Technical Design Document

[System or Feature Name] — TO-BE Architecture

[One-sentence description of what this document designs and why it matters.]

Status

Draft

Owner

[Team / Engineer]

Systems

[Service A · Service B]

Version

v0.1 — YYYY-MM-DD

TO-BE Design[Domain Tag]

Template instructions — Duplicate this file to src/app/engineering/your-document/page.tsx and replace all bracketed placeholders. Add a nav entry in src/config/nav.ts under the Engineering group. Use <Tag variant="planned"> on headings or table cells to flag TO-BE items, and swap to variant="live" once shipped.

01Purpose & Scope

[Why this design is needed. What problem does the current state create? What outcome does this design achieve?]

In scope — [What this document covers.]

Out of scope — [What is explicitly not covered.]

02Current State (AS-IS)

[Brief description of the current architecture or behaviour. Link to the relevant AS-IS page for full detail.]

Component	Current behaviour	Problem
[Component A]	[What it does now]	[Why this is insufficient]
[Component B]	[What it does now]	[Why this is insufficient]

03Target State (TO-BE) Planned

[Description of the new design. What changes, what stays the same. Use diagrams or a PipelineDiagram where helpful.]

Key decisions

[Decision 1 — why this approach was chosen over the alternatives]
[Decision 2]

04Delta — What Changes

Area	AS-IS	TO-BE
[Area]	[Current]	[Future] Planned
[Unchanged area]	[Current]	No change Live

05Migration Plan

[Step 1 — what needs to happen first and why]
[Step 2]
[Step 3 — cutover / go-live]

Cutover strategy — [How the transition happens with minimal disruption. Rollback procedure if the cutover fails.]

06Risks & Considerations

[Risk name] — [Description and mitigation strategy.]

[Dependency] — [Any preconditions that must be true before this design can be implemented.]

07Success Criteria

[Measurable outcome 1 — how will you know this worked?]
[Measurable outcome 2]

Technical Design Document · Template · YYYY-MM-DDOwner: [Team / Engineer]