docs: state generic recipe invariants

Author: HaoZeke

src/eb_parse.rs

@@ -1428,7 +1428,7 @@ pub fn candidate_matches_dep(c: &Candidate, dep: &ResolvedDep) -> bool {
 /// toolchain pin, only candidates whose toolchain is a member of `hierarchy`
 /// count (e.g. CapnProto on GCCcore-14.x does not satisfy foss-2026.1 which
 /// needs GCCcore-15.2.0). Explicit fourth-tuple pins still match exactly,
-/// including cross-generation residuals (`xtb`/gfbf-2024a).
+/// including explicitly selected cross-generation dependencies.
 pub fn candidate_matches_dep_for_recipe(
     c: &Candidate,
     dep: &ResolvedDep,
@@ -2377,9 +2377,8 @@ builddependencies = [
 
     #[test]
     fn checksum_lint_flags_patch_checksum_in_source_slot() {
-        // The eOn-2026.1 incident: the patch checksum inserted at position 1
-        // (a source slot). Counts match, so only positional key matching
-        // catches it before eb aborts a build with "Missing checksum for X".
+        // Counts match, so only positional key matching catches a patch
+        // checksum occupying a source slot before EasyBuild starts the build.
         let r = checksum_recipe(
             "[{'app-1.0.tar.gz': 'aa11'}, {'App-1.0_fix.patch': 'dd44'},\n \
              {'sub-2.0.tar.gz': 'bb22'}, {'core-3.0.tar.gz': 'cc33'}]",

src/hierarchy.rs

@@ -840,10 +840,8 @@ mod tests {
 
     #[test]
     fn known_foss_2026_1_includes_required_levels() {
-        // foss-2026.1 is the landable target generation used across the eOn /
-        // QMCPACK fixtures and skills. It must be a known hierarchy so `plan`
-        // resolves dependency versions without a full easyconfigs robot that
-        // carries the foss-2026.1 toolchain-definition recipe.
+        // An embedded generation lets `plan` resolve dependency versions when
+        // the supplied robot lacks the matching toolchain-definition recipe.
         let h = known_hierarchy(&foss("2026.1")).expect("embedded foss-2026.1");
         let labels = h.member_labels();
         for need in [