diff --git a/src/main/tjava/com/r35157/libs/jupiter/perps/JupiterPerpsService.tjava b/src/main/tjava/com/r35157/libs/jupiter/perps/JupiterPerpsService.tjava
index b45e2e7..dd72980 100644
--- a/src/main/tjava/com/r35157/libs/jupiter/perps/JupiterPerpsService.tjava
+++ b/src/main/tjava/com/r35157/libs/jupiter/perps/JupiterPerpsService.tjava
@@ -1,19 +1,20 @@
 package com.r35157.libs.jupiter.perps;
 
+import com.r35157.libs.solana.SolanaSignedTransaction;
+import com.r35157.libs.solana.SolanaUnsignedTransaction;
 import org.jetbrains.annotations.NotNull;
 import org.jetbrains.annotations.Nullable;
 
 import java.io.IOException;
+import java.math.BigDecimal;
 import java.util.Set;
 
 /**
- * Service for reading Jupiter Perps data.
+ * Service for reading Jupiter Perps data and constructing and executing
+ * Jupiter Perps transactions.
  *
- * <p>This service is read-only. It does not open, close, modify, or sign transactions
- * for Jupiter Perpetual Contracts.</p>
- *
- * <p>NOTICE: The first supported operation is reading a known Jupiter Perps position account
- * and returning its decoded position data.</p>
+ * <p>This service does not sign transactions. A compatible wallet is
+ * required to sign a constructed transaction before it can be executed.</p>
  */
 public interface JupiterPerpsService {
     /**
@@ -45,4 +46,61 @@ public interface JupiterPerpsService {
      */
     @NotNull Set<JupiterPerpsPosition> getOpenPositions(@NotNull ΩSolanaWalletIdΩ owner)
             throws IOException, InterruptedException;
+
+    /**
+     * Constructs an unsigned Solana transaction for opening or increasing
+     * a Jupiter Perps position.
+     *
+     * <p>The transaction is constructed for the supplied wallet, traded asset,
+     * position direction, USDC collateral amount, position-size delta, and
+     * slippage limit.</p>
+     *
+     * <p>This method does not sign or submit the transaction and therefore does
+     * not modify blockchain state. The returned transaction must be signed by
+     * the supplied wallet and submitted separately.</p>
+     *
+     * @param owner the wallet that owns or will own the position
+     * @param tradedTokenMint the mint address of the asset being traded
+     * @param direction whether the position is long or short
+     * @param inputTokenAmount the amount of USDC to supply as collateral
+     * @param sizeUsdDelta the requested increase in position size, denominated in USD
+     * @param maxSlippageBps the maximum accepted slippage, in basis points
+     * @return the complete unsigned Solana transaction
+     * @throws IllegalArgumentException if an amount, mint, or slippage value is invalid
+     * @throws IOException if Jupiter cannot construct the transaction or its response
+     *                     cannot be decoded
+     * @throws InterruptedException if the calling thread is interrupted while
+     *                              communicating with Jupiter
+     */
+    @NotNull SolanaUnsignedTransaction buildPositionIncreaseTransaction(
+            @NotNull ΩSolanaWalletIdΩ owner,
+            @NotNull ΩSPLMintAddressΩ tradedTokenMint,
+            @NotNull JupiterPerpsPositionDirection direction,
+            @NotNull ΩUSDCAmountΩ inputTokenAmount,
+            @NotNull ΩUSDCAmountΩ sizeUsdDelta,
+            int maxSlippageBps
+    ) throws IOException, InterruptedException;
+
+    /**
+     * Executes a signed Jupiter Perps position-increase transaction.
