[SoundMatt]

Summary

Implements ROADMAP.md milestone 50, "E2E CRC Safe Points & Safety-Request Variants (v2.6.0)" — the Phase 13 milestone the roadmap's own introduction names as "the point at which the mandatory baseline plus safe-points exist."

• rcp/e2e.hpp REPLACED in full (per the Satellite Package Disposition table): the pre-replacement CRC-16/CCITT-FALSE + sequence-counter + replay-window wrapper around rcp.hpp's Controller is discarded, not adapted. Nothing else in the tree depended on that old API (only its own test did), so no legacy_e2e.hpp split was needed.
  • crc32 implements the actual TC18 end-to-end CRC (32-bit, polynomial 0xF4ACFB13, init 0xFFFFFFFF, final XOR 0xFFFFFFFF, both input/output reflected) via the standard table-less right-shifting construction.
  • coverage_buffer/compute_crc hash exactly stream_id + avtp_timestamp (zero-filled under NTSCF) + the ACF shared header + payload; apply_acf_length_adjustment/apply_frame_length_adjustment implement the +1 quadlet / +4 octet trailing-CRC length pre-adjustment on top of rcp/wire.hpp's existing codec, unmodified.
  • crc_required gates CRC checking per message role off regmap::EndpointGenericConfig's new ep_req_crc_enable/ep_ack_crc_enable/ep_response_crc_enable toggles; E2eErrc::crc_error is the CRC_ERROR failure path.
  • RxStreamGuard (rx_enforce_e2e drop-vs-latch), RxSequenceGuard (rx_enforce_seq monotonic check), RxWatchdog (rx_wd_enable/rx_wd_timeout_interval overflow + safe-state latch + rx_wd_info_enable).
  • apply_watchdog_overflow/apply_queue_overflow implement the purge-normal/retain-safety queue rule by calling sequencer::RequestLedger::cancel_all(true) directly — reusing v2.5.0's clear-non-safestate mechanism rather than reimplementing it.
  • endpoint_in_configured_safe_state/may_execute_now implement the load-bearing safe-state gate: a safety-tagged request only executes once its endpoint is in its configured safe state.
• rcp/regmap.hpp: RequestStreamConfig expanded from three placeholder fields to the full eleven-field watchdog/safe-state register set (rx_wd_timeout_interval, rx_wd_enable, rx_wd_safestate_enable, rx_enforce_e2e, rx_enforce_seq, rx_seq_safestate_enable, rx_ovrflw_safestate_enable, rx_safety_measure, rx_safestate_sequencer, rx_safe_sequencer_state, rx_wd_info_enable) plus the new RxSafetyMeasure enum; EndpointGenericConfig gains the three CRC toggles.
• rcp/sequencer.hpp: adds the three MSB-set safety-tagged opcodes — CompoundSafety (0x8F), CompoundWaitSafety (0x8B), TriggeredSafety (0x8E) — accepted by decode_request_type and mapped by category_of onto their base opcode's existing priority category; is_safety_variant and the new request_record_for factory give RequestRecord::is_safety a single, automatic source of truth.

New/updated coverage: tests/test_e2e.cpp (REQ-E2E-001..014, entirely rewritten), tests/test_sequencer.cpp (REQ-SEQ-010..012, added), tests/test_regmap.cpp (REQ-REGMAP-009 rewritten for the expanded field set, REQ-REGMAP-015 added), traced in .fusa-reqs.json. Bumps kVersion/project version to 2.6.0. ROADMAP.md gets a **Done (v2.6.0):** summary for milestone 50.

Test plan

All run locally against this branch (AppleClang 21; the repo's alire/gnat g++ 16.1.0 toolchain hits a pre-existing, unrelated sim.hpp build failure reproducible on unmodified main — not something this PR touches or introduces):

• cmake --build build --parallel — full project builds clean
• ctest --test-dir build -j1 — 53/53 tests pass
• cpfusa check — 0 errors
• cpfusa lint — 0 errors (against a clean checkout, matching CI's no-prior-build environment)
• cpfusa cyber — 0 errors
• cpfusa trace --req-coverage 100 — 438/438 requirements annotated and tested (100%/100%)
• cpfusa verify — 53/53 tests pass, evidence generated
• RELAY conformance gate (relay conform --strict build/cpp-rcp) — PASS (§12.1–12.3)