Project 10: Visual Rule Builder (No-Code DSL)

Build a visual authoring interface that creates valid CPQ rules and round-trips perfectly with text DSL representations.

Quick Reference

Attribute Value
Difficulty Level 3 (Advanced)
Time Estimate 4-5 weeks
Main Programming Language TypeScript/React (Alternatives: Vue, Svelte)
Coolness Level Level 4
Business Potential 5. Industry Disruptor
Prerequisites Projects 8-9, UI architecture, AST models
Key Topics Visual AST editing, round-trip fidelity, publish governance

1. Learning Objectives

  1. Represent DSL rules as visual blocks/nodes with strict constraints.
  2. Maintain a shared canonical IR between visual and text editors.
  3. Provide real-time validation and simulation feedback.
  4. Implement role-based publication gates for rule changes.

2. All Theory Needed (Per-Concept Breakdown)

Concept A: Canonical IR for Visual/Text Parity

Fundamentals Visual and text authoring must converge to one canonical representation, or drift becomes inevitable.

Deep Dive into the concept Use IR as single source-of-truth. Visual blocks map to IR nodes; text DSL parser maps to same IR nodes. Validate both through shared semantics. Round-trip tests are mandatory.

How this fit on projects Primary here; consumes outputs of P08-product-rules-dsl.md and P09-pricing-rules-dsl.md.

Definitions & key terms

  • Canonical IR
  • Round-trip fidelity
  • Publish gate

Mental model diagram

Visual Editor -> IR <- DSL Text Editor
                   |
                   v
            Validator + Simulator -> Publish Pipeline

How it works

  1. User edits rule visually or textually.
  2. System updates canonical IR.
  3. Shared validator checks correctness.
  4. Simulation results gate publication.

Minimal concrete example

Visual blocks: IF segment=Enterprise THEN discount=min(12%,guard)
serialize -> IR -> DSL text -> IR (same structure)

Common misconceptions

  • “Visual builder can own separate JSON schema.” This creates long-term divergence.

Check-your-understanding questions

  1. Why use shared IR for both editors?
  2. Why require simulation before publish?

Check-your-understanding answers

  1. To guarantee semantic parity and round-trip stability.
  2. To catch policy regressions before activation.

Real-world applications No-code policy authoring, operations automation tools.

Where you’ll apply it This project and operationally with Projects 8-9.

References

  • Blockly patterns.
  • DSL parser references.

Key insights No-code only scales when technical guarantees are stronger, not weaker.

Summary Shared IR + validation + governance converts no-code from risk to leverage.

Homework/Exercises to practice the concept Create one complex rule in visual form and prove text round-trip equivalence.

Solutions to the homework/exercises Use canonical serializer and compare normalized IR hashes.

3. Project Specification

3.1 What You Will Build

A web-based visual rule editor with drag/drop blocks, live validation, DSL preview, and governed publish workflow.

3.2 Functional Requirements

  1. Create/edit rules visually.
  2. Import/export DSL text with round-trip parity.
  3. Run simulations before publish.
  4. Enforce role-based publish approvals.

3.3 Non-Functional Requirements

  • Performance: editing operations feel real-time (<100ms feedback).
  • Reliability: no rule corruption during format conversion.
  • Usability: non-developers can author valid rules with minimal training.

3.4 Example Usage / Output

User creates pricing rule via blocks -> validation passes -> simulation 42/42 pass -> publish draft

3.5 Data Formats / Schemas / Protocols

  • VisualNode(id, type, children, metadata)
  • CanonicalIR(ruleSetId, nodes, version)
  • PublishRecord(id, actor, simulationReportId, status)

3.6 Edge Cases

  • Unsupported legacy DSL syntax.
  • Partial visual graph with missing required node.
  • Concurrent edits from two users.

3.7 Real World Outcome

3.7.1 How to Run (Copy/Paste)

$ npm run dev
# open http://localhost:3000/rules/studio

3.7.2 Golden Path Demo (Deterministic)

Same rule imported from DSL and visual editor yields same normalized IR hash.

3.7.4 If Web App

  • URL: /rules/studio
  • Panels: block palette, rule canvas, validation panel, DSL preview
  • Buttons: Run Simulation, Save Draft, Request Publish, Activate

ASCII wireframe:

+--------------------------------------------------------------------------------+
| Rule Studio                                                                    |
|--------------------------------------------------------------------------------|
| Palette              | Canvas                          | Validation             |
| [Condition]          | IF segment == Enterprise        | ✓ syntax               |
| [Math]               | THEN discount=min(12%,guard)    | ✓ semantics            |
| [Action]             |                                  | ✓ simulation (42/42)   |
|--------------------------------------------------------------------------------|
| [Save Draft] [Run Simulation] [Request Publish] [Activate]                     |
+--------------------------------------------------------------------------------+

