feat: add header options to text panel

#### Description

- A PromQL subquery without a step, for example
`max_over_time(metric[5m:])`, segfaulted the whole query-service. The
engine calls `NoStepSubqueryIntervalFn` for such subqueries, and we
build the engine without it, so the call hits a nil function.
- The bug is present on every PromQL surface, because all of them share
the one engine constructor in `pkg/prometheus/engine.go`: v3 and v5
`query_range`, `/api/v1/query`, the clickhousev2 transpiler, and promql
alert rules. A saved rule with such a subquery crash-loops the instance
on its own schedule.
- The fix sets the callback to 1m. This matches the Prometheus default
global `evaluation_interval`, which upstream wires into this field. One
place fixes every path.
- This is the root cause of the SigNoz/platform-pod#3068 incident. The
instance-hardening request from that incident is tracked in
SigNoz/pulse-pod#308.

#### Issues closed by this PR

Closes SigNoz/platform-pod#3068

#### Additional Information

We audited `EngineOpts` for more bugs of the same class.
`NoStepSubqueryIntervalFn` is the only field the engine calls without a
nil guard; `promql.NewEngine` defaults the other nil-able fields
(`Parser`, `FeatureRegistry`). The remaining gaps against upstream
wiring are not crashes, and we filed them separately:
SigNoz/pulse-pod#305 (`@` modifier and negative offset disabled),
SigNoz/pulse-pod#306 (engine self-metrics not registered),
SigNoz/pulse-pod#307 (active query tracker startup panic risk),
SigNoz/pulse-pod#309 (step guard in the v3 cache), SigNoz/pulse-pod#310
(upstream proposal to fail fast on the nil callback).

Tests for the bug:

- `pkg/prometheus/engine_test.go` — fails with the exact segfault when
the fix is removed.
- `tests/integration/tests/promqlconformance/04_no_step_subquery.py` — a
step-less subquery through `/api/v5/query_range` returns correct values
on both providers, and the service stays up.
- `tests/integration/tests/alerts/04_promql_subquery_no_step.py` — a
promql alert rule with a step-less subquery evaluates and fires.

🤖 Generated with [Claude Code](https://claude.com/claude-code)

docs/api/openapi.yml

@@ -2944,6 +2944,11 @@ components:
         publicDashboard:
           $ref: '#/components/schemas/DashboardtypesGettablePublicDasbhboard'
       type: object
+    DashboardtypesHeaderOptions:
+      properties:
+        hide:
+          type: boolean
+      type: object
     DashboardtypesHistogramBuckets:
       properties:
         bucketCount:
@@ -3281,6 +3286,11 @@ components:
       - kind
       - spec
       type: object
+    DashboardtypesPanelBackground:
+      enum:
+      - solid
+      - transparent
+      type: string
     DashboardtypesPanelFormatting:
       properties:
         decimalPrecision:
@@ -3301,6 +3311,7 @@ components:
           signoz/NumberPanel: '#/components/schemas/DashboardtypesPanelPluginVariantGithubComSigNozSignozPkgTypesDashboardtypesNumberPanelSpec'
           signoz/PieChartPanel: '#/components/schemas/DashboardtypesPanelPluginVariantGithubComSigNozSignozPkgTypesDashboardtypesPieChartPanelSpec'
           signoz/TablePanel: '#/components/schemas/DashboardtypesPanelPluginVariantGithubComSigNozSignozPkgTypesDashboardtypesTablePanelSpec'
+          signoz/TextPanel: '#/components/schemas/DashboardtypesPanelPluginVariantGithubComSigNozSignozPkgTypesDashboardtypesTextPanelSpec'
           signoz/TimeSeriesPanel: '#/components/schemas/DashboardtypesPanelPluginVariantGithubComSigNozSignozPkgTypesDashboardtypesTimeSeriesPanelSpec'
         propertyName: kind
       oneOf:
@@ -3311,6 +3322,7 @@ components:
       - $ref: '#/components/schemas/DashboardtypesPanelPluginVariantGithubComSigNozSignozPkgTypesDashboardtypesTablePanelSpec'
       - $ref: '#/components/schemas/DashboardtypesPanelPluginVariantGithubComSigNozSignozPkgTypesDashboardtypesHistogramPanelSpec'
       - $ref: '#/components/schemas/DashboardtypesPanelPluginVariantGithubComSigNozSignozPkgTypesDashboardtypesListPanelSpec'
+      - $ref: '#/components/schemas/DashboardtypesPanelPluginVariantGithubComSigNozSignozPkgTypesDashboardtypesTextPanelSpec'
       type: object
     DashboardtypesPanelPluginKind:
       enum:
@@ -3321,6 +3333,7 @@ components:
       - signoz/TablePanel
       - signoz/HistogramPanel
       - signoz/ListPanel
+      - signoz/TextPanel
       type: string
     DashboardtypesPanelPluginVariantGithubComSigNozSignozPkgTypesDashboardtypesBarChartPanelSpec:
       properties:
@@ -3394,6 +3407,18 @@ components:
       - kind
       - spec
       type: object
+    DashboardtypesPanelPluginVariantGithubComSigNozSignozPkgTypesDashboardtypesTextPanelSpec:
+      properties:
+        kind:
+          enum:
+          - signoz/TextPanel
+          type: string
+        spec:
+          $ref: '#/components/schemas/DashboardtypesTextPanelSpec'
+      required:
+      - kind
+      - spec
+      type: object
     DashboardtypesPanelPluginVariantGithubComSigNozSignozPkgTypesDashboardtypesTimeSeriesPanelSpec:
       properties:
         kind:
@@ -3685,6 +3710,36 @@ components:
       - color
       - columnName
       type: object
+    DashboardtypesTextAlign:
+      enum:
+      - left
+      - center
+      - right
+      type: string
+    DashboardtypesTextMode:
+      enum:
+      - markdown
+      type: string
+    DashboardtypesTextPanelSpec:
+      properties:
+        headerOptions:
+          $ref: '#/components/schemas/DashboardtypesHeaderOptions'
+        mode:
+          $ref: '#/components/schemas/DashboardtypesTextMode'
+        presentation:
+          $ref: '#/components/schemas/DashboardtypesTextPresentation'
+        text:
+          type: string
+      type: object
+    DashboardtypesTextPresentation:
+      properties:
+        background:
+          $ref: '#/components/schemas/DashboardtypesPanelBackground'
+        textAlign:
+          $ref: '#/components/schemas/DashboardtypesTextAlign'
+        verticalAlign:
+          $ref: '#/components/schemas/DashboardtypesVerticalAlign'
+      type: object
     DashboardtypesTextVariableSpec:
       properties:
         constant:
@@ -3894,6 +3949,12 @@ components:
       - kind
       - spec
       type: object
+    DashboardtypesVerticalAlign:
+      enum:
+      - top
+      - center
+      - bottom
+      type: string
     ErrorsJSON:
       properties:
         code:

