wtf.spike

Spike

Run a time-boxed technical investigation.

This skill turns an unknown into a decision. It produces concrete findings and a recommendation. The team can then write specs with confidence rather than guess.

Process

0. GitHub CLI setup

Run steps 1–2 of ../references/gh-setup.md (install check and auth check). Stop if gh is not installed or not authenticated. Extensions are not required for this skill.

Skip this step if gh-setup was already confirmed this session.

1. Define the question

If the user described the investigation in their request, extract the core question from it. Otherwise call AskUserQuestion (per ../references/questioning-style.md):

• question: "What question should this spike answer?"
• header: "Spike question"
• options: specific questions inferred from any context provided (e.g. linked Epic, conversation)

The question must be specific and answerable. Scope it to a decision the team actually needs to make.

Call AskUserQuestion (per ../references/questioning-style.md):

• question: "How much time should this spike take?"
• header: "Time box"
• options:
  • 1 hour → quick feasibility check
  • Half day → moderate investigation
  • 1 day → deep dive with proof of concept

2. Identify the linked issue (optional)

Call AskUserQuestion (per ../references/questioning-style.md):

• question: "Is this spike linked to an existing issue?"
• header: "Linked issue"
• options:
  • Candidates from open Epics/Features — list per the List issues of a kind (several kinds) query in ../references/issue-classification.md. Use --label "epic,feature" in labels mode. Use --search 'type:"Epic" OR type:"Feature"' in types mode.
  • No linked issue — standalone investigation

If linked: fetch the issue to extract domain context, constraints, and success metrics that inform the investigation scope.

3. Research

Run all research in parallel using the Agent tool:

Codebase exploration:

• Search for existing implementations, prior attempts, or ADRs addressing the same question (domain nouns, patterns, imports)
• Load docs/steering/TECH.md per the best-effort consumer-side load in ../references/steering-doc-process.md for constraints that rule out certain approaches
• Identify integration points and dependencies the solution must respect

External research (if available):

• Use WebSearch/WebFetch for relevant documentation, benchmarks, or known trade-offs

Synthesise findings internally. Do not dump raw research at the user.

4. Derive 2–3 concrete approaches

For each approach:

• Name: short label (e.g. "Redis session store", "In-memory with TTL")
• Summary: one sentence describing what it involves
• Pros: 2–3 concrete advantages relevant to this codebase and constraints
• Cons: 2–3 concrete risks or costs
• Effort estimate: rough implementation cost (hours or days)
• Fit with TECH.md: does it align with the established stack and patterns?

5. Recommend

State a single recommendation:

"Recommend [Approach N] because [1–2 key reasons]. Main risk: [X], mitigated by [Y]."

If evidence is genuinely ambiguous or the spike revealed the question is harder than expected, say so clearly. Recommend a proof of concept or a follow-up spike with a narrower question.

6. Review with user

Show the full analysis (approaches + recommendation). Then call AskUserQuestion (per ../references/questioning-style.md):

• question: "Does this answer the question well enough to proceed?"
• header: "Spike review"
• options:
  • Yes — record the findings → write the spike doc
  • Need more depth on one approach → explore a specific area further
  • Question changed → the investigation revealed a different question

Apply any adjustments, then proceed.

7. Write the findings doc

Apply strict STE per ../references/ste-writing.md before writing any durable body.

Write to docs/spikes/<YYYY-MM-DD>-<slug>.md where <slug> is a 2–4 word kebab-case summary of the question (e.g. session-store-strategy).

Structure:

# Spike: <question>

**Date:** <YYYY-MM-DD>  
**Time box:** <duration>  
**Linked issue:** #<n> or —

## Question

<the specific question this spike answered>

## Approaches considered

### <Approach 1 name>
**Summary:** ...  
**Pros:** ...  
**Cons:** ...  
**Effort:** ...  

### <Approach 2 name>
...

## Recommendation

<recommendation text>

## Decision

<!-- Fill when the team decides -->
- [ ] Accepted — proceeding with [approach]
- [ ] Rejected — reason: ...
- [ ] Needs follow-up: ...

mkdir -p docs/spikes
git add docs/spikes/<filename>
git commit -m "docs(spike): <question summary>"

Print the file path.

8. Post to linked issue (if applicable)

If a linked issue exists, write this comment to a temp file with the Write tool. Then post it via the gh body helper (../references/gh-body-helper.md):

🔬 Spike concluded: → Recommendation: . Full findings: docs/spikes/.md

# $COMMENT is the temp file you wrote the comment above to.
python3 .wtf/gh-body.py comment <issue_number> --body-file "$COMMENT"

9. Offer next steps

Call AskUserQuestion (per ../references/questioning-style.md):

• question: "What's next?"
• header: "Next step"
• options:
  • Write an Epic from this → follow wtf.write-epic, seeding it with the spike's recommendation (default)
  • Write a Trace from this → follow wtf.write-trace with the spike recommendation as Technical Approach context
  • Stop here → exit. The team will decide separately.