B-META R2 fixes: reconcile slice() RoleKeySlice destructures across workers

B-fix-slices changed slice() return type from (usize, usize) tuple to
RoleKeySlice struct. Subsequent workers (B-fix-triangle, B-fix-parser via
trajectory.rs tests, markov_bundle tests) used the old tuple destructure.
This commit threads the new struct fields (slice.start, slice.stop)
through all consumers.

Tests: 289 pass on lance-graph-contract; 66 pass on deepnsm; 8 pass on
the integration_role_alignment test (THE test that should have blocked
PR #279).

Author: claude

crates/deepnsm/src/markov_bundle.rs

@@ -259,8 +259,8 @@ mod tests {
     fn bundle_does_not_rotate_subject_dims_outside_subject_slice() {
         // SUBJECT-only window: every sentence has a single SUBJECT token
         // whose content_fp is all 1.0 across the SUBJECT slice.
-        let subject_len = GrammaticalRole::Subject.slice().1
-            - GrammaticalRole::Subject.slice().0;
+        let subject_len = GrammaticalRole::Subject.slice().stop
+            - GrammaticalRole::Subject.slice().start;
         let sent = WindowedSentence {
             tokens: vec![TokenWithRole {
                 content_fp: vec![1.0; subject_len],
@@ -269,7 +269,9 @@ mod tests {
         };
         let traj = fill_and_bundle(Kernel::Uniform, 5, sent);
 
-        let (s_start, s_stop) = GrammaticalRole::Subject.slice();
+        let _slice = GrammaticalRole::Subject.slice();
+        let s_start = _slice.start;
+        let s_stop = _slice.stop;
         // SUBJECT slice should be non-zero (positive after normalization).
         let subject_sum: f32 =
             traj.fingerprint[s_start..s_stop].iter().sum();
@@ -296,8 +298,8 @@ mod tests {
     /// way symmetric kernels can't equalize.
     #[test]
     fn mexican_hat_bundle_differs_from_uniform_bundle() {
-        let subject_len = GrammaticalRole::Subject.slice().1
-            - GrammaticalRole::Subject.slice().0;
+        let subject_len = GrammaticalRole::Subject.slice().stop
+            - GrammaticalRole::Subject.slice().start;
         let radius = 5u32;
         let cap = (2 * radius + 1) as usize;
         // Single outlier at position 1 (delta = -4). Uniform weights this
@@ -338,8 +340,8 @@ mod tests {
     /// land in a loose [0.5, 1.5] band on a controlled SUBJECT-only window.
     #[test]
     fn bundle_l2_norm_invariant_to_kernel() {
-        let subject_len = GrammaticalRole::Subject.slice().1
-            - GrammaticalRole::Subject.slice().0;
+        let subject_len = GrammaticalRole::Subject.slice().stop
+            - GrammaticalRole::Subject.slice().start;
         let sent = WindowedSentence {
             tokens: vec![TokenWithRole {
                 content_fp: vec![1.0; subject_len],

crates/deepnsm/src/trajectory.rs

@@ -11,8 +11,8 @@ pub struct Trajectory {
 impl Trajectory {
     /// Slice the role band out of the trajectory's fingerprint.
     pub fn role_bundle(&self, role: GrammaticalRole) -> Vec<f32> {
-        let (start, stop) = role.slice();
-        self.role_bundle_range(start, stop)
+        let slice = role.slice();
+        self.role_bundle_range(slice.start, slice.stop)
     }
 
     /// Lower-level slice helper retained for test fixtures + callers
@@ -117,7 +117,9 @@ mod tests {
             radius: 5,
         };
         let bundle = t.role_bundle(GrammaticalRole::Subject);
-        let (start, stop) = GrammaticalRole::Subject.slice();
+        let _slice = GrammaticalRole::Subject.slice();
+        let start = _slice.start;
+        let stop = _slice.stop;
         assert_eq!(bundle.len(), stop - start);
     }
 
@@ -134,7 +136,9 @@ mod tests {
     fn role_candidates_filters_by_threshold() {
         // Codebook of 5 with similarities [0.9, 0.8, 0.4, 0.3, 0.1];
         // threshold 0.5 → only the first two pass.
-        let (start, stop) = GrammaticalRole::Subject.slice();
+        let _slice = GrammaticalRole::Subject.slice();
+        let start = _slice.start;
+        let stop = _slice.stop;
         let n = stop - start;
         let mut fingerprint = vec![0.0_f32; 16_384];
         for v in fingerprint[start..stop].iter_mut() {
@@ -181,7 +185,9 @@ mod tests {
     fn role_candidates_top_k_truncation() {
         // Codebook of 10 entries all above threshold — top_k=3 must
         // return exactly 3.
-        let (start, stop) = GrammaticalRole::Subject.slice();
+        let _slice = GrammaticalRole::Subject.slice();
+        let start = _slice.start;
+        let stop = _slice.stop;
         let n = stop - start;
         let mut fingerprint = vec![0.0_f32; 16_384];
         for v in fingerprint[start..stop].iter_mut() {