pkg/prometheus/engine.go

@@ -2,6 +2,7 @@ package prometheus
 
 import (
 	"log/slog"
+	"time"
 
 	"github.com/prometheus/prometheus/promql"
 )
@@ -23,5 +24,11 @@ func NewEngine(logger *slog.Logger, cfg Config) *Engine {
 		Timeout:            cfg.Timeout,
 		ActiveQueryTracker: activeQueryTracker,
 		LookbackDelta:      cfg.LookbackDelta,
+		// The engine calls this for subqueries that do not set a step, such as
+		// `metric[5m:]`, and segfaults if it is nil. 1m matches the default
+		// global evaluation_interval that Prometheus wires here.
+		NoStepSubqueryIntervalFn: func(int64) int64 {
+			return time.Minute.Milliseconds()
+		},
 	})
 }

pkg/prometheus/engine_test.go

@@ -0,0 +1,33 @@
+package prometheus
+
+import (
+	"context"
+	"log/slog"
+	"testing"
+	"time"
+
+	"github.com/prometheus/prometheus/storage"
+	"github.com/stretchr/testify/require"
+)
+
+func TestNoStepSubqueryDoesNotPanic(t *testing.T) {
+	engine := NewEngine(slog.New(slog.DiscardHandler), Config{Timeout: time.Minute})
+	queryable := storage.QueryableFunc(func(int64, int64) (storage.Querier, error) {
+		return storage.NoopQuerier(), nil
+	})
+
+	qry, err := engine.NewRangeQuery(
+		context.Background(),
+		queryable,
+		nil,
+		"max_over_time(some_metric[5m:])",
+		time.Now().Add(-time.Hour),
+		time.Now(),
+		time.Minute,
+	)
+	require.NoError(t, err)
+	defer qry.Close()
+
+	res := qry.Exec(context.Background())
+	require.NoError(t, res.Err)
+}

pkg/types/dashboardtypes/perses_dashboard_data.go

@@ -114,8 +114,8 @@ func (d *DashboardSpec) validatePanels() error {
 			return err
 		}
 		panelKind := panel.Spec.Plugin.Kind
-		if len(panel.Spec.Queries) != 1 {
-			return errors.NewInvalidInputf(ErrCodeDashboardInvalidInput, "%s.spec.queries: panel must have one query, found %d", path, len(panel.Spec.Queries))
+		if err := validatePanelQueryCount(panel.Spec.Queries, panelKind, path); err != nil {
+			return err
 		}
 		allowed := allowedQueryKinds[panelKind]
 		for qi, q := range panel.Spec.Queries {
@@ -127,6 +127,22 @@ func (d *DashboardSpec) validatePanels() error {
 	return nil
 }
 
