operation %d: remove operation missing required id field

Error message

operation %d: remove operation missing required id field

What it means

applySubtaskOperations validates an LLM-generated subtask patch: a remove operation must name which subtask to delete via the ID field. When Op == SubtaskOpRemove and op.ID is nil, this validation error aborts the whole patch. It prevents an ambiguous delete from silently removing the wrong subtask.

Source

Thrown at backend/pkg/providers/subtask_patch.go:59

	// Build ID -> index map for position lookups
	idToIdx := buildIndexMap(result)

	// Track removals separately to avoid modifying the slice during iteration
	removed := make(map[int64]bool)

	// First pass: process removals and modifications in-place
	for i, op := range patch.Operations {
		opLogger := logger.WithFields(logrus.Fields{
			"operation_index": i,
			"operation":       op.Op,
			"id":              op.ID,
			"after_id":        op.AfterID,
		})

		switch op.Op {
		case tools.SubtaskOpRemove:
			if op.ID == nil {
				err := fmt.Errorf("operation %d: remove operation missing required id field", i)
				opLogger.Error(err.Error())
				return nil, err
			}
			if _, ok := idToIdx[*op.ID]; !ok {
				err := fmt.Errorf("operation %d: subtask with id %d not found for removal", i, *op.ID)
				opLogger.Error(err.Error())
				return nil, err
			}
			removed[*op.ID] = true
			opLogger.WithField("subtask_id", *op.ID).Debug("marked subtask for removal")

		case tools.SubtaskOpModify:
			if op.ID == nil {
				err := fmt.Errorf("operation %d: modify operation missing required id field", i)
				opLogger.Error(err.Error())
				return nil, err
			}
			if op.Title == "" && op.Description == "" {

View on GitHub (pinned to ea665308ba)

Solutions

Retry the refiner/assistant call — malformed LLM output is often transient.
Strengthen the tool/JSON schema so "id" is required for remove operations.
Check the prompt instructions explicitly require id on remove ops and include few-shot examples.
Log the raw patch and switch to a stronger model if failures are frequent.

Example fix

// before (LLM patch)
{"op":"remove","title":"Scan host"} // missing id
// after
{"op":"remove","id":3}

Defensive patterns

Strategy: validation

Validate before calling

for i, op := range ops {
    if op.Op == tools.SubtaskOpRemove && op.ID == nil {
        return fmt.Errorf("op %d: remove requires id", i)
    }
}

Type guard

func hasID(op tools.SubtaskOperation) bool { return op.ID != nil }

Try / catch

patched, err := applySubtaskOperations(ctx, logger, ops, subtasks)
if err != nil {
    log.Printf("invalid LLM patch, retrying refiner: %v", err)
    return retryRefiner(ctx, flow)
}

Prevention

Mark id as required in the JSON schema for remove operations.
Include few-shot examples of valid remove ops in the prompt.
Retry the refiner on validation failure; LLM output is nondeterministic.

When it happens

Trigger: The assistant/refiner LLM emits a JSON patch containing {"op":"remove"} without an "id" field; applySubtaskOperations (via patchAssistantFlowSubtasks or performSubtasksRefiner) rejects it during validation before applying.

Common situations: LLM hallucinating a malformed patch despite the tool schema; prompt template omitting that id is required for remove; weak model not respecting the JSON schema; client-built patches missing the field.

Understand the failure class

Background: Schema validation failed / invalid input schema: payload rejected because its shape doesn't match the expected schema — this error's family across 28 libraries.

Related errors

AI-assisted analysis of vxcontrol/pentagi@ea665308ba (2026-09-01). Data as JSON: /api/errors/f33dfd25f7fe2a4b. Report an issue: GitHub.