diff --git a/BACKLOG.md b/BACKLOG.md
index 4c5cf8a1..6787aa30 100644
--- a/BACKLOG.md
+++ b/BACKLOG.md
@@ -136,7 +136,8 @@ CC-001/CC-002 were consumed by PR #24 fix bundle inline, with no standalone entr
 | CC-691 | 🔵 active | **[pr-gate 在 reviewers 結束後的收尾階段太久：原生 Windows 回報約 6.5 分鐘，沒有階段標記看不出慢在哪一步（issue #754）]** 第 1 步：收尾各步驟加階段事件（`result_verify` 每次呼叫帶路由標籤與結束碼、`preflight_verify`、`assurance`、`qa_finalize`），下一次真實 gate 就能分段；之後依分段結果去掉重複驗證與重複指紋；計畫見下方 CC-691 一節。 | ops/gate | 2026-10-30 | feedback:2026-10-30 pr:#763 pr:#765 pr:#766 pr:#770 | P1 | hygiene |
 | CC-692 | 🔵 active | **[測試套件太慢：`test-pr-gate.sh` 約 330 個案例每個都跑完整 gate，本機 WSL 每分片 8 到 14 分鐘；判斷類案例應降到函式層，端到端只留接線]** 第 1 步（試點）：`gate_reviewer_protocol_verify` 的 9 個純診斷案例改在新 suite `test-gate-reviewer-protocol.sh` 直接呼叫函式（含正向對照與突變驗證），`test-pr-gate.sh` 保留 2 個接線案例；計畫見下方 CC-692 一節。 | ops/test | 2026-11-02 | feedback:2026-11-02 pr:#764 | P2 | hygiene |
 | CC-693 | 🔵 active | **[`gate run` 的 context 階段在新 worktree 每次耗滿 90 秒上限且不保留進度（issue #780）]** 根因：`pmctl_context_workflow_refresh_bounded` 只用 `timeout 90` 從外面殺掉，`workflow-refresh` 沒傳預算給索引，索引在最後才 COMMIT，被殺就全丟。修法：`workflow-refresh` 新增 `--budget-ms`，wrapper 傳上限的三分之二，索引自己停下並保留進度，下一次接續（重用 #760 的機制）。 | ops/gate | 2026-11-05 | feedback:2026-11-05 pr:#784 | P2 | hygiene |
-| CC-694 | 🔵 active | **[`PM_DISPATCH_STATE_ROOT` 用盘符写法时 `gate run` 先报告 detached 启动成功，监督进程不到 1 秒后才以 exit 2 失败（issue #779）]** `gate run` 在父程序、context 刷新與 operation record 之前檢查狀態根的寫法，拒絕時 exit 2、訊息指名變數（`PM_DISPATCH_STATE_ROOT` 或 `XDG_DATA_HOME`），不印 gate id；`docs/platform-support.md` 補一條。 | ops/gate | 2026-11-05 | feedback:2026-11-05 | P2 | hygiene |
+| CC-694 | 🔵 active | **[`PM_DISPATCH_STATE_ROOT` 用盘符写法时 `gate run` 先报告 detached 启动成功，监督进程不到 1 秒后才以 exit 2 失败（issue #779）]** `gate run` 在父程序、context 刷新與 operation record 之前檢查狀態根的寫法，拒絕時 exit 2、訊息指名變數（`PM_DISPATCH_STATE_ROOT` 或 `XDG_DATA_HOME`），不印 gate id；`docs/platform-support.md` 補一條。 | ops/gate | 2026-11-05 | feedback:2026-11-05 pr:#785 | P2 | hygiene |
+| CC-695 | 🔵 active | **[Windows 的 state root ACL 守衛：拒絕訊息沒有說是哪個主體（issue #778），測試的 `%TEMP%` 繼承 `CodexSandboxUsers` 讓 7 個 telemetry 案例失敗（issue #782）]** 守衛本身是對的，不放寬：訊息指名第一個違規主體與是否繼承，附上 `PM_DISPATCH_STATE_ROOT` 補救與不要隨手改父目錄 ACL 的提醒，`docs/platform-support.md` 補一條；`test-pmctl-context.sh` 用 `th_secure_state_root` 給 tmp_root 一個 owner-only ACL。 | ops/portability | 2026-11-05 | feedback:2026-11-05 | P2 | hygiene |
 
 ---
 
@@ -2591,3 +2592,17 @@ symlink 或改名的 adapter 仍被拒絕。
 **未做**：沒有量 issue 提到的「失敗前已花約 100 秒」（那是 [[CC-693]]）；預設狀態根（`$HOME/.local/share/...`）在 Git Bash 本來就是 POSIX 寫法，沒有動。
 
 **See**: issue #779、[[CC-615]]、[[CC-693]]。
+
+---
+
+## CC-695 — state root ACL 守衛的訊息與測試隔離 🔵 active
+
