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assumption-challenger

@alirezarezvani/claude-cto-team
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Identify and challenge implicit assumptions in plans, proposals, and technical decisions. Use when strategic-cto-mentor needs to surface hidden assumptions and wishful thinking before they become costly mistakes.

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SKILL.md

name assumption-challenger
description Identify and challenge implicit assumptions in plans, proposals, and technical decisions. Use when strategic-cto-mentor needs to surface hidden assumptions and wishful thinking before they become costly mistakes.

Assumption Challenger

Systematically identifies and stress-tests assumptions that are treated as facts but may not be validated.

When to Use

  • Validating roadmaps and project plans
  • Reviewing architecture proposals
  • Assessing build vs buy decisions
  • Evaluating timelines and budgets
  • Challenging strategic initiatives

Why Assumptions Matter

Most project failures trace back to invalid assumptions:

  • Timeline assumptions: "We can ship in 6 weeks" (based on nothing)
  • Resource assumptions: "We'll hire 3 engineers" (in a tight market)
  • Technical assumptions: "The API can handle 10K requests/sec" (never tested)
  • Business assumptions: "Users will adopt this feature" (never validated)

The cost of invalid assumptions compounds over time. A bad assumption in week 1 can waste months of work.


Assumption Categories

1. Timeline Assumptions

Assumptions about how long things will take.

Common patterns:

  • "This should only take 2 weeks"
  • "We'll have the integration done by launch"
  • "The team can absorb this additional scope"

Challenge questions:

  • What's this estimate based on? Past experience or hope?
  • What similar work have we done? How long did it actually take?
  • What's not included in this estimate? (Testing, documentation, deployment)
  • What happens if this takes 2x longer?

2. Resource Assumptions

Assumptions about team capacity and availability.

Common patterns:

  • "We'll hire 2 senior engineers by Q2"
  • "The DevOps team can support this"
  • "Sarah can lead this while maintaining her other work"

Challenge questions:

  • What's the hiring timeline? What if we can't find the right people?
  • What's the team's current utilization? Where does time come from?
  • Who's the backup if the key person is unavailable?
  • What happens if the team is 50% of expected capacity?

3. Technical Assumptions

Assumptions about system capabilities and constraints.

Common patterns:

  • "The database can handle the load"
  • "We can integrate with their API easily"
  • "Our architecture supports this use case"

Challenge questions:

  • Has this been tested at the required scale?
  • What are the documented limits? What happens at those limits?
  • What's the failure mode? How do we recover?
  • Have we talked to the API provider about our usage patterns?

4. Business Assumptions

Assumptions about market, users, and business outcomes.

Common patterns:

  • "Users want this feature"
  • "This will reduce churn by 20%"
  • "The market will wait for our solution"

Challenge questions:

  • What evidence supports this? User research? Data?
  • What if users don't adopt this? What's the fallback?
  • What are competitors doing in this space?
  • How will we know if this assumption is wrong?

5. External Assumptions

Assumptions about factors outside your control.

Common patterns:

  • "The vendor will have the feature ready"
  • "Regulations won't change"
  • "The market will remain stable"

Challenge questions:

  • What's our contingency if this doesn't happen?
  • What's the vendor's track record on commitments?
  • What early warning signs would indicate this is wrong?
  • What's the cost of being wrong?

Assumption Identification Process

Step 1: Surface Assumptions

Read the proposal and identify statements that are treated as facts but aren't validated:

Flag statements containing:

  • "We will..." (without evidence)
  • "We can..." (without proof)
  • "Users want..." (without data)
  • "It should..." (without testing)
  • "We expect..." (without basis)
  • "We assume..." (at least they're honest)

Step 2: Categorize Assumptions

For each assumption, categorize:

Category Risk if Wrong Validation Difficulty
Timeline Project delay Medium (compare to past)
Resource Execution failure Medium (check market)
Technical System failure High (requires testing)
Business Wasted investment High (requires market validation)
External Plans disrupted Variable

Step 3: Assess Each Assumption

For each significant assumption:

### Assumption: [Statement]

**Category**: [Type]
**Stated or Implicit**: [Was it stated or hidden?]

**Evidence Supporting**:
- [Evidence 1]
- [Evidence 2]

**Evidence Against**:
- [Counter-evidence 1]
- [Counter-evidence 2]

**Risk if Wrong**:
- [Impact on timeline]
- [Impact on cost]
- [Impact on success]

**Validation Method**:
- [How to test this assumption]
- [Cost/time to validate]

**Verdict**:
[ ] Valid - Evidence supports
[ ] Questionable - Needs validation
[ ] Invalid - Evidence contradicts
[ ] Unknown - Cannot assess

Step 4: Prioritize Challenges

Focus on assumptions that are:

  1. High impact - Project fails if wrong
  2. Low evidence - Based on hope, not data
  3. Testable - Can be validated before commitment

Challenge Patterns

The Reality Check

Compare assumption to external data.

