feat(rta): Context_Switch_Time folded into recurrence (v0.9.2)#198
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feat(rta): Context_Switch_Time folded into recurrence (v0.9.2)#198
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Tier A #5 from the post-v0.9.0 reviewer audit (partial — only Context_Switch_Time; Interrupt_Overhead per ISR firing is the companion follow-up). v0.8.x emitted a STPA-REQ-022 advisory if Context_Switch_Time was unset, but never folded the value into the Tindell-Clark / Joseph-Pandya recurrence when it WAS set — silently optimistic. Now: each thread's WCET is inflated by `2 × Context_Switch_Time` (one preemption-in + one preemption-out per Buttazzo §7) before entering the recurrence. The recurrence math itself (`compute_response_time_jittered_blocking`) is unchanged, so the existing Lean monotonicity / convergence proofs still hold. New `OverheadInflation` Info diagnostic per thread when CS > 0. Default unset = 0 → byte-identical to v0.8.x / v0.9.1. REQ-RTA-008 + TEST-RTA-CONTEXT-SWITCH. 2 new RTA tests (context_switch_inflates_wcet, no_context_switch_byte_identical_to_v091). Co-Authored-By: Claude Opus 4.7 (1M context) <noreply@anthropic.com>
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Tier A #5 partial — folds Context_Switch_Time into the RTA recurrence as 2·CS WCET inflation per Buttazzo §7. v0.8.x warned about CS being unset but didn't use it when set. New OverheadInflation Info diagnostic. Default unset = byte-identical. Lean recurrence theorem unchanged (caller-side inflation).
Test plan: 2 new tests (with-CS / without-CS); workspace tests pass; clippy/fmt/rivet clean.
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