initial commit

2026-03-24 17:41:26 -04:00
commit 456913cea0
33 changed files with 2708 additions and 0 deletions
--- a/.gitattributes
+++ b/.gitattributes
@@ -0,0 +1,5 @@
+# Disable autocrlf on generated files, they always generate with LF
+# Add any extra files or paths here to make git stop saying they
+# are changed when only line endings change.
+src/generated/**/.cache/* text eol=lf
+src/generated/**/*.json text eol=lf
--- a/.github/workflows/build.yml
+++ b/.github/workflows/build.yml
@@ -0,0 +1,30 @@
+name: Build
+
+on: [push, pull_request]
+
+jobs:
+  build:
+    runs-on: ubuntu-latest
+    steps:
+      - name: Checkout repository
+        uses: actions/checkout@v4
+        with:
+          fetch-depth: 0
+          fetch-tags: true
+
+      - name: Setup JDK 21
+        uses: actions/setup-java@v4
+        with:
+          java-version: '21'
+          distribution: 'temurin'
+
+      - name: Setup Gradle
+        uses: gradle/actions/setup-gradle@v4
+
+      # This is needed to be able to run ./gradlew below
+      # You can run `git update-index --chmod +x gradlew` then remove this step.
+      - name: Make Gradle wrapper executable
+        run: chmod +x ./gradlew
+
+      - name: Build with Gradle
+        run: ./gradlew build
--- a/.gitignore
+++ b/.gitignore
@@ -0,0 +1,41 @@
+### Gradle ###
+.gradle
+build/
+!gradle/wrapper/gradle-wrapper.jar
+!**/src/**/build/
+
+### IntelliJ IDEA ###
+.idea/
+*.iws
+*.iml
+*.ipr
+out/
+!**/src/**/out/
+
+.run/
+
+### Eclipse ###
+.apt_generated
+.classpath
+.eclipse/
+.factorypath
+.project
+.settings
+.springBeans
+.sts4-cache
+bin/
+!**/src/**/bin/
+
+### VS Code ###
+.vscode/
+
+### Mac OS ###
+.DS_Store
+
+### Minecraft Modding ###
+run/
+!**/src/**/run/
+**/src/generated/**/.cache/
+repo/
+!**/src/**/repo/
+/.gradle-user-home/
--- a/README.md
+++ b/README.md
@@ -0,0 +1,25 @@
+
+Installation information
+=======
+
+This template repository can be directly cloned to get you started with a new
+mod. Simply create a new repository cloned from this one, by following the
+instructions provided by [GitHub](https://docs.github.com/en/repositories/creating-and-managing-repositories/creating-a-repository-from-a-template).
+
+Once you have your clone, simply open the repository in the IDE of your choice. The usual recommendation for an IDE is either IntelliJ IDEA or Eclipse.
+
+If at any point you are missing libraries in your IDE, or you've run into problems you can
+run `gradlew --refresh-dependencies` to refresh the local cache. `gradlew clean` to reset everything 
+{this does not affect your code} and then start the process again.
+
+Mapping Names:
+============
+By default, the MDK is configured to use the official mapping names from Mojang for methods and fields 
+in the Minecraft codebase. These names are covered by a specific license. All modders should be aware of this
+license. For the latest license text, refer to the mapping file itself, or the reference copy here:
+https://github.com/NeoForged/NeoForm/blob/main/Mojang.md
+
+Additional Resources: 
+==========
+Community Documentation: https://docs.neoforged.net/  
+NeoForged Discord: https://discord.neoforged.net/
--- a/TEMPLATE_LICENSE.txt
+++ b/TEMPLATE_LICENSE.txt
@@ -0,0 +1,24 @@
+MIT License
+
+Copyright (c) 2023 NeoForged project
+
+This license applies to the template files as supplied by github.com/NeoForged/MDK
+
+
+Permission is hereby granted, free of charge, to any person obtaining a copy
+of this software and associated documentation files (the "Software"), to deal
+in the Software without restriction, including without limitation the rights
+to use, copy, modify, merge, publish, distribute, sublicense, and/or sell
+copies of the Software, and to permit persons to whom the Software is
+furnished to do so, subject to the following conditions:
+
+The above copyright notice and this permission notice shall be included in all
+copies or substantial portions of the Software.
+
+THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR
+IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,
+FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL THE
+AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER
+LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM,
+OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN THE
+SOFTWARE.
--- a/build.gradle
+++ b/build.gradle
@@ -0,0 +1,192 @@
+plugins {
+    id 'java-library'
+    id 'maven-publish'
+    id 'net.neoforged.moddev' version '2.0.140'
+    id 'idea'
+}
+
+tasks.named('wrapper', Wrapper).configure {
+    // Define wrapper values here so as to not have to always do so when updating gradlew.properties.
+    // Switching this to Wrapper.DistributionType.ALL will download the full gradle sources that comes with
+    // documentation attached on cursor hover of gradle classes and methods. However, this comes with increased
+    // file size for Gradle. If you do switch this to ALL, run the Gradle wrapper task twice afterwards.
+    // (Verify by checking gradle/wrapper/gradle-wrapper.properties to see if distributionUrl now points to `-all`)
+    distributionType = Wrapper.DistributionType.BIN
+}
+
+version = mod_version
+group = mod_group_id
+
+sourceSets.main.resources {
+    // Include resources generated by data generators.
+    srcDir('src/generated/resources')
+
+    // Exclude common development only resources from finalized outputs
+    exclude("**/*.bbmodel") // BlockBench project files
+    exclude("src/generated/**/.cache") // datagen cache files
+}
+
+repositories {
+    // Add here additional repositories if required by some of the dependencies below.
+}
+
+base {
+    archivesName = mod_id
+}
+
+// Mojang ships Java 21 to end users in 1.21.1, so mods should target Java 21.
+java.toolchain.languageVersion = JavaLanguageVersion.of(21)
+
+neoForge {
+    // Specify the version of NeoForge to use.
+    version = project.neo_version
+
+    parchment {
+        mappingsVersion = project.parchment_mappings_version
+        minecraftVersion = project.parchment_minecraft_version
+    }
+
+    // This line is optional. Access Transformers are automatically detected
+    // accessTransformers = project.files('src/main/resources/META-INF/accesstransformer.cfg')
+
+    // Default run configurations.
+    // These can be tweaked, removed, or duplicated as needed.
+    runs {
+        client {
+            client()
+
+            // Comma-separated list of namespaces to load gametests from. Empty = all namespaces.
+            systemProperty 'neoforge.enabledGameTestNamespaces', project.mod_id
+        }
+
+        server {
+            server()
+            programArgument '--nogui'
+            systemProperty 'neoforge.enabledGameTestNamespaces', project.mod_id
+        }
+
+        // This run config launches GameTestServer and runs all registered gametests, then exits.
+        // By default, the server will crash when no gametests are provided.
+        // The gametest system is also enabled by default for other run configs under the /test command.
+        gameTestServer {
+            type = "gameTestServer"
+            systemProperty 'neoforge.enabledGameTestNamespaces', project.mod_id
+        }
+
+        data {
+            data()
+
+            // example of overriding the workingDirectory set in configureEach above, uncomment if you want to use it
+            // gameDirectory = project.file('run-data')
+
+            // Specify the modid for data generation, where to output the resulting resource, and where to look for existing resources.
+            programArguments.addAll '--mod', project.mod_id, '--all', '--output', file('src/generated/resources/').getAbsolutePath(), '--existing', file('src/main/resources/').getAbsolutePath()
+        }
+
+        // applies to all the run configs above
+        configureEach {
+            // Recommended logging data for a userdev environment
+            // The markers can be added/remove as needed separated by commas.
+            // "SCAN": For mods scan.
+            // "REGISTRIES": For firing of registry events.
+            // "REGISTRYDUMP": For getting the contents of all registries.
+            systemProperty 'forge.logging.markers', 'REGISTRIES'
+
+            // Recommended logging level for the console
+            // You can set various levels here.
+            // Please read: https://stackoverflow.com/questions/2031163/when-to-use-the-different-log-levels
+            logLevel = org.slf4j.event.Level.DEBUG
+        }
+    }
+
+    mods {
+        // define mod <-> source bindings
+        // these are used to tell the game which sources are for which mod
+        // multi mod projects should define one per mod
+        "${mod_id}" {
+            sourceSet(sourceSets.main)
+        }
+    }
+}
+
+// Sets up a dependency configuration called 'localRuntime'.
+// This configuration should be used instead of 'runtimeOnly' to declare
+// a dependency that will be present for runtime testing but that is
+// "optional", meaning it will not be pulled by dependents of this mod.
+configurations {
+    runtimeClasspath.extendsFrom localRuntime
+}
+
+dependencies {
+    // Example optional mod dependency with JEI
+    // The JEI API is declared for compile time use, while the full JEI artifact is used at runtime
+    // compileOnly "mezz.jei:jei-${mc_version}-common-api:${jei_version}"
+    // compileOnly "mezz.jei:jei-${mc_version}-neoforge-api:${jei_version}"
+    // We add the full version to localRuntime, not runtimeOnly, so that we do not publish a dependency on it
+    // localRuntime "mezz.jei:jei-${mc_version}-neoforge:${jei_version}"
+
+    // Example mod dependency using a mod jar from ./libs with a flat dir repository
+    // This maps to ./libs/coolmod-${mc_version}-${coolmod_version}.jar
+    // The group id is ignored when searching -- in this case, it is "blank"
+    // implementation "blank:coolmod-${mc_version}:${coolmod_version}"
+
+    // Example mod dependency using a file as dependency
+    // implementation files("libs/coolmod-${mc_version}-${coolmod_version}.jar")
+
+    // Example project dependency using a sister or child project:
+    // implementation project(":myproject")
+
+    // For more info:
+    // http://www.gradle.org/docs/current/userguide/artifact_dependencies_tutorial.html
+    // http://www.gradle.org/docs/current/userguide/dependency_management.html
+}
+
+// This block of code expands all declared replace properties in the specified resource targets.
+// A missing property will result in an error. Properties are expanded using ${} Groovy notation.
+var generateModMetadata = tasks.register("generateModMetadata", ProcessResources) {
+    var replaceProperties = [
+            minecraft_version      : minecraft_version,
+            minecraft_version_range: minecraft_version_range,
+            neo_version            : neo_version,
+            loader_version_range   : loader_version_range,
+            mod_id                 : mod_id,
+            mod_name               : mod_name,
+            mod_license            : mod_license,
+            mod_version            : mod_version,
+    ]
+    inputs.properties replaceProperties
+    expand replaceProperties
+    from "src/main/templates"
+    into "build/generated/sources/modMetadata"
+}
+// Include the output of "generateModMetadata" as an input directory for the build
+// this works with both building through Gradle and the IDE.
+sourceSets.main.resources.srcDir generateModMetadata
+// To avoid having to run "generateModMetadata" manually, make it run on every project reload
+neoForge.ideSyncTask generateModMetadata
+
+// Example configuration to allow publishing using the maven-publish plugin
+publishing {
+    publications {
+        register('mavenJava', MavenPublication) {
+            from components.java
+        }
+    }
+    repositories {
+        maven {
+            url "file://${project.projectDir}/repo"
+        }
+    }
+}
+
+tasks.withType(JavaCompile).configureEach {
+    options.encoding = 'UTF-8' // Use the UTF-8 charset for Java compilation
+}
+
+// IDEA no longer automatically downloads sources/javadoc jars for dependencies, so we need to explicitly enable the behavior.
+idea {
+    module {
+        downloadSources = true
+        downloadJavadoc = true
+    }
+}
--- a/gradle.properties
+++ b/gradle.properties
@@ -0,0 +1,39 @@
+# Sets default memory used for gradle commands. Can be overridden by user or command line properties.
+org.gradle.jvmargs=-Xmx1G
+org.gradle.daemon=true
+org.gradle.parallel=true
+org.gradle.caching=true
+org.gradle.configuration-cache=true
+
+#read more on this at https://github.com/neoforged/ModDevGradle?tab=readme-ov-file#better-minecraft-parameter-names--javadoc-parchment
+# you can also find the latest versions at: https://parchmentmc.org/docs/getting-started
+parchment_minecraft_version=1.21.1
+parchment_mappings_version=2024.11.17
+# Environment Properties
+# You can find the latest versions here: https://projects.neoforged.net/neoforged/neoforge
+# The Minecraft version must agree with the Neo version to get a valid artifact
+minecraft_version=1.21.1
+# The Minecraft version range can use any release version of Minecraft as bounds.
+# Snapshots, pre-releases, and release candidates are not guaranteed to sort properly
+# as they do not follow standard versioning conventions.
+minecraft_version_range=[1.21.1]
+# The Neo version must agree with the Minecraft version to get a valid artifact
+neo_version=21.1.220
+# The loader version range can only use the major version of FML as bounds
+loader_version_range=[1,)
+
+## Mod Properties
+
+# The unique mod identifier for the mod. Must be lowercase in English locale. Must fit the regex [a-z][a-z0-9_]{1,63}
+# Must match the String constant located in the main mod class annotated with @Mod.
+mod_id=trade
+# The human-readable display name for the mod.
+mod_name=Trading Screen
+# The license of the mod. Review your options at https://choosealicense.com/. All Rights Reserved is the default.
+mod_license=All Rights Reserved
+# The mod version. See https://semver.org/
+mod_version=1.0.0
+# The group ID for the mod. It is only important when publishing as an artifact to a Maven repository.
+# This should match the base package used for the mod sources.