+     *
+     * <p>The supplied transaction must previously have been constructed by
+     * {@link #buildPositionIncreaseTransaction} and signed by its required
+     * Solana wallet.</p>
+     *
+     * <p>Unlike the build method, this operation submits the transaction and
+     * may therefore modify blockchain state.</p>
+     *
+     * @param transaction the complete signed position-increase transaction
+     * @return the Solana transaction signature
+     * @throws IllegalArgumentException if the transaction is missing or blank
+     * @throws IOException if Jupiter rejects the transaction or its response
+     *                     cannot be decoded
+     * @throws InterruptedException if the calling thread is interrupted while
+     *                              communicating with Jupiter
+     */
+    @NotNull
+    ΩSolanaTransactionSignatureΩ executePositionIncreaseTransaction(
+            @NotNull SolanaSignedTransaction transaction
+    ) throws IOException, InterruptedException;
 }
\ No newline at end of file
diff --git a/src/main/tjava/com/r35157/libs/jupiter/perps/impl/anchoridl/AnchorIdlJupiterPerpsServiceImpl.tjava b/src/main/tjava/com/r35157/libs/jupiter/perps/impl/anchoridl/AnchorIdlJupiterPerpsServiceImpl.tjava
index 818e08e..2f15c47 100644
--- a/src/main/tjava/com/r35157/libs/jupiter/perps/impl/anchoridl/AnchorIdlJupiterPerpsServiceImpl.tjava
+++ b/src/main/tjava/com/r35157/libs/jupiter/perps/impl/anchoridl/AnchorIdlJupiterPerpsServiceImpl.tjava
@@ -1,11 +1,19 @@
 package com.r35157.libs.jupiter.perps.impl.anchoridl;
 
+import com.fasterxml.jackson.databind.ObjectMapper;
 import com.r35157.libs.jupiter.perps.JupiterPerpsPosition;
 import com.r35157.libs.jupiter.perps.JupiterPerpsPositionDirection;
 import com.r35157.libs.jupiter.perps.JupiterPerpsService;
+import com.r35157.libs.jupiter.perps.protocol.ExecuteTransactionRequest;
+import com.r35157.libs.jupiter.perps.protocol.ExecuteTransactionResponse;
+import com.r35157.libs.jupiter.perps.protocol.IncreasePositionRequest;
+import com.r35157.libs.jupiter.perps.protocol.IncreasePositionResponse;
+import com.r35157.libs.jupiter.perps.protocol.TransactionMetadata;
 import com.r35157.libs.solana.SolanaAccountInfo;
 import com.r35157.libs.solana.SolanaBlockChain;
 import com.r35157.libs.solana.SolanaProgramAccountMemcmpFilter;
+import com.r35157.libs.solana.SolanaSignedTransaction;
+import com.r35157.libs.solana.SolanaUnsignedTransaction;
 import com.r35157.libs.valuetypes.basic.MoneyAmount;
 import com.r35157.libs.valuetypes.basic.WellKnownCurrencyTypes;
 import org.jetbrains.annotations.NotNull;
@@ -15,6 +23,10 @@ import java.io.IOException;
 import java.math.BigDecimal;
 import java.math.BigInteger;
 import java.math.RoundingMode;
+import java.net.URI;
+import java.net.http.HttpClient;
+import java.net.http.HttpRequest;
+import java.net.http.HttpResponse;
 import java.util.HashSet;
 import java.util.Set;
 
@@ -99,6 +111,88 @@ public class AnchorIdlJupiterPerpsServiceImpl implements JupiterPerpsService {
         return Set.copyOf(positions);
     }
 
+    @Override
+    public @NotNull SolanaUnsignedTransaction buildPositionIncreaseTransaction(
+            @NotNull ΩSolanaWalletIdΩ owner,
+            @NotNull ΩSPLMintAddressΩ tradedTokenMint,
+            @NotNull JupiterPerpsPositionDirection direction,
+            @NotNull ΩUSDCAmountΩ inputTokenAmount,
+            @NotNull ΩUSDCAmountΩ sizeUsdDelta,
+            int maxSlippageBps
+    ) throws IOException, InterruptedException {
+        IncreasePositionRequest request = buildIncreasePositionRequest(
+                owner,
+                tradedTokenMint,
+                direction,
+                inputTokenAmount,
+                sizeUsdDelta,
+                maxSlippageBps
+        );
+
+        IncreasePositionResponse response = requestPositionIncrease(request);
+        TransactionMetadata metadata = response.txMetadata();
+
+        if (response.serializedTxBase64() == null
