fix(renderer): release retired store snapshots from selector caches (#23187)

Co-authored-by: m4air <m4air@m4airs-Air.localdomain>

src/renderer/src/components/right-sidebar/parent-pr-checks-projection-selector.test.ts

@@ -56,6 +56,39 @@ function review(number: number): HostedReviewInfo {
 }
 
 describe('parent PR checks projection selector', () => {
+  it.each([false, true])(
+    'releases unrelated store data while keeping the projection cached (replacement=%s)',
+    async (replacement) => {
+      if (typeof globalThis.gc !== 'function') {
+        throw new Error('Run with the repository Vitest --expose-gc config')
+      }
+      const select = createParentPrChecksProjectionSelector({
+        worktrees: [worktree(0)],
+        repos: [repo()],
+        settings: null,
+        refreshOutcomes: new Map()
+      })
+      if (replacement) {
+        select({ hostedReviewCache: {}, prCache: {}, checksCache: {} })
+      }
+      const caches = { hostedReviewCache: {}, prCache: {}, checksCache: {} }
+      function selectRetiredState(): WeakRef<object> {
+        const unrelatedData = { content: new Uint8Array(1024 * 1024) }
+        const state = { ...caches, unrelatedData }
+        select(state)
+        return new WeakRef(unrelatedData)
+      }
+      const retired = selectRetiredState()
+      const projection = select(caches)
+      for (let round = 0; round < 3; round++) {
+        await new Promise<void>((resolve) => setImmediate(resolve))
+        globalThis.gc()
+      }
+      expect(retired.deref()).toBeUndefined()
+      expect(select(caches)).toBe(projection)
+    }
+  )
+
   it('does not inspect tracked keys when cache map references are unchanged', () => {
     const cacheRead = vi.fn()
     const observedCache = new Proxy(

src/renderer/src/components/right-sidebar/parent-pr-checks-projection-selector.ts

@@ -18,6 +18,15 @@ type CacheDependency = {
   value: unknown
 }
 
+function selectCacheReferences(state: ReviewCacheState): ReviewCacheState {
+  // Pick narrows the type, not the object received from the store.
+  return {
+    hostedReviewCache: state.hostedReviewCache,
+    prCache: state.prCache,
+    checksCache: state.checksCache
+  }
+}
+
 function trackCacheReads<K extends ReviewCacheName>(
   state: ReviewCacheState,
   cacheName: K,
@@ -74,7 +83,7 @@ export function createParentPrChecksProjectionSelector(
       }
       if (dependenciesAreCurrent(state, cached.cacheReferences, cached.dependencies)) {
         // Why: adopting unrelated replacement maps keeps later store notifications O(1).
-        cached.cacheReferences = state
+        cached.cacheReferences = selectCacheReferences(state)
         return cached.projection
       }
     }
@@ -88,7 +97,7 @@ export function createParentPrChecksProjectionSelector(
       prCache: trackCacheReads(state, 'prCache', dependencies),
       checksCache: trackCacheReads(state, 'checksCache', dependencies)
     })
-    cached = { cacheReferences: state, dependencies, projection }
+    cached = { cacheReferences: selectCacheReferences(state), dependencies, projection }
     return projection
   }
 }

src/renderer/src/components/terminal-pane/terminal-pane-host-state-memo.test.ts

@@ -54,6 +54,23 @@ beforeEach(() => {
 })
 
 describe('selectTerminalPaneHostState memo', () => {
+  it('releases the last store snapshot when no terminal selects again', async () => {
+    if (typeof globalThis.gc !== 'function') {
+      throw new Error('Run with the repository Vitest --expose-gc config')
+    }
+    function selectRetiredState(): WeakRef<AppState> {
+      const state = makeState()
+      selectTerminalPaneHostState(state, LOCAL_WORKTREE)
+      return new WeakRef(state)
+    }
+    const retired = selectRetiredState()
+    for (let round = 0; round < 3; round++) {
+      await new Promise<void>((resolve) => setImmediate(resolve))
+      globalThis.gc()
+    }
+    expect(retired.deref()).toBeUndefined()
+  })
+
   it('returns the same object across an unrelated store write', () => {
     const first = makeState()
     const before = selectTerminalPaneHostState(first, LOCAL_WORKTREE)

src/renderer/src/components/terminal-pane/terminal-pane-host-state.ts

@@ -78,7 +78,8 @@ function isSameHostState(a: TerminalPaneHostState, b: TerminalPaneHostState): bo
   )
 }
 
-let cachedState: AppState | null = null
+// Identity checks must not keep a retired store alive after the last pane unmounts.
+let cachedState: WeakRef<AppState> | null = null
 let cachedByWorktreeId = new Map<string, TerminalPaneHostState>()
 let previousByWorktreeId = new Map<string, TerminalPaneHostState>()
 
@@ -100,10 +101,10 @@ export function selectTerminalPaneHostState(
   state: AppState,
   worktreeId: string
 ): TerminalPaneHostState {
-  if (state !== cachedState) {
+  if (state !== cachedState?.deref()) {
     previousByWorktreeId = cachedByWorktreeId
     cachedByWorktreeId = new Map()
-    cachedState = state
+    cachedState = new WeakRef(state)
   }
   const cached = cachedByWorktreeId.get(worktreeId)
   if (cached) {