+func validatePanelQueryCount(queries []Query, panelKind PanelPluginKind, path string) error {
+	if queries == nil {
+		return errors.NewInvalidInputf(ErrCodeDashboardInvalidInput, "%s.spec.queries: is required and must not be null; use [] for a panel that renders without a query", path)
+	}
+	if panelKind.rendersWithoutQuery() {
+		if len(queries) != 0 {
+			return errors.NewInvalidInputf(ErrCodeDashboardInvalidInput, "%s.spec.queries: panel kind %q renders without a query and must have queries: [], found %d", path, panelKind, len(queries))
+		}
+		return nil
+	}
+	if len(queries) != 1 {
+		return errors.NewInvalidInputf(ErrCodeDashboardInvalidInput, "%s.spec.queries: panel must have one query, found %d", path, len(queries))
+	}
+	return nil
+}
+
 func (d *DashboardSpec) validateQuery(qi int, q Query, panelKind PanelPluginKind, path string, allowed []QueryPluginKind) error {
 	queryPath := fmt.Sprintf("%s.spec.queries[%d].spec.plugin", path, qi)
 	if err := validateQueryAllowedForPanel(q.Spec.Plugin, allowed, panelKind, queryPath); err != nil {

pkg/types/dashboardtypes/perses_dashboard_test.go

@@ -1085,7 +1085,7 @@ func TestInvalidatePanelWithoutQueries(t *testing.T) {
 	}`)
 	_, err := unmarshalDashboard(data)
 	require.Error(t, err, "expected panel-without-queries to be rejected")
-	assert.Contains(t, err.Error(), "panel must have one query")
+	assert.Contains(t, err.Error(), "spec.queries: is required and must not be null")
 }
 
 func TestInvalidatePanelWithEmptyQueriesArray(t *testing.T) {
@@ -1135,6 +1135,126 @@ func TestInvalidatePanelWithMultipleDirectQueries(t *testing.T) {
 	assert.Contains(t, err.Error(), "panel must have one query")
 }
 
+func TestValidateTextPanel(t *testing.T) {
+	wrapPanel := func(panelSpec string) []byte {
+		return []byte(`{
+			"variables": [],
+			"panels": {
+				"p1": {
+					"kind": "Panel",
+					"spec": {
+						"links": [],
+						"plugin": {"kind": "signoz/TextPanel", "spec": ` + panelSpec + `},
+						"queries": []
+					}
+				}
+			},
+			"links": [],
+			"layouts": []
+		}`)
+	}
+
+	t.Run("fully specified text panel validates", func(t *testing.T) {
+		d, err := unmarshalDashboard(wrapPanel(`{
+			"mode": "markdown",
+			"text": "# Runbook\n\nSee the [oncall doc](https://example.com).",
+			"presentation": {"textAlign": "center", "verticalAlign": "bottom", "background": "transparent"},
+			"headerOptions": {"hide": true}
+		}`))
+		require.NoError(t, err, "expected a fully specified text panel to validate")
+
+		spec, ok := d.Panels["p1"].Spec.Plugin.Spec.(*TextPanelSpec)
+		require.True(t, ok, "expected the panel spec to decode as *TextPanelSpec")
+		assert.Equal(t, TextModeMarkdown, spec.Mode)
+		assert.Equal(t, "# Runbook\n\nSee the [oncall doc](https://example.com).", spec.Text)
+		assert.Equal(t, TextAlignCenter, spec.Presentation.TextAlign)
+		assert.Equal(t, VerticalAlignBottom, spec.Presentation.VerticalAlign)
+		assert.Equal(t, PanelBackgroundTransparent, spec.Presentation.Background)
+		assert.True(t, spec.HeaderOptions.Hide)
+	})
+
+	// The header shows unless explicitly hidden, so the zero value must round-trip
+	// as a shown header.
+	t.Run("omitted fields marshal back as their defaults", func(t *testing.T) {
+		d, err := unmarshalDashboard(wrapPanel(`{}`))
+		require.NoError(t, err, "expected an empty text panel spec to validate")
+
+		out, err := json.Marshal(d.Panels["p1"].Spec.Plugin.Spec)
+		require.NoError(t, err, "marshalling the decoded text panel spec")
+		assert.JSONEq(t, `{
+			"mode": "markdown",
+			"text": "",
+			"presentation": {"textAlign": "left", "verticalAlign": "top", "background": "solid"},
+			"headerOptions": {"hide": false}
+		}`, string(out))
+	})
+
+	t.Run("a text panel carrying a query is rejected", func(t *testing.T) {
+		data := []byte(`{
+			"variables": [],
+			"panels": {
+				"p1": {
+					"kind": "Panel",
+					"spec": {
+						"links": [],
+						"plugin": {"kind": "signoz/TextPanel", "spec": {"text": "hi"}},
+						"queries": [{"kind": "time_series", "spec": {"plugin": {"kind": "signoz/BuilderQuery", "spec": {"name": "A", "signal": "metrics"}}}}]
+					}
+				}
+			},
+			"links": [],
+			"layouts": []
+		}`)
+		_, err := unmarshalDashboard(data)
+		require.Error(t, err, "expected a text panel with a query to be rejected")
+		assert.Contains(t, err.Error(), "renders without a query and must have queries: [], found 1")
+	})
+
+	t.Run("a text panel with null queries is rejected", func(t *testing.T) {
+		data := []byte(`{
+			"variables": [],
+			"panels": {
+				"p1": {
+					"kind": "Panel",
+					"spec": {
+						"links": [],
+						"plugin": {"kind": "signoz/TextPanel", "spec": {"text": "hi"}},
+						"queries": null
+					}
+				}
+			},
+			"links": [],
+			"layouts": []
+		}`)
+		_, err := unmarshalDashboard(data)
+		require.Error(t, err, "expected a text panel with null queries to be rejected")
+		assert.Contains(t, err.Error(), "spec.queries: is required and must not be null")
+	})
+
+	t.Run("unknown enum values are rejected", func(t *testing.T) {
+		for field, spec := range map[string]string{
+			"mode":          `{"mode": "html"}`,
+			"textAlign":     `{"presentation": {"textAlign": "justify"}}`,
+			"verticalAlign": `{"presentation": {"verticalAlign": "middle"}}`,
+			"background":    `{"presentation": {"background": "blurred"}}`,
+		} {
+			_, err := unmarshalDashboard(wrapPanel(spec))
+			assert.Error(t, err, "expected an unknown %s value to be rejected", field)
+		}
+	})
+
+	t.Run("unknown spec fields are rejected", func(t *testing.T) {
+		for field, spec := range map[string]string{
+			"top level":     `{"markdown": "hi"}`,
+			"presentation":  `{"presentation": {"horizontalAlign": "left"}}`,
+			"headerOptions": `{"headerOptions": {"show": true}}`,
+		} {
+			_, err := unmarshalDashboard(wrapPanel(spec))
+			assert.Error(t, err, "expected an unknown %s field to be rejected", field)
+		}
+	})
+}
+
 func TestValidateRequiredFields(t *testing.T) {
 	wrapVariable := func(pluginKind, pluginSpec string) string {
 		return `{

