Dramatically improve temperature proxy installation robustness

Users were abandoning Pulse due to catastrophic temperature monitoring setup failures. This commit addresses the root causes:

**Problem 1: Silent Failures**
- Installations reported "SUCCESS" even when proxy never started
- UI showed green checkmarks with no temperature data
- Zero feedback when things went wrong

**Problem 2: Missing Diagnostics**
- Service failures logged only in journald
- Users saw "Something going on with the proxy" with no actionable guidance
- No way to troubleshoot from error messages

**Problem 3: Standalone Node Issues**
- Proxy daemon logged continuous pvecm errors as warnings
- "ipcc_send_rec" and "Unknown error -1" messages confused users
- These are expected for non-clustered/LXC setups

**Solutions Implemented:**

1. **Health Gate in install.sh (lines 1588-1629)**
   - Verify service is running after installation
   - Check socket exists on host
   - Confirm socket visible inside container via bind mount
   - Fail loudly with specific diagnostics if any check fails

2. **Actionable Error Messages in install-sensor-proxy.sh (lines 822-877)**
   - When service fails to start: dump full systemctl status + 40 lines of logs
   - When socket missing: show permissions, service status, and remediation command
   - Include common issues checklist (missing user, permission errors, lm-sensors, etc.)
   - Direct link to troubleshooting docs

3. **Better Standalone Node Detection in ssh.go (lines 585-595)**
   - Recognize "Unknown error -1" and "Unable to load access control list" as LXC indicators
   - Log at INFO level (not WARN) since this is expected behavior
   - Clarify message: "using localhost for temperature collection"

**Impact:**
- Eliminates "green checkmark but no temps" scenario
- Users get immediate actionable feedback on failures
- Standalone/LXC installations work silently without error spam
- Reduces support burden from #571 (15+ comments of user frustration)

Related to #571

cmd/pulse-sensor-proxy/ssh.go

@@ -582,15 +582,20 @@ func discoverClusterNodes() ([]string, error) {
 		// Check if this is a standalone node or LXC container
 		// - "does not exist" or "not part of a cluster": standalone node
 		// - "ipcc_send_rec": running in LXC container without corosync access
+		// - "Unknown error -1": LXC container corosync communication failure
+		// - "Unable to load access control list": Permission/access issues in containers
 		// Note: Some Proxmox versions write these messages to stdout, others to stderr
 		if strings.Contains(combinedOutput, "does not exist") ||
 			strings.Contains(combinedOutput, "not part of a cluster") ||
-			strings.Contains(combinedOutput, "ipcc_send_rec") {
-			log.Info().Msg("Standalone Proxmox node or LXC container detected - discovering local host addresses")
+			strings.Contains(combinedOutput, "ipcc_send_rec") ||
+			strings.Contains(combinedOutput, "Unknown error -1") ||
+			strings.Contains(combinedOutput, "Unable to load access control list") {
+			// Log at INFO level since this is expected for standalone/container scenarios
+			log.Info().Msg("Standalone Proxmox node or LXC container detected - using localhost for temperature collection")
 			return discoverLocalHostAddresses()
 		}
-		// For other errors, fail
-		log.Warn().Str("stderr", stderrStr).Str("stdout", stdoutStr).Msg("pvecm status failed")
+		// For other unexpected errors, fail with details
+		log.Warn().Str("stderr", stderrStr).Str("stdout", stdoutStr).Msg("pvecm status failed with unexpected error")
 		return nil, fmt.Errorf("failed to get cluster status: %w (stderr: %s, stdout: %s)", err, stderrStr, stdoutStr)
 	}
 

