The Architect

---
name: the-architect
description: Architecture decisions, trade-off analysis, and ADR authoring. Trigger when a significant technical decision needs to be made, documented, and owned — not when an implementation detail needs a choice.
---

# The Architect

> **Keep the architecture ladder human-owned.** Let the agent draft and diagram, but judgment and sign-off stay with the accountable SME.

This skill is for decisions that persist — the ones that are expensive to reverse, that constrain the system for months, or that affect multiple teams. Implementation details belong in code review. Architecture decisions belong here.

## When to use

- Choosing between two or more structural approaches (database type, service boundary, communication pattern)
- Deciding how to handle a cross-cutting concern (auth, observability, multi-tenancy, data residency)
- Designing an integration boundary between systems
- Anything that warrants an ADR

## Procedure

1. **State the decision to be made** — one sentence. If you cannot state it in one sentence, it is not one decision.

2. **Capture the context** — what forces, constraints, and requirements make this decision necessary? What is the status quo, and why is it insufficient?

3. **Enumerate the options** — at least two credible options. For each:
   - What are the benefits?
   - What are the costs and trade-offs?
   - What does it require from the surrounding system?
   - What is the failure mode?

4. **Run the Adversarial Gate on the leading option** — before committing, invoke `adversarial-gate` on the preferred choice. A clean gate result is a prerequisite for committing to the decision.

5. **State the decision** — which option is chosen and why. The reasoning must reference the context and trade-offs from step 2-3, not just assert a preference.

6. **Record consequences** — what does this decision make easier? What does it make harder? What does it prevent?

7. **Author the ADR** — format:
   ```
   ---
   status: draft
   id: ADR-NNNN
   date: <date>
   deciders: [<handle>]
   ---

   # ADR-NNNN: <short title>

   ## Status
   draft | approved | superseded

   ## Context
   <forces, constraints, why a decision is needed>

   ## Decision
   <the chosen option and reasoning>

   ## Consequences
   <what becomes easier, harder, or foreclosed>
   ```
   A decision's lifecycle is visible in **both** the filename postfix and the `status:`
   field: `ADR/ADR-NNNN-<slug>-DRAFT.md` (`status: draft`) while under review, renamed to
   `ADR/ADR-NNNN-<slug>-approved.md` (`status: approved`) on approval.

8. **Link from the relevant spec, HLD, or PR** — ADRs that are not referenced are not found.

## Cloud vendor routing

When a decision touches a specific cloud, invoke the matching expert skill before
finalising the ADR, and record which guardrail checklist ran:

| Vendor | Skill |
|---|---|
| Google Cloud | `gcp-expert` |
| AWS | `aws-expert` |
| Azure | `azure-expert` |
| Alibaba Cloud | `alibaba-expert` |

Multi-cloud decisions run every relevant checklist; the ADR names them. A cloud
decision without its guardrail checklist is an unreviewed decision.

## Outputs

- `ADR/ADR-NNNN-<slug>-DRAFT.md` → `ADR/ADR-NNNN-<slug>-approved.md` on approval
- Trade-off summary (can be included in the ADR or a separate HLD section)
- Updated `architecture/HLD-<feature>.md` if the decision changes the HLD

## Guardrails

- **One ADR per decision.** Bundling multiple decisions into one ADR obscures accountability.
- **The ADR captures reasoning, not just the outcome.** "We chose Postgres" is not an ADR. "We chose Postgres because our consistency requirements rule out eventual-consistency stores, and our team has no operational experience with Cassandra" is an ADR.
- **Architecture is not implementation.** An ADR about which ORM to use is implementation. An ADR about whether the service owns its own database is architecture.
- **Supersede, do not edit.** When a decision changes, create a new ADR that supersedes the old one. History is the point.