pkg/types/dashboardtypes/perses_plugin_wrappers.go

@@ -35,6 +35,7 @@ func (PanelPlugin) PrepareJSONSchema(s *jsonschema.Schema) error {
 		string(PanelKindTable):      schemaRef("DashboardtypesPanelPluginVariantGithubComSigNozSignozPkgTypesDashboardtypesTablePanelSpec"),
 		string(PanelKindHistogram):  schemaRef("DashboardtypesPanelPluginVariantGithubComSigNozSignozPkgTypesDashboardtypesHistogramPanelSpec"),
 		string(PanelKindList):       schemaRef("DashboardtypesPanelPluginVariantGithubComSigNozSignozPkgTypesDashboardtypesListPanelSpec"),
+		string(PanelKindText):       schemaRef("DashboardtypesPanelPluginVariantGithubComSigNozSignozPkgTypesDashboardtypesTextPanelSpec"),
 	})
 }
 
@@ -65,6 +66,7 @@ func (PanelPlugin) JSONSchemaOneOf() []any {
 		PanelPluginVariant[TablePanelSpec]{Kind: string(PanelKindTable)},
 		PanelPluginVariant[HistogramPanelSpec]{Kind: string(PanelKindHistogram)},
 		PanelPluginVariant[ListPanelSpec]{Kind: string(PanelKindList)},
+		PanelPluginVariant[TextPanelSpec]{Kind: string(PanelKindText)},
 	}
 }
 
@@ -228,6 +230,7 @@ var (
 		PanelKindTable:      func() any { return new(TablePanelSpec) },
 		PanelKindHistogram:  func() any { return new(HistogramPanelSpec) },
 		PanelKindList:       func() any { return new(ListPanelSpec) },
+		PanelKindText:       func() any { return new(TextPanelSpec) },
 	}
 	queryPluginSpecs = map[QueryPluginKind]func() any{
 		QueryKindBuilder:       func() any { return new(BuilderQuerySpec) },
@@ -250,6 +253,7 @@ var (
 		PanelKindPieChart:   {QueryKindBuilder, QueryKindComposite, QueryKindFormula, QueryKindTraceOperator, QueryKindClickHouseSQL},
 		PanelKindTable:      {QueryKindBuilder, QueryKindComposite, QueryKindFormula, QueryKindTraceOperator, QueryKindClickHouseSQL},
 		PanelKindList:       {QueryKindBuilder},
+		PanelKindText:       {},
 	}
 )
 

