Add system prompt customizatio for AI summaries

app/src/main/java/com/aryan/reader/AiSettingsScreen.kt

@@ -5,6 +5,7 @@ import androidx.compose.foundation.layout.Column
 import androidx.compose.foundation.layout.Row
 import androidx.compose.foundation.layout.fillMaxSize
 import androidx.compose.foundation.layout.fillMaxWidth
+import androidx.compose.foundation.layout.height
 import androidx.compose.foundation.layout.padding
 import androidx.compose.foundation.layout.statusBarsPadding
 import androidx.compose.foundation.rememberScrollState
@@ -13,6 +14,7 @@ import androidx.compose.material.icons.Icons
 import androidx.compose.material.icons.automirrored.filled.ArrowBack
 import androidx.compose.material.icons.filled.Check
 import androidx.compose.material.icons.filled.Delete
+import androidx.compose.material.icons.filled.Refresh
 import androidx.compose.material3.AlertDialog
 import androidx.compose.material3.Button
 import androidx.compose.material3.DropdownMenuItem
@@ -58,6 +60,12 @@ fun AiSettingsScreen(
         "gemini" to stringResource(R.string.provider_gemini),
         "groq" to stringResource(R.string.provider_groq),
     )
+    var promptText by remember {
+        mutableStateOf(
+            loadSummarizePrompt(context).ifBlank { DEFAULT_SUMMARIZE_PROMPT.trimIndent() }
+        )
+    }
+    var showResetPromptConfirm by remember { mutableStateOf(false) }
 
     fun refresh() {
         settings = loadAiByokSettings(context)
@@ -199,6 +207,52 @@ fun AiSettingsScreen(
                 options = listOf(AiModelOption("gemini", GEMINI_CLOUD_TTS_MODEL)),
                 onSelected = { updateModels(settings.copy(ttsModel = it)) }
             )
+
+            HorizontalDivider()
+
+            Row(
+                modifier = Modifier.fillMaxWidth(),
+                verticalAlignment = Alignment.CenterVertically,
+                horizontalArrangement = Arrangement.SpaceBetween
+            ) {
+                Column(modifier = Modifier.weight(1f)) {
+                    Text(
+                        "AI Page Explanation Prompt",
+                        style = MaterialTheme.typography.titleMedium,
+                        fontWeight = FontWeight.SemiBold
+                    )
+                    Text(
+                        "Customise the system instruction sent to the AI when explaining a book page. Leave as-is to use the built-in default.",
+                        style = MaterialTheme.typography.bodySmall,
+                        color = MaterialTheme.colorScheme.onSurfaceVariant
+                    )
+                }
+                IconButton(onClick = { showResetPromptConfirm = true }) {
+                    Icon(
+                        Icons.Default.Refresh,
+                        contentDescription = "Reset prompt to default"
+                    )
+                }
+            }
+
+            OutlinedTextField(
+                value = promptText,
+                onValueChange = { promptText = it },
+                modifier = Modifier
+                    .fillMaxWidth()
+                    .height(220.dp),
+                label = { Text("System Prompt") },
+                maxLines = Int.MAX_VALUE
+            )
+
+            Button(
+                onClick = {
+                    saveSummarizePrompt(context, promptText)
+                },
+                modifier = Modifier.align(Alignment.End)
+            ) {
+                Text("Save Prompt")
+            }
         }
     }
 
@@ -240,6 +294,24 @@ fun AiSettingsScreen(
             }
         )
     }
+
+    if (showResetPromptConfirm) {
+        AlertDialog(
+            onDismissRequest = { showResetPromptConfirm = false },
+            title = { Text("Reset Prompt") },
+            text = { Text("Restore the AI page explanation prompt to its built-in default? Your current edits will be lost.") },
+            confirmButton = {
+                TextButton(onClick = {
+                    resetSummarizePrompt(context)
+                    promptText = DEFAULT_SUMMARIZE_PROMPT.trimIndent()
+                    showResetPromptConfirm = false
+                }) { Text("Reset") }
+            },
+            dismissButton = {
+                TextButton(onClick = { showResetPromptConfirm = false }) { Text(stringResource(R.string.action_cancel)) }
+            }
+        )
+    }
 }
 
