Merge train: #9647 #9648 #9649 (llhttp differential closes #9611) - #9653
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September 3, 2026 21:13
…bits (#9611) Closes the last open verification item on #9611 — the llhttp differential — and fixes the bug that verification found. THE DIFFERENTIAL. `crates/perry/tests/issue_9611_llhttp_differential.rs` drives both WebAssembly builds of llhttp that undici ships, the way undici drives them: a windowed `Uint8Array` over the engine's linear memory is filled with the socket chunk, `llhttp_execute` runs, and the parser calls back into JS. It covers whole-message, byte-at-a-time and 4 KiB chunkings of simple, chunked, pipelined, 100-continue, many-header and 300 KiB-body responses, and reads every callback span BOTH out of linear memory and through undici's own trick of mapping the wasm pointer back into the source chunk — a span that is right in one view and wrong in the other fails loudly instead of silently agreeing with itself. node's trace is the checked-in oracle; both builds reproduce it identically. THE BUG IT FOUND. The wasm host held the imports object as raw NaN-boxed bits (`perry_wasm_host_instance_set_import_context`), and nothing rooted or rewrote them. A collection triggered INSIDE one import callback relocated the object, so every later import in the same call resolved a stale pointer, `call_wasm_import` returned 0, and the host substituted the import's default result — wasm continued with no error reported anywhere. Through llhttp that silently dropped `on_message_complete`: a truncated HTTP response reported as a clean parse, on cc's network path. It is not a regression from the zero-copy change. The same binary shape reproduces on a perry built from `666481e27` (the commit before #9611 landed), and the minimiser isolates it to allocation volume inside the callback, not to memory growth: big_nobuild body=307200 build=false pages=3->6 complete=1 big_build body=307200 build=true pages=6->6 complete=0 and tenuring the imports object before instantiation — so a copying minor cannot move it — restores complete=1 on every run. That is the diagnosis. THE FIX. The host now holds an opaque token; the imports object stays on the runtime side in `WASM_IMPORT_OBJECTS`, which a registered scanner rewrites when a collection moves it. The token is assigned at instantiation, so the start function is covered too, and the per-call `perry_wasm_host_instance_set_import_context` store is gone — one less FFI call on the export path. The scanner is rewrite-only (`visit_metadata_nanbox_f64_slot`), matching the memory binding beside it: every path that can reach an import already roots the imports object on the stack, so this table is a lookup side table, not the reference that keeps the object alive. Marking would instead pin the imports object of every instance ever created. Verified on Linux: byte-identical to node on both llhttp builds; the wasm ESM suite, 14 wasm-host tests and 3,037 runtime tests pass; the root-holder and file-size gates pass. Disabling only the rewrite fails the new test at exactly the right line: node : message_complete perry: execute len=307243 ret=0 errpos=-76384 Claude-Session: https://claude.ai/code/session_01VxP3FEDgV4zUocSDBhD8qh
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Lands three fixes, all cherry-picked clean:
Validation:
run_lint_gates.shall 62 gates pass; release build green; RUST_TEST_THREADS=1 perry-runtime 3060/0;issue_9611_llhttp_differentialgreen (215s).Rebase-merge preserving authorship.