dashpay · shumkov · Aug 26, 2026 · Aug 9, 2026 · Aug 10, 2026 · Aug 11, 2026
@@ -99,6 +99,27 @@ sealed class DashSdkError(
         class AssetLockFundingMismatch(message: String, cause: Throwable? = null) :
             PlatformWallet(message, cause)
 
+        /**
+         * `ErrorAssetLockInsufficientFunds` (native code 29). Asset-lock coin
+         * selection came up short on the ONE funds account the caller selected
+         * — asset-lock funding never unions across accounts, so another source
+         * must be named explicitly rather than combined automatically.
+         *
+         * Distinct from [CoreInsufficientFunds] (22), which is the atomic
+         * Core-send selector rather than the asset-lock builder. The shortfall
+         * figures travel in [message] as `available {n} duffs, required {n}
+         * duffs` — the native result is ABI-frozen to code + message, so there
+         * are no structured fields to read.
+         *
+         * Raised by
+         * [shieldedFundFromCoinJoinDrain][org.dashfoundation.dashsdk.wallet.PlatformWalletManager.shieldedFundFromCoinJoinDrain]
+         * when the CoinJoin account has nothing to drain, and by
+         * [shieldedFundFromAssetLock][org.dashfoundation.dashsdk.wallet.PlatformWalletManager.shieldedFundFromAssetLock]
+         * when the funding account cannot cover the requested lock.
+         */
+        class AssetLockInsufficientFunds(message: String, cause: Throwable? = null) :
+            PlatformWallet(message, cause)
+
         /**
          * `ErrorShieldedNoRecordedAnchor` (native code 19). A shielded spend
          * could not be built against a Platform-recorded anchor because the
@@ -470,10 +491,11 @@ sealed class DashSdkError(
             24 -> PlatformWallet.AssetLockAlreadyConsumed(message, cause) // ErrorAssetLockAlreadyConsumed
             25 -> PlatformWallet.AssetLockFundingMismatch(message, cause) // ErrorAssetLockFundingMismatch
             26 -> PlatformWallet.TransactionBroadcastRejected(message, cause) // ErrorTransactionBroadcastRejected
+            29 -> PlatformWallet.AssetLockInsufficientFunds(message, cause) // ErrorAssetLockInsufficientFunds
             // The deferred-token trio sits at the contiguous block 34-36 because
             // 27-33 are claimed elsewhere: 27 ErrorShutdownIncomplete
             // (dashpay/platform#4268, merged), 29 ErrorAssetLockInsufficientFunds
-            // (#4184), 31 ErrorSigningKeyUnavailable (#4183/#4259), 32
+            // (mapped above), 31 ErrorSigningKeyUnavailable (#4183/#4259), 32
             // ErrorTransactionBuild (#4247/#4256), 33 ErrorTransactionSigning
             // (#4256). See packages/rs-platform-wallet-ffi/ERROR_CODE_REGISTRY.md.
             34 -> PlatformWallet.StaleReservationToken(message, cause) // ErrorStaleReservationToken

@@ -62,6 +62,26 @@ internal object FundingNative {
         coreSignerHandle: Long,
     )
 
+    /**
+     * Fund the shielded pool by DRAINING the wallet's CoinJoin account into a
+     * single asset lock (bridges
+     * `platform_wallet_manager_shielded_fund_from_asset_lock_coinjoin_drain`).
+     * Sibling of [shieldedFundFromAssetLock] with drain funding: there is no
+     * amount (the lock value is `Σ inputs − L1 fee`, computed Rust-side) and no
+     * surplus output (the single-recipient remainder flow pins it to zero).
+     * [coinJoinAccountIndex] selects the CoinJoin account to drain;
+     * [recipientRaw43] is the 43-byte raw Orchard address; [coreSignerHandle]
+     * is the manager's `MnemonicResolverHandle`. Blocks for the ~30s Halo 2
+     * proof; the note arrives on the next shielded sync.
+     */
+    external fun shieldedFundFromCoinJoinDrain(
+        managerHandle: Long,
+        walletId: ByteArray,
+        coinJoinAccountIndex: Int,
+        recipientRaw43: ByteArray,
+        coreSignerHandle: Long,
+    )
+
     /**
      * Resume a stuck shielded fund-from-asset-lock by outpoint (bridges
      * `platform_wallet_manager_shielded_resume_fund_from_asset_lock`).

