feat(reports): leftover-map singular values on grouping comparison graphic (v2.78.0)

AGENTS.md

@@ -637,6 +637,15 @@ that no persisted coordinate occupies. Do not invent leftover-map coordinate tic
 distance, leftover-map rank, leftover expected, leftover observed, leftover residual, leftover-map unexplained leftover, leftover-map reconstruction, leftover-map axis share, leftover-map post coverage, leftover-map item coverage,
 leftover-map incomplete post coverage, leftover-map incomplete item coverage, leftover pair
 count, or the count of unused axes.
+ADR 0321 captions leftover-map singular values on that grouping comparison leftover-map
+graphic from already-named leftover-map axes when that persisted `σ_k` is finite and
+non-negative. Rank-0 unused axes still name leftover-map comparison graphic leftover-map
+axis `σ 0.00`. Share and singular value omit independently. Do not invent leftover-map
+singular values from leftover-map axis share, leftover-map coordinate ticks, leftover-map
+distance, leftover-map rank, leftover expected, leftover observed, leftover residual,
+leftover-map unexplained leftover, leftover-map reconstruction, leftover-map post coverage,
+leftover-map item coverage, leftover-map incomplete post coverage, leftover-map incomplete
+item coverage, leftover pair count, or the count of unused axes.
 When `R`, `R̂`, `U`, `x`,
 `s`, and `e` are finite, `e + s + x = 1`. When `Y`, `E`, and `R` are
 finite, `Y − E = R`. When `R`, `R̂`, and `U` are
@@ -732,6 +741,9 @@ that grouping comparison leftover-map graphic with persisted leftover-map distan
 Grouping comparison leftover-map coordinate ticks (ADR 0320) captions
 that grouping comparison leftover-map graphic with persisted leftover-map coordinate
 ticks at the origin and at each unique finite `ξ` / `ζ` projection.
+Grouping comparison leftover-map singular values (ADR 0321) captions
+that grouping comparison leftover-map graphic with persisted leftover-map singular
+values `σ_k` when leftoverSingularForAxis returns a usable finite non-negative value.
 Item complete-case coverage
 (ADR 0282) captions the leftover-map graphic with how many scored criteria
 entered the map. Item complete-case coverage on the pair list (ADR 0285)

ARCHITECTURE.md

@@ -748,6 +748,8 @@ comparison leftover-map graphic when formatLeftoverMapDistance returns a usable
 badge.
 ADR 0320 captions leftover-map coordinate ticks on that grouping
 comparison leftover-map graphic from already-named leftover-map coordinates.
+ADR 0321 captions leftover-map singular values on that grouping
+comparison leftover-map graphic from already-named leftover-map axes.
 Click a post marker or a pair button
 opens that post. Those ADRs are the normative mathematical, storage, and
 display contracts. Leftover-map axis share
@@ -797,7 +799,8 @@ graphic (ADR 0316), leftover expected on the grouping comparison leftover-map
 graphic (ADR 0317), leftover-map rank on the grouping comparison leftover-map
 graphic (ADR 0318), leftover-map distance on the grouping comparison leftover-map
 graphic (ADR 0319), leftover-map coordinate ticks on the grouping comparison leftover-map
-graphic (ADR 0320);
+graphic (ADR 0320), leftover-map singular values on the grouping comparison leftover-map
+graphic (ADR 0321);
 `POST .../rebuild` scores every grouping kind (post_admin). `make seed`
 folds A-100/B-200 Event Lineage fixtures (and the Riverbend calendar
 post) that already have constructed IRT cells into the same shared

CHANGELOG.d/2.78.0-leftover-map-compare-plot-singular.md

@@ -0,0 +1,19 @@
+## 2.78.0 — Leftover-map singular values on grouping comparison leftover-map graphic
+
+- Caption leftover-map singular values on the grouping comparison leftover-map
+  graphic (ADR 0321). After `make seed`, closest and farthest leftover pairs
+  sit above the member list with leftover-map singular values `σ_k` on that
+  grouping comparison leftover-map graphic when those persisted singular values
+  are finite and non-negative; click a post marker or a pair button opens that
+  post. Rank-0 origin cells still name leftover-map comparison graphic leftover-map
+  axis `σ 0.00`. Comparison copy uses
+  `leftover map comparison graphic leftover-map axis {axis} σ {value}` so it
+  stays distinct from `leftover-map axis {axis} σ {value}`, from
+  `leftover axis {axis} σ {value}`, from
+  `leftover map comparison axis {axis} ({share}%)`, and from
+  `leftover map comparison graphic leftover-map axis {axis} tick {value}`.
+  Share and singular value omit independently. Do not invent `σ_k` from
+  leftover-map axis share. This increment does not caption leftover-map
+  singular values on leftover-axis report badges with a distinct name.
+  A finite negative leftover is shown, never clamped. Never invent a leftover
+  score. Never invent a theta. No new columns.

