05 Architecture Decision Records

Architecture Decision Records Skill

Use When

• Use when recording a consequential architecture choice, context, options, rationale, consequences, owner, and supersession path. Use ai-adr-catalogue for AI-system decisions and formal-review-gates for approval checkpoints.

Do Not Use When

• Do not use for trivial implementation choices that do not affect system structure, cost, or future flexibility.
• Do not use this skill to fabricate missing project facts, legal conclusions, test results, approvals, or certification claims.

Required Inputs

Capability and permission boundaries

Default to read-only. Read and search access to the supplied artefacts are required. Editing is limited to an explicitly authorised requested draft or project files. Execute validation only when authorised; publishing, signature, certification, production mutation, destructive action, spending, and risk acceptance require explicit authority.

Degraded Mode

When files, tools, network, rendering, fonts, execution, or evidence are unavailable, return the narrowest useful qualified draft or finding set. Name every unavailable check and its consequence; an unassessed check is never a pass. Preserve evidence already gathered and provide the exact next verification step.

Decision Rules

Workflow

1. Confirm the requested artefact, audience, scope, decision owner, and applicable baseline or version. Work read-only by default; source mutation, publication, signature, certification, production change, or risk acceptance requires explicit authority.
2. Inspect every required input and record missing, stale, conflicting, or inaccessible evidence. Stop claims that depend on an unresolved required input.
3. Apply the Decision Rules, then execute the existing Core Instructions below in order; preserve project terminology and trace each material statement to its source.
4. Test the draft against the output acceptance conditions and domain quality standards. If a check cannot run, mark it not assessed and never convert it into a pass.
5. On failure, recover by preserving completed evidence, identifying the narrowest corrective action and owner, and rerunning only the affected checks before handoff.
6. Produce the named artefact and evidence record; publish, sign, certify, mutate production, or accept risk only under explicit authority.

Outputs

Evidence Produced

Quality Standards

• Every ADR has status, decided_on, deciders; every superseded_by points to a real ADR; every catalog entry has a matching file.
• Use deterministic acceptance conditions and preserve traceability from source to decision and output.
• Separate facts, inferences, assumptions, and approvals; never present one as another.
• Apply 28-anti-ai-slop during authoring and 29-ai-slop-audit at major checkpoints and release.

Anti-Patterns

• Producing Architecture Decision Records from assumptions instead of named project sources. Fix: Cite the source or mark the item unverified.
• Treating a missing or inaccessible check as passed. Fix: Mark it not assessed, state impact, and block dependent claims.
• Using vague gates such as adequate, secure, or user-friendly. Fix: Replace each with an observable criterion, threshold, and evidence source.
• Copying a generic template without product, control, role, version, or jurisdiction detail. Fix: Ground every section in the supplied context and remove unused boilerplate.
• Publishing, signing, certifying, changing production, or accepting risk without authority. Fix: Prepare a draft and route the decision to the accountable owner.
• Listing evidence without provenance or an acceptance result. Fix: Record source, period, integrity check, mapping, and pass/fail/not-assessed status.

Worked Example

Example: if a required source, owner, obligation, or acceptance condition is missing, stop the affected claim and record the gap. Record the evidence and result in the validation record; this avoids unsupported governance artefact.

References

• Repository operating rules: apply the engine's routing, evidence, and release gates.

SaaS mode: if the project is a multi-tenant SaaS, see references/saas-adr-catalogue.md for the expected ADR families.

Overview

This skill produces one Architecture Decision Record (ADR) per significant architectural choice and registers it in the project ADR catalog. The catalog is the auditor-facing index the Phase 09 gate reconciles against the filesystem.

When to Use This Skill

• When the team commits to a major technology choice (database, queue, language runtime).
• When deviating from a baselined constraint, standard, or reference architecture.
• When deprecating or superseding an earlier architectural decision.
• When a decision affects multiple modules, teams, or the cost model.

Inputs

• Decision title and one-paragraph context.
• Options considered (at least two) and the selected option.
• Rationale: forces, trade-offs, and consequences.
• Deciders (role names) and decision date.

Stimulus / Process / Response

1. Stimulus: a decision point surfaces during design, review, or an incident post-mortem.
2. Process:
   1. Select the next sequential ID ADR-NNNN.
   2. Write the ADR file under projects/<ProjectName>/09-governance-compliance/05-adr/NNNN-slug.md.
   3. Append the entry to projects/<ProjectName>/_registry/adr-catalog.yaml.
   4. If the decision supersedes a prior ADR, set the prior entry's status: superseded and its superseded_by field.
3. Response: one new ADR file plus one catalog entry, reconciled by AdrCatalogCheck.

Output Contract

• File: projects/<ProjectName>/09-governance-compliance/05-adr/NNNN-<slug>.md — content follows the ADR template.
• Registry: projects/<ProjectName>/_registry/adr-catalog.yaml — validated against engine/registry/schemas/adr-catalog.schema.json.

Status Lifecycle

• proposed — drafted but not yet ratified by deciders.
• accepted — ratified; in force.
• deprecated — no longer recommended but not replaced.
• superseded — replaced by another ADR; superseded_by field MUST point to an existing catalog ID.

Catalog Format

adrs:
  - id: ADR-0001
    title: "Use PostgreSQL 15 as the primary RDBMS"
    status: accepted
    decided_on: 2026-04-16
    deciders: ["Chief Architect", "Tech Lead"]
    affects: ["03-design-documentation"]

Worked example

See examples/representative/.