SDLC blueprint

Handbook

Spiral Model — connection to the SDLC foundation

The Spiral Model treats each development cycle as a **risk-driven** pass through planning, risk analysis, engineering, and evaluation. The blueprint's **A–F** phases still apply; the Spiral adds **exp

Spiral Model — connection to the SDLC foundation

The Spiral Model treats each development cycle as a risk-driven pass through planning, risk analysis, engineering, and evaluation. The blueprint's A–F phases still apply; the Spiral adds explicit risk gates and iterative deepening across multiple passes.

1. SDLC phases A–F (how Spiral maps)

Each spiral is a partial or full pass through A–F, with increasing fidelity:

Phase Spiral expression Notes
A — Shape Q1: Determine objectives, alternatives, constraints Each spiral refines scope based on prior learning
B — Plan Q1 + Q4: Plan the approach for this cycle; select risk-reduction strategy Early spirals may plan only a prototype; later spirals plan full build
C — Build Q3: Develop the increment (prototype, partial, or full) Scope matches the risk profile of this spiral
D — Verify Q3: Test and validate against objectives Verification depth matches the spiral's maturity
E — Release Q4: Stakeholder review; anchor-point milestone if applicable Release may be internal (demo) or external (IOC)
F — Operate & learn Q4 → next Q1: Feedback from this spiral feeds objectives for the next Learning is systematic, not incidental

Prescriptive rule: Every spiral must pass through Q2 (risk analysis) before committing resources to Q3 (build). Skipping risk analysis defeats the model's purpose.

Spiral teams maintain the blueprint tracking spine across spirals:

Artifact Spiral mapping
Intent / request Objectives defined in Q1 of each spiral
Spec Evolves across spirals; early specs may be high-level concepts, later specs are detailed
Plan Spiral plan (Q1+Q4); includes risk-reduction approach
Tasks Engineering tasks within Q3
PRs Implementation within Q3; link to risk items resolved
Reviews Q4 stakeholder review; anchor-point milestones
Release IOC or operational release in later spirals

Prescriptive rule: Maintain a risk register as a first-class artifact alongside the tracking spine. Each spiral should reference risks addressed and residual risks carried forward.

3. Ceremony intents (C1–C6) ↔ Spiral quadrants

Intent Spiral practice Notes
C1 — Align & decide Q1: Objectives workshop; stakeholder alignment on goals and constraints Each spiral re-aligns based on prior results
C2 — Plan the slice Q1 + Q4: Spiral planning; commitment to risk-reduction approach Commit to the approach, not just the deliverable
C3 — Execute & unblock Q3: Development coordination; risk-driven prioritization Address highest-risk items first within the spiral
C4 — Review & quality Q4: Stakeholder review; anchor-point milestone evaluation Evidence-based review; prototype demos for early spirals
C5 — Reflect & improve Q4: Lessons learned; process improvement across spirals Compare actual vs predicted risk outcomes
C6 — Knowledge share Q2: Risk analysis results; Q4: milestone evidence packages Risk knowledge is critical cross-spiral context

See ceremony foundation and methodology bridge.

4. Role archetypes (blueprint hats on a Spiral team)

Spiral role Typical archetype emphasis Notes
Project manager Orchestrator Plans spirals; coordinates stakeholders; manages schedule and resources
Risk analyst / chief engineer Quality advocate + Orchestrator Drives Q2 risk identification and resolution strategy
Chief architect Implementer + Quality advocate Technical decisions; architecture evolution across spirals
Development team Implementer Executes Q3 within the risk-driven plan
Stakeholders / sponsors Sponsor proxy + Steer Commit resources at anchor-point milestones

Detail: Roles, archetypes & methodology titles, Spiral roles chapter.

5. What Spiral adds beyond the foundation

  • Risk-driven iteration — risk analysis gates every cycle.
  • Anchor-point milestones — LCO, LCA, IOC structure stakeholder commitment.
  • Flexible process — each spiral can contain any sub-process (prototype, waterfall phase, Agile iteration).
  • Cumulative progress — the model explicitly tracks increasing investment and fidelity.

6. Anti-patterns (prescriptive "don't")

Anti-pattern Fix
Skipping risk analysis in Q2 Q2 is the model's core value; without it, you have uncontrolled iteration
Treating every spiral identically Early spirals are exploratory (prototypes); later spirals are engineering-grade
No stakeholder commitment at anchor points Anchor-point reviews prevent runaway investment; insist on explicit go/no-go
Using Spiral for low-risk projects Overhead may not be justified; consider Agile or phased delivery instead

7. References in-repo

Canonical source

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