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Phase 1 of docs/frost-batch-signing.md, which is added here as the plan the next phases follow. Schema only: a session still signs exactly one event, the wire is byte-identical, and every existing test passes on the moved columns. ## What moved, and why it had to A batch of k events is k independent FROST instances sharing a signer set, not one signature over k messages. That is forced rather than chosen: a Schnorr partial signature is `s = k + e·x` with `e = H(R‖P‖m)`, so two messages under one nonce R give two equations in one unknown and the secret share falls out. So the five columns that enter that equation -- unsignedEventJson, eventId, nonceRandom, aggregatedNonce, signature -- move to a child table keyed (sessionId, itemIndex). What stays on FrostSigningSession is everything outside it: the ceremony, the threshold, the derivation path, the signer set, and the one approval. itemIndex is protocol rather than presentation -- nonces and partial signatures are joined positionally against it -- so getItems() orders by it and nothing re-sorts. Spelled itemIndex rather than index to keep hand-written queries free of backticks. No itemCount column. The count is a COUNT(*), for the same reason signerIds is derived from the ceremony's participant order rather than stored: a denormalised count is one more thing that can disagree with the rows. ## Migration 9 -> 10 Manual, not auto: Room can create the table and drop the columns but cannot copy between them, and the copy is the whole point. A session in flight at upgrade holds its nonce seed and the aggregate it is already signing against, and neither can be regenerated -- losing either makes the next pass derive a different nonce for the same message and publish a second partial signature over it, which is the extraction case. Both are copied verbatim into item 0, so an in-flight session resumes as though nothing happened. Removing the columns uses ALTER TABLE DROP COLUMN rather than the usual create-copy-drop-rename rebuild. FrostSignerMessage and FrostSigningItem both reference FrostSigningSession(id) ON DELETE CASCADE, and DROP TABLE fires cascades -- with foreign keys enforced the rebuild would delete every signer message and every item just written. Whether it does depends on Room disabling foreign keys around migrations, which is not worth depending on when DROP COLUMN cannot go wrong. It needs SQLite 3.35 and unindexed, unconstrained columns; these five qualify, and getRoomDatabase pins BundledSQLiteDriver on every platform. ## Invariants established here for the phases that follow - signerIds and every item's aggregatedNonce are one write-once unit, applied by applyAggregate() -- items first in one transaction, then the session, so "some items aggregated" is unreachable and signerIds != null stays the gate. - Signatures likewise, via applySignatures(); isSigned() counts rows instead of reading a flag. - complete() verifies every signature before applying any event, so a batch is all-or-nothing rather than half-filed. - itemsOver() gives each item its own 32 bytes of seed. Independent seeds mean an off-by-one in index handling produces a session that fails to aggregate rather than one that signs two messages under a single nonce. signedEvent() and isAwaitingApproval() now take the item(s) rather than the session, which propagates to the repository, the view model and the screen. advance() reads items.first() and Phase 2 turns that into a loop. ## Tests - FrostSigningSessionDaoJvmTest: index ordering, single-item read, upsert replacing rather than accumulating, signed-item counting, cascade delete. - FrostSigningItemMigrationJvmTest (new): the backfill against a real v9 database, asserting the seed and aggregate values survive -- not merely that a row appeared -- plus the exact column lists Room will check at open time. - 338 jvmTest and 217 testDebugUnitTest pass. Co-Authored-By: Claude Opus 5 <noreply@anthropic.com>
This is a Kotlin Multiplatform project targeting Android, iOS, Desktop (JVM).
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/composeApp is for code that will be shared across your Compose Multiplatform applications. It contains several subfolders:
- commonMain is for code that’s common for all targets.
- Other folders are for Kotlin code that will be compiled for only the platform indicated in the folder name. For example, if you want to use Apple’s CoreCrypto for the iOS part of your Kotlin app, the iosMain folder would be the right place for such calls. Similarly, if you want to edit the Desktop (JVM) specific part, the jvmMain folder is the appropriate location.
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/iosApp contains iOS applications. Even if you’re sharing your UI with Compose Multiplatform, you need this entry point for your iOS app. This is also where you should add SwiftUI code for your project.
Build and Run Android Application
To build and run the development version of the Android app, use the run configuration from the run widget in your IDE’s toolbar or build it directly from the terminal:
- on macOS/Linux
./gradlew :composeApp:assembleDebug - on Windows
.\gradlew.bat :composeApp:assembleDebug
Build and Run Desktop (JVM) Application
To build and run the development version of the desktop app, use the run configuration from the run widget in your IDE’s toolbar or run it directly from the terminal:
- on macOS/Linux
./gradlew :composeApp:run - on Windows
.\gradlew.bat :composeApp:run
Build and Run iOS Application
To build and run the development version of the iOS app, use the run configuration from the run widget in your IDE’s toolbar or open the /iosApp directory in Xcode and run it from there.
Learn more about Kotlin Multiplatform…