 @Composable

app/src/main/java/com/aryan/reader/Common.kt

@@ -241,6 +241,7 @@ private const val PREF_AI_MODEL_SUMMARIZE = "model_summarize"
 private const val PREF_AI_MODEL_RECAP = "model_recap"
 private const val PREF_AI_TTS_MODEL = "tts_model"
 private const val PREF_AI_MODEL_EMPTY_MIGRATION_DONE = "model_empty_migration_done"
+private const val PREF_AI_SUMMARIZE_PROMPT = "summarize_prompt"
 private const val AI_KEYSTORE_ALIAS = "reader_ai_byok_key_v1"
 private const val ENCRYPTION_PREFIX = "v1:"
 const val GEMINI_CLOUD_TTS_MODEL = "gemini-3.1-flash-live-preview"
@@ -272,6 +273,17 @@ data class AiModelOption(
     val id: String = "$provider:$name"
 }
 
+const val DEFAULT_SUMMARIZE_PROMPT = """
+    System Role: You are an expert technical educator. You will be given an image of a page. Your task is to rewrite the provided page from a technical book into a clear, spoken-word explanation. You are not summarizing (don't skip details), and you are not translating literally (don't be robotic). You are explaining.
+    Task Instructions:
+        Preserve Technical Accuracy: Keep all specific terms, variables, and core logic. Do not omit the "meat" of the technical content.
+        Conversational Bridge: Use transition phrases like "Looking at the next section," "Essentially, this means," or "To put that into practice." This helps the listener follow along without seeing the page.
+        Handle Visuals/Code: If the text refers to a diagram or a code block, describe it briefly (e.g., "The code shows a loop where...") rather than reading out syntax like 'bracket, semicolon.'
+        Audio-First Formatting:
+            Write in full, flowing sentences.
+            Strictly No Markdown: No asterisks, bolding, or bullet points.
+            Use words for symbols if they are vital (e.g., say "plus" instead of "+")."""
+
 data class AiByokSettings(
     val geminiKey: String = "",
     val groqKey: String = "",
@@ -280,7 +292,8 @@ data class AiByokSettings(
     val defineModel: String = "",
     val summarizeModel: String = "",
     val recapModel: String = "",
-    val ttsModel: String = ""
+    val ttsModel: String = "",
+    val summarizePrompt: String = ""
 )
 
 val aiByokModelOptions = listOf(
@@ -366,7 +379,8 @@ fun loadAiByokSettings(context: Context): AiByokSettings {
         defineModel = prefs.getString(PREF_AI_MODEL_DEFINE, "") ?: "",
         summarizeModel = prefs.getString(PREF_AI_MODEL_SUMMARIZE, "") ?: "",
         recapModel = prefs.getString(PREF_AI_MODEL_RECAP, "") ?: "",
-        ttsModel = prefs.getString(PREF_AI_TTS_MODEL, "") ?: ""
+        ttsModel = prefs.getString(PREF_AI_TTS_MODEL, "") ?: "",
+        summarizePrompt = prefs.getString(PREF_AI_SUMMARIZE_PROMPT, "") ?: ""
     )
     val geminiStored = prefs.getString(PREF_AI_GEMINI_KEY, "").orEmpty()
     val groqStored = prefs.getString(PREF_AI_GROQ_KEY, "").orEmpty()
@@ -388,9 +402,22 @@ fun saveAiByokSettings(context: Context, settings: AiByokSettings) {
         putString(PREF_AI_MODEL_SUMMARIZE, settings.summarizeModel)
         putString(PREF_AI_MODEL_RECAP, settings.recapModel)
         putString(PREF_AI_TTS_MODEL, settings.ttsModel)
+        putString(PREF_AI_SUMMARIZE_PROMPT, settings.summarizePrompt)
     }
 }
 