@@ -1480,6 +1480,54 @@ class PlatformWalletManager(
         }
     }
 
+    /**
+     * Fund a wallet's shielded (Orchard) pool by DRAINING its CoinJoin account
+     * (`m/9'/coinType'/4'/coinJoinAccountIndex'`) into a single asset lock —
+     * port of Swift's `shieldedFundFromCoinJoinDrain`.
+     *
+     * Sibling of [shieldedFundFromAssetLock] with drain funding, which is what
+     * makes this the CoinJoin → Shielded migration path: every final mixed-coin
+     * UTXO is consumed and the lock value is `Σ inputs − L1 fee`, computed
+     * Rust-side, so the mixed coins never hop through a transparent BIP44
+     * address on the way in. Hence no amount parameter, and no surplus output
+     * (the single-recipient remainder flow pins the consensus surplus to zero).
+     *
+     * The recipient receives `lockValue − poolFee` credits. The Rust preflight
+     * rejects a drain whose balance could not clear the Type 18 pool fee, so an
+     * unrecoverable dust lock is never broadcast; a drain of an empty account
+     * fails with the typed asset-lock shortfall
+     * ([org.dashfoundation.dashsdk.errors.DashSdkError.PlatformWallet.AssetLockInsufficientFunds]).
+     * A stuck lock resumes via [shieldedResumeFundFromAssetLock] exactly like a
+     * BIP44-funded one.
+     *
+     * Blocks for the ~30s Halo 2 proof; the shielded note itself arrives on the
+     * next shielded sync pass, so nothing is returned.
+     *
+     * @param walletId the 32-byte wallet id.
+     * @param recipientRaw43 the 43-byte raw Orchard payment address
+     *   (11-byte diversifier + 32-byte pk_d).
+     * @param coinJoinAccountIndex the CoinJoin account whose whole balance
+     *   funds the asset lock (account 0 for every current wallet).
+     */
+    suspend fun shieldedFundFromCoinJoinDrain(
+        walletId: ByteArray,
+        recipientRaw43: ByteArray,
+        coinJoinAccountIndex: Int = 0,
+    ): Unit = teardownGate.op {
+        require(coinJoinAccountIndex >= 0) {
+            "coinJoinAccountIndex must be non-negative, got $coinJoinAccountIndex"
+        }
+        mapNativeErrors {
+            FundingNative.shieldedFundFromCoinJoinDrain(
+                managerHandle,
+                walletId,
+                coinJoinAccountIndex,
+                recipientRaw43,
+                mnemonicResolverHandle,
+            )
+        }
+    }
+
     /**
      * Shield from Platform balance (Type 15) — port of Swift's
      * `shieldedShield`. Spends [amount] credits from the wallet's

@@ -100,6 +100,31 @@ class DashSdkErrorTest {
             DashSdkError.fromNative(DashSDKException(offset + 22, "inputs reserved"))
         assertTrue(coreInsufficientFunds is DashSdkError.PlatformWallet.CoreInsufficientFunds)
 
+        // The asset-lock coin-selection shortfall (29) must reach callers as its
+        // own type rather than Generic, and must stay DISTINCT from the atomic
+        // Core-send shortfall (22) — asset-lock funding never unions across
+        // accounts, so hosts message the two differently. Its available/required
+        // duffs ride the message, which must survive verbatim.
+        val assetLockShort = DashSdkError.fromNative(
+            DashSDKException(
+                offset + 29,
+                "asset lock coin selection is short: available 18000000 duffs, " +
+                    "required 100000000 duffs",
+            ),
+        )
+        assertTrue(
+            "code 29 must not fall through to Generic",
+            assetLockShort is DashSdkError.PlatformWallet.AssetLockInsufficientFunds,
+        )
+        assertFalse(
+            "the asset-lock shortfall must not be conflated with the Core-send one",
+            assetLockShort is DashSdkError.PlatformWallet.CoreInsufficientFunds,
+        )
+        assertTrue(
+            "shortfall amounts must survive in the message",
+            assetLockShort.message!!.contains("available 18000000 duffs"),
+        )
+
         val recoveryCodes = mapOf(
             23 to DashSdkError.PlatformWallet.AssetLockNotTracked::class,
             24 to DashSdkError.PlatformWallet.AssetLockAlreadyConsumed::class,

