# ADR-0006: Prefer Proven Algorithms and Require Owner Approval Before Custom Algorithms

- **Status:** Approved
- **Decision owner:** Girish
- **Decision:** Use proven, well-tested algorithms, libraries, and patterns by default
- **Implemented:** Governance rule

## Context

Axiom will rely on research, scanning, ranking, scoring, learning, deduplication, trading signals, AI reasoning workflows, and future analytics engines. These areas can affect evidence quality, risk posture, capital safety, and system trust.

Custom algorithms increase model risk, implementation risk, validation burden, and governance complexity. Axiom should only introduce custom algorithms when proven approaches are inadequate and the owner has explicitly approved the exception.

## Decision

Axiom will use proven, well-tested algorithms, libraries, and patterns by default.

Do not invent, design, or introduce any custom algorithm unless:

1. Existing proven approaches were evaluated first.
2. The limitation is documented.
3. The proposed custom approach is explained clearly.
4. Risks and trade-offs are listed.
5. Girish reviews and approves it before implementation.

This applies to research, scanning, ranking, scoring, learning, deduplication, trading signals, AI reasoning workflows, and any future analytics engine.

## Consequences

- Engineering defaults to established libraries and documented methods.
- Custom algorithm proposals require evidence and explicit owner approval before implementation.
- Reviews must check whether a proposed algorithm is proven, library-backed, or an approved exception.
- Future analytics work must document evaluated alternatives before custom logic is accepted.

## Exception Record

Any approved custom algorithm must record:

- the proven approaches evaluated;
- why those approaches are insufficient;
- the proposed custom method;
- validation requirements;
- operational risks;
- trade-offs;
- Girish's approval.

## Boundaries

- This ADR does not prohibit routine application logic, adapters, orchestration, or glue code.
- This ADR does prohibit unapproved custom analytical methods where proven approaches exist.
- Schedule pressure is not a valid reason to bypass this rule.