+fun loadSummarizePrompt(context: Context): String {
+    return context.aiPrefs().getString(PREF_AI_SUMMARIZE_PROMPT, "").orEmpty()
+}
+
+fun saveSummarizePrompt(context: Context, prompt: String) {
+    context.aiPrefs().edit { putString(PREF_AI_SUMMARIZE_PROMPT, prompt) }
+}
+
+fun resetSummarizePrompt(context: Context) {
+    context.aiPrefs().edit { putString(PREF_AI_SUMMARIZE_PROMPT, "") }
+}
+
 fun saveAiByokKey(context: Context, provider: String, key: String) {
     val current = loadAiByokSettings(context)
     val updated = when (provider) {

app/src/main/java/com/aryan/reader/pdf/PdfViewerScreen.kt

@@ -233,6 +233,8 @@ import com.aryan.reader.TtsSettingsSheet
 import com.aryan.reader.TtsWordReplacementsSheet
 import com.aryan.reader.areReaderAiFeaturesEnabled
 import com.aryan.reader.callByokGeminiInlineAi
+import com.aryan.reader.DEFAULT_SUMMARIZE_PROMPT
+import com.aryan.reader.loadSummarizePrompt
 import com.aryan.reader.cardTitle
 import com.aryan.reader.epubreader.AutoScrollControls
 import com.aryan.reader.epubreader.DictionarySettingsDialog
@@ -482,6 +484,7 @@ fun PdfViewerScreen(
         }
     }
     var documentMetadataTitle by remember { mutableStateOf<String?>(null) }
+    var documentMetadataAuthor by remember { mutableStateOf<String?>(null) }
     val activeLibraryItem by remember(uiState.allRecentFiles, uiState.rawLibraryFiles, uiState.recentFiles, uiState.selectedBookId, effectivePdfUri) {
         derivedStateOf {
             uiState.selectedBookId?.let { selectedId ->
@@ -3073,12 +3076,29 @@ fun PdfViewerScreen(
                 @Suppress("KotlinConstantConditions")
                 if (BuildConfig.FLAVOR == "oss") {
                     val fullText = StringBuilder()
+                    val bookName = documentMetadataTitle ?: originalFileName
+                    val authorName = documentMetadataAuthor ?: uiState.recentFiles.find { it.uriString == effectivePdfUri.toString() }?.author ?: "Unknown Author"
+                    val displayPageNumber = currentPage + 1
+
+                    val userPromptBase = loadSummarizePrompt(context)
+                        .ifBlank { DEFAULT_SUMMARIZE_PROMPT.trimIndent() }
+                    val systemInstruction = """
+                        $userPromptBase
+                        Output Structure:
+                        "On page $displayPageNumber, the author explains [Insert the adapted technical explanation here]."
+                        [Data Delimiter]
+                        Below is the book details from which image is took. Please process this text according to the instructions above:
+                        Book name: $bookName
+                        Author: $authorName
+                        page number: $displayPageNumber
+                    """.trimIndent()
+
                     callByokGeminiInlineAi(
                         context = context,
                         feature = AiFeature.SUMMARIZE,
                         mimeType = "image/jpeg",
                         base64Data = base64Image,
-                        systemInstruction = "You are an expert in analyzing visual content. You will be given an image of a page. Describe what is happening, identify key information, and summarize the text. Do not add a preamble.",
+                        systemInstruction = systemInstruction,
                         temperature = 0.2,
                         maxTokens = 8192,
                         onUpdate = {
@@ -3592,6 +3612,7 @@ fun PdfViewerScreen(
         isDocumentReady = false
         errorMessage = null
         documentMetadataTitle = null
+        documentMetadataAuthor = null
         isPrintBlockedForPasswordProtectedPdf = false
         currentBookId = null
         areAnnotationsLoaded = false
@@ -3730,6 +3751,11 @@ fun PdfViewerScreen(
                         wrapper.pdfDocument.getDocumentMeta().title?.takeIf { it.isNotBlank() }
                     }
                 }
+                documentMetadataAuthor = (doc as? PdfDocumentWrapper)?.let { wrapper ->
+                    PdfiumEngineProvider.withPdfium {
+                        wrapper.pdfDocument.getDocumentMeta().author?.takeIf { it.isNotBlank() }
+                    }
+                }
                 Timber.tag(PDF_RENAME_TRACE_TAG).i(
                     "pdfScreen.openEffect.metadataLoaded bookId=$currentBookId uri=$effectivePdfUri " +
                         "documentMetadataTitle=$documentMetadataTitle activeCustomName=${activeLibraryItem?.customName} " +