diff --git a/.claude-plugin/marketplace.json b/.claude-plugin/marketplace.json
index 09e2e4b..744e15e 100644
--- a/.claude-plugin/marketplace.json
+++ b/.claude-plugin/marketplace.json
@@ -18,7 +18,7 @@
     {
       "name": "claude-status-hub",
       "description": "Monitor what matters - PRs, music, custom alerts - right in your Claude Code statusline",
-      "version": "1.5.1",
+      "version": "1.5.2",
       "author": {
         "name": "Pavel Fadeev",
         "email": "pavel.fadeev@gmail.com"
diff --git a/plugins/claude-status-hub/.claude-plugin/plugin.json b/plugins/claude-status-hub/.claude-plugin/plugin.json
index eca4a2d..b2c67c9 100644
--- a/plugins/claude-status-hub/.claude-plugin/plugin.json
+++ b/plugins/claude-status-hub/.claude-plugin/plugin.json
@@ -1,6 +1,6 @@
 {
   "name": "claude-status-hub",
-  "version": "1.5.1",
+  "version": "1.5.2",
   "description": "Monitor and act - PRs, calendar, music, custom alerts with contextual actions via /hub-ack",
   "author": {
     "name": "Pavel Fadeev",
diff --git a/plugins/claude-status-hub/bin/refresh-daemon.sh b/plugins/claude-status-hub/bin/refresh-daemon.sh
index 4ccd8a8..c580ae9 100755
--- a/plugins/claude-status-hub/bin/refresh-daemon.sh
+++ b/plugins/claude-status-hub/bin/refresh-daemon.sh
@@ -126,6 +126,20 @@ while true; do
     exit 0
   fi
 
+  # Self-check: exit if another daemon took over the lockfile
+  # This handles the startup race condition: multiple sessions starting simultaneously
+  # all pass the initial lockfile check before any writes its PID. After one sleep cycle,
+  # only the last writer survives because all others see a mismatched lockfile.
+  # See docs/data-safety-guidelines.md for race condition prevention patterns.
+  if [ -f "$LOCKFILE" ]; then
+    CURRENT_LOCK=$(cat "$LOCKFILE" 2>/dev/null)
+    if [ "$CURRENT_LOCK" != "${PLUGIN_VERSION}:$$" ]; then
+      exit 0  # Another daemon owns the lock, gracefully exit
+    fi
+  else
+    exit 0  # Lockfile gone, exit
+  fi
+
   [ -f "$CONFIG" ] || continue
 
   # Check if bridge needs refresh
diff --git a/plugins/claude-status-hub/bin/refresh-prs.sh b/plugins/claude-status-hub/bin/refresh-prs.sh
index 53761ca..1ce8d19 100755
--- a/plugins/claude-status-hub/bin/refresh-prs.sh
+++ b/plugins/claude-status-hub/bin/refresh-prs.sh
@@ -116,7 +116,14 @@ build_foreground() {
   done < <(jq -c '.foreground[] | select(.owner)' "$CONFIG" 2>/dev/null)
 
   [ -n "$updates" ] && jq "$updates" "$CONFIG" > "${CONFIG}.tmp" && mv "${CONFIG}.tmp" "$CONFIG"
-  echo "${result}]"
+
+  # Preserve non-PR foreground items (Slack, Calendar, etc.) - see docs/data-safety-guidelines.md
+  NON_PR_ITEMS=$(jq -c '[.foreground[] | select(.owner | not)]' "$CONFIG" 2>/dev/null || echo '[]')
+  if [ "$NON_PR_ITEMS" != "[]" ] && [ "$NON_PR_ITEMS" != "null" ]; then
+    echo "${result}]" | jq --argjson nonpr "$NON_PR_ITEMS" '. + $nonpr'
+  else
+    echo "${result}]"
+  fi
 }
 
 FOREGROUND=$(build_foreground)
diff --git a/plugins/claude-status-hub/commands/hub.md b/plugins/claude-status-hub/commands/hub.md
index 4826aaa..f352295 100644
--- a/plugins/claude-status-hub/commands/hub.md
+++ b/plugins/claude-status-hub/commands/hub.md
@@ -62,7 +62,11 @@ gh pr view <number> --repo <owner>/<repo> --json state,isDraft,reviewDecision,st
    - D = Draft
    - ✓ = Approved + all checks pass
 4. Read `~/.claude/status-config.json` for lastSeen state
-5. Update config with new PR(s) in `foreground` array
+5. Update config with new PR(s) in `foreground` array:
+   - Check if PR already exists (match by owner/repo/number)
+   - If exists: update in place using jq `|=` operator
+   - If new: append to existing array with `+= [$new_item]`
+   - **NEVER replace the entire foreground array - always merge** (see `docs/data-safety-guidelines.md`)
 6. Write bridge file `/tmp/status-hub.json` - set timestamp at root, preserve `background`, update `foreground` array:
 
