API server reports TS2345 for a call that tsc accepts on the same project

[vivere-dally]

Repro: https://github.com/vivere-dally/tsgo-api-ts2345-repro

@typescript/native (typescript) 7.0.2, darwin-arm64, node v24.21.0, macOS 26.5.1. The project uses sigma 3.0.3 and @sigma/utils 3.0.0. strict is not set.

Steps

1. npm install
2. npm run probe. The script starts 25 fresh node processes. Each process makes one new API({ cwd }) of @typescript/native/unstable/sync, calls updateSnapshot once, and reads program.getSemanticDiagnostics() once.
3. npm run batch. The script runs tsc -p tsconfig.app.json 25 times.

Expected

The server and tsc give the same diagnostics for the same project and options.

Actual

• tsc: 0 of 25 runs report an error. Classic typescript 6.0.3 also reports no error.
• The server: 25 of 25 processes report TS2345. An earlier run gave 209 of 210.

error TS2345: Argument of type 'GraphRenderer' is not assignable to parameter of
type 'Sigma<Attributes, Attributes, Attributes>'.
  The types returned by 'getSettings()' are incompatible between these types.

The call is fitViewportToNodes(renderer, []) in src/widgets/graph-canvas/canvas-setup.ts.

Observations

• One process gives the same answer in five queries. Thus the difference comes from program or checker construction.
• The project needs both source files. With the caller merged into canvas-setup.ts, 0 of 20 processes report the error.
• Without the typed constant emptyDrawer, tsc also reports TS2345. With the constant, tsc accepts the call, and the server does not.
• In the full application that this comes from, about one server process in four reports the error.

The server result seems to depend on the order of type checks. I do not know which of the two answers is correct.