+# See https://maven.apache.org/guides/mini/guide-naming-conventions.html
+mod_group_id=com.trunksbomb.trade
--- a/gradle/wrapper/gradle-wrapper.jar
+++ b/gradle/wrapper/gradle-wrapper.jar
--- a/gradle/wrapper/gradle-wrapper.properties
+++ b/gradle/wrapper/gradle-wrapper.properties
@@ -0,0 +1,7 @@
+distributionBase=GRADLE_USER_HOME
+distributionPath=wrapper/dists
+distributionUrl=https\://services.gradle.org/distributions/gradle-9.2.1-bin.zip
+networkTimeout=10000
+validateDistributionUrl=true
+zipStoreBase=GRADLE_USER_HOME
+zipStorePath=wrapper/dists
--- a/251
+++ b/251
@@ -0,0 +1,251 @@
+#!/bin/sh
+
+#
+# Copyright © 2015-2021 the original authors.
+#
+# Licensed under the Apache License, Version 2.0 (the "License");
+# you may not use this file except in compliance with the License.
+# You may obtain a copy of the License at
+#
+#      https://www.apache.org/licenses/LICENSE-2.0
+#
+# Unless required by applicable law or agreed to in writing, software
+# distributed under the License is distributed on an "AS IS" BASIS,
+# WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+# See the License for the specific language governing permissions and
+# limitations under the License.
+#
+# SPDX-License-Identifier: Apache-2.0
+#
+
+##############################################################################
+#
+#   Gradle start up script for POSIX generated by Gradle.
+#
+#   Important for running:
+#
+#   (1) You need a POSIX-compliant shell to run this script. If your /bin/sh is
+#       noncompliant, but you have some other compliant shell such as ksh or
+#       bash, then to run this script, type that shell name before the whole
+#       command line, like:
+#
+#           ksh Gradle
+#
+#       Busybox and similar reduced shells will NOT work, because this script
+#       requires all of these POSIX shell features:
+#         * functions;
+#         * expansions «$var», «${var}», «${var:-default}», «${var+SET}»,
+#           «${var#prefix}», «${var%suffix}», and «$( cmd )»;
+#         * compound commands having a testable exit status, especially «case»;
+#         * various built-in commands including «command», «set», and «ulimit».
+#
+#   Important for patching:
+#
+#   (2) This script targets any POSIX shell, so it avoids extensions provided
+#       by Bash, Ksh, etc; in particular arrays are avoided.
+#
+#       The "traditional" practice of packing multiple parameters into a
+#       space-separated string is a well documented source of bugs and security
+#       problems, so this is (mostly) avoided, by progressively accumulating
+#       options in "$@", and eventually passing that to Java.
+#
+#       Where the inherited environment variables (DEFAULT_JVM_OPTS, JAVA_OPTS,
+#       and GRADLE_OPTS) rely on word-splitting, this is performed explicitly;
+#       see the in-line comments for details.
+#
+#       There are tweaks for specific operating systems such as AIX, CygWin,
+#       Darwin, MinGW, and NonStop.
+#
+#   (3) This script is generated from the Groovy template
+#       https://github.com/gradle/gradle/blob/HEAD/platforms/jvm/plugins-application/src/main/resources/org/gradle/api/internal/plugins/unixStartScript.txt
+#       within the Gradle project.
+#
+#       You can find Gradle at https://github.com/gradle/gradle/.
+#
+##############################################################################
+
+# Attempt to set APP_HOME
+
+# Resolve links: $0 may be a link
+app_path=$0
+
+# Need this for daisy-chained symlinks.
+while
+    APP_HOME=${app_path%"${app_path##*/}"}  # leaves a trailing /; empty if no leading path
+    [ -h "$app_path" ]
+do
+    ls=$( ls -ld "$app_path" )
+    link=${ls#*' -> '}
+    case $link in             #(
+      /*)   app_path=$link ;; #(
+      *)    app_path=$APP_HOME$link ;;
+    esac
+done
+
+# This is normally unused
+# shellcheck disable=SC2034
+APP_BASE_NAME=${0##*/}
+# Discard cd standard output in case $CDPATH is set (https://github.com/gradle/gradle/issues/25036)
+APP_HOME=$( cd -P "${APP_HOME:-./}" > /dev/null && printf '%s\n' "$PWD" ) || exit
+
+# Use the maximum available, or set MAX_FD != -1 to use that value.
+MAX_FD=maximum
+
+warn () {
+    echo "$*"
+} >&2
+
+die () {
+    echo
+    echo "$*"
+    echo
+    exit 1
+} >&2
+
+# OS specific support (must be 'true' or 'false').
+cygwin=false
+msys=false
+darwin=false
+nonstop=false
+case "$( uname )" in                #(
+  CYGWIN* )         cygwin=true  ;; #(
+  Darwin* )         darwin=true  ;; #(
+  MSYS* | MINGW* )  msys=true    ;; #(
+  NONSTOP* )        nonstop=true ;;
+esac
+
+CLASSPATH="\\\"\\\""
+
+
+# Determine the Java command to use to start the JVM.
+if [ -n "$JAVA_HOME" ] ; then
+    if [ -x "$JAVA_HOME/jre/sh/java" ] ; then
+        # IBM's JDK on AIX uses strange locations for the executables
+        JAVACMD=$JAVA_HOME/jre/sh/java
+    else
+        JAVACMD=$JAVA_HOME/bin/java
+    fi
+    if [ ! -x "$JAVACMD" ] ; then
+        die "ERROR: JAVA_HOME is set to an invalid directory: $JAVA_HOME
+
+Please set the JAVA_HOME variable in your environment to match the
+location of your Java installation."
+    fi
+else
+    JAVACMD=java
+    if ! command -v java >/dev/null 2>&1
+    then
+        die "ERROR: JAVA_HOME is not set and no 'java' command could be found in your PATH.
+
+Please set the JAVA_HOME variable in your environment to match the
+location of your Java installation."
+    fi
+fi
+
+# Increase the maximum file descriptors if we can.
+if ! "$cygwin" && ! "$darwin" && ! "$nonstop" ; then
+    case $MAX_FD in #(
+      max*)
+        # In POSIX sh, ulimit -H is undefined. That's why the result is checked to see if it worked.
+        # shellcheck disable=SC2039,SC3045
+        MAX_FD=$( ulimit -H -n ) ||
+            warn "Could not query maximum file descriptor limit"
+    esac
+    case $MAX_FD in  #(
+      '' | soft) :;; #(
+      *)
+        # In POSIX sh, ulimit -n is undefined. That's why the result is checked to see if it worked.
+        # shellcheck disable=SC2039,SC3045
+        ulimit -n "$MAX_FD" ||
+            warn "Could not set maximum file descriptor limit to $MAX_FD"
+    esac
+fi
+
+# Collect all arguments for the java command, stacking in reverse order:
+#   * args from the command line
+#   * the main class name
+#   * -classpath
+#   * -D...appname settings
+#   * --module-path (only if needed)
+#   * DEFAULT_JVM_OPTS, JAVA_OPTS, and GRADLE_OPTS environment variables.
+
+# For Cygwin or MSYS, switch paths to Windows format before running java
+if "$cygwin" || "$msys" ; then
+    APP_HOME=$( cygpath --path --mixed "$APP_HOME" )
+    CLASSPATH=$( cygpath --path --mixed "$CLASSPATH" )
+
+    JAVACMD=$( cygpath --unix "$JAVACMD" )
+
+    # Now convert the arguments - kludge to limit ourselves to /bin/sh
+    for arg do
+        if
+            case $arg in                                #(
+              -*)   false ;;                            # don't mess with options #(
+              /?*)  t=${arg#/} t=/${t%%/*}              # looks like a POSIX filepath
+                    [ -e "$t" ] ;;                      #(
+              *)    false ;;
+            esac
+        then
+            arg=$( cygpath --path --ignore --mixed "$arg" )
+        fi
+        # Roll the args list around exactly as many times as the number of
+        # args, so each arg winds up back in the position where it started, but
+        # possibly modified.
+        #
+        # NB: a `for` loop captures its iteration list before it begins, so
+        # changing the positional parameters here affects neither the number of
+        # iterations, nor the values presented in `arg`.
+        shift                   # remove old arg
+        set -- "$@" "$arg"      # push replacement arg
+    done
+fi
+
+
+# Add default JVM options here. You can also use JAVA_OPTS and GRADLE_OPTS to pass JVM options to this script.
+DEFAULT_JVM_OPTS='"-Xmx64m" "-Xms64m"'
+
+# Collect all arguments for the java command:
+#   * DEFAULT_JVM_OPTS, JAVA_OPTS, and optsEnvironmentVar are not allowed to contain shell fragments,
+#     and any embedded shellness will be escaped.
+#   * For example: A user cannot expect ${Hostname} to be expanded, as it is an environment variable and will be
+#     treated as '${Hostname}' itself on the command line.
+
+set -- \
+        "-Dorg.gradle.appname=$APP_BASE_NAME" \
+        -classpath "$CLASSPATH" \
+        -jar "$APP_HOME/gradle/wrapper/gradle-wrapper.jar" \
+        "$@"
+
+# Stop when "xargs" is not available.
+if ! command -v xargs >/dev/null 2>&1
+then
+    die "xargs is not available"
+fi
+
+# Use "xargs" to parse quoted args.
+#
+# With -n1 it outputs one arg per line, with the quotes and backslashes removed.
+#
+# In Bash we could simply go:
+#
+#   readarray ARGS < <( xargs -n1 <<<"$var" ) &&
+#   set -- "${ARGS[@]}" "$@"
+#
+# but POSIX shell has neither arrays nor command substitution, so instead we
+# post-process each arg (as a line of input to sed) to backslash-escape any
+# character that might be a shell metacharacter, then use eval to reverse
+# that process (while maintaining the separation between arguments), and wrap
+# the whole thing up as a single "set" statement.
+#
+# This will of course break if any of these variables contains a newline or
+# an unmatched quote.
+#
+
+eval "set -- $(
+        printf '%s\n' "$DEFAULT_JVM_OPTS $JAVA_OPTS $GRADLE_OPTS" |
+        xargs -n1 |
+        sed ' s~[^-[:alnum:]+,./:=@_]~\\&~g; ' |
+        tr '\n' ' '
+    )" '"$@"'
+
+exec "$JAVACMD" "$@"
--- a/gradlew.bat
+++ b/gradlew.bat
@@ -0,0 +1,94 @@
+@rem
+@rem Copyright 2015 the original author or authors.
+@rem
+@rem Licensed under the Apache License, Version 2.0 (the "License");
+@rem you may not use this file except in compliance with the License.
+@rem You may obtain a copy of the License at
+@rem
+@rem      https://www.apache.org/licenses/LICENSE-2.0
+@rem
+@rem Unless required by applicable law or agreed to in writing, software
+@rem distributed under the License is distributed on an "AS IS" BASIS,
+@rem WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+@rem See the License for the specific language governing permissions and
+@rem limitations under the License.
+@rem
+@rem SPDX-License-Identifier: Apache-2.0
+@rem
+
+@if "%DEBUG%"=="" @echo off
+@rem ##########################################################################
+@rem
+@rem  Gradle startup script for Windows
+@rem
+@rem ##########################################################################
+
+@rem Set local scope for the variables with windows NT shell
+if "%OS%"=="Windows_NT" setlocal
+
+set DIRNAME=%~dp0
+if "%DIRNAME%"=="" set DIRNAME=.
+@rem This is normally unused
+set APP_BASE_NAME=%~n0
+set APP_HOME=%DIRNAME%
+
+@rem Resolve any "." and ".." in APP_HOME to make it shorter.
+for %%i in ("%APP_HOME%") do set APP_HOME=%%~fi
+
+@rem Add default JVM options here. You can also use JAVA_OPTS and GRADLE_OPTS to pass JVM options to this script.
+set DEFAULT_JVM_OPTS="-Xmx64m" "-Xms64m"
+
+@rem Find java.exe
+if defined JAVA_HOME goto findJavaFromJavaHome
+
+set JAVA_EXE=java.exe
+%JAVA_EXE% -version >NUL 2>&1
+if %ERRORLEVEL% equ 0 goto execute
+
+echo. 1>&2
+echo ERROR: JAVA_HOME is not set and no 'java' command could be found in your PATH. 1>&2
+echo. 1>&2
+echo Please set the JAVA_HOME variable in your environment to match the 1>&2
+echo location of your Java installation. 1>&2
+
+goto fail
+
+:findJavaFromJavaHome
+set JAVA_HOME=%JAVA_HOME:"=%
+set JAVA_EXE=%JAVA_HOME%/bin/java.exe
+
+if exist "%JAVA_EXE%" goto execute
+
+echo. 1>&2
+echo ERROR: JAVA_HOME is set to an invalid directory: %JAVA_HOME% 1>&2
+echo. 1>&2
+echo Please set the JAVA_HOME variable in your environment to match the 1>&2
+echo location of your Java installation. 1>&2
+
+goto fail
+
+:execute
+@rem Setup the command line
+
+set CLASSPATH=
+
+
+@rem Execute Gradle
+"%JAVA_EXE%" %DEFAULT_JVM_OPTS% %JAVA_OPTS% %GRADLE_OPTS% "-Dorg.gradle.appname=%APP_BASE_NAME%" -classpath "%CLASSPATH%" -jar "%APP_HOME%\gradle\wrapper\gradle-wrapper.jar" %*
+
+:end
+@rem End local scope for the variables with windows NT shell
+if %ERRORLEVEL% equ 0 goto mainEnd
+
+:fail
+rem Set variable GRADLE_EXIT_CONSOLE if you need the _script_ return code instead of
+rem the _cmd.exe /c_ return code!
