+  const baseline = readParsedCodexSettingsBaseline(baselinePath)
+  if (baseline === 'unreadable') {
+    return { kind: 'indeterminate' }
   }
+  return baseline ? { kind: 'present', baseline } : { kind: 'absent' }
+}
+
+/** Absent and unreadable both collapse to `null`; use the observation to tell them apart. */
+export function readCodexSettingsBaseline(runtimeHomePath: string): CodexSettingsBaseline | null {
+  const observation = observeCodexSettingsBaseline(runtimeHomePath)
+  return observation.kind === 'present' ? observation.baseline : null
+}
+
+function readParsedCodexSettingsBaseline(
+  baselinePath: string
+): CodexSettingsBaseline | null | 'unreadable' {
   try {
     const parsed: unknown = readAgentStateJsonFileSync(baselinePath)
     if (!isStoredSettingsBaseline(parsed)) {
@@ -46,11 +75,18 @@ export function readCodexSettingsBaseline(runtimeHomePath: string): CodexSetting
       }
     }
     return { settings, conflicts }
-  } catch {
-    return null
+  } catch (error) {
+    // Why: a malformed baseline is still `null` — resetting corrupt state is the
+    // intent, and only a read that FAILED must be preserved.
+    return isDefinitiveAbsence(error) || isMalformedBaselineError(error) ? null : 'unreadable'
   }
 }
 
+/** Why: `readAgentStateJsonFileSync` throws for a parse failure and for a size cap alike. */
+function isMalformedBaselineError(error: unknown): boolean {
+  return error instanceof SyntaxError
+}
+
 export function writeCodexSettingsBaseline(
   runtimeHomePath: string,
   baseline: CodexSettingsBaseline
diff --git a/src/main/codex/config-settings-promotion.ts b/src/main/codex/config-settings-promotion.ts
index cd0b703960a..a8a9c2e541b 100644
--- a/src/main/codex/config-settings-promotion.ts
+++ b/src/main/codex/config-settings-promotion.ts
@@ -14,7 +14,7 @@ import {
 import { parseTomlKeyPath, parseTomlTableHeaderPath } from './config-toml-key-path'
 import { tuiStructuredKey, upsertPromotedSettingsInContent } from './codex-config-settings-upsert'
 import {
-  readCodexSettingsBaseline,
+  observeCodexSettingsBaseline,
   writeCodexSettingsBaseline,
   type CodexSettingsBaseline,
   type CodexSettingsConflict
@@ -163,6 +163,13 @@ export function snapshotCodexRuntimeSettingsBaseline(
   runtimeHomePath = getOrcaManagedCodexHomePath(),
   conflicts: ReadonlyMap<string, CodexSettingsConflict> = new Map()
 ): void {
+  // Why: overwriting a baseline that could not be read records whatever the
+  // runtime config says now as "Orca wrote this", so an edit the user made
+  // inside Codex since the last pass is reclassified and never promoted again.
+  // Absent and malformed are still rebuilt — that is what this function is for.
+  if (observeCodexSettingsBaseline(runtimeHomePath).kind === 'indeterminate') {
+    return
+  }
   try {
     const runtimeTomlPath = join(runtimeHomePath, 'config.toml')
     // Why: record an empty baseline even for a missing runtime config, so Codex's first write still diffs and promotes.
@@ -235,10 +242,17 @@ function promoteCodexRuntimeSettingsToSystemUnsafe(
     throw runtimeTomlObservation.error
   }
   // Why: without a baseline, a stale runtime value looks like a fresh in-Codex change; skip until the mirror writes one.
-  const baseline = readCodexSettingsBaseline(runtimeHomePath)
-  if (!baseline) {
+  const baselineObservation = observeCodexSettingsBaseline(runtimeHomePath)
+  if (baselineObservation.kind === 'indeterminate') {
+    // Why: an empty plan here lets the mirror proceed and write the system value
+    // back over an in-Codex edit this baseline would have identified. The caller
+    // turns a throw into the existing stall-and-retry null.
