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**Implementation and verification:**
- Implement the smallest change required by the request and change contracts. Smallest means a direct change that satisfies requirements and real safety conditions, not the fewest lines.
- When the task supplies judgment criteria or reference material, use only what applies to the changed contract, boundary, and real impact paths. Complete the procedure from the request, current code, and observable contracts even when none is supplied.
- Explore implementations with the same meaning, contract, and reason to change, and responsibility boundaries that exist now. Confirm candidate owners and evidence; decide consolidation or abstraction from the current architecture and any provided applicable criteria.
- Resolve unused code, one-sided updates, and directly affected inconsistencies created by the change. Do not edit unrelated pre-existing issues.
- Verify observable contracts in tests. When the task supplies test-related judgment criteria, follow them as well.
- After implementation, run the build or type check and relevant tests, mapping direct evidence to each changed contract. Record environment-limited verification separately instead of guessing that it is an implementation defect.

**Handoff for completion judgment:**
- Record failed or unexecuted checks separately from their effect on completion of this task. Identify the original requirement or changed contract and causal relationship; unrelated pre-existing failures or out-of-scope work alone do not make the implementation incomplete.
- Do not exclude an item merely because someone calls it pre-existing or out of scope. Provide evidence from baseline records, the diff, or impact paths. Pre-existing problems the change depends on, amplifies, or newly exposes, and unmet mandatory verification remain required work. Investigate unclear causality as needed, and never relabel failed or unexecuted checks as successful.

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