feat: Phase 4-5 VCard import, dedup/merge, Stream G tests

android/app/build.gradle.kts

@@ -116,4 +116,6 @@ dependencies {
     testImplementation("junit:junit:4.13.2")
     testImplementation("org.mockito:mockito-core:5.14.2")
     testImplementation("org.mockito.kotlin:mockito-kotlin:5.4.0")
+    testImplementation("org.jetbrains.kotlinx:kotlinx-coroutines-test:1.8.1")
+    testImplementation("androidx.arch.core:core-testing:2.2.0")
 }

android/app/src/androidTest/java/com/cardsnap/tests/ContactsTest.kt

@@ -38,4 +38,15 @@ class ContactsTest {
         composeRule.onNodeWithText("Back").performClick()
         composeRule.onNodeWithTag("scan-screen").assertIsDisplayed()
     }
+
+    @Test fun contacts_05_importButton_isVisible() {
+        composeRule.onNodeWithTag("contacts-button").performClick()
+        composeRule.onNodeWithTag("import-vcard-button").assertIsDisplayed()
+    }
+
+    @Test fun contacts_06_exportButton_visibleAfterImport() {
+        composeRule.onNodeWithTag("contacts-button").performClick()
+        composeRule.onNodeWithTag("import-vcard-button").assertIsDisplayed()
+        composeRule.onNodeWithTag("export-all-contacts-button").assertIsDisplayed()
+    }
 }

android/app/src/main/java/com/cardsnap/domain/ContactConfidenceScorer.kt

@@ -0,0 +1,65 @@
+package com.cardsnap.domain
+
+import com.cardsnap.domain.model.ContactCard
+
+sealed interface Confidence {
+    object HIGH : Confidence
+    object MEDIUM : Confidence
+    object LOW : Confidence
+}
+
+object ContactConfidenceScorer {
+
+    fun score(contact: ContactCard, ocrRawText: String): Confidence {
+        val hasRealName = contact.name.isNotBlank() && looksLikeRealName(contact.name)
+        val hasEmail = contact.email.isNotBlank()
+        val hasPhone = contact.phone.isNotBlank()
+        val hasCompany = contact.company.isNotBlank()
+        val hasTitle = contact.title.isNotBlank()
+        val hasMeaningfulField = hasRealName || hasEmail || hasPhone || hasCompany || hasTitle
+
+        if (isGarbageOcr(ocrRawText) && !hasMeaningfulField) return Confidence.LOW
+
+        if (hasRealName && (hasEmail || hasPhone || hasCompany)) return Confidence.HIGH
+
+        if (hasMeaningfulField) return Confidence.MEDIUM
+
+        return Confidence.LOW
+    }
+
+    fun isValid(contact: ContactCard, ocrRawText: String): Boolean =
+        score(contact, ocrRawText) == Confidence.HIGH
+
+    internal fun looksLikeRealName(name: String): Boolean {
+        val trimmed = name.trim()
+        if (trimmed.length < 2 || trimmed.length > 80) return false
+
+        val letterCount = trimmed.count { it.isLetter() }
+        if (letterCount < 2) return false
+
+        val alphaRatio = letterCount.toFloat() / trimmed.length
+        if (alphaRatio < 0.4f) return false
+
+        val words = trimmed.split(Regex("\\s+")).filter { it.isNotBlank() }
+        if (words.isEmpty()) return false
+
+        return true
+    }
+
+    internal fun isGarbageOcr(text: String): Boolean {
+        val trimmed = text.trim()
+        if (trimmed.isBlank()) return true
+
+        val words = trimmed.split(Regex("\\s+")).filter { it.isNotBlank() }
+        if (words.size < 2 && words.all { it.length < 3 }) return true
+
+        val symbolCount = trimmed.count { !it.isLetterOrDigit() && !it.isWhitespace() }
+        val symbolRatio = symbolCount.toFloat() / trimmed.length
+        if (symbolRatio > 0.5f) return true
+
+        val letterCount = trimmed.count { it.isLetter() }
+        if (letterCount < 3) return true
+
+        return false
+    }
+}