pkg/types/dashboardtypes/perses_public_dashboard.go

@@ -172,7 +172,12 @@ func (d *DashboardV2) GetPanelQuery(startTime, endTime uint64, panelKey string)
 	if !ok || panel == nil {
 		return nil, errors.Newf(errors.TypeInvalidInput, ErrCodeDashboardInvalidInput, "panel with key %q doesn't exist", panelKey)
 	}
-	// Validator guarantees exactly one query per panel.
+	// A panel kind that renders from its own plugin spec has no query to execute;
+	// asking for its query range is a client mistake.
+	if panel.Spec.Plugin.Kind.rendersWithoutQuery() {
+		return nil, errors.Newf(errors.TypeInvalidInput, ErrCodeDashboardInvalidWidgetQuery, "panel %q is a %q and has no query to execute", panelKey, panel.Spec.Plugin.Kind)
+	}
+	// Validator guarantees exactly one query for every other panel kind.
 	if len(panel.Spec.Queries) != 1 {
 		return nil, errors.Newf(errors.TypeInvalidInput, ErrCodeDashboardInvalidWidgetQuery, "panel %q must have exactly one query", panelKey)
 	}

pkg/types/dashboardtypes/perses_signoz_plugins.go

@@ -173,10 +173,15 @@ const (
 	PanelKindTable      PanelPluginKind = "signoz/TablePanel"
 	PanelKindHistogram  PanelPluginKind = "signoz/HistogramPanel"
 	PanelKindList       PanelPluginKind = "signoz/ListPanel"
+	PanelKindText       PanelPluginKind = "signoz/TextPanel"
 )
 
 func (PanelPluginKind) Enum() []any {
-	return []any{PanelKindTimeSeries, PanelKindBarChart, PanelKindNumber, PanelKindPieChart, PanelKindTable, PanelKindHistogram, PanelKindList}
+	return []any{PanelKindTimeSeries, PanelKindBarChart, PanelKindNumber, PanelKindPieChart, PanelKindTable, PanelKindHistogram, PanelKindList, PanelKindText}
+}
+
+func (k PanelPluginKind) rendersWithoutQuery() bool {
+	return k == PanelKindText
 }
 
 type TimeSeriesPanelSpec struct {
@@ -237,6 +242,19 @@ type ListPanelSpec struct {
 	SelectFields []telemetrytypes.TelemetryFieldKey `json:"selectFields,omitzero" validate:"dive"`
 }
 
+type TextPanelSpec struct {
+	Mode          TextMode         `json:"mode"`
+	Text          string           `json:"text"`
+	Presentation  TextPresentation `json:"presentation"`
+	HeaderOptions HeaderOptions    `json:"headerOptions"`
+}
+
+type TextPresentation struct {
+	TextAlign     TextAlign       `json:"textAlign"`
+	VerticalAlign VerticalAlign   `json:"verticalAlign"`
+	Background    PanelBackground `json:"background"`
+}
+
 // ══════════════════════════════════════════════
 // Panel common types
 // ══════════════════════════════════════════════
@@ -247,6 +265,13 @@ type Axes struct {
 	IsLogScale bool     `json:"isLogScale"`
 }
 
+// HeaderOptions controls the panel card's header strip — the title/description
+// row above the panel content. Phrased as hide so the zero value shows the
+// header, matching every other panel kind.
+type HeaderOptions struct {
+	Hide bool `json:"hide"`
+}
+
 type BasicVisualization struct {
 	TimePreference TimePreference `json:"timePreference"`
 }
@@ -658,6 +683,157 @@ func (sg SpanGaps) validate() error {
 	return nil
 }
 