+                || response.serializedTxBase64().isBlank()) {
+            throw new IOException(
+                    "Jupiter Perps response did not contain a serialized transaction"
+            );
+        }
+
+        if (metadata == null) {
+            throw new IOException(
+                    "Jupiter Perps response did not contain transaction metadata"
+            );
+        }
+
+        try {
+            SolanaUnsignedTransaction utx = new SolanaUnsignedTransaction(
+                    response.serializedTxBase64(),
+                    metadata.blockhash(),
+                    Long.parseLong(metadata.lastValidBlockHeight())
+            );
+
+            return utx;
+        } catch (NumberFormatException e) {
+            throw new IOException(
+                    "Invalid lastValidBlockHeight returned by Jupiter: "
+                            + metadata.lastValidBlockHeight(),
+                    e
+            );
+        }
+    }
+
+    @Override
+    public @NotNull ΩSolanaTransactionSignatureΩ
+    executePositionIncreaseTransaction(
+            @NotNull SolanaSignedTransaction transaction
+    ) throws IOException, InterruptedException {
+        if (transaction.serializedTransaction() == null
+                || transaction.serializedTransaction().isBlank()) {
+            throw new IllegalArgumentException(
+                    "Signed transaction must not be blank"
+            );
+        }
+
+        ExecuteTransactionRequest request =
+                new ExecuteTransactionRequest(
+                        "increase-position",
+                        transaction.serializedTransaction()
+                );
+
+        ExecuteTransactionResponse response =
+                requestTransactionExecution(request);
+
+        if (response.txid() == null || response.txid().isBlank()) {
+            throw new IOException(
+                    "Jupiter transaction execution response did not "
+                            + "contain a transaction signature"
+            );
+        }
+
+        return response.txid();
+    }
+
     private JupiterPerpsPosition buildPosition(
             ΩJupiterPerpsPositionAccountΩ positionAccount,
             JupiterPerpsPositionInfo perpsPositionInfo
@@ -261,11 +355,191 @@ public class AnchorIdlJupiterPerpsServiceImpl implements JupiterPerpsService {
         throw new IllegalArgumentException("Unsupported Jupiter Perps position direction: " + direction);
     }
 
+    private static IncreasePositionRequest buildIncreasePositionRequest(
+            ΩSolanaWalletIdΩ owner,
+            ΩSPLMintAddressΩ tradedTokenMint,
+            JupiterPerpsPositionDirection direction,
+            ΩUSDCAmountΩ inputTokenAmount,
+            ΩUSDCAmountΩ sizeUsdDelta,
+            int maxSlippageBps
+    ) {
+        if (inputTokenAmount.signum() <= 0) {
+            throw new IllegalArgumentException(
+                    "Input token amount must be greater than zero: " + inputTokenAmount
+            );
+        }
+
+        if (sizeUsdDelta.signum() < 0) {
+            throw new IllegalArgumentException(
+                    "Position size delta must not be negative: " + sizeUsdDelta
+            );
+        }
+
+        if (maxSlippageBps < 0 || maxSlippageBps > BASIS_POINTS_DIVISOR) {
+            throw new IllegalArgumentException(
+                    "Maximum slippage must be between 0 and "
+                            + BASIS_POINTS_DIVISOR
+                            + " basis points: "
+                            + maxSlippageBps
+            );
+        }
+
+        IncreasePositionRequest request = new IncreasePositionRequest(
+                toProtocolAsset(tradedTokenMint),
+                "USDC",
+                toMicroAmount(inputTokenAmount),
+                toProtocolSide(direction),
+                Integer.toString(maxSlippageBps),
+                toMicroAmount(sizeUsdDelta),
+                owner
+        );
+
