v0.4.0 experimental - 22 shared items and action recovery

v0.4.0 experimental

Shared pickup now covers 22 persistent items, using the installed game's save references to keep duplicate axes, buckets and dippers distinct. See docs/SHARED_ITEM_CATALOGUE.md in the ZIP for the exact list.

This build also adds:

• Ordered live update batches and fair scheduling for moving items.
• Retries of the original action ID when a reply is delayed; input waits for the committed result.
• Correlated walking correction, accepted remote-player positions and one pose sender.
• Host continuity when an invalid peer is disconnected.
• Updated local feedback coverage and the combined end-of-build checklist.

Both players must install this same ZIP while the game is closed. Retain each PC's original disposable-profile preparation folder/journal and keep Steam Cloud off until restoration is verified. No game binaries, personal saves, local reports or profile backups are included.

Validation: 6,936 automated C# assertions, 16 tooling fixtures, 19 profile-recovery fixtures, and a metadata check against the shipped legacy game libraries. The world tests use real localhost UDP with synthetic entities. The item bindings were checked against the installed scene's persistent references and body layout. These are not actual multiplayer game tests.

Full-game multiplayer remains unfinished. Special item use/factories, other vehicles, passengers, wheel/door/damage state, Satsuma assembly, shops/jobs, needs/death, weather/NPCs and coherent vanilla saves are not implemented. The Hayosiko supports the existing driver/body experiment only. Manual two-PC validation is still pending; the complete current procedure is docs/PLAYER_CHECKS.md in the ZIP.

Download the attached mod ZIP, not GitHub's automatically generated source archive.

v0.3.0 experimental - shared cup and Hayosiko adapter

This experimental build adds a shared coffee-cup adapter and Hayosiko driver/body adapter. It is not full-game multiplayer, and actual two-PC gameplay has not been verified. Manual game tests are deferred until the user's end-of-build testing.

Implemented:

• Host-authorized coffee-cup pickup, carrying, drop and throw, with body orientation/spin and a late-join baseline.
• One Hayosiko driver, seat request/replay checks, configured driving controls, held starter on I, stale-input braking and disconnect cleanup. Client body presentation blends toward host state.
• Male/female characters with walking, carrying and seated poses, automatic startup in shared mode, and local F7/error feedback.
• A legacy .NET UDP address-cache race fix: the old implementation could deliver a packet to the wrong client and stall bootstrap/commits. The previous source fails the new three-client regression; the fixed source passes 100,800 addressed payloads across sequence wrap.

Both PCs must update to this exact package and choose the same Shared world mode. The game must be closed during DLL replacement. This PC's package contains only the mod DLL, documentation, hashes, third-party notices and profile tool; it contains no game binaries or saves.

Shared mode requires an already prepared disposable profile. Preserve any existing preparation journal and original backup; do not prepare an already active profile again from this new ZIP. Keep Steam Cloud off until normal quit, restoration and verification.

Only the cup and van body/driver are mapped. Native pickup/cup use and unsupported van FSMs are gated during the session. Other items and vehicles, passengers, doors/dashboard/wheel/damage state, assembly, shops/jobs, needs/death, weather/time/NPCs and coherent vanilla shared saves are unfinished.

Validation: 6,869 legacy C# assertions, 16 tooling scenarios, 19 profile fixtures, and a metadata audit resolving 249 types / 857 members against the shipped game libraries. GitHub headless checks passed for the implementation commit 860027c. These are not game-runtime test results.

Install/update instructions · Manual checklist for when ready · Known limitations

Download MSC-MP-Mod-0.3.0-experimental.zip below; GitHub's source-code ZIP does not contain the compiled mod.

MSC-MP v0.2.2 - Runtime and reconnect fixes

Additional reconnect fix

Version 0.2.2 includes the missing-runtime-type fix and retires old peers before disconnect callbacks, preventing cleanup from removing replacement connections. Your local PC has been updated; your friend must use this same release.

Connection compatibility hotfix

Both players must update from 0.2.0. The reported host disconnect was caused by a reference to System.IO.InvalidDataException, which does not exist in the game's shipped runtime. The protocol, world-sync and checkpoint paths now use the supported FormatException type while preserving malformed-data rejection.

The shipped-library audit also found and removed an unsupported console-color setter and FileStream constructor. Checkpoint publication still flushes buffers and uses atomic replacement; physical power-loss durability is not guaranteed.

Install

Download MSC-MP-Mod-0.2.2-experimental.zip. With the game closed, replace only Mods/MSCMP.Mod.dll in the MSCLoader-selected Mods directory on both PCs. The developer's local PC has already been updated.

Keep any active test-profile journal and original-save backup. Use the folder that prepared your existing profile for its eventual restoration. Do not prepare a second profile from the new ZIP. See the installation/update guide.

Verified

• 4,463 legacy C# assertions, including real localhost UDP handshake, packet rejection, replication and checkpoint tests.
• 16 deployment/package scenarios and 19 isolated profile-recovery assertions.
• Regression check: the new runtime API audit rejects the previous DLL for the missing APIs.
• Corrected DLL: all 239 type and 748 member references resolve against the shipped game libraries.
• Built, tested, installed and packaged mod DLL hashes match.

