ADFA-5176: Do not build the shared interceptor during Activity construction

HelpActivity and IDETooltipWebViewFragment forced
DocumentationRequestInterceptor.shared from a property initializer, so
the whole lazy ran during construction, before onCreate, on the main
thread. Two consequences.

Environment.DOC_DB is a plain static File with no initializer, assigned
only by Environment.init(). DeviceProtectedApplicationLoader wraps that
call in runCatching and the credential-protected loader returns before
it when storage is not ready, so null is a state the app can really be
in -- and the non-null parameter turned it into an NPE that killed the
activity before it existed. shared is nullable now and declines instead,
which puts the request back on the local web server: the same thing a
null from intercept() already means everywhere else.

The lazy also stats external storage for the nointercept sentinel. On
the main thread that is a disk read under a StrictMode policy built with
detectAll(), and on a contended FUSE mount it stalls the frame that
opens the screen. Touched from shouldInterceptRequest instead, on a
WebView thread, the way FAQActivity already did it.

Not covered here: intercept() still has no throw guard, so an Error
(an OOM decoding a large row) escapes onto a Chromium thread rather
than falling through to the server the way the class documents. That is
a separate finding from the same review.

Found in review of PR #1726.

Author: davidschachterADFA

app/src/main/java/com/itsaky/androidide/activities/editor/FAQActivity.kt

@@ -71,7 +71,7 @@ class FAQActivity : EdgeToEdgeIDEActivity() {
 						view: WebView,
 						request: WebResourceRequest,
 					): WebResourceResponse? =
-						DocumentationRequestInterceptor.shared.intercept(request)
+						DocumentationRequestInterceptor.shared?.intercept(request)
 							?: super.shouldInterceptRequest(view, request)
 				}
 

app/src/main/java/com/itsaky/androidide/fragments/IDETooltipWebViewFragment.kt

@@ -38,7 +38,10 @@ import com.itsaky.androidide.documentation.DocumentationRequestInterceptor
 class IDETooltipWebviewFragment : Fragment() {
 	private lateinit var webView: WebView
 	private lateinit var website : String
-	private val documentation = DocumentationRequestInterceptor.shared
+	// by lazy: an initializer here runs during Fragment construction on the main thread, where the
+	// interceptor's sentinel check is a disk read StrictMode reports and a missing database is a
+	// crash before the view exists. See HelpActivity for the same note.
+	private val documentation by lazy { DocumentationRequestInterceptor.shared }
 
 	//This warning is unnecessary because we control the content
 	@SuppressLint("SetJavaScriptEnabled")
@@ -83,7 +86,7 @@ class IDETooltipWebviewFragment : Fragment() {
 			override fun shouldInterceptRequest(
 				view: WebView,
 				request: WebResourceRequest,
-			): WebResourceResponse? = documentation.intercept(request) ?: super.shouldInterceptRequest(view, request)
+			): WebResourceResponse? = documentation?.intercept(request) ?: super.shouldInterceptRequest(view, request)
 
 			override fun shouldOverrideUrlLoading(view: WebView, request: WebResourceRequest): Boolean {
 				// Allow loading of local assets files

common/src/main/java/com/itsaky/androidide/activities/editor/HelpActivity.kt

@@ -70,7 +70,13 @@ class HelpActivity : BaseIDEActivity() {
 
 	// ADFA-5176: answers documentation requests from the database in-process, so loading a page
 	// no longer opens a TCP connection per asset to the local web server.
-	private val documentation = DocumentationRequestInterceptor.shared
+	//
+	// by lazy, not an initializer: forcing it here runs during Activity construction, before
+	// onCreate, on the main thread -- which both stats external storage for the sentinel under a
+	// StrictMode policy that reports it, and dies before this screen exists if the shared
+	// interceptor cannot be built. Touched from shouldInterceptRequest instead, on a WebView
+	// thread, the way FAQActivity does it.
+	private val documentation by lazy { DocumentationRequestInterceptor.shared }
 
 	// Wall-clock start of the page currently loading, for the ADFA-5176 measurement.
 	// elapsedRealtime, not currentTimeMillis: an NTP correction or a user clock change between
@@ -124,7 +130,10 @@ class HelpActivity : BaseIDEActivity() {
 					override fun shouldInterceptRequest(
 						view: android.webkit.WebView,
 						request: android.webkit.WebResourceRequest,
-					): android.webkit.WebResourceResponse? = documentation.intercept(request) ?: super.shouldInterceptRequest(view, request)
+					): android.webkit.WebResourceResponse? {
+						val intercepted = documentation?.intercept(request)
+						return intercepted ?: super.shouldInterceptRequest(view, request)
+					}
 
 					override fun onPageStarted(
 						view: android.webkit.WebView?,
@@ -150,7 +159,7 @@ class HelpActivity : BaseIDEActivity() {
 								"Loaded '{}' in {} ms; in-process totals so far: {}.",
 								url,
 								SystemClock.elapsedRealtime() - pageLoadStartMillis,
-								documentation.servedSummary(),
+								documentation?.servedSummary(),
 							)
 							pageLoadStartMillis = 0L
 						}

common/src/main/java/com/itsaky/androidide/documentation/DocumentationRequestInterceptor.kt

@@ -123,13 +123,28 @@ class DocumentationRequestInterceptor(
 		 * a WebView can outlive that, and neither should be able to close the other's handle. The
 		 * cost of the second handle is SQLite's page cache plus the dictionary, a few MB.
 		 */
-		val shared: DocumentationRequestInterceptor by lazy {
-			DocumentationRequestInterceptor(
-				DocumentationContentSource(
-					Environment.DOC_DB,
-					File(getExternalStorageDirectory(), "Download/documentation.db"),
-				),
-			)
+		val shared: DocumentationRequestInterceptor? by lazy {
+			// Null when Environment.init() has not run, which is a real state, not a defensive
+			// nicety: DeviceProtectedApplicationLoader wraps that call in runCatching, and the
+			// credential-protected loader returns before it when storage is not ready. DOC_DB is a
+			// plain static File with no initializer, so it is null in both cases, and the non-null
+			// parameter below turns that into an NPE at the first touch of this property. Declining
+			// instead puts the request on the local web server, which is exactly what a null return
+			// from intercept() already means everywhere else.
+			val database = Environment.DOC_DB
+			if (database == null) {
+				LoggerFactory
+					.getLogger(DocumentationRequestInterceptor::class.java)
+					.warn("Environment.DOC_DB is not set; documentation requests stay on the web server.")
+				null
+			} else {
+				DocumentationRequestInterceptor(
+					DocumentationContentSource(
+						database,
+						File(getExternalStorageDirectory(), "Download/documentation.db"),
+					),
+				)
+			}
 		}
 	}
 }