+    throw new Error('Codex settings baseline could not be read')
+  }
+  if (baselineObservation.kind === 'absent') {
     return emptyPromotionPlan()
   }
+  const baseline = baselineObservation.baseline
   const runtimeValues = readPromotedSettingValues(runtimeTomlPath)
   const systemValues = readPromotedSettingValues(systemTomlPath)
   const updates = new Map<string, string>()
diff --git a/src/main/codex/config-sync-stall.ts b/src/main/codex/config-sync-stall.ts
index c03598d4a28..45cf35c78b2 100644
--- a/src/main/codex/config-sync-stall.ts
+++ b/src/main/codex/config-sync-stall.ts
@@ -1,6 +1,5 @@
-import { existsSync } from 'node:fs'
 import { join } from 'node:path'
-import { readAgentStateFileSync } from '../agent-state-file-reader'
+import { observeAgentStateFile, observeResolvedPathEntry } from './codex-path-observation'
 import { getOrcaManagedCodexHomePath, getSystemCodexHomePath } from './codex-home-paths'
 import type { CodexSettingsPromotionHomes } from './config-settings-promotion'
 import type {
@@ -28,20 +27,28 @@ export function getCodexConfigSyncStatus(
   const runtimeConfigPath = join(homes.runtimeHomePath, 'config.toml')
   // Why: a stall only withholds settings once a managed runtime config exists;
   // without one the mirror seeds it and there is nothing yet to fall behind.
-  if (!existsSync(runtimeConfigPath)) {
+  // But `existsSync` said "no runtime config" for one that was merely locked,
+  // and this function then reported `synced` while the mirror was refusing —
+  // telling the user their edits had been applied when nothing had run.
+  const runtimeConfigObservation = observeResolvedPathEntry(runtimeConfigPath)
+  if (runtimeConfigObservation.kind === 'absent') {
     return { state: 'synced', reason: null, systemConfigPath }
   }
-  if (!existsSync(systemConfigPath)) {
+  if (runtimeConfigObservation.kind === 'indeterminate') {
+    // Why: the managed home is what could not be read, so say that rather than
+    // borrowing a source-side reason and blaming the wrong path.
+    return { state: 'stalled', reason: 'managed-home-unavailable', systemConfigPath }
+  }
+  const systemConfigObservation = observeAgentStateFile(systemConfigPath)
+  if (systemConfigObservation.kind === 'absent') {
     return { state: 'stalled', reason: 'missing-source', systemConfigPath }
   }
-  let rawSystemConfig: string
-  try {
-    rawSystemConfig = readAgentStateFileSync(systemConfigPath)
-  } catch {
+  if (systemConfigObservation.kind === 'indeterminate') {
     // Why: the mirror aborts on an unreadable source too, so report the stall
     // rather than claiming a sync that cannot happen.
     return { state: 'stalled', reason: 'unreadable-source', systemConfigPath }
   }
+  const rawSystemConfig = systemConfigObservation.value
   if (rawSystemConfig.trim() === '') {
     return { state: 'stalled', reason: 'blank-source', systemConfigPath }
   }
diff --git a/src/main/codex/config-toml-trust.ts b/src/main/codex/config-toml-trust.ts
index a4768730c5b..18d2c1cfd41 100644
--- a/src/main/codex/config-toml-trust.ts
+++ b/src/main/codex/config-toml-trust.ts
@@ -12,6 +12,7 @@ import {
 import { basename, dirname, join, posix as pathPosix, win32 as pathWin32 } from 'node:path'
 import { createHash, randomUUID } from 'node:crypto'
 import { renameFileWithWindowsRetry } from '../codex-accounts/fs-utils'
+import { observe } from './codex-path-observation'
 import { foldWslUncPathCaseInsensitiveParts } from '../../shared/wsl-paths'
 import { writeRollingFileBackup } from '../rolling-file-backup'
 import {
@@ -337,7 +338,17 @@ export function upsertHookTrustEntries(
   configPath: string,
   entries: readonly CodexTrustEntry[]
 ): void {
-  const existing = existsSync(configPath) ? readTomlFile(configPath) : ''
+  // Why: `existsSync` answered `false` for a locked config exactly as for an
+  // absent one, so `existing` became '' and the upsert below rebuilt the file
+  // from the trust entries alone — replacing the user's model, provider, MCP
+  // servers, approvals and comments with a trust-only stub. Only a definitive
+  // absence may seed from empty; every caller in hook-service already turns a
+  // throw here into "trust entries could not be written. Run /hooks in Codex".
