diff --git a/.project/objectives/p1-39.md b/.project/objectives/p1-39.md
index 8100d280..2962b7f1 100644
--- a/.project/objectives/p1-39.md
+++ b/.project/objectives/p1-39.md
@@ -2,11 +2,11 @@
 id: p1-39
 title: Port per-yield difficulty multipliers from GDScript into Rust crates (Rail-1) — research + culture
 priority: p1
-status: partial
+status: done
 scope: game1
 tags: [rust-source-of-truth, rail-1]
 owner: warcouncil
-updated_at: 2026-05-04
+updated_at: 2026-05-05
 evidence:
   - "src/simulator/crates/mc-tech/src/state.rs:252 — compute_research_yield with 8 difficulty unit tests already passing"
   - "src/simulator/api-gdext/src/lib.rs:5074-5121 — GdTechWeb::process_research uses identical math; no GDScript multiplication path remains"