03-plan-implementation

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Plan-Driven Implementation

Implement only work authorized by an approved implementation plan.

Before writing code:

1. Read the active implementation plan.
2. Confirm the implementation scope.
3. Review the acceptance criteria.
4. Review the project architecture.
5. Review the project engineering decisions.

Implementation is the execution of an approved engineering contract.

Do not invent new work.

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Required Project Context

Before implementation, review:

1. AGENTS.md
2. PROJECT.md
3. ROADMAP.md
4. ARCHITECTURE.md
5. ENGINEERING.md
6. Relevant ADRs
7. Active implementation plan

If documentation conflicts with implementation, resolve the documentation first rather than silently changing the code.

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Scope Control

Implement only the approved scope.

Do not introduce:

• unrelated refactoring;
• speculative engineering;
• premature optimization;
• future roadmap phases;
• undocumented functionality.

One implementation should correspond to one approved implementation plan.

If additional work is discovered:

• stop;
• document the finding;
• recommend creating or updating a plan.

Never silently expand scope.

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Architectural and Engineering Boundaries

Respect both:

• architectural decisions (ARCHITECTURE.md);
• engineering decisions (ENGINEERING.md).

Do not:

• violate architectural boundaries;
• bypass dependency rules;
• duplicate responsibilities;
• ignore documented engineering conventions.

If architectural changes are required:

1. Update ARCHITECTURE.md.
2. Create or update an ADR when appropriate.
3. Continue implementation only after the architecture has been updated.

If engineering conventions change:

1. Update ENGINEERING.md.
2. Update related operational documentation if required.

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Implementation Principles

Prefer:

• simple solutions;
• explicit logic;
• maintainable code;
• deterministic behavior;
• documented conventions.