+set EXIT_CODE=%ERRORLEVEL%
+if %EXIT_CODE% equ 0 set EXIT_CODE=1
+if not ""=="%GRADLE_EXIT_CONSOLE%" exit %EXIT_CODE%
+exit /b %EXIT_CODE%
+
+:mainEnd
+if "%OS%"=="Windows_NT" endlocal
+
+:omega
--- a/settings.gradle
+++ b/settings.gradle
@@ -0,0 +1,9 @@
+pluginManagement {
+    repositories {
+        gradlePluginPortal()
+    }
+}
+
+plugins {
+    id 'org.gradle.toolchains.foojay-resolver-convention' version '1.0.0'
+}
--- a/src/main/java/com/trunksbomb/trade/client/TradeClientState.java
+++ b/src/main/java/com/trunksbomb/trade/client/TradeClientState.java
@@ -0,0 +1,45 @@
+package com.trunksbomb.trade.mod.client;
+
+import com.trunksbomb.trade.mod.trade.TradeView;
+import java.util.UUID;
+import net.minecraft.client.Minecraft;
+import net.minecraft.network.chat.Component;
+
+public final class TradeClientState {
+    private static Minecraft minecraft;
+
+    private TradeClientState() {}
+
+    public static void init(Minecraft minecraftInstance) {
+        minecraft = minecraftInstance;
+    }
+
+    public static Minecraft minecraft() {
+        return minecraft;
+    }
+
+    public static void showOrUpdate(Minecraft minecraftInstance, TradeView view) {
+        minecraft = minecraftInstance;
+        if (minecraft.screen instanceof TradeScreen screen && screen.sessionId().equals(view.sessionId())) {
+            screen.updateView(view);
+            return;
+        }
+
+        if (minecraft.player == null) {
+            return;
+        }
+
+        minecraft.setScreen(new TradeScreen(new TradeScreen.TradeMenu(0, minecraft.player.getInventory(), view), minecraft.player.getInventory(), Component.literal("Trade")));
+    }
+
+    public static void closeTrade(Minecraft minecraftInstance, UUID sessionId, Component reason) {
+        minecraft = minecraftInstance;
+        if (minecraft.screen instanceof TradeScreen screen && screen.sessionId().equals(sessionId)) {
+            minecraft.setScreen(null);
+        }
+
+        if (minecraft.player != null) {
+            minecraft.player.displayClientMessage(reason, false);
+        }
+    }
+}
--- a/src/main/java/com/trunksbomb/trade/client/TradeScreen.java
+++ b/src/main/java/com/trunksbomb/trade/client/TradeScreen.java
@@ -0,0 +1,311 @@
+package com.trunksbomb.trade.mod.client;
+
+import com.trunksbomb.trade.mod.network.TradeActionPayload;
+import com.trunksbomb.trade.mod.network.DebugTradeControlPayload;
+import com.trunksbomb.trade.mod.trade.DebugControlAction;
+import com.trunksbomb.trade.mod.trade.TradeAction;
+import com.trunksbomb.trade.mod.trade.TradeStage;
+import com.trunksbomb.trade.mod.trade.TradeView;
+import java.util.UUID;
+import net.minecraft.client.gui.GuiGraphics;
+import net.minecraft.client.gui.components.Button;
+import net.minecraft.client.gui.screens.inventory.AbstractContainerScreen;
+import net.minecraft.network.chat.Component;
+import net.minecraft.resources.ResourceLocation;
+import net.minecraft.world.Container;
+import net.minecraft.world.SimpleContainer;
+import net.minecraft.world.entity.player.Inventory;
+import net.minecraft.world.entity.player.Player;
+import net.minecraft.world.inventory.AbstractContainerMenu;
+import net.minecraft.world.inventory.ClickType;
+import net.minecraft.world.inventory.MenuType;
+import net.minecraft.world.inventory.Slot;
+import net.minecraft.world.item.ItemStack;
+import net.neoforged.neoforge.network.PacketDistributor;
+
+public class TradeScreen extends AbstractContainerScreen<TradeScreen.TradeMenu> {
+    private static final ResourceLocation TEXTURE = ResourceLocation.fromNamespaceAndPath("trade", "textures/gui/trade.png");
+    private static final int LEFT_OFFER_START_X = 8;
+    private static final int RIGHT_OFFER_START_X = 170;
+    private static final int OFFER_START_Y = 18;
+    private static final int INVENTORY_START_X = 62;
+    private static final int INVENTORY_START_Y = 139;
+    private static final int CENTER_COLUMN_X = 115;
+    private static final int STATUS_LABEL_Y = 54;
+    private static final int ACCEPT_BUTTON_Y = 74;
+    private static final int CANCEL_BUTTON_Y = 98;
+    private static final int ACTION_BUTTON_WIDTH = 48;
+    private static final int ACTION_BUTTON_HEIGHT = 20;
+    private static final int DEBUG_PANEL_OFFSET_X = 96;
+    private static final int DEBUG_BUTTON_WIDTH = 86;
+    private static final int DEBUG_BUTTON_HEIGHT = 20;
+    private static final int DEBUG_BUTTON_GAP = 4;
+    private static final int CONFIRM_PANEL_X = 89;
+    private static final int CONFIRM_PANEL_Y = 77;
+    private static final int CONFIRM_PANEL_WIDTH = 106;
+    private static final int CONFIRM_PANEL_HEIGHT = 64;
+
+    public TradeScreen(TradeMenu menu, Inventory inventory, Component title) {
+        super(menu, inventory, title);
+        this.imageWidth = 284;
+        this.imageHeight = 221;
+        this.inventoryLabelX = INVENTORY_START_X;
+        this.inventoryLabelY = INVENTORY_START_Y - 11;
+    }
+
+    public UUID sessionId() {
+        return menu.view().sessionId();
+    }
+
+    public void updateView(TradeView view) {
+        menu.updateView(view);
+    }
+
+    @Override
+    protected void init() {
+        super.init();
+        titleLabelX = LEFT_OFFER_START_X;
+        titleLabelY = 6;
+
+        addRenderableWidget(Button.builder(Component.literal("Accept"), button -> sendAction(TradeAction.ACCEPT, -1, false))
+                .bounds(leftPos + CENTER_COLUMN_X + 3, topPos + ACCEPT_BUTTON_Y, ACTION_BUTTON_WIDTH, ACTION_BUTTON_HEIGHT)
+                .build());
+        addRenderableWidget(Button.builder(Component.literal("Cancel"), button -> sendAction(TradeAction.DECLINE, -1, false))
+                .bounds(leftPos + CENTER_COLUMN_X + 3, topPos + CANCEL_BUTTON_Y, ACTION_BUTTON_WIDTH, ACTION_BUTTON_HEIGHT)
+                .build());
+
+        if (menu.view().debugMode()) {
+            int debugX = leftPos - DEBUG_PANEL_OFFSET_X;
+            int debugY = topPos + 8;
+            addRenderableWidget(Button.builder(Component.literal("Debug Accept"), button -> sendDebug(DebugControlAction.ACCEPT))
+                    .bounds(debugX, debugY, DEBUG_BUTTON_WIDTH, DEBUG_BUTTON_HEIGHT)
+                    .build());
+            addRenderableWidget(Button.builder(Component.literal("Debug Cancel"), button -> sendDebug(DebugControlAction.CANCEL))
+                    .bounds(debugX, debugY + (DEBUG_BUTTON_HEIGHT + DEBUG_BUTTON_GAP), DEBUG_BUTTON_WIDTH, DEBUG_BUTTON_HEIGHT)
+                    .build());
+            addRenderableWidget(Button.builder(Component.literal("Add Random"), button -> sendDebug(DebugControlAction.APPEND_RANDOM))
+                    .bounds(debugX, debugY + 2 * (DEBUG_BUTTON_HEIGHT + DEBUG_BUTTON_GAP), DEBUG_BUTTON_WIDTH, DEBUG_BUTTON_HEIGHT)
+                    .build());
+            addRenderableWidget(Button.builder(Component.literal("Remove Item"), button -> sendDebug(DebugControlAction.REMOVE_LAST))
+                    .bounds(debugX, debugY + 3 * (DEBUG_BUTTON_HEIGHT + DEBUG_BUTTON_GAP), DEBUG_BUTTON_WIDTH, DEBUG_BUTTON_HEIGHT)
+                    .build());
+        }
+    }
+
+    @Override
+    public boolean keyPressed(int keyCode, int scanCode, int modifiers) {
+        if (minecraft != null && minecraft.options.keyInventory.matches(keyCode, scanCode)) {
+            onClose();
+            return true;
+        }
+        return super.keyPressed(keyCode, scanCode, modifiers);
+    }
+
+    @Override
+    public void onClose() {
+        sendAction(TradeAction.CLOSE, -1, false);
+        if (minecraft != null) {
+            minecraft.setScreen(null);
+        }
+    }
+
+    @Override
+    public boolean mouseClicked(double mouseX, double mouseY, int button) {
+        if (menu.view().stage() == TradeStage.CONFIRMING) {
+            return super.mouseClicked(mouseX, mouseY, button);
+        }
+
+        if (hoveredSlot instanceof SelfOfferSlot selfOfferSlot) {
+            sendAction(TradeAction.REMOVE_ITEM, selfOfferSlot.offerIndex(), button == 1);
+            return true;
+        }
+
+        if (hoveredSlot instanceof OtherOfferSlot) {
+            return true;
+        }
+
+        if (hoveredSlot != null && hoveredSlot.container == menu.playerInventory()) {
+            sendAction(TradeAction.ADD_ITEM, hoveredSlot.getSlotIndex(), button == 1);
+            return true;
+        }
+
+        return super.mouseClicked(mouseX, mouseY, button);
+    }
+
+    @Override
+    protected void renderBg(GuiGraphics guiGraphics, float partialTick, int mouseX, int mouseY) {
+        guiGraphics.blit(TEXTURE, leftPos, topPos, 0, 0, imageWidth, imageHeight, imageWidth, imageHeight);
+        if (menu.view().stage() == TradeStage.CONFIRMING) {
+            renderConfirmationOverlay(guiGraphics);
+        }
+    }
+
+    @Override
+    protected void renderLabels(GuiGraphics guiGraphics, int mouseX, int mouseY) {
+        guiGraphics.drawString(font, menu.view().selfName(), titleLabelX, titleLabelY, 0x404040, false);
+        guiGraphics.drawString(font, menu.view().otherName(), RIGHT_OFFER_START_X, 6, 0x404040, false);
+        guiGraphics.drawString(font, playerInventoryTitle, inventoryLabelX, inventoryLabelY, 0x404040, false);
+        if (menu.view().otherAccepted()) {
+            drawScaledCenteredColumnText(guiGraphics, "Other player", STATUS_LABEL_Y, 0x2E7D32, 0.7F);
+            drawScaledCenteredColumnText(guiGraphics, "has accepted", STATUS_LABEL_Y + 7, 0x2E7D32, 0.7F);
+        }
+        if (menu.view().stage() == TradeStage.CONFIRMING) {
+            drawCenteredColumnText(guiGraphics, "FINAL", 16, 0x7A4F00);
+            drawCenteredColumnText(guiGraphics, "CONFIRM", 28, 0x7A4F00);
+        }
+    }
+
+    @Override
+    public void render(GuiGraphics guiGraphics, int mouseX, int mouseY, float partialTick) {
+        super.render(guiGraphics, mouseX, mouseY, partialTick);
+        renderTooltip(guiGraphics, mouseX, mouseY);
+    }
+
+    private void sendAction(TradeAction action, int slot, boolean secondary) {
+        if (minecraft == null || minecraft.getConnection() == null) {
+            return;
+        }
+        PacketDistributor.sendToServer(new TradeActionPayload(menu.view().sessionId(), action, slot, secondary));
+    }
+
+    private void sendDebug(DebugControlAction action) {
+        if (minecraft == null || minecraft.getConnection() == null) {
+            return;
+        }
+        PacketDistributor.sendToServer(new DebugTradeControlPayload(menu.view().sessionId(), action, ""));
+    }
+
+    private void renderConfirmationOverlay(GuiGraphics guiGraphics) {
+        int panelLeft = leftPos + CONFIRM_PANEL_X;
+        int panelTop = topPos + CONFIRM_PANEL_Y;
+        guiGraphics.fill(leftPos, topPos, leftPos + imageWidth, topPos + imageHeight, 0x22000000);
+        guiGraphics.fill(panelLeft, panelTop, panelLeft + CONFIRM_PANEL_WIDTH, panelTop + CONFIRM_PANEL_HEIGHT, 0xDDF7D48C);
+        guiGraphics.fill(panelLeft + 1, panelTop + 1, panelLeft + CONFIRM_PANEL_WIDTH - 1, panelTop + CONFIRM_PANEL_HEIGHT - 1, 0xAAFFF4D6);
+        guiGraphics.drawString(font, Component.literal("Confirm Trade"), panelLeft + 11, panelTop + 9, 0x5B3A00, false);
+        guiGraphics.drawString(font, Component.literal("Review items"), panelLeft + 18, panelTop + 24, 0x5B3A00, false);
+        guiGraphics.drawString(font, Component.literal("No more changes"), panelLeft + 9, panelTop + 36, 0x5B3A00, false);
+    }
+
+    private void drawCenteredColumnText(GuiGraphics guiGraphics, String text, int y, int color) {
+        int textX = CENTER_COLUMN_X + (ACTION_BUTTON_WIDTH / 2) - (font.width(text) / 2);
+        guiGraphics.drawString(font, text, textX, y, color, false);
+    }
+
+    private void drawScaledCenteredColumnText(GuiGraphics guiGraphics, String text, int y, int color, float scale) {
+        var pose = guiGraphics.pose();
+        pose.pushPose();
+        pose.scale(scale, scale, 1.0F);
+        float scaledCenterX = CENTER_COLUMN_X + 3 + (ACTION_BUTTON_WIDTH / 2.0F);
+        float drawX = (scaledCenterX - (font.width(text) * scale / 2.0F)) / scale;
+        float drawY = y / scale;
+        guiGraphics.drawString(font, text, (int) drawX, (int) drawY, color, false);
+        pose.popPose();
+    }
+
+    public static class TradeMenu extends AbstractContainerMenu {
+        private static final int OFFER_COLUMNS = 6;
+        private static final int OFFER_ROWS = 6;
+        private TradeView view;
+        private final Inventory playerInventory;
+        private final SimpleContainer selfOffer = new SimpleContainer(TradeView.OFFER_SLOT_COUNT);
+        private final SimpleContainer otherOffer = new SimpleContainer(TradeView.OFFER_SLOT_COUNT);
+
+        public TradeMenu(int containerId, Inventory inventory, TradeView view) {
+            super(MenuType.GENERIC_9x6, containerId);
+            this.playerInventory = inventory;
+            this.view = view;
+            syncOfferContainers();
+
+            for (int row = 0; row < OFFER_ROWS; row++) {
+                for (int col = 0; col < OFFER_COLUMNS; col++) {
+                    int slot = col + row * OFFER_COLUMNS;
+                    addSlot(new SelfOfferSlot(selfOffer, slot, LEFT_OFFER_START_X + col * 18, OFFER_START_Y + row * 18));
+                }
+            }
+
+            for (int row = 0; row < OFFER_ROWS; row++) {
+                for (int col = 0; col < OFFER_COLUMNS; col++) {
+                    int slot = col + row * OFFER_COLUMNS;
+                    addSlot(new OtherOfferSlot(otherOffer, slot, RIGHT_OFFER_START_X + col * 18, OFFER_START_Y + row * 18));
+                }
+            }
+
+            for (int row = 0; row < 3; row++) {
+                for (int col = 0; col < 9; col++) {
+                    int slot = col + row * 9 + 9;
+                    addSlot(new Slot(inventory, slot, INVENTORY_START_X + col * 18, INVENTORY_START_Y + row * 18));
+                }
+            }
+
+            for (int col = 0; col < 9; col++) {
+                addSlot(new Slot(inventory, col, INVENTORY_START_X + col * 18, INVENTORY_START_Y + 58));
+            }
+        }
+
+        public TradeView view() {
+            return view;
+        }
+
+        public Inventory playerInventory() {
+            return playerInventory;
+        }
+
+        public void updateView(TradeView view) {
+            this.view = view;
+            syncOfferContainers();
+        }
+
+        private void syncOfferContainers() {
+            for (int i = 0; i < TradeView.OFFER_SLOT_COUNT; i++) {
+                selfOffer.setItem(i, view.selfOffer().get(i).copy());
+                otherOffer.setItem(i, view.otherOffer().get(i).copy());
+            }
+        }
+
+        @Override
+        public void clicked(int slotId, int button, ClickType clickType, Player player) {
+            // All interaction is routed through custom trade packets instead of vanilla container clicks.