Template:

"You assume [X]. Industry data shows [Y]. What makes you different?"

Example:

"You assume you can hire 3 senior engineers in 2 months. The average time-to-hire for senior engineers in your market is 4-6 months. What's your strategy to beat that?"

The History Test

Compare to organization's past performance.

Template:

"You assume [X]. Last time you attempted [similar thing], it took [Y]. What's changed?"

Example:

"You assume 8 weeks for the microservices migration. Your last infrastructure migration took 5 months. What's different this time?"

The Stress Test

Push assumption to failure point.

Template:

"You assume [X]. What happens when [stress scenario]?"

Example:

"You assume the system handles 10K concurrent users. What happens during a flash sale with 50K? What's the failure mode?"

The Dependency Audit

Trace assumption to its dependencies.

Template:

"For [assumption] to be true, what else must be true?"

Example:

"For your 6-week timeline to work, you need: (1) API specs finalized by week 1, (2) no scope changes, (3) 100% team availability, (4) no production incidents. How realistic is that?"

The Inverse Test

Consider what happens if assumption is wrong.

Template:

"If [assumption] is wrong, what's the impact? What's your Plan B?"

Example:

"If users don't adopt this feature, what's the fallback? Have you defined failure criteria?"


Wishful Thinking Indicators

Red flags that suggest assumption is based on hope rather than evidence:

1. The Optimistic Timeline

  • "Should only take..."
  • "If everything goes well..."
  • "We can do it if we're focused..."

Reality: Things rarely go perfectly. Add 30-50% buffer.

2. The Magical Hiring

  • "We'll just hire..."
  • "Once we have the team..."
  • "We're planning to bring on..."

Reality: Hiring takes 3-6 months for senior roles. Onboarding adds another 2-3 months to productivity.

3. The Simple Integration

  • "It's just an API call..."
  • "Should be straightforward..."
  • "They have good documentation..."

Reality: Integrations always have edge cases, rate limits, and unexpected behaviors.

4. The Obvious Market

  • "Everyone needs this..."
  • "Users have been asking for..."
  • "It's clear that..."

Reality: "Everyone" is not a market segment. Validate with actual user research.

5. The Linear Scaling

  • "If we can do X, we can do 10X..."
  • "We'll scale as needed..."
  • "Growth shouldn't be a problem..."

Reality: Scaling is non-linear. What works at 10K users may fail at 100K.


Output Format

When challenging assumptions, provide:

# Assumption Analysis: [Plan/Proposal Name]

## Summary
- **Total Assumptions Identified**: [Count]
- **High-Risk Assumptions**: [Count]
- **Requires Immediate Validation**: [Count]

## Critical Assumptions (Must Validate Before Proceeding)

### Assumption 1: [Statement]

**Category**: Timeline / Resource / Technical / Business / External
**Stated or Implicit**: Stated / Implicit

**The Problem**:
[Why this assumption is questionable]

**Evidence For**:
- [Supporting evidence]

**Evidence Against**:
- [Counter-evidence]

**If Wrong, Impact**:
- Timeline: [Impact]
- Budget: [Impact]
- Success: [Impact]

**How to Validate**:
- [Validation method]
- [Time required]
- [Cost]

**Verdict**: Valid / Questionable / Invalid / Unknown

---

### Assumption 2: [Statement]
[Same format]

---

## Medium-Risk Assumptions (Should Validate)
[List with brief analysis]

## Low-Risk Assumptions (Monitor)
[List]

## Recommendations

### Before Proceeding
1. [Validation action 1]
2. [Validation action 2]

### Risk Mitigation
1. [Mitigation for assumption 1]
2. [Mitigation for assumption 2]

### Contingency Plans Needed
1. [Plan B for assumption 1]
2. [Plan B for assumption 2]

Integration with Validation

The assumption-challenger skill feeds into the broader validation workflow:

Proposal/Plan
     │
     ▼
[assumption-challenger] → List of assumptions with verdicts
     │
     ▼
[antipattern-detector] → Identified anti-patterns
     │
     ▼
[validation-report-generator] → Final 8-section report

References