+  const observation = observe(() => readTomlFile(configPath))
+  if (observation.kind === 'indeterminate') {
+    throw observation.error
+  }
+  const existing = observation.kind === 'present' ? observation.value : ''
   const updated = upsertHookTrustEntriesInContent(existing, entries)
   if (updated === existing) {
     return
diff --git a/src/main/codex/sta-4823-shared-state-survives-a-failed-read.test.ts b/src/main/codex/sta-4823-shared-state-survives-a-failed-read.test.ts
new file mode 100644
index 00000000000..eb680ed7d18
--- /dev/null
+++ b/src/main/codex/sta-4823-shared-state-survives-a-failed-read.test.ts
@@ -0,0 +1,412 @@
+import { afterEach, beforeEach, describe, expect, it, vi } from 'vitest'
+import type * as NodeFs from 'node:fs'
+import type * as NodeOs from 'node:os'
+import { tmpdir } from 'node:os'
+import { join } from 'node:path'
+
+// STA-4823: six shared Codex state files were rebuilt, erased or reported as
+// healthy after a read that had merely failed. Every one is reachable on the
+// host lane; the WSL-specific half of the catalogue stays in STA-4606.
+
+const denials = vi.hoisted(() => {
+  const state = {
+    paths: new Set<string>(),
+    readOnlyPaths: new Set<string>(),
+    existenceDeniedPaths: new Set<string>(),
+    deny(path: string): void {
+      state.paths.add(path)
+    },
+    /**
+     * Content reads fail but `existsSync` still says the file is there — the
+     * shape a Windows sharing violation takes, as distinct from `deny`, which
+     * models an ACL denial where `existsSync` itself reports false.
+     */
+    denyReads(path: string): void {
+      state.readOnlyPaths.add(path)
+    },
+    /**
+     * `existsSync` reports false and content reads throw, but `statSync` and the
+     * atomic replace still work. This is the shape that actually loses data: the
+     * caller concludes "no file here", builds fresh content, and the rename
+     * lands because rename needs permission on the DIRECTORY, not the target.
+     * Guarding the write as well would let a test pass because the write failed
+     * rather than because the fix refused.
+     */
+    denyExistence(path: string): void {
+      state.existenceDeniedPaths.add(path)
+    },
+    release(path: string): void {
+      state.paths.delete(path)
+    },
+    reset(): void {
+      state.paths.clear()
+      state.readOnlyPaths.clear()
+      state.existenceDeniedPaths.clear()
+    },
+    check(target: unknown, syscall: string, readOnly = false): void {
+      if (typeof target !== 'string') {
+        return
+      }
+      const readDenied =
+        readOnly && (state.readOnlyPaths.has(target) || state.existenceDeniedPaths.has(target))
+      if (!state.paths.has(target) && !readDenied) {
+        return
+      }
+      const error: NodeJS.ErrnoException = new Error(
+        `EPERM: operation not permitted, ${syscall} '${target}'`
+      )
+      error.code = 'EPERM'
+      error.errno = -4048
+      error.syscall = syscall
+      error.path = target
+      throw error
+    }
+  }
+  return state
+})
+
+// One denial modelled coherently: a denied path throws from every read AND
+// reports false from existsSync. Faulting one but not another lets a test pass
+// against code that still consults the one left healthy.
