feat(audit): readable host-scoped Audit log tab + audit message/resource filters (Phase 2b)

api/openapi.yaml

@@ -1101,6 +1101,14 @@ paths:
         - name: actor_type
           in: query
           schema: {type: string}
+        - name: resource_type
+          in: query
+          description: Filter to events whose resource_type matches (e.g. "host"). Pair with resource_id for a single resource's audit trail.
+          schema: {type: string}
+        - name: resource_id
+          in: query
+          description: Filter to events whose resource_id matches (e.g. a host UUID). Typically paired with resource_type.
+          schema: {type: string}
         - name: since
           in: query
           schema: {type: string, format: date-time}
@@ -4673,9 +4681,15 @@ components:
         id: {type: string, format: uuid}
         correlation_id: {type: string}
         action: {type: string}
+        # Server-rendered human-readable sentence for the event
+        # ("<actor> <predicate>", e.g. "alice@example.com created a host"),
+        # built from action + actor_label + actor_type. Lets every audit
+        # surface show a sentence instead of the raw dotted action code.
+        message: {type: string}
         severity: {type: string}
         actor_type: {type: string}
         actor_id: {type: string, nullable: true}
+        actor_label: {type: string, nullable: true}
         resource_type: {type: string, nullable: true}
         resource_id: {type: string, nullable: true}
         occurred_at: {type: string, format: date-time}

frontend/src/api/schema.d.ts

@@ -3102,9 +3102,11 @@ export interface components {
             id: string;
             correlation_id: string;
             action: string;
+            message?: string;
             severity?: string;
             actor_type: string;
             actor_id?: string | null;
+            actor_label?: string | null;
             resource_type?: string | null;
             resource_id?: string | null;
             /** Format: date-time */
@@ -5621,6 +5623,10 @@ export interface operations {
                 action?: string;
                 correlation_id?: string;
                 actor_type?: string;
+                /** @description Filter to events whose resource_type matches (e.g. "host"). Pair with resource_id for a single resource's audit trail. */
+                resource_type?: string;
+                /** @description Filter to events whose resource_id matches (e.g. a host UUID). Typically paired with resource_type. */
+                resource_id?: string;
                 since?: string;
                 until?: string;
                 cursor?: string;

frontend/src/pages/HostDetailPage.tsx

@@ -182,15 +182,13 @@ const TAB_ORDER: { id: TabId; label: string; icon: LucideIcon }[] = [
 // Backend subsystem that populates each tab when it lands. Surfaces
 // inside the per-tab empty state so operators know what's deferred.
 const TAB_BACKEND_SUBSYSTEM: Record<
-  Exclude<TabId, 'overview' | 'compliance' | 'remediation' | 'activity'>,
+  Exclude<TabId, 'overview' | 'compliance' | 'remediation' | 'activity' | 'audit_log'>,
   string
 > = {
   packages: 'Server Intelligence collection — installed-package inventory deferred (BACKLOG).',
   services: 'Server Intelligence collection — running services inventory deferred (BACKLOG).',
   users: 'Server Intelligence collection — user accounts inventory deferred (BACKLOG).',
   network: 'Server Intelligence collection — interfaces and firewall rules deferred (BACKLOG).',
-  audit_log:
-    'Audit query API — host-scoped audit feed deferred to the unified /activity page (BACKLOG).',
   terminal: 'Web terminal — SSH-in-browser deferred; use a host-side SSH client in the meantime.',
 };
 
@@ -488,6 +486,8 @@ export function HostDetailPage() {
             <RemediationTab hostId={detailQuery.data.host.id} />
           ) : activeTab === 'activity' ? (
             <HostActivityTab hostId={detailQuery.data.host.id} />
+          ) : activeTab === 'audit_log' ? (
+            <HostAuditLogTab hostId={detailQuery.data.host.id} />
           ) : (
             <TabStub tab={activeTab} subsystem={TAB_BACKEND_SUBSYSTEM[activeTab]} />
           )}
@@ -2675,6 +2675,137 @@ function HostActivityTab({ hostId }: { hostId: string }) {
   );
 }
 
