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transcience/CLAUDE.md
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claude de48afcbd9
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Fix aiming under a scrolling camera; add status and decisions docs
The aim bug was collateral from the camera work. "Mouse relative to the centre
of the screen" WAS the cursor's world position while the world was drawn fixed
at the origin, so subtracting the player position gave the right vector. Once
the camera scrolled, that expression became the aim vector itself, and
subtracting the player position again made the ship aim at a fixed world
location -- walking around swung the crosshair with the mouse held still.

Fixed by inverting the transform the view actually draws with (world = screen -
world_view.position, published by the game scene each frame) rather than
assuming the player is centred, so it still holds if the camera later clamps at
map edges or gets shake or look-ahead. tests/unit/test_aim.gd pins it, including
the regression directly: moving the player must not move the crosshair.

Documentation, for other sessions picking this up cold:
- docs/ROADMAP.md rewritten as the status map -- every feature in the brief
  against its state and the file implementing it, the known gaps called out
  (actor interest management is the notable one), and the ten design questions
  that are genuinely unspecified and should not be guessed at.
- docs/DECISIONS.md, new: settled decisions with their reasoning, so a session
  does not re-litigate or re-ask. Several are not the obvious default -- no
  i-frames, no contact damage, non-interruptible escape, and never sending the
  map seed.
- CLAUDE.md and README point at both.

