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* lsp backend: ZLS as an in-process libraryGabriel Schneider2026-08-01
| | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | The seam's `query` now calls ZLS's analyser directly, on the worker thread, in this process. There is no zls binary, no subprocess, no JSON-RPC, no `initialize` handshake and no `Server` — `gd` is a function call whose answer comes back as rows. ZLS's build.zig already publishes its guts as an importable module (`b.modules.put("zls", ...)`), so this is a path dependency on the local 0.16.x checkout plus one new file, `src/lsp_zls.zig`. Construction is ZLS's own (tests/analysis_check.zig does exactly this): InternPool.init -> DiagnosticsCollection -> DocumentStore struct literal -> Analyser.init. `zig_exe_path` is null on purpose — shelling out to the compiler is the thing this backend exists to avoid — and `zig_lib_dir` is baked in from `b.graph.zig_lib_directory`, so `gd` on `std.mem.count` opens the same mem.zig the compiler used, with ZIG_LIB_DIR overriding at runtime. Offsets are `.@"utf-8"`, not ZLS's utf-16 default: `+Search` rows are byte columns and we are not on a wire. Seventeen probes, seventeen answering, no false claims, 5.9 MiB peak RSS. The features that were already Server-free are calls (hover, document symbols, code actions); the ones welded to `*Server` are reimplemented thin on top of public primitives — goto is gotoHandler minus the protocol, diagnostics is the in-process `std.zig.AstGen` branch of getAstCheckDiagnostics, references is symbolReferences' algorithm from the outside (offer every same-named identifier token back to the analyser and keep the ones that resolve to the same decl, so a shadowed local is not a false hit). What it does not do, deliberately: - Nothing is cached between queries. Each `query` builds a DocumentStore, resolves imports and throws it away, because the arena dies on return and `req.source` is a snapshot of a buffer the user is still typing into. So cold IS warm — there is no index to warm up. It is also fast enough not to need one: 124us for a local goto, 2.8ms into the stdlib, 8ms for references over a 5000-line file. A cross-query cache is a real design (a global, a mutex, an invalidation story), not a line of code, and it is the obvious next step rather than something smuggled in here. - References, rename and select-refs are THIS FILE only. Workspace-wide means loading every project file into the store and running the analyser over each; DocumentStore's own workspace iteration has the same limit (it can only see handles already loaded). Workspace symbols and workspace diagnostics DO walk the tree, because neither needs the analyser — a parse and a tree walk each. - Rename previews, format reports, code actions list. The seam hands back rows, not edits, so there is no channel through which a backend could rewrite the buffer. These answer the question the keypress asks and change nothing. - Without a zig binary, `@import("builtin")`, `@import("<pkg>")` and `@cImport` resolve to nothing — silently, which is ZLS's behaviour, not a bug introduced here. Relative imports and `std` work. - Non-.zig files answer nothing. The core does not gate the keymap by file type, so the gate is here: `gd` in a README must find nothing rather than parse prose as Zig and confidently resolve a word out of it. A whole-file report that ran and found nothing says so ("no diagnostics", "already formatted", "no code actions") rather than returning zero rows, because in this seam zero rows already means "no backend" — `lspResponse` opens nothing for an empty answer, so silence cannot also mean "checked, clean". Location queries keep the opposite rule: unresolvable is no rows. test/snapshots/lsp.snap covers the round trip end to end — gd jumping on a single result, SPC k opening +Hover, SPC s opening the +Search list that n steps, and gd on a keyword answering nothing without opening anything. The whole backend was also fuzzed at 20k queries over real, truncated and byte-smashed sources across every kind; that found two crashes (a decl's name token indexes its own file, not the requesting one, and is not necessarily an identifier at all on a half-typed line) which are fixed. emscripten does not get the backend: the web shell has no threads and no-ops the lsp effect, so it keeps the empty one the base tree shipped. DEPENDENCY: ZLS is FETCHED by the build system (build.zig.zon .url + .hash, pinned to commit 3e0d0820 on the 0.16.x branch) rather than a path dependency on the local genizah checkout, so it lands in zig-pkg/ like every other dependency and the build is reproducible from the .zon alone. Also passes -Dversion-string: ZLS's build.zig names itself by shelling out to `git describe`, and a fetched package is an extracted tarball with no .git, so every build printed a 'Failed to run git describe' warning. We pin the commit, so we already know the answer.
* LSP seam: async execution model, helix keymap, evaluation harnessGabriel Schneider2026-08-01
The base every language backend plugs into. Three parts: ASYNC. The core had no request/response shape - every effect was fire-and-forget or instantaneous. A language query is the first thing that answers later, so: Effect .lsp -> shell worker -> Event .lsp_resp. tty.zig uses io.concurrent + the vaxis queue, gui.zig a detached thread + the mutex queue it already had for ptys; web no-ops it. The worker never touches the core (path/source/arg are snapshotted into an LspJob), one query in flight identified by a monotonic id so a second press makes the first answer stale, and no rows is a legal answer. KEYMAP. Helix's, verified against its default.rs rather than recalled. gd/gD/gy/gi/gr and ]d/[d had no conflicts. The SPC letters did, so pardes's own builtins moved instead of helix's: Kill k->q, Del d->wc (closing a pane is a window op, and c is helix's own close), Dump/Restore s?->f?, Tutor ht->T. A three-exception muscle-memory map is not a map. RESULTS ARE +SEARCH ROWS. path:LINE:COL text, absolute. That is what look.zig resolves and n/N step, so one row from a goto jumps and several open a buffer - helix's multi-result picker needed no picker code. Backends supply exactly one function (lsp.query) plus a supports set and a name; the base has none on purpose. zig build lspbench scores them on the same corpus: feature matrix (trusting results, not the supports flag - a claimed-but-empty kind is reported as a false claim), cold and warm latency, peak RSS. Two snapshot scripts moved. leader.snap encoded the old key paths. chordcut.snap's last two steps clicked column 5, which lands on a FILE pane, so 'key c-b' toggled nothing and the typed text was being read as normal-mode keys - the golden recorded no TTY pane and no cat -v output anywhere. Pointing them at an actual shell makes both steps assert what their comments claim, and the tty paste chord is now covered for the first time.