+// AuditLogItem mirrors the api.AuditEvent envelope returned by
+// GET /api/v1/audit/events. `message` is the server-rendered readable
+// sentence ("<actor> <predicate>"); we never show the raw action code.
+interface AuditLogItem {
+  id: string;
+  action: string;
+  message?: string;
+  actor_label?: string | null;
+  occurred_at: string;
+}
+
+// HostAuditLogTab is the host-scoped forensic audit trail: audit events
+// whose resource is this host (resource_type=host, resource_id=hostId),
+// rendered with the server's readable message. Distinct from the Activity
+// tab (operational feed) — this is the "who did what to this host" record.
+// Gated on audit:read. Spec frontend-host-detail.
+function HostAuditLogTab({ hostId }: { hostId: string }) {
+  const canRead = useAuthStore((s) => s.hasPermission('audit:read'));
+  const q = useInfiniteQuery({
+    queryKey: ['host', hostId, 'audit'],
+    initialPageParam: undefined as string | undefined,
+    enabled: !!hostId && canRead,
+    queryFn: async ({ pageParam }) => {
+      const { data, error, response } = await api.GET('/api/v1/audit/events', {
+        params: {
+          query: {
+            resource_type: 'host',
+            resource_id: hostId,
+            limit: 50,
+            ...(pageParam ? { cursor: pageParam } : {}),
+          },
+        },
+      });
+      if (error || !response.ok) {
+        throw new Error(apiErrorMessage(error, `Failed to load audit log (${response.status})`));
+      }
+      return data as unknown as { items: AuditLogItem[]; next_cursor?: string | null };
+    },
+    getNextPageParam: (last) => last.next_cursor ?? undefined,
+  });
+
+  if (!canRead) {
+    return (
+      <Card title="Audit log">
+        <EmptyState
+          primary="Audit log not available"
+          secondary="Viewing the audit trail requires the audit:read permission."
+        />
+      </Card>
+    );
+  }
+
+  const items = q.data?.pages.flatMap((p) => p.items ?? []) ?? [];
+
+  return (
+    <Card title="Audit log">
+      {q.isLoading ? (
+        <div style={{ color: 'var(--ow-fg-2)', fontSize: 12 }}>Loading…</div>
+      ) : q.isError ? (
+        <div
+          style={{
+            color: 'var(--ow-crit)',
+            fontSize: 12,
+            display: 'flex',
+            gap: 8,
+            alignItems: 'center',
+          }}
+        >
+          {apiErrorMessage(q.error, 'Failed to load audit log')}{' '}
+          <button type="button" onClick={() => q.refetch()} style={smallTextBtn}>
+            <RefreshCw size={11} /> Retry
+          </button>
+        </div>
+      ) : items.length === 0 ? (
+        <EmptyState
+          primary="No audit events yet"
+          secondary="Records who did what to this host (created, updated, scanned, remediated). Entries appear as operators act on the host."
+        />
+      ) : (
+        <>
+          <ol
+            style={{
+              listStyle: 'none',
+              padding: 0,
+              margin: 0,
+              display: 'flex',
+              flexDirection: 'column',
+              gap: 8,
+            }}
+          >
+            {items.map((it) => (
+              <li
+                key={it.id}
+                style={{
+                  display: 'flex',
+                  gap: 10,
+                  alignItems: 'flex-start',
+                  padding: '8px 0',
+                  borderBottom: '1px solid var(--ow-line)',
+                }}
+              >
+                <FileText
+                  size={14}
+                  color="var(--ow-fg-2)"
+                  style={{ marginTop: 2, flexShrink: 0 }}
+                />
+                <div style={{ flex: 1, minWidth: 0, color: 'var(--ow-fg-0)', fontSize: 13 }}>
+                  {it.message || it.action}
+                </div>
+                <div style={{ color: 'var(--ow-fg-3)', fontSize: 11, whiteSpace: 'nowrap' }}>
+                  {relativeTime(it.occurred_at)}
+                </div>
+              </li>
+            ))}
+          </ol>
+          {q.hasNextPage ? (
+            <button
+              type="button"
+              onClick={() => q.fetchNextPage()}
+              disabled={q.isFetchingNextPage}
+              style={{ ...smallTextBtn, marginTop: 12 }}
+            >
+              {q.isFetchingNextPage ? 'Loading…' : 'Load more'}
+            </button>
+          ) : null}
+        </>
+      )}
+    </Card>
+  );
+}
+
 // activitySeverityColors maps the closed severity enum onto the
 // existing OW color tokens.
 function activitySeverityColors(s: ActivitySeverity): { fg: string; dot: string } {

frontend/tests/pages/host-detail-compliance-tab.test.tsx

@@ -156,9 +156,9 @@ describe('frontend-host-compliance-tab — structural', () => {
     expect(PAGE_SRC).toContain('<ComplianceTab');
     // The stub registry no longer carries a compliance entry.
     expect(PAGE_SRC).not.toMatch(/^\s*compliance:\s*'/m);
-    // remediation + activity joined overview + compliance as live (non-stub) tabs.
+    // remediation + activity + audit_log joined overview + compliance as live tabs.
     expect(PAGE_SRC).toContain(
-      "Exclude<TabId, 'overview' | 'compliance' | 'remediation' | 'activity'>",
+      "Exclude<TabId, 'overview' | 'compliance' | 'remediation' | 'activity' | 'audit_log'>",
     );
   });
 