+// TextMode is how a text panel interprets its `text`. Only markdown is
+// rendered today; further modes (e.g. plain text, HTML) are expected.
+type TextMode struct{ valuer.String }
+
+var TextModeMarkdown = TextMode{valuer.NewString("markdown")} // default
+
+func (TextMode) Enum() []any {
+	return []any{TextModeMarkdown}
+}
+
+func (m TextMode) ValueOrDefault() string {
+	if m.IsZero() {
+		return TextModeMarkdown.StringValue()
+	}
+	return m.StringValue()
+}
+
+func (m TextMode) MarshalJSON() ([]byte, error) {
+	return json.Marshal(m.ValueOrDefault())
+}
+
+func (m *TextMode) UnmarshalJSON(data []byte) error {
+	var v string
+	if err := json.Unmarshal(data, &v); err != nil {
+		return errors.WrapInvalidInputf(err, ErrCodeDashboardInvalidInput, "invalid text mode: must be the string `markdown`")
+	}
+	tm := TextMode{valuer.NewString(v)}
+	switch tm {
+	case TextModeMarkdown:
+		*m = tm
+		return nil
+	default:
+		return errors.NewInvalidInputf(ErrCodeDashboardInvalidInput, "invalid text mode %q: must be `markdown`", v)
+	}
+}
+
+type TextAlign struct{ valuer.String }
+
+var (
+	TextAlignLeft   = TextAlign{valuer.NewString("left")} // default
+	TextAlignCenter = TextAlign{valuer.NewString("center")}
+	TextAlignRight  = TextAlign{valuer.NewString("right")}
+)
+
+func (TextAlign) Enum() []any {
+	return []any{TextAlignLeft, TextAlignCenter, TextAlignRight}
+}
+
+func (a TextAlign) ValueOrDefault() string {
+	if a.IsZero() {
+		return TextAlignLeft.StringValue()
+	}
+	return a.StringValue()
+}
+
+func (a TextAlign) MarshalJSON() ([]byte, error) {
+	return json.Marshal(a.ValueOrDefault())
+}
+
+func (a *TextAlign) UnmarshalJSON(data []byte) error {
+	var v string
+	if err := json.Unmarshal(data, &v); err != nil {
+		return errors.WrapInvalidInputf(err, ErrCodeDashboardInvalidInput, "invalid text align: must be a string, one of `left`, `center`, or `right`")
+	}
+	val := TextAlign{valuer.NewString(v)}
+	switch val {
+	case TextAlignLeft, TextAlignCenter, TextAlignRight:
+		*a = val
+		return nil
+	default:
+		return errors.NewInvalidInputf(ErrCodeDashboardInvalidInput, "invalid text align %q: must be `left`, `center`, or `right`", v)
+	}
+}
+
+type VerticalAlign struct{ valuer.String }
+
+var (
+	VerticalAlignTop    = VerticalAlign{valuer.NewString("top")} // default
+	VerticalAlignCenter = VerticalAlign{valuer.NewString("center")}
+	VerticalAlignBottom = VerticalAlign{valuer.NewString("bottom")}
+)
+
+func (VerticalAlign) Enum() []any {
+	return []any{VerticalAlignTop, VerticalAlignCenter, VerticalAlignBottom}
+}
+
+func (a VerticalAlign) ValueOrDefault() string {
+	if a.IsZero() {
+		return VerticalAlignTop.StringValue()
+	}
+	return a.StringValue()
+}
+
+func (a VerticalAlign) MarshalJSON() ([]byte, error) {
+	return json.Marshal(a.ValueOrDefault())
+}
+
+func (a *VerticalAlign) UnmarshalJSON(data []byte) error {
+	var v string
+	if err := json.Unmarshal(data, &v); err != nil {
+		return errors.WrapInvalidInputf(err, ErrCodeDashboardInvalidInput, "invalid vertical align: must be a string, one of `top`, `center`, or `bottom`")
+	}
+	val := VerticalAlign{valuer.NewString(v)}
+	switch val {
+	case VerticalAlignTop, VerticalAlignCenter, VerticalAlignBottom:
+		*a = val
+		return nil
+	default:
+		return errors.NewInvalidInputf(ErrCodeDashboardInvalidInput, "invalid vertical align %q: must be `top`, `center`, or `bottom`", v)
+	}
+}
+
+// PanelBackground selects the panel's surface: `solid` draws the standard panel
+// card, `transparent` drops the card so only the content shows.
+type PanelBackground struct{ valuer.String }
+
+var (
+	PanelBackgroundSolid       = PanelBackground{valuer.NewString("solid")} // default
+	PanelBackgroundTransparent = PanelBackground{valuer.NewString("transparent")}
+)
+
+func (PanelBackground) Enum() []any {
+	return []any{PanelBackgroundSolid, PanelBackgroundTransparent}
+}
+
+func (b PanelBackground) ValueOrDefault() string {
+	if b.IsZero() {
+		return PanelBackgroundSolid.StringValue()
+	}
+	return b.StringValue()
+}
+
+func (b PanelBackground) MarshalJSON() ([]byte, error) {
+	return json.Marshal(b.ValueOrDefault())
+}
+
+func (b *PanelBackground) UnmarshalJSON(data []byte) error {
+	var v string
+	if err := json.Unmarshal(data, &v); err != nil {
+		return errors.WrapInvalidInputf(err, ErrCodeDashboardInvalidInput, "invalid background: must be a string, one of `solid` or `transparent`")
+	}
+	val := PanelBackground{valuer.NewString(v)}
+	switch val {
+	case PanelBackgroundSolid, PanelBackgroundTransparent:
+		*b = val
+		return nil
+	default:
+		return errors.NewInvalidInputf(ErrCodeDashboardInvalidInput, "invalid background %q: must be `solid` or `transparent`", v)
+	}
+}
+
 type PrecisionOption struct{ valuer.String }
 
 var (

tests/integration/testdata/alerts/test_scenarios/promql_subquery_no_step/alert_data.jsonl

