Template – Architectural Trade-Off Agreement¶
“Every architecture decision is a trust transaction.”
Purpose¶
The Architectural Trade-Off Agreement (ATA) formalizes critical architectural and non-functional decisions made jointly by Client and Vendor organizations.
It enforces the 3SF principle “Shared Accountability” by documenting, validating, and co-signing the trade-offs that shape long-term product sustainability, cost, and risk.
This agreement ensures that architecture decisions are transparent, reasoned, and aligned with contextual constraints defined in the Engagement Context Canvas. It becomes an auditable artifact for future governance reviews and maturity assessments.
Scope and Application¶
| Dimension | Scope |
|---|---|
| SDLC Stages | Discovery → Design → Early Delivery |
| 3SF Relationship Lines | Engagement ↔ Delivery ↔ Value |
| 3SF Layers | Stable Rules Layer (SRL) + Rule Audit Checklist (RAC) |
| Maturity Target | From Collaborative Confidence → toward Co-Creative Trust |
Contract Parties and Roles¶
| Role | Representative | Responsibility |
|---|---|---|
| Client Solution Architect | [Name, Title] | Defines architectural constraints and business risk boundaries. |
| Vendor Solution Architect | [Name, Title] | Proposes solution options and validates trade-offs. |
| Client Product Leader | [Name, Title] | Confirms business impact of architectural choices. |
| Vendor Delivery Facilitator | [Name, Title] | Ensures chosen architecture supports delivery flow and quality targets. |
Agreement Structure¶
Each ATA records one or more architectural decision packages, following a consistent structure:
| Decision ID | Description | Trade-Off Options Considered | Selected Option | Rationale & Expected Benefit | Accepted Risks | Sign-Off |
|---|---|---|---|---|---|---|
| ATC-01 | API Gateway Technology | (1) Cloud native, (2) Hybrid on-prem, (3) Managed service | Managed service | Simplifies maintenance, accelerates go-live | Vendor dependency, higher cost | CL-SA / V-SA |
| ATC-02 | Data Storage Pattern | (1) Single DB, (2) Sharded DB, (3) Data lake | Sharded DB | Improves scalability for expected traffic | Higher operational complexity | CL-SA / V-SA |
Each trade-off entry must specify benefits, risks, and mitigations, and be co-signed by both Solution Architects.
Agreement Clauses¶
Clause 1 – Transparency of Trade-Offs¶
All major design decisions with long-term cost or quality implications must be recorded in this agreement before implementation.
No change may be executed without mutual awareness of trade-offs.
Clause 2 – Shared Accountability for Risk¶
Both parties share accountability for approved architectural risks.
If a decision causes downstream cost or performance degradation, mitigation responsibilities are executed jointly.
Clause 3 – Alignment with Context¶
All trade-offs must reference the Engagement Context Canvas (ECC) and its six contextual drivers.
Deviations require justification and Executive Sponsor approval.
Clause 4 – Change Management¶
New or modified architectural decisions must be reviewed in governance cadence and appended to the ATA log with version control.
Clause 5 – Review and Renewal¶
ATAs are reviewed during Quarterly Assessments or after major releases.
Findings feed into the Maturity Growth Contract and Relationship Evolution Contract.
Inputs / Outputs¶
| Inputs | Outputs |
|---|---|
| Solution design documents, NFR list, risk register | Architectural Trade-Off Agreement, signed decision log, versioned history of changes |
Metrics / Signals¶
| Category | Example Indicators |
|---|---|
| Decision Traceability | 100% of major design decisions logged and co-signed. |
| Risk Awareness | ≥90% of known architectural risks linked to mitigation actions. |
| Reassessment Cadence | All ATAs reviewed at least once per quarter. |
| Maturity Signal | Decline in technical conflicts and re-work due to unaligned design decisions. |
Common Pitfalls¶
- Recording trade-offs retrospectively (“documenting what was already done”).
- Client and vendor architects failing to sign decisions jointly.
- Ignoring non-functional aspects (security, maintainability, scalability).
- Treating ATAs as compliance paperwork rather than learning artifacts.
- Neglecting to review ATAs after contextual changes or new releases.
Contract Lifecycle¶
| Stage | Action | Responsible Roles |
|---|---|---|
| Creation | Draft during design workshops and approve before major implementation. | Solution Architects |
| Activation | Integrate into Delivery Charter and share with engineering teams. | Delivery Facilitator |
| Review | Validate quarterly or post-release. | Governance Officer / Engineering Director |
| Renewal | Update when architecture evolves or risk profile changes. | Solution Architects / Account Lead |
Client-Side Application¶
Objective: Ensure architectural governance reflects informed business risk and supports long-term sustainability.
Client actions¶
- Require ATAs for all major technical or NFR decisions.
- Validate that trade-offs align with business priorities.
- Co-sign every approved decision and store it in governance repository.
- Participate in quarterly architecture reviews.
Vendor-Side Application¶
Objective: Maintain transparency and shared ownership for design quality and sustainability.
Vendor actions¶
- Facilitate trade-off workshops and maintain the ATA register.
- Communicate rationale and impact clearly to client stakeholders.
- Track deferred risks and mitigation progress.
- Present ATAs during governance and audit sessions.
Summary¶
The Architectural Trade-Off Agreement is the foundation of technical trust in 3SF.
It replaces implicit understanding with explicit, co-signed accountability, ensuring that every architectural choice is transparent, reasoned, and traceable.
When used consistently, this agreement aligns architecture with business value and maturity — turning design discussions into a shared governance discipline rather than a technical debate.