@@ -216,6 +216,21 @@ pub enum PlatformWalletFFIResultCode {
     /// join instead of erroring. Swift mirror:
     /// `PlatformWalletResultCode.errorShutdownIncomplete`.
     ErrorShutdownIncomplete = 27,
+    /// Asset-lock coin selection came up short over the *permitted* funding
+    /// set (dashpay/platform#4073). Carries the structured
+    /// `available`/`required` duff amounts in the message string — the
+    /// by-value `PlatformWalletFFIResult` is ABI-frozen (code + message only),
+    /// so the figures ride the typed `Display` rendering or not at all.
+    ///
+    /// Distinct from [`Self::ErrorCoreInsufficientFunds`] (22), which is the
+    /// atomic Core-send selector rather than the asset-lock builder. Asset-lock
+    /// funding never unions across accounts, so this names a shortfall on the
+    /// ONE account the caller selected; a host offering another source must
+    /// name it explicitly.
+    ///
+    /// Reached by the CoinJoin → shielded migration when the mixed account
+    /// cannot cover the lock, which is why the Android binding needs it typed.
+    ErrorAssetLockInsufficientFunds = 29,
     /// A state transition could not be signed because the signer has no
     /// usable private key for the requested public key — the stored blob is
     /// missing, stranded, or written under a different Keystore/Keychain
@@ -248,7 +263,10 @@ pub enum PlatformWalletFFIResultCode {
     //
     //   27  ErrorShutdownIncomplete         MERGED on v4.2-dev (dashpay/platform#4268)
     //   28  (free — vacated by this PR)
-    //   29  ErrorAssetLockInsufficientFunds dashpay/platform#4184
+    //   29  ErrorAssetLockInsufficientFunds ALLOCATED above. Claimed by
+    //       dashpay/platform#4184, which was closed unmerged along with its
+    //       successor #4316; this PR salvages the code at its reserved number
+    //       so the ABI matches what every host mirror already documents.
     //   30  (free — vacated by this PR)
     //   31  ErrorSigningKeyUnavailable      dashpay/platform#4183, #4259
     //   32  ErrorTransactionBuild           dashpay/platform#4247, #4256
@@ -605,6 +623,16 @@ impl From<PlatformWalletError> for PlatformWalletFFIResult {
             PlatformWalletError::AssetLockFundingMismatch { .. } => {
                 PlatformWalletFFIResultCode::ErrorAssetLockFundingMismatch
             }
+            // The asset-lock coin-selection shortfall (dashpay/platform#4073).
+            // Without this arm it flattens to `ErrorUnknown` (99), hiding a
+            // typed shortfall behind the catch-all and forcing hosts to
+            // string-match the Display text. The structured
+            // `available`/`required` duff amounts still travel in the message
+            // (there are no out-params for them), but the code now lets a host
+            // branch on the shortfall without parsing text.
+            PlatformWalletError::AssetLockInsufficientFunds { .. } => {
+                PlatformWalletFFIResultCode::ErrorAssetLockInsufficientFunds
+            }
             // A quiesce/drain barrier that did not complete within budget
             // (clear/reset paths). The host must fail closed: keep its
             // callback context alive and skip any paired persistence wipe.
@@ -1076,6 +1104,59 @@ mod tests {
         }
     }
 
