diff --git a/.github/workflows/cd.yaml b/.github/workflows/cd.yaml
index 9a8dba9b..7fc21929 100644
--- a/.github/workflows/cd.yaml
+++ b/.github/workflows/cd.yaml
@@ -56,13 +56,51 @@ jobs:
     runs-on: [self-hosted, harbor, k8s]
     timeout-minutes: 1
     steps:
-      # 2026-03-26: 清理暫存目錄，避免 file conflict (pages + temp)
-      - name: "Clean Runner temp"
+      # =======================================================================
+      # 2026-03-29: Runner _diag/pages 檔案衝突永久修復
+      # 問題: 並行 Job 寫入同一診斷檔案導致 "file already exists"
+      # 解法: 強制清理 + flock 鎖定 + 重建目錄
+      # =======================================================================
+      - name: "Clean Runner Diagnostics (Anti-Collision)"
         run: |
+          set +e  # 不因清理失敗而中斷
+
           RUNNER_ROOT=$(dirname "$(dirname "$RUNNER_TEMP")")
-          rm -rf "$RUNNER_TEMP"/* 2>/dev/null || true
-          rm -rf "$RUNNER_ROOT/_diag/pages"/* 2>/dev/null || true
-          rm -rf .claude/worktrees 2>/dev/null || true
+          DIAG_DIR="$RUNNER_ROOT/_diag"
+          PAGES_DIR="$DIAG_DIR/pages"
+          LOCK_FILE="/tmp/runner-diag-cleanup.lock"
+
+          echo "🧹 Cleaning Runner diagnostics..."
+          echo "   RUNNER_ROOT: $RUNNER_ROOT"
+          echo "   PAGES_DIR: $PAGES_DIR"
+
+          # 使用 flock 確保同一時間只有一個清理程序
+          (
+            flock -w 10 200 || { echo "⚠️ Lock timeout, proceeding anyway"; }
+
+            # 1. 清理 _diag/pages (最關鍵)
+            if [ -d "$PAGES_DIR" ]; then
+              # 刪除所有 .log 檔案
+              find "$PAGES_DIR" -name "*.log" -type f -delete 2>/dev/null
+              # 重建目錄確保乾淨
+              rm -rf "$PAGES_DIR" 2>/dev/null
+              mkdir -p "$PAGES_DIR" 2>/dev/null
+              echo "   ✅ Cleaned _diag/pages"
+            fi
+
+            # 2. 清理 RUNNER_TEMP
+            rm -rf "$RUNNER_TEMP"/* 2>/dev/null
+            echo "   ✅ Cleaned RUNNER_TEMP"
+
+            # 3. 清理 Claude worktrees
+            rm -rf .claude/worktrees 2>/dev/null
+
+            # 4. 清理陳舊的 _work 暫存
+            find "$RUNNER_ROOT/_work" -name "*.tmp" -mmin +30 -delete 2>/dev/null || true
+
+          ) 200>"$LOCK_FILE"
+
+          echo "✅ Runner cleanup completed"
 
       # =======================================================================
       # ADR-035: Telegram 告警鏈路強制驗證
@@ -122,11 +160,12 @@ jobs:
       web: ${{ inputs.force_deploy == true && 'true' || steps.filter.outputs.web }}
       k3s-system: ${{ steps.filter.outputs.k3s-system }}
     steps:
-      # 2026-03-26: 清理暫存目錄 (temp + pages)
-      - name: "Clean Runner temp"
+      # 2026-03-29: Runner 診斷檔案清理 (防止並行衝突)
+      - name: "Clean Runner Diagnostics"
         run: |
           RUNNER_ROOT=$(dirname "$(dirname "$RUNNER_TEMP")")
-          rm -rf "$RUNNER_TEMP"/* "$RUNNER_ROOT/_diag/pages"/* .claude/worktrees 2>/dev/null || true
+          rm -rf "$RUNNER_TEMP"/* "$RUNNER_ROOT/_diag/pages" .claude/worktrees 2>/dev/null || true
+          mkdir -p "$RUNNER_ROOT/_diag/pages" 2>/dev/null || true
 
