Implement the work the user points you to: an issue, or the prompt itself.

When there is no issue, the prompt and the conversation are the source. If the user ran /restate, the corrected restatement is.

When there is an issue, read the whole issue with its comments (gh issue view <n> --comments), and the parent spec in full when the issue is a delivery of one. A summary of the issue makes you build the summary.

When there is a spec, respect its invariants. If you disagree with a decision in the spec, argue it in the PR instead of changing it on your own. The spec is what the reviewer checks your code against; a silent change leaves it describing something else, and a regressing spec implemented in silence is no better. Stopping to ask about an ambiguous instruction is worth more than obeying it.