Add stability hardening and self-heal recovery

audit/internal/webui/api.go

@@ -110,6 +110,11 @@ func streamCmdJob(j *jobState, cmd *exec.Cmd) error {
 
 	scanDone := make(chan error, 1)
 	go func() {
+		defer func() {
+			if rec := recover(); rec != nil {
+				scanDone <- fmt.Errorf("stream scanner panic: %v", rec)
+			}
+		}()
 		scanner := bufio.NewScanner(pr)
 		scanner.Buffer(make([]byte, 0, 64*1024), 1024*1024)
 		for scanner.Scan() {

audit/internal/webui/jobs.go

@@ -84,12 +84,12 @@ func (m *jobManager) create(id string) *jobState {
 	j := &jobState{}
 	m.jobs[id] = j
 	// Schedule cleanup after 30 minutes
-	go func() {
+	goRecoverOnce("job cleanup", func() {
 		time.Sleep(30 * time.Minute)
 		m.mu.Lock()
 		delete(m.jobs, id)
 		m.mu.Unlock()
-	}()
+	})
 	return j
 }
 

audit/internal/webui/kmsg_watcher.go

@@ -17,10 +17,10 @@ import (
 // It supports multiple concurrent SAT tasks: a shared event window is open
 // while any SAT task is running, and flushed when all tasks complete.
 type kmsgWatcher struct {
-	mu           sync.Mutex
-	activeCount  int        // number of in-flight SAT tasks
-	window       *kmsgWindow
-	statusDB     *app.ComponentStatusDB
+	mu          sync.Mutex
+	activeCount int // number of in-flight SAT tasks
+	window      *kmsgWindow
+	statusDB    *app.ComponentStatusDB
 }
 
 type kmsgWindow struct {
@@ -48,36 +48,39 @@ func newKmsgWatcher(statusDB *app.ComponentStatusDB) *kmsgWatcher {
 
 // start launches the background kmsg reading goroutine.
 func (w *kmsgWatcher) start() {
-	go w.run()
+	goRecoverLoop("kmsg watcher", 5*time.Second, w.run)
 }
 
 func (w *kmsgWatcher) run() {
-	f, err := os.Open("/dev/kmsg")
-	if err != nil {
-		slog.Warn("kmsg watcher unavailable", "err", err)
-		return
-	}
-	defer f.Close()
-
-	// Best-effort seek to end so we only capture events from now forward.
-	_, _ = f.Seek(0, io.SeekEnd)
-
-	scanner := bufio.NewScanner(f)
-	scanner.Buffer(make([]byte, 64*1024), 64*1024)
-	for scanner.Scan() {
-		line := scanner.Text()
-		evt, ok := parseKmsgLine(line)
-		if !ok {
+	for {
+		f, err := os.Open("/dev/kmsg")
+		if err != nil {
+			slog.Warn("kmsg watcher unavailable", "err", err)
+			time.Sleep(30 * time.Second)
 			continue
 		}
-		w.mu.Lock()
-		if w.window != nil {
-			w.recordEvent(evt)
+		// Best-effort seek to end so we only capture events from now forward.
+		_, _ = f.Seek(0, io.SeekEnd)
+
+		scanner := bufio.NewScanner(f)
+		scanner.Buffer(make([]byte, 64*1024), 64*1024)
+		for scanner.Scan() {
+			line := scanner.Text()
+			evt, ok := parseKmsgLine(line)
+			if !ok {
+				continue
+			}
+			w.mu.Lock()
+			if w.window != nil {
+				w.recordEvent(evt)
+			}
+			w.mu.Unlock()
 		}
-		w.mu.Unlock()
-	}
-	if err := scanner.Err(); err != nil {
-		slog.Warn("kmsg watcher stopped", "err", err)
+		if err := scanner.Err(); err != nil {
+			slog.Warn("kmsg watcher stopped", "err", err)
+		}
+		_ = f.Close()
+		time.Sleep(2 * time.Second)
 	}
 }
 
@@ -134,7 +137,7 @@ func (w *kmsgWatcher) NotifyTaskFinished(taskID string) {
 	if window == nil || len(window.events) == 0 {
 		return
 	}
-	go w.flushWindow(window)
+	goRecoverOnce("kmsg watcher flush", func() { w.flushWindow(window) })
 }
 
 func (w *kmsgWatcher) flushWindow(window *kmsgWindow) {

audit/internal/webui/server.go

@@ -11,6 +11,7 @@ import (
 	"net/http"
 	"os"
 	"path/filepath"
+	"runtime/debug"
 	"sort"
 	"strconv"
 	"strings"
@@ -311,11 +312,11 @@ func NewHandler(opts HandlerOptions) http.Handler {
 	mux.HandleFunc("GET /", h.handlePage)
 