+**Problem**：issue #778 與 #782。原生 Windows 上，`%TEMP%` 與使用者目錄可能繼承 `CodexSandboxUsers` 的 Modify。守衛（`runtime/lib/state-writer.sh`，issue #592）據此拒絕是對的，但 (a) 訊息只寫 `a non-owner principal`，使用者看不出是誰、是不是繼承來的，也沒有補救指引（#778）；(b) `test-pmctl-context.sh` 的 state root 建在 `%TEMP%` 底下，繼承那個授權，7 個 telemetry 案例被守衛擋下，真正的 telemetry 迴歸會被蓋住（#782）。
+
+**修法**：PowerShell 檢查在 UNSAFE 時多輸出第一個違規主體與 `inherited`／`explicit`（`UNSAFE|<identity>|<inherited|explicit>`，bash 端仍接受單純的 `UNSAFE`），守衛與 `pmctl state status` 的原因帶出該主體；守衛另印一行補救（`PM_DISPATCH_STATE_ROOT` 指到只有自己能寫的目錄，繼承的授權可能屬於別的工具，不要未經確認就改父目錄）。`test-pmctl-context.sh` 呼叫既有的 `th_secure_state_root "$tmp_root"`（`test-pmctl-gate.sh` 已這麼做），不放寬守衛。
+
+**驗證（原生 Windows，`%TEMP%` 含 `CodexSandboxUsers:(M)`）**：真實繼承授權（父目錄 `BUILTIN\Users:(M)`）的拒絕訊息為 `... non-owner principal: BUILTIN\Users, inherited`。#782 的 7 個案例（`context.queried` 2、`reuse-scan` 2、`pack` 3）在 main 上失敗，改後通過；`test-state-store.sh` 的 ACL 案例與四個真實 ACL 案例通過，兩個突變（原因不帶主體、PowerShell 不輸出主體）各讓對應案例失敗。
+
+**未做**：`test-pmctl-context.sh` 其餘既有失敗（兩個 `no-arg ... external git repo` 案例以 exit 99 被隔離守衛拒絕、`marker round-trip`）與 ACL 無關，未動；整個套件超過 900 秒上限沒有完整跑；issue #778 建議 3（把已知 Codex 沙箱組列為可配置的允許名單）需要安全上的決定，沒做；守衛仍只指名第一個違規主體。
+
+**See**: issue #778、#782、[[CC-694]]；docs/platform-support.md 的 Windows 一節。
diff --git a/docs/architecture/script-variable-consumers.tsv b/docs/architecture/script-variable-consumers.tsv
index 9f1eb5a3..31d6e8cf 100644
--- a/docs/architecture/script-variable-consumers.tsv
+++ b/docs/architecture/script-variable-consumers.tsv
@@ -374,6 +374,7 @@ PM_DISPATCH_STATE_ROOT	PM_DISPATCH_STATE_ROOT	runtime/lib/pmctl-context.sh	produ
 PM_DISPATCH_STATE_ROOT	PM_DISPATCH_STATE_ROOT	runtime/lib/pmctl-gate.sh	production
 PM_DISPATCH_STATE_ROOT	PM_DISPATCH_STATE_ROOT	runtime/lib/pmctl-worktree.sh	production
 PM_DISPATCH_STATE_ROOT	PM_DISPATCH_STATE_ROOT	runtime/lib/state-paths.sh	production
+PM_DISPATCH_STATE_ROOT	PM_DISPATCH_STATE_ROOT	runtime/lib/state-writer.sh	production
 PM_DISPATCH_TEST_COMMAND_IDENTITY	PM_DISPATCH_TEST_COMMAND_IDENTITY	runtime/bin/pr-gate.sh	production
 PM_DISPATCH_TEST_FORCE_JQ_LF	PM_DISPATCH_TEST_FORCE_JQ_LF	tests/lib/test-harness.sh	test
 PM_DISPATCH_TEST_FORCE_JQ_LF	PM_DISPATCH_TEST_FORCE_JQ_LF	tests/shell/test-jq-lf.sh	test
diff --git a/docs/platform-support.md b/docs/platform-support.md
index 6fab35e8..aa34c15b 100644
--- a/docs/platform-support.md
+++ b/docs/platform-support.md
@@ -359,6 +359,22 @@ things to know:
   safety check, not a change to it. Do not use `PM_DISPATCH_ALLOW_UNSAFE_STATE_ROOT=1` to get past it; it turns the
   check off instead of fixing the directory. `pmctl` itself is unaffected: its state
   root is under your profile, not `%TEMP%`.
