AIGuiders.Platform.Modeling.Language.Adapters.Fcs 0.1.0

AIGuiders.Platform.Modeling.Language.Adapters.Fcs

F# Compiler Service backend for the Language Resolver Center — F# diagnostics, outline, navigation, cross-project find-usages, completions and rename behind ILanguageBackend.

What you get

• FcsLanguageBackend — an ILanguageBackend over FSharpChecker (LanguageId = "fsharp", handles .fs / .fsx / .fsproj):
  • GetDiagnosticsAsync — parse + type-check diagnostics; .fsx resolves standalone from script options; .fs without a resolvable fsproj falls back to parse-only diagnostics
  • GetDocumentSymbolsAsync — parse-only outline: modules and nested modules (with children), let bindings, type definitions; container chains like App.Math.calculate
  • GoToDefinitionAsync / FindUsagesAsync — symbol-use based; find-usages spreads across the F# projects of the solution graph when bound, deduplicated by range + file
  • GetCompletionsAsync — declaration list after partial long names / .
  • GetSymbolAtPositionAsync — kind, name, and qualified name at cursor
  • RenameSymbolAsync — workspace rename as file writes: Apply = false returns the planned Changes, Apply = true writes via the patch applier; active patterns and active-pattern cases are rejected with a message
• Execution-bound seams (the modeling layer does no File IO — a host binds implementations at startup):
  • IFcsProjectOptionsSource + FcsProjectOptions (bindSource, tryGet, invalidate) — fsproj context for semantic checks
  • IFcsSourceTextSource + FcsSourceText, IFcsProjectOwnershipSource + FcsProjectOwnership (resolveFsproj), IFcsSolutionGraphSource + FcsSolutionGraph
  • IFcsSessionPatchApplier + FcsSessionPatchApply — disk-backed patch apply
• FcsSessionPatchBridge — pure mapping between rename edits and the Ide.Session SessionPatch (renameFileChangesToPatch, patchToRenameFileChanges, tryApplyPatch)
• FcsProbeWire + FcsProbeWireMapping.toFcsOptions — pure probe wire to FSharpProjectOptions, guarded by FcsProjectOptionsGuards.requireFrameworkReferences (rejects options missing System.Runtime)

Quick start

open System.Threading
open AIGuiders.Platform.Modeling.Language
open AIGuiders.Platform.Modeling.Language.Adapters.Fcs

let backend = FcsLanguageBackend() :> ILanguageBackend

// .fsx scripts resolve standalone — no host binding needed
let request : LanguageRequest =
    { FilePath = "script.fsx"
      Line = 1
      Column = 1
      SourceText = "let x = 1 + \"oops\""
      SolutionOrProjectPath = ""
      SessionDefaultLanguageId = LanguageIds.Fsharp }

let result = backend.GetDiagnosticsAsync(request, CancellationToken.None).Result

Problem

• You want F# language smarts outside an IDE — an agent tool, a review bot, a doc pipeline — and wiring FSharpChecker by hand means re-solving the same puzzles every time:
  • script (.fsx) vs project (.fsproj) options resolution
  • extracting symbol uses for go-to-definition and find-usages
  • a rename that touches multiple files without corrupting edits
• Doing it inline also drags disk and solution-graph IO into what should be a pure, testable core.

Solution

• One backend that owns the FCS mechanics and speaks the kernel envelopes; everything disk-shaped (options, source text, ownership, solution graph, patch apply) goes through bindable seams, so the adapter stays usable pure and the host binds real IO at startup.
• Renames are computed as per-file writes from deduplicated symbol uses, applied through the session-patch bridge.
• This is the F# slot of the federation Language Resolver Center, run by its CDP host — ADR-0061, on the solution/session SSOT of GUIDERS-FSHARP-ADR-0004.

When not to use

• This mirror speaks F# only — C#, TypeScript and friends need their own backends; the shared contract lives in AIGuiders.Platform.Modeling.Language.
• Expecting project-grade results without binding the host side: with no IFcsProjectOptionsSource/ownership bound, .fs files degrade to parse-only diagnostics and completions/find-usages/rename return empty (.fsx still resolves standalone).
• Renaming active patterns (and their cases) — rejected by design; and there is no formatting, no code fixes — the verb set is diagnostics, outline, navigation, usages, completions, rename.

Learn more

• ADR-0061 — Language Resolver Center
• GUIDERS-FSHARP-ADR-0004 — IDE Session modeling ownership

MIT · Source & issues · part of the Guiders federation