[TomCC7]

Generated message ports previously fell through to pickle because generated classes do not expose lcm_encode. The default factory now selects registry-owned CDR on the configured LCM or Zenoh backend. The existing Python → C++ → Rust → Python example uses ordinary coordinator wiring without manual transport maps. Sensor QoS recognizes canonical names, with never-drop channel precedence retained.

Linear: https://linear.app/dimensional/project/message-encoding-refactor-05a3ddb4af3e/overview

Parent: #4695. This is the default generated-port boundary cutover; legacy typed ports and Python-object channels retain their distinct paths. No wire negotiation or old-recording fallback. Full graph/recorder/fixture acceptance and eventual legacy dependency retirement remain separate open gates.

Category	Files	Additions	Deletions
Factory and CDR documentation	2	26	7
Factory regression tests	1	40	0
Exact three-language example	1	16	35
CI definitions	1	2	2

Manual local smoke (after installing this proposal checkout and its test dependencies):

LCM_DEFAULT_URL=memq:// python -m pytest --noconftest -o addopts='' -q dimos/core/test_transport_factory.py dimos/core/test_cdr_transport.py

The external example's existing CMake/Cargo build instructions remain in docs/development/messages-external-project.md; after building, from that external project:

python demo_modules.py --cpp build/cpp/telemetry_module --rust modules/target/debug/telemetry_module

Expected: PASS: coordinator Python -> C++ -> Rust -> Python over loopback Zenoh CDR. Manual execution requires an interactive terminal; decline optional host setup. No robot is used.

Validation: 37 source tests and 37 isolated installed-wheel tests passed (production modules preloaded from site-packages), two production files passed strict mypy, configured scoped hooks passed except unavailable Nix lint. Actual installed SDK example compiled C++/Rust and completed the default-factory coordinator exchange, including exact shared Header identity and the noninteractive manual refusal test. Main wheel built: SHA256 bbbe0c8d54a2b045d7993ff653f01ed07dd0cb24c3f8edcd355bf53c860c6044. First two native acceptance attempts exposed local CMake/pkg-config invocation omissions; corrected cached dependency paths passed. No CI polling, benchmark, hardware, or publication to a package registry.