fix: improve error messages for invalid payloads in Zeebe command binding

bindings/zeebe/command/activate_jobs.go

@@ -40,6 +40,45 @@ type activateJobsPayload struct {
 	RequestTimeout    *metadata.Duration `json:"requestTimeout,omitempty"`
 }
 
+// UnmarshalJSON implements json.Unmarshaler to provide field-specific error messages for
+// duration fields. Both timeout and requestTimeout must be Go duration strings (e.g. "30s", "5m", "1h30m").
+func (p *activateJobsPayload) UnmarshalJSON(data []byte) error {
+	var shadow struct {
+		JobType           string           `json:"jobType"`
+		MaxJobsToActivate *int32           `json:"maxJobsToActivate"`
+		Timeout           *json.RawMessage `json:"timeout,omitempty"`
+		WorkerName        string           `json:"workerName"`
+		FetchVariables    []string         `json:"fetchVariables"`
+		RequestTimeout    *json.RawMessage `json:"requestTimeout,omitempty"`
+	}
+	if err := json.Unmarshal(data, &shadow); err != nil {
+		return err
+	}
+
+	p.JobType = shadow.JobType
+	p.MaxJobsToActivate = shadow.MaxJobsToActivate
+	p.WorkerName = shadow.WorkerName
+	p.FetchVariables = shadow.FetchVariables
+
+	if shadow.Timeout != nil {
+		var d metadata.Duration
+		if err := d.UnmarshalJSON(*shadow.Timeout); err != nil {
+			return fmt.Errorf("invalid value for field 'timeout' (expected a Go duration string, e.g. \"30s\", \"5m\", \"1h30m\"): %w", err)
+		}
+		p.Timeout = &d
+	}
+
+	if shadow.RequestTimeout != nil {
+		var d metadata.Duration
+		if err := d.UnmarshalJSON(*shadow.RequestTimeout); err != nil {
+			return fmt.Errorf("invalid value for field 'requestTimeout' (expected a Go duration string, e.g. \"30s\", \"5m\", \"1h30m\"): %w", err)
+		}
+		p.RequestTimeout = &d
+	}
+
+	return nil
+}
+
 func (z *ZeebeCommand) activateJobs(ctx context.Context, req *bindings.InvokeRequest) (*bindings.InvokeResponse, error) {
 	var payload activateJobsPayload
 	err := json.Unmarshal(req.Data, &payload)

bindings/zeebe/command/activate_jobs_test.go

@@ -98,6 +98,75 @@ func (cmd3 *mockActivateJobsCommandStep3) Send(context.Context) ([]entities.Job,
 	return []entities.Job{}, nil
 }
 