+vi.mock('node:fs', async (importOriginal) => {
+  const actual = await importOriginal<typeof NodeFs>()
+  const guard = (fn: unknown, syscall: string): unknown => {
+    const original = fn as (...args: unknown[]) => unknown
+    const wrapped = (...args: unknown[]): unknown => {
+      denials.check(args[0], syscall)
+      return original(...args)
+    }
+    return Object.assign(wrapped, original)
+  }
+  const patched: Record<string, unknown> = {
+    ...actual,
+    readFileSync: Object.assign((...args: unknown[]): unknown => {
+      denials.check(args[0], 'read', true)
+      return (actual.readFileSync as (...a: unknown[]) => unknown)(...args)
+    }, actual.readFileSync),
+    // Why: the size-capped agent-state reader opens with `openSync`, so leaving
+    // it unguarded makes a denial invisible to every config/baseline read. Guard
+    // it for READ intent only — a write opens 'w'/'wx'/'a', and the atomic
+    // replace those writes perform must stay healthy (see `deny` above).
+    openSync: Object.assign((...args: unknown[]): unknown => {
+      const flags = args[1]
+      const isRead = flags === undefined || (typeof flags === 'string' && flags.startsWith('r'))
+      if (isRead) {
+        denials.check(args[0], 'open', true)
+      }
+      return (actual.openSync as (...a: unknown[]) => unknown)(...args)
+    }, actual.openSync),
+    statSync: guard(actual.statSync, 'stat'),
+    lstatSync: guard(actual.lstatSync, 'lstat'),
+    existsSync: Object.assign(
+      (...args: unknown[]): boolean =>
+        typeof args[0] === 'string' &&
+        (denials.paths.has(args[0]) || denials.existenceDeniedPaths.has(args[0]))
+          ? false
+          : actual.existsSync(args[0] as string),
+      actual.existsSync
+    )
+  }
+  return { ...patched, default: patched }
+})
+
+const { getPathMock, homedirMock } = vi.hoisted(() => ({
+  getPathMock: vi.fn<(name: string) => string>(),
+  homedirMock: vi.fn<() => string>()
+}))
+
+vi.mock('electron', () => ({ app: { getPath: getPathMock } }))
+
+vi.mock('node:os', async () => {
+  const actual = await vi.importActual<typeof NodeOs>('node:os')
+  return { ...actual, homedir: homedirMock }
+})
+
+const realFs = await vi.importActual<typeof NodeFs>('node:fs')
+
+const { upsertHookTrustEntries, readHookTrustEntries } = await import('./config-toml-trust')
+const {
+  writeCodexTrustGrantLedgerHome,
+  readCodexTrustGrantLedgerHome,
+  getCodexTrustGrantLedgerPath
+} = await import('./codex-trust-grant-ledger')
+const { readHooksJson } = await import('../agent-hooks/hooks-json-read')
+const { snapshotCodexRuntimeSettingsBaseline } = await import('./config-settings-promotion')
+const { getCodexConfigSyncStatus } = await import('./config-sync-stall')
+const paneRegistry = await import('./codex-pane-account-registry')
+
+let fakeHomeDir: string
+let userDataDir: string
+let runtimeHomePath: string
+let previousUserDataPath: string | undefined
+
+const systemHome = (): string => join(fakeHomeDir, '.codex')
+const baselinePath = (): string => join(runtimeHomePath, '.orca-config-settings-baseline.json')
+
+beforeEach(() => {
+  denials.reset()
+  fakeHomeDir = realFs.mkdtempSync(join(tmpdir(), 'orca-sta4823-home-'))
+  userDataDir = realFs.mkdtempSync(join(tmpdir(), 'orca-sta4823-data-'))
+  runtimeHomePath = join(userDataDir, 'codex-runtime-home', 'home')
+  previousUserDataPath = process.env.ORCA_USER_DATA_PATH
+  process.env.ORCA_USER_DATA_PATH = userDataDir
+  homedirMock.mockReturnValue(fakeHomeDir)
