Fix 3 real client/server chunk-codec interop bugs, caught by a new golden-fixture test

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No test ever exercised the client ChunkDataDecoder against real byte data
before this (M2 chunk streaming was never fed real content on PC2/PC3).
Added scripts/smoke_test_chunk_codec_interop.gd, decoding the backend's
exact golden fixtures (backend/tests/fixtures/chunks/*.bin) and asserting
byte-identical logical values -- the real cross-language contract this
whole persistence system depends on. It found three bugs on first run:

1. chunk_data_decoder.gd's _read_float32/_write_float32 used `bits as
   float`/`val as int`, a numeric cast in GDScript, not an IEEE-754
   bitcast -- silently corrupted every non-integer position/rotation/
   scale/bounds value (1.5 decoded as 1069547520.0, verified). Fixed with
   PackedByteArray.decode_float/encode_float (real bitcast, same
   little-endian order as the rest of this format).

2. backend/app/services/chunk_codec.py's binary codec wrote bounds as
   min+size, disagreeing with world.md §3's documented min+max wire
   format and with the client's actual (correct) decoder -- corrupted
   every chunk's bounds on the wire despite the backend's own JSON path
   using min+max correctly. Fixed the binary encode/decode to match the
   spec; regenerated the golden fixtures.

3. chunk_data_decoder.gd's object-properties parsing used
   `JSON.parse_string(props_str) or {}` -- GDScript's `or` is a boolean
   operator, not Python/JS-style short-circuit-return, so this silently
   evaluated to a bool for any object with real property data, crashing
   on assignment to the typed `properties: Dictionary` field. Fixed with
   an explicit type check.

Full backend suite (132/132) and 4 sibling client smoke tests re-verified
clean after all three fixes; no other `or {}`/`or []` instances of bug 3's
pattern found elsewhere in the codebase.

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This commit is contained in:

daddy

2026-09-14 19:56:44 +00:00

parent 9c086a4b10

commit eb39e4393d

5 changed files with 139 additions and 13 deletions

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backend/tests/fixtures/chunks/chunk_with_objects.bin

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backend/tests/fixtures/chunks/simple_tile_chunk.bin

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