DLL SHA-256: DC98DB55BAE14674DD596B381C9E7FCCCF2A7920E2F2E3CF8621DE446D4828BC

Retest

Both players load their disposable GAME profiles first. Host on UDP 20577, then have the friend join using the host's Tailscale IPv4 address. Confirm peer acceptance and try Ping. Press F7 if it fails.

Actual two-PC game confirmation of this fix is pending. The callback/endpoint-cleanup reconnect race is corrected and covered by a deterministic regression plus five successful UDP stress runs. Other delayed-packet/endpoint-reuse behavior is not guaranteed. Repeated synthetic-world tests exposed a separate intermittent baseline stall; this remains under investigation before shared gameplay is enabled. This remains an experimental networking/character-preview build; shared items, vehicles, assembly and world saves are not implemented.

MSC-MP v0.2.1 - Connection compatibility hotfix

Connection compatibility hotfix

Both players must update from 0.2.0. The reported host disconnect was caused by a reference to System.IO.InvalidDataException, which does not exist in the game's shipped runtime. The protocol, world-sync and checkpoint paths now use the supported FormatException type while preserving malformed-data rejection.

The shipped-library audit also found and removed an unsupported console-color setter and FileStream constructor. Checkpoint publication still flushes buffers and uses atomic replacement; physical power-loss durability is not guaranteed.

Install

Download MSC-MP-Mod-0.2.1-experimental.zip. With the game closed, replace only Mods/MSCMP.Mod.dll in the MSCLoader-selected Mods directory on both PCs. The developer's local PC has already been updated.

Keep any active test-profile journal and original-save backup. Use the folder that prepared your existing profile for its eventual restoration. Do not prepare a second profile from the new ZIP. See the installation/update guide.

Verified

• 4,459 legacy C# assertions, including real localhost UDP handshake, packet rejection, replication and checkpoint tests.
• 16 deployment/package scenarios and 19 isolated profile-recovery assertions.
• Regression check: the new runtime API audit rejects the previous DLL for the missing APIs.
• Corrected DLL: all 239 type and 748 member references resolve against the shipped game libraries.
• Built, tested, installed and packaged mod DLL hashes match.

DLL SHA-256: 360184D3D47E9703081A4DF515211AF24EDD52731A793CB1A174117E6EC23C2D

Retest

Both players load their disposable GAME profiles first. Host on UDP 20577, then have the friend join using the host's Tailscale IPv4 address. Confirm peer acceptance and try Ping. Press F7 if it fails.

Actual two-PC game confirmation of this fix is pending. The separately documented intermittent rapid-reconnect limitation remains open. This remains an experimental networking/character-preview build; shared items, vehicles, assembly and world saves are not implemented.

MSC-MP v0.2.0 - Experimental networking and character preview

Superseded: update both PCs to v0.2.1. This 0.2.0 build has a confirmed missing-runtime-type error that can stop networking during a connection attempt.

Experimental networking and character-preview build

This is an early test build, not complete playable multiplayer. Shared items, driving, assembly, economy and vanilla world saves are not synchronized.

Download and install

Download MSC-MP-Mod-0.2.0-experimental.zip below (not the automatic source-code archives). Each player needs their own My Summer Car installation and MSCLoader. Target: Steam build 20171487, Unity 5.0.0f4, MSCLoader 1.4.2.410.

Follow the installation and save-isolation guide before starting a disposable test game. Load the game first, then Host/Join over a private LAN/tailnet using the same package and UDP port 20577.

Included

• Host/Join/Leave diagnostics, compatibility checks, ping and reliable probes.
• Original male/female character meshes and portraits, optional walking-avatar preview.
• F7/manual-note problem reports stored locally; nothing is automatically uploaded.
• Read-only player/cup inspection and the reversible test-profile tool.
• Installation/testing documentation, build hashes and dependency license/notices.

The ZIP contains 29 allowlisted files, including only this mod's DLL as an executable binary. Game files, personal saves, private configuration and local recovery journals are excluded. SHA256SUMS.txt verifies the ZIP.

Evidence and open gates

The recorded legacy build passed 4,459 C# assertions, 16 deployment/package scenarios and 19 profile-recovery assertions. A fresh modern-host run failed a rapid disconnect/reconnect setup; a diagnostic rerun passed all 4,459 assertions. The intermittent reconnect timeout remains unresolved and documented.

Single-game logs show partial initialization, hosting, feedback and binding evidence. The observed join failed. Actual two-PC connections, character rendering and full runtime profile restoration still need verification. See known limitations and runtime evidence.

Mod DLL SHA-256: A50171456FCC29D61B53F1F7B1916E9F2CA34EC425DE41D3FB3700507BE0E35B

GitHub's headless, deployment/package and profile-fixture checks passed for the published source commit. They do not establish game-runtime success.