Modded Update 3 save cannot be recovered to Update 4 — Recovery Save system requ

I have a save from Update 3 (game version 0.7.9a, build 500) that used three mods: COIExtended.Cheats, COIExtended.Difficulty, and COIExtended.Tweaks (mod assembly version 0.7.9.500). After updating to Update 4, the save no longer loads, and I haven't been able to find a working path to bring it forward using the tools currently available to me.

What I've tried

1. Loading directly on the current Update 4 branch (0.8.7a) — fails immediately, mods aren't recognized (Loaded mods: none), and the game throws a CorruptedSaveException while deserializing UnlockedProtosDb (a RocketTransporterProvider object is read where an Event was expected). This looks like a stream desync caused by mod-added save data that the base game doesn't know how to parse without the originating mod code loaded.
2. Following the documented Recovery Save process (Captain's Diary #55) via the v0-8-2-legacy-recovery branch (game version 0.8.2c) to run export_recovery_save. Same result — my mod build (targeting 0.7.9.500) isn't recognized as compatible on 0.8.2c, so nothing loads and there's nothing to export.

As I understand it, the Recovery Save workflow depends on having some compatible build of the save's mods available on a 0.8.2+ branch, even if it isn't the exact original version, so the save can be loaded once and exported before the missing-mod data causes a hard failure. That bridge is what let this work for other mods/mod versions. For COIExtended specifically, that bridge is no longer available through official channels, so there's currently no version of the game where both (a) my mods will load, and (b) the recovery export tooling exists.

Is there an official path, tool, or process for recovering a save in this situation?

Happy to attach my save file if that helps with diagnosis. Thanks for taking a look.

having gone through the recovery process, unfortunately i don't think so

As of now, i don't know of any way to recover saves without loading the save itself. A frustrating wall, but it's the unfortunate truth

You need those mods to load the save, if you can get your hands on a version you could try manually installing them. It might not be stable but it could work

Otherwise? you're out of luck :(