feat(import): parse otpauth URIs and unencrypted Aegis JSON in resumable steps

Streaming JSON tokenizer with depth and length limits and native skipping
of long strings; Aegis reader for database versions 1-3 with groups and
encrypted-export detection; otpauth parser with ';' separators and Steam;
import job with Replace mode, duplicate and replacement checks, a sealed
multi-part buffer and a report. Google Authenticator exports deferred.

Co-Authored-By: Claude Opus 5.5 <noreply@anthropic.com>

1 files changed, 90 insertions, 0 deletions

diff --git a/source/import/ImportBuffer.mc b/source/import/ImportBuffer.mc
new file mode 100644
index 0000000..0aca548
--- /dev/null
+++ b/source/import/ImportBuffer.mc
@@ -0,0 +1,90 @@
+// Author:  cirakg & claude ai
+// Summary: Keeps the text of an unfinished multi-part import between syncs, sealed with the device key, capped and expiring.
+//
+// README 11.2: when pasted JSON is still incomplete, the watch keeps what it
+// got and waits for the next part. The text is sealed (SealedBox, device
+// key, aad "OTPW-IMP-1"), because it holds secrets, and split into chunks
+// below Application.Storage's 8 KB per value:
+//     "imp"     {"n" => chunk count, "t" => unix time saved}
+//     "imp.<i>" chunk i of the sealed box
+// Chunks are written before "imp", and "imp" is deleted first, so a torn
+// write leaves no readable half-buffer. Buffers older than MAX_AGE_S are
+// discarded.
+
+import Toybox.Application;
+import Toybox.Lang;
+
+module ImportBuffer {
+
+    const META_KEY = "imp";
+    const CHUNK_BYTES = 7000;
+    const MAX_TEXT_BYTES = 32768;
+    const MAX_AGE_S = 86400;
+    const AAD = "OTPW-IMP-1";
+
+    // The waiting text, or "" when there is none (or it expired or is damaged,
+    // in which case it is deleted).
+    function load(store as Persist.Backend, keys as SealedBox.Keys, now as Long) as String {
+        var meta = store.getValue(META_KEY);
+        if (!(meta instanceof Dictionary)) {
+            return "";
+        }
+        var n = meta["n"];
+        var t = meta["t"];
+        if (!(n instanceof Number) || !(t instanceof Long) || n < 1 || n > 16 || now - t > MAX_AGE_S || now < t) {
+            clear(store);
+            return "";
+        }
+        var box = []b;
+        for (var i = 0; i < n; i++) {
+            var chunk = store.getValue(META_KEY + "." + i);
+            if (!(chunk instanceof ByteArray)) {
+                clear(store);
+                return "";
+            }
+            box.addAll(chunk);
+        }
+        var plain = SealedBox.open(keys, Bytes.fromUtf8(AAD), box);
+        var text = plain != null ? Bytes.toUtf8(plain) : null;
+        Bytes.wipe(plain);
+        if (text == null) {
+            clear(store);
+            return "";
+        }
+        return text;
+    }
+
+    // Save text as the waiting import. Returns false (and saves nothing)
+    // when it is over MAX_TEXT_BYTES.
+    function save(store as Persist.Backend, keys as SealedBox.Keys, text as String, now as Long) as Boolean {
+        var plain = Bytes.fromUtf8(text);
+        if (plain.size() > MAX_TEXT_BYTES) {
+            Bytes.wipe(plain);
+            return false;
+        }
+        clear(store);
+        var box = SealedBox.seal(keys, Bytes.fromUtf8(AAD), plain);
+        Bytes.wipe(plain);
+        var n = 0;
+        for (var at = 0; at < box.size(); at += CHUNK_BYTES) {
+            store.setValue(META_KEY + "." + n, box.slice(at, at + CHUNK_BYTES < box.size() ? at + CHUNK_BYTES : box.size()));
+            n++;
+        }
+        store.setValue(META_KEY, {"n" => n, "t" => now} as Dictionary<Application.Storage.KeyType, Application.Storage.ValueType>);
+        return true;
+    }
+
+    function hasPending(store as Persist.Backend) as Boolean {
+        return store.getValue(META_KEY) != null;
+    }
+
+    // Delete the waiting import (after it completed, failed or was cancelled).
+    function clear(store as Persist.Backend) as Void {
+        var meta = store.getValue(META_KEY);
+        store.deleteValue(META_KEY);
+        var n = meta instanceof Dictionary && meta["n"] instanceof Number ? meta["n"] as Number : 16;
+        for (var i = 0; i < n && i < 16; i++) {
+            store.deleteValue(META_KEY + "." + i);
+        }
+    }
+}