+- **`pmctl gate run` can fail with `state-writer: unsafe state root rejected: ... (ACL grants write to a
+  non-owner principal: <principal>, inherited)` on the default state directory.** The check is correct: the
+  directory under your profile inherited a write grant for another account (for example `CodexSandboxUsers`,
+  which `[windows] sandbox = "elevated"` in `~/.codex/config.toml` creates), so another principal could write
+  your run state. The message names the first such principal and whether the grant is inherited or explicit
+  (issue #778). Do not edit the ACL of the default directory or its parent unless you know nothing else needs
+  that grant: the Codex sandbox may. Give `pmctl` a directory only you can write instead, and point
+  `PM_DISPATCH_STATE_ROOT` at it (write it as a POSIX path, `/c/Users/...`):
+
+  ```bash
+  mkdir -p "$HOME/.pm-gate-state"
+  icacls "$(cygpath -w "$HOME/.pm-gate-state")" /inheritance:r /grant:r "$USERNAME:(OI)(CI)F"
+  export PM_DISPATCH_STATE_ROOT="$HOME/.pm-gate-state"
+  ```
+
+  `PM_DISPATCH_ALLOW_UNSAFE_STATE_ROOT=1` turns the check off; do not use it to get past this.
 - **`PM_DISPATCH_STATE_ROOT` (and `XDG_DATA_HOME`) must be written as a POSIX path, `/c/Users/...`,
   not `C:/Users/...`.** The gate's run directory is derived from the state root and its supervisor
   refuses a drive-letter run directory. `pmctl gate run` checks the state root before it starts anything
diff --git a/runtime/lib/pmctl-state.sh b/runtime/lib/pmctl-state.sh
index 51cd03db..a33e4f73 100644
--- a/runtime/lib/pmctl-state.sh
+++ b/runtime/lib/pmctl-state.sh
@@ -63,7 +63,7 @@ _pmctl_state_root_safety() {
       _sw_windows_store_root_allows_write "$store_root" || _win_acl_rc=$?
       if [[ "$_win_acl_rc" -eq 0 ]]; then
         _PMCTL_STATE_SAFE=0
-        _PMCTL_STATE_SAFE_REASONS+=("ACL grants write to a non-owner principal")
+        _PMCTL_STATE_SAFE_REASONS+=("$(_sw_acl_unsafe_reason)")
       elif [[ "$_win_acl_rc" -eq 2 ]]; then
         _PMCTL_STATE_SAFE=0
         _PMCTL_STATE_SAFE_REASONS+=("cannot verify Windows ACL (PowerShell/cygpath unavailable or Get-Acl failed)")
diff --git a/runtime/lib/state-writer.sh b/runtime/lib/state-writer.sh
index 33508dda..08821d1a 100644
--- a/runtime/lib/state-writer.sh
+++ b/runtime/lib/state-writer.sh
@@ -165,7 +165,10 @@ _sw_windows_store_root_allows_write() {
         }
         if ($allowedSids -contains $sid) { continue }
         if (([int]$ace.FileSystemRights -band $writeMask) -ne 0) {
-          Write-Output "UNSAFE"
+          # Issue #778: name the first offending principal and say whether the grant is inherited, so the
+          # rejection can tell the user what to look at. A caller that only compares with "UNSAFE" still works:
+          # the bash side accepts both forms.
