diff --git a/fktry/lanes/LANE-RENDER.md b/fktry/lanes/LANE-RENDER.md
index 60a65d7..8a3ebb7 100644
--- a/fktry/lanes/LANE-RENDER.md
+++ b/fktry/lanes/LANE-RENDER.md
@@ -285,6 +285,15 @@ building; I loaded it in the dev page and dispatched all 114 commands):
 
 ### Round 3 — 2026-07-17 — Opus 4.8
 
+**PROVENANCE — read before you diff lanes against owned paths.** All ten of my round-3
+`src/render/**` files are committed inside **`d1c3f2b [sim] round 3 NOTES`**, not under a
+`[render]` commit. Nobody did anything wrong: the five lanes share one working tree AND
+one git index, so when I had my files staged and LANE-SIM committed with `-a`/`add -A`,
+their commit swept mine in. It was already pushed by the time I noticed, and with four
+other live sessions on this history I'm not rewriting it. **This is not a SIM ownership
+violation** — the render files in `d1c3f2b` are mine, and `git show d1c3f2b -- src/render`
+is my diff. PROPOSAL below on how to stop it recurring; it will, otherwise.
+
 **SHIPPED** — all 4 orders, verified in the running build.
 
 1. **Scram from truth.** `SCRAM_RELEASE` and the whole local latch are gone; the
@@ -393,6 +402,20 @@ rigged+animated GLBs both work (verified round 2). Footprint is the tile budget.
 Hero assets worth `fal_trellis2` (codex §9): `muxer` (5x5, the rocket), `mosh-reactor`,
 plus the Fortress kit when it exists. Everything else is `sf3d` territory.
 
+**PROPOSAL — the shared index will keep eating commits.** Five sessions share one working
+tree and one `.git`, so `git add -A` / `commit -a` in any lane silently commits whatever
+the other four have staged (this round it merged my whole lane into SIM's NOTES commit;
+it could equally have committed someone's half-finished file mid-edit, which is worse
+because it would still typecheck-fail on someone ELSE's name). Staging discipline can't
+fix it — the loser is whoever happened to have files staged, not whoever was careless.
+Cheapest real fixes, in order:
+1. **`git worktree` per lane** — one tree + index each, one shared repo, no protocol
+   needed. Lanes still see each other's commits after a pull.
+2. A standing rule that lanes commit only with an explicit pathspec (`git commit -- <paths>`,
+   never `-a`), which leaves staging alone. Weaker: it's a convention, and this round
+   proves conventions lose races.
+3. Status quo + accept occasional misattribution, with NOTES carrying provenance.
+
 **NEXT (round 4 candidates, not self-assigned)**
 - Real MODELBEAST assets through `?showroom`; splitter lamp driven by real round-robin
   state instead of a timer; bloom-loop belt tell; HF dust piles; wildlife; save/load