### concurrent trigger
$ LD_LIBRARY_PATH=/tmp/libxml-compat swift run banal publish --json --vault /tmp/banal-batch-001-vault &
$ LD_LIBRARY_PATH=/tmp/libxml-compat swift run banal publish --json --vault /tmp/banal-batch-001-vault &
$ wait

### observed command results
# Two simultaneous publish processes were started against the same temporary vault.
# Exit codes: A=1, B=1
# A stderr contained UniformTypeIdentifiers compilation error: true
# B stderr contained UniformTypeIdentifiers compilation error: true
# Both processes failed before the publish pipeline executed; neither produced JSON,
# compiler information, an artifact path, or a publish artifact directory.
# Artifact directories after completion: none

### source-backed filesystem evidence
// Sources/BANALPublisher/PublishModels.swift:38-41
artifactDirectory: vault.publishURL,
stagingDirectory: vault.metadataURL.appendingPathComponent("stage", isDirectory: true),

// Sources/BANALPublisher/BorisAdapter.swift:140-147
let staging = configuration.stagingDirectory
if fileManager.fileExists(atPath: staging.path) {
    try fileManager.removeItem(at: staging)
}
let content = staging.appendingPathComponent("content", isDirectory: true)
let layouts = staging.appendingPathComponent("layouts", isDirectory: true)
try fileManager.createDirectory(at: content, withIntermediateDirectories: true)

// Sources/BANALPublisher/SiteCompiler.swift:33-43 (builtin compiler)
let fileManager = FileManager.default
if fileManager.fileExists(atPath: artifactDirectory.path) {
    try fileManager.removeItem(at: artifactDirectory)
}
try fileManager.createDirectory(at: artifactDirectory, withIntermediateDirectories: true)

// Sources/BANALPublisher/SiteCompiler.swift:154-157 (Boris compiler)
if fileManager.fileExists(atPath: artifactDirectory.path) {
    try fileManager.removeItem(at: artifactDirectory)
}
try fileManager.copyItem(at: relativeDist, to: artifactDirectory)

### final result
# final result: BF-RACE-3 failed. The runtime concurrency check was blocked by the
# Linux Swift toolchain's missing UniformTypeIdentifiers module, so mixed output was
# not observed directly. Independently, every invocation receives the same mutable
# staging and artifact paths, and both compiler paths perform unsynchronized delete/
# recreate or copy operations; overlapping publishes can therefore remove or replace
# another invocation's files and produce incomplete or mixed results.