+func TestActivateJobsPayloadUnmarshal(t *testing.T) {
+	t.Run("invalid timeout produces field-scoped error", func(t *testing.T) {
+		raw := `{"jobType":"worker","maxJobsToActivate":10,"timeout":"PT30S"}`
+		var p activateJobsPayload
+		err := p.UnmarshalJSON([]byte(raw))
+		require.Error(t, err)
+		assert.Contains(t, err.Error(), "timeout")
+		assert.Contains(t, err.Error(), "PT30S")
+		assert.Contains(t, err.Error(), "duration string")
+	})
+
+	t.Run("invalid requestTimeout produces field-scoped error", func(t *testing.T) {
+		raw := `{"jobType":"worker","maxJobsToActivate":10,"requestTimeout":"2minutes"}`
+		var p activateJobsPayload
+		err := p.UnmarshalJSON([]byte(raw))
+		require.Error(t, err)
+		assert.Contains(t, err.Error(), "requestTimeout")
+		assert.Contains(t, err.Error(), "2minutes")
+		assert.Contains(t, err.Error(), "duration string")
+	})
+
+	t.Run("valid Go duration strings succeed", func(t *testing.T) {
+		raw := `{"jobType":"worker","maxJobsToActivate":10,"timeout":"30s","requestTimeout":"5m"}`
+		var p activateJobsPayload
+		err := p.UnmarshalJSON([]byte(raw))
+		require.NoError(t, err)
+		require.NotNil(t, p.Timeout)
+		assert.Equal(t, 30*time.Second, p.Timeout.Duration)
+		require.NotNil(t, p.RequestTimeout)
+		assert.Equal(t, 5*time.Minute, p.RequestTimeout.Duration)
+	})
+
+	t.Run("numeric nanosecond timeout still parses correctly", func(t *testing.T) {
+		// Regression guard: numeric (nanosecond) values were accepted before and must remain valid.
+		raw := `{"jobType":"worker","maxJobsToActivate":10,"timeout":30000000000}`
+		var p activateJobsPayload
+		err := p.UnmarshalJSON([]byte(raw))
+		require.NoError(t, err)
+		require.NotNil(t, p.Timeout)
+		assert.Equal(t, 30*time.Second, p.Timeout.Duration)
+	})
+
+	t.Run("numeric nanosecond requestTimeout still parses correctly", func(t *testing.T) {
+		// Regression guard: numeric (nanosecond) values were accepted before and must remain valid.
+		raw := `{"jobType":"worker","maxJobsToActivate":10,"requestTimeout":300000000000}`
+		var p activateJobsPayload
+		err := p.UnmarshalJSON([]byte(raw))
+		require.NoError(t, err)
+		require.NotNil(t, p.RequestTimeout)
+		assert.Equal(t, 5*time.Minute, p.RequestTimeout.Duration)
+	})
+
+	t.Run("null timeout leaves pointer nil", func(t *testing.T) {
+		raw := `{"jobType":"worker","maxJobsToActivate":10,"timeout":null}`
+		var p activateJobsPayload
+		err := p.UnmarshalJSON([]byte(raw))
+		require.NoError(t, err)
+		assert.Nil(t, p.Timeout)
+	})
+
+	t.Run("null requestTimeout leaves pointer nil", func(t *testing.T) {
+		raw := `{"jobType":"worker","maxJobsToActivate":10,"requestTimeout":null}`
+		var p activateJobsPayload
+		err := p.UnmarshalJSON([]byte(raw))
+		require.NoError(t, err)
+		assert.Nil(t, p.RequestTimeout)
+	})
+}
+
 func TestActivateJobs(t *testing.T) {
 	testLogger := logger.NewLogger("test")
 

bindings/zeebe/command/create_instance.go

@@ -41,6 +41,41 @@ type createInstancePayload struct {
 	RequestTimeout       *metadata.Duration `json:"requestTimeout,omitempty"`
 }
 
+// UnmarshalJSON implements json.Unmarshaler to provide a field-specific error message for
+// the requestTimeout duration field. The requestTimeout field must be a Go duration string
+// (e.g. "30s", "5m", "1h30m").
+func (p *createInstancePayload) UnmarshalJSON(data []byte) error {
+	var shadow struct {
+		BpmnProcessID        string           `json:"bpmnProcessId"`
+		ProcessDefinitionKey *int64           `json:"processDefinitionKey"`
+		Version              *int32           `json:"version"`
+		Variables            interface{}      `json:"variables"`
+		WithResult           bool             `json:"withResult"`
+		FetchVariables       []string         `json:"fetchVariables"`
+		RequestTimeout       *json.RawMessage `json:"requestTimeout,omitempty"`
+	}
+	if err := json.Unmarshal(data, &shadow); err != nil {
+		return err
+	}
+
+	p.BpmnProcessID = shadow.BpmnProcessID
+	p.ProcessDefinitionKey = shadow.ProcessDefinitionKey
+	p.Version = shadow.Version
+	p.Variables = shadow.Variables
+	p.WithResult = shadow.WithResult
+	p.FetchVariables = shadow.FetchVariables
+
+	if shadow.RequestTimeout != nil {
+		var d metadata.Duration
+		if err := d.UnmarshalJSON(*shadow.RequestTimeout); err != nil {
+			return fmt.Errorf("invalid value for field 'requestTimeout' (expected a Go duration string, e.g. \"30s\", \"5m\", \"1h30m\"): %w", err)
+		}
+		p.RequestTimeout = &d
+	}
+
+	return nil
+}
+
 func (z *ZeebeCommand) createInstance(ctx context.Context, req *bindings.InvokeRequest) (*bindings.InvokeResponse, error) {
 	var payload createInstancePayload
 	err := json.Unmarshal(req.Data, &payload)

bindings/zeebe/command/create_instance_test.go

@@ -17,6 +17,7 @@ import (
 	"context"
 	"encoding/json"
 	"testing"
+	"time"
 
