fix: resolve structured action context inputs

[Optic00]

Summary

• Centralize Action execution-context lookup across templates, ai_extract, and ai_agent.
• Resolve editor-provided item.* inputs, nested output paths, slices, trigger data, prior values, users, and SCM payloads.
• Preserve tolerant template placeholders while making missing configured AI inputs fail with a clear error.
• Serialize structured template and extraction values as JSON.

Behavior note

ai_agent previously skipped unresolved configured inputs and could run with a partial or empty prompt. It now fails the node before starting an LLM call. Present null values remain valid inputs.

Tests

• go test ./internal/services
• go test ./... after satisfying the required frontend/dist embed input

This PR includes focused public unit coverage. Test placement is also being discussed in #193; I am happy to adapt it to the maintainers preferred convention.

[stefan-ernst]

Finally had time to do a proper review with the core-tests repo being public. There are only 4 failures that should be resolved when rebasing this PR.

Only one finding remained:

1. [P1] Top-level actions cannot resolve several advertised item.* or any user.* inputs.

   executeAction
   (

   core/internal/services/action_service.go

   Lines 575 to 594 in 6078777

   	ctx := &models.ExecutionContext{
   	Action: action,
   	Event: event,
   	EffectiveActorID: effectiveActorID,
   	Variables: make(map[string]any),
   	StepResults: []models.StepResult{},
   	ChainID: chainID,
   	}
   	// Expose the effective actor to template expansion.
   	ctx.Variables["item_id"] = event.ItemID
   	ctx.Variables["workspace_id"] = event.WorkspaceID
   	ctx.Variables["actor_user_id"] = effectiveActorID
   	ctx.Variables["trigger_user_id"] = event.ActorUserID
   	for k, v := range event.OldValues {
   	ctx.Variables["old_"+k] = v
   	}
   	for k, v := range event.NewValues {
   	ctx.Variables["new_"+k] = v
   	}

   )
   creates an ExecutionContext without populating Item or Actor. The new resolveExecutionValue
   (

   core/internal/services/action_service.go

   Lines 1934 to 1961 in 6078777

   	case "item":
   	value, ok := currentItemFieldValueResolved(as.itemRepo, ctx, parts[1])
   	if !ok {
   	return nil, false
   	}
   	return nestedExecutionValue(value, parts[2:])
   	case "trigger":
   	if value, ok := ctx.Variables[parts[1]]; ok {
   	return nestedExecutionValue(value, parts[2:])
   	}
   	return nil, false
   	case "old":
   	if value, ok := ctx.Variables["old_"+parts[1]]; ok {
   	return nestedExecutionValue(value, parts[2:])
   	}
   	return nil, false
   	case "user":
   	if ctx.Actor != nil && len(parts) == 2 {
   	switch parts[1] {
   	case "name":
   	return ctx.Actor.FirstName + " " + ctx.Actor.LastName, true
   	case "email":
   	return ctx.Actor.Email, true
   	case "id":
   	return ctx.Actor.ID, true
   	}
   	}
   	return nil, false

   )
   requires those fields for:
   • item.id
   • item.status
   • item.priority
   • item.custom_field_*
   • every user.* input

   ctx.Item is populated only inside iterator execution; ctx.Actor is never populated. A production-shaped
   diagnostic using Event.ItemID=42 and EffectiveActorID=7 reproduced:

   item.id -> (, false)
   user.id -> (, false)

   This is user-visible because the editor explicitly suggests item.id, item.status, and item.priority, while
   buildAIAgentUserMessage
   (

   core/internal/services/action_service.go

   Lines 2287 to 2293 in 6078777

   	func (as *ActionService) buildAIAgentUserMessage(ctx *models.ExecutionContext, fields []string) (string, error) {
   	inputParts := make([]string, 0, len(fields))
   	for _, field := range fields {
   	value, ok := as.resolveExecutionValue(ctx, field)
   	if !ok {
   	return "", fmt.Errorf("input field %q not found in execution context", field)
   	}

   )
   now hard-fails when any configured input is missing. Valid editor-created agent actions therefore abort
   before invoking the LLM.

   The context should be hydrated from the event/effective actor, or the resolver should fall back through the
   repositories and event IDs.