Refactor: split trb bind_callable into lifecycle helpers

[ChaoWao]

Summary

The ~200-line bind_callable_to_runtime_impl (trb host side) folded three distinct lifecycles into one function. This splits it into named steps so the entry point reads as the lifecycles it orchestrates:

• resolve_arena_sizing (per-config) — ring sizing + derived heap/SM sizes + scheduler timeout (the layout input half, pure host arithmetic)
• stage_device_args (per-run) — the only signature-aware step: H2D copy / pure-OUTPUT zeroing / copy-back recording
• apply_orch_sched_env_flags (per-run) — latch the orch→sched env gates
• ensure_static_arenas (per-config) — reserve + acquire the static pools
• build_runtime_image (per-config) — pure host image build, no device touch (the hook a later image-cache stage can memoize)
• bind_launch_state (per-run) — publish args + rtMemcpy + record device base

bind_callable_to_runtime_impl collapses to a ~45-line orchestrator.

Behavior is byte-identical: all TIMING: logs, the simpler_run.bind.{args,prebuilt} STRACE spans (consumed by pypto-serving), log ordering, and error paths are preserved. The host DeviceArena stays a caller-owned local passed by reference (it is non-copyable/non-movable), so the image outlives the call until upload.

Also re-syncs the drifted a2a3/a5 copies: a5 adopts the STRACE markers, common/strace.h include, and pto2_-prefixed naming that were pure drift — the two runtime_maker.cpp files are now byte-identical.

This is the host-side function-split groundwork; the device-ABI layout split, static host_api relocation, and register-time image caching are separate follow-up stages.

Testing

• Simulation tests pass — tests/st/{a2a3,a5}/tensormap_and_ringbuffer: a2a3sim 30 passed / 1 skipped, a5sim 20 passed
• Hardware tests (not required: host-only change, behavior byte-identical, sim-verified)

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Review details

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📥 Commits

Reviewing files that changed from the base of the PR and between b0b1976 and f4ba6c9.

📒 Files selected for processing (2)

• src/a2a3/runtime/tensormap_and_ringbuffer/host/runtime_maker.cpp
• src/a5/runtime/tensormap_and_ringbuffer/host/runtime_maker.cpp

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[gemini-code-assist]

Code Review

This pull request refactors bind_callable_to_runtime_impl in both the a2a3 and a5 runtime makers by extracting several modular helper functions to handle arena sizing, device arguments staging, environment flags, static arenas, runtime image building, and launch state binding. Feedback highlights a potential state leakage issue in both implementations where the orch_to_sched flag is set to true if the PTO2_ORCH_TO_SCHED environment variable is truthy, but is never reset to false if the variable is unset or falsy, which could persist incorrect configurations across multiple runs.

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