tutti-test-audit

# Tutti Test Audit Make every changed test earn its maintenance cost. A green test, a coverage increase, or a larger test count is not a quality verdict. Read the root and closest scoped `AGENTS.md`, then read `docs/conventions/unit-testing.md` before a non-trivial test change or review. Follow `docs/conventions/testing.md#validation-selection` for commands and validation scope. ## Establish the evidence map Before editing, inspect: 1. the production owner, public entry point, relevant caller and callee; 2. sibling implementations that share the same invariant; 3. existing tests, fixtures, conformance suites, and repository checks; 4. the changed-aware and platform lane that will select the evidence; 5. relevant history for a regression or a suspicious existing test. For Agent Host lifecycle semantics, also read `packages/agent/host/README.md` and start with the conformance contract. Do not reimplement lifecycle tests in an adapter. ## Pass the authoring gate Answer all six questions before adding or materially rewriting a test: 1. **Protected contract:** What observable behavior, invariant, compatibility promise, or prior failure matters? 2. **Credible failure:** What plausible faulty implementation must make the test fail? 3. **Coverage gap:** Why would existing evidence not catch that failure? Can an existing table, scenario, or fixture express it without duplication? 4. **Owner and observer:** Which module owns the decision, and what is the lowest bou...