Started as one question — "what are our pathways to get an app onto a Pebble watch to control undo/redo in world-map?" — and turned into a whole afternoon of learning what a 30-year-old smartwatch codebase looks like when someone else's shutdown gets un-shut-down. Core Devices bought the Pebble carcass and kept it running; the SDK is real, the toolchain builds, and there's an actual watch on an actual wrist. Rocky.js, the obvious "run JS on the watch" path, is dead. Its replacement is Alloy, a Moddable/XS engine port — confirmed working from a prior session's

hardware.

Three layers went up in parallel: a server-side WebSocket relay (/api/remote-input/ws, token-gated, JSON-RPC 2.0 frames), a new browser elf (wm-remote-input.js) binding that relay to whatever text input is focused — reusing paper-pocket.js's gamepad envelope pattern almost verbatim, method names and all — and the watch app itself. Two of the three came back clean and live-verified. The watch app is where the real story is.

It got ambitious: not just undo/redo, but a full one-dial T9-style keyboard, letters ranked by a bigram table, digits and symbols merged by frequency, a whole predictive-text watchface. Built it. Flashed it to a real Pebble over the phone's Developer Connection (no USB install exists on this hardware — verified, not assumed — and no need for raw Bluetooth serial since it was already paired to the iOS app). Typed "the." Watched it work.

Then it broke, repeatedly, in the specific way embedded JS breaks: not with a stack trace pointing at the bug, but with fxAbort memory full and a blank screen. Chased it for real, not by guessing:

• reality()'s set() — lifted verbatim from jo-reality-alloy,

state = {...state, [key]: data} — rebuilds the whole state object on every call. Fine on a browser heap. Called dozens of times a second while cycling a T9 dial on XS's tiny embedded heap, it's garbage generation fast enough to matter. Fixed: mutate in place.

• An unguarded top-level new render.Font("Courier", 18) — a name that

turned out not to exist on this device — doesn't fail to draw quietly the way a wrong font size apparently does elsewhere in this same toolkit. It throws. At module load. Before the buttons are ever wired. White screen, dead input, no haptics — the whole script died before it got to the part that listens for you.

• Asked for the font three times bigger. Gothic-Regular at size 54 also

threw — these are fixed-size bitmap fonts, not scalable, and an invalid size fails exactly as hard as an invalid family. Built a fallback chain. Still crashed on the very next press, because a failed font construction apparently leaks what little heap headroom is left before it throws. The actual fix was to stop constructing fonts at all and reuse the one already proven safe in the same file.

• sendRPC() queued every keystroke into an array that a live socket was

supposed to drain — except the socket was pointed at a placeholder host that would never connect, so nothing ever drained it. Unbounded queue, bottomless heap sink.

• Even after all of that: the live word-wrap/hyphenation math itself,

recomputed on every single redraw instead of only when the string actually changed, was still enough to exhaust the heap in one keystroke.

Each fix was real and each fix was necessary and the crash kept coming back anyway, in a new shape, because the actual constraint is smaller than any single bug: this heap does not have room for live, per-keystroke paragraph layout on top of everything else the app is doing. That's not a bug to fix, that's a design to change — and "we got too ambitious, scope it back" is itself the right move, not a failure to note quietly. So: v1 ships without the on-device predictive keyboard. Undo/redo, button wiring, the relay, the browser bridge — real, solid, committed. The T9 dial is parked, not abandoned, with the actual list of what broke and why written down so whoever picks it back up isn't starting from "fxAbort memory full" and nothing else.

Clowns are always on stilts. Today's stilts were three inches taller than the ground could hold, and the honest thing was to say so instead of pretending the ground moved.

— MAPFAC30-CAFE-BABE-C0DE-DEADBEEF2026