Add excluded_hosts feature: store in SQLite, expose CLI subcommands

Adds an excluded_host table to the SQLite schema and three new CLI
subcommands (exclude, unexclude, list-excluded) so operators can mark
hosts that are no longer expected to send updates. The IsExcludedHost
and LoadExcludedHosts storage helpers are ready for the Prometheus
alerting endpoint (task d4).

Co-Authored-By: Claude Sonnet 4.6 <noreply@anthropic.com>

1 files changed, 148 insertions, 0 deletions

diff --git a/internal/storage/excluded_host_test.go b/internal/storage/excluded_host_test.go
new file mode 100644
index 0000000..6af53a5
--- /dev/null
+++ b/internal/storage/excluded_host_test.go
@@ -0,0 +1,148 @@
+package storage
+
+import (
+	"context"
+	"path/filepath"
+	"testing"
+)
+
+func TestAddExcludedHost(t *testing.T) {
+	db, err := Open(context.Background(), filepath.Join(t.TempDir(), "test.db"))
+	if err != nil {
+		t.Fatal(err)
+	}
+	defer db.Close()
+	ctx := context.Background()
+	if err := CreateSchema(ctx, db); err != nil {
+		t.Fatal(err)
+	}
+	if err := AddExcludedHost(ctx, db, "host1", "decommissioned"); err != nil {
+		t.Fatal(err)
+	}
+	hosts, err := LoadExcludedHosts(ctx, db)
+	if err != nil {
+		t.Fatal(err)
+	}
+	if len(hosts) != 1 {
+		t.Fatalf("len=%d, want 1", len(hosts))
+	}
+	if hosts[0].Host != "host1" || hosts[0].Reason != "decommissioned" {
+		t.Fatalf("unexpected host entry: %+v", hosts[0])
+	}
+}
+
+func TestAddExcludedHost_idempotent(t *testing.T) {
+	db, err := Open(context.Background(), filepath.Join(t.TempDir(), "test.db"))
+	if err != nil {
+		t.Fatal(err)
+	}
+	defer db.Close()
+	ctx := context.Background()
+	if err := CreateSchema(ctx, db); err != nil {
+		t.Fatal(err)
+	}
+	if err := AddExcludedHost(ctx, db, "host1", "first"); err != nil {
+		t.Fatal(err)
+	}
+	if err := AddExcludedHost(ctx, db, "host1", "second"); err != nil {
+		t.Fatal(err)
+	}
+	hosts, err := LoadExcludedHosts(ctx, db)
+	if err != nil {
+		t.Fatal(err)
+	}
+	if len(hosts) != 1 {
+		t.Fatalf("len=%d, want 1", len(hosts))
+	}
+	if hosts[0].Reason != "second" {
+		t.Fatalf("reason=%q, want second", hosts[0].Reason)
+	}
+}
+
+func TestRemoveExcludedHost(t *testing.T) {
+	db, err := Open(context.Background(), filepath.Join(t.TempDir(), "test.db"))
+	if err != nil {
+		t.Fatal(err)
+	}
+	defer db.Close()
+	ctx := context.Background()
+	if err := CreateSchema(ctx, db); err != nil {
+		t.Fatal(err)
+	}
+	if err := AddExcludedHost(ctx, db, "host1", ""); err != nil {
+		t.Fatal(err)
+	}
+	if err := RemoveExcludedHost(ctx, db, "host1"); err != nil {
+		t.Fatal(err)
+	}
+	hosts, err := LoadExcludedHosts(ctx, db)
+	if err != nil {
+		t.Fatal(err)
+	}
+	if len(hosts) != 0 {
+		t.Fatalf("len=%d, want 0", len(hosts))
+	}
+}
+
+func TestRemoveExcludedHost_nonexistent(t *testing.T) {
+	db, err := Open(context.Background(), filepath.Join(t.TempDir(), "test.db"))
+	if err != nil {
+		t.Fatal(err)
+	}
+	defer db.Close()
+	ctx := context.Background()
+	if err := CreateSchema(ctx, db); err != nil {
+		t.Fatal(err)
+	}
+	if err := RemoveExcludedHost(ctx, db, "ghost"); err != nil {
+		t.Fatal(err)
+	}
+}
+
+func TestIsExcludedHost(t *testing.T) {
+	db, err := Open(context.Background(), filepath.Join(t.TempDir(), "test.db"))
+	if err != nil {
+		t.Fatal(err)
+	}
+	defer db.Close()
+	ctx := context.Background()
+	if err := CreateSchema(ctx, db); err != nil {
+		t.Fatal(err)
+	}
+	if err := AddExcludedHost(ctx, db, "host1", ""); err != nil {
+		t.Fatal(err)
+	}
+	yes, err := IsExcludedHost(ctx, db, "host1")
+	if err != nil {
+		t.Fatal(err)
+	}
+	if !yes {
+		t.Fatal("expected host1 to be excluded")
+	}
+	no, err := IsExcludedHost(ctx, db, "other")
+	if err != nil {
+		t.Fatal(err)
+	}
+	if no {
+		t.Fatal("expected other to not be excluded")
+	}
+}
+
+func TestLoadExcludedHosts_empty(t *testing.T) {
+	db, err := Open(context.Background(), filepath.Join(t.TempDir(), "test.db"))
+	if err != nil {
+		t.Fatal(err)
+	}
+	defer db.Close()
+	ctx := context.Background()
+	if err := CreateSchema(ctx, db); err != nil {
+		t.Fatal(err)
+	}
+	hosts, err := LoadExcludedHosts(ctx, db)
+	if err != nil {
+		t.Fatal(err)
+	}
+	if len(hosts) != 0 {
+		t.Fatalf("len=%d, want 0", len(hosts))
+	}
+}