Add a queue to shmrpc

[Dreamsorcerer]

I'm not entirely sure if it might be more appropriate to use this everywhere for SHM or not. But, for RPC atleast, this fixes the concurrency tests.

[greptile-apps]

Greptile Summary

This PR adds a queued shared-memory path for RPC messages. The main changes are:

• Adds CpuShmQueue as a ring-buffer channel implementation.
• Lets shared-memory pubsub choose a channel class and layout options per subclass.
• Switches ShmRPC to the queued channel with a smaller per-message capacity.
• Adds queue-focused IPC tests and re-enables shared-memory RPC concurrency coverage.

Confidence Score: 5/5

This looks safe to merge.

• No blocking issues found in the changed code.

Important Files Changed

Filename	Overview
dimos/protocol/pubsub/impl/shmpubsub.py	Adds channel-class selection and layout-based shared-memory naming for pubsub topics.
dimos/protocol/pubsub/shm/ipc_factory.py	Adds the queued CPU shared-memory channel with ring slots, per-segment ownership, publish/read logic, and close handling.
dimos/protocol/rpc/pubsubrpc.py	Configures ShmRPC to use the queued shared-memory channel with fixed capacity and slot count.
dimos/protocol/pubsub/shm/test_ipc_factory.py	Adds tests for queue delivery, wraparound, attach behavior, and layout mismatch handling.
dimos/protocol/rpc/test_spec.py	Expands async RPC coverage across implementations and runs shared-memory concurrent-call tests.

_{Reviews (4): Last reviewed commit: "Add assert" | Re-trigger Greptile}

[codecov]

Codecov Report

❌ Patch coverage is 93.07692% with 18 lines in your changes missing coverage. Please review.
✅ All tests successful. No failed tests found.

Files with missing lines	Patch %	Lines
dimos/protocol/pubsub/shm/ipc_factory.py	86.66%	11 Missing and 7 partials ⚠️

@@            Coverage Diff             @@
##             main    #2717      +/-   ##
==========================================
+ Coverage   72.35%   72.41%   +0.05%     
==========================================
  Files         902      903       +1     
  Lines       81820    82064     +244     
  Branches     7396     7451      +55     
==========================================
+ Hits        59201    59423     +222     
- Misses      20639    20649      +10     
- Partials     1980     1992      +12     

Flag	Coverage Δ
OS-ubuntu-24.04-arm	64.63% <93.07%> (+0.09%)	⬆️
OS-ubuntu-latest	67.26% <93.07%> (+0.07%)	⬆️
Py-3.10	67.24% <93.07%> (+0.06%)	⬆️
Py-3.11	67.25% <93.07%> (+0.07%)	⬆️
Py-3.12	67.24% <93.07%> (+0.07%)	⬆️
Py-3.13	67.25% <93.07%> (+0.07%)	⬆️
Py-3.14	67.27% <93.07%> (+0.08%)	⬆️
Py-3.14t	67.25% <93.07%> (+0.07%)	⬆️
SelfHosted-Large	30.19% <21.92%> (-0.03%)	⬇️
SelfHosted-Linux	37.99% <24.61%> (-0.06%)	⬇️
SelfHosted-macOS	36.32% <21.92%> (-0.05%)	⬇️

Flags with carried forward coverage won't be shown. Click here to find out more.

Files with missing lines	Coverage Δ
dimos/protocol/pubsub/impl/shmpubsub.py	75.26% <100.00%> (+0.40%)	⬆️
dimos/protocol/pubsub/shm/test_ipc_factory.py	100.00% <100.00%> (ø)
dimos/protocol/rpc/pubsubrpc.py	88.11% <100.00%> (-0.15%)	⬇️
dimos/protocol/rpc/test_spec.py	95.06% <100.00%> (-0.03%)	⬇️
dimos/protocol/pubsub/shm/ipc_factory.py	73.79% <86.66%> (+9.37%)	⬆️

... and 4 files with indirect coverage changes

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