Stage 3
If margins break at scale, the model fails.
Use this stage to test whether revenue, cost, and founder load can support real growth.
Use this before scale, fundraising, new hiring, or committed operating spend.
Diagnostic module
Stage doctrine
This explanation layer clarifies the Business Model Fit methodology while leaving evaluator scoring and runtime behaviour untouched.
Methodology
Economics before scale confidence
Business Model Fit checks whether revenue, cost structure, and founder load still hold when the team moves from product pull into operational scale decisions.
Scoring
Observed economics outrank projections
ProductBooks prioritises traceable acquisition cost, contribution margin, durable revenue, and dependency signals over blended assumptions or future-looking optimism.
Decision boundary
Scale does not forgive fragility
If growth depends on founder rescue, hidden cost, or weak unit economics, the system keeps the model unresolved until the evidence is strong enough to support scale.
Diagnostic module
Problem to Product to Business Model
The system advances upward only when the lower layer holds under evidence.
Problem
01Problem–Solution Fit
If the problem is weak, every signal above it misleads.
Product
02Product–Market Fit
If users do not return, you do not have product–market fit.
Business Model
03Business Model Fit
If margins break at scale, the model fails.
If one layer breaks, every layer above it becomes less trustworthy.
- Weak problem evidence invalidates product confidence.
- Weak product pull invalidates business confidence.
Diagnostic module
Current Stage
Use this stage before scale, spend, or fundraising
Model layer
Business Model Fit
System state
Current layer
Evidence quality
In review
Risk weighting
Moderate
Operational recommendation
If the economics depend on founder effort or fragile margins, the model is not ready.
Next action
After product pull exists and before you treat growth as durable.
How ProductBooks works
- Run the evaluator.
- Identify what still scores zero.
- Generate the missing evidence.
- Re-run the same stage before moving on.
Diagnostic module
What this stage decides
Keep the decision boundary narrow. Everything outside it stays outside.
Decides
Whether unit economics support sustainable operation.
Does not do
Optimise pricing strategy.
Decides
Whether costs hold as revenue grows.
Does not do
Improve margins for you.
Decides
Whether revenue persists beyond founder effort.
Does not do
Help you "pass".
Diagnostic module
Evidence Rules
Strict rules only. No interpretation layer.
What counts
- Observed unit economics before projections.
- Traceable acquisition cost before blended assumptions.
What fails fast
- Durable revenue before one-off selling.
- Missing proof still blocks scale confidence.
Diagnostic module
System references
Use the linked stages, report, tools, and evidence definitions as a connected operational framework.
Diagnostic module
Generate Missing Evidence
Operators generate proof. They do not soften the verdict.
Unit Economics Reality Operator
GENERATEMeasure whether each customer produces positive contribution margin from observed data.
Improves
The scoreable gaps this evaluator surfaced.
CAC Traceability Operator
GENERATETrace acquisition cost back to specific customers and acquisition actions.
Improves
The scoreable gaps this evaluator surfaced.
Revenue Durability Operator
GENERATEMeasure whether revenue persists without repeated manual sales effort.
Improves
The scoreable gaps this evaluator surfaced.
Founder Dependency & Load Operator
GENERATEMeasure whether the model still holds when the founder steps out of the loop.
Improves
The scoreable gaps this evaluator surfaced.
Primary action
Run Business Model Fit
Start with evidence you can show. Missing proof still scores zero.
Diagnostic module
Command path
Once the model holds, consolidate the system into one report.
Use the Fit Report Generator to combine stage verdicts, evidence gaps, and next actions into a single system view.
Go to Fit Report