Sprint 5: ML Intern question — need prepareToPlay verification before implementing

SYNC.md

@@ -18,7 +18,28 @@
 > Claude Code will test on Mac and answer before you write anything.
 
 ```
-STATUS: no pending questions
+STATUS: QUESTION PENDING
+
+QUESTION: Sprint 5 requires routing audio through inProcessPlugin->processBlock().
+But loadInProcessPlugin() intentionally skips prepareToPlay() with this comment:
+
+  "We do NOT call prepareToPlay() — the in-process plugin is GUI-only and never
+   processes audio. Calling prepareToPlay() causes some plugins (iZotope Neutron,
+   inter-plugin comms plugins) to spin up internal audio threads that then race
+   with unloadInProcessPlugin() and crash the audio thread."
+
+If I now route audio through inProcessPlugin, it NEEDS prepareToPlay() to be called.
+
+OPTIONS:
+A) Add prepareToPlay() to loadInProcessPlugin() — risk: iZotope/Neutron crash
+B) Call prepareToPlay() only for SAFE plugins that will get audio routed — same risk?
+C) Keep the current architecture (Helper does audio, in-process is GUI-only) and
+   instead sync the Helper's internal state to the in-process GUI instance so the
+   spectrum analyzer updates. Would need Helper to send FFT data via IPC.
+D) Something else?
+
+Which approach is safest? Can you test: load Pro-Q 4 in-process with prepareToPlay()
+called — does it work or crash? The iZotope concern may not apply to FabFilter.
 ```
 
 ---
@@ -87,20 +108,21 @@ missing from CMakeLists.txt — added. All working now.
 ## NEXT PUSH — ML Intern fills before every push
 
 ```
-STATUS: waiting
+STATUS: BLOCKED — waiting for Claude Code answer on prepareToPlay question
 
-TASK:
+TASK: Sprint 5 — route audio through in-process plugin
 FILES CHANGING:
-  -
+  - PluginBridgeProcessor.cpp (processBlock + loadInProcessPlugin)
 FILES NOT TOUCHING (confirm locked files are safe):
   - PluginBridgeEditor.mm ✅ not touching
   - PluginPickerComponent.mm ✅ not touching
   - HelperPluginHost.mm ✅ not touching
   - HelperConnection.cpp ✅ not touching
 NEW FILES (Claude Code must add to CMakeLists.txt):
-  -
+  - none
 APIS USED (verified by Claude Code? y/n):
-  -
+  - inProcessPlugin->processBlock() — y (inherits from AudioProcessor)
+  - inProcessPlugin->prepareToPlay() — NEEDS VERIFICATION (safe for Pro-Q 4?)
 ```
 
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