137 tests; check.sh, test.sh and smoke.sh pass.
2026-09-03 20:58:03 +02:00

165 lines
8.8 KiB
Markdown

# Transcience
Top-down twin-stick bullet-hell with a dedicated, server-authoritative backend.
Godot 4.7, GDScript only. One executable is both server and client.
**Starting a new session?** [docs/ROADMAP.md](docs/ROADMAP.md) says what is
built, what is next, and which file implements each feature.
[docs/DECISIONS.md](docs/DECISIONS.md) records what the user has already decided
and why — read it before asking a design question, several answers there are not
the obvious default.
## Commands
```bash
tools/check.sh # parse-check every script (~5s) -- run after every edit
tools/test.sh # GUT suite, headless (~2s)
tools/smoke.sh # real server + 2 bot clients over ENet (~35s)
tools/bench.gd # godot --headless --path . --script tools/bench.gd
tools/server.sh # dedicated server
tools/client.sh --join --name ada
```
Everything after `--` goes to `GameOpts.parse()`:
| Flag | Effect |
| --- | --- |
| `--server` | Dedicated server, no view. |
| `--join` | Skip the menu and connect. |
| `--listen` | Skip the menu and host a listen server with a local player. |
| `--bot` | Scripted input instead of the keyboard. Implies `--join`. |
| `--host`, `--port`, `--name` | Connection details. |
| `--autoquit N` | Quit after N physics ticks. |
| `--boss-rush` | Server-side: dungeons spawn the boss and no trash. |
| `--depth N` | Server-side: depth of new dungeons, which drives map size. |
| `--verbose` / `--quiet` | Log level. |
A change is done when `check.sh`, `test.sh` and — if it touched networking,
instances or the simulation — `smoke.sh` all pass. Say so explicitly; do not
report a networking change as working on the strength of unit tests alone.
## Hooks
`tools/install-hooks.sh` once per clone (points `core.hooksPath` at
`.githooks/`, committed in the repo — plain bash, no `pre-commit` framework, so
cloning costs nothing extra to run tools/*.sh). Own `.gd` files (not vendored
`addons/`) trigger `check.sh` + `test.sh` on commit (~7s); `smoke.sh` runs on
push (~35s, skip deliberately with `SKIP_SMOKE_HOOK=1 git push`).
## The one rule
**The server decides everything; the client only sends intent.**
A client can send exactly two things: an [InputFrame] (move vector, aim angle,
three button bits) and a handshake. There is no message for "I moved here", "I
hit that", "I took damage" or "my escape finished". Adding one would collapse
the whole security model, so don't — validate-after-the-fact is strictly weaker
than having no code path at all.
`SimWorld.authoritative` is `true` on the server and `false` on the client. In
replica mode the world runs no AI, fires no emitters and resolves no hits; it
only integrates bullets it was told about. `tests/unit/test_server_authority.gd`
and `tests/integration/test_replica_parity.gd` pin this down.
## Layout
| Path | What lives there |
| --- | --- |
| `src/sim/` | The whole game as plain RefCounted objects. No nodes, no physics server, no rendering. |
| `src/sim/patterns/` | Bullet emitters — the authoring surface for every enemy and boss. |
| `src/sim/map_grid.gd` | Tile grid: collision, line of sight, chunk streaming. |
| `src/sim/map_gen.gd` | Dungeon generation; `build()` is the only entry point. |
| `src/content/rooms.gd` | Hand-authored room stamps (hub, boss arenas) as text. |
| `src/content/content.gd` | All enemies and bosses, defined in code. Source of truth. |
| `src/net/` | Codec, `ServerRuntime`, `ClientRuntime`. |
| `src/instances/` | Lobby hub and dungeon runs. |
| `src/view/`, `src/ui/` | Read-only rendering. Never decides anything. |
| `src/autoload/net.gd` | The only autoload. RPC surface. |
| `tools/` | Headless tooling. |
The simulation must not import anything from `src/net/`, `src/view/` or
`src/ui/`, and must not touch `Net`. That is what lets tests drive a thousand
ticks in milliseconds with no SceneTree.
## Godot gotchas that will waste your time
1. **New `class_name` needs a cache refresh.** `.godot/global_script_class_cache.cfg`
is only rebuilt by the editor or `godot --headless --path . --import`.
Until then every use of the new class reports `Identifier not declared`,
which looks like a real error. `check.sh` does the refresh for you.
2. **Autoload names do not resolve under `--script`.** A `--script` run has no
main loop, so `Net` is `Identifier not found`. Tools that need autoloads must
run as a scene (see `tools/check.tscn`); tools that don't can use `--script`.
This is why `GameLog` and `GameOpts` are static classes rather than autoloads.
3. **`ResourceLoader.load()` returns non-null for a broken script.** Never test
the return value to detect a parse error; read the engine's stderr instead.
And never call `Script.reload()` on the script you are running — it hangs.
4. **Input events default to `device = 16`, which matches nothing.** Bindings
must use `device = -1`. `tools/setup_input_map.gd` generates the input map
correctly; edit that file, not the `[input]` block in `project.godot`.
5. **`set_anchors_preset(preset)` does not zero the offsets.** `keep_offsets`
defaults to `false`, which despite the name means "recompute offsets to keep
the control's *current* rect on screen" — for a freshly created Control that
rect is `(0,0)`-sized, so it comes out pinned to the top-left corner
regardless of the anchors. Use `set_anchors_and_offsets_preset()` for any
Control built in code. Separately: `.position` assigns an *absolute*
coordinate even on an anchored control; `offset_left`/`offset_top` are the
anchor-relative ones. This combination silently broke the main menu and
three pieces of the HUD.
6. **`ProjectSettings.save()` drops settings equal to the engine default** and
strips comments. Anything load-bearing (the 60 Hz tick) is asserted in code
in `src/main.gd` instead of trusted to `project.godot`.
## Non-obvious invariants
- **`ClientRuntime.process_physics_priority = -10`.** The client must sample and
send input before `ServerRuntime` ticks, or a listen server's drawn ship sits
a permanent tick ahead of the authoritative one and bullets trail it. Measure
with `godot --headless --path . res://tools/diag_prediction.tscn` (~0.1px is
healthy, 4px means the ordering broke).
- **`PLAYER_RADIUS` (hitbox) < `PLAYER_VISUAL_RADIUS` (sprite), and
`PLAYER_MUZZLE_OFFSET` derives from the visual one.** Prefer a visible
near-miss over an invisible hit; keep the muzzle clear of the sprite.
- **`INPUT_MAX_LEAD` must stay well above `INPUT_LEAD_MAX`.** The server's
input acceptance window has to be wider than the band in which the client
re-syncs its own numbering. Violate it and drifting clocks land in a silent
dead zone where the server rejects everything and the client never notices —
the ship and the authoritative position separate permanently. Pinned by
`tests/unit/test_input_lead.gd`.
- **Never send the map, or its seed.** Geometry is streamed per peer in chunks
around that peer's player (`ServerRuntime._stream_map`). The seed would let
any client regenerate the whole dungeon. `MAP_STREAM_RADIUS` must stay wider
than `FOG_VIEW_RADIUS`, or prediction runs on terrain the client lacks.
- **Bullet speed must stay under one tile per tick.** Wall collision samples
position once per tick, so anything faster tunnels. Pinned by
`test_bullet_speeds_stay_below_the_tunnelling_threshold`.
- **No contact damage.** Every enemy threatens through bullets only; touching
one is harmless. `tests/unit/test_content.gd` enforces that every hostile has
an emitter.
- **No i-frames.** Every bullet that touches a player lands; `spawn_grace` is
the only invulnerable state. Do not reintroduce post-hit immunity — it makes
dense patterns safer than sparse ones.
- **A disconnect is not an exit.** Dropping in a dungeon keeps the player in the
world as `linkdead`, channelling out over the same second the escape costs.
Damage must never cancel the escape channel, or quitting beats the button.
See [docs/NETCODE.md](docs/NETCODE.md).
## Adding content
A new enemy or boss is data, never code. Add a builder to
`src/content/content.gd` returning an `EnemyDef` / `BossDef` made of the
emitters in `src/sim/patterns/`, register its id in `enemy()` / `boss()`, and
add a test. `tests/unit/test_boss.gd::test_a_brand_new_boss_needs_no_engine_changes`
builds a boss from scratch and asserts the simulation needs no changes to run
it — if you find yourself adding a per-boss branch to `SimWorld`, stop and add
an emitter type instead.
`tools/export_content.gd` writes `.tres` copies into `resources/` for tuning in
the editor inspector. Those are an export, not the source; port changes back.
## Style
Typed GDScript everywhere (`untyped_declaration` is a warning). Tabs, snake_case
files, `PascalCase` class names. Comments explain *why* a thing is the way it is —
the netcode and anti-cheat decisions especially. Keep the existing density.