    **CRITICAL:** Generate current timestamp in milliseconds: `$(($(date +%s) * 1000))`
diff --git a/plugins/claude-status-hub/docs/data-safety-guidelines.md b/plugins/claude-status-hub/docs/data-safety-guidelines.md
new file mode 100644
index 0000000..ba242d1
--- /dev/null
+++ b/plugins/claude-status-hub/docs/data-safety-guidelines.md
@@ -0,0 +1,102 @@
+# Data Safety Guidelines
+
+This document establishes patterns for safely updating the status hub's data files without data loss.
+
+## Core Principle
+
+**Never overwrite, always merge.** When updating a subset of data (e.g., just PRs or just calendar), preserve items from other services.
+
+## Bridge File Updates (`/tmp/status-hub.json`)
+
+The bridge file has three main sections:
+- `timestamp`: Always update on write
+- `background`: Music/service status
+- `foreground`: Array of tracked items (PRs, calendar, Slack, etc.)
+
+### Correct Pattern: Merge Foreground Items
+
+When refreshing one service, preserve items from other services:
+
+```bash
+# Get existing non-PR items before rebuilding PR list
+NON_PR_ITEMS=$(jq -c '[.foreground[] | select(.owner | not)]' "$CONFIG" 2>/dev/null || echo '[]')
+
+# After building PR array, merge with non-PR items
+echo "$pr_array" | jq --argjson nonpr "$NON_PR_ITEMS" '. + $nonpr'
+```
+
+### Wrong Pattern: Full Replacement
+
+```bash
+# BAD: This loses Slack, calendar, and other items!
+jq '.foreground = $prs' --argjson prs "$PR_ONLY_ARRAY" "$BRIDGE"
+```
+
+## Config File Updates (`~/.claude/status-config.json`)
+
+### Correct Pattern: Targeted Updates with `|=`
+
+```bash
+# Update specific item by matching criteria
+jq '(.foreground[] | select(.number == 123)) |= . + {lastSeen: {...}}' "$CONFIG"
+
+# Update background without touching foreground
+jq '.background |= {service: "spotify", tabId: 123}' "$CONFIG"
+```
+
+### Wrong Pattern: Full Object Replacement
+
+```bash
+# BAD: Replaces entire config, losing other sections!
+echo '{"foreground": [...]}' > "$CONFIG"
+```
+
+## Adding New Items
+
+When adding a new tracked item:
+
+1. Read existing foreground array
+2. Check if item already exists (match by unique key like `owner/repo/number`)
+3. If exists: update in place with `|=`
+4. If new: append with `+= [$new_item]`
+
+```bash
+# Check if PR exists, then add or update
+if jq -e ".foreground[] | select(.owner == \"$owner\" and .repo == \"$repo\" and .number == $number)" "$CONFIG" >/dev/null 2>&1; then
+  # Update existing
+  jq "(.foreground[] | select(.number == $number)) |= . + {lastSeen: {...}}" "$CONFIG"
+else
+  # Append new
+  jq ".foreground += [{owner: \"$owner\", repo: \"$repo\", number: $number}]" "$CONFIG"
+fi
+```
+
+## Checklist for Skill Authors
+
+Before submitting a skill that modifies hub data:
+
+- [ ] Does it preserve items from other services when updating foreground?
+- [ ] Does it use `|=` for targeted updates instead of full replacement?
+- [ ] Does it check for existing items before adding new ones?
+- [ ] Does it preserve background when only updating foreground (and vice versa)?
+- [ ] Does it handle missing files gracefully (create with sensible defaults)?
+
+## Race Condition Prevention
+
+When multiple processes might update the same file:
+
+1. Use atomic writes: write to `.tmp` file first, then `mv` to final location
+2. For daemons: use lockfile with ownership verification (version:PID)
+3. Check file staleness before modifying
+
+```bash
+# Atomic write pattern
+jq '...' "$CONFIG" > "${CONFIG}.tmp" && mv "${CONFIG}.tmp" "$CONFIG"
+```
+
+## Related Files
+
+- `bin/refresh-prs.sh` - PR-only refresh (preserves non-PR items)
+- `bin/update-bridge.sh` - Bridge writer (preserves background/foreground appropriately)
+- `bin/refresh-daemon.sh` - Background daemon with lockfile management
+- `skills/hub-refresh.md` - Full refresh skill
diff --git a/plugins/claude-status-hub/skills/hub-refresh.md b/plugins/claude-status-hub/skills/hub-refresh.md
index 7615f80..736e3be 100644
--- a/plugins/claude-status-hub/skills/hub-refresh.md
+++ b/plugins/claude-status-hub/skills/hub-refresh.md
@@ -21,6 +21,15 @@ function sanitize(str, maxLen = 30) {
 ```
 Limits: title 30 chars, detail 25 chars, artist 20 chars.
 
+## Data Preservation
+
+**See `docs/data-safety-guidelines.md` for merge patterns.**
+
+Key rules:
+- Never overwrite entire foreground array
+- When refreshing one service, preserve items from other services
+- Use `jq` merge operators (`+`, `|=`) not full replacement
+
 ## Step 1: Read Config
 