CHANGELOG.md

@@ -8,6 +8,24 @@ All notable changes to this project are documented here. Format follows
 
 ### Added
 
+- Period leftover pairs now name leftover-map singular values on the grouping
+  comparison leftover-map graphic (ADR 0321 / v2.78.0). After `make seed`,
+  closest and farthest leftover pairs sit above the member list with leftover-map
+  singular values `σ_k` on that grouping comparison leftover-map graphic when
+  those persisted singular values are finite and non-negative; click a post
+  marker or a pair button opens that post. Rank-0 origin cells still name
+  leftover-map comparison graphic leftover-map axis `σ 0.00`. Comparison copy
+  uses `leftover map comparison graphic leftover-map axis {axis} σ {value}` so
+  it stays distinct from `leftover-map axis {axis} σ {value}`, from
+  `leftover axis {axis} σ {value}`, from
+  `leftover map comparison axis {axis} ({share}%)`, and from
+  `leftover map comparison graphic leftover-map axis {axis} tick {value}`.
+  Share and singular value omit independently. Do not invent `σ_k` from
+  leftover-map axis share. This increment does not caption leftover-map
+  singular values on leftover-axis report badges with a distinct name.
+  A finite negative leftover is shown, never clamped. Never invent a leftover
+  score or a theta. No new columns.
+
 - Period leftover pairs now name leftover-map coordinate ticks on the grouping
   comparison leftover-map graphic (ADR 0320 / v2.77.0). After `make seed`,
   closest and farthest leftover pairs sit above the member list with leftover-map
@@ -18,9 +36,8 @@ All notable changes to this project are documented here. Format follows
   `leftover map comparison graphic leftover-map axis {axis} tick {value}` so it
   stays distinct from `leftover-map axis {axis} tick {value}` and from
   `leftover map comparison axis {axis} ({share}%)`. Do not invent evenly spaced
-  ticks that no persisted coordinate occupies. This increment does not caption
-  leftover-map singular values on the comparison graphic with a distinct name.
-  Do not invent leftover-map coordinate ticks from leftover-map distance.
+  ticks that no persisted coordinate occupies. Leftover-map singular values on
+  the comparison graphic are ADR 0321. Do not invent leftover-map coordinate ticks from leftover-map distance.
   A finite negative leftover is shown, never clamped. Never invent a leftover
   score or a theta. No new columns.
 

CLAUDE.md

@@ -49,7 +49,7 @@ cutoff. Global Ask optional `knowledge_cutoff` uses the same cover
 
 Create/start endpoint rules (ADR 0017 / 0021), tie-vs-miss similarity
 (ADR 0026), R&R catalog ids (ADR 0019 / 0027), leftover pairs
-(ADR 0048–0164 / 0182 / 0185 / 0201 / 0233 / 0266 / 0267 / 0268 / 0269 / 0270 / 0271 / 0272 / 0273 / 0274 / 0275 / 0276 / 0277 / 0278 / 0279 / 0280 / 0281 / 0282 / 0283 / 0284 / 0285 / 0286 / 0287 / 0288 / 0289 / 0290 / 0291 / 0292 / 0293 / 0294 / 0295 / 0296 / 0297 / 0298 / 0299 / 0300 / 0301 / 0302 / 0303 / 0304 / 0305 / 0306 / 0307 / 0308 / 0309 / 0310 / 0311 / 0312 / 0313 / 0314 / 0315 / 0316 / 0317 / 0318 / 0319 / 0320), occupational construct catalog search
+(ADR 0048–0164 / 0182 / 0185 / 0201 / 0233 / 0266 / 0267 / 0268 / 0269 / 0270 / 0271 / 0272 / 0273 / 0274 / 0275 / 0276 / 0277 / 0278 / 0279 / 0280 / 0281 / 0282 / 0283 / 0284 / 0285 / 0286 / 0287 / 0288 / 0289 / 0290 / 0291 / 0292 / 0293 / 0294 / 0295 / 0296 / 0297 / 0298 / 0299 / 0300 / 0301 / 0302 / 0303 / 0304 / 0305 / 0306 / 0307 / 0308 / 0309 / 0310 / 0311 / 0312 / 0313 / 0314 / 0315 / 0316 / 0317 / 0318 / 0319 / 0320 / 0321), occupational construct catalog search
 (ADR 0257), the text-channel embedding swap and cosine
 clamp (ADR 0190), per-edge channel-score persistence (ADR 0195),
 token-backed status notices (ADR 0220),

