policy_client: producer + hardware-registry integration

[shantanuparab-tr]

Summary

Wires PolicyClient into the SDK runtime: a PolicyClientProducer (so the chunk-aligned command stream is a recordable source), registry placement so it constructs from config, and the small arm change the playback path needs.

Stack: PolicyClient stack, based on #248. Review bottom-up (#253 → here). This PR touches ArmConfig/TrossenArmComponent, which #248 also changes — see Related.

Changes

• In include/trossen_sdk/hw/policy/policy_client_producer.{hpp} + src/hw/policy/policy_client_producer.cpp: PolicyClientProducer emitting the commanded rows (with joint_names in the stream metadata/features); REGISTER_PRODUCER / REGISTER_HARDWARE under "policy_client".
• In include/trossen_sdk/hw/active_hardware_registry.hpp + src/hw/active_hardware_registry.cpp: registry placement so a policy_client hardware entry is constructed and configured from JSON.
• In include/trossen_sdk/configuration/types/producers/producer_config.hpp: carry the policy-client producer config.
• In include/trossen_sdk/configuration/types/hardware/arm_config.hpp + include/trossen_sdk/hw/arm/trossen_arm_component.{hpp,cpp}: add write_moving_time_s — the per-tick trajectory time passed to set_all_positions() in write_joint() (0 = apply immediately; non-zero smooths per-tick motion, on top of the Face EMA). Reconciled with control: per-episode hardware lifecycle driven by SessionManager #248's arm changes: built on control: per-episode hardware lifecycle driven by SessionManager #248's slew_time_s/staged_position/episode_lifecycle_enabled, adding only write_moving_time_s.
• In tests/test_policy_client_producer.cpp, tests/test_active_hardware_registry.cpp, tests/CMakeLists.txt: producer metadata + registry construction coverage.
• In cmake/policy_client.cmake: add policy_client_producer.cpp to the gated sources.

Test Plan

• Builds cleanly with -DTROSSEN_SDK_ENABLE_POLICY_CLIENT=ON
• Tests pass — test_policy_client_producer, test_active_hardware_registry, test_config
• Lint passes (pre-commit run --all-files)
• Hardware — exercised end-to-end via the live pi05 integration (see policy_client: stationary examples (openpi + lerobot) #255)

Breaking Changes

None. write_moving_time_s is optional (defaults to 0.0 = previous behavior). New gated sources behind TROSSEN_SDK_ENABLE_POLICY_CLIENT (default OFF).

Related

Based on #248. Depends on #248's ArmConfig rework — this PR's arm change is reconciled on top of slew_time_s/staging (adds only write_moving_time_s), so it must merge after #248. Stacked on #253; followed by #255.

[shantanuparab-tr]

Warning

This pull request is not mergeable via GitHub because a downstack PR is open. Once all requirements are satisfied, merge this PR as a stack on Graphite.
Learn more

• policy_client: stationary examples (openpi + lerobot) #255
• policy_client: producer + hardware-registry integration #254 👈 (View in Graphite)
• policy_client: PolicyClient bridge, Face adapters, inference loop #253
• policy_client: transport interface, registry, and both transports #252
• policy_client: wire-format codecs (openpi msgpack + lerobot pickle) #251
• policy_client: neutral observation/action types #250
• policy_client: config schema + SdkConfig wiring #249
• control: per-episode hardware lifecycle driven by SessionManager #248
• main

This stack of pull requests is managed by Graphite. Learn more about stacking.