Typing `\alpha` in a Lean 4 buffer gives `α`; `\<>` gives `⟨⟩` with the
point between them. The abbreviation table is vendored from
vscode-lean4 and the expander is a typed-edit consumer registered on
the Stage 4a chain at priority 50, ahead of auto-pairing.
The ordering is load-bearing. 64 abbreviation keys contain a character
in the `lean4` pair set, so with pairing first, typing `\[` would
insert `[]` and corrupt the pending key to `\[]` before the second `[`
arrives — `\[[]]` becomes unreachable. The consumer therefore claims
every keystroke that EXTENDS a pending abbreviation, not only one that
completes an expansion; claiming only completions would hand each
intermediate `[` to pairing by a different route.
The vendored table is an ORDERED SEQUENCE, not a map. Upstream breaks
equal-length ties by source declaration order — 101 prefixes depend on
it, and `\f` resolves through `f<` rather than `f>` — which a
`pairs`-iterated Lua table cannot express. `scripts/regen-lean-abbrev`
takes a vscode-lean4 commit, emits the file with its provenance header,
and aborts on a duplicate key, invalid UTF-8, or a round-trip mismatch.
Undo is cross-peer-degraded on CRDT frontends and that is accepted and
named, not papered over (Q#LN21): `\alpha` arrives as six source-peer
optimistic inserts while the expansion is one daemon-peer replace.
`set_round_trip_input` would fix it and also makes `dispatch_idle`
report false, so RET would stop inserting a newline.
Round 9 corrects three approved acceptance criteria that the real table
contradicts, found by simulating the state machine over all 1,855
entries and re-reading upstream at the pinned commit rather than
re-reading the prose. `\to` is not eager — `top`, `to0` and `toa`
extend it. `\zzzz` expands to `ζzzz ` because `ze`, `zeta` and
`zsqrtd` exist; only `$ % , ; @ W` open no key at all. And `\alpha`'s
undo does not restore `\alpha ` because `alpha` IS eager, so the
terminator is a separate edit. Criteria 38, 41 and 42 now state both
paths, and the false halves are asserted too: they read as correct
until the table is consulted.
Three implementation traps worth the record. The generator's own
round-trip check was broken twice and failed closed both times:
`str.splitlines()` splits on U+2028, which 53 symbols contain, and
escaping through `chr(byte)` produced a latin-1-shaped string that the
UTF-8 write re-encoded. The first check compared in-memory strings and
agreed with itself; it now stages the file, re-reads the bytes from
disk, and renames into place only on a match. And the expansion SHRINKS
the buffer, so the point must be placed explicitly — pairing's
no-cursor-motion rule holds only for an insert AT the cursor, and
without this every self-insert after the first expansion is silently
rejected and the editor looks dead.
25 acceptance tests plus one `--lib` test for the optimistic CRDT
producer (45f), which is where the gate list's `--features crdt` run
reaches it; a crdt-gated integration test would be dark in CI and in
the gates both. Fifteen mutations bite, each failing its target. Three
of these tests were vacuous when first written and biting is what
found them: the abandonment test asserted text a surviving record
would also produce, the re-arm test used an example that never reaches
the re-arm branch, and both switch tests ran through
`find_or_open`'s fresh-load path rather than `buffer.after-switch`.
No protocol change (Q#LN14). Also reconciles the handoff and ledger
for Stage 4a (#179) and adds `lean.abbrev` to COHERENCE.md's
config-registry adoption census, now nine settings.
Co-Authored-By: Claude Opus 5 (1M context) <noreply@anthropic.com>
Claude-Session: https://claude.ai/code/session_011LFvC4FQtux4y32KuevZ7B
Levi Neuwirth