+        }
+
+        @Override
+        public ItemStack quickMoveStack(Player player, int index) {
+            return ItemStack.EMPTY;
+        }
+
+        @Override
+        public boolean stillValid(Player player) {
+            return true;
+        }
+    }
+
+    private static class SelfOfferSlot extends Slot {
+        public SelfOfferSlot(Container container, int slot, int x, int y) {
+            super(container, slot, x, y);
+        }
+
+        public int offerIndex() {
+            return getSlotIndex();
+        }
+
+        @Override
+        public boolean mayPlace(ItemStack stack) {
+            return false;
+        }
+    }
+
+    private static class OtherOfferSlot extends Slot {
+        public OtherOfferSlot(Container container, int slot, int x, int y) {
+            super(container, slot, x, y);
+        }
+
+        @Override
+        public boolean mayPickup(Player player) {
+            return false;
+        }
+
+        @Override
+        public boolean mayPlace(ItemStack stack) {
+            return false;
+        }
+    }
+}
--- a/src/main/java/com/trunksbomb/trade/command/TradeCommand.java
+++ b/src/main/java/com/trunksbomb/trade/command/TradeCommand.java
@@ -0,0 +1,160 @@
+package com.trunksbomb.trade.mod.command;
+
+import com.mojang.brigadier.CommandDispatcher;
+import com.mojang.brigadier.arguments.StringArgumentType;
+import com.mojang.brigadier.suggestion.SuggestionsBuilder;
+import com.trunksbomb.trade.mod.trade.DebugTradeSession;
+import com.trunksbomb.trade.mod.trade.TradeManager;
+import java.util.concurrent.CompletableFuture;
+import net.minecraft.commands.CommandSourceStack;
+import net.minecraft.commands.Commands;
+import net.minecraft.network.chat.Component;
+import net.minecraft.server.level.ServerPlayer;
+
+public final class TradeCommand {
+    private TradeCommand() {}
+
+    public static void register(CommandDispatcher<CommandSourceStack> dispatcher) {
+        dispatcher.register(Commands.literal("trade")
+                .then(Commands.literal("debug")
+                        .then(Commands.literal("init").executes(context -> initDebug(context.getSource())))
+                        .then(Commands.literal("offer")
+                                .then(Commands.argument("spec", StringArgumentType.greedyString())
+                                        .executes(context -> setDebugOffer(
+                                                context.getSource(),
+                                                StringArgumentType.getString(context, "spec")))))
+                        .then(Commands.literal("remove")
+                                .then(Commands.argument("spec", StringArgumentType.greedyString())
+                                        .executes(context -> removeDebugOffer(
+                                                context.getSource(),
+                                                StringArgumentType.getString(context, "spec")))))
+                        .then(Commands.literal("accept").executes(context -> acceptDebug(context.getSource())))
+                        .then(Commands.literal("cancel").executes(context -> cancelDebug(context.getSource())))
+                        .then(Commands.literal("close").executes(context -> closeDebug(context.getSource()))))
+                .then(Commands.argument("player", StringArgumentType.word())
+                        .suggests((context, builder) -> suggestPlayers(context.getSource(), builder))
+                        .executes(context -> startTrade(context.getSource(), StringArgumentType.getString(context, "player")))));
+    }
+
+    private static CompletableFuture<com.mojang.brigadier.suggestion.Suggestions> suggestPlayers(CommandSourceStack source, SuggestionsBuilder builder) {
+        for (ServerPlayer player : source.getServer().getPlayerList().getPlayers()) {
+            if (!player.getGameProfile().getName().equalsIgnoreCase(source.getTextName())) {
+                builder.suggest(player.getGameProfile().getName());
+            }
+        }
+        return builder.buildFuture();
+    }
+
+    private static int startTrade(CommandSourceStack source, String targetName) {
+        if (!(source.getEntity() instanceof ServerPlayer player)) {
+            source.sendFailure(Component.literal("Only players can start trades."));
+            return 0;
+        }
+
+        ServerPlayer target = source.getServer().getPlayerList().getPlayerByName(targetName);
+        if (target == null) {
+            source.sendFailure(Component.literal("That player is not online."));
+            return 0;
+        }
+
+        if (target == player) {
+            source.sendFailure(Component.literal("You cannot trade with yourself."));
+            return 0;
+        }
+
+        if (!TradeManager.get(source.getServer()).startTrade(player, target)) {
+            source.sendFailure(Component.literal("Trade could not be started. One of you is already trading."));
+            return 0;
+        }
+
+        source.sendSuccess(() -> Component.literal("Trade opened with " + target.getGameProfile().getName() + "."), false);
+        return 1;
+    }
+
+    private static int initDebug(CommandSourceStack source) {
+        if (!(source.getEntity() instanceof ServerPlayer player)) {
+            source.sendFailure(Component.literal("Only players can start debug trades."));
+            return 0;
+        }
+
+        if (!TradeManager.get(source.getServer()).initDebugTrade(player)) {
+            source.sendFailure(Component.literal("You are already in a trade."));
+            return 0;
+        }
+
+        source.sendSuccess(() -> Component.literal("Debug trade initialized."), false);
+        return 1;
+    }
+
+    private static int setDebugOffer(CommandSourceStack source, String spec) {
+        if (!(source.getEntity() instanceof ServerPlayer player)) {
+            source.sendFailure(Component.literal("Only players can control debug trades."));
+            return 0;
+        }
+
+        try {
+            if (!TradeManager.get(source.getServer()).setDebugOffer(player, DebugTradeSession.parseOfferSpec(spec))) {
+                source.sendFailure(Component.literal("Start a debug trade first with /trade debug init."));
+                return 0;
+            }
+        } catch (IllegalArgumentException exception) {
+            source.sendFailure(Component.literal(exception.getMessage()));
+            return 0;
+        }
+
+        source.sendSuccess(() -> Component.literal("Debug offer updated."), false);
+        return 1;
+    }
+
+    private static int acceptDebug(CommandSourceStack source) {
+        return runDebugAction(source, TradeManager.get(source.getServer())::acceptDebug, "Debug trader accepted.");
+    }
+
+    private static int removeDebugOffer(CommandSourceStack source, String spec) {
+        if (!(source.getEntity() instanceof ServerPlayer player)) {
+            source.sendFailure(Component.literal("Only players can control debug trades."));
+            return 0;
+        }
+
+        try {
+            int result = TradeManager.get(source.getServer()).removeDebugOffer(player, spec);
+            if (result < 0) {
+                source.sendFailure(Component.literal("Start a debug trade first with /trade debug init."));
+                return 0;
+            }
+            if (result == 0) {
+                source.sendFailure(Component.literal("That debug offer slot is already empty."));
+                return 0;
+            }
+        } catch (IllegalArgumentException exception) {
+            source.sendFailure(Component.literal(exception.getMessage()));
+            return 0;
+        }
+
+        source.sendSuccess(() -> Component.literal("Debug offer updated."), false);
+        return 1;
+    }
+
+    private static int cancelDebug(CommandSourceStack source) {
+        return runDebugAction(source, TradeManager.get(source.getServer())::cancelDebug, "Debug trader cancelled.");
+    }
+
+    private static int closeDebug(CommandSourceStack source) {
+        return runDebugAction(source, TradeManager.get(source.getServer())::closeDebug, "Debug trade closed.");
+    }
+
+    private static int runDebugAction(CommandSourceStack source, java.util.function.Predicate<ServerPlayer> action, String successMessage) {
+        if (!(source.getEntity() instanceof ServerPlayer player)) {
+            source.sendFailure(Component.literal("Only players can control debug trades."));
+            return 0;
+        }
+
+        if (!action.test(player)) {
+            source.sendFailure(Component.literal("Start a debug trade first with /trade debug init."));
+            return 0;
+        }
+
+        source.sendSuccess(() -> Component.literal(successMessage), false);
+        return 1;
+    }
+}
--- a/src/main/java/com/trunksbomb/trade/mod/TradeClientMod.java
+++ b/src/main/java/com/trunksbomb/trade/mod/TradeClientMod.java
@@ -0,0 +1,18 @@
+package com.trunksbomb.trade.mod;
+
+import com.trunksbomb.trade.mod.client.TradeClientState;
+import net.minecraft.client.Minecraft;
+import net.neoforged.api.distmarker.Dist;
+import net.neoforged.bus.api.SubscribeEvent;
+import net.neoforged.fml.common.EventBusSubscriber;
+import net.neoforged.fml.common.Mod;
+import net.neoforged.fml.event.lifecycle.FMLClientSetupEvent;
+
+@Mod(value = TradeMod.MODID, dist = Dist.CLIENT)
+@EventBusSubscriber(modid = TradeMod.MODID, value = Dist.CLIENT)
+public class TradeClientMod {
+    @SubscribeEvent
+    static void onClientSetup(FMLClientSetupEvent event) {
+        event.enqueueWork(() -> TradeClientState.init(Minecraft.getInstance()));
+    }
+}
--- a/src/main/java/com/trunksbomb/trade/mod/TradeMod.java
+++ b/src/main/java/com/trunksbomb/trade/mod/TradeMod.java
@@ -0,0 +1,46 @@
+package com.trunksbomb.trade.mod;
+
+import com.mojang.logging.LogUtils;
+import com.trunksbomb.trade.mod.command.TradeCommand;
+import com.trunksbomb.trade.mod.network.TradeNetworking;
+import com.trunksbomb.trade.mod.trade.TradeManager;
+import net.neoforged.bus.api.IEventBus;
+import net.neoforged.fml.common.Mod;
+import net.neoforged.fml.event.lifecycle.FMLCommonSetupEvent;
+import net.neoforged.neoforge.common.NeoForge;
+import net.neoforged.neoforge.event.RegisterCommandsEvent;
+import net.neoforged.neoforge.event.entity.player.PlayerEvent;
+import net.neoforged.neoforge.network.event.RegisterPayloadHandlersEvent;
+import org.slf4j.Logger;
+
+@Mod(TradeMod.MODID)
+public class TradeMod {
+    public static final String MODID = "trade";
+    public static final Logger LOGGER = LogUtils.getLogger();
+
+    public TradeMod(IEventBus modEventBus) {
+        modEventBus.addListener(this::commonSetup);
+        modEventBus.addListener(this::registerPayloads);
+        NeoForge.EVENT_BUS.addListener(this::registerCommands);
+        NeoForge.EVENT_BUS.addListener(this::onPlayerLogout);
+    }
+
+    private void commonSetup(FMLCommonSetupEvent event) {
+        LOGGER.info("Initializing trading screen");
+    }
+
+    private void registerPayloads(RegisterPayloadHandlersEvent event) {
+        TradeNetworking.register(event.registrar("1"));
+    }
+
+    public void registerCommands(RegisterCommandsEvent event) {
+        LOGGER.info("Registering /trade command");
+        TradeCommand.register(event.getDispatcher());
+    }
+
+    public void onPlayerLogout(PlayerEvent.PlayerLoggedOutEvent event) {
+        if (event.getEntity() instanceof net.minecraft.server.level.ServerPlayer player) {
+            TradeManager.get(player.server).handleDisconnect(player);
+        }
+    }
+}
--- a/src/main/java/com/trunksbomb/trade/network/DebugTradeControlPayload.java
+++ b/src/main/java/com/trunksbomb/trade/network/DebugTradeControlPayload.java
@@ -0,0 +1,31 @@
+package com.trunksbomb.trade.mod.network;
+
+import com.trunksbomb.trade.mod.TradeMod;
+import com.trunksbomb.trade.mod.trade.DebugControlAction;
+import java.util.UUID;
+import net.minecraft.network.RegistryFriendlyByteBuf;
+import net.minecraft.network.codec.StreamCodec;
+import net.minecraft.network.protocol.common.custom.CustomPacketPayload;
+import net.minecraft.resources.ResourceLocation;
+
+public record DebugTradeControlPayload(UUID sessionId, DebugControlAction action, String spec) implements CustomPacketPayload {
+    public static final Type<DebugTradeControlPayload> TYPE = new Type<>(ResourceLocation.fromNamespaceAndPath(TradeMod.MODID, "debug_trade_control"));
+    public static final StreamCodec<RegistryFriendlyByteBuf, DebugTradeControlPayload> STREAM_CODEC = new StreamCodec<>() {
+        @Override
+        public void encode(RegistryFriendlyByteBuf buf, DebugTradeControlPayload value) {
+            buf.writeUUID(value.sessionId());
+            buf.writeEnum(value.action());
+            buf.writeUtf(value.spec(), 256);
+        }
+
+        @Override
+        public DebugTradeControlPayload decode(RegistryFriendlyByteBuf buf) {
+            return new DebugTradeControlPayload(buf.readUUID(), buf.readEnum(DebugControlAction.class), buf.readUtf(256));
+        }
+    };
