memory: record the shared-checkout commit race

The skill-pack entry was swept into another session's commit before it could be
committed on its own. Notes that a shared worktree can commit a shared file for
you - or drop the edit if the file is overwritten - and that git log -S is the
way to check before assuming the edit was lost.

MEMORY.md

@@ -155,6 +155,7 @@ Scope: facts and traps that cost time to establish. Planned work lives in [TODO.
 - **The AGENTS.md "MCP-driven" caveat is overstated.** 41 of 94 SKILL.md mention MCP, mostly only in the `description` line; the bodies are method guides (naming, proportions, validation checklists) that work headless. Do not skip a pack because it advertises MCP.
 - **Skill names in AGENTS.md/TODO.md all resolve** except `references`, which is the folder above, not a pack.
 - Symlinks are user-level: a fresh machine needs the same 94 links before the packs are loadable by name.
+- **A shared checkout can commit your uncommitted edit for you, or lose it.** This entry was written but not yet committed when another session ran a `git commit` that included `MEMORY.md`; it landed inside their commit (`54b6239`) with a message that does not mention it. Had they overwritten the file instead, the work would have been gone with no reflog to recover from. On a shared worktree, either commit a shared file immediately or check `git log -S` for it before assuming the edit is missing.
 
 
 ## 2026-11-07 — Street visibility and the LFS lockable trap