tech-debt-backlog §5.14: clarify near-zero polysemy column display

examples/larql-polysemantic-hierarchical.q.orca.md

@@ -135,15 +135,21 @@ exposes the four-tier structure in the clearest form:
 | eagle      (3)   | animals   | birds        | 0.335             | super-group-sib    |
 | strawberry (4)   | fruits    | berries      | 0.063             | cross-group        |
 | blueberry  (5)   | fruits    | berries      | 0.055             | cross-group        |
-| mango      (6)   | fruits    | tropical     | 0.000             | cross-group        |
-| papaya     (7)   | fruits    | tropical     | 0.000             | cross-group        |
+| mango      (6)   | fruits    | tropical     | ≈0.000 (1.1e-4)   | cross-group        |
+| papaya     (7)   | fruits    | tropical     | ≈0.000 (6.2e-5)   | cross-group        |
 | car        (8)   | vehicles  | land         | 0.063             | cross-group        |
 | bike       (9)   | vehicles  | land         | 0.055             | cross-group        |
 | plane     (10)   | vehicles  | air          | 0.140             | cross-group        |
 | drone     (11)   | vehicles  | air          | 0.079             | cross-group        |
 
 Four ordered tiers — **1.0** (self) → **0.88** (sub-cluster-mate) →
 **0.34 – 0.59** (super-group sibling) → **≤ 0.14** (cross-group).
+The `≈0.000` entries on rows 6 (mango) and 7 (papaya) are not exactly
+zero — they round to `0.000` at 3-decimal display but compute to
+`~1e-4`. The ASCII heatmap in the companion demo correctly renders
+them as blank under its `< 0.05` threshold; the inline scientific-
+notation magnitudes in the table preserve the non-zero structure for
+readers running `compute_concept_gram_mps` directly.
 Compare against `larql-polysemantic-clusters`'s flat 1.00 / 0.72 /
 ≲ 0.09 three-tier structure: that example demonstrates the *block*
 polysemantic phenomenon on the product manifold, this one lifts it to

openspec/changes/tech-debt-backlog/tasks.md

@@ -943,7 +943,7 @@ keep the 2026-05-01 cluster contiguous.
   asserts the new wording lands and the misleading "non-constant"
   phrase no longer appears for the all-constants case.
 
-- [ ] 5.14 **Polysemy column tabulates `0.000` for entries that
+- [x] 5.14 **Polysemy column tabulates `0.000` for entries that
   compute as ~`1e-4`.** Severity: LOW.
   `examples/larql-polysemantic-hierarchical.q.orca.md:138-139`
   claims `mango (6) → 0.000` and `papaya (7) → 0.000`. Actual
@@ -954,6 +954,18 @@ keep the 2026-05-01 cluster contiguous.
   zero". Fix optional — add a "≈" prefix on near-zero rows or
   document the rounding convention in the surrounding paragraph.
   (Source: 2026-05-01 PR #48 self-review.)
+  Did both: the two cells now read `≈0.000 (1.1e-4)` and
+  `≈0.000 (6.2e-5)` so the magnitude is visible inline (verified
+  against `compute_concept_gram_mps` — mango = 1.091e-4, papaya =
+  6.169e-5), and a short paragraph after the tier-summary line
+  documents the rounding convention and points readers at the
+  demo's `< 0.05` heatmap threshold for cross-check. Other near-
+  zero columns (`strawberry`, `blueberry`, `car`, `bike` at ~0.06)
+  are already above the 3-dp rounding floor and keep their plain
+  `0.063` / `0.055` entries. No code or test changes — the
+  pipeline test `test_larql_polysemantic_hierarchical_pipeline`
+  parses the machine and recomputes the Gram, so its tier
+  assertions are unaffected by the prose/table edits.
 
 - [x] 5.15 **Documentation/contract polish on
   `MpsGramConfigurationError` and the compiler spec example.**