@@ -0,0 +1,5 @@
+{"metric_name":"cpu_percent_promql_subquery_no_step","labels":{"host":"server-01","cpu":"cpu0"},"timestamp":"2026-01-29T10:01:00+00:00","value":15,"temporality":"Unspecified","type_":"Gauge","is_monotonic":false,"flags":0,"description":"","unit":"","env":"default","resource_attrs":{},"scope_attrs":{}}
+{"metric_name":"cpu_percent_promql_subquery_no_step","labels":{"host":"server-01","cpu":"cpu0"},"timestamp":"2026-01-29T10:02:00+00:00","value":15,"temporality":"Unspecified","type_":"Gauge","is_monotonic":false,"flags":0,"description":"","unit":"","env":"default","resource_attrs":{},"scope_attrs":{}}
+{"metric_name":"cpu_percent_promql_subquery_no_step","labels":{"host":"server-01","cpu":"cpu0"},"timestamp":"2026-01-29T10:03:00+00:00","value":15,"temporality":"Unspecified","type_":"Gauge","is_monotonic":false,"flags":0,"description":"","unit":"","env":"default","resource_attrs":{},"scope_attrs":{}}
+{"metric_name":"cpu_percent_promql_subquery_no_step","labels":{"host":"server-01","cpu":"cpu0"},"timestamp":"2026-01-29T10:04:00+00:00","value":15,"temporality":"Unspecified","type_":"Gauge","is_monotonic":false,"flags":0,"description":"","unit":"","env":"default","resource_attrs":{},"scope_attrs":{}}
+{"metric_name":"cpu_percent_promql_subquery_no_step","labels":{"host":"server-01","cpu":"cpu0"},"timestamp":"2026-01-29T10:05:00+00:00","value":15,"temporality":"Unspecified","type_":"Gauge","is_monotonic":false,"flags":0,"description":"","unit":"","env":"default","resource_attrs":{},"scope_attrs":{}}

tests/integration/testdata/alerts/test_scenarios/promql_subquery_no_step/rule.json

@@ -0,0 +1,58 @@
+{
+  "alert": "promql_subquery_no_step",
+  "ruleType": "promql_rule",
+  "alertType": "METRIC_BASED_ALERT",
+  "condition": {
+    "thresholds": {
+      "kind": "basic",
+      "spec": [
+        {
+          "name": "critical",
+          "target": 10,
+          "matchType": "at_least_once",
+          "op": "above",
+          "channels": [
+            "test channel"
+          ]
+        }
+      ]
+    },
+    "compositeQuery": {
+      "queryType": "promql",
+      "panelType": "graph",
+      "queries": [
+        {
+          "type": "promql",
+          "spec": {
+            "name": "A",
+            "query": "max_over_time({\"cpu_percent_promql_subquery_no_step\"}[2m:])"
+          }
+        }
+      ]
+    },
+    "selectedQueryName": "A"
+  },
+  "evaluation": {
+    "kind": "rolling",
+    "spec": {
+      "evalWindow": "5m0s",
+      "frequency": "15s"
+    }
+  },
+  "labels": {},
+  "annotations": {
+    "description": "This alert is fired when the defined metric (current value: {{$value}}) crosses the threshold ({{$threshold}})",
+    "summary": "This alert is fired when the defined metric (current value: {{$value}}) crosses the threshold ({{$threshold}})"
+  },
+  "notificationSettings": {
+    "groupBy": [],
+    "usePolicy": false,
+    "renotify": {
+      "enabled": false,
+      "interval": "30m",
+      "alertStates": []
+    }
+  },
+  "version": "v5",
+  "schemaVersion": "v2alpha1"
+}

