| name | f-thread |
| description | Fusion/Comparison Thread for architecture decisions. Use when:
- User says "compare approaches", "which is better"
- User asks to "evaluate options", "architecture decision"
- User needs "technology selection", "trade-off analysis"
- Multiple valid approaches exist and a structured comparison is needed
|
| context | fork |
Fusion Thread: Architecture Decision Comparison
Structured approach to comparing multiple solutions using parallel evaluation, weighted scoring, and ADR output.
When to Use
- Choosing between technologies (e.g., Zustand vs Jotai vs Redux)
- Evaluating architecture patterns (e.g., monorepo vs polyrepo)
- Comparing implementation approaches for a feature
- Any decision with 2+ viable options and meaningful trade-offs
When NOT to Use
- One option is clearly superior (just recommend it)
- Trivial decisions (formatting, naming)
- Already decided by team convention
Workflow
1. Define Criteria
Establish evaluation criteria with weights (must sum to 100):
| Criterion | Weight | Description |
|------------------|--------|------------------------------------|
| Performance | 25 | Runtime speed, bundle size |
| DX | 20 | Developer experience, API quality |
| Maintainability | 20 | Long-term code health |
| Ecosystem | 15 | Community, plugins, docs |
| Migration Cost | 10 | Effort to adopt |
| Type Safety | 10 | TypeScript integration quality |
Preset Criteria Sets:
- Frontend: Performance (25), DX (20), Bundle Size (20), Accessibility (15), Ecosystem (10), Type Safety (10)
- Backend: Performance (25), Scalability (20), Maintainability (20), Security (15), Ops Complexity (10), Cost (10)
- Infrastructure: Reliability (25), Cost (20), Scalability (20), Ops Complexity (15), Vendor Lock-in (10), Migration (10)
2. Spawn Parallel Evaluators
Spawn one oracle agent per approach in a SINGLE message:
Task(oracle, "Evaluate [Approach A] against criteria: [criteria list with weights]. Score 1-10 per criterion. Include concrete examples, code samples, and evidence.")
Task(oracle, "Evaluate [Approach B] against criteria: [criteria list with weights]. Score 1-10 per criterion. Include concrete examples, code samples, and evidence.")
Task(oracle, "Evaluate [Approach C] against criteria: [criteria list with weights]. Score 1-10 per criterion. Include concrete examples, code samples, and evidence.")
Each evaluator must return:
- Score (1-10) per criterion with justification
- Concrete code example
- Key risks and mitigations
- Best-case and worst-case scenarios
3. Collect and Score
Build the comparison matrix from evaluator responses.
4. Synthesize Recommendation
Produce the final output in ADR format.
Output Format
Comparison Matrix
## Comparison: [Decision Title]
| Criterion (Weight) | Option A | Option B | Option C |
|-------------------------|----------|----------|----------|
| Performance (25) | 8 (200) | 6 (150) | 7 (175) |
| DX (20) | 9 (180) | 7 (140) | 6 (120) |
| Maintainability (20) | 7 (140) | 8 (160) | 5 (100) |
| Ecosystem (15) | 8 (120) | 9 (135) | 4 (60) |
| Migration Cost (10) | 6 (60) | 8 (80) | 3 (30) |
| Type Safety (10) | 9 (90) | 7 (70) | 8 (80) |
| **TOTAL** | **790** | **735** | **565** |
Score format: raw (weighted) where weighted = raw * weight
This extends the base ADR template from agents/planner.md with scoring matrix and detailed risk sections.
ADR Template
# ADR-NNN: [Decision Title]
## Status
Proposed
## Context
[Why this decision is needed. What problem we're solving.]
## Options Considered
1. **Option A** - [one-line summary]
2. **Option B** - [one-line summary]
3. **Option C** - [one-line summary]
## Decision
We will use **Option A** because [primary reasons].
## Scoring Summary
[Comparison matrix from above]
## Consequences
### Positive
- [benefit 1]
- [benefit 2]
### Negative
- [trade-off 1]
- [trade-off 2]
### Risks
- [risk 1] → Mitigation: [approach]
## References
- [relevant links, docs, benchmarks]
Examples
Example: State Management Selection
User: "Which state management should we use for this Next.js app?"
→ Define criteria (Frontend preset)
→ Task(oracle, "Evaluate Zustand against frontend criteria...")
+ Task(oracle, "Evaluate Jotai against frontend criteria...")
+ Task(oracle, "Evaluate Redux Toolkit against frontend criteria...")
→ Build comparison matrix
→ Output ADR recommendation
Example: Monorepo Tooling
User: "Compare Turborepo vs Nx for our monorepo"
→ Define criteria (Infrastructure preset)
→ Task(oracle, "Evaluate Turborepo...") + Task(oracle, "Evaluate Nx...")
→ Build comparison matrix
→ Output ADR recommendation