frontend/tests/pages/host-detail-shell.test.ts

@@ -490,7 +490,7 @@ describe('frontend-host-detail v1.6.0 — per-host credential management + recon
     expect(PAGE_SRC).toMatch(/activeTab === 'activity' \? \(\s*<HostActivityTab/);
     // The stub registry no longer carries an `activity` entry.
     expect(PAGE_SRC).not.toMatch(/activity:\s*'Unified Activity feed/);
-    expect(PAGE_SRC).toMatch(/Exclude<TabId, 'overview' \| 'compliance' \| 'remediation' \| 'activity'>/);
+    expect(PAGE_SRC).toMatch(/Exclude<TabId,[^>]*\| 'activity'[^>]*>/);
     // Paged host-scoped feed via useInfiniteQuery with cursor pagination.
     expect(PAGE_SRC).toContain('useInfiniteQuery');
     expect(PAGE_SRC).toMatch(/getNextPageParam:\s*\(last\)\s*=>\s*last\.next_cursor/);
@@ -499,7 +499,22 @@ describe('frontend-host-detail v1.6.0 — per-host credential management + recon
     expect(PAGE_SRC).toContain('HOST_ACTIVITY_SOURCES');
     expect(PAGE_SRC).toMatch(/hasNextPage/);
     expect(PAGE_SRC).toMatch(/Load more/);
-    // The Audit log tab remains a stub.
-    expect(PAGE_SRC).toMatch(/audit_log:\s*\n?\s*'Audit query API/);
+  });
+
+  // @ac AC-44
+  test('frontend-host-detail/AC-44 — Audit log tab is live (HostAuditLogTab), host-scoped + readable', () => {
+    expect(PAGE_SRC).toContain('function HostAuditLogTab');
+    expect(PAGE_SRC).toMatch(/activeTab === 'audit_log' \? \(\s*<HostAuditLogTab/);
+    // Removed from the deferred-stub registry.
+    expect(PAGE_SRC).not.toMatch(/audit_log:\s*\n?\s*'Audit query API/);
+    expect(PAGE_SRC).toMatch(
+      /Exclude<TabId, 'overview' \| 'compliance' \| 'remediation' \| 'activity' \| 'audit_log'>/,
+    );
+    // Host-scoped audit query + readable server message + audit:read gate.
+    expect(PAGE_SRC).toContain("'/api/v1/audit/events'");
+    expect(PAGE_SRC).toMatch(/resource_type:\s*'host'/);
+    expect(PAGE_SRC).toMatch(/resource_id:\s*hostId/);
+    expect(PAGE_SRC).toMatch(/it\.message \|\| it\.action/);
+    expect(PAGE_SRC).toMatch(/hasPermission\('audit:read'\)/);
   });
 });

internal/activity/format.go

@@ -54,11 +54,11 @@ func formatIntelligence(eventCode string, detail []byte) (title, summary string)
 	return title, intelSummary(detail)
 }
 
-// formatAudit renders an audit row as "<actor> <predicate>". The actor is
+// FormatAudit renders an audit row as "<actor> <predicate>". The actor is
 // the recorded actor_label, falling back to a readable actor_type. The raw
 // resource_id (a UUID) is intentionally NOT placed in the title; the
 // resource_type provides lightweight context in the summary.
-func formatAudit(action, actorLabel, actorType, resourceType string) (title, summary string) {
+func FormatAudit(action, actorLabel, actorType, resourceType string) (title, summary string) {
 	actor := strings.TrimSpace(actorLabel)
 	if actor == "" {
 		actor = actorWord(actorType)

internal/activity/format_test.go

@@ -45,15 +45,15 @@ func TestFormatters_HumanReadable(t *testing.T) {
 		}
 
 		// --- audit ---
-		title, summary = formatAudit("host.created", "alice@example.com", "user", "host")
+		title, summary = FormatAudit("host.created", "alice@example.com", "user", "host")
 		if title != "alice@example.com created a host" {
 			t.Errorf("audit title = %q", title)
 		}
 		if summary != "Host" {
 			t.Errorf("audit summary = %q, want Host", summary)
 		}
 		// actor_label empty -> readable actor_type; no UUID anywhere.
-		title, _ = formatAudit("authz.permission.denied", "", "system", "")
+		title, _ = FormatAudit("authz.permission.denied", "", "system", "")
 		if title != "System was denied permission" {
 			t.Errorf("audit fallback title = %q", title)
 		}
@@ -75,7 +75,7 @@ func TestFormatters_GracefulFallback(t *testing.T) {
 		}
 
 		// Unknown audit action.
-		title, _ = formatAudit("widget.frobnicated", "bob", "user", "")
+		title, _ = FormatAudit("widget.frobnicated", "bob", "user", "")
 		if containsDot(title) {
 			t.Errorf("audit title %q still contains a raw dotted code", title)
 		}

internal/activity/service.go

@@ -334,7 +334,7 @@ func (s *Service) queryUnion(ctx context.Context, f Filter, includeAlerts, inclu
 		case SourceIntelligence:
 			r.Title, r.Summary = formatIntelligence(code, detail)
 		case SourceAudit:
-			r.Title, r.Summary = formatAudit(code, ctxA, ctxB, ctxC)
+			r.Title, r.Summary = FormatAudit(code, ctxA, ctxB, ctxC)
 		}
 		out = append(out, r)
 	}