fix: use in-process flag instead of existsSync for cache availability

In OpenCode plugin sandbox, existsSync fails across different hook
contexts (config vs chat.message) because each runs in an isolated
virtual filesystem. Add writtenInCurrentProcess flags to track cache
writes at the process level, eliminating spurious Model Cache Not
Found toast warnings.

Closes #3412

src/shared/connected-providers-cache.ts

@@ -2,6 +2,10 @@ import { log } from "./logger"
 import * as dataPath from "./data-path"
 import { createJsonFileCacheStore } from "./json-file-cache-store"
 
+// Track if provider models cache has been successfully written in the current process
+// This helps in sandbox environments where filesystem state may not persist across contexts
+let providerModelsCacheWrittenInCurrentProcess = false
+
 const CONNECTED_PROVIDERS_CACHE_FILE = "connected-providers.json"
 const PROVIDER_MODELS_CACHE_FILE = "provider-models.json"
 
@@ -84,6 +88,12 @@ export function createConnectedProvidersCacheStore(
 	}
 
 	function hasProviderModelsCache(): boolean {
+		// First check if we've written the cache in the current process
+		// This handles sandbox environments where filesystem state may not persist across contexts
+		if (providerModelsCacheWrittenInCurrentProcess) {
+			return true
+		}
+		// Fall back to the store's has() method (which also checks in-memory state)
 		return providerModelsCacheStore.has()
 	}
 
@@ -92,6 +102,7 @@ export function createConnectedProvidersCacheStore(
 			...data,
 			updatedAt: new Date().toISOString(),
 		})
+		providerModelsCacheWrittenInCurrentProcess = true
 	}
 
 	async function updateConnectedProvidersCache(client: {
@@ -161,6 +172,7 @@ export function createConnectedProvidersCacheStore(
 	function _resetMemCacheForTesting(): void {
 		connectedProvidersCacheStore.resetMemory()
 		providerModelsCacheStore.resetMemory()
+		providerModelsCacheWrittenInCurrentProcess = false
 	}
 
 	return {

src/shared/json-file-cache-store.ts

@@ -27,6 +27,7 @@ export function createJsonFileCacheStore<TValue>(
 	options: JsonFileCacheStoreOptions<TValue>,
 ): JsonFileCacheStore<TValue> {
 	let memoryValue: TValue | null | undefined
+	let writtenInCurrentProcess = false
 
 	function getCacheFilePath(): string {
 		return join(options.getCacheDir(), options.filename)
@@ -67,6 +68,17 @@ export function createJsonFileCacheStore<TValue>(
 	}
 
 	function has(): boolean {
+		// First check if we have a valid in-memory cache value
+		// This handles sandbox environments where existsSync may fail across contexts
+		if (memoryValue !== undefined && memoryValue !== null) {
+			return true
+		}
+		// Check if we've written to this cache in the current process
+		// This helps in sandbox environments where filesystem state may not persist across contexts
+		if (writtenInCurrentProcess) {
+			return true
+		}
+		// Fall back to filesystem check
 		return existsSync(getCacheFilePath())
 	}
 
@@ -77,6 +89,7 @@ export function createJsonFileCacheStore<TValue>(
 		try {
 			writeFileSync(cacheFile, options.serialize?.(value) ?? JSON.stringify(value, null, 2))
 			memoryValue = value
+			writtenInCurrentProcess = true
 			log(`[${options.logPrefix}] ${options.cacheLabel} written`, options.describe(value))
 		} catch (error) {
 			log(`[${options.logPrefix}] Error writing ${toLogLabel(options.cacheLabel)}`, {
@@ -87,6 +100,7 @@ export function createJsonFileCacheStore<TValue>(
 
 	function resetMemory(): void {
 		memoryValue = undefined
+		writtenInCurrentProcess = false
 	}
 
 	return {