transcience/docs/DECISIONS.md

# Settled decisions

Design choices the user has already made, with the reasoning. **Check here
before asking** — re-litigating a settled decision wastes a round trip, and
several of these look like defaults you would otherwise pick differently.

Ordered newest last.

---

## Simulation shape

**Game logic lives in plain `RefCounted` objects, not nodes.** No
`CharacterBody2D`, no `Area2D`, no physics server. Bullet counts make per-bullet
nodes unaffordable, the dedicated server allocates nothing, and the whole suite
runs with no `SceneTree`. Full reasoning in [ARCHITECTURE.md](ARCHITECTURE.md).

**Content is GDScript, not `.tres`.** A boss is a readable diff, there are no
resource UIDs churning in version control, and a test can build content inline.
`tools/export_content.gd` writes `.tres` copies for inspector tuning, but code
is the source of truth — port inspector edits back.

---

## Netcode

**The client sends input and nothing else.** No message exists for position,
hits, damage, or a finished escape. Having no code path is strictly stronger
than validating one.

**Bullets replicate as spawn events, not state.** ~36 bytes once per bullet;
both sides run the identical integration. Only early deaths (a hit, or a wall)
need announcing. Pinned by `tests/integration/test_replica_parity.gd`.

**No lag compensation.** Rewinding the world to a shooter's view would mean a
player who dodged on their own screen still takes the hit. If it becomes a
complaint, lag-compensate *player bullets against enemies only* — never enemy
bullets against players.

**`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. When it was not, drifting clocks landed in a dead zone where the
server silently rejected every input and the client never noticed. Pinned by
`tests/unit/test_input_lead.gd`.

---

## Combat feel

**Hitbox is smaller than the sprite** (`PLAYER_RADIUS` 6 vs
`PLAYER_VISUAL_RADIUS` 13), and `PLAYER_MUZZLE_OFFSET` derives from the visual
radius. A visible near-miss reads as fair; an invisible hit does not.

**No invulnerability frames.** Every bullet that touches you lands. I-frames
make dense patterns *safer* than sparse ones, which inverts the genre. Measured
cost: ~13.6s stationary in the Warden's opening phase. `spawn_grace` on entering
a dungeon is the sole exception, and it is a transition, not a combat mechanic.

**No contact damage.** Every threat is a bullet you can see and dodge. The
Stalker carries a point-blank shotgun rather than damaging you by touch.
`tests/unit/test_content.gd` asserts every hostile enemy has an emitter.

---

## Leaving a run

**Escape is a 1-second channel that damage does not interrupt.** An
interruptible channel makes killing the process better than pressing the button.

**A disconnect runs the same channel.** The player stays in the world as
`linkdead`, still killable. All four exits (key, menu button, clean disconnect,
SIGKILL) converge on one server-side path keyed on the socket closing — there is
deliberately no "clean leave" message. `tools/smoke.sh` asserts both the hard
kill and the polite disconnect.

**Boss rooms do not lock.** *(User, this session.)* You can always walk out of a
boss fight, and the boss cannot follow. The consequence: fights cannot rely on
trapping the player, and disengaging is always available.

---

## World

**Tile grid, generated layout, hand-authored boss arenas.** *(User, this
session.)* A grid because collision, line of sight and interest management all
become array lookups; authored arenas because a generated boss room is a bad one
about as often as a good one.

**Hard fog.** *(User, this session.)* No remembered terrain — anything outside
current line of sight is not drawn, including ground already walked over.

**Dungeon size scales with depth.** *(User, this session.)* `--depth N` is a dev
flag; what raises depth in actual play is still open.

**Never send the map, or its seed.** *(User, this session — corrected an earlier
choice of mine.)* Sending `(seed, depth)` and regenerating client-side is far
cheaper on the wire and hands any modified client the entire floor plan. Tiles
stream per peer instead. The accepted trade, in the user's words: a cheater
seeing further than they should is tolerable; seeing the whole map is not.

Consequence to preserve: the client holds *real* geometry it cannot see, because
it predicts movement against walls and simulates bullets that die on them. So
hard fog is a rendering rule, not secrecy. The secrecy is in what the server
declines to send.

---

## Identity and persistence

**Steam-shaped auth abstraction.** *(User, this session.)* The goal is
eventually Steam, so build the shape Steamworks uses and keep it swappable:
client presents an opaque ticket, server validates it and gets a stable 64-bit
account id (SteamID64's stand-in). A local dev provider persists a generated id
in `user://`, so **no Steam account is needed now**.

Not integrating GodotSteam yet: it needs a running Steam client and an app ID,
which would break the "no Steam account" requirement. Swapping it in later
should be one provider class and no schema change.

---

## Progression

**XP from kills, bosses worth far more.** *(User, this session.)* A first full
dungeon should give a bit more than is needed for the first level-up.

**Permadeath.** Death marks a character inactive — never deleted, for archival
and troubleshooting — and the player picks another character or creates one.

---

## Characters and progression *(this session)*

**Level 1 is base health; each level adds 10.** So level 15 is
`PLAYER_MAX_HP + 14 * 10` = 240. Level is *derived* from lifetime experience
rather than stored alongside it, so the two can never disagree — a hand-edited
save cannot produce a level 12 character with a level 3's experience.

**The five-character cap counts LIVING characters only.** Retired ones stay in
the store forever but free their slot. Counting the dead would lock a player out
of their own account permanently after five deaths, which is not a punishment
anyone signed up for.

**Death unbinds the character entirely.** There is deliberately no "return to
the hub as the character who just died" — the run is over, so the peer is
removed from the instance and left at the roster screen. The one exception is a
linkdead player, which has nobody to show a roster to, so its body is left for
the escape channel to resolve as before.

**Experience is shared across the party, undivided.** Everyone alive in the
instance receives the full amount for a kill. Splitting it would make bringing a
friend cost you progress, which is the opposite of what the hub roster exists to
encourage.

**A level-up heals by the amount it added.** Gaining a level mid-fight should
feel like relief, not like the bar you were watching got further from full.

**The character store refuses to start rather than starting empty.** A corrupt
or unreadable save aborts the server. Loading empty would look like it worked
and then overwrite every character on the first level-up.

**Account ids are written as decimal strings in JSON.** They are 64-bit and JSON
numbers are doubles, which would silently round them.

**Character swapping is hub-only, enforced on the server.** Swapping inside a
dungeon would be an instant, uninterruptible exit from danger — strictly better
than the one-second escape channel, and it would make that channel pointless.
The menu greys the button out so the rule is visible, but the server refuses
regardless of what any client's UI allows.

**Health regenerates at 0.5% of MAXIMUM per second, with no out-of-combat
gate.** A percentage rather than a flat rate, so it does not become irrelevant
at level 15 — a capped character regains 1.2 hp/s against a level 1's 0.5, and
both take about 200 seconds to heal from nothing. No combat gate because at this
rate it cannot out-heal anything actually shooting at you, and a trickle that
never stops is easier to reason about than a timer players have to learn.