# MEMORY.md

Shared working memory between sessions and collaborators. Short, dated entries with evidence: the command, the log line, or the file path.

Scope: facts and traps that cost time to establish. Planned work lives in [ROADMAP.md](ROADMAP.md); formal setup, pins, and licensing live in [Docs/](Docs/).

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## 2026-11-07 — Unreal Engine 5.8.4

- **Extracted** to `/run/media/system/DATA/Engines/UE_5.8.4` (73 GiB, `unzip` exit 0). CL `58902052`, `++UE5+Release-5.8`.
- **Gotcha: the editor needs a writable `~/.config/Epic`.** In the agent shell it crashed with signal 11 twice and looked like a broken install. The log named it:
  `create dir('/home/zwitschi/.config/Epic/') failed: errno=30 (Read-only file system)` →
  `Fatal error: Failed to create Intermediate directory '…/.config/Epic/UnrealEngine/5.8/Intermediate/'`.
  Rerunning with `HOME=/tmp/uehome XDG_CONFIG_HOME=/tmp/uehome/.config` reached `LogInit: Display: Engine is initialized.`
- **Vulkan RHI is still unproven.** The successful run used `-NullRHI`. Untested: `UnrealEditor -vulkan` from a desktop terminal.
- A packaged game does not need `~/.config/Epic`, so this failure does not follow the build.

## 2026-11-07 — Agent shell limits

- The agent shell has a **read-only home** and read-only `/run`: `sudo` is blocked (`no new privileges`), `flatpak run` and `podman` cannot create instances, `/dev/nvidia*` is absent so `nvidia-smi` always fails there. None of this is a broken machine; verify GPU things from a normal terminal.
- Anything outside the session workspace (`/run/media/system/DATA/Engines`, `/tmp`) needs the wider sandbox with an approval prompt.

## 2026-11-07 — Reference photography

- **Licensing is not a gate for local development.** Reference images live in the gitignored `Art/reference/` and are never committed. What each set establishes is written into `Docs/reference-notes-hollywood.md`.
- **Commons text search runs dry; categories do not.** `Tools/commons_fetch.py --category "Category:Hollywood Masonic Temple"` surfaced 15 files a search never showed, including 4–5k px façades.
- **`upload.wikimedia.org` throttles hard.** Batches of six or fewer with `--delay 3`; a throttled file is skipped and recorded rather than killing the run (HTTP 429).
- **Unqualified queries return junk.** `Hollywood Boulevard shops` returned a Münster street, `Hollywood Masonic Temple entrance` a Seattle card index. Check the hit list before accepting a set.
- **OpenRouter web search is expensive.** One `gpt-5.2` + `openrouter:web_search` call ran 17 searches and cost **$0.38**; two of its eight URLs were Commons files already held. Use it for a known gap, not a sweep. `Tools/page_image_fetch.py` turns results into files by reading `og:image`.
- **The inherited "eight stone steps, 12 m wide" is wrong.** Photographs show three portals, each with its own short flight. Do not copy that number into geometry.

## 2026-11-06 — Blender and Blosm, headless

- **`flatpak run` does not work here.** Call the binary inside the app tree:
  `B=/var/lib/flatpak/app/org.blender.Blender/x86_64/stable/active/files`, then `LD_LIBRARY_PATH="$B/blender/lib" "$B/blender/blender" -b …` with `BLENDER_USER_SCRIPTS="$HOME/.var/app/org.blender.Blender/config/blender/5.2/scripts"`.
- **Blosm needs two headless workarounds**, both already in `Tools/blosm_blockout.py`:
  1. it refuses to import until an asset directory is set, and the check fires before the mode is honoured;
  2. in background mode the default level table is empty, and the add-on then takes a path with a broken relative import (`from gui import addDefaultLevels`). Seeding one entry avoids it.
- **Blosm projects on a sphere, not an ellipsoid.** Its frame is about 0.4 % oversized and rotated by meridian convergence — roughly 2 m at the theatre. Fixed with a six-parameter affine into EPSG:26911 (0.0 cm residual).
- **Transform roots only.** 256 of 275 objects are children; transforming both parent and child applies the correction twice and reads as a 2 m placement error.
- **Blosm quietly fetches from Overpass** for relation members missing from the extract. `loadMissingMembers` is off by default in the tool so imports stay offline and reproducible.

## 2026-11-06 — Geo data traps

- **The 3DEP export is a tiled TIFF, not strips.** A strip reader silently scrambles rows and produces fake 0 m / 127 m bands. `Geo/scripts/dem_stats.py` handles tiles.
- **Sample walk routes through PROJ.** Placing samples with the OSM spherical approximation put them metres off the UTM meshes and reported 91 phantom holes. `/tmp` is not shared between tool calls here either — regenerate instead of saving intermediate files there.
- **3DEP cannot resolve kerbs.** Sharpest break near the kerb line is 0.09–0.12 m/m, a gutter transition, not a 0.15 m upstand. Kerb height stays a stated assumption.
- **Building interiors are not ground.** Points inside the hero footprint returned 114.5–117.1 m — structure, not terrain. Excluded from the relief figure.
- Two measurements independently agree on the carriageway: crossing length 20.9 m and gutter spacing −10 / +10…12 m.

## 2026-11-06 — Repository traps

- **Without `git lfs install` the lfs filter is inactive and `git add` does not warn** — it stores the file as a plain blob. `Tools/check-lfs.sh` is the guard.
- **Never commit reference images or `.env`.** `.gitignore` covers `/Art/reference/`, `.env`, `*.env`. When images slipped in early, history was rewritten to remove them.
- The project origin is Hollywood × Highland: `E 376 515.389 / N 3 774 224.083` in EPSG:26911. Blender X east, Y north, Z up, metres, Z measured from the origin ground (NAVD88 115.911 m). The whole block sits at negative X.