analysisNameFromFileStem

Once-at-default auto-fill helper for markSaved paths in configuration-shaped apps: derive a fresh analysis name from a just-saved file's stem, but only when the current analysisName is still at its default sentinel.

Pre-decomposition, Scenario / Experiment / Simopt each carried a near-identical 6-line block inside markSaved:

if (myOutputConfig.value.analysisName == "Untitled") {
    val stem = path.fileName.toString().substringBeforeLast('.')
    if (stem.isNotBlank()) {
        myOutputConfig.value =
            myOutputConfig.value.copy(analysisName = stem)
    }
}

Simopt additionally piped the stem through sanitizeAnalysisName. This helper captures the shared shape so each host's markSaved collapses to a single call. Returns the new name to apply, or null when no change is warranted — caller is responsible for the copy(analysisName = …) mutation.

Semantics:

• Returns null when currentName is not sentinel. Once the user has set a non-default name, save-as to a different file must NOT silently rename their analysis.

• Returns null when the file's stem (the name without the final .ext) is blank — happens for hidden files like .config or paths whose final segment has no characters before the dot.

• Otherwise returns sanitizer applied to the stem. The default sanitizer is the identity function, so Scenario / Experiment get the raw stem; Simopt passes sanitizeAnalysisName to coerce the stem into the same shape used elsewhere in the Simopt pipeline.

Parameters