Clean up

docs/PHASE_6_BACKGROUND_PERSISTENCE_DESIGN.md

@@ -23,7 +23,7 @@ Current persistence footholds:
 
 Synchronous persistence is a poor fit for live software. A mutation that changes state should not also have to block on filesystem timing, antivirus scans, slow disks, or transient IO failures. The app needs persistence to be reliable and observable, but not timing-sensitive.
 
-The resilience review calls this out because `SavePersistentState()` style behavior can create unnecessary stalls and makes recovery harder to reason about.
+The resilience review calls this out because synchronous save-after-mutate behavior can create unnecessary stalls and makes recovery harder to reason about.
 
 Phase 6 should turn persistence into:
 
@@ -209,8 +209,8 @@ Current implementation:
 
 - `RuntimeStore::BuildRuntimeStatePersistenceSnapshot(...)` captures serialized runtime-state content and target path.
 - `PersistenceWriter::WriteSnapshot(...)` owns the temp-file and replace write mechanics.
-- `RuntimeStore::SavePersistentState(...)` still behaves synchronously, but now writes through `PersistenceWriter`.
-- Stack preset saves also use `PersistenceWriter` synchronously; preset async policy remains a later decision.
+- Runtime-state persistence now flows through `RuntimeStore::RequestPersistence(...)` and the background writer.
+- Stack preset saves still use `PersistenceWriter` synchronously; preset async policy remains a later decision.
 
 ### Step 3. Add Debounced Background Worker
 
@@ -226,7 +226,7 @@ Current implementation:
 
 - `PersistenceWriter::EnqueueSnapshot(...)` starts a worker lazily and debounces snapshots by `debounceKey`.
 - Runtime-state saves enqueue debounced snapshots, so routine mutation paths no longer write the runtime-state file directly.
-- Synchronous `PersistenceWriter::WriteSnapshot(...)` remains for stack preset saves and transitional direct writes.
+- Synchronous `PersistenceWriter::WriteSnapshot(...)` remains for stack preset saves.
 - `PersistenceWriterTests` use an injected in-memory sink to verify coalescing and non-coalesced immediate requests without touching the filesystem.
 
 ### Step 4. Add Atomic Write And Failure Reporting