Make tsCodegenSampleCheck actually able to fail

[kubukoz]

tsCodegenSampleCheck is the CI gate meant to fail when typecheck/src/generated.ts is out of date. It could never fail: before was read in the task body, but sbt evaluates the sampleCodegenRun.value dependency before any of the body runs — so codegen had already rewritten the file by the time before was read, and before == after always held. Worse, running the check destroyed the stale content instead of reporting it, leaving git status clean.

Fix

Parameterise the codegen run on its output path so the check generates into a temp file and compares, leaving the committed sample untouched:

def sampleCodegenRunTo(out: File) = Def.taskDyn { ... }

tsCodegenSampleCheck := Def.taskDyn {
  val out = tsCodegenSampleFile.value
  val tmp = IO.createTemporaryDirectory / "generated.ts"
  sampleCodegenRunTo(tmp).map { _ =>
    if (!out.exists || IO.read(out) != IO.read(tmp)) sys.error(...)
  }
}.value

tsCodegenSample keeps writing to tsCodegenSampleFile. The now-unused sampleCodegenRun key is removed.

Verification

Reproduced by deleting one real export from the committed sample:

	before	after
stale sample	[success]	[error] … is out of date — run sbt tsCodegenSample and commit the result
git status after check	clean (overwritten)	still M (untouched)

Also confirmed the check passes on an up-to-date sample, and that sbt tsCodegenSample regenerates byte-identically to what is committed — so the sample on main is genuinely current.

Note

sbt cannot load this build inside a git worktree at all: sbt-git's bundled JGit throws NoWorkTreeException: Bare Repository has neither a working tree, nor an index on the .git file worktrees use. Pre-existing and unrelated to this change (a dependencyOverrides JGit bump does not help — sbt-git resolves it on the meta-build classpath). Verification was therefore done against a plain clone. Possibly worth its own issue.

Fixes #22

🤖 Generated with Claude Code