       - uses: actions/checkout@v4
         with:
@@ -162,11 +201,12 @@ jobs:
     outputs:
       image_tag: ${{ steps.tag.outputs.tag }}
     steps:
-      # 2026-03-26: 清理暫存目錄 (temp + pages)
-      - name: "Clean Runner temp"
+      # 2026-03-29: Runner 診斷檔案清理 (防止並行衝突)
+      - name: "Clean Runner Diagnostics"
         run: |
           RUNNER_ROOT=$(dirname "$(dirname "$RUNNER_TEMP")")
-          rm -rf "$RUNNER_TEMP"/* "$RUNNER_ROOT/_diag/pages"/* .claude/worktrees 2>/dev/null || true
+          rm -rf "$RUNNER_TEMP"/* "$RUNNER_ROOT/_diag/pages" .claude/worktrees 2>/dev/null || true
+          mkdir -p "$RUNNER_ROOT/_diag/pages" 2>/dev/null || true
 
       - uses: actions/checkout@v4
 
@@ -200,11 +240,12 @@ jobs:
     outputs:
       image_tag: ${{ steps.tag.outputs.tag }}
     steps:
-      # 2026-03-26: 清理暫存目錄 (temp + pages)
-      - name: "Clean Runner temp"
+      # 2026-03-29: Runner 診斷檔案清理 (防止並行衝突)
+      - name: "Clean Runner Diagnostics"
         run: |
           RUNNER_ROOT=$(dirname "$(dirname "$RUNNER_TEMP")")
-          rm -rf "$RUNNER_TEMP"/* "$RUNNER_ROOT/_diag/pages"/* .claude/worktrees 2>/dev/null || true
+          rm -rf "$RUNNER_TEMP"/* "$RUNNER_ROOT/_diag/pages" .claude/worktrees 2>/dev/null || true
+          mkdir -p "$RUNNER_ROOT/_diag/pages" 2>/dev/null || true
 
       - uses: actions/checkout@v4
 
@@ -245,11 +286,12 @@ jobs:
     if: always() && (needs.build-api.result == 'success' || needs.build-api.result == 'skipped') && (needs.build-web.result == 'success' || needs.build-web.result == 'skipped')
     environment: production
     steps:
-      # 2026-03-26: 清理暫存目錄 (temp + pages)
-      - name: "Clean Runner temp"
+      # 2026-03-29: Runner 診斷檔案清理 (防止並行衝突)
+      - name: "Clean Runner Diagnostics"
         run: |
           RUNNER_ROOT=$(dirname "$(dirname "$RUNNER_TEMP")")
-          rm -rf "$RUNNER_TEMP"/* "$RUNNER_ROOT/_diag/pages"/* .claude/worktrees 2>/dev/null || true
+          rm -rf "$RUNNER_TEMP"/* "$RUNNER_ROOT/_diag/pages" .claude/worktrees 2>/dev/null || true
+          mkdir -p "$RUNNER_ROOT/_diag/pages" 2>/dev/null || true
 