install.sh

@@ -1583,7 +1583,50 @@ fi'; then
             fi
 
             if bash "$proxy_script" "${proxy_install_args[@]}" 2>&1 | tee /tmp/proxy-install-${CTID}.log; then
-                print_info "Temperature proxy installed successfully"
+                print_info "Temperature proxy installation script completed"
+
+                # Verify proxy is actually working
+                echo
+                print_info "Verifying temperature proxy health..."
+                local proxy_health_ok=true
+
+                # Check 1: Service is running
+                if ! systemctl is-active --quiet pulse-sensor-proxy 2>/dev/null; then
+                    print_error "✗ Service not running"
+                    proxy_health_ok=false
+                else
+                    print_info "✓ Service running"
+                fi
+
+                # Check 2: Socket exists
+                if [[ ! -S /run/pulse-sensor-proxy/pulse-sensor-proxy.sock ]]; then
+                    print_error "✗ Socket not found at /run/pulse-sensor-proxy/pulse-sensor-proxy.sock"
+                    proxy_health_ok=false
+                else
+                    print_info "✓ Socket exists"
+                fi
+
+                # Check 3: Socket is accessible from container
+                if ! pct exec $CTID -- test -S /mnt/pulse-proxy/pulse-sensor-proxy.sock 2>/dev/null; then
+                    print_error "✗ Socket not visible inside container at /mnt/pulse-proxy/pulse-sensor-proxy.sock"
+                    print_error "  Bind mount may not be configured correctly"
+                    proxy_health_ok=false
+                else
+                    print_info "✓ Socket accessible from container"
+                fi
+
+                if [[ "$proxy_health_ok" != "true" ]]; then
+                    echo
+                    print_error "Temperature proxy health check failed"
+                    print_error "See diagnostics above and logs: /tmp/proxy-install-${CTID}.log"
+                    print_error ""
+                    print_error "Check: systemctl status pulse-sensor-proxy"
+                    print_error "Check: journalctl -u pulse-sensor-proxy -n 50"
+                    echo
+                    exit 1
+                fi
+
+                print_success "Temperature proxy is healthy and ready"
                 # Clean up temporary binary if it was copied
                 [[ -f "$local_proxy_binary" ]] && rm -f "$local_proxy_binary"
             else

scripts/install-sensor-proxy.sh

@@ -821,8 +821,26 @@ fi
 
 if ! systemctl restart pulse-sensor-proxy.service; then
     print_error "Failed to start pulse-sensor-proxy service"
-    print_error "Check service logs:"
-    journalctl -u pulse-sensor-proxy -n 20 --no-pager
+    print_error ""
+    print_error "═══════════════════════════════════════════════════════"
+    print_error "Service Status:"
+    print_error "═══════════════════════════════════════════════════════"
+    systemctl status pulse-sensor-proxy --no-pager --lines=0 2>&1 || true
+    print_error ""
+    print_error "═══════════════════════════════════════════════════════"
+    print_error "Recent Logs (last 40 lines):"
+    print_error "═══════════════════════════════════════════════════════"
+    journalctl -u pulse-sensor-proxy -n 40 --no-pager 2>&1 || true
+    print_error ""
+    print_error "═══════════════════════════════════════════════════════"
+    print_error "Common Issues:"
+    print_error "═══════════════════════════════════════════════════════"
+    print_error "1. Missing user: Run 'useradd --system --no-create-home --group pulse-sensor-proxy'"
+    print_error "2. Permission errors: Check ownership of /var/lib/pulse-sensor-proxy"
+    print_error "3. lm-sensors not installed: Run 'apt-get install lm-sensors && sensors-detect --auto'"
+    print_error "4. Standalone node detection: If you see 'pvecm' errors, this is expected for non-clustered hosts"
+    print_error ""
+    print_error "For more help: https://github.com/rcourtman/Pulse/blob/main/docs/TROUBLESHOOTING.md"
     exit 1
 fi
 
@@ -836,8 +854,26 @@ for i in {1..10}; do
 done
 
 if [[ ! -S "$SOCKET_PATH" ]]; then
-    print_error "Socket did not appear after 10 seconds"
-    print_info "Check service status: systemctl status pulse-sensor-proxy"
+    print_error "Socket did not appear at $SOCKET_PATH after 10 seconds"
+    print_error ""
+    print_error "═══════════════════════════════════════════════════════"
+    print_error "Diagnostics:"
+    print_error "═══════════════════════════════════════════════════════"
+    print_error "Service Status:"
+    systemctl status pulse-sensor-proxy --no-pager 2>&1 || true
+    print_error ""
+    print_error "Socket Directory Permissions:"
+    ls -la /run/pulse-sensor-proxy/ 2>&1 || echo "Directory does not exist"
+    print_error ""
+    print_error "Recent Logs:"
+    journalctl -u pulse-sensor-proxy -n 20 --no-pager 2>&1 || true
+    print_error ""
+    print_error "Common Causes:"
+    print_error "  • Service failed to start (check logs above)"
+    print_error "  • RuntimeDirectory permissions issue"
+    print_error "  • Systemd socket creation failed"
+    print_error ""
+    print_error "Try: systemctl restart pulse-sensor-proxy && watch -n 0.5 'ls -la /run/pulse-sensor-proxy/'"
     exit 1
 fi