Deepgrain Foundry: move from a claude.ai artifact to a local repository

The game as of artifact version 24, ready for local development with
coding agents.

- Source split from three large files into 52 small ones under src/sim,
  src/render and src/ui, joined in the order in src/manifest.json by
  build.py. The joined code is unchanged apart from comments; every
  headless suite gives the same output, and screenshots in both looks
  are pixel-identical to before.
- Light tidying with no change in behaviour: one movement scan loop,
  shared hazard-stripe and belt shader helpers, unused code removed, a
  shared check helper for the test suites.
- World files can be exported as an ordinary download outside claude.ai.
- Tests: broken old scripts removed, experiments moved to tools/,
  test/run_all.py added. Tools: shot.py (repeatable screenshots),
  where.py, map.py.
- Docs: AGENTS.md, CLAUDE.md, NOTES.md (the owner's to-do inbox),
  docs/PROJECT_MAP.md, DESIGN.md, TESTING.md, systems notes, the
  owner's requests and an agent log.

Co-Authored-By: Claude Opus 5.5 <noreply@anthropic.com>
Claude-Session: https://claude.ai/code/session_01K9kLmYADKSEjuwUN3rFxDA

docs/agent-log.md

@@ -0,0 +1,53 @@
+# Agent log
+
+What agents have done, newest first. Add an entry for every piece of work: the date, which
+note or request it was for, what changed, the files touched, the tests run, and anything left
+open or not verified. Keep each entry short; the git history has the details.
+
+## 2026-10-23: export from claude.ai to a local repository (Claude, in claude.ai)
+
+Request: split the source into small files, deduplicate and tidy a little, test fully, and
+write the notes, docs and agent instructions for local development.
+
+- **Source split.**
+  - `core.js` (3,688 lines), `main.js` (2,012) and `render.js` (938) became 52 files in
+    `src/sim/`, `src/render/` and `src/ui/`, each with a header line. The build order lives in
+    `src/manifest.json`.
+  - Checked that the joined code was identical to before, apart from comments and blank lines.
+  - Every headless suite gave the same output, line for line, before and after.
+  - Screenshots of two scenes, in both looks, were pixel-identical before and after
+    (`tools/shot.py --freeze`).
+- **Tidying, behaviour unchanged.**
+  - One scan loop in `simMove` instead of two mirrored copies.
+  - A `drawHazardRims` helper replaced 3 copies.
+  - The belt and filter shader code shares `beltLineSD`, `bandRidge` and `bandColor`.
+  - Removed unused `refundCost`, `wakeArea`, `brushFor`, and the `PARTS` / `PART_BY_ID` aliases.
+  - The suites share `suite()` (check / done) from the harness, and failures now set the exit
+    code.
+- **Tests.**
+  - Six broken old scripts were deleted; they used functions removed long ago.
+  - Experiments and reports moved to `tools/experiments/`.
+  - `t_v2` / `t_v4` / `t_v9` were renamed `t_basics` / `t_world` / `t_conveyors`.
+  - Added `test/run_all.py`.
+- **Tools.**
+  - `tools/shot.py`: repeatable screenshots of a scene set up in JavaScript.
+  - `tools/where.py`: maps built-page line numbers back to source files.
+  - `tools/map.py`: the project map's index.
+  - `tools/scenes/`: example scenes.
+  - The game skips cursor previews when `GAME.hidePreviews` is set, for clean screenshots.
+- **World files outside claude.ai.**
+  - Pause → Export world file only worked inside claude.ai, through its downloads hook.
+  - It now falls back to an ordinary browser download (`exportWorld` in `src/ui/saves.js`).
+  - `test/play.py` checks that an exported file downloads and imports back on the title screen
+    as the same world.
+- **Build.** `build.py` writes `dist/index.html` (a full page), `dist/deepgrain-foundry.html`
+  (the same without the document wrapper, as the claude.ai artifact used) and
+  `dist/bundle-lines.json`.
+- **Docs.** `AGENTS.md`, `CLAUDE.md`, `README.md`, `NOTES.md`, `docs/PROJECT_MAP.md`,
+  `docs/DESIGN.md`, `docs/TESTING.md`, `docs/systems/*`, `docs/history/requests.md`.
+- **Tests run.** All 11 headless suites pass, as do `test/play.py` (101 checks) and
+  `test/t_smooth.py` (8 checks).
+- **Open.**
+  - The owner reports that big piles on belts still only move at the top (NOTES.md); not yet
+    reproduced.
+  - The game's last claude.ai artifact was version 24.