       - uses: actions/checkout@v4
         with:
diff --git a/ops/runner/README.md b/ops/runner/README.md
new file mode 100644
index 00000000..59f649f0
--- /dev/null
+++ b/ops/runner/README.md
@@ -0,0 +1,66 @@
+# GitHub Actions Runner 穩定性修復
+
+## 問題: `_diag/pages` 檔案衝突
+
+```
+Error: The file '/home/wooo/actions-runner-awoooi/_diag/pages/xxx.log' already exists.
+```
+
+### 根因
+- GitHub Actions Runner 在執行 Job 時會寫入診斷日誌
+- 並行 Job 或快速連續執行可能產生 UUID 碰撞
+- 前次執行的殘留檔案未清理
+
+### 解決方案
+
+#### 1. CD Workflow 修復 (即時生效)
+每個 Job 開始前強制清理並重建 `_diag/pages` 目錄:
+
+```yaml
+- name: "Clean Runner Diagnostics"
+  run: |
+    RUNNER_ROOT=$(dirname "$(dirname "$RUNNER_TEMP")")
+    rm -rf "$RUNNER_TEMP"/* "$RUNNER_ROOT/_diag/pages" .claude/worktrees 2>/dev/null || true
+    mkdir -p "$RUNNER_ROOT/_diag/pages" 2>/dev/null || true
+```
+
+**關鍵**: 刪除整個目錄再重建，而非 `rm -rf _diag/pages/*`
+
+#### 2. Systemd Timer (背景清理)
+每 5 分鐘自動清理過期的診斷檔案:
+
+```bash
+# 部署
+ssh wooo@192.168.0.110
+cd /path/to/awoooi/ops/runner
+bash deploy-runner-cleanup.sh
+```
+
+### 檔案說明
+
+| 檔案 | 用途 |
+|------|------|
+| `cleanup-runner-diag.sh` | 清理腳本 (安裝到 Runner 目錄) |
+| `runner-diag-cleanup.service` | Systemd service 定義 |
+| `runner-diag-cleanup.timer` | Systemd timer (每 5 分鐘) |
+| `deploy-runner-cleanup.sh` | 一鍵部署腳本 |
+
+### 監控
+
+```bash
+# 查看 timer 狀態
+sudo systemctl status runner-diag-cleanup.timer
+
+# 查看清理日誌
+journalctl -u runner-diag-cleanup.service -f
+
+# 手動觸發清理
+sudo systemctl start runner-diag-cleanup.service
+```
+
+### 相關文件
+- Memory: `feedback_runner_zombie_process.md`
+- ADR: 待建立 (如果問題持續)
+
+---
+版本: v1.0 | 建立: 2026-03-29 | 作者: Claude Code
diff --git a/ops/runner/cleanup-runner-diag.sh b/ops/runner/cleanup-runner-diag.sh
new file mode 100644
index 00000000..b4d33f3f
--- /dev/null
+++ b/ops/runner/cleanup-runner-diag.sh
@@ -0,0 +1,82 @@
+#!/bin/bash
+# =============================================================================
+# Runner Diagnostic Cleanup Script
+# =============================================================================
+# 解決 _diag/pages 檔案衝突問題
+#
+# 部署位置: 192.168.0.110 (awoooi-runner)
+# 執行方式: systemd timer 每 5 分鐘執行
+#
+# 版本: v1.0
+# 建立: 2026-03-29 (台北時區)
+# 建立者: Claude Code (Runner 穩定性修復)
+# =============================================================================
+
+set -euo pipefail
+
+RUNNER_DIR="/home/wooo/actions-runner-awoooi"
+DIAG_PAGES_DIR="${RUNNER_DIR}/_diag/pages"
+LOG_FILE="/var/log/runner-diag-cleanup.log"
+MAX_AGE_MINUTES=10
+
+log() {
+    echo "[$(date '+%Y-%m-%d %H:%M:%S')] $1" | tee -a "$LOG_FILE"
+}
+
+# 只有當 Runner 不在執行 Job 時才清理
+check_runner_idle() {
+    # 檢查是否有正在執行的 Job
+    if pgrep -f "Runner.Worker" > /dev/null 2>&1; then
+        return 1  # Runner 忙碌中
+    fi
+    return 0  # Runner 閒置
+}
+
+cleanup_diag_pages() {
+    if [[ ! -d "$DIAG_PAGES_DIR" ]]; then
+        log "DIAG_PAGES_DIR not found, skipping"
+        return 0
+    fi
+
+    # 統計檔案數量
+    local count=$(find "$DIAG_PAGES_DIR" -type f -name "*.log" 2>/dev/null | wc -l)
+
+    if [[ $count -eq 0 ]]; then
+        return 0
+    fi
+
+    log "Found $count diagnostic files"
+
+    # 刪除超過 MAX_AGE_MINUTES 的檔案
+    local deleted=$(find "$DIAG_PAGES_DIR" -type f -name "*.log" -mmin +${MAX_AGE_MINUTES} -delete -print 2>/dev/null | wc -l)
+
+    if [[ $deleted -gt 0 ]]; then
+        log "Deleted $deleted stale files (older than ${MAX_AGE_MINUTES}m)"
+    fi
+}
+
+cleanup_work_temp() {
+    # 清理 _work/_temp 目錄中的殘留檔案
+    local temp_dir="${RUNNER_DIR}/_work/_temp"
+    if [[ -d "$temp_dir" ]]; then
+        local deleted=$(find "$temp_dir" -type f -mmin +30 -delete -print 2>/dev/null | wc -l)
+        if [[ $deleted -gt 0 ]]; then
+            log "Deleted $deleted temp files from _work/_temp"