+
+    @Override
+    public Type<? extends CustomPacketPayload> type() {
+        return TYPE;
+    }
+}
--- a/src/main/java/com/trunksbomb/trade/network/TradeActionPayload.java
+++ b/src/main/java/com/trunksbomb/trade/network/TradeActionPayload.java
@@ -0,0 +1,32 @@
+package com.trunksbomb.trade.mod.network;
+
+import com.trunksbomb.trade.mod.TradeMod;
+import com.trunksbomb.trade.mod.trade.TradeAction;
+import java.util.UUID;
+import net.minecraft.network.RegistryFriendlyByteBuf;
+import net.minecraft.network.codec.StreamCodec;
+import net.minecraft.network.protocol.common.custom.CustomPacketPayload;
+import net.minecraft.resources.ResourceLocation;
+
+public record TradeActionPayload(UUID sessionId, TradeAction action, int slot, boolean secondary) implements CustomPacketPayload {
+    public static final Type<TradeActionPayload> TYPE = new Type<>(ResourceLocation.fromNamespaceAndPath(TradeMod.MODID, "trade_action"));
+    public static final StreamCodec<RegistryFriendlyByteBuf, TradeActionPayload> STREAM_CODEC = new StreamCodec<>() {
+        @Override
+        public void encode(RegistryFriendlyByteBuf buf, TradeActionPayload value) {
+            buf.writeUUID(value.sessionId);
+            buf.writeEnum(value.action);
+            buf.writeVarInt(value.slot);
+            buf.writeBoolean(value.secondary);
+        }
+
+        @Override
+        public TradeActionPayload decode(RegistryFriendlyByteBuf buf) {
+            return new TradeActionPayload(buf.readUUID(), buf.readEnum(TradeAction.class), buf.readVarInt(), buf.readBoolean());
+        }
+    };
+
+    @Override
+    public Type<? extends CustomPacketPayload> type() {
+        return TYPE;
+    }
+}
--- a/src/main/java/com/trunksbomb/trade/network/TradeClosePayload.java
+++ b/src/main/java/com/trunksbomb/trade/network/TradeClosePayload.java
@@ -0,0 +1,31 @@
+package com.trunksbomb.trade.mod.network;
+
+import com.trunksbomb.trade.mod.TradeMod;
+import java.util.UUID;
+import net.minecraft.network.RegistryFriendlyByteBuf;
+import net.minecraft.network.chat.Component;
+import net.minecraft.network.chat.ComponentSerialization;
+import net.minecraft.network.codec.StreamCodec;
+import net.minecraft.network.protocol.common.custom.CustomPacketPayload;
+import net.minecraft.resources.ResourceLocation;
+
+public record TradeClosePayload(UUID sessionId, Component reason) implements CustomPacketPayload {
+    public static final Type<TradeClosePayload> TYPE = new Type<>(ResourceLocation.fromNamespaceAndPath(TradeMod.MODID, "trade_close"));
+    public static final StreamCodec<RegistryFriendlyByteBuf, TradeClosePayload> STREAM_CODEC = new StreamCodec<>() {
+        @Override
+        public void encode(RegistryFriendlyByteBuf buf, TradeClosePayload value) {
+            buf.writeUUID(value.sessionId);
+            ComponentSerialization.STREAM_CODEC.encode(buf, value.reason);
+        }
+
+        @Override
+        public TradeClosePayload decode(RegistryFriendlyByteBuf buf) {
+            return new TradeClosePayload(buf.readUUID(), ComponentSerialization.STREAM_CODEC.decode(buf));
+        }
+    };
+
+    @Override
+    public Type<? extends CustomPacketPayload> type() {
+        return TYPE;
+    }
+}
--- a/src/main/java/com/trunksbomb/trade/network/TradeNetworking.java
+++ b/src/main/java/com/trunksbomb/trade/network/TradeNetworking.java
@@ -0,0 +1,77 @@
+package com.trunksbomb.trade.mod.network;
+
+import com.trunksbomb.trade.mod.client.TradeScreen;
+import com.trunksbomb.trade.mod.trade.TradeManager;
+import net.minecraft.client.Minecraft;
+import net.minecraft.network.chat.Component;
+import net.minecraft.server.level.ServerPlayer;
+import net.neoforged.neoforge.network.handling.DirectionalPayloadHandler;
+import net.neoforged.neoforge.network.handling.IPayloadContext;
+import net.neoforged.neoforge.network.registration.PayloadRegistrar;
+
+public final class TradeNetworking {
+    private TradeNetworking() {}
+
+    public static void register(PayloadRegistrar registrar) {
+        registrar.playBidirectional(
+                TradeStatePayload.TYPE,
+                TradeStatePayload.STREAM_CODEC,
+                new DirectionalPayloadHandler<>(TradeNetworking::handleTradeStateClient, TradeNetworking::ignoreTradeStateServer));
+        registrar.playBidirectional(
+                TradeClosePayload.TYPE,
+                TradeClosePayload.STREAM_CODEC,
+                new DirectionalPayloadHandler<>(TradeNetworking::handleTradeCloseClient, TradeNetworking::ignoreTradeCloseServer));
+        registrar.playToServer(
+                TradeActionPayload.TYPE,
+                TradeActionPayload.STREAM_CODEC,
+                TradeNetworking::handleTradeActionServer);
+        registrar.playToServer(
+                DebugTradeControlPayload.TYPE,
+                DebugTradeControlPayload.STREAM_CODEC,
+                TradeNetworking::handleDebugTradeControlServer);
+    }
+
+    private static void handleTradeStateClient(TradeStatePayload payload, IPayloadContext context) {
+        Minecraft minecraft = Minecraft.getInstance();
+        if (minecraft.player == null) {
+            return;
+        }
+
+        if (minecraft.screen instanceof TradeScreen screen && screen.sessionId().equals(payload.view().sessionId())) {
+            screen.updateView(payload.view());
+            return;
+        }
+
+        minecraft.setScreen(new TradeScreen(
+                new TradeScreen.TradeMenu(0, minecraft.player.getInventory(), payload.view()),
+                minecraft.player.getInventory(),
+                Component.literal("Trade")));
+    }
+
+    private static void handleTradeCloseClient(TradeClosePayload payload, IPayloadContext context) {
+        Minecraft minecraft = Minecraft.getInstance();
+        if (minecraft.screen instanceof TradeScreen screen && screen.sessionId().equals(payload.sessionId())) {
+            minecraft.setScreen(null);
+        }
+
+        if (minecraft.player != null) {
+            minecraft.player.displayClientMessage(payload.reason(), false);
+        }
+    }
+
+    private static void handleTradeActionServer(TradeActionPayload payload, IPayloadContext context) {
+        if (context.player() instanceof ServerPlayer player) {
+            TradeManager.get(player.server).handleAction(player, payload.sessionId(), payload.action(), payload.slot(), payload.secondary());
+        }
+    }
+
+    private static void handleDebugTradeControlServer(DebugTradeControlPayload payload, IPayloadContext context) {
+        if (context.player() instanceof ServerPlayer player) {
+            TradeManager.get(player.server).handleDebugControl(player, payload.sessionId(), payload.action(), payload.spec());
+        }
+    }
+
+    private static void ignoreTradeStateServer(TradeStatePayload payload, IPayloadContext context) {}
+
+    private static void ignoreTradeCloseServer(TradeClosePayload payload, IPayloadContext context) {}
+}
--- a/src/main/java/com/trunksbomb/trade/network/TradeStatePayload.java
+++ b/src/main/java/com/trunksbomb/trade/network/TradeStatePayload.java
@@ -0,0 +1,28 @@
+package com.trunksbomb.trade.mod.network;
+
+import com.trunksbomb.trade.mod.TradeMod;
+import com.trunksbomb.trade.mod.trade.TradeView;
+import net.minecraft.network.RegistryFriendlyByteBuf;
+import net.minecraft.network.codec.StreamCodec;
+import net.minecraft.network.protocol.common.custom.CustomPacketPayload;
+import net.minecraft.resources.ResourceLocation;
+
+public record TradeStatePayload(TradeView view) implements CustomPacketPayload {
+    public static final Type<TradeStatePayload> TYPE = new Type<>(ResourceLocation.fromNamespaceAndPath(TradeMod.MODID, "trade_state"));
+    public static final StreamCodec<RegistryFriendlyByteBuf, TradeStatePayload> STREAM_CODEC = new StreamCodec<>() {
+        @Override
+        public void encode(RegistryFriendlyByteBuf buf, TradeStatePayload value) {
+            TradeView.STREAM_CODEC.encode(buf, value.view);
+        }
+
+        @Override
+        public TradeStatePayload decode(RegistryFriendlyByteBuf buf) {
+            return new TradeStatePayload(TradeView.STREAM_CODEC.decode(buf));
+        }
+    };
+
+    @Override
+    public Type<? extends CustomPacketPayload> type() {
+        return TYPE;
+    }
+}
--- a/src/main/java/com/trunksbomb/trade/trade/DebugControlAction.java
+++ b/src/main/java/com/trunksbomb/trade/trade/DebugControlAction.java
@@ -0,0 +1,11 @@
+package com.trunksbomb.trade.mod.trade;
+
+public enum DebugControlAction {
+    SET_OFFER,
+    APPEND_RANDOM,
+    REMOVE_OFFER,
+    REMOVE_LAST,
+    ACCEPT,
+    CANCEL,
+    CLOSE
+}
--- a/src/main/java/com/trunksbomb/trade/trade/DebugTradeSession.java
+++ b/src/main/java/com/trunksbomb/trade/trade/DebugTradeSession.java
@@ -0,0 +1,405 @@
+package com.trunksbomb.trade.mod.trade;
+
+import com.trunksbomb.trade.mod.network.TradeClosePayload;
+import com.trunksbomb.trade.mod.network.TradeStatePayload;
+import java.util.ArrayList;
+import java.util.List;
+import java.util.UUID;
+import net.minecraft.core.registries.BuiltInRegistries;
+import net.minecraft.network.chat.Component;
+import net.minecraft.resources.ResourceLocation;
+import net.minecraft.server.level.ServerPlayer;
+import net.minecraft.world.entity.player.Inventory;
+import net.minecraft.world.item.Item;
+import net.minecraft.world.item.ItemStack;
+import net.neoforged.neoforge.network.PacketDistributor;
+
+public class DebugTradeSession {
+    private static final int INVENTORY_SLOT_COUNT = TradeView.INVENTORY_SLOT_COUNT;
+    private static final int OFFER_SLOT_COUNT = TradeView.OFFER_SLOT_COUNT;
+    private static final String DEBUG_NAME = "Debug Trader";
+    private static final net.minecraft.util.RandomSource RANDOM = net.minecraft.util.RandomSource.create();
+
+    private final UUID id = UUID.randomUUID();
+    private final ServerPlayer player;
+    private final List<ItemStack> selfOffer = blankOffer();
+    private final List<ItemStack> otherOffer = blankStacks();
+    private boolean selfAccepted;
+    private boolean otherAccepted;
+    private TradeStage stage = TradeStage.OFFERING;
+
+    public DebugTradeSession(ServerPlayer player) {
+        this.player = player;
+    }
+
+    public UUID id() {
+        return id;
+    }
+
+    public ServerPlayer player() {
+        return player;
+    }
+
+    public void sync() {
+        PacketDistributor.sendToPlayer(player, new TradeStatePayload(view()));
+    }
+
+    public void close(Component reason) {
+        PacketDistributor.sendToPlayer(player, new TradeClosePayload(id, reason));
+    }
+
+    public boolean addFromInventory(int inventorySlot, boolean singleItem) {
+        if (stage != TradeStage.OFFERING || inventorySlot < 0 || inventorySlot >= INVENTORY_SLOT_COUNT) {
+            return false;
+        }
+
+        Inventory inventory = player.getInventory();
+        ItemStack sourceStack = inventory.getItem(inventorySlot);
+        if (sourceStack.isEmpty()) {
+            return false;
+        }
+
+        ItemStack moving = sourceStack.copyWithCount(singleItem ? 1 : sourceStack.getCount());
+        if (!insertStack(selfOffer, moving)) {
+            return false;
+        }
+
+        sourceStack.shrink(singleItem ? 1 : sourceStack.getCount());
+        if (sourceStack.isEmpty()) {
+            inventory.setItem(inventorySlot, ItemStack.EMPTY);
+        }
+        inventory.setChanged();
+        clearAccepts();
+        return true;
+    }
+
+    public boolean removeFromOffer(int offerSlot, boolean singleItem) {
+        if (stage != TradeStage.OFFERING || offerSlot < 0 || offerSlot >= OFFER_SLOT_COUNT) {
+            return false;
+        }
+
+        ItemStack offered = selfOffer.get(offerSlot);
+        if (offered.isEmpty()) {
+            return false;
+        }
+
+        List<ItemStack> workingInventory = inventorySnapshot();
+        ItemStack returned = offered.copyWithCount(singleItem ? 1 : offered.getCount());
+        if (!insertStack(workingInventory, returned)) {
+            return false;
+        }
+
+        Inventory inventory = player.getInventory();
+        for (int i = 0; i < workingInventory.size(); i++) {
+            inventory.setItem(i, workingInventory.get(i));
+        }
+        inventory.setChanged();
+
+        if (singleItem && offered.getCount() > 1) {
+            ItemStack updated = offered.copy();
+            updated.shrink(1);
+            selfOffer.set(offerSlot, updated);
+        } else {
+            selfOffer.set(offerSlot, ItemStack.EMPTY);
+        }
+
+        clearAccepts();
+        return true;
+    }
+
+    public void acceptSelf() {
+        selfAccepted = true;
+    }
+
+    public void acceptOther() {
+        otherAccepted = true;
+    }
+
+    public void setOtherOffer(List<ItemStack> offer) {
+        for (int i = 0; i < OFFER_SLOT_COUNT; i++) {
+            otherOffer.set(i, i < offer.size() ? offer.get(i).copy() : ItemStack.EMPTY);
+        }
+        clearAccepts();
+    }
+
+    public boolean appendOtherOffer(List<ItemStack> offer) {