 	h.mux = mux
-	return mux
+	return recoverMiddleware(mux)
 }
 
 func (h *handler) startMetricsCollector() {
-	go func() {
+	goRecoverLoop("metrics collector", 2*time.Second, func() {
 		ticker := time.NewTicker(metricsCollectInterval)
 		defer ticker.Stop()
 		for range ticker.C {
@@ -326,7 +327,7 @@ func (h *handler) startMetricsCollector() {
 			h.feedRings(sample)
 			h.setLatestMetric(sample)
 		}
-	}()
+	})
 }
 
 func (h *handler) setLatestMetric(sample platform.LiveMetricSample) {
@@ -347,7 +348,49 @@ func (h *handler) latestMetric() (platform.LiveMetricSample, bool) {
 
 // ListenAndServe starts the HTTP server.
 func ListenAndServe(addr string, opts HandlerOptions) error {
-	return http.ListenAndServe(addr, NewHandler(opts))
+	srv := &http.Server{
+		Addr:              addr,
+		Handler:           NewHandler(opts),
+		ReadHeaderTimeout: 5 * time.Second,
+		ReadTimeout:       30 * time.Second,
+		IdleTimeout:       2 * time.Minute,
+	}
+	return srv.ListenAndServe()
+}
+
+type trackingResponseWriter struct {
+	http.ResponseWriter
+	wroteHeader bool
+}
+
+func (w *trackingResponseWriter) WriteHeader(statusCode int) {
+	w.wroteHeader = true
+	w.ResponseWriter.WriteHeader(statusCode)
+}
+
+func (w *trackingResponseWriter) Write(p []byte) (int, error) {
+	w.wroteHeader = true
+	return w.ResponseWriter.Write(p)
+}
+
+func recoverMiddleware(next http.Handler) http.Handler {
+	return http.HandlerFunc(func(w http.ResponseWriter, r *http.Request) {
+		tw := &trackingResponseWriter{ResponseWriter: w}
+		defer func() {
+			if rec := recover(); rec != nil {
+				slog.Error("http handler panic",
+					"method", r.Method,
+					"path", r.URL.Path,
+					"panic", fmt.Sprint(rec),
+					"stack", string(debug.Stack()),
+				)
+				if !tw.wroteHeader {
+					http.Error(tw, "internal server error", http.StatusInternalServerError)
+				}
+			}
+		}()
+		next.ServeHTTP(tw, r)
+	})
 }
 
 // ── Infrastructure handlers ──────────────────────────────────────────────────

audit/internal/webui/server_test.go

@@ -34,6 +34,23 @@ func TestChartLegendNumber(t *testing.T) {
 	}
 }
 
+func TestRecoverMiddlewareReturns500OnPanic(t *testing.T) {
+	handler := recoverMiddleware(http.HandlerFunc(func(w http.ResponseWriter, r *http.Request) {
+		panic("boom")
+	}))
+	rec := httptest.NewRecorder()
+	req := httptest.NewRequest(http.MethodGet, "/panic", nil)
+
+	handler.ServeHTTP(rec, req)
+
+	if rec.Code != http.StatusInternalServerError {
+		t.Fatalf("status=%d want %d", rec.Code, http.StatusInternalServerError)
+	}
+	if !strings.Contains(rec.Body.String(), "internal server error") {
+		t.Fatalf("body=%q", rec.Body.String())
+	}
+}
+
 func TestChartDataFromSamplesUsesFullHistory(t *testing.T) {
 	samples := []platform.LiveMetricSample{
 		{

audit/internal/webui/stability.go

@@ -0,0 +1,42 @@
+package webui
+
+import (
+	"fmt"
+	"log/slog"
+	"runtime/debug"
+	"time"
+)
+
+func goRecoverLoop(name string, restartDelay time.Duration, fn func()) {
+	go func() {
+		for {
+			if !runRecoverable(name, fn) {
+				return
+			}
+			if restartDelay > 0 {
+				time.Sleep(restartDelay)
+			}
+		}
+	}()
+}
+
+func goRecoverOnce(name string, fn func()) {
+	go func() {
+		_ = runRecoverable(name, fn)
+	}()
+}
+
+func runRecoverable(name string, fn func()) (panicked bool) {
+	defer func() {
+		if rec := recover(); rec != nil {
+			panicked = true
+			slog.Error("recovered panic",
+				"component", name,
+				"panic", fmt.Sprint(rec),
+				"stack", string(debug.Stack()),
+			)
+		}
+	}()
+	fn()
+	return false
+}