+        fi
+    fi
+}
+
+main() {
+    # 檢查 Runner 是否閒置
+    if ! check_runner_idle; then
+        log "Runner is busy, skipping cleanup"
+        exit 0
+    fi
+
+    cleanup_diag_pages
+    cleanup_work_temp
+
+    log "Cleanup completed"
+}
+
+main "$@"
diff --git a/ops/runner/deploy-runner-cleanup.sh b/ops/runner/deploy-runner-cleanup.sh
new file mode 100644
index 00000000..fd848363
--- /dev/null
+++ b/ops/runner/deploy-runner-cleanup.sh
@@ -0,0 +1,52 @@
+#!/bin/bash
+# =============================================================================
+# Deploy Runner Diagnostic Cleanup Service
+# =============================================================================
+# 在 192.168.0.110 (Runner 主機) 上執行此腳本
+#
+# 執行方式:
+#   ssh wooo@192.168.0.110
+#   bash /path/to/deploy-runner-cleanup.sh
+#
+# 版本: v1.0
+# 建立: 2026-03-29 (台北時區)
+# =============================================================================
+
+set -euo pipefail
+
+RUNNER_DIR="/home/wooo/actions-runner-awoooi"
+SCRIPT_DIR="$(cd "$(dirname "$0")" && pwd)"
+
+echo "🚀 Deploying Runner Diagnostic Cleanup Service..."
+
+# 1. 複製清理腳本
+echo "📋 Copying cleanup script..."
+cp "$SCRIPT_DIR/cleanup-runner-diag.sh" "$RUNNER_DIR/"
+chmod +x "$RUNNER_DIR/cleanup-runner-diag.sh"
+
+# 2. 安裝 systemd 服務
+echo "📋 Installing systemd service..."
+sudo cp "$SCRIPT_DIR/runner-diag-cleanup.service" /etc/systemd/system/
+sudo cp "$SCRIPT_DIR/runner-diag-cleanup.timer" /etc/systemd/system/
+
+# 3. 重載 systemd
+echo "🔄 Reloading systemd..."
+sudo systemctl daemon-reload
+
+# 4. 啟用並啟動 timer
+echo "⏰ Enabling cleanup timer..."
+sudo systemctl enable --now runner-diag-cleanup.timer
+
+# 5. 驗證
+echo ""
+echo "✅ Deployment complete!"
+echo ""
+echo "📊 Timer status:"
+sudo systemctl status runner-diag-cleanup.timer --no-pager || true
+echo ""
+echo "📊 Next scheduled runs:"
+sudo systemctl list-timers runner-diag-cleanup.timer --no-pager || true
+echo ""
+echo "📝 To test manually:"
+echo "   sudo systemctl start runner-diag-cleanup.service"
+echo "   journalctl -u runner-diag-cleanup.service -f"
diff --git a/ops/runner/runner-diag-cleanup.service b/ops/runner/runner-diag-cleanup.service
new file mode 100644
index 00000000..ef78cc42
--- /dev/null
+++ b/ops/runner/runner-diag-cleanup.service
@@ -0,0 +1,21 @@
+# =============================================================================
+# Runner Diagnostic Cleanup Service
+# =============================================================================
+# 部署: sudo cp runner-diag-cleanup.service /etc/systemd/system/
+# 啟用: sudo systemctl enable --now runner-diag-cleanup.timer
+# =============================================================================
+
+[Unit]
+Description=GitHub Actions Runner Diagnostic Cleanup
+After=network.target
+
+[Service]
+Type=oneshot
+User=wooo
+Group=wooo
+ExecStart=/home/wooo/actions-runner-awoooi/cleanup-runner-diag.sh
+StandardOutput=journal
+StandardError=journal
+
+[Install]
+WantedBy=multi-user.target
diff --git a/ops/runner/runner-diag-cleanup.timer b/ops/runner/runner-diag-cleanup.timer
new file mode 100644
index 00000000..d1169717
--- /dev/null
+++ b/ops/runner/runner-diag-cleanup.timer
@@ -0,0 +1,18 @@
+# =============================================================================
+# Runner Diagnostic Cleanup Timer
+# =============================================================================
+# 每 5 分鐘執行一次清理，防止 _diag/pages 檔案堆積
+# =============================================================================
+
+[Unit]
+Description=Runner Diagnostic Cleanup Timer
+Requires=runner-diag-cleanup.service
+
+[Timer]
+OnBootSec=1min
+OnUnitActiveSec=5min
+AccuracySec=30s
+Persistent=true
+
+[Install]
+WantedBy=timers.target