 ```bash
diff --git a/plugins/claude-status-hub/tests/test-daemon-version.sh b/plugins/claude-status-hub/tests/test-daemon-version.sh
index 1d3f06f..18ac840 100755
--- a/plugins/claude-status-hub/tests/test-daemon-version.sh
+++ b/plugins/claude-status-hub/tests/test-daemon-version.sh
@@ -210,6 +210,27 @@ fi
 # Cleanup daemon
 kill "$DAEMON_PID" 2>/dev/null || true
 
+# --- Test 9: Self-eviction when lockfile ownership changes ---
+# This tests the race condition fix: if another daemon takes over the lockfile,
+# the current daemon should exit gracefully (see docs/data-safety-guidelines.md)
+echo ""
+echo "Test: Daemon self-evicts when lockfile ownership changes"
+rm -f "$LOCKFILE"
+CURRENT_V=$(jq -r '.version' "$PLUGIN_JSON")
+
+# Simulate the lockfile ownership check logic from refresh-daemon.sh
+# A daemon with PID 12345 wrote the lockfile
+echo "${CURRENT_V}:12345" > "$LOCKFILE"
+
+# Another daemon (PID 99999) checks if it owns the lockfile
+CURRENT_LOCK=$(cat "$LOCKFILE" 2>/dev/null)
+MY_EXPECTED="${CURRENT_V}:99999"
+if [ "$CURRENT_LOCK" != "$MY_EXPECTED" ]; then
+  pass "Lockfile ownership mismatch detected (self-eviction trigger)"
+else
+  fail "Lockfile ownership check" "mismatch detected" "false match"
+fi
+
 echo ""
 echo "=== Results ==="
 echo "Passed: $TESTS_PASSED"
diff --git a/plugins/claude-status-hub/tests/test-refresh-prs.sh b/plugins/claude-status-hub/tests/test-refresh-prs.sh
index eea9452..33b6fb1 100755
--- a/plugins/claude-status-hub/tests/test-refresh-prs.sh
+++ b/plugins/claude-status-hub/tests/test-refresh-prs.sh
@@ -505,6 +505,45 @@ else
   fail "Bridge structure" "spotify bg + 1 fg" "$bg_site + $fg_count fg"
 fi
 
+# Test non-PR foreground items are preserved (see docs/data-safety-guidelines.md)
+TESTS_RUN=$((TESTS_RUN + 1))
+# Setup config with both PR and non-PR items
+cat > "$CONFIG" << EOF
+{
+  "foreground": [
+    {
+      "owner": "test",
+      "repo": "repo",
+      "number": 1,
+      "lastSeen": {}
+    },
+    {
+      "service": "slack",
+      "icon": "S",
+      "title": "3 unread",
+      "detail": "#general"
+    },
+    {
+      "service": "calendar",
+      "icon": "📅",
+      "title": "Meeting",
+      "detail": "in 10m"
+    }
+  ]
+}
+EOF
+create_mock_gh "OPEN" "false" "APPROVED" "MERGEABLE" 0 0 0
+run_refresh
+fg_count=$(jq -r '.foreground | length' "$BRIDGE")
+slack_exists=$(jq -r '.foreground[] | select(.service == "slack") | .title' "$BRIDGE")
+calendar_exists=$(jq -r '.foreground[] | select(.service == "calendar") | .title' "$BRIDGE")
+pr_exists=$(jq -r '.foreground[] | select(.site == "github-pr") | .title' "$BRIDGE")
+if [ "$fg_count" = "3" ] && [ "$slack_exists" = "3 unread" ] && [ "$calendar_exists" = "Meeting" ] && [ -n "$pr_exists" ]; then
+  pass "Non-PR foreground items preserved (Slack, Calendar)"
+else
+  fail "Non-PR preservation" "3 items (PR + Slack + Calendar)" "$fg_count items, slack='$slack_exists', calendar='$calendar_exists'"
+fi
+
 echo ""
 echo "Testing auto-merge functionality..."