+        return request;
+    }
+
+    private static String toProtocolAsset(ΩSPLMintAddressΩ tradedTokenMint) {
+        if (SOL_MINT.equals(tradedTokenMint)) {
+            return "SOL";
+        }
+
+        if (BTC_MINT.equals(tradedTokenMint)) {
+            return "BTC";
+        }
+
+        if (ETH_MINT.equals(tradedTokenMint)) {
+            return "ETH";
+        }
+
+        throw new IllegalArgumentException(
+                "Unsupported Jupiter Perps traded-token mint: " + tradedTokenMint
+        );
+    }
+
+    private static String toProtocolSide(
+            JupiterPerpsPositionDirection direction
+    ) {
+        return switch (direction) {
+            case LONG -> "long";
+            case SHORT -> "short";
+        };
+    }
+
+    private static String toMicroAmount(BigDecimal amount) {
+        return amount
+                .movePointRight(USDC_DECIMALS)
+                .toBigIntegerExact()
+                .toString();
+    }
+
+    private static IncreasePositionResponse requestPositionIncrease(
+            IncreasePositionRequest request
+    ) throws IOException, InterruptedException {
+        String requestJson = OBJECT_MAPPER.writeValueAsString(request);
+
+        HttpRequest httpRequest = HttpRequest.newBuilder()
+                .uri(INCREASE_POSITION_ENDPOINT)
+                .header("Content-Type", "application/json")
+                .header("Accept", "application/json")
+                .header("x-client-platform", "nenjim-hub")
+                .POST(HttpRequest.BodyPublishers.ofString(requestJson))
+                .build();
+
+        HttpResponse<String> httpResponse = HTTP_CLIENT.send(
+                httpRequest,
+                HttpResponse.BodyHandlers.ofString()
+        );
+
+        if (httpResponse.statusCode() < 200 || httpResponse.statusCode() >= 300) {
+            throw new IOException(
+                    "Jupiter Perps increase-position request failed with HTTP "
+                            + httpResponse.statusCode()
+                            + ": "
+                            + httpResponse.body()
+            );
+        }
+
+        IncreasePositionResponse response = OBJECT_MAPPER.readValue(
+                httpResponse.body(),
+                IncreasePositionResponse.class
+        );
+
+        TransactionMetadata metadata = response.txMetadata();
+
+        if (metadata.blockhash() == null || metadata.blockhash().isBlank()) {
+            String errorMsg = "Jupiter Perps response did not contain a blockhash";
+            throw new IOException(errorMsg);
+        }
+
+        long lastValidBlockHeight;
+
+        try {
+            lastValidBlockHeight =
+                    Long.parseLong(metadata.lastValidBlockHeight());
+        } catch (NumberFormatException e) {
+            String errorMsg = "Invalid lastValidBlockHeight returned by Jupiter: " + metadata.lastValidBlockHeight();
+            throw new IOException(errorMsg, e);
+        }
+
+        if (lastValidBlockHeight <= 0) {
+            String errorMsg = "Invalid lastValidBlockHeight returned by Jupiter: " + lastValidBlockHeight;
+            throw new IOException(errorMsg);
+        }
+
+        return response;
+    }
+
+    private static ExecuteTransactionResponse requestTransactionExecution(
+            ExecuteTransactionRequest request
+    ) throws IOException, InterruptedException {
+        String requestJson =
+                OBJECT_MAPPER.writeValueAsString(request);
+
+        HttpRequest httpRequest = HttpRequest.newBuilder()
+                .uri(EXECUTE_TRANSACTION_ENDPOINT)
+                .header("Content-Type", "application/json")
+                .header("Accept", "application/json")
+                .header("x-client-platform", "nenjim-hub")
+                .POST(HttpRequest.BodyPublishers.ofString(requestJson))
+                .build();
+
+        HttpResponse<String> httpResponse = HTTP_CLIENT.send(
+                httpRequest,
