From 05af0e92ef74c975fd61afe1ecaeff2b395412a7 Mon Sep 17 00:00:00 2001
From: Neil <4138956+nwparker@users.noreply.github.com>
Date: Sun, 24 May 2026 13:03:41 -0700
Subject: [PATCH] Fix WSL preflight context snapshot stability (#2749)

---
 .../src/lib/local-preflight-context.test.ts   | 89 +++++++++++++++++++
 .../src/lib/local-preflight-context.ts        | 17 +++-
 2 files changed, 105 insertions(+), 1 deletion(-)
 create mode 100644 src/renderer/src/lib/local-preflight-context.test.ts

diff --git a/src/renderer/src/lib/local-preflight-context.test.ts b/src/renderer/src/lib/local-preflight-context.test.ts
new file mode 100644
index 00000000000..1c036f8d530
--- /dev/null
+++ b/src/renderer/src/lib/local-preflight-context.test.ts
@@ -0,0 +1,89 @@
+import { describe, expect, it } from 'vitest'
+import type { AppState } from '@/store/types'
+import {
+  getLocalPreflightContext,
+  getWslDistroFromPath,
+  localPreflightContextKey
+} from './local-preflight-context'
+
+function makeState(args: { repoPath?: string | null; worktreePath?: string | null }): AppState {
+  const repoId = 'repo-1'
+  const worktreeId = `${repoId}::worktree-1`
+  return {
+    activeRepoId: repoId,
+    activeWorktreeId: args.worktreePath === undefined ? null : worktreeId,
+    repos:
+      args.repoPath === undefined
+        ? []
+        : [
+            {
+              id: repoId,
+              path: args.repoPath
+            }
+          ],
+    worktreesByRepo:
+      args.worktreePath === undefined
+        ? {}
+        : {
+            [repoId]: [
+              {
+                id: worktreeId,
+                repoId,
+                path: args.worktreePath
+              }
+            ]
+          }
+  } as AppState
+}
+
+describe('local preflight context', () => {
+  it('extracts WSL distro names from supported UNC forms', () => {
+    expect(getWslDistroFromPath(String.raw`\\wsl.localhost\Ubuntu\home\alice\repo`)).toBe('Ubuntu')
+    expect(getWslDistroFromPath(String.raw`\\wsl$\Debian\home\alice\repo`)).toBe('Debian')
+    expect(getWslDistroFromPath('/Users/alice/repo')).toBeNull()
+  })
+
+  it('returns a stable snapshot for repeated WSL selector reads', () => {
+    const state = makeState({
+      worktreePath: String.raw`\\wsl.localhost\Ubuntu\home\alice\repo`
+    })
+
+    const first = getLocalPreflightContext(state)
+    const second = getLocalPreflightContext(state)
+
+    expect(first).toBe(second)
+    expect(first).toEqual({ wslDistro: 'Ubuntu' })
+    expect(localPreflightContextKey(first)).toBe('wsl:Ubuntu')
+  })
+
+  it('reuses the same WSL snapshot across equivalent active repo and worktree paths', () => {
+    const fromRepo = getLocalPreflightContext(
+      makeState({
+        repoPath: String.raw`\\wsl.localhost\Ubuntu\home\alice\repo`
+      })
+    )
+    const fromWorktree = getLocalPreflightContext(
+      makeState({
+        repoPath: '/Users/alice/repo',
+        worktreePath: String.raw`\\wsl.localhost\Ubuntu\home\alice\repo`
+      })
+    )
+    const fromOtherDistro = getLocalPreflightContext(
+      makeState({
+        worktreePath: String.raw`\\wsl.localhost\Debian\home\alice\repo`
+      })
+    )
+
+    expect(fromRepo).toBe(fromWorktree)
+    expect(fromOtherDistro).not.toBe(fromRepo)
+    expect(fromOtherDistro).toEqual({ wslDistro: 'Debian' })
+  })
+
+  it('uses the stable host context for non-WSL paths', () => {
+    const state = makeState({ repoPath: '/Users/alice/repo' })
+
+    expect(getLocalPreflightContext(state)).toBeUndefined()
+    expect(getLocalPreflightContext(state)).toBeUndefined()
+    expect(localPreflightContextKey(getLocalPreflightContext(state))).toBe('host')
+  })
+})
diff --git a/src/renderer/src/lib/local-preflight-context.ts b/src/renderer/src/lib/local-preflight-context.ts
index 1c0cf887e23..7f17191e680 100644
--- a/src/renderer/src/lib/local-preflight-context.ts
+++ b/src/renderer/src/lib/local-preflight-context.ts
@@ -3,10 +3,25 @@ import { parseWslUncPath } from '../../../shared/wsl-paths'
 
 export type LocalPreflightContext = { wslDistro?: string | null } | undefined
 
+const wslPreflightContextsByDistro = new Map<string, NonNullable<LocalPreflightContext>>()
+
 export function getWslDistroFromPath(path?: string | null): string | null {
   return path ? (parseWslUncPath(path)?.distro ?? null) : null
 }
 
+function getWslPreflightContext(wslDistro: string): NonNullable<LocalPreflightContext> {
+  const cached = wslPreflightContextsByDistro.get(wslDistro)
+  if (cached) {
+    return cached
+  }
+
+  // Why: React/Zustand selectors must return a cached snapshot. A fresh object
+  // here triggers a useSyncExternalStore loop when Settings observes WSL repos.
+  const context = Object.freeze({ wslDistro })
+  wslPreflightContextsByDistro.set(wslDistro, context)
+  return context
+}
+
 export function getLocalPreflightContext(state: AppState): LocalPreflightContext {
   const activeWorktree = state.activeWorktreeId
     ? Object.values(state.worktreesByRepo ?? {})
@@ -16,7 +31,7 @@ export function getLocalPreflightContext(state: AppState): LocalPreflightContext
   const activePath =
     activeWorktree?.path ?? (state.repos ?? []).find((repo) => repo.id === state.activeRepoId)?.path
   const wslDistro = getWslDistroFromPath(activePath)
-  return wslDistro ? { wslDistro } : undefined
+  return wslDistro ? getWslPreflightContext(wslDistro) : undefined
 }
 
 export function localPreflightContextKey(context: LocalPreflightContext): string {