Framing Q#LN7, Q#LN8, Q#LN16; acceptance 22–28, 24a/24b, 35, 36, 36a, 37.
Stacked on Stage 3a (#167), whose notification/response seams and
`pmacs.fs.canonicalize` this consumes. No protocol change; the only Rust
outside the test helper is one `include_str!` line.
**The Lake-aware root (Q#LN8).** `pmacs.project.detect` cannot express
this rule — it is innermost-wins by construction, and a Lake package's
`lean-toolchain` sits at the outermost level, so a file under
`<pkg>/.lake/packages/dep/` belongs to `<pkg>`'s server rather than
`dep`'s. The resolver walks up collecting markers and returns the
outermost, stopping at `pmacs.project.search_boundary()` so a stray
marker above a fixture cannot leak in.
Two things about the marker test are easy to get wrong in opposite
directions, and both are pinned. `io.open` **succeeds on a directory**,
so a truthiness check accepts a `lean-toolchain` directory; but
requiring a non-nil read rejects an **empty** `lean-toolchain`, which is
a legitimate marker — `locate-dominating-file` semantics are existence,
not content. The discriminator is `read`'s second return: decline only
on a non-nil error. Acceptance 24a and 24b each fail against the
implementation that satisfies only the other; both bites are recorded.
The root is canonicalized once up front, because a configured root
reaches `file_uri_for` verbatim and that URI is the affinity key (#161).
Canonicalizing the starting directory suffices — every ancestor of a
canonical path is canonical, since the walk only strips components.
**`lake serve` with a lazy probe and a one-shot latch (Q#LN7).** Nothing
runs at init: `pmacs.lsp.config` is declarative, and spawning a process
at startup for every user, Lean-using or not, is the cost rev 1 refused.
Both the probe and the server spawn are gated on a real Lean attachment.
The probe cannot gate the first attach — there is no blocking process
run, so its verdict arrives after `ensure_server` has already decided.
Hence the optimistic spawn, with the probe and latch correcting it. A
non-zero probe exit is deliberately NOT a trigger: §2.9's elan-shim case
makes `lake --version` fail on machines where `lake serve` still works,
and the server-failure latch covers that better. The probe answers only
the question failure detection would answer slowly — an old-but-working
lake that starts a useless server.
The latch stops the failing server **before** spawning the fallback, and
that ordering is load-bearing rather than defensive: the spec default is
`OnCrash`, the termination handler never consults the exit code, and
`maybe_restart` has no attempt ceiling, so a broken `lake` respawns
forever underneath the latch. `pmacs.lsp.stop` sets `restart = Never`,
which is what disarms it. Bitten: removing the stop fails acceptance 36.
The swap rewrites `command` and `args` only, so a user's `env`,
`settings`, `init_options` and `root` survive — a wholesale table
replacement would discard their `init.lua` at the moment they are least
likely to notice.
**`waitForDiagnostics` (Q#LN16)** resolves through Stage 3a's response
seam, with `M-x lean.wait-for-diagnostics` on top. `$/lean/fileProgress`
subscribes on the notification seam and is pinned end-to-end through a
new `leanprogress` mode on the fake server rather than by calling the
handler directly — the wiring is the only part that can break.
**Attribution (COHERENCE §9/§1.2).** The probe spawns as
`lean:lake-version-probe`, so a user wondering why their editor touched
`lake` finds an owner in `pmacs.process.list`. The latch reports through
`pmacs.editor.set_status` — the channel that exists — and acceptance 36a
observes that channel, so a report made only through the undefined
`pmacs.error` would fail it.
**Stage 1's acceptance 12 is updated, half superseded.** It asserted
`pmacs.lsp.config.lean4 == nil` to guard against a Stage-3 front-run;
Stage 3b is that stage, so keeping it would pin the opposite of the
intended behavior. The half that survives is the one about restraint,
and it matters more now: constructing an editor spawns nothing even
though the config exists and names `lake`, and opening a Lean buffer
with no server configured spawns nothing either. That is what holds
Q#LN7's "not at init" promise.
Bites recorded, all against the committed tree: bare `io.open` -> 24a
fails, 24b passes; require-non-nil-read -> 24b fails, 24a passes; no
canonicalization -> the symlink case spawns two servers; no stop before
fallback -> acceptance 36 fails.
Levi Neuwirth
1e1be67b49