+                HttpResponse.BodyHandlers.ofString()
+        );
+
+        if (httpResponse.statusCode() < 200
+                || httpResponse.statusCode() >= 300) {
+            throw new IOException(
+                    "Jupiter transaction execution failed with HTTP "
+                            + httpResponse.statusCode()
+                            + ": "
+                            + httpResponse.body()
+            );
+        }
+
+        return OBJECT_MAPPER.readValue(
+                httpResponse.body(),
+                ExecuteTransactionResponse.class
+        );
+    }
+
+    private static final ΩSPLMintAddressΩ SOL_MINT = "So11111111111111111111111111111111111111112";
+    private static final ΩSPLMintAddressΩ BTC_MINT = "3NZ9JMVBmGAqocybic2c7LQCJScmgsAZ6vQqTDzcqmJh";
+    private static final ΩSPLMintAddressΩ ETH_MINT = "7vfCXTUXx5WJV5JADk17DUJ4ksgau7utNKj4b963voxs";
+
+    private static final URI EXECUTE_TRANSACTION_ENDPOINT =
+            URI.create(
+                    "https://perps-api.jup.ag/v2/transaction/execute"
+            );
+
+    private static final ΩJupiterPerpsProgramIdΩ JUPITER_PERPS_PROGRAM_ID = "PERPHjGBqRHArX4DySjwM6UJHiR3sWAatqfdBS2qQJu";
+
+    private static final URI INCREASE_POSITION_ENDPOINT = URI.create("https://perps-api.jup.ag/v2/positions/increase");
+    private static final HttpClient HTTP_CLIENT = HttpClient.newHttpClient();
+    private static final ObjectMapper OBJECT_MAPPER = new ObjectMapper();
     private static final long RATE_POWER = 1_000_000_000L;
     private static final int CLOSE_FEE_BPS = 6;
     private static final int BASIS_POINTS_DIVISOR = 10_000;
-    private static final ΩJupiterPerpsProgramIdΩ JUPITER_PERPS_PROGRAM_ID =
-            "PERPHjGBqRHArX4DySjwM6UJHiR3sWAatqfdBS2qQJu";
     private static final int POSITION_OWNER_OFFSET = 8;
     private static final int MAX_LEVERAGE = 500;
     private static final int USDC_DECIMALS = 6;
diff --git a/src/main/tjava/com/r35157/libs/jupiter/perps/protocol/ExecuteTransactionRequest.tjava b/src/main/tjava/com/r35157/libs/jupiter/perps/protocol/ExecuteTransactionRequest.tjava
new file mode 100644
index 0000000..856bad4
--- /dev/null
+++ b/src/main/tjava/com/r35157/libs/jupiter/perps/protocol/ExecuteTransactionRequest.tjava
@@ -0,0 +1,14 @@
+package com.r35157.libs.jupiter.perps.protocol;
+
+/**
+ * Jupiter Perps protocol request for executing a signed transaction.
+ *
+ * @param action the Jupiter transaction action
+ * @param serializedTxBase64 the complete signed Solana transaction,
+ *                           encoded as Base64
+ */
+public record ExecuteTransactionRequest(
+        String action,
+        String serializedTxBase64
+) {
+}
\ No newline at end of file
diff --git a/src/main/tjava/com/r35157/libs/jupiter/perps/protocol/ExecuteTransactionResponse.tjava b/src/main/tjava/com/r35157/libs/jupiter/perps/protocol/ExecuteTransactionResponse.tjava
new file mode 100644
index 0000000..5b35e18
--- /dev/null
+++ b/src/main/tjava/com/r35157/libs/jupiter/perps/protocol/ExecuteTransactionResponse.tjava
@@ -0,0 +1,14 @@
+package com.r35157.libs.jupiter.perps.protocol;
+
+import com.fasterxml.jackson.annotation.JsonIgnoreProperties;
+
+/**
+ * Relevant fields returned by Jupiter after executing a transaction.
+ *
+ * @param txid the Solana transaction signature
+ */
+@JsonIgnoreProperties(ignoreUnknown = true)
+public record ExecuteTransactionResponse(
+        String txid
+) {
+}
\ No newline at end of file
diff --git a/src/main/tjava/com/r35157/libs/jupiter/perps/protocol/IncreasePositionRequest.tjava b/src/main/tjava/com/r35157/libs/jupiter/perps/protocol/IncreasePositionRequest.tjava
new file mode 100644
index 0000000..ac3b9fe
--- /dev/null
+++ b/src/main/tjava/com/r35157/libs/jupiter/perps/protocol/IncreasePositionRequest.tjava
@@ -0,0 +1,30 @@
+package com.r35157.libs.jupiter.perps.protocol;
+
+/**
+ * Jupiter Perps protocol request for constructing an unsigned
+ * position-increase transaction.
