SDLC blueprint

Handbook

Spiral Model — ceremonies (prescriptive)

The Spiral Model organizes work around **quadrant transitions** and **anchor-point milestones**. Below: key ceremonies mapped to the four-quadrant cycle.

Spiral Model — ceremonies (prescriptive)

The Spiral Model organizes work around quadrant transitions and anchor-point milestones. Below: key ceremonies mapped to the four-quadrant cycle.

1. Spiral planning (Q1 — objectives)

Intent: C1 + C2.
Inputs Results from previous spiral, stakeholder feedback, updated constraints
Outputs Objectives for this spiral, alternatives identified, risk candidates listed
Participants PM (R), risk analyst (R), architect (R), stakeholders (O)
Timebox Half day to 2 days (scales with spiral scope)

Agenda:

  1. Review previous spiral outcomes and open risks.
  2. Define objectives and success criteria for this cycle.
  3. Identify alternatives and constraints.
  4. Agree on risk-analysis approach for Q2.

2. Risk review (Q2 — identify & resolve)

Intent: C1 + C6 (risk-driven assurance).
Inputs Risk register, prototypes/simulations from prior spirals, new risk candidates
Outputs Prioritized risk list, resolution strategies, go/no-go for Q3 build scope
Participants Risk analyst (R), architect (R), PM (R), domain experts (O)
Timebox 2–4 hours per spiral (more for early spirals with high uncertainty)

Agenda:

  1. Present top risks with likelihood, impact, and evidence.
  2. Review prototype/simulation results addressing prior risks.
  3. Propose resolution strategies (prototype, mitigate, accept, avoid).
  4. Decide build scope for Q3 based on acceptable risk level.

3. Development sync (Q3 — build)

Intent: C3.
Inputs Spiral plan, risk-adjusted scope, design artifacts
Outputs Coordination decisions, blocked items escalated
Participants Dev team (R), architect (R), PM (O)
Timebox 15–30 min (daily or as needed)

Within Q3, teams may use any development approach (Agile iterations, focused build phases) appropriate to the spiral's scope and risk profile.

4. Prototype demo

Intent: C4 + C6 (risk reduction evidence).
Inputs Working prototype addressing identified risks
Outputs Risk resolution evidence, stakeholder feedback, refined requirements
Participants Dev team (R), architect (R), stakeholders (R), risk analyst (R)
Timebox 1–2 hours

Prescriptive rule: Prototypes exist to reduce risk, not to become production code. Document which risks the prototype addresses and what was learned.

5. Anchor-point milestone review (Q4)

Intent: C4 + C1 (commitment gate for next spiral).
Inputs Spiral deliverables, risk register status, evidence packages
Outputs Stakeholder commitment (go / no-go / redirect), updated objectives for next spiral
Participants Stakeholders (R, decision), PM (R), risk analyst (R), architect (R), dev team (R)
Timebox 2–4 hours

Anchor-point milestones (Boehm)

Milestone When Decision
LCO — Life Cycle Objectives After initial spirals Are objectives clear, feasible, and worth pursuing?
LCA — Life Cycle Architecture After architecture spirals Is the architecture sound and risks manageable?
IOC — Initial Operational Capability After build spirals Is the system ready for operational use?

6. Retrospective

Intent: C5.
Inputs Spiral execution data, risk prediction accuracy, schedule variance
Outputs Process improvements for next spiral, updated risk-analysis practices
Participants PM (R), dev team (R), risk analyst (O), architect (O)
Timebox 1–2 hours

Spiral twist: Compare predicted vs actual risk outcomes. Improve the team's risk identification and estimation capability, not just engineering practices.

7. Quick I/O summary

Ceremony Primary output
Spiral planning Objectives, alternatives, risk candidates
Risk review Prioritized risks, resolution strategies, build scope
Dev sync Coordination, unblocked items
Prototype demo Risk resolution evidence, refined requirements
Anchor-point review Stakeholder commitment, next-spiral direction
Retrospective Process and risk-estimation improvements

Canonical source

Edit https://github.com/autowww/blueprints/blob/main/sdlc/methodologies/spiral/ceremonies-prescriptive.md first; regenerate with docs/build-handbook.py.