 	"github.com/camunda/zeebe/clients/go/v8/pkg/commands"
 	"github.com/camunda/zeebe/clients/go/v8/pkg/pb"
@@ -98,6 +99,45 @@ func (cmd3 *mockCreateInstanceCommandStep3) Send(context.Context) (*pb.CreatePro
 	return &pb.CreateProcessInstanceResponse{}, nil
 }
 
+func TestCreateInstancePayloadUnmarshal(t *testing.T) {
+	t.Run("invalid requestTimeout produces field-scoped error", func(t *testing.T) {
+		raw := `{"bpmnProcessId":"order-process","requestTimeout":"PT5M"}`
+		var p createInstancePayload
+		err := p.UnmarshalJSON([]byte(raw))
+		require.Error(t, err)
+		assert.Contains(t, err.Error(), "requestTimeout")
+		assert.Contains(t, err.Error(), "PT5M")
+		assert.Contains(t, err.Error(), "duration string")
+	})
+
+	t.Run("valid Go duration string succeeds", func(t *testing.T) {
+		raw := `{"bpmnProcessId":"order-process","requestTimeout":"5m"}`
+		var p createInstancePayload
+		err := p.UnmarshalJSON([]byte(raw))
+		require.NoError(t, err)
+		require.NotNil(t, p.RequestTimeout)
+		assert.Equal(t, 5*time.Minute, p.RequestTimeout.Duration)
+	})
+
+	t.Run("numeric nanosecond requestTimeout still parses correctly", func(t *testing.T) {
+		// Regression guard: numeric (nanosecond) values were accepted before and must remain valid.
+		raw := `{"bpmnProcessId":"order-process","requestTimeout":300000000000}`
+		var p createInstancePayload
+		err := p.UnmarshalJSON([]byte(raw))
+		require.NoError(t, err)
+		require.NotNil(t, p.RequestTimeout)
+		assert.Equal(t, 5*time.Minute, p.RequestTimeout.Duration)
+	})
+
+	t.Run("null requestTimeout leaves pointer nil", func(t *testing.T) {
+		raw := `{"bpmnProcessId":"order-process","requestTimeout":null}`
+		var p createInstancePayload
+		err := p.UnmarshalJSON([]byte(raw))
+		require.NoError(t, err)
+		assert.Nil(t, p.RequestTimeout)
+	})
+}
+
 func TestCreateInstance(t *testing.T) {
 	testLogger := logger.NewLogger("test")
 

bindings/zeebe/command/fail_job.go

@@ -36,6 +36,37 @@ type failJobPayload struct {
 	Variables    interface{}        `json:"variables"`
 }
 
+// UnmarshalJSON implements json.Unmarshaler to provide a field-specific error message for
+// the retryBackOff duration field. The retryBackOff field must be a Go duration string
+// (e.g. "30s", "5m", "1h30m").
+func (p *failJobPayload) UnmarshalJSON(data []byte) error {
+	var shadow struct {
+		JobKey       *int64           `json:"jobKey"`
+		Retries      *int32           `json:"retries"`
+		ErrorMessage string           `json:"errorMessage"`
+		RetryBackOff *json.RawMessage `json:"retryBackOff,omitempty"`
+		Variables    interface{}      `json:"variables"`
+	}
+	if err := json.Unmarshal(data, &shadow); err != nil {
+		return err
+	}
+
+	p.JobKey = shadow.JobKey
+	p.Retries = shadow.Retries
+	p.ErrorMessage = shadow.ErrorMessage
+	p.Variables = shadow.Variables
+
+	if shadow.RetryBackOff != nil {
+		var d metadata.Duration
+		if err := d.UnmarshalJSON(*shadow.RetryBackOff); err != nil {
+			return fmt.Errorf("invalid value for field 'retryBackOff' (expected a Go duration string, e.g. \"30s\", \"5m\", \"1h30m\"): %w", err)
+		}
+		p.RetryBackOff = &d
+	}
+
+	return nil
+}
+
 func (z *ZeebeCommand) failJob(ctx context.Context, req *bindings.InvokeRequest) (*bindings.InvokeResponse, error) {
 	var payload failJobPayload
 	err := json.Unmarshal(req.Data, &payload)

bindings/zeebe/command/fail_job_test.go

@@ -17,6 +17,7 @@ import (
 	"context"
 	"encoding/json"
 	"testing"
+	"time"
 