+  getPathMock.mockImplementation((name: string) => {
+    if (name === 'userData') {
+      return userDataDir
+    }
+    throw new Error(`unexpected app.getPath(${name})`)
+  })
+  realFs.mkdirSync(runtimeHomePath, { recursive: true })
+  realFs.mkdirSync(systemHome(), { recursive: true })
+  paneRegistry._internals.resetCache()
+})
+
+afterEach(() => {
+  denials.reset()
+  paneRegistry._internals.resetCache()
+  realFs.rmSync(fakeHomeDir, { recursive: true, force: true })
+  realFs.rmSync(userDataDir, { recursive: true, force: true })
+  if (previousUserDataPath === undefined) {
+    delete process.env.ORCA_USER_DATA_PATH
+  } else {
+    process.env.ORCA_USER_DATA_PATH = previousUserDataPath
+  }
+  vi.clearAllMocks()
+})
+
+describe('STA-4823 D29 — an unreadable config.toml must not become a trust-only stub', () => {
+  const USER_CONFIG = [
+    'model = "gpt-5.1-codex-max"',
+    'model_provider = "openai"',
+    '',
+    '# my notes',
+    '[mcp_servers.local]',
+    'command = "run-me"',
+    ''
+  ].join('\n')
+  const ENTRY = [
+    {
+      sourcePath: '/tmp/hooks.json',
+      eventLabel: 'stop',
+      groupIndex: 0,
+      hookIndex: 0,
+      trustedHash: 'sha256:x',
+      enabled: true
+    }
+  ]
+
+  it('refuses the write rather than rebuilding the file from the trust entries alone', () => {
+    const configPath = join(runtimeHomePath, 'config.toml')
+    realFs.writeFileSync(configPath, USER_CONFIG, 'utf-8')
+    denials.denyExistence(configPath)
+
+    // Every hook-service caller already turns this throw into "trust entries
+    // could not be written. Run /hooks in Codex to approve."
+    expect(() => upsertHookTrustEntries(configPath, ENTRY as never)).toThrow('EPERM')
+
+    // Before the fix, existsSync said the file was gone, `existing` became '',
+    // and the upsert wrote a config containing ONLY the trust table — the
+    // user's model, provider, MCP servers and comments all discarded.
+    expect(realFs.readFileSync(configPath, 'utf-8')).toBe(USER_CONFIG)
+  })
+
+  it('still seeds a config.toml that does not exist yet', () => {
+    const configPath = join(runtimeHomePath, 'config.toml')
+
+    // Why: seeding from empty is correct for a genuine absence, and is how a
+    // fresh managed home gets its trust entries at all.
+    upsertHookTrustEntries(configPath, ENTRY as never)
+
+    expect(readHookTrustEntries(configPath).size).toBeGreaterThan(0)
+  })
+})
+
+describe('STA-4823 D30 — an unreadable trust-grant ledger must not be rewritten from empty', () => {
+  const OTHER_HOME = '/some/other/managed/home'
+
+  function seedLedgerWithAnotherHome(): string {
+    const ledgerPath = getCodexTrustGrantLedgerPath()
+    writeCodexTrustGrantLedgerHome(
+      OTHER_HOME,
+      { entries: { 'a:b': { trustedHash: 'sha256:other' } } } as never,
+      ledgerPath
+    )
+    return ledgerPath
+  }
+
+  it('skips the write instead of dropping every other home', () => {
+    const ledgerPath = seedLedgerWithAnotherHome()
+    const before = realFs.readFileSync(ledgerPath, 'utf-8')
+    denials.deny(ledgerPath)
+
+    writeCodexTrustGrantLedgerHome(
+      runtimeHomePath,
+      { entries: { 'c:d': { trustedHash: 'sha256:mine' } } } as never,
+      ledgerPath
+    )
+
+    // Before the fix the read degraded to an empty ledger and the write
+    // persisted a file holding only this home, so every other home lost its
+    // grants and would be re-prompted for trust it had already given.
