gotreesitter v0.55.0

Added

• Add WithHighlighterAdmissionCandidateRoute to select the route for the
  document parser and injected parsers (#1281).
• Add optional compact parser telemetry for peak frontier headers and derivations
  (#1285).
  Locked C checks cover three fresh JSON trees and seven fresh CSV witnesses.
  One incremental edit per language also matches with subtree reuse.

Changed

• Give explicit process settings priority over the language admission allowlist.
  A parser override still has first priority. The allowlist now widens only
  the implicit default. This behavior change requires a minor release.
  Both SetAdmissionCandidateRouteDefault(false) and
  GTS_ADMISSION_CANDIDATE=0 keep production selected
  (#1281).

Fixed

• Ignore Accept when the compact reduction collector checks whether a source can shift
  (#1284).
  Four strict Scala witnesses match locked C without compact fallback.
• Elect accepted material paths inside the winning compact recovery group
  (#1286).
  Preserve acceptance identity across grammar forks and closed error regions.
  Decline unsupported paths without publishing a guessed tree. The PHP compact request still falls back before acceptance.
• Bound end-of-file (EOF) recovery versions before allocating reduction parents
  (#1287).
  Apply the native symbol-zero trial only to the certified Scala grammar blob.
  The Scala suffix suite records 50 exact matches and seven unchanged gaps across 57 cases.
  The 104,681-byte Swift witness completes without truncation or a memory stop.
• Prevent overlapping Python escape_sequence nodes when escaped backslashes
  precede a newline. All 18 fixtures now match the locked C tree on both routes;
  12 matched before the fix. Fixes #1275
  (#1276).
• Preserve Python list_splat binding for attribute and subscript suffixes
  during mixed flat and graph stack merges. Seven C fixtures match on both routes.
  Exact C tree differences across 2,932 Django files fell from 101 to 6.
  Fixes #1274
  (#1277).
• Reject query runs that cannot reach a required successor before enumerating
  capture combinations. Preserve highlight capture order for identical spans
  and prefer a highlight over @spell. Report quantified roots as non-rooted
  in IsPatternRooted (#1278).
  The production query on 755 Nushell comments fell from 16,577.358 to 0.360 ms.
  Full highlighting of that 8 KB file took 20.132 ms after the change.
• Cache raw-shape error costs during generalized left-to-right (GLR) elections.
  Bound graph reachability checks and reject impossible merges earlier
  (#1279).
  The reporter's C# fixture changed from quadratic growth to approximately linear growth.
  Production parsing at 32 KB fell from 12,662 to 900 ms.
  A separate 137 KB run measured a 3,008 ms median after the final merge precheck.
• Stop Make forest rescue at the first dead end when it cannot accept recovery.
  A reconstructed 3.5 KB fixture with an early error fell from 27,377.173 to
  13.015 ms on production (#1282).
• Build C-certified HTTP sections directly for newline-terminated, nonblank
  # comments under the certified grammar hash. Preserve deadlines and
  memory budgets; disable incremental reuse for these direct trees
  (#1282).
  Production parsing at 32 KB fell from 2,160.112 to 1.657 ms.
  The result now matches the complete C tree instead of returning one error node.
  Maximum resident memory fell from 2,178,624 to 12,892 KiB.
• Stop incremental reuse with low yield after bounded work and retry a fresh parse.
  The guard requires an early edit, a live graph fork, and at most four root children.
  The guard applies across grammars (#1282).
  Production insertion in the reconstructed 137 KB Dart fixture fell from
  258.646 to 119.063 ms. Maximum resident memory fell from 220,912 to 123,796 KiB.

Measurement scope

These measurements come from the linked pull requests on Linux amd64.
They do not establish Windows performance. C# runs used the reporter's exact
fixture; Make, HTTP, and Dart used deterministic reconstructions.
Host load varied during the C# sweeps. The Nushell baseline used one repetition;
the result after the change used the median of three repetitions.

PR #1282 completed the standard Go trio with 20 shuffle seeds and 750 ms per benchmark.
It used one process per seed, GOMAXPROCS=1, and GOWORK=off.
The benchmark comparison found no significant time change:

Benchmark	Before ns/op	After ns/op	B/op, unchanged	allocs/op, unchanged
Full parse	3,456,000	3,411,000	1.224 KiB	8
Single-byte edit	91,310	90,720	386	5
No edit	3.307	3.294	0	0

The linked pull requests contain reproduction commands and separate correctness evidence.

PRs #1284–#1287 each record 20-seed randomized comparisons without significant changes in the three primary parse times.
PR #1285 shared its host with another workload; its timing evidence has that limit.
PR #1286 measured 111,092 KiB maximum resident memory for a 512 KiB Go parse.
PR #1287 measured warm Swift maximum resident memory of 257,440 KiB before and 257,332 KiB after the change.
Its primary allocation counts remained 8, 5, and 0.

Publication exception

On 2026-09-24, the owner approved a one-time tag-creation exception for v0.55.0.
The exception permits publication without a workflow-only tag-creation actor rule.
All other gates remain mandatory under the release process.

Known gaps

• #1280 remains open and is excluded.
  Transient-error incremental trees and the diff and LESS edit mismatches remain unresolved.
  Its locked C gate still fails for malformed JavaScript, LESS, and TOML fixtures.
• C# still takes about three seconds at 137 KB on the measured host.
  Graph stack merges remain under investigation; the sub-second target remains open.
• Scala remains unresolved. A Linux bisect identifies grammar update 74159ec1b
  as the fresh-parse regression trigger. Linux edits did not reproduce the
  Windows slowdown. Preserve the new grammar's coverage while investigating its cost.
• Blank HTTP # comments retain the existing parser route and need a locked C regression.
• Six Django files retain separate C tree differences after the Python splat fix.
• CSV , and a,b, still differ from locked C on both parser routes.
• The PHP compact recovery winner remains open; the generated corpus records 6 of 25 exact deep matches.
• Seven Scala suffix gaps predate the EOF recovery bound. Other grammar blobs retain the exact EOF row.