Simplify MphfLayer::open by removing explicit IndexMode parameter

The MphfLayer::open signature now accepts only a directory path. Mode configuration is resolved internally via disk-based auto-detection using LayerEvidence, eliminating the need for explicit arguments from callers. All internal query methods and external call sites have been updated accordingly, while TypedLayer::open temporarily retains the unused parameter for future cleanup.

src/obikphylo/src/siblings/build.rs

@@ -6,7 +6,6 @@ use rayon::prelude::*;
 
 use obikseq::CanonicalKmer;
 use obikindex::layer::MphfLayer;
-use obikindex::layer::meta::IndexMode;
 use obipipeline::ThrottleGuard;
 use obisys::progress_bar;
 
@@ -98,7 +97,6 @@ impl SiblingAnnexBuildExt for KmerIndex {
                 part_slots += build_layer_sibling_annex(
                     self,
                     &self.layer_dir(part, l),
-                    &meta.mode,
                     n_parts,
                     l,
                     &cache,
@@ -123,12 +121,11 @@ impl SiblingAnnexBuildExt for KmerIndex {
 fn build_layer_sibling_annex(
     index: &KmerIndex,
     layer_dir: &Path,
-    mode: &IndexMode,
     n_parts: usize,
     l: usize,
     cache: &Arc<PartitionCache>,
 ) -> OKIResult<u64> {
-    let mphf = MphfLayer::open(layer_dir, mode).map_err(olm_to_ok)?;
+    let mphf = MphfLayer::open(layer_dir).map_err(olm_to_ok)?;
     let k = index.kmer_size();
     let n = mphf.n();
 

src/obikphylo/src/siblings/tests.rs

@@ -99,7 +99,7 @@ fn annex_info_for(idx: &KmerIndex, kmer: CanonicalKmer) -> FamilyMask {
     let meta = idx.partition_meta(0).unwrap();
     for l in 0..meta.n_layers {
         let layer_dir = idx.layer_dir(0, l);
-        let mphf = MphfLayer::open(&layer_dir, &meta.mode).unwrap();
+        let mphf = MphfLayer::open(&layer_dir).unwrap();
         if let Some(slot) = mphf.find(kmer) {
             let annex = SiblingAnnex::open(&layer_dir.join(ANNEX_FILE_NAME)).unwrap();
             return annex.get(slot).expect("slot must have a computed annex entry");