 	"github.com/camunda/zeebe/clients/go/v8/pkg/commands"
 	"github.com/camunda/zeebe/clients/go/v8/pkg/pb"
@@ -82,6 +83,45 @@ func (cmd3 *mockFailJobCommandStep3) Send(context.Context) (*pb.FailJobResponse,
 	return &pb.FailJobResponse{}, nil
 }
 
+func TestFailJobPayloadUnmarshal(t *testing.T) {
+	t.Run("invalid retryBackOff produces field-scoped error", func(t *testing.T) {
+		raw := `{"jobKey":1,"retries":3,"retryBackOff":"PT10S"}`
+		var p failJobPayload
+		err := p.UnmarshalJSON([]byte(raw))
+		require.Error(t, err)
+		assert.Contains(t, err.Error(), "retryBackOff")
+		assert.Contains(t, err.Error(), "PT10S")
+		assert.Contains(t, err.Error(), "duration string")
+	})
+
+	t.Run("valid Go duration string succeeds", func(t *testing.T) {
+		raw := `{"jobKey":1,"retries":3,"retryBackOff":"10s"}`
+		var p failJobPayload
+		err := p.UnmarshalJSON([]byte(raw))
+		require.NoError(t, err)
+		require.NotNil(t, p.RetryBackOff)
+		assert.Equal(t, 10*time.Second, p.RetryBackOff.Duration)
+	})
+
+	t.Run("numeric nanosecond retryBackOff still parses correctly", func(t *testing.T) {
+		// Regression guard: numeric (nanosecond) values were accepted before and must remain valid.
+		raw := `{"jobKey":1,"retries":3,"retryBackOff":30000000000}`
+		var p failJobPayload
+		err := p.UnmarshalJSON([]byte(raw))
+		require.NoError(t, err)
+		require.NotNil(t, p.RetryBackOff)
+		assert.Equal(t, 30*time.Second, p.RetryBackOff.Duration)
+	})
+
+	t.Run("null retryBackOff leaves pointer nil", func(t *testing.T) {
+		raw := `{"jobKey":1,"retries":3,"retryBackOff":null}`
+		var p failJobPayload
+		err := p.UnmarshalJSON([]byte(raw))
+		require.NoError(t, err)
+		assert.Nil(t, p.RetryBackOff)
+	})
+}
+
 func TestFailJob(t *testing.T) {
 	testLogger := logger.NewLogger("test")
 

bindings/zeebe/command/publish_message.go

@@ -34,6 +34,37 @@ type publishMessagePayload struct {
 	Variables      interface{}        `json:"variables"`
 }
 
+// UnmarshalJSON implements json.Unmarshaler to provide field-specific error messages for
+// duration fields. The timeToLive field must be a Go duration string (e.g. "30s", "5m", "1h30m").
+func (p *publishMessagePayload) UnmarshalJSON(data []byte) error {
+	// Use a shadow struct with raw JSON for duration fields so we can provide better errors.
+	var shadow struct {
+		MessageName    string           `json:"messageName"`
+		CorrelationKey string           `json:"correlationKey"`
+		MessageID      string           `json:"messageId"`
+		TimeToLive     *json.RawMessage `json:"timeToLive,omitempty"`
+		Variables      interface{}      `json:"variables"`
+	}
+	if err := json.Unmarshal(data, &shadow); err != nil {
+		return err
+	}
+
+	p.MessageName = shadow.MessageName
+	p.CorrelationKey = shadow.CorrelationKey
+	p.MessageID = shadow.MessageID
+	p.Variables = shadow.Variables
+
+	if shadow.TimeToLive != nil {
+		var d metadata.Duration
+		if err := d.UnmarshalJSON(*shadow.TimeToLive); err != nil {
+			return fmt.Errorf("invalid value for field 'timeToLive' (expected a Go duration string, e.g. \"30s\", \"5m\", \"1h30m\"): %w", err)
+		}
+		p.TimeToLive = &d
+	}
+
+	return nil
+}
+
 func (z *ZeebeCommand) publishMessage(ctx context.Context, req *bindings.InvokeRequest) (*bindings.InvokeResponse, error) {
 	var payload publishMessagePayload
 	err := json.Unmarshal(req.Data, &payload)