Spike: Define IntelliSense user experience

[lornakelly]

Description

Define the authoring-assistance UX for the text pane - what IntelliSense should feel like - independent of which editor/library implements it. The output is demo/presentation to the team to initiate discussions and decide on features.

Keep in mind the personas and define the experience for both.

1. The newcomer - someone who has no experience writing workflows
2. The fixer - faster authoring and debugging.

Motivation

Authoring assistance is crucial for Milestone 1. A focused, research-led UX spike de-risks the headline feature.

Proposed Implementation

• Research: schema-driven YAML/JSON authoring in mature editors and evaluate which patterns are worth copying vs avoiding.
• Define the experience: trigger behaviour (as-you-type / ctrl+space / after : etc),
• Accessibility: keyboard navigation, focus handling, screen-reader announcements.
• Prioritise: must-have vs nice-to-have for Milestone 1

Definition of Done

• Implementation: Fully implemented according to the Serverless Workflow spec.
• Unit Tests: Comprehensive unit tests are included and passing.
• Integration Tests: Verified within the monorepo and target environments (Web/VS Code).
• Documentation: Updated README.md, ADRs, or official docs.
• Performance: No significant regression in editor responsiveness.
• Accessibility: UI changes comply with accessibility standards.