+ *
+ * @param asset the Jupiter Perps market symbol, such as {@code SOL},
+ *              {@code BTC}, or {@code ETH}
+ * @param inputToken the symbol of the token supplied as collateral,
+ *                   currently {@code USDC}
+ * @param inputTokenAmount the input-token amount in raw chain units,
+ *                         encoded as a decimal string
+ * @param side the position direction in Jupiter protocol format:
+ *             {@code long} or {@code short}
+ * @param maxSlippageBps the maximum accepted slippage in basis points,
+ *                       encoded as a decimal string
+ * @param sizeUsdDelta the requested position-size increase in micro-USD,
+ *                     encoded as a decimal string
+ * @param walletAddress the Solana wallet that owns or will own the position
+ */
+public record IncreasePositionRequest(
+        String asset,
+        String inputToken,
+        String inputTokenAmount,
+        String side,
+        String maxSlippageBps,
+        String sizeUsdDelta,
+        String walletAddress
+) {
+}
diff --git a/src/main/tjava/com/r35157/libs/jupiter/perps/protocol/IncreasePositionResponse.tjava b/src/main/tjava/com/r35157/libs/jupiter/perps/protocol/IncreasePositionResponse.tjava
new file mode 100644
index 0000000..45ef744
--- /dev/null
+++ b/src/main/tjava/com/r35157/libs/jupiter/perps/protocol/IncreasePositionResponse.tjava
@@ -0,0 +1,25 @@
+package com.r35157.libs.jupiter.perps.protocol;
+
+import com.fasterxml.jackson.annotation.JsonIgnoreProperties;
+
+/**
+ * Relevant fields returned by Jupiter after constructing an unsigned
+ * position-increase transaction.
+ *
+ * <p>Additional response fields that are not required by the current
+ * implementation are ignored during decoding.</p>
+ *
+ * @param positionPubkey the Solana account address of the position that
+ *                       will be opened or increased
+ * @param serializedTxBase64 the complete unsigned Solana transaction,
+ *                           encoded as Base64
+ * @param txMetadata metadata describing the transaction's blockhash
+ *                   and validity period
+ */
+@JsonIgnoreProperties(ignoreUnknown = true)
+public record IncreasePositionResponse(
+        String positionPubkey,
+        String serializedTxBase64,
+        TransactionMetadata txMetadata
+) {
+}
diff --git a/src/main/tjava/com/r35157/libs/jupiter/perps/protocol/TransactionMetadata.tjava b/src/main/tjava/com/r35157/libs/jupiter/perps/protocol/TransactionMetadata.tjava
new file mode 100644
index 0000000..7914302
--- /dev/null
+++ b/src/main/tjava/com/r35157/libs/jupiter/perps/protocol/TransactionMetadata.tjava
@@ -0,0 +1,17 @@
+package com.r35157.libs.jupiter.perps.protocol;
+
+import com.fasterxml.jackson.annotation.JsonIgnoreProperties;
+
+/**
+ * Validity metadata for a Solana transaction constructed by Jupiter.
+ *
+ * @param blockhash the recent Solana blockhash embedded in the transaction
+ * @param lastValidBlockHeight the last block height at which the transaction
+ *                             may be processed, encoded as a decimal string
+ */
+@JsonIgnoreProperties(ignoreUnknown = true)
+public record TransactionMetadata(
+        String blockhash,
+        String lastValidBlockHeight
+) {
+}
diff --git a/src/main/tjava/com/r35157/libs/solana/SolanaUnsignedTransaction.tjava b/src/main/tjava/com/r35157/libs/solana/SolanaUnsignedTransaction.tjava
new file mode 100644
index 0000000..4612d68
--- /dev/null
+++ b/src/main/tjava/com/r35157/libs/solana/SolanaUnsignedTransaction.tjava
@@ -0,0 +1,15 @@
+package com.r35157.libs.solana;
+
+/**
+ * A serialized Solana transaction that has not yet been signed or submitted.
+ *
+ * @param serializedTransaction the complete Base64 encoded Solana transaction
+ * @param blockhash the recent blockhash used by the transaction
+ * @param lastValidBlockHeight the last block height at which the transaction is valid
+ */
+public record SolanaUnsignedTransaction(
+        ΩBase64StringΩ serializedTransaction,
+        ΩSolanaBlockhashΩ blockhash,
+        long lastValidBlockHeight
+) {
+}
\ No newline at end of file