v0.0.189

Changed

• The UTF-8 "safe decode" invariant now lives in one helper (#592). Six sites decoded WASM-memory bytes with errors="replace" so a corrupt String (ptr, len) pair from an upstream codegen bug surfaces as U+FFFD rather than a raw Python UnicodeDecodeError escaping wasmtime's trampoline as a "python exception" cause — the #516 / #522 / #589 contract that a user-level program never produces a Python traceback. The invariant was re-implemented at all six (host_print / host_stderr / host_contract_fail / the String-return extractor in vera/codegen/api.py, _read_wasm_string in vera/runtime/heap.py, and _read_string in vera/wasm/markdown.py) and guarded by six structural source-grep tests plus one end-to-end test covering only host_print — so five of the six sites had no behavioural coverage, and the greps would break under exactly the refactor the issue proposed. The errors="replace" decode now lives in one place — a new vera.runtime.text.safe_utf8_decode (the ROADMAP Tier-2 single-source-of-truth theme, same class as the #828 error-code registry) — reached only through a shared _slice_and_decode helper (vera/runtime/heap.py) that the three WASM-memory string readers (_read_wasm_string and a new _read_string_export there, and markdown _read_string) delegate to. The host_print / host_stderr / host_contract_fail host imports and the String-return extractor route through those readers instead of decoding inline, so no bytes(...).decode(...) call survives outside _slice_and_decode (a net simplification of execute() — the closures no longer re-implement the memory read). The six structural greps are replaced by one helper unit test plus three end-to-end tests that wire the production readers (_read_wasm_string, _read_string_export, markdown _read_string) over a memory region seeded with invalid UTF-8, so a strict-decode regression surfaces as a UnicodeDecodeError escaping the trampoline — caught at one point per reader rather than needing a grep per call site, and transitively covering the host imports / extractor that route through them; the host_print end-to-end test is retained to pin the trampoline fact itself, independently of the production path. Behaviour-preserving. (The network-response decode sites in http.py / inference.py are a separate, already-resolved family — #591, closed — with deliberate per-site handling (errors="replace" for Http.get / Http.post; intentionally strict for Inference.complete, so a non-UTF-8 LLM response fails as a structured Result::Err rather than silently gaining U+FFFD), pinned by their own TestNetworkResponseUtf8Hygiene591 class; they are outside this WASM-memory helper's scope by design.)