+    /// The asset-lock coin-selection shortfall must cross the FFI boundary as
+    /// the dedicated `ErrorAssetLockInsufficientFunds` (29) code — NOT
+    /// `ErrorUnknown` (99) as it did before this arm existed
+    /// (dashpay/platform#4073) — and its structured `available`/`required`
+    /// duffs must survive verbatim in the message so hosts can parse the
+    /// amounts.
+    #[test]
+    fn asset_lock_insufficient_funds_maps_to_dedicated_code() {
+        let err = PlatformWalletError::AssetLockInsufficientFunds {
+            available: 18_000_000,
+            required: 100_000_000,
+        };
+        let rendered = err.to_string();
+        // Guard the exact text hosts (dash-wallet) substring-match on.
+        assert!(
+            rendered.contains("asset lock coin selection is short"),
+            "shortfall Display text changed — coordinate dash-wallet's matcher \
+             (rendered: {rendered})"
+        );
+        let result: PlatformWalletFFIResult = err.into();
+        assert_eq!(
+            result.code,
+            PlatformWalletFFIResultCode::ErrorAssetLockInsufficientFunds,
+            "must not flatten to ErrorUnknown(99) (rendered: {rendered})"
+        );
+        assert_ne!(
+            result.code as i32,
+            PlatformWalletFFIResultCode::ErrorUnknown as i32
+        );
+        assert!(!result.message.is_null());
+        let msg = unsafe { std::ffi::CStr::from_ptr(result.message) }
+            .to_string_lossy()
+            .into_owned();
+        assert_eq!(
+            msg, rendered,
+            "structured available/required duffs must survive the FFI boundary verbatim"
+        );
+    }
+
+    /// The numeric value of `ErrorAssetLockInsufficientFunds` is ABI, mirrored
+    /// by hand in the Swift and Kotlin host enums. Pin it so a future
+    /// renumbering of the surrounding block cannot silently re-point a host's
+    /// shortfall branch at some other error.
+    #[test]
+    fn asset_lock_insufficient_funds_code_is_pinned_at_29() {
+        assert_eq!(
+            PlatformWalletFFIResultCode::ErrorAssetLockInsufficientFunds as i32,
+            29,
+            "code 29 is reserved for the asset-lock shortfall in the FFI \
+             error-code registry; hosts mirror the number, not the name"
+        );
+    }
+
     /// `WalletAlreadyExists` maps to the dedicated
     /// `ErrorWalletAlreadyExists` FFI code rather than flattening to
     /// `ErrorUnknown`, so multi-network wallet create/enable callers can

@@ -252,6 +252,36 @@ pub enum PlatformWalletError {
         actual_identity_index: u32,
     },
 
+    /// Asset-lock coin selection came up short, so a host (and ultimately the
+    /// wallet UI) can render a precise shortfall instead of a stringly-typed
+    /// "Insufficient funds" message (dashpay/platform#4073).
+    ///
+    /// The `available` figure reflects the single funds account the caller
+    /// selected — the unmixed BIP44 account by default, or an explicit account
+    /// such as CoinJoin. A shortfall here means that *one* account is short:
+    /// asset-lock funding never unions across accounts, so a different source
+    /// must be named explicitly rather than combined automatically.
+    ///
+    /// Distinct from [`CoreInsufficientFunds`] / [`CorePooledInsufficientFunds`],
+    /// which belong to the atomic Core-send selector rather than the asset-lock
+    /// builder, and which carry `Option` amounts because a pooled send may not
+    /// know them. The asset-lock builder always has concrete figures: the
+    /// key-wallet shortfall errors carry their own, and the empty-candidate-set
+    /// case is reported as `available: 0` against the requested target.
+    ///
+    /// On a *drain* build (whole-account funding, e.g. the CoinJoin → shielded
+    /// migration) the requested target is the zero credit-output placeholder
+    /// that key-wallet rewrites to `Σ inputs − fee`, so an empty account
+    /// surfaces here as `available: 0, required: 0` — the "this account has
+    /// nothing to drain" signal. The real floor for a drain is the Type 18 pool
+    /// fee, enforced downstream against the built payload once the lock value
+    /// is known.
+    #[error(
+        "asset lock coin selection is short: available {available} duffs, \
+         required {required} duffs"
+    )]
+    AssetLockInsufficientFunds { available: u64, required: u64 },
+
     #[error("SDK error: {0}")]
     Sdk(#[from] dash_sdk::Error),