+        boolean changed = false;
+        for (ItemStack stack : offer) {
+            if (stack.isEmpty()) {
+                continue;
+            }
+            if (!insertStack(otherOffer, stack.copy())) {
+                break;
+            }
+            changed = true;
+        }
+
+        if (changed) {
+            clearAccepts();
+        }
+        return changed;
+    }
+
+    public boolean removeOtherOffer(String spec) {
+        if ("all".equalsIgnoreCase(spec)) {
+            for (int i = 0; i < OFFER_SLOT_COUNT; i++) {
+                otherOffer.set(i, ItemStack.EMPTY);
+            }
+            clearAccepts();
+            return true;
+        }
+
+        int split = spec.indexOf(':');
+        if (split <= 0 || split >= spec.length() - 1) {
+            throw new IllegalArgumentException("Use all or slot:count");
+        }
+
+        int slot = parsePositiveInt(spec.substring(0, split), "slot") - 1;
+        int count = parsePositiveInt(spec.substring(split + 1), "count");
+        if (slot < 0 || slot >= OFFER_SLOT_COUNT) {
+            throw new IllegalArgumentException("Slot must be between 1 and " + OFFER_SLOT_COUNT + ".");
+        }
+
+        ItemStack stack = otherOffer.get(slot);
+        if (stack.isEmpty()) {
+            return false;
+        }
+
+        if (count >= stack.getCount()) {
+            otherOffer.set(slot, ItemStack.EMPTY);
+        } else {
+            ItemStack updated = stack.copy();
+            updated.shrink(count);
+            otherOffer.set(slot, updated);
+        }
+
+        clearAccepts();
+        return true;
+    }
+
+    public boolean removeLastOtherOffer() {
+        for (int i = OFFER_SLOT_COUNT - 1; i >= 0; i--) {
+            if (otherOffer.get(i).isEmpty()) {
+                continue;
+            }
+            otherOffer.set(i, ItemStack.EMPTY);
+            clearAccepts();
+            return true;
+        }
+        return false;
+    }
+
+    public void advanceToConfirmation() {
+        if (stage == TradeStage.OFFERING && selfAccepted && otherAccepted) {
+            stage = TradeStage.CONFIRMING;
+            selfAccepted = false;
+            otherAccepted = false;
+        }
+    }
+
+    public boolean bothAccepted() {
+        return selfAccepted && otherAccepted;
+    }
+
+    public boolean isConfirmationStage() {
+        return stage == TradeStage.CONFIRMING;
+    }
+
+    public boolean completeTrade() {
+        List<ItemStack> result = inventorySnapshot();
+        for (ItemStack stack : otherOffer) {
+            if (!stack.isEmpty() && !insertStack(result, stack.copy())) {
+                return false;
+            }
+        }
+
+        Inventory inventory = player.getInventory();
+        for (int i = 0; i < result.size(); i++) {
+            inventory.setItem(i, result.get(i));
+        }
+        inventory.setChanged();
+        return true;
+    }
+
+    public TradeView view() {
+        return new TradeView(
+                id,
+                player.getGameProfile().getName(),
+                DEBUG_NAME,
+                true,
+                stage,
+                selfAccepted,
+                otherAccepted,
+                inventorySnapshot(),
+                emptyReservedSnapshot(),
+                selfOfferSnapshot(),
+                otherOfferSnapshot());
+    }
+
+    public static List<ItemStack> parseOfferSpec(String spec) {
+        if (spec.startsWith("random:")) {
+            return parseRandomOffer(spec);
+        }
+
+        int split = spec.lastIndexOf(':');
+        if (split <= 0 || split >= spec.length() - 1) {
+            throw new IllegalArgumentException("Use item:count or random:count or random:numStacks:stackCount");
+        }
+
+        ResourceLocation itemId = ResourceLocation.tryParse(spec.substring(0, split));
+        if (itemId == null) {
+            throw new IllegalArgumentException("Invalid item id.");
+        }
+
+        Item item = BuiltInRegistries.ITEM.get(itemId);
+        if (item == null || item == net.minecraft.world.item.Items.AIR) {
+            throw new IllegalArgumentException("Unknown item: " + itemId);
+        }
+
+        int count = parsePositiveInt(spec.substring(split + 1), "count");
+        return List.of(new ItemStack(item, count));
+    }
+
+    private static List<ItemStack> parseRandomOffer(String spec) {
+        String[] parts = spec.split(":");
+        List<Item> items = BuiltInRegistries.ITEM.stream()
+                .filter(item -> item != net.minecraft.world.item.Items.AIR)
+                .toList();
+
+        if (parts.length == 2) {
+            int count = parsePositiveInt(parts[1], "count");
+            return List.of(new ItemStack(randomItem(items), count));
+        }
+
+        if (parts.length == 3) {
+            int numStacks = parsePositiveInt(parts[1], "numStacks");
+            int stackCount = parsePositiveInt(parts[2], "stackCount");
+            List<ItemStack> result = new ArrayList<>();
+            for (int i = 0; i < Math.min(numStacks, OFFER_SLOT_COUNT); i++) {
+                result.add(new ItemStack(randomItem(items), stackCount));
+            }
+            return result;
+        }
+
+        throw new IllegalArgumentException("Use random:count or random:numStacks:stackCount");
+    }
+
+    private static Item randomItem(List<Item> items) {
+        return items.get(RANDOM.nextInt(items.size()));
+    }
+
+    public static List<ItemStack> randomSingleStackOffer() {
+        List<Item> items = BuiltInRegistries.ITEM.stream()
+                .filter(item -> item != net.minecraft.world.item.Items.AIR)
+                .toList();
+        Item item = randomItem(items);
+        int maxCount = Math.max(1, Math.min(item.getDefaultMaxStackSize(), 64));
+        int count = 1 + RANDOM.nextInt(maxCount);
+        return List.of(new ItemStack(item, count));
+    }
+
+    private static int parsePositiveInt(String value, String label) {
+        try {
+            int parsed = Integer.parseInt(value);
+            if (parsed <= 0) {
+                throw new IllegalArgumentException(label + " must be positive.");
+            }
+            return parsed;
+        } catch (NumberFormatException exception) {
+            throw new IllegalArgumentException("Invalid " + label + ": " + value);
+        }
+    }
+
+    private static boolean insertStack(List<ItemStack> working, ItemStack incoming) {
+        if (incoming.isEmpty()) {
+            return true;
+        }
+
+        for (int i = 0; i < working.size(); i++) {
+            ItemStack existing = working.get(i);
+            if (existing.isEmpty() || !ItemStack.isSameItemSameComponents(existing, incoming)) {
+                continue;
+            }
+
+            int space = existing.getMaxStackSize() - existing.getCount();
+            if (space <= 0) {
+                continue;
+            }
+
+            int moved = Math.min(space, incoming.getCount());
+            ItemStack updated = existing.copy();
+            updated.grow(moved);
+            working.set(i, updated);
+            incoming.shrink(moved);
+            if (incoming.isEmpty()) {
+                return true;
+            }
+        }
+
+        for (int i = 0; i < working.size(); i++) {
+            if (!working.get(i).isEmpty()) {
+                continue;
+            }
+            working.set(i, incoming.copy());
+            incoming.setCount(0);
+            return true;
+        }
+
+        return false;
+    }
+
+    private static List<Integer> emptyReservedSnapshot() {
+        List<Integer> result = new ArrayList<>(INVENTORY_SLOT_COUNT);
+        for (int i = 0; i < INVENTORY_SLOT_COUNT; i++) {
+            result.add(0);
+        }
+        return result;
+    }
+
+    private void clearAccepts() {
+        selfAccepted = false;
+        otherAccepted = false;
+    }
+
+    private List<ItemStack> inventorySnapshot() {
+        List<ItemStack> result = new ArrayList<>(INVENTORY_SLOT_COUNT);
+        Inventory inventory = player.getInventory();
+        for (int i = 0; i < INVENTORY_SLOT_COUNT; i++) {
+            result.add(inventory.getItem(i).copy());
+        }
+        return result;
+    }
+
+    private List<ItemStack> selfOfferSnapshot() {
+        List<ItemStack> result = new ArrayList<>(OFFER_SLOT_COUNT);
+        for (ItemStack stack : selfOffer) {
+            result.add(stack.copy());
+        }
+        return result;
+    }
+
+    private List<ItemStack> otherOfferSnapshot() {
+        List<ItemStack> result = new ArrayList<>(OFFER_SLOT_COUNT);
+        for (ItemStack stack : otherOffer) {
+            result.add(stack.copy());
+        }
+        return result;
+    }
+
+    private static List<ItemStack> blankOffer() {
+        List<ItemStack> result = new ArrayList<>(OFFER_SLOT_COUNT);
+        for (int i = 0; i < OFFER_SLOT_COUNT; i++) {
+            result.add(ItemStack.EMPTY);
+        }
+        return result;
+    }
+
+    private static List<ItemStack> blankStacks() {
+        List<ItemStack> result = new ArrayList<>(OFFER_SLOT_COUNT);
+        for (int i = 0; i < OFFER_SLOT_COUNT; i++) {
+            result.add(ItemStack.EMPTY);
+        }
+        return result;
+    }
+
+}
--- a/src/main/java/com/trunksbomb/trade/trade/TradeAction.java
+++ b/src/main/java/com/trunksbomb/trade/trade/TradeAction.java
@@ -0,0 +1,9 @@
+package com.trunksbomb.trade.mod.trade;
+
+public enum TradeAction {
+    ADD_ITEM,
+    REMOVE_ITEM,
+    ACCEPT,
+    DECLINE,
+    CLOSE
+}
--- a/src/main/java/com/trunksbomb/trade/trade/TradeEntry.java
+++ b/src/main/java/com/trunksbomb/trade/trade/TradeEntry.java
@@ -0,0 +1,5 @@
+package com.trunksbomb.trade.mod.trade;
+
+import net.minecraft.world.item.ItemStack;
+
+public record TradeEntry(int sourceSlot, ItemStack stack) {}
--- a/src/main/java/com/trunksbomb/trade/trade/TradeManager.java
+++ b/src/main/java/com/trunksbomb/trade/trade/TradeManager.java
@@ -0,0 +1,309 @@
+package com.trunksbomb.trade.mod.trade;
+
+import java.util.HashMap;
+import java.util.List;
+import java.util.Map;
+import java.util.UUID;
+import java.util.WeakHashMap;
+import net.minecraft.network.chat.Component;
+import net.minecraft.server.MinecraftServer;
+import net.minecraft.server.level.ServerPlayer;
+import net.minecraft.world.item.ItemStack;
+
+public class TradeManager {
+    private static final Map<MinecraftServer, TradeManager> INSTANCES = new WeakHashMap<>();
+
+    private final Map<UUID, TradeSession> sessionsById = new HashMap<>();
+    private final Map<UUID, UUID> sessionByPlayer = new HashMap<>();
+    private final Map<UUID, DebugTradeSession> debugSessionsById = new HashMap<>();
+    private final Map<UUID, UUID> debugSessionByPlayer = new HashMap<>();
+
+    public static TradeManager get(MinecraftServer server) {
+        return INSTANCES.computeIfAbsent(server, ignored -> new TradeManager());
+    }
+
+    public boolean startTrade(ServerPlayer first, ServerPlayer second) {
+        if (isTrading(first) || isTrading(second)) {
+            return false;
+        }
+
+        TradeSession session = new TradeSession(first, second);
+        sessionsById.put(session.id(), session);
+        sessionByPlayer.put(first.getUUID(), session.id());
+        sessionByPlayer.put(second.getUUID(), session.id());
+        session.syncToPlayers();
+        first.sendSystemMessage(Component.literal("Trade opened with " + second.getGameProfile().getName() + "."));
+        second.sendSystemMessage(Component.literal("Trade opened with " + first.getGameProfile().getName() + "."));
+        return true;
+    }
+
+    public void handleAction(ServerPlayer player, UUID sessionId, TradeAction action, int slot, boolean secondary) {
+        TradeSession session = sessionsById.get(sessionId);
+        if (session != null && session.involves(player)) {
+            handleRealAction(player, session, action, slot, secondary);
+            return;
+        }
+
+        DebugTradeSession debugSession = debugSessionsById.get(sessionId);
+        if (debugSession != null && debugSession.player() == player) {
+            handleDebugAction(debugSession, action, slot, secondary);
+            return;
+        }
+    }
+
+    private void handleRealAction(ServerPlayer player, TradeSession session, TradeAction action, int slot, boolean secondary) {
+        boolean changed = switch (action) {
+            case ADD_ITEM -> session.addFromInventory(player, slot, secondary);
+            case REMOVE_ITEM -> session.removeFromOffer(player, slot, secondary);
+            case ACCEPT -> {
+                session.accept(player);
+                yield true;
+            }
+            case DECLINE, CLOSE -> {
+                cancel(session, Component.literal(player.getGameProfile().getName() + " cancelled the trade."));
+                yield false;
+            }
+        };
+
+        if (!changed) {
+            return;
+        }
+
+        if (!session.isConfirmationStage()) {
+            session.advanceToConfirmation();
+            session.syncToPlayers();
+            return;
