# Uefn Lessons > Shared cross-project knowledge base of recurring Verse/UEFN gotchas, MCP quirks, and coding mistakes, accumulated across every project set up with this kit. Read it before writing or debugging Verse code, or when investigating a compile/runtime error, to check whether it's already a known issue. Also the place to add a new entry when you discover something non-obvious that would help on future projects too, not just this one. - Skill: `mimmo-the-root/uefn-lessons` (Agent Skill) - Install (CLI): `npx skillmds@latest add mimmo-the-root/uefn-lessons` - Raw SKILL.md: https://api.skillmd.com/api/skills/mimmo-the-root/uefn-lessons/raw - Safety review: pending - Works with: Claude Code, Claude.ai, OpenAI Codex - Category: AI & ML - Author: mimmo-the-root (https://skillmd.com/u/mimmo-the-root) - Updated: 2026-09-22 - Page: https://skillmd.com/skills/mimmo-the-root/uefn-lessons --- # UEFN / Verse lessons learned This file is shared across every project set up with this kit — unlike per-project agent memory (`memory: project` in `coder`/`qa-regression`, which resets on every new island), entries here persist and apply everywhere. It only becomes useful if agents are disciplined about reading it before starting work and adding to it when they learn something new. Read it directly (`~/.claude/skills/uefn-lessons/SKILL.md`) at the start of a coding or debugging task, the same way you'd read `CLAUDE.md`. ## When to add an entry here vs. per-project memory - **Here** (this file): the lesson is about Verse, UEFN, or the MCP tooling itself — it would apply on any island, not just this one. Example: "`@editable` on a field whose type isn't `` fails to compile with a misleading 'Unknown identifier' error." - **Per-project memory** (`coder`'s or `qa-regression`'s own memory, see `~/.claude/CLAUDE.md` rule 10): the lesson is specific to THIS project's devices, assets, or design decisions and wouldn't mean anything on a different island. Example: "this project's RespawnManager ignores calls made before BeginPlay finishes." If in doubt, ask: "would this save me time on a different island?" If yes, it goes here, not in per-project memory. ## How to add an entry One line per lesson: symptom/cause, then how to recognize or avoid it. No long write-ups — the point is to save tokens and rediscovery time across 50 projects, not to build another document to maintain. Add new entries under the closest matching category below (add a new category if none fits — keep the same one-line style). Never delete or rewrite someone else's entry without being sure it's wrong; if a later project seems to contradict an existing entry, add a note next to it rather than silently overwriting it — the contradiction itself might be useful information (e.g. "only true for devices placed before v3x.x"). Remove the "(example — replace)" placeholder entries below once real ones are added; they're only there to show the expected format, not to be kept as real lessons. ## Verse syntax gotchas - (example — replace) `@editable` on a field whose type isn't marked `` fails to compile with "Unknown identifier" instead of a clear type error — check the type's persistability first whenever this error shows up on an `@editable` line. ## Device behavior surprises Device-TYPE-specific quirks (exact sizing math, orientation gotchas, and similar for `DemoDisplay`, Elimination Manager, Item Granter, Storm Controller, Player Spawner, and others) now live in `~/.claude/skills/uefn-device-gotchas/` instead of growing here — read that skill for device-specific behavior. Keep this category for genuinely generic device-handling surprises that don't fit a single device type. ## MCP / tooling quirks - (example — replace) `mcp__unreal-mcp__call_tool` is a single dispatcher tool for every action — if a call behaves unexpectedly, check the JSON payload you're sending, not just the tool name. - `get_actor_bounds` can be skewed by asymmetric components (e.g. a spotlight's cone), stretching the bounding box well past the actor's physical footprint on one side only. Don't trust it blindly for footprint/collision math — compute the "real" footprint from the actor's own set `width`/`depth`/`height` (symmetric around its location) instead, and use `get_actor_bounds` only to sanity-check the side you expect to be unaffected. - **Don't use `AssetTools.find_assets` on `/Game` to look for a project's own custom content** — in this kit's MCP/UEFN setup, that path never exposes the project's actual custom Verse/assets, even with the right project open in UEFN (it silently returns nothing useful instead of erroring, which is what makes this easy to miss and mistake for "the project has no custom content" or "MCP isn't seeing the right project"). The tool that actually lists the real project content is **`ValkyrieToolset.VerseToolset.ListFiles`** — use that whenever you need to see what Verse/ assets genuinely exist in the currently-open project, not `AssetTools.find_assets`. Confirmed by the owner directly testing both against the same open project. ## Performance pitfalls - (example — replace) ... ## Multiplayer pitfalls - (example — replace) ... ## Discover / retention signals Moved to the dedicated `~/.claude/skills/discover-retention/` skill (which also tracks validated proposal outcomes across projects, not just the static signal facts) — read that instead.