android/app/src/main/java/com/cardsnap/domain/ContactDeduplicator.kt

@@ -0,0 +1,109 @@
+package com.cardsnap.domain
+
+import com.cardsnap.domain.model.ContactCard
+
+object ContactDeduplicator {
+
+    /**
+     * Normalized Levenshtein similarity: 1.0 = identical, 0.0 = completely different.
+     */
+    fun normalizedSimilarity(a: String, b: String): Double {
+        val aStr = a.trim().lowercase()
+        val bStr = b.trim().lowercase()
+        if (aStr == bStr) return 1.0
+        if (aStr.isEmpty() && bStr.isEmpty()) return 1.0
+        if (aStr.isEmpty() || bStr.isEmpty()) return 0.0
+        val maxLen = maxOf(aStr.length, bStr.length)
+        if (maxLen == 0) return 1.0
+        return 1.0 - levenshteinDistance(aStr, bStr).toDouble() / maxLen
+    }
+
+    /**
+     * Find exact duplicate pairs where email (non-blank) matches OR phone (non-blank) matches.
+     * Returns only the first matching pair per duplicate group.
+     * Only contacts with at least name OR email OR phone non-blank are considered.
+     */
+    fun findExactDuplicates(contacts: List<ContactCard>): List<Pair<ContactCard, ContactCard>> {
+        val valid = contacts.filter { it.name.isNotBlank() || it.email.isNotBlank() || it.phone.isNotBlank() }
+        val result = mutableListOf<Pair<ContactCard, ContactCard>>()
+        val matchedIds = mutableSetOf<String>()
+
+        valid.groupBy { it.email.trim().lowercase() }
+            .filter { it.key.isNotBlank() && it.value.size >= 2 }
+            .forEach { (_, group) ->
+                val unmatched = group.filter { it.id !in matchedIds }
+                if (unmatched.size >= 2) {
+                    result.add(Pair(unmatched[0], unmatched[1]))
+                    matchedIds.add(unmatched[0].id)
+                    matchedIds.add(unmatched[1].id)
+                }
+            }
+
+        valid.groupBy { it.phone.filter { c -> c.isDigit() } }
+            .filter { it.key.isNotBlank() && it.value.size >= 2 }
+            .forEach { (_, group) ->
+                val unmatched = group.filter { it.id !in matchedIds }
+                if (unmatched.size >= 2) {
+                    result.add(Pair(unmatched[0], unmatched[1]))
+                    matchedIds.add(unmatched[0].id)
+                    matchedIds.add(unmatched[1].id)
+                }
+            }
+
+        return result
+    }
+
+    /**
+     * Find fuzzy duplicate pairs where names have high similarity (> 0.8)
+     * OR same company + similar name (> 0.5).
+     * Filters out pairs already found by exact matching.
+     * Only contacts with at least name OR email OR phone non-blank are considered.
+     */
+    fun findFuzzyDuplicates(contacts: List<ContactCard>): List<Pair<ContactCard, ContactCard>> {
+        val valid = contacts.filter { it.name.isNotBlank() || it.email.isNotBlank() || it.phone.isNotBlank() }
+
+        val exactMatchedIds = findExactDuplicates(contacts)
+            .flatMap { listOf(it.first.id, it.second.id) }
+            .toSet()
+        val result = mutableListOf<Pair<ContactCard, ContactCard>>()
+        val matchedIds = exactMatchedIds.toMutableSet()
+
+        for (i in valid.indices) {
+            for (j in i + 1 until valid.size) {
+                val a = valid[i]
+                val b = valid[j]
+                if (a.id in matchedIds || b.id in matchedIds) continue
+
+                val nameSim = normalizedSimilarity(a.name, b.name)
+                val sameCompany = a.company.isNotBlank() &&
+                    a.company.equals(b.company, ignoreCase = true)
+                val sameCompanyAndSimilarName = sameCompany && nameSim > 0.5
+
+                if (nameSim > 0.8 || sameCompanyAndSimilarName) {
+                    result.add(Pair(a, b))
+                    matchedIds.add(a.id)
+                    matchedIds.add(b.id)
+                }
+            }
+        }
+
+        return result
+    }
+
+    private fun levenshteinDistance(a: String, b: String): Int {
+        val dp = Array(a.length + 1) { IntArray(b.length + 1) }
+        for (i in 0..a.length) dp[i][0] = i
+        for (j in 0..b.length) dp[0][j] = j
+        for (i in 1..a.length) {
+            for (j in 1..b.length) {
+                val cost = if (a[i - 1] == b[j - 1]) 0 else 1
+                dp[i][j] = minOf(
+                    dp[i - 1][j] + 1,
+                    dp[i][j - 1] + 1,
+                    dp[i - 1][j - 1] + cost
+                )
+            }
+        }
+        return dp[a.length][b.length]
+    }
+}

android/app/src/main/java/com/cardsnap/domain/model/ContactsState.kt

@@ -0,0 +1,11 @@
+package com.cardsnap.domain.model
+
+sealed interface ContactsState {
+    data object Loading : ContactsState
+
+    data class Success(val contacts: List<ContactCard>) : ContactsState
+
+    data class Error(val message: String) : ContactsState
+
+    data object Empty : ContactsState
+}

android/app/src/main/java/com/cardsnap/domain/model/ScanError.kt

@@ -0,0 +1,41 @@
+package com.cardsnap.domain.model
+
+sealed class ScanError(
+    open val message: String,
+    open val userFacingMessage: String
+) {
+    data object CameraPermissionDenied : ScanError(
+        message = "Camera permission was denied by the user",
+        userFacingMessage = "Camera permission is required to scan business cards. Please grant it in Settings."
+    )
+
+    data class OcrFailed(val cause: String) : ScanError(
+        message = "OCR processing failed: $cause",
+        userFacingMessage = "Could not read text from the image. Please try again with better lighting."
+    )
+
+    data class ParserFailed(val cause: String) : ScanError(
+        message = "Contact parsing failed: $cause",
+        userFacingMessage = "Could not extract contact details from the scanned text."
+    )
+
+    data object NoCardDetected : ScanError(
+        message = "No business card was detected in the image",
+        userFacingMessage = "No business card detected. Make sure the card is centered in the frame."
+    )
+
+    data class ImageProcessingFailed(val cause: String) : ScanError(
+        message = "Image processing failed: $cause",
+        userFacingMessage = "Failed to process the image. Please try again."
+    )
+
+    data object SaveFailed : ScanError(
+        message = "Failed to save the scanned contact",
+        userFacingMessage = "Could not save the contact. Please check your storage and try again."
+    )
+
+    data object Unknown : ScanError(
+        message = "An unknown error occurred",
+        userFacingMessage = "Something went wrong. Please try again."
+    )
+}

android/app/src/main/java/com/cardsnap/domain/model/ScanState.kt

@@ -0,0 +1,19 @@
+package com.cardsnap.domain.model
+
+sealed interface ScanState {
+    data object Idle : ScanState
+
+    data object Processing : ScanState
+
+    data class Results(
+        val contact: ContactCard,
+        val extractedText: String,
+        val imageUri: String
+    ) : ScanState
+
+    data class Saved(val contact: ContactCard) : ScanState
+
+    data class Error(val error: ScanError) : ScanState
+
+    data object Offline : ScanState
+}