+    expect(realFs.readFileSync(ledgerPath, 'utf-8')).toBe(before)
+  })
+
+  it('still records a home when the ledger is readable', () => {
+    const ledgerPath = seedLedgerWithAnotherHome()
+
+    // Why: the anchor. Refusing whenever a read fails would stop the ledger
+    // ever recording a grant.
+    writeCodexTrustGrantLedgerHome(
+      runtimeHomePath,
+      { entries: { 'c:d': { trustedHash: 'sha256:mine' } } } as never,
+      ledgerPath
+    )
+
+    expect(readCodexTrustGrantLedgerHome(runtimeHomePath, ledgerPath)).not.toBeNull()
+    expect(readCodexTrustGrantLedgerHome(OTHER_HOME, ledgerPath)).not.toBeNull()
+  })
+})
+
+describe('STA-4823 D33 — an unreadable hooks.json is not an empty hooks.json', () => {
+  it('reports a failed read as unknown rather than as no hooks configured', () => {
+    const hooksPath = join(runtimeHomePath, 'hooks.json')
+    realFs.writeFileSync(hooksPath, JSON.stringify({ hooks: { Stop: [] } }), 'utf-8')
+    denials.deny(hooksPath)
+
+    // The read arm already returned null for a failed read; the existsSync arm
+    // in front of it returned a VALID EMPTY config, and the installer then
+    // wrote generated hooks over the user's file.
+    expect(readHooksJson(hooksPath)).toBeNull()
+  })
+
+  it('still reports a genuinely absent hooks.json as an empty config', () => {
+    // Why: absence really does mean "no hooks configured", and the installer
+    // depends on that to seed one.
+    expect(readHooksJson(join(runtimeHomePath, 'hooks.json'))).toEqual({})
+  })
+})
+
+describe('STA-4823 D26 — an unreadable settings baseline must not be overwritten', () => {
+  function seedBaseline(): string {
+    realFs.writeFileSync(
+      baselinePath(),
+      `${JSON.stringify({ version: 2, settings: { model: 'old-model' } })}\n`,
+      'utf-8'
+    )
+    return realFs.readFileSync(baselinePath(), 'utf-8')
+  }
+
+  it('leaves the record alone so the pending edit can still be promoted', () => {
+    const before = seedBaseline()
+    realFs.writeFileSync(
+      join(runtimeHomePath, 'config.toml'),
+      'model = "edited-in-codex"\n',
+      'utf-8'
+    )
+    denials.deny(baselinePath())
+
+    snapshotCodexRuntimeSettingsBaseline(runtimeHomePath)
+
+    // Before the fix this recorded "edited-in-codex" as Orca's own write, so
+    // the user's in-Codex change was never promoted and the next mirror pass
+    // wrote the old value back over it.
+    expect(realFs.readFileSync(baselinePath(), 'utf-8')).toBe(before)
+  })
+
+  it('still replaces a baseline that is present but malformed', () => {
+    realFs.writeFileSync(baselinePath(), '{ not json', 'utf-8')
+    realFs.writeFileSync(join(runtimeHomePath, 'config.toml'), 'model = "m"\n', 'utf-8')
+
+    // Why: a corrupt baseline carries no information and resetting it IS the
+    // intent. Only the unreadable case may be preserved, or a user is wedged
+    // on a broken file forever.
+    snapshotCodexRuntimeSettingsBaseline(runtimeHomePath)
+
+    // Asserted against the file rather than the new observation API, so this
+    // anchor still means something when the fix is reverted.