4. Solution Architecture

4.1 High-Level Design

UI Editor -> Canonical IR Service -> Validator/Simulator -> Publish Workflow

4.2 Key Components

| Component | Responsibility | Key Decisions | |———–|—————-|—————| | Visual Editor | block authoring UX | constrained node combinations | | IR Service | canonical model management | one model for text+visual | | Publish Workflow | governance controls | role checks + simulation gate |

4.4 Data Structures (No Full Code)

EditorSession { userId, ruleSetId, draftVersion, lockToken }
RoundTripCheck { irHashBefore, irHashAfter, equal }

4.4 Algorithm Overview

  1. Edit block graph.
  2. Convert to canonical IR.
  3. Validate and simulate.
  4. Publish through approval path.

5. Implementation Guide

5.1 Development Environment Setup

$ npm install
$ npm run dev
$ npm run test

5.2 Project Structure

rule-studio/
  src/
    editor/
    ir/
    validation/
    publish/

5.3 The Core Question You’re Answering

“Can no-code rule authoring remain safe, explainable, and enterprise-governed at scale?”

5.4 Concepts You Must Understand First

  • AST/IR representation
  • round-trip testing
  • role-based publication controls

5.5 Questions to Guide Your Design

  • How do you prevent invalid block combinations?
  • How do you prove text/visual parity over time?

5.6 Thinking Exercise

Design a review workflow for high-impact rule changes with rollback plan.

5.7 The Interview Questions They’ll Ask

  1. How do you ensure visual and text rule equivalence?
  2. How do you govern no-code publication risk?
  3. How do you handle collaborative editing safely?

5.8 Hints in Layers

  • Hint 1: IR first, UI second.
  • Hint 2: live validation on every edit.
  • Hint 3: publish only after simulation + approval.

5.9 Books That Will Help

| Topic | Book | Chapter | |——-|——|———| | Architecture constraints | “Fundamentals of Software Architecture” | Ch. 7-11 | | Boundaries and policy flow | “Clean Architecture” | Ch. 21-23 |

5.10 Implementation Phases

  • Phase 1: block editor + IR conversion.
  • Phase 2: validation/simulation integration.
  • Phase 3: governed publish workflow.

5.11 Key Implementation Decisions

| Decision | Options | Recommendation | Rationale | |———-|———|—————-|———–| | Canonical model | dual model, shared IR | shared IR | parity and maintainability | | Publish gate | optional, mandatory | mandatory | safety and audit |

6. Testing Strategy

6.1 Test Categories

| Category | Purpose | Examples | |———-|———|———-| | Unit | node conversion | visual->IR | | Integration | editor+validator | live errors | | Regression | round-trip parity | DSL<->visual hash checks |

6.2 Critical Test Cases

  1. Complex rule round-trip equivalence.
  2. Invalid node combination blocked in UI.
  3. Publish blocked when simulation fails.

6.3 Test Data

rule_graph_samples.json, dsl_roundtrip_cases.dsl.

7. Common Pitfalls & Debugging

7.1 Frequent Mistakes

| Pitfall | Symptom | Solution | |———|———|———-| | dual source model | drift between editors | enforce shared IR | | weak publish checks | bad rules activated | mandatory simulation gate |

7.2 Debugging Strategies

  • Compare IR snapshots before/after conversions.
  • Replay publish pipeline with diagnostic traces.

7.3 Performance Traps

Avoid re-rendering full graph for tiny node edits.

8. Extensions & Challenges

8.1 Beginner Extensions

  • Add keyboard shortcuts.
  • Add reusable rule templates.

8.2 Intermediate Extensions

  • Collaborative comments on rule drafts.
  • Rule impact preview panel.

8.3 Advanced Extensions

  • Multi-user live collaboration with conflict resolution.
  • Policy experimentation with guarded rollout cohorts.

9. Real-World Connections

9.1 Industry Applications

  • No-code policy management platforms.
  • Business-authorable automation tools.

9.3 Interview Relevance

Demonstrates advanced product/platform engineering at business-logic boundaries.

10. Resources

10.1 Essential Reading

  • Visual programming system design references.
  • DSL tooling references.

10.2 Video Resources

  • No-code platform architecture talks.

10.3 Tools & Documentation

  • Blockly docs, UI performance profiling docs.

11. Self-Assessment Checklist

  • I can prove round-trip fidelity between visual and text forms.
  • Invalid rule structures are blocked early.
  • Publication requires simulation and approval evidence.

12. Submission / Completion Criteria

Minimum Viable Completion:

  • Visual editor + IR conversion works.

Full Completion:

  • Live validation and simulation integrated.
  • Publish governance implemented.

Excellence (Going Above & Beyond):

  • Collaborative editing and advanced impact analysis.