task: Sprint 5 — route audio through in-process plugin for SAFE plugins

Pro-Q 4 spectrum shows no signal because audio goes through Helper instance
while GUI belongs to in-process instance. Fix: call inProcessPlugin->processBlock()
directly in processBlock() when safe plugin is loaded.

Co-Authored-By: Claude Sonnet 4.6 <noreply@anthropic.com>

SYNC.md

@@ -28,7 +28,53 @@ STATUS: no pending questions
 > Read this at the start of every coding session.
 
 ```
-STATUS: no pending messages
+STATUS: TASK READY — Sprint 5
+
+TASK: Route audio through in-process plugin for SAFE plugins (fixes spectrum analyzers)
+
+PROBLEM (verified on Mac 2026-05-17):
+  Pro-Q 4 spectrum analyzer shows no signal inside PluginBridge.
+  Root cause: two separate plugin instances are running —
+    - Helper process instance  → handles audio (but has no GUI)
+    - In-process instance      → provides GUI only (but never sees audio)
+  Pro-Q 4's spectrum belongs to the in-process GUI instance, so it stays empty.
+  The AudioAnalyser MCP tool confirms audio IS flowing (returned live LUFS/FFT data).
+
+FIX — only touch PluginBridgeProcessor.cpp (and .h if needed):
+  In processBlock(), check if a safe in-process plugin is loaded.
+  If yes → call inProcessPlugin->processBlock(buffer, midiMessages) directly.
+  If no (unsafe, Helper-only) → keep existing shm path unchanged.
+
+  Pseudocode:
+    if (inProcessPlugin != nullptr)
+        inProcessPlugin->processBlock(buffer, midiMessages);
+    else
+        // existing shm write → Helper → shm readOutput path
+
+  The in-process plugin is already loaded (loadInProcessPlugin runs for SAFE plugins).
+  You are NOT changing when it loads — only adding the audio call in processBlock.
+
+SCOPE — only these files:
+  TOUCH:    PluginBridgeProcessor.cpp  (processBlock change, ~5 lines)
+            PluginBridgeProcessor.h    (only if inProcessPlugin member needs exposing)
+  DO NOT TOUCH:
+            PluginBridgeEditor.mm      ← LOCKED
+            PluginPickerComponent.mm   ← LOCKED
+            HelperPluginHost.mm        ← LOCKED
+            HelperConnection.cpp       ← LOCKED
+            CMakeLists.txt             ← no new files, no changes needed
+
+VERIFY before pushing:
+  - Does inProcessPlugin->processBlock() exist in JUCE AudioPluginInstance? YES —
+    it inherits from AudioProcessor which has processBlock(AudioBuffer&, MidiBuffer&)
+  - Helper still runs for safe plugins (needed for MCP param read/write via Helper IPC)
+    Do NOT remove the Helper spawn or shm path — just skip the shm audio write when
+    in-process plugin is available.
+  - Do NOT remove PBLOG calls.
+
+EXPECTED RESULT after fix:
+  Pro-Q 4 spectrum analyzer shows live audio. EQ curve interactive.
+  get_analysis MCP tool still works (AudioAnalyser runs on same buffer).
 
 Last (2026-05-17): Sprint 4 regression fixed. PluginBridgeEditor.mm was reverted
 to CALayerHost (FAILED-APPROACHES #10 — never works in Ableton). Restored from