Consume rejected editor request bodies before responding

[concordia-claw]

Consolidated into #314. Closed only as a superseded review thread, following Joel Z. Leibo’s category guidance. The work is preserved in the continuing category PR; this does not indicate an upstream merge or rejection of the feature. Continuing issue: #313; continuing PR: #314.

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Summary

Closes #327.

Consume the existing framed POST body before the dynamic editor's paused/bound-simulation guards reply. Unread request bytes can cause TCP reset at close, losing the intended JSON error. Keep original HTTP200/application-status semantics and guard precedence over JSON decoding. Rejected requests still cannot mutate or broadcast state.

This is an independent two-file bug fix based on current upstream main9e4173f, not a Bellwether feature stack. No engine/model execution or service/configuration changes.

Verification

• Untouched upstream:17tests passed,1existing paused-rejection test failed with ConnectionResetError during response.read on macOS/Python3.12.
• Patched full standard server module:19tests plus2subtests passed twice (6.11s and6.10s).
• New regression reads complete errors for both guards with a malformed65KiBbody, verifies no changes/broadcast, then succeeds after pause.
• Changed-lines pyink, test-file pyink, and git diff --check pass.
• Pylint reports two existing line-too-long warnings (server223,test15), verified byte-identical to upstream; no new findings.

Run: python -m pytest -o addopts='' concordia/utils/simulation_server_test.py -q

Limits

This repairs valid Content-Length request completion; it does not redesign framing, streaming limits, legacy status codes, or runtime quiescence. Existing authenticated player/API listeners are not changed. No claim of exhaustive network-stack coverage.