这是一篇由原始材料转换而来的阅读页，保留了源文件的主要结构，并补充了可追溯的来源说明与链接。

Architecture invariants

These are rules the repository should enforce mechanically where possible.

Layering

• Code may only depend on approved adjacent layers.
• Cross-domain access must go through explicit interfaces.

Boundary validation

• Parse and validate external inputs at boundaries.
• Do not rely on guessed payload shapes.

Observability

• New runtime-critical flows should emit structured logs.
• Important async or long-running operations should expose metrics or traces.

File hygiene

• Keep files below the agreed size limit.
• Prefer shared utilities over duplicated local helpers.

Agent readability

• Important workflows must be discoverable from docs/index.md.
• Repeated shell sequences should become scripts.
• Critical decisions should live in versioned docs or plans, not chat history.