Fix camera to open system camera app; harden logbook storage; add backlog

Camera:
- Replace ActivityResultContracts.TakePicture() with explicit
  StartActivityForResult + Intent(ACTION_IMAGE_CAPTURE) + EXTRA_OUTPUT
  so the full system camera app always opens (not a sub-view preview)
- FLAG_GRANT_WRITE_URI_PERMISSION added for camera app FileProvider access

LogbookStorage:
- getExternalFilesDir() can return null when external storage is
  unavailable; fall back to filesDir for both storageFile and photoDir
  so saves never silently fail on devices without external storage

Backlog (worklog.md):
- Add notes/photos to finished tracks + include in trip report
- Trip report voice: replace generic style picker with single Nav voice
- Fix tack detection false positives at low SOG
- Investigate/fix speed coloring in MapLibre Android 11.x

https://claude.ai/code/session_01YUbuZNDAoLea4cf9UGQ9qn

3 files changed, 23 insertions, 8 deletions

diff --git a/.agent/worklog.md b/.agent/worklog.md
index 55fd5a7..cfae053 100644
--- a/.agent/worklog.md
+++ b/.agent/worklog.md
@@ -1,5 +1,15 @@
 # SESSION_STATE.md
 
+## Backlog (fix later)
+
+- **Add notes/photos to a finished track** — UI to attach logbook entries to a past track by timestamp/geo proximity. Must flow into the trip report (currently only live-session entries are scoped).
+
+- **Trip report voice** — The current narrative styles (Professional / Adventurous / Journal / Pirate) are generic and not right for Nav. Nav is an opinionated sailing app; the report should have a single voice that reflects that — concise, knowledgeable, seamanlike. Rip out the style picker and write one good template.
+
+- **Tack detection is buggy, especially at low speed** — False positives at low SOG (GPS heading noise looks like tacks). Need minimum-SOG gate (e.g. skip detection when SOG < 1.5 kt) and review the stability window / MIN_DELTA thresholds against real tracks.
+
+- **Speed coloring on the map doesn't work** — `Expression.get("color")` on a FeatureCollection of 2-point LineStrings fails silently in MapLibre Android 11.x. The focused-track layer in MapHandler still uses this broken approach. Needs investigation: either find a working data-driven expression syntax for this MapLibre version, or pre-segment the GeoJSON differently.
+
 ## Current Task Goal
 Instrument Sheet Visual Redesign — IN PROGRESS (2026-04-06)
 
diff --git a/android-app/app/src/main/kotlin/org/terst/nav/logbook/LogbookStorage.kt b/android-app/app/src/main/kotlin/org/terst/nav/logbook/LogbookStorage.kt
index 6b90542..51f1f09 100644
--- a/android-app/app/src/main/kotlin/org/terst/nav/logbook/LogbookStorage.kt
+++ b/android-app/app/src/main/kotlin/org/terst/nav/logbook/LogbookStorage.kt
@@ -16,10 +16,10 @@ class LogbookStorage(private val context: Context) {
     private val adapter = moshi.adapter(LogEntryList::class.java)
 
     private val storageFile: File
-        get() = File(context.getExternalFilesDir(null), "nav_logbook.json")
+        get() = File(context.getExternalFilesDir(null) ?: context.filesDir, "nav_logbook.json")
 
     val photoDir: File
-        get() = File(context.getExternalFilesDir(Environment.DIRECTORY_PICTURES), "Nav")
+        get() = File(context.getExternalFilesDir(Environment.DIRECTORY_PICTURES) ?: context.filesDir, "Nav")
             .also { it.mkdirs() }
 
     fun loadAll(): List<LogEntry> = runCatching {
diff --git a/android-app/app/src/main/kotlin/org/terst/nav/ui/voicelog/VoiceLogFragment.kt b/android-app/app/src/main/kotlin/org/terst/nav/ui/voicelog/VoiceLogFragment.kt
index 3638f8f..2557eb4 100644
--- a/android-app/app/src/main/kotlin/org/terst/nav/ui/voicelog/VoiceLogFragment.kt
+++ b/android-app/app/src/main/kotlin/org/terst/nav/ui/voicelog/VoiceLogFragment.kt
@@ -1,12 +1,14 @@
 package org.terst.nav.ui.voicelog
 
 import android.Manifest
+import android.app.Activity
 import android.content.Intent
 import android.content.pm.PackageManager
 import android.graphics.BitmapFactory
 import android.net.Uri
 import android.os.Build
 import android.os.Bundle
+import android.provider.MediaStore
 import android.speech.RecognitionListener
 import android.speech.RecognizerIntent
 import android.speech.SpeechRecognizer
@@ -73,9 +75,9 @@ class VoiceLogFragment : Fragment() {
     private var pendingCameraUri: Uri? = null
 
     private val cameraLauncher = registerForActivityResult(
-        ActivityResultContracts.TakePicture()
-    ) { success: Boolean ->
-        if (success) {
+        ActivityResultContracts.StartActivityForResult()
+    ) { result ->
+        if (result.resultCode == Activity.RESULT_OK) {
             val path = pendingPhotoPath ?: return@registerForActivityResult
             setPhoto(path) {
                 val bm = BitmapFactory.decodeFile(path)
@@ -140,13 +142,16 @@ class VoiceLogFragment : Fragment() {
         fabMic.setOnClickListener { startListening() }
 
         btnCamera.setOnClickListener {
-            val dir = NavApplication.logbookRepository.photoDir
-            val file = File(dir, "log_${System.currentTimeMillis()}.jpg")
+            val file = File(NavApplication.logbookRepository.photoDir, "log_${System.currentTimeMillis()}.jpg")
             pendingPhotoPath = file.absolutePath
             pendingCameraUri = FileProvider.getUriForFile(
                 requireContext(), "${requireContext().packageName}.fileprovider", file
             )
-            cameraLauncher.launch(pendingCameraUri!!)
+            val intent = Intent(MediaStore.ACTION_IMAGE_CAPTURE).apply {
+                putExtra(MediaStore.EXTRA_OUTPUT, pendingCameraUri)
+                addFlags(Intent.FLAG_GRANT_WRITE_URI_PERMISSION)
+            }
+            cameraLauncher.launch(intent)
         }
 
         btnGallery.setOnClickListener { galleryLauncher.launch("image/*") }