audit/internal/webui/tasks.go

@@ -4,10 +4,12 @@ import (
 	"context"
 	"encoding/json"
 	"fmt"
+	"log/slog"
 	"net/http"
 	"os"
 	"os/exec"
 	"path/filepath"
+	"runtime/debug"
 	"sort"
 	"strings"
 	"sync"
@@ -377,7 +379,7 @@ func (q *taskQueue) startWorker(opts *HandlerOptions) {
 	if !q.started {
 		q.loadLocked()
 		q.started = true
-		go q.worker()
+		goRecoverLoop("task worker", 2*time.Second, q.worker)
 	}
 	hasPending := q.nextPending() != nil
 	q.mu.Unlock()
@@ -392,75 +394,90 @@ func (q *taskQueue) startWorker(opts *HandlerOptions) {
 func (q *taskQueue) worker() {
 	for {
 		<-q.trigger
-		setCPUGovernor("performance")
+		func() {
+			setCPUGovernor("performance")
+			defer setCPUGovernor("powersave")
 
-		// Drain all pending tasks and start them in parallel.
-		q.mu.Lock()
-		var batch []*Task
-		for {
-			t := q.nextPending()
-			if t == nil {
-				break
+			// Drain all pending tasks and start them in parallel.
+			q.mu.Lock()
+			var batch []*Task
+			for {
+				t := q.nextPending()
+				if t == nil {
+					break
+				}
+				now := time.Now()
+				t.Status = TaskRunning
+				t.StartedAt = &now
+				t.DoneAt = nil
+				t.ErrMsg = ""
+				j := newTaskJobState(t.LogPath)
+				t.job = j
+				batch = append(batch, t)
 			}
-			now := time.Now()
-			t.Status = TaskRunning
-			t.StartedAt = &now
-			t.DoneAt = nil
-			t.ErrMsg = ""
-			j := newTaskJobState(t.LogPath)
-			t.job = j
-			batch = append(batch, t)
-		}
-		if len(batch) > 0 {
-			q.persistLocked()
-		}
-		q.mu.Unlock()
+			if len(batch) > 0 {
+				q.persistLocked()
+			}
+			q.mu.Unlock()
 
-		var wg sync.WaitGroup
-		for _, t := range batch {
-			t := t
-			j := t.job
-			taskCtx, taskCancel := context.WithCancel(context.Background())
-			j.cancel = taskCancel
-			wg.Add(1)
-			go func() {
-				defer wg.Done()
+			var wg sync.WaitGroup
+			for _, t := range batch {
+				t := t
+				j := t.job
+				taskCtx, taskCancel := context.WithCancel(context.Background())
+				j.cancel = taskCancel
+				wg.Add(1)
+				goRecoverOnce("task "+t.Target, func() {
+					defer wg.Done()
+					defer func() {
+						if rec := recover(); rec != nil {
+							msg := fmt.Sprintf("task panic: %v", rec)
+							slog.Error("task panic",
+								"task_id", t.ID,
+								"target", t.Target,
+								"panic", fmt.Sprint(rec),
+								"stack", string(debug.Stack()),
+							)
+							j.append("ERROR: " + msg)
+							j.finish(msg)
+						}
+					}()
 
-				if q.kmsgWatcher != nil && isSATTarget(t.Target) {
-					q.kmsgWatcher.NotifyTaskStarted(t.ID, t.Target)
-				}
-
-				q.runTask(t, j, taskCtx)
-
-				if q.kmsgWatcher != nil {
-					q.kmsgWatcher.NotifyTaskFinished(t.ID)
-				}
-
-				q.mu.Lock()
-				now2 := time.Now()
-				t.DoneAt = &now2
-				if t.Status == TaskRunning {
-					if j.err != "" {
-						t.Status = TaskFailed
-						t.ErrMsg = j.err
-					} else {
-						t.Status = TaskDone
+					if q.kmsgWatcher != nil && isSATTarget(t.Target) {
+						q.kmsgWatcher.NotifyTaskStarted(t.ID, t.Target)
 					}
-				}
+
+					q.runTask(t, j, taskCtx)
+
+					if q.kmsgWatcher != nil {
+						q.kmsgWatcher.NotifyTaskFinished(t.ID)
+					}
+
+					q.mu.Lock()
+					now2 := time.Now()
+					t.DoneAt = &now2
+					if t.Status == TaskRunning {
+						if j.err != "" {
+							t.Status = TaskFailed
+							t.ErrMsg = j.err
+						} else {
+							t.Status = TaskDone
+						}
+					}
+					q.persistLocked()
+					q.mu.Unlock()
+				})
+			}
+			wg.Wait()
+
+			if len(batch) > 0 {
+				q.mu.Lock()
+				q.prune()
 				q.persistLocked()
 				q.mu.Unlock()
-			}()
-		}
-		wg.Wait()
+			}
+		}()
 
-		if len(batch) > 0 {
-			q.mu.Lock()
-			q.prune()
-			q.persistLocked()
-			q.mu.Unlock()
-		}
-
-		setCPUGovernor("powersave")
 	}
 }