improvise-2oxt. All four casts under docs/casts/ opened and closed on
`(0) Mac:<hostname> ~gf/u/edwlan/improvise` — a real hostname and home directory
on what improvise-kh8 made the site root — and `formulas.cast` and `import.cast`
showed that prompt as their visible OPENING frame. drill.cast also predated the
records columns entirely, showing a single `Value` column where the current
build draws a column per measure plus `+cat` and `+`.
The repair is structural, not careful. `docs/record-casts.py` drives `improvise`
on a pty it owns and writes asciicast v2 itself, so `improvise` is the pty's ONLY
child and there is no shell for a prompt to leak from — nothing to remember to
clean, and nothing that comes back when somebody re-records on another machine.
Three other things stopped being accidents with it: the geometry is an input
(120x37, the numbers docs/index.html already spelled, so they did not change),
the pacing is a per-step table, and the header carries no `env` (which held
$SHELL) and no `timestamp` (the recording machine's clock).
Two decisions that each cost a re-record. No `:q` is typed at the end: the player
loops, so the last frame is also the frame before the first, and a minibuffer
reading `:q` is what it would show — the process is signalled instead. And each
scenario had to be ARRANGED so the thing it names is visible: the drill cast
drilled into a cell with no records behind it, and the pivot cast pressed `c` on
a category already on the column axis. Both recorded cleanly and demonstrated
nothing — true frames about the wrong thing — and neither was visible from the
keystroke list.
That is the method worth keeping: a cast can be replayed through a small ANSI
reconstruction and READ AS TEXT, so "what does frame N show" has an answer rather
than a guess. It is how the `+cat`/`+` columns in the new drill.cast were
confirmed present, and how both dud scenarios were caught.
The guard is `landing.spec.js`, asserted over the cast FILES: no header carries
`env` or `timestamp`, the geometry is the one the page configures, and no chunk
contains an OSC window-title sequence — the leak's signature, emitted by a shell
once per prompt with the cwd in it and by `improvise` never. Asserted over the
file rather than the rendering because a player draws a prompt as ordinary text,
so a screenshot assertion would have to know what the hostname had been. BOTH
clauses were injected separately, because the `env` one would otherwise mask the
OSC one: the old cast fails on `env`, and the old cast with `env` stripped fails
on the title sequence.
docs/index.html loses the `p.dated` note admitting the drill cast was out of
date, which is now false.
Tests: 33 harness + 3 skipped (was 28 + 3). Rust and node unchanged.
Co-Authored-By: Claude Opus 5 (1M context) <noreply@anthropic.com>
Claude-Session: https://claude.ai/code/session_01FC2jVn8Au7E9JPkw6bwXXH
Edward Langley