Three follow-ups the review caught in the stray-capture rewrite, plus a cost
undercount shared with the log ledger.
Seal the stray fragment list into blocks past MAX_PENDING_CHUNKS, mirroring the
fd-3 reader: a program pacing single-byte os.write(1, ...) calls otherwise
accumulates one live Buffer per write, and the per-object overhead no byte
count sees exhausts the host heap far below the budget.
Flush the residual by its running SERIALIZED cost (serializedBufferCost, a
per-byte lower bound) rather than raw byte count: a control-char-dense
newline-free flood serializes several-fold, so a raw-byte threshold let it grow
to a full budget's worth of raw bytes — up to ~6x what the ledger admits —
before flushStray concat/decoded the whole ~256 MiB residual at once.
Charge a lone surrogate its full six escaped bytes (\uXXXX under ES2019
well-formed JSON.stringify) in both jsonStringCostUpTo and serializedBufferCost,
not the three bytes Buffer.byteLength reports for U+FFFD: a forged log frame
flooding \ud800 escapes was undercharged by half and admitted ~2x maxLogBytes.
Key the sync-spawn leak assertion off the exact bootstrap path from the mocked
spawn's argv, immune to a sibling worker's concurrent staging. Refresh the
stale load-check comment that named the replaced JSON.stringify mechanism.
Add lone-surrogate, stray-sealing, and companion regression tests (per-file
100% coverage); update the Agent Note and zh pair.
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