Implements docs/lsp-file-watch-d3-framing.md revision 4, approved
2026-08-11 with the four rulings adopted as proposed: the honest bar
(absent at idle, one attributable job per concurrently due group), no
exclusions by default, server root_uri -> cwd -> attachment fallback,
and constants rather than config keys.
pmacs.fs.walk_tree: the whole recursive tree as ONE cancellable job
(JobKind::FsWalkTree, reply reuses ReplyKind::ReadDir --- identical
payload shape, so the Lua boundary needs no second conversion). Names
are base-relative; symlinks recorded, never traversed; an unreadable
subdirectory skips its subtree (scan_tree's pcall behaviour); only the
root failing to open fails the walk; the cancel token is polled once
per directory. Eight Rust unit tests, including flat-directory entry
parity with read_dir_blocking and the two review-round cancellation
cases (empty-tree pre-cancel; mid-walk via the cfg(test) entry hook).
The watcher itself is rewritten as the framed group scheduler. No
sleeps anywhere: one process.after-tick subscription (installed once
and guarded --- pmacs.hook.remove does not exist) drives every
(server, base) group's deadline off monotonic_ms, autosave's Q#AS2
idiom. The old design held one pool thread per sleeping watcher and
allocated 1 sleep + D read_dir jobs per watcher per tick --- 1,326
per tick for rust-analyzer's six watchers on this 220-directory
checkout. At idle there is now NO running job, which is also the
strongest witness in the suite: activity_summary settles to None, and
that assertion is unwritable under the old design.
The scheduler is the framing's state machine, all three review rounds
included: single-flight per group with generation-checked completions;
deadlines advanced from completion; the round-3 three-arm completion
partition (success / stale-or-retired / live non-success, with the
failure latch and quiet cancellation); joins wake the group, queue
exactly one follow-up mid-walk, and never reset the backoff curve;
per-watcher baselines --- the first snapshot whose WALK STARTED after
the join; membership captured at scan start; per-member cancellation
recheck at emit through the preserved _after_scan_for_tests seam;
backoff 250ms x2 to a 4s cap, reset by any emitted change; retirement
cancels the in-flight walk cooperatively.
Verification: eighteen acceptance tests. The six #234 tests are
byte-unchanged and green. Ten witnesses cover the framing's plan (the
review rounds added the fallback-determinism and root-boundary pair,
making twelve):
idle absence (and never a sleep purpose), one walk job per scan on a
twelve-directory fixture, join-wakes plus the registration epoch,
queued baseline for a mid-walk join (driven by saturating the worker
pool so the walk genuinely queues), single-flight under a withheld
completion pump, retirement and rebaseline through the fake's
unregister/re-register triggers, live cancel via pmacs._async._cancel
on the queued job, live failure with the once-per-error latch and the
preserved-snapshot recovery (DELETED for the pre-failure file is only
derivable from the retained snapshot), backoff shape from seam
timestamps, and the configured-root base.
Every witness was mutation-tested. Two findings from the bites:
- Retirement is DOUBLE-ENFORCED (unregister path and post-scan sweep)
and biting either copy alone is masked by the other; only biting
both goes red. Kept deliberately: the sweep covers seam-cancelled
members, the unregister path covers idle groups whose next deadline
is seconds away.
- The first idle probe was VACUOUS: it read pmacs.async instead of
pmacs._async, errored, and the unwrap_or_default made every sample
read as "absent". The probe now expects rather than defaults, so a
broken probe is a red test, not a green lie.
One environmental fact, recorded in the lane: an empty stray /tmp/.git
(since removed) made project detection root every markerless tempdir
fixture at /tmp, which under Q#D3-3 the watcher then faithfully
watched. A markerless-fixture red that looks like a watcher bug may be
an ancestor marker.
A pre-commit review round found four blockers, all fixed here:
- walk_tree checked cancellation only inside its entry loops, which an
EMPTY tree never enters --- a pre-cancelled queued walk returned an
empty SUCCESS, which the success arm would commit and diff into a
deletion storm. Cancellation is now checked before opening and
before returning, cancellation outranks a missing-root error, and a
unit test pins both.
- The neither-root-nor-cwd attachment fallback was still pairs-order
nondeterministic --- the exact accident D3 set out to remove, behind
a comment claiming otherwise. It now takes the lexicographically
smallest attachment directory. Verified at the spawn sites: every
server spawned with an attached file gets cwd = root, so the arm is
defensive and unreachable through production spawning --- which is
also why it carries no through-the-server witness.
- A base at the filesystem root joined as //path (and file:////path in
URIs). Both join sites now go through join_under, the root-aware
idiom dired's handler already uses, and the dir-of capture for a
root-level file ("" from the match) normalizes to "/".
- The walk-count and scan-times probes defaulted on error, so two
broken probes could compare equal and pass the retirement witness.
Every probe now expects --- a broken probe is a red test, the same
correction the vacuous idle probe forced.
A second pre-commit round found three more, all fixed here:
- Mid-walk cancellation was UNWITNESSED: both Rust cancel tests
pre-cancelled and the acceptance test cancelled a queued walk, so
deleting the internal polls left every test green. A cfg(test)
entry hook now flips the token at an exact entry boundary and the
witness asserts the walk stopped NEAR it (bound on entries
processed), which is what discriminates the polls from the
entry/exit checks. The retirement witness now holds a walk in
flight across the unregister and asserts the job settles cancelled.
- The "unreachable fallback" claim was WRONG: pmacs.lsp.spawn may
omit both cwd and root_uri, and ensure_server adopts such a live
server for markerless files (root_uri and key_uri both nil). The
lexicographic-minimum fallback now has a through-the-server
witness: five sibling directories, the minimum opened last ---
five, because with two the build's hash order coincided with the
lexicographic answer and the first-pairs bite survived.
- The root-boundary joins gained a witness through exported
production functions (the _deliver_status pattern): the matcher and
URI builder driven at base "/", where reverting either join_under
call makes the anchored glob refuse //hit and the URI grow a fourth
slash. No fixture can walk / for real.
Verification totals after both rounds: eight walk_tree unit tests,
eighteen acceptance tests (six byte-unchanged, twelve witnesses), all
mutation-verified.
No wire change, no PROTOCOL_VERSION bump; walk_tree is an fs binding.
Co-Authored-By: Claude Fable 5 <noreply@anthropic.com>
Levi Neuwirth
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