+    expect(JSON.parse(realFs.readFileSync(baselinePath(), 'utf-8'))).toMatchObject({ version: 2 })
+  })
+})
+
+describe('STA-4823 D15 — the sync status must not report synced while the mirror refuses', () => {
+  it('reports the managed home as unavailable when its config cannot be read', () => {
+    const runtimeConfigPath = join(runtimeHomePath, 'config.toml')
+    realFs.writeFileSync(runtimeConfigPath, 'model = "m"\n', 'utf-8')
+    realFs.writeFileSync(join(systemHome(), 'config.toml'), 'model = "s"\n', 'utf-8')
+    denials.deny(runtimeConfigPath)
+
+    const status = getCodexConfigSyncStatus({ runtimeHomePath, systemHomePath: systemHome() })
+
+    // Before the fix existsSync reported the locked runtime config as absent
+    // and this returned `synced` — telling the user their edits had been
+    // applied while nothing had run.
+    expect(status).toMatchObject({ state: 'stalled', reason: 'managed-home-unavailable' })
+  })
+
+  it('still reports synced when no runtime config exists yet', () => {
+    realFs.writeFileSync(join(systemHome(), 'config.toml'), 'model = "s"\n', 'utf-8')
+
+    // Why: with no managed config the mirror seeds one; there is nothing to
+    // have fallen behind, and warning here would fire on every fresh install.
+    expect(
+      getCodexConfigSyncStatus({ runtimeHomePath, systemHomePath: systemHome() })
+    ).toMatchObject({ state: 'synced', reason: null })
+  })
+})
+
+describe('STA-4823 D31 — an unreadable pane registry must not erase every attribution', () => {
+  const PANE = 'pty-1'
+  const OTHER_PANE = 'pty-2'
+  const registryPath = (): string => join(userDataDir, 'codex-pane-accounts.json')
+
+  function seedTwoAttributedPanes(): void {
+    paneRegistry.recordCodexPaneAccount(PANE, {
+      selectionKey: 'host',
+      accountId: 'account-1',
+      homeRoute: 'account-home'
+    } as never)
+    paneRegistry.recordCodexPaneAccount(OTHER_PANE, {
+      selectionKey: 'host',
+      accountId: 'account-2',
+      homeRoute: 'account-home'
+    } as never)
+    paneRegistry._internals.resetCache()
+  }
+
+  it('does not persist an empty registry over the real one', () => {
+    seedTwoAttributedPanes()
+    const before = realFs.readFileSync(registryPath(), 'utf-8')
+    denials.deny(registryPath())
+
+    paneRegistry.recordCodexPaneAccount('pty-3', {
+      selectionKey: 'host',
+      accountId: 'account-3',
+      homeRoute: 'account-home'
+    } as never)
+
+    // Before the fix the read degraded to an empty registry and this write
+    // persisted it, dropping every other pane's account attribution on disk.
+    expect(realFs.readFileSync(registryPath(), 'utf-8')).toBe(before)
+  })
+
+  it('does not cache the erasure, so attribution returns when the file does', () => {
+    seedTwoAttributedPanes()
+    denials.deny(registryPath())
+
+    expect(paneRegistry.getCodexPaneAccount(PANE)).toBeNull()
+
+    denials.release(registryPath())
+
+    // THE CACHE is the second half of this defect: one unreadable read used to
+    // pin the empty registry in memory for the rest of the process, so the
+    // attribution never came back even after the file did.
+    expect(paneRegistry.getCodexPaneAccount(PANE)).toMatchObject({ accountId: 'account-1' })
+  })
+
+  it('still reports no attribution when the registry genuinely does not exist', () => {
+    // Why: a fresh install has no registry, and that really is "no panes are
+    // attributed". Refusing here would make every first launch look degraded.
+    expect(paneRegistry.getCodexPaneAccount(PANE)).toBeNull()
+  })
+})