+          Write-Output ("UNSAFE|" + $ace.IdentityReference.Value + "|" + $(if ($ace.IsInherited) { "inherited" } else { "explicit" }))
           exit 0
         }
       }
@@ -175,13 +178,23 @@ _sw_windows_store_root_allows_write() {
     }
   ' 2>/dev/null)" || return 2
   out="${out//[$'\r\n']/}"
+  # The first offending principal as "<identity>|<inherited|explicit>", for the rejection message; empty for a
+  # check that did not name one.
+  _SW_ACL_OFFENDER=""
   case "$out" in
     UNSAFE) return 0 ;;
+    UNSAFE\|*) _SW_ACL_OFFENDER="${out#UNSAFE|}"; return 0 ;;
     SAFE) return 1 ;;
     *) return 2 ;;
   esac
 }
 
+# The rejection reason for an ACL that grants write to another principal, naming the first one when the check did
+# (issue #778). One text for the writer and for `pmctl state status`.
+_sw_acl_unsafe_reason() {
+  printf 'ACL grants write to a non-owner principal%s\n' "${_SW_ACL_OFFENDER:+: ${_SW_ACL_OFFENDER//|/, }}"
+}
+
 _sw_unsafe_store_root() {
   local root="$1"
   local reason="$2"
@@ -240,7 +253,10 @@ _sw_ensure_store_root_safe() {
     local _win_acl_rc=0
     _sw_windows_store_root_allows_write "$store_root" || _win_acl_rc=$?
     if [[ "$_win_acl_rc" -eq 0 ]]; then
-      _sw_unsafe_store_root "$(_sw_canonical_store_root "$store_root")" "ACL grants write to a non-owner principal" || return 1
+      if ! _sw_unsafe_store_root "$(_sw_canonical_store_root "$store_root")" "$(_sw_acl_unsafe_reason)"; then
+        printf '%s\n' "state-writer: to use another location set PM_DISPATCH_STATE_ROOT to a directory only you can write (docs/platform-support.md); an inherited grant may belong to another tool, such as the Codex sandbox, so do not remove it from the parent directory without checking" >&2
+        return 1
+      fi
     elif [[ "$_win_acl_rc" -eq 2 ]]; then
       _sw_unsafe_store_root "$(_sw_canonical_store_root "$store_root")" "cannot verify Windows ACL (PowerShell/cygpath unavailable or Get-Acl failed)" || return 1
     fi
diff --git a/tests/shell/test-pmctl-context.sh b/tests/shell/test-pmctl-context.sh
index 9a5e3790..d852e961 100755
--- a/tests/shell/test-pmctl-context.sh
+++ b/tests/shell/test-pmctl-context.sh
@@ -30,6 +30,11 @@ fi
 # reuse-scan emit — into the throwaway tmp_root, so the suite never pollutes or
 # contends on the developer's real install partition. Cases that need a specific
 # root override this locally.
+#
+# On native Windows the writer's guard refuses a state root whose ACL lets another principal write, and %TEMP%
+# often inherits such a grant (CodexSandboxUsers, issue #782); one owner-only ACL on tmp_root is inherited by
+# every state root below it. The guard is not loosened.
+th_secure_state_root "$tmp_root" || { echo "FAIL: cannot give $tmp_root an owner-only ACL" >&2; exit 1; }
 export PM_DISPATCH_STATE_ROOT="$tmp_root/suite-state"
 
 # The developer's live repo context DB. Every context case must operate on an
diff --git a/tests/shell/test-state-store.sh b/tests/shell/test-state-store.sh
index cde2fe80..02c4e98e 100755
--- a/tests/shell/test-state-store.sh
+++ b/tests/shell/test-state-store.sh
@@ -457,22 +457,31 @@ case_state_store_init_windows_acl_unsafe_rejected() {
   #   3. Assert state_store_init fails loudly before writing VERSION.
   local name="state_store_init: Windows ACL write-grant rejected (POSIX mode bits are inert there)"
   should_run "$name" || return 0
-  local store stubs rc=0 stderr_out
-  store="$tmp_root/root-windows-acl-unsafe"
-  mkdir -p "$store"
+  local store stubs rc stderr_out acl_out
   stubs="$tmp_root/windows-acl-unsafe-stubs"
   mkdir -p "$stubs"
