fix(nightscout): handle float date values via custom UnmarshalJSON

Some Nightscout API providers (e.g. T1Pal) return the date field as a
float (e.g. 1770512410938.386). Go's json.Unmarshal cannot decode a
float into an int64 field, causing the segment to silently fail.

Add a custom UnmarshalJSON that accepts both integer and floating-point
JSON numbers, truncating to int64. This preserves the existing Date
int64 type and is fully backward compatible.

Fixes #7284

Author: shanselman

src/segments/nightscout.go

@@ -3,6 +3,7 @@ package segments
 import (
 	"encoding/json"
 	"errors"
+	"fmt"
 	http2 "net/http"
 	"time"
 
@@ -46,6 +47,38 @@ type NightscoutData struct {
 	Mills      int64     `json:"mills"`
 }
 
+// UnmarshalJSON handles both integer and floating-point JSON numbers for the date field.
+// Some Nightscout API providers (e.g. T1Pal) return the date as a float.
+func (n *NightscoutData) UnmarshalJSON(data []byte) error {
+	type Alias NightscoutData
+	aux := &struct {
+		*Alias
+		Date json.Number `json:"date"`
+	}{
+		Alias: (*Alias)(n),
+	}
+
+	if err := json.Unmarshal(data, aux); err != nil {
+		return err
+	}
+
+	if aux.Date == "" {
+		return nil
+	}
+
+	if i, err := aux.Date.Int64(); err == nil {
+		n.Date = i
+		return nil
+	}
+
+	if f, err := aux.Date.Float64(); err == nil {
+		n.Date = int64(f)
+		return nil
+	}
+
+	return fmt.Errorf("date field must be a valid number, got: %s", aux.Date)
+}
+
 func (ns *Nightscout) Template() string {
 	return " {{ .Sgv }} "
 }

src/segments/nightscout_test.go

@@ -1,6 +1,7 @@
 package segments
 
 import (
+	"encoding/json"
 	"errors"
 	"testing"
 
@@ -82,6 +83,14 @@ func TestNSSegment(t *testing.T) {
 			ExpectedString:  "\ue2a1 50↓↓",
 			ExpectedEnabled: true,
 		},
+		{
+			Case: "Float date value",
+			JSONResponse: `
+			[{"_id":"619d6fa819696e8ded5b2206","sgv":124,"date":1770512410938.386,"dateString":"2026-02-08T01:00:10.000Z","trend":4,"direction":"Flat","device":"share2","type":"sgv","utcOffset":0,"sysTime":"2026-02-08T01:00:10.000Z","mills":1770512410000}]`, //nolint:lll
+			Template:        "\ue2a1 {{.Sgv}}{{.TrendIcon}}",
+			ExpectedString:  "\ue2a1 124→",
+			ExpectedEnabled: true,
+		},
 		{
 			Case:            "Error in retrieving data",
 			JSONResponse:    "nonsense",
@@ -135,3 +144,50 @@ func TestNSSegment(t *testing.T) {
 		assert.Equal(t, tc.ExpectedString, renderTemplate(env, tc.Template, ns), tc.Case)
 	}
 }
+
+func TestNightscoutDataUnmarshalJSON(t *testing.T) {
+	cases := []struct {
+		Case         string
+		JSONInput    string
+		ExpectedDate int64
+		ExpectError  bool
+	}{
+		{
+			Case:         "Integer date value",
+			JSONInput:    `{"date": 1637707537000}`,
+			ExpectedDate: 1637707537000,
+		},
+		{
+			Case:         "Floating-point date value",
+			JSONInput:    `{"date": 1637707537000.5}`,
+			ExpectedDate: 1637707537000,
+		},
+		{
+			Case:         "Floating-point date with larger decimal",
+			JSONInput:    `{"date": 1637707537123.789}`,
+			ExpectedDate: 1637707537123,
+		},
+		{
+			Case:        "Invalid date value",
+			JSONInput:   `{"date": "not-a-number"}`,
+			ExpectError: true,
+		},
+		{
+			Case:      "Missing date field",
+			JSONInput: `{"sgv": 150}`,
+		},
+	}
+
+	for _, tc := range cases {
+		var data NightscoutData
+		err := json.Unmarshal([]byte(tc.JSONInput), &data)
+
+		if tc.ExpectError {
+			assert.Error(t, err, tc.Case)
+			continue
+		}
+
+		assert.NoError(t, err, tc.Case)
+		assert.Equal(t, tc.ExpectedDate, data.Date, tc.Case)
+	}
+}