feat(S9/S8): bank-generation change-detection + instrument-side assignment reader

Extension stamps a monotonic bank_generation counter, bumped at content
mutations; the VST3 instrument polls it off-thread on an editor timer and
consumes assignment requests, refreshing playback hands-free.

CMakeLists.txt

@@ -685,6 +685,17 @@ add_library(waveform_view STATIC src/vst/waveform_view.cpp)
 target_include_directories(waveform_view PUBLIC src/vst src)
 target_link_libraries(waveform_view PUBLIC editor_geometry peaks)
 
+# bank_sync (Phase S9/S8 reader) — PURE decision logic for the instrument's off-audio-thread
+# poll: parse/compare the S9 bank-generation stamp, and the S8 assignment-request CONSUME
+# decision (new-and-resolvable-and-target -> apply; unresolvable -> drop-and-mark; non-target
+# -> stay eligible). The shell owns the timer cadence + side effects (reloadFromBank,
+# setSelectedSampleId, component-state marker); this owns only the yes/no maths, unit-tested
+# outside the DAW. Links assignment_request for the decoded AssignmentRequest it consumes.
+# NEITHER SDK.
+add_library(bank_sync STATIC src/vst/bank_sync.cpp)
+target_include_directories(bank_sync PUBLIC src/vst src)
+target_link_libraries(bank_sync PUBLIC assignment_request)
+
 add_executable(editor_geometry_tests tests/test_editor_geometry.cpp)
 target_link_libraries(editor_geometry_tests PRIVATE editor_geometry)
 add_test(NAME editor_geometry_tests COMMAND editor_geometry_tests)
@@ -718,6 +729,12 @@ add_executable(waveform_view_tests tests/test_waveform_view.cpp)
 target_link_libraries(waveform_view_tests PRIVATE waveform_view)
 add_test(NAME waveform_view_tests COMMAND waveform_view_tests)
 
+# bank_sync (S9/S8 reader): the pure generation-parse + assignment-consume decision. Links
+# ONLY bank_sync (+ its assignment_request dep) — NEITHER SDK — the plain-data-boundary proof.
+add_executable(bank_sync_tests tests/test_bank_sync.cpp)
+target_link_libraries(bank_sync_tests PRIVATE bank_sync)
+add_test(NAME bank_sync_tests COMMAND bank_sync_tests)
+
 # ---------------------------------------------------------------------------
 # 4) The REAPER extension — a loadable module (dlopen'd by REAPER, not linked).
 # ---------------------------------------------------------------------------
@@ -770,7 +787,7 @@ add_library(reaper_reasampler MODULE
     src/card_meta.cpp
     src/card_drag.cpp
 )
-target_link_libraries(reaper_reasampler PRIVATE bank_model capture_paths peaks bank_grid mode_switch tab_strip view_mode_model insert_plan render_settings batch_capture tail_control realtime_record bank_book wav_trim owned_manifest prune_reconcile prune_button app_version provenance action_buttons drag_out theme component_geometry action_bar footer_bar overflow_menu mode_enable tooltip card_meta card_drag assignment_request)
+target_link_libraries(reaper_reasampler PRIVATE bank_model capture_paths peaks bank_grid mode_switch tab_strip view_mode_model insert_plan render_settings batch_capture tail_control realtime_record bank_book wav_trim owned_manifest prune_reconcile prune_button app_version provenance action_buttons drag_out theme component_geometry action_bar footer_bar overflow_menu mode_enable tooltip card_meta card_drag assignment_request bank_sync)
 target_include_directories(reaper_reasampler PRIVATE ${SDK_INC} ${WDL_INC})
 # OUTPUT_NAME is channel-derived (Phase V, V4): "reaper_reasampler" (stable, default) or
 # "reaper_reasampler_beta" (beta). REAPER dlopen's any reaper_* module, so both channels'
@@ -901,9 +918,12 @@ if(WIN32 AND EXISTS "${VST3_SDK}/public.sdk/source/main/pluginfactory.cpp")
     # waveform_view (S11): the pure frame<->pixel marker geometry + zero-crossing snap the
     # editor's waveform surface draws + hit-tests against; links editor_geometry + peaks
     # transitively (shared Rect + AudioSample).
+    # bank_sync (S9/S8 reader): the pure generation-compare + assignment-consume decision the
+    # processor's off-thread poll runs; links assignment_request transitively (the decoded
+    # request it consumes) — the same key the extension writes, shared via the pure module.
     target_link_libraries(reasampler_vst PRIVATE vst3_sdk editor_geometry bridge_marshal
         sample_map capture_paths embed_strip app_version capture_browser keyboard_strip
-        waveform_view)
+        waveform_view bank_sync)
     # SDK_INC gives reaper_vst3_interfaces.h + reaper_plugin_functions.h for the bridge;
     # WDL_INC gives LICE for the editor. The VST3 SDK headers come from vst3_sdk PUBLIC.
     target_include_directories(reasampler_vst PRIVATE ${SDK_INC} ${WDL_INC})