Open transcript file links in explorer

app/androidApp/src/main/kotlin/com/example/aiapp/MarkdownLinks.kt

@@ -32,6 +32,7 @@ import com.mikepenz.markdown.model.markdownAnnotator
 import com.mikepenz.markdown.utils.getUnescapedTextInNode
 import com.mikepenz.markdown.utils.resolveImageAlt
 import com.mikepenz.markdown.utils.resolveImageLink
+import java.net.URI
 import org.intellij.markdown.MarkdownElementTypes
 import org.intellij.markdown.MarkdownTokenTypes
 import org.intellij.markdown.ast.ASTNode
@@ -89,6 +90,7 @@ fun LinkedText(content: String, node: ASTNode, style: TextStyle, modifier: Modif
             content.buildMarkdownAnnotatedString(node, style, settings)
         }
     val uriHandler = LocalUriHandler.current
+    val fileLinkHandler = LocalFileLinkHandler.current
     val onPlainTap = LocalMarkdownTap.current
     val layout = remember { Ref<TextLayoutResult>() }
     // The renderer's own rule for a style that names no colour: the theme's text colour.
@@ -127,7 +129,7 @@ fun LinkedText(content: String, node: ASTNode, style: TextStyle, modifier: Modif
                     when {
                         url != null -> {
                             up.consume()
-                            uriHandler.openUri(url)
+                            if (fileLinkHandler?.invoke(url) != true) uriHandler.openUri(url)
                         }
                         onPlainTap != null -> {
                             up.consume()
@@ -164,6 +166,55 @@ fun LinkedText(content: String, node: ASTNode, style: TextStyle, modifier: Modif
  */
 val LocalMarkdownTap = compositionLocalOf<(() -> Unit)?> { null }
 
+/**
+ * Opens a markdown destination inside the current session when it names a file on that session's
+ * machine. Null outside a session, where every link keeps its ordinary URI behaviour.
+ */
+val LocalFileLinkHandler = compositionLocalOf<((String) -> Boolean)?> { null }
+
+/**
+ * A stable markdown link handler whose behaviour follows the latest [onFile]. Keeping its identity
+ * stable matters: every visible markdown paragraph reads it, and a session recomposes on every
+ * streamed event.
+ */
+@Composable
+fun rememberFileLinkHandler(onFile: (String) -> Unit): (String) -> Boolean {
+    val latest = rememberUpdatedState(onFile)
+    return remember {
+        { destination ->
+            val path = filePathOf(destination)
+            if (path == null) false
+            else {
+                latest.value(path)
+                true
+            }
+        }
+    }
+}
+
+/**
+ * The path named by a local-file markdown destination.
+ *
+ * Only absolute paths and local `file:` URIs are claimed. A relative destination might be a web
+ * link, and sending one to a machine's filesystem would silently give an ordinary link a different
+ * meaning. Editors commonly append a line and optional column; the current viewer opens the file
+ * itself, so those coordinates are removed here.
+ */
+internal fun filePathOf(destination: String): String? {
+    val uri = runCatching { URI(destination) }.getOrNull()
+    val path =
+        when {
+            destination.startsWith("/") && !destination.startsWith("//") ->
+                uri?.path ?: destination.substringBefore('#').substringBefore('?')
+            uri != null &&
+                uri.scheme.equals("file", ignoreCase = true) &&
+                (uri.host.isNullOrEmpty() || uri.host == "localhost") -> uri.path
+            else -> null
+        }
+    if (path.isNullOrEmpty() || !path.startsWith('/')) return null
+    return path.replace(Regex(":\\d+(?::\\d+)?$"), "")
+}
+
 /**
  * [onTap] as a stable value to provide for [LocalMarkdownTap]. The identity stays put while the
  * behaviour follows the latest [onTap], which is what keeps providing it from invalidating the text