rewrite(phase8): batch A — content-parity audit (record/observe/config/cli + dyndata/redundancy/sim re-verify)

[SoundMatt]

rewrite(phase8): batch A — content-parity audit (record/observe/config/cli + dyndata/redundancy/sim re-verify)

Part of the v3.0.0 ground-up rewrite (cpp-RCP #129, ROADMAP.md Phase 17),
branch rewrite/v3-from-c-rcp. Phase 8 (remaining modules), batch A of 2:
record, observe, config, cli -- all already implemented+tested from an
earlier untracked pass; audited against c-RCP for genuine capability
gaps. Plus dyndata/redundancy/sim (no c-RCP equivalent) re-verified for
integration/staleness against the now much more mature Phase 5-7 core.

record.hpp vs c-RCP recorder.c/recorder.h

No functional gaps -- both sides deliberately diverge to different
capture granularities (c-RCP: raw ACF/AVTPDU frames; cpp-RCP: RC-Client
request/response pairs), already documented on both sides. Closed 5
real test gaps instead: write_binary()/read_binary() failure paths,
mutation-immunity of stored entries, Playback::run_all()'s actual-sleep
branch (previously only exercised at speed_factor=0.0), PlaybackConfig{}
default.

observe.hpp: genuine gaps ported

• New standalone observe::record() free function (mirrors c-RCP's
  rcp_observe_record()) -- lets a caller record a span/counters
  directly without an ObservingClient wrapper; ObservingClient::request()
  now delegates to it.
• Span::stream_key added (previously byte_bus_id only, unlike c-RCP's
  full addr).
• Metric/MetricsSink::record_counter gained byte_bus_id (previously
  stream_key only, losing per-endpoint attribution within a stream).
  7 new tests added.

config.hpp: largest gap, includes a real latent bug fix

c-RCP's config.c had a later rework (server/hw_pin_map schema feeding
mock.c) cpp-RCP never picked up. Ported the two pieces reachable
without touching mock.hpp (out of scope): ServerManifest +
apply_to_mock() with c-RCP's exact merge semantics (magic overwritten
only if nonzero, options OR'd not overwritten), HwPinManifestEntry +
capacity-checked application to RegisterMap::hw_pin_map, load_to_mock()
combinator. NOT ported (documented, deliberate): c-RCP's dynamic
endpoints/streams sections -- mock::Server has no dynamic
endpoint-registration API, fixed at compile time.

Real bug fixed: the endpoint-entry parser only routed an object to
parse_endpoint_entry if BOTH stream_key and byte_bus_id keys were
present in the raw scan -- an entry with only one was silently
DROPPED rather than rejected. The same bug class c-RCP's own config.c
independently found and fixed (per its own 2026-08-13/#338 comment).
Fixed by routing on EITHER key, with parse_endpoint_entry itself now
the one place that validates both are genuinely present (throwing
ParseError if not) -- a malformed entry is now loudly rejected, not
silently dropped. 15 new tests added.

cli.hpp: genuine gaps ported

• capabilities_json()'s features array now reports the 5 REQ-RMAP-030
  option names (time_sync/enhanced_cancel/trigger/chained/
  compound_bundles) -- cpp-RCP has real underlying implementations for
  all 5 but never advertised them.
• transports now includes "tsn" (a real, non-stub wrapper), matching
  c-RCP's own equivalent module.
  5 new tests added (previously-untested help/--help/-h dispatch, dangling
  --format value, status default text, new capabilities fields).

dyndata.hpp / redundancy.hpp / sim.hpp (no c-RCP equivalent)

Confirmed clean, no changes: every call site verified to match current
lifecycle.hpp/e2e.hpp/regmap.hpp/watchdog.hpp/adapt.hpp/mock.hpp shapes
exactly; test coverage confirmed real (genuine construction, real
state-transition assertions, meaningful concurrency stress, real
mock::Server/Adapt() integration), not vestigial.

Catalog flags, correctly left untouched (Phase 6 is closed)

• REQ-REC-006/007, REQ-OBS-009..022, REQ-CFG-007..020, REQ-CLI-005/006:
  various no-cpp-counterpart or cross-language content-mismatch ids.
• REQ-RED-001/002/003: catalog titles still say "RedundantController"
  (the retired class name) though text/code/tests correctly say
  RedundantRequestFn -- a catalog-only staleness artifact.

Verification

Independently re-verified: confirmed the config.hpp routing fix
directly against source -- the "else if" now reads
obj.find("stream_key") != npos || obj.find("byte_bus_id") != npos
(was implicitly AND-gated before), and parse_endpoint_entry itself
throws ParseError if byte_bus_id is missing -- exactly the claimed
fix. Confirmed the REQ-RED-* title-staleness claim directly against
.fusa-reqs.json (titles say "RedundantController", code/tests say
"RedundantRequestFn" 12/13 times respectively). Full tree rebuilt from
scratch: 0 errors, 0 warnings, 58/58 ctest suites pass (100%).

include/rcp/cli.hpp: +28 (619->647). include/rcp/config.hpp: +267
(172->439). include/rcp/observe.hpp: +43 (168->211). include/rcp/
record.hpp, dyndata.hpp, redundancy.hpp, sim.hpp: unchanged.
tests/test_cli.cpp: +37. tests/test_config.cpp: +156.
tests/test_observe.cpp: +144. tests/test_record.cpp: +85.

Co-Authored-By: Claude Sonnet 5 noreply@anthropic.com