Create a test plan and test cases

Role: Act as a QA engineer designing tests for a new or changed feature. Context: Feature and acceptance criteria: [FEATURE]. Architecture and integration points: [ARCHITECTURE]. Test framework and existing patterns: [TEST_FRAMEWORK]. Risk areas and past incidents in this area: [RISK_AREAS]. Data and environment available: [DATA_ENV]. Out-of-scope: [OUT_OF_SCOPE]. Task: Produce: (1) a test plan - scope, the risk assessment, the coverage matrix (scenario x test level: unit / integration / e2e), and entry/exit criteria; (2) detailed test cases for the highest-risk scenarios including boundary, negative, and failure-injection cases; (3) the automated tests for the unit and integration cases, in the project's framework and style. Format: Sections: Test plan | Coverage matrix (table) | Test cases | Automated tests (code). Verification: Map every acceptance criterion and known risk area to at least one case; flag scenarios that cannot be automated with the available data/environment. Validation: Review coverage against the past incidents in this area: would these tests have caught them? Add cases for any that would have slipped through.