01 / The shape diff

What moved is not the same as what changed.

A geometric comparison can show that a wall shifted, an opening widened, or an area changed. That evidence is necessary, but it does not explain the design decision.

In a BIM workflow, people commonly restore the missing context through comments, issue trackers, meeting minutes, and object names. The project history is divided between the model and the conversation around it.

02 / The semantic diff

Let the code carry the context.

In .muro, use, adjacency, boundary, and passage are source statements. A textual diff can therefore reveal the architectural decision before the geometry is rebuilt.

$ git diff -- before.muro after.muro
- space /L1/work office name:private-office use:exclusive
+ space /L1/work office name:shared-studio use:common
+ boundary /L1/work /L1/court type:open

The change is readable: a private office becomes a shared studio, and its boundary to the courtyard opens. The resulting wall and opening changes are consequences of that decision.

03 / Reviewing intent

Review the decision and its consequences together.

A useful review can begin with the semantic diff, run the build, and inspect every affected projection. The reviewer can ask whether the new use is appropriate, whether the open boundary still satisfies required performance, and whether circulation, area, or enclosure changed unexpectedly.

Git provides durable commits, branches, attribution, and comparison. Koyu gives those mechanisms architectural material worth comparing.

04 / A project memory

A sequence of reasons becomes project memory.

When each commit changes readable spatial intent, history is more than a backup. It becomes a sequence of design decisions that a new collaborator—or an LLM—can inspect.

Commit messages and discussions still matter. Code cannot replace negotiation, judgment, or the social work of design. The aim is narrower: the source should not be mute until a person adds a comment explaining what its geometry means.

05 / What Git does not solve

Version control does not make a design decision correct.

A clean diff can still describe a poor decision. Architectural review requires knowledge of people, climate, regulation, construction, cost, and culture. Git contributes traceability, not authority.

That distinction matters. The promise is not automated consensus. It is a source where people and language models can discuss the same readable change and reproduce its geometric consequences.