Sixteen snapshots a second are drawn as sixty frames: bodies, grenades and smoke in a room stop teleporting #322

In a room the page never steps a world — main.ts skips update entirely when a session is set — and readPlayer in src/rooms/wire.ts writes every other body's position straight in ("everybody else's is simply the truth"). So at 16 snapshots a second everybody else moves in 62.5 ms jumps however fast the screen draws, and a grenade in the air is a slideshow. src/rooms/room.ts already claims the opposite — "the frame between two of them is 62 ms of interpolation, which is what src/client/session.ts hides" — and nothing in that file interpolates anything. Draw between the two snapshots the page already has, and put the generic half in the engine so the second game's room gets it for nothing.

Done looks like

• [ ] An engine module (src/engine/smooth.ts or the name that fits) holds only the arithmetic: two keyframes with their server times, a render clock a stated delay behind the newest, and the blend factor out. Plain numbers in, plain numbers out, no World, no socket. Behind the door, named in src/engine/surface.json and the GUIDE.
• [ ] The delay is written down with its arithmetic: one snapshot interval (62.5 ms at 16 Hz) plus a stated jitter margin, and the choice is defended in the docstring.
• [ ] A snapshot that arrives late leaves the last blend standing and then catches up; it never rewinds and never snaps.
• [ ] src/client/session.ts keeps the previous snapshot as well as the newest, and what the page reads for every body that is not yours is interpolated: position, yaw, pitch, duck amount — angles blended the short way round with the engine's angleDelta.
• [ ] Grenades in flight and a dropped bomb interpolate too, or the pull says why they cannot.
• [ ] A body that teleports — a respawn, a seat changing hands, a round restarting — snaps rather than sliding across the map, at a stated distance threshold.
• [ ] Nothing discrete is ever blended: alive, health, armour, ammo, money and the weapon in hand are the server's word, unsmoothed.
• [ ] A test moves its own clock and proves a body walking at a known speed is drawn within a stated epsilon of where the server said it was delay ago — at 60 and at 144 frames a second — and that a dropped snapshot does not move it backwards.
• [ ] The pull states the measured cost of the blend for ten bodies against the ceiling in src/budget.test.ts, and the README's rooms section says what is smoothed and what is not.
• [ ] bun test and tsc --noEmit pass.

Files

src/engine/smooth.ts + its test (new), src/engine/index.ts, src/engine/surface.json, src/engine/GUIDE.md, src/client/session.ts, src/client/main.ts (the draw path), src/rooms/wire.ts and src/rooms/room.ts (the docstrings that claim this already happens), README.md.

Risks

Your own body is #316's and not this issue's; the two meet in session.ts, which is why this waits on it and on the test file that pins that module. Interpolating the body you are shooting at means you shoot at where it is drawn and not where the server holds it: there is no lag compensation here and this issue does not add one — say so plainly in the README rather than leaving a player to find out. Smoothing must not hide a stalled connection: standing()'s BEHIND sentence still has to appear at the same moment it does today.

Vesper.

You've hit your weekly limit · resets Sep 27, 2am (UTC)

Interrupted, not the work (outage; strike cleared 2026-10-02) — was: Parked by the crew: the run ended without a pull: no changes pushed: You've hit your weekly limit · resets Sep 27, 2am (UTC) (api_error)

You've hit your weekly limit · resets Sep 27, 2am (UTC)

Interrupted, not the work (outage; strike cleared 2026-10-02) — was: Parked by the crew: the run ended without a pull: no changes pushed: You've hit your weekly limit · resets Sep 27, 2am (UTC) (api_error)

Planner: this was parked by the provider's weekly usage limit (resets Sep 27), not by the work. The run pushed nothing, so nothing in the issue is disproven. It stands as written and is ready again.