sd0xdev/feasibility-study

Feasibility Study Skill

Supplementary Agent

For each solution option, dispatch background exploration:

Agent({ description: "Explore feasibility of solution option", subagent_type: "feasibility-analyst", prompt: Research the feasibility of: <solution description> Evaluate technical feasibility, effort, risk, extensibility, and maintenance cost. })

Trigger

• Keywords: feasibility, is this possible, can we, should we, explore options, before tech spec

When NOT to Use

• Already have a tech spec (use /deep-analyze)
• Need implementation, not analysis (use /codex-implement)
• Quick question (use /codex-explain or /codex-architect)

Workflow

Decompose → Constraints → Code research → Solutions → Codex discussion → Decision → Report

Phase 1: Requirement Decomposition

Input source priority:

1. If canonical_docs.requirements is non-null → consume as authoritative requirement source, validate via 5-Why
2. Otherwise → extract requirements from user input via 5-Why analysis

Use "5 Why" to uncover essence:

1. Surface requirement (what user asks for)
2. Underlying problem (why they need it)
3. Success criteria (quantifiable acceptance)

Phase 2: Constraint Analysis

Inventory constraints by type (Technical, Business, Resource, Compatibility) with flexibility rating.

Phase 3: Code Research

Research existing codebase:

• Related modules and reusable logic
• Existing design patterns
• Tech debt to work around

Phase 4: Solution Exploration

Brainstorm 2-3+ solutions, each with:

1. Core idea (one sentence)
2. Implementation path
3. Quantified feasibility (see references/analysis-phases.md)
4. Cost and trade-offs

Phase 5: In-Depth Codex Discussion

⚠️ Core step — not optional (unless --no-codex) ⚠️

See references/codex-discussion-guide.md for full rules and examples.

| Tool | Purpose | When | |------|---------|------| | /codex-brainstorm | Enumerate all options | At start | | /codex-architect | Evaluate design | After proposal forms | | mcp__codex__codex-reply | Ask details | Anytime |

Phase 6: Comparative Decision

Side-by-side comparison → recommendation + backup + open questions.

Evaluation Dimensions

| Dimension | Green | Yellow | Red | | --------------------- | ----- | ------ | --- | | Technical Feasibility | Has existing patterns | Needs adaptation | Major innovation | | Effort | < 3 person-days | 3-10 person-days | > 10 person-days | | Risk | Small scope | Some uncertainty | Many unknowns | | Extensibility | Easy to extend | Needs refactoring | Hard to extend | | Maintenance Cost | Clean, easy | Some complexity | Complex |

Output

## Feasibility Study: <title>
### Quantitative Comparison
| Criterion | Option A | Option B | Option C |
|-----------|----------|----------|----------|

### Recommendation
<selected option with rationale>

Verification

• [ ] 5 Why decomposition completed
• [ ] Constraints inventoried with flexibility
• [ ] Existing code researched (grep/read)
• [ ] 2-3+ solutions explored with quantified assessment
• [ ] Codex discussion documented (unless --no-codex)
• [ ] Comparison table + recommendation + open questions

References

• Analysis phases: references/analysis-phases.md
• Codex discussion: references/codex-discussion-guide.md
• Output template: references/output-template.md

Relationship with Other Commands

/feasibility-study → /tech-spec → /deep-analyze → /codex-implement

Examples

Input: /feasibility-study "Add user quota management"
Action: 5 Why → constraints → code research → 3 solutions → Codex discussion → recommendation

Input: /feasibility-study "Optimize cache" --context src/service/cache.ts
Action: Read cache code → constraints → solutions → Codex brainstorm → comparison → report