feat(net): name the req/resp allocation bounds and prove the wire-size theorem - #75
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…e theorem Deliver #70: closed-form allocation constants derived from the proven NET-1/NET-2 acceptance bounds, as the basis for an upstream normative preallocation proposal. - varintSize models encode_varint's LEB128 byte count (varint.py); varintSize_le_of_lt_pow bounds it by the 7-bit group count. - MAX_COMPRESSED_PAYLOAD_SIZE (12,234,410 B): snappy worst-case expansion of a maximal in-bound payload, matching the reader gate. - MAX_LENGTH_PREFIX_SIZE (4 B): any accepted declared length encodes in at most 4 varint bytes (128^4 > MAX_PAYLOAD_SIZE). - MAX_REQUEST_WIRE_SIZE (12,234,414 B) with request_wire_bound: for any accepted request, length prefix plus compressed payload fit in the constant — for every decompressor, so a conforming client may preallocate exactly this much per req/resp stream and under-allocation is impossible by theorem.
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Summary
Delivers #70 (promote proven req/resp payload bounds to normative allocation constants).
New file
LeanSpec/Networking/Allocation.lean, building on NET-1/NET-2 (payload_size_bound,compressed_size_bound):varintSize— LEB128 byte count, mirroring upstreamvarint.py'sencode_varint7-bit-group loop, withvarintSize_le_of_lt_pow.MAX_COMPRESSED_PAYLOAD_SIZE= 12 234 410 bytes (rfl-proved closed form): snappy's worst-case expansion (n + n/6 + 1024) of a maximal in-bound payload.MAX_LENGTH_PREFIX_SIZE= 4 bytes: any declared length the reader can accept encodes in ≤ 4 varint bytes (128^4 > MAX_PAYLOAD_SIZE).MAX_REQUEST_WIRE_SIZE= 12 234 414 bytes, with the headline theoremrequest_wire_bound: for any request the reader accepts, varint prefix + compressed payload fit in the constant — for every decompressor (snappy enters the model as a parameter).This is the machine-checked basis for the upstream proposal (spec-feedback.md format): "clients MAY preallocate 12 234 414 bytes per req/resp stream; a conforming reader never buffers more". Under-allocation is impossible by theorem; over-allocation is waste the constant eliminates.
All theorems sorry-free;
lake buildpasses.Closes #70