+        }
+
+        if (!session.bothAccepted()) {
+            session.syncToPlayers();
+            return;
+        }
+
+        if (session.completeTrade()) {
+            finish(session, Component.literal("Trade completed."));
+        } else {
+            cancel(session, Component.literal("Trade cancelled because one player could not fit all traded items."));
+        }
+    }
+
+    private void handleDebugAction(DebugTradeSession session, TradeAction action, int slot, boolean secondary) {
+        boolean changed = switch (action) {
+            case ADD_ITEM -> session.addFromInventory(slot, secondary);
+            case REMOVE_ITEM -> session.removeFromOffer(slot, secondary);
+            case ACCEPT -> {
+                session.acceptSelf();
+                yield true;
+            }
+            case DECLINE, CLOSE -> {
+                closeDebug(session, Component.literal("You closed the debug trade."));
+                yield false;
+            }
+        };
+
+        if (!changed) {
+            return;
+        }
+
+        if (!session.isConfirmationStage()) {
+            session.advanceToConfirmation();
+            session.sync();
+            return;
+        }
+
+        if (!session.bothAccepted()) {
+            session.sync();
+            return;
+        }
+
+        if (session.completeTrade()) {
+            finishDebug(session, Component.literal("Debug trade completed."));
+        } else {
+            closeDebug(session, Component.literal("Debug trade cancelled because the items would not fit."));
+        }
+    }
+
+    public void handleDisconnect(ServerPlayer player) {
+        TradeSession session = getSession(player);
+        if (session != null) {
+            cancel(session, Component.literal(player.getGameProfile().getName() + " left the game."));
+            return;
+        }
+
+        DebugTradeSession debugSession = getDebugSession(player);
+        if (debugSession != null) {
+            closeDebug(debugSession, Component.literal("Debug trade closed because you left the game."));
+        }
+    }
+
+    public boolean isTrading(ServerPlayer player) {
+        return sessionByPlayer.containsKey(player.getUUID()) || debugSessionByPlayer.containsKey(player.getUUID());
+    }
+
+    public boolean initDebugTrade(ServerPlayer player) {
+        if (isTrading(player)) {
+            return false;
+        }
+
+        DebugTradeSession session = new DebugTradeSession(player);
+        debugSessionsById.put(session.id(), session);
+        debugSessionByPlayer.put(player.getUUID(), session.id());
+        session.sync();
+        player.sendSystemMessage(Component.literal("Debug trade opened."));
+        return true;
+    }
+
+    public boolean setDebugOffer(ServerPlayer player, List<ItemStack> offer) {
+        DebugTradeSession session = getDebugSession(player);
+        if (session == null) {
+            return false;
+        }
+
+        session.setOtherOffer(offer);
+        session.sync();
+        return true;
+    }
+
+    public int removeDebugOffer(ServerPlayer player, String spec) {
+        DebugTradeSession session = getDebugSession(player);
+        if (session == null) {
+            return -1;
+        }
+
+        boolean changed = session.removeOtherOffer(spec);
+        if (changed) {
+            session.sync();
+            return 1;
+        }
+
+        return 0;
+    }
+
+    public boolean acceptDebug(ServerPlayer player) {
+        DebugTradeSession session = getDebugSession(player);
+        if (session == null) {
+            return false;
+        }
+
+        session.acceptOther();
+        if (!session.isConfirmationStage()) {
+            session.advanceToConfirmation();
+            session.sync();
+            return true;
+        }
+
+        if (session.bothAccepted()) {
+            if (session.completeTrade()) {
+                finishDebug(session, Component.literal("Debug trade completed."));
+            } else {
+                closeDebug(session, Component.literal("Debug trade cancelled because the items would not fit."));
+            }
+        } else {
+            session.sync();
+        }
+        return true;
+    }
+
+    public boolean cancelDebug(ServerPlayer player) {
+        DebugTradeSession session = getDebugSession(player);
+        if (session == null) {
+            return false;
+        }
+
+        closeDebug(session, Component.literal("Debug trader cancelled the trade."));
+        return true;
+    }
+
+    public boolean closeDebug(ServerPlayer player) {
+        DebugTradeSession session = getDebugSession(player);
+        if (session == null) {
+            return false;
+        }
+
+        closeDebug(session, Component.literal("Debug trade closed."));
+        return true;
+    }
+
+    public void handleDebugControl(ServerPlayer player, UUID sessionId, DebugControlAction action, String spec) {
+        DebugTradeSession session = debugSessionsById.get(sessionId);
+        if (session == null || session.player() != player) {
+            return;
+        }
+
+        try {
+            switch (action) {
+                case SET_OFFER -> {
+                    session.setOtherOffer(DebugTradeSession.parseOfferSpec(spec));
+                    session.sync();
+                }
+                case APPEND_RANDOM -> {
+                    if (session.appendOtherOffer(DebugTradeSession.randomSingleStackOffer())) {
+                        session.sync();
+                    }
+                }
+                case REMOVE_OFFER -> {
+                    if (session.removeOtherOffer(spec)) {
+                        session.sync();
+                    }
+                }
+                case REMOVE_LAST -> {
+                    if (session.removeLastOtherOffer()) {
+                        session.sync();
+                    }
+                }
+                case ACCEPT -> acceptDebug(player);
+                case CANCEL -> cancelDebug(player);
+                case CLOSE -> closeDebug(player);
+            }
+        } catch (IllegalArgumentException ignored) {
+            player.sendSystemMessage(Component.literal(ignored.getMessage()));
+        }
+    }
+
+    private TradeSession getSession(ServerPlayer player) {
+        UUID sessionId = sessionByPlayer.get(player.getUUID());
+        return sessionId == null ? null : sessionsById.get(sessionId);
+    }
+
+    private DebugTradeSession getDebugSession(ServerPlayer player) {
+        UUID sessionId = debugSessionByPlayer.get(player.getUUID());
+        return sessionId == null ? null : debugSessionsById.get(sessionId);
+    }
+
+    private void finish(TradeSession session, Component reason) {
+        session.firstPlayer().sendSystemMessage(reason);
+        session.secondPlayer().sendSystemMessage(reason);
+        session.close(reason);
+        removeSession(session);
+    }
+
+    private void cancel(TradeSession session, Component reason) {
+        session.firstPlayer().sendSystemMessage(reason);
+        session.secondPlayer().sendSystemMessage(reason);
+        session.close(reason);
+        removeSession(session);
+    }
+
+    private void removeSession(TradeSession session) {
+        sessionsById.remove(session.id());
+        sessionByPlayer.remove(session.firstPlayer().getUUID());
+        sessionByPlayer.remove(session.secondPlayer().getUUID());
+    }
+
+    private void finishDebug(DebugTradeSession session, Component reason) {
+        session.player().sendSystemMessage(reason);
+        session.close(reason);
+        removeDebugSession(session);
+    }
+
+    private void closeDebug(DebugTradeSession session, Component reason) {
+        session.player().sendSystemMessage(reason);
+        session.close(reason);
+        removeDebugSession(session);
+    }
+
+    private void removeDebugSession(DebugTradeSession session) {
+        debugSessionsById.remove(session.id());
+        debugSessionByPlayer.remove(session.player().getUUID());
+    }
+}
--- a/src/main/java/com/trunksbomb/trade/trade/TradeSession.java
+++ b/src/main/java/com/trunksbomb/trade/trade/TradeSession.java
@@ -0,0 +1,281 @@
+package com.trunksbomb.trade.mod.trade;
+
+import com.trunksbomb.trade.mod.network.TradeClosePayload;
+import com.trunksbomb.trade.mod.network.TradeStatePayload;
+import java.util.ArrayList;
+import java.util.List;
+import java.util.UUID;
+import net.minecraft.network.chat.Component;
+import net.minecraft.server.level.ServerPlayer;
+import net.minecraft.world.entity.player.Inventory;
+import net.minecraft.world.item.ItemStack;
+import net.neoforged.neoforge.network.PacketDistributor;
+
+public class TradeSession {
+    private static final int INVENTORY_SLOT_COUNT = TradeView.INVENTORY_SLOT_COUNT;
+    private static final int OFFER_SLOT_COUNT = TradeView.OFFER_SLOT_COUNT;
+
+    private final UUID id = UUID.randomUUID();
+    private final ServerPlayer first;
+    private final ServerPlayer second;
+    private final List<ItemStack> firstOffer = blankOffer();
+    private final List<ItemStack> secondOffer = blankOffer();
+    private boolean firstAccepted;
+    private boolean secondAccepted;
+    private TradeStage stage = TradeStage.OFFERING;
+
+    public TradeSession(ServerPlayer first, ServerPlayer second) {
+        this.first = first;
+        this.second = second;
+    }
+
+    public UUID id() {
+        return id;
+    }
+
+    public ServerPlayer firstPlayer() {
+        return first;
+    }
+
+    public ServerPlayer secondPlayer() {
+        return second;
+    }
+
+    public boolean involves(ServerPlayer player) {
+        return player == first || player == second;
+    }
+
+    public ServerPlayer other(ServerPlayer player) {
+        return player == first ? second : first;
+    }
+
+    public void syncToPlayers() {
+        sendState(first);
+        sendState(second);
+    }
+
+    public void close(Component reason) {
+        PacketDistributor.sendToPlayer(first, new TradeClosePayload(id, reason));
+        PacketDistributor.sendToPlayer(second, new TradeClosePayload(id, reason));
+    }
+
+    public boolean addFromInventory(ServerPlayer player, int inventorySlot, boolean singleItem) {
+        if (stage != TradeStage.OFFERING || inventorySlot < 0 || inventorySlot >= INVENTORY_SLOT_COUNT) {
+            return false;
+        }
+
+        List<ItemStack> offer = offerFor(player);
+        Inventory inventory = player.getInventory();
+        ItemStack sourceStack = inventory.getItem(inventorySlot);
+        if (sourceStack.isEmpty()) {
+            return false;
+        }
+
+        ItemStack moving = sourceStack.copyWithCount(singleItem ? 1 : sourceStack.getCount());
+        if (!insertStack(offer, moving)) {
+            return false;
+        }
+
+        sourceStack.shrink(singleItem ? 1 : sourceStack.getCount());
+        if (sourceStack.isEmpty()) {
+            inventory.setItem(inventorySlot, ItemStack.EMPTY);
+        }
+        inventory.setChanged();
+        clearAccepts();
+        return true;
+    }
+
+    public boolean removeFromOffer(ServerPlayer player, int offerSlot, boolean singleItem) {
+        if (stage != TradeStage.OFFERING || offerSlot < 0 || offerSlot >= OFFER_SLOT_COUNT) {
+            return false;
+        }
+
+        List<ItemStack> offer = offerFor(player);
+        ItemStack offered = offer.get(offerSlot);
+        if (offered.isEmpty()) {
+            return false;
+        }
+
+        Inventory inventory = player.getInventory();
+        List<ItemStack> workingInventory = inventorySnapshot(player);
+        ItemStack returned = offered.copyWithCount(singleItem ? 1 : offered.getCount());
+        if (!insertStack(workingInventory, returned)) {
+            return false;
+        }
+
+        applyInventory(player, workingInventory);
+        if (singleItem && offered.getCount() > 1) {
+            ItemStack updated = offered.copy();
+            updated.shrink(1);
+            offer.set(offerSlot, updated);
+        } else {
+            offer.set(offerSlot, ItemStack.EMPTY);
+        }
+        clearAccepts();
+        return true;
+    }
+
+    public void accept(ServerPlayer player) {
+        if (player == first) {
+            firstAccepted = true;
+        } else {
+            secondAccepted = true;
+        }
+    }
+
+    public void advanceToConfirmation() {
+        if (stage == TradeStage.OFFERING && firstAccepted && secondAccepted) {
+            stage = TradeStage.CONFIRMING;
+            firstAccepted = false;
+            secondAccepted = false;
+        }
+    }
+
+    public boolean bothAccepted() {
+        return firstAccepted && secondAccepted;
+    }
+
+    public boolean isConfirmationStage() {
+        return stage == TradeStage.CONFIRMING;
+    }
+
+    public boolean completeTrade() {
+        List<ItemStack> firstResult = simulateResult(first, secondOffer);
+        List<ItemStack> secondResult = simulateResult(second, firstOffer);
+        if (firstResult == null || secondResult == null) {
+            return false;
+        }