   # shellcheck disable=SC2016 # $1/$2 expand when the generated cygpath stub runs.
-  printf '#!/usr/bin/env bash\n[[ "$1" == "-w" ]] || exit 1\nprintf "%%s\\n" "$2"\n' > "$stubs/cygpath"
-  printf '#!/usr/bin/env bash\nprintf "UNSAFE\\n"\n' > "$stubs/powershell.exe"
-  chmod +x "$stubs/cygpath" "$stubs/powershell.exe"
-  stderr_out="$(PATH="$stubs:$PATH" PM_DISPATCH_PLATFORM=windows \
-    PM_DISPATCH_STATE_ROOT="$store" _SW_ALLOW_GLOBAL_PARTITION=1 state_store_init 2>&1 >/dev/null)" || rc=$?
-  if [[ "$rc" -ne 0 && "$stderr_out" == *"ACL grants write to a non-owner principal"* && ! -e "$store/VERSION" ]]; then
-    pass "$name"
-  else
-    fail "$name" "rc=$rc stderr=${stderr_out:-empty}"
-  fi
+  printf '#!/usr/bin/env bash\n[[ "$1" == "-w" ]] || exit 1\nprintf "%%s\n" "$2"\n' > "$stubs/cygpath"
+  chmod +x "$stubs/cygpath"
+  # Two answers from the PowerShell check: a bare UNSAFE (the form before issue #778) and one that names the
+  # principal and says the grant is inherited. Both are rejected before VERSION is written; the second also shows
+  # who to look at and how to point the store elsewhere.
+  for acl_out in 'UNSAFE' 'UNSAFE|HOST\CodexSandboxUsers|inherited'; do
+    store="$tmp_root/root-windows-acl-unsafe-${#acl_out}"
+    mkdir -p "$store"
+    printf '#!/usr/bin/env bash\ncat <<'"'"'ANSWER'"'"'\n%s\nANSWER\n' "$acl_out" > "$stubs/powershell.exe"
+    chmod +x "$stubs/powershell.exe"
+    rc=0
+    stderr_out="$(PATH="$stubs:$PATH" PM_DISPATCH_PLATFORM=windows \
+      PM_DISPATCH_STATE_ROOT="$store" _SW_ALLOW_GLOBAL_PARTITION=1 state_store_init 2>&1 >/dev/null)" || rc=$?
+    if [[ "$rc" -eq 0 || "$stderr_out" != *"ACL grants write to a non-owner principal"* || -e "$store/VERSION" ]]; then
+      fail "$name" "[$acl_out] rc=$rc stderr=${stderr_out:-empty}"; return 0
+    fi
+    if [[ "$acl_out" == *"|"* ]] && [[ "$stderr_out" != *'principal: HOST\CodexSandboxUsers, inherited'* || "$stderr_out" != *"PM_DISPATCH_STATE_ROOT"* ]]; then
+      fail "$name" "the rejection should name the principal and the remedy: ${stderr_out:-empty}"; return 0
+    fi
+  done
+  pass "$name"
 }
 
 case_state_store_init_windows_acl_safe_accepted() {
@@ -677,11 +686,18 @@ _acl_writemask_case() {
   fi
   rc=0
   _sw_windows_store_root_allows_write "$dir" || rc=$?
-  if [[ "$rc" -eq "$expected_rc" ]]; then
-    pass "$name"
-  else
+  if [[ "$rc" -ne "$expected_rc" ]]; then
     fail "$name" "rc=$rc (expected $expected_rc)"
+    return 0
   fi
+  # Issue #778: an unsafe answer names the principal and says whether the grant is inherited. The grant here is
+  # explicit (the directory was stripped of inherited ACEs above); the name is the localized one, so only its
+  # presence is checked.
+  if [[ "$expected_rc" -eq 0 && "${_SW_ACL_OFFENDER:-}" != ?*"|explicit" ]]; then
+    fail "$name" "the offending principal was not named: [${_SW_ACL_OFFENDER:-}]"
+    return 0
+  fi
+  pass "$name"
 }
 
 case_sw_windows_store_root_allows_write_readonly_is_safe() {