implement.md spawns implementer agents in parallel batches, all appending to
the same implementation-log.md. Dogfooding showed agents satisfying 'Append
result to:' with a full-file Write — the last writer clobbered 4 of 6 entries.
Pin the mechanism in both contracts: append with Bash >> heredoc, never the
Write/Edit tool on the shared log. Shape tests pin the instruction in both
files (empirically verified: agents given the >> instruction appended safely).
Co-Authored-By: Claude Fable 5 <noreply@anthropic.com>
Kjell Tore Guttormsen
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