+
+        applyInventory(first, firstResult);
+        applyInventory(second, secondResult);
+        clearOffer(firstOffer);
+        clearOffer(secondOffer);
+        return true;
+    }
+
+    public TradeView viewFor(ServerPlayer player) {
+        boolean isFirst = player == first;
+        ServerPlayer other = isFirst ? second : first;
+        return new TradeView(
+                id,
+                player.getGameProfile().getName(),
+                other.getGameProfile().getName(),
+                false,
+                stage,
+                isFirst ? firstAccepted : secondAccepted,
+                isFirst ? secondAccepted : firstAccepted,
+                inventorySnapshot(player),
+                emptyReservedSnapshot(),
+                offerSnapshot(isFirst ? firstOffer : secondOffer),
+                offerSnapshot(isFirst ? secondOffer : firstOffer));
+    }
+
+    public void sendState(ServerPlayer player) {
+        PacketDistributor.sendToPlayer(player, new TradeStatePayload(viewFor(player)));
+    }
+
+    private List<ItemStack> simulateResult(ServerPlayer player, List<ItemStack> incoming) {
+        List<ItemStack> working = inventorySnapshot(player);
+        for (ItemStack stack : incoming) {
+            if (!stack.isEmpty() && !insertStack(working, stack.copy())) {
+                return null;
+            }
+        }
+
+        return working;
+    }
+
+    private static boolean insertStack(List<ItemStack> working, ItemStack incoming) {
+        if (incoming.isEmpty()) {
+            return true;
+        }
+
+        for (int i = 0; i < working.size(); i++) {
+            ItemStack existing = working.get(i);
+            if (existing.isEmpty() || !ItemStack.isSameItemSameComponents(existing, incoming)) {
+                continue;
+            }
+
+            int space = existing.getMaxStackSize() - existing.getCount();
+            if (space <= 0) {
+                continue;
+            }
+
+            int moved = Math.min(space, incoming.getCount());
+            ItemStack updated = existing.copy();
+            updated.grow(moved);
+            working.set(i, updated);
+            incoming.shrink(moved);
+            if (incoming.isEmpty()) {
+                return true;
+            }
+        }
+
+        for (int i = 0; i < working.size(); i++) {
+            if (!working.get(i).isEmpty()) {
+                continue;
+            }
+            working.set(i, incoming.copy());
+            incoming.setCount(0);
+            return true;
+        }
+
+        return false;
+    }
+
+    private static void clearOffer(List<ItemStack> offer) {
+        for (int i = 0; i < offer.size(); i++) {
+            offer.set(i, ItemStack.EMPTY);
+        }
+    }
+
+    private static void applyInventory(ServerPlayer player, List<ItemStack> result) {
+        Inventory inventory = player.getInventory();
+        for (int i = 0; i < result.size(); i++) {
+            inventory.setItem(i, result.get(i));
+        }
+        inventory.setChanged();
+    }
+
+    private static List<ItemStack> blankOffer() {
+        List<ItemStack> result = new ArrayList<>(OFFER_SLOT_COUNT);
+        for (int i = 0; i < OFFER_SLOT_COUNT; i++) {
+            result.add(ItemStack.EMPTY);
+        }
+        return result;
+    }
+
+    private void clearAccepts() {
+        firstAccepted = false;
+        secondAccepted = false;
+    }
+
+    private static List<Integer> emptyReservedSnapshot() {
+        List<Integer> result = new ArrayList<>(INVENTORY_SLOT_COUNT);
+        for (int i = 0; i < INVENTORY_SLOT_COUNT; i++) {
+            result.add(0);
+        }
+        return result;
+    }
+
+    private List<ItemStack> offerFor(ServerPlayer player) {
+        return player == first ? firstOffer : secondOffer;
+    }
+
+    private static List<ItemStack> inventorySnapshot(ServerPlayer player) {
+        List<ItemStack> result = new ArrayList<>(INVENTORY_SLOT_COUNT);
+        Inventory inventory = player.getInventory();
+        for (int i = 0; i < INVENTORY_SLOT_COUNT; i++) {
+            result.add(inventory.getItem(i).copy());
+        }
+        return result;
+    }
+
+    private static List<ItemStack> offerSnapshot(List<ItemStack> offer) {
+        List<ItemStack> result = new ArrayList<>(OFFER_SLOT_COUNT);
+        for (ItemStack stack : offer) {
+            result.add(stack.copy());
+        }
+        return result;
+    }
+}
--- a/src/main/java/com/trunksbomb/trade/trade/TradeStage.java
+++ b/src/main/java/com/trunksbomb/trade/trade/TradeStage.java
@@ -0,0 +1,6 @@
+package com.trunksbomb.trade.mod.trade;
+
+public enum TradeStage {
+    OFFERING,
+    CONFIRMING
+}
--- a/src/main/java/com/trunksbomb/trade/trade/TradeView.java
+++ b/src/main/java/com/trunksbomb/trade/trade/TradeView.java
@@ -0,0 +1,86 @@
+package com.trunksbomb.trade.mod.trade;
+
+import java.util.ArrayList;
+import java.util.List;
+import java.util.UUID;
+import net.minecraft.network.RegistryFriendlyByteBuf;
+import net.minecraft.network.codec.StreamCodec;
+import net.minecraft.world.item.ItemStack;
+
+public record TradeView(
+        UUID sessionId,
+        String selfName,
+        String otherName,
+        boolean debugMode,
+        TradeStage stage,
+        boolean selfAccepted,
+        boolean otherAccepted,
+        List<ItemStack> inventory,
+        List<Integer> reservedCounts,
+        List<ItemStack> selfOffer,
+        List<ItemStack> otherOffer) {
+
+    public static final int INVENTORY_SLOT_COUNT = 36;
+    public static final int OFFER_SLOT_COUNT = 36;
+
+    public static final StreamCodec<RegistryFriendlyByteBuf, TradeView> STREAM_CODEC = new StreamCodec<>() {
+        @Override
+        public void encode(RegistryFriendlyByteBuf buf, TradeView value) {
+            buf.writeUUID(value.sessionId);
+            buf.writeUtf(value.selfName);
+            buf.writeUtf(value.otherName);
+            buf.writeBoolean(value.debugMode);
+            buf.writeEnum(value.stage);
+            buf.writeBoolean(value.selfAccepted);
+            buf.writeBoolean(value.otherAccepted);
+            writeStacks(buf, value.inventory, INVENTORY_SLOT_COUNT);
+            writeInts(buf, value.reservedCounts, INVENTORY_SLOT_COUNT);
+            writeStacks(buf, value.selfOffer, OFFER_SLOT_COUNT);
+            writeStacks(buf, value.otherOffer, OFFER_SLOT_COUNT);
+        }
+
+        @Override
+        public TradeView decode(RegistryFriendlyByteBuf buf) {
+            return new TradeView(
+                    buf.readUUID(),
+                    buf.readUtf(),
+                    buf.readUtf(),
+                    buf.readBoolean(),
+                    buf.readEnum(TradeStage.class),
+                    buf.readBoolean(),
+                    buf.readBoolean(),
+                    readStacks(buf, INVENTORY_SLOT_COUNT),
+                    readInts(buf, INVENTORY_SLOT_COUNT),
+                    readStacks(buf, OFFER_SLOT_COUNT),
+                    readStacks(buf, OFFER_SLOT_COUNT));
+        }
+    };
+
+    private static void writeStacks(RegistryFriendlyByteBuf buf, List<ItemStack> stacks, int expectedSize) {
+        for (int i = 0; i < expectedSize; i++) {
+            ItemStack.OPTIONAL_STREAM_CODEC.encode(buf, stacks.get(i));
+        }
+    }
+
+    private static List<ItemStack> readStacks(RegistryFriendlyByteBuf buf, int expectedSize) {
+        List<ItemStack> stacks = new ArrayList<>(expectedSize);
+        for (int i = 0; i < expectedSize; i++) {
+            stacks.add(ItemStack.OPTIONAL_STREAM_CODEC.decode(buf));
+        }
+        return stacks;
+    }
+
+    private static void writeInts(RegistryFriendlyByteBuf buf, List<Integer> values, int expectedSize) {
+        for (int i = 0; i < expectedSize; i++) {
+            buf.writeVarInt(values.get(i));
+        }
+    }
+
+    private static List<Integer> readInts(RegistryFriendlyByteBuf buf, int expectedSize) {
+        List<Integer> values = new ArrayList<>(expectedSize);
+        for (int i = 0; i < expectedSize; i++) {
+            values.add(buf.readVarInt());
+        }
+        return values;
+    }
+}
--- a/src/main/resources/assets/trade/lang/en_us.json
+++ b/src/main/resources/assets/trade/lang/en_us.json
@@ -0,0 +1,5 @@
+{
+  "trade.trade.title": "Trading Screen",
+  "trade.trade.offer": "Offer screen",
+  "trade.trade.confirm": "Confirmation screen"
+}
--- a/src/main/resources/assets/trade/textures/gui/trade.png
+++ b/src/main/resources/assets/trade/textures/gui/trade.png
--- a/src/main/templates/META-INF/neoforge.mods.toml
+++ b/src/main/templates/META-INF/neoforge.mods.toml
@@ -0,0 +1,95 @@
+# This is an example neoforge.mods.toml file. It contains the data relating to the loading mods.
+# There are several mandatory fields (#mandatory), and many more that are optional (#optional).
+# The overall format is standard TOML format, v0.5.0.
+# Note that there are a couple of TOML lists in this file.
+# Find more information on toml format here:  https://github.com/toml-lang/toml
+
+# The name of the mod loader type to load - for regular FML @Mod mods it should be javafml
+modLoader="javafml" #mandatory
+
+# A version range to match for said mod loader - for regular FML @Mod it will be the FML version. This is currently 2.
+loaderVersion="${loader_version_range}" #mandatory
+
+# The license for you mod. This is mandatory metadata and allows for easier comprehension of your redistributive properties.
+# Review your options at https://choosealicense.com/. All rights reserved is the default copyright stance, and is thus the default here.
+license="${mod_license}"
+
+# A URL to refer people to when problems occur with this mod
+#issueTrackerURL="https://change.me.to.your.issue.tracker.example.invalid/" #optional
+
+# A list of mods - how many allowed here is determined by the individual mod loader
+[[mods]] #mandatory
+
+# The modid of the mod
+modId="${mod_id}" #mandatory
+
+# The version number of the mod
+version="${mod_version}" #mandatory
+
+# A display name for the mod
+displayName="Trading Screen" #mandatory
+
+# A URL to query for updates for this mod. See the JSON update specification https://docs.neoforged.net/docs/misc/updatechecker/
+#updateJSONURL="https://change.me.example.invalid/updates.json" #optional
+
+# A URL for the "homepage" for this mod, displayed in the mod UI
+#displayURL="https://change.me.to.your.mods.homepage.example.invalid/" #optional
+
+# A file name (in the root of the mod JAR) containing a logo for display
+#logoFile="examplemod.png" #optional
+
+# A text field displayed in the mod UI
+#credits="" #optional
+
+# The authors of the mod, displayed in the mod UI (optional)
+authors="trunksbomb"
+
+# The description text for the mod (multi line!) (#mandatory)
+description='''
+RuneScape-style player trading with ghost item offers and a two-step confirmation flow.
+'''
+
+# The [[mixins]] block allows you to declare your mixin config to FML so that it gets loaded.
+#[[mixins]]
+#config="${mod_id}.mixins.json"
+
+# The [[accessTransformers]] block allows you to declare where your AT file is.
+# If this block is omitted, a fallback attempt will be made to load an AT from META-INF/accesstransformer.cfg
+#[[accessTransformers]]
+#file="META-INF/accesstransformer.cfg"
+
+# The coremods config file path is not configurable and is always loaded from META-INF/coremods.json
+
+# A dependency - use the . to indicate dependency for a specific modid. Dependencies are optional.
+[[dependencies.${mod_id}]] #optional
+    # the modid of the dependency
+    modId="neoforge" #mandatory
+    # The type of the dependency. Can be one of "required", "optional", "incompatible" or "discouraged" (case insensitive).
+    # 'required' requires the mod to exist, 'optional' does not
+    # 'incompatible' will prevent the game from loading when the mod exists, and 'discouraged' will show a warning
+    type="required" #mandatory
+    # Optional field describing why the dependency is required or why it is incompatible
+    # reason="..."
+    # The version range of the dependency
+    versionRange="[${neo_version},)" #mandatory
+    # An ordering relationship for the dependency.
+    # BEFORE - This mod is loaded BEFORE the dependency
+    # AFTER - This mod is loaded AFTER the dependency
+    ordering="NONE"
+    # Side this dependency is applied on - BOTH, CLIENT, or SERVER
+    side="BOTH"
+
+# Here's another dependency
+[[dependencies.${mod_id}]]
+    modId="minecraft"
+    type="required"
+    # This version range declares a minimum of the current minecraft version up to but not including the next major version
+    versionRange="${minecraft_version_range}"
+    ordering="NONE"
+    side="BOTH"
+
+# Features are specific properties of the game environment, that you may want to declare you require. This example declares
+# that your mod requires GL version 3.2 or higher. Other features will be added. They are side aware so declaring this won't
+# stop your mod loading on the server for example.
+#[features.${mod_id}]
+#openGLVersion="[3.2,)"