tests/integration/tests/alerts/04_promql_subquery_no_step.py

@@ -0,0 +1,93 @@
+import json
+import uuid
+from collections.abc import Callable
+from datetime import UTC, datetime, timedelta
+
+from wiremock.client import HttpMethods, Mapping, MappingRequest, MappingResponse
+
+from fixtures import types
+from fixtures.alerts import (
+    update_rule_channel_name,
+    verify_webhook_alert_expectation,
+)
+from fixtures.fs import get_testdata_file_path
+
+TEST_CASE = types.AlertTestCase(
+    name="promql_subquery_no_step",
+    rule_path="alerts/test_scenarios/promql_subquery_no_step/rule.json",
+    alert_data=[
+        types.AlertData(
+            type="metrics",
+            data_path="alerts/test_scenarios/promql_subquery_no_step/alert_data.jsonl",
+        ),
+    ],
+    alert_expectation=types.AlertExpectation(
+        should_alert=True,
+        wait_time_seconds=30,
+        expected_alerts=[
+            types.FiringAlert(
+                labels={
+                    "alertname": "promql_subquery_no_step",
+                    "threshold.name": "critical",
+                }
+            ),
+        ],
+    ),
+)
+
+
+def test_promql_rule_subquery_without_step(
+    notification_channel: types.TestContainerDocker,
+    make_http_mocks: Callable[[types.TestContainerDocker, list[Mapping]], None],
+    create_webhook_notification_channel: Callable[[str, str, dict, bool], str],
+    create_alert_rule: Callable[[dict], str],
+    insert_alert_data: Callable[[list[types.AlertData], datetime], None],
+):
+    """
+    A promql rule with a step-less subquery ([2m:]) must evaluate and fire.
+    A nil NoStepSubqueryIntervalFn segfaults the process on first evaluation.
+    """
+    notification_channel_name = str(uuid.uuid4())
+    webhook_endpoint_path = f"/alert/{notification_channel_name}"
+    notification_url = notification_channel.container_configs["8080"].get(webhook_endpoint_path)
+
+    make_http_mocks(
+        notification_channel,
+        [
+            Mapping(
+                request=MappingRequest(
+                    method=HttpMethods.POST,
+                    url=webhook_endpoint_path,
+                ),
+                response=MappingResponse(
+                    status=200,
+                    json_body={},
+                ),
+                persistent=False,
+            )
+        ],
+    )
+
+    create_webhook_notification_channel(
+        channel_name=notification_channel_name,
+        webhook_url=notification_url,
+        http_config={},
+        send_resolved=False,
+    )
+
+    insert_alert_data(
+        TEST_CASE.alert_data,
+        base_time=datetime.now(tz=UTC) - timedelta(minutes=5),
+    )
+
+    rule_path = get_testdata_file_path(TEST_CASE.rule_path)
+    with open(rule_path, encoding="utf-8") as f:
+        rule_data = json.loads(f.read())
+    update_rule_channel_name(rule_data, notification_channel_name)
+    create_alert_rule(rule_data)
+
+    verify_webhook_alert_expectation(
+        notification_channel,
+        notification_channel_name,
+        TEST_CASE.alert_expectation,
+    )

tests/integration/tests/promqlconformance/04_no_step_subquery.py

@@ -0,0 +1,65 @@
+from collections.abc import Callable
+from datetime import UTC, datetime, timedelta
+from http import HTTPStatus
+from uuid import uuid4
+
+from fixtures import types
+from fixtures.auth import USER_ADMIN_EMAIL, USER_ADMIN_PASSWORD
+from fixtures.metrics import Metrics
+from fixtures.querier import get_all_series, make_query_request
+
+MINUTE_MS = 60_000
+
+LEGS: list[tuple[str, dict | None]] = [
+    ("default", None),
+    ("clickhousev2", {"X-SigNoz-PromQL-Provider": "clickhousev2"}),
+]
+
+
+def test_promql_subquery_without_step_evaluates(
+    signoz: types.SigNoz,
+    create_user_admin: None,  # pylint: disable=unused-argument
+    get_token: Callable[[str, str], str],
+    insert_metrics: Callable[[list[Metrics]], None],
+) -> None:
+    """
+    A subquery that omits its step, e.g. `metric[5m:]`, is valid PromQL: the
+    engine fills in its default resolution. A nil NoStepSubqueryIntervalFn
+    segfaults the whole process on the first such query.
+    """
+    end_ms = (int((datetime.now(tz=UTC) - timedelta(minutes=5)).timestamp() * 1000) // MINUTE_MS) * MINUTE_MS
+    start_ms = end_ms - 30 * MINUTE_MS
+
+    metric = f"no_step_subquery_gauge_{uuid4().hex[:8]}"
+    insert_metrics(
+        [
+            Metrics(
+                metric_name=metric,
+                labels={"host": "server-01"},
+                timestamp=datetime.fromtimestamp(ts_ms / 1000, tz=UTC),
+                value=42.0,
+            )
+            for ts_ms in range(start_ms, end_ms + 1, MINUTE_MS)
+        ]
+    )
+
+    token = get_token(USER_ADMIN_EMAIL, USER_ADMIN_PASSWORD)
+
+    for leg, headers in LEGS:
+        query = {"type": "promql", "spec": {"name": "A", "query": f"max_over_time({metric}[5m:])"}}
+        response = make_query_request(signoz, token, start_ms, end_ms, [query], headers=headers)
+        assert response.status_code == HTTPStatus.OK, f"{leg}: {response.text[:300]}"
+        series = get_all_series(response.json(), "A")
+        assert series, f"{leg}: the subquery must return the inserted series"
+        values = {point["value"] for entry in series for point in entry.get("values") or []}
+        assert values == {42.0}, f"{leg}: {sorted(values)[:5]}"
+
+    # A plain follow-up query proves the process survived the subquery legs.
+    response = make_query_request(
+        signoz,
+        token,
+        start_ms,
+        end_ms,
+        [{"type": "promql", "spec": {"name": "A", "query": metric}}],
+    )
+    assert response.status_code == HTTPStatus.OK, response.text[:300]