docs/adr/0320-leftover-map-compare-plot-ticks.md

@@ -3,6 +3,9 @@
 **Decision status:** Accepted
 **Date:** 2026-08-31
 
+**Amended by:** [ADR 0321](0321-leftover-map-compare-plot-singular.md)
+(leftover-map singular values on the grouping comparison leftover-map graphic)
+
 Amends leftover-map coordinate ticks on graphic-display axes
 ([ADR 0270](0270-leftover-map-coordinate-ticks.md)), leftover-map distance
 on the grouping comparison leftover-map graphic
@@ -12,7 +15,7 @@ on the grouping comparison leftover-map graphic
 display on the grouping comparison strip
 ([ADR 0304](0304-leftover-map-compare-graphic.md)), leftover-map coordinates
 ([ADR 0267](0267-leftover-map-coordinates.md)). Independent of leftover-map
-singular values on the grouping comparison leftover-map graphic.
+singular values on leftover-axis report badges.
 
 ## Context
 
@@ -95,7 +98,7 @@ and distance are finite, `R̂ = ξ · ζ` and `d = ‖ξ − ζ‖`.
 
 ## Related
 
-Independent of leftover-map singular values on the grouping comparison leftover-map graphic.
+Independent of leftover-map singular values on leftover-axis report badges.
 
 ## References
 

docs/adr/0321-leftover-map-compare-plot-singular.md

@@ -0,0 +1,111 @@
+# ADR 0321 — Name leftover-map singular values on the grouping comparison leftover-map graphic
+
+**Decision status:** Accepted
+**Date:** 2026-08-31
+
+Amends leftover-map coordinate ticks on the grouping comparison leftover-map
+graphic ([ADR 0320](0320-leftover-map-compare-plot-ticks.md)), leftover-map
+axis share on that comparison graphic
+([ADR 0305](0305-leftover-map-compare-plot-axis-share.md)), leftover-map
+graphic display on the grouping comparison strip
+([ADR 0304](0304-leftover-map-compare-graphic.md)), leftover-map axis share
+persistence ([ADR 0148](0148-leftover-map-axis-share.md)), leftover-map
+coordinates ([ADR 0267](0267-leftover-map-coordinates.md)). Independent of
+leftover-map singular values on leftover-axis report badges.
+
+## Context
+
+ADR 0148 already persists leftover-map singular values `σ_k` on
+`report_leftover_map_axis` together with leftover-map axis share
+`σ_k² / Σ_j σ_j²`. ADR 0305 already captions the grouping comparison
+leftover-map graphic with `leftover map comparison axis {k} ({share}%)`
+when that share is finite. ADR 0320 already ticks those comparison-graphic
+axes at persisted `ξ` / `ζ` projections. The comparison graphic still
+omits `σ_k`, so a buyer who compares leftover pairs can treat leftover-map
+axis share, leftover-map distance `d`, leftover-map rank, or leftover-map
+coordinate ticks as leftover-map structure without a next action. Gabriel
+inertia share is `σ_k² / Σ_j σ_j²`; hiding the persisted singular value
+lets share be read as a leftover score. A missing, non-finite, or negative
+singular value is not a leftover score and must omit independently of
+leftover-map axis share. Rank-0 unused axes still persist `σ_k = 0`.
+A finite negative leftover is shown, never clamped. Do not invent `σ_k`
+from leftover-map axis share.
+
+This increment captions leftover-map singular values on the grouping
+comparison leftover-map graphic from already-named leftover-map axes.
+Comparison copy uses the accessible names
+`leftover map comparison graphic leftover-map axis {axis} σ {value}` and
+`leftover map comparison graphic leftover-map axis {axis} σ {value} ({share}%)`
+so they stay distinct from hyphen `leftover-map axis {axis} σ {value}`,
+from pair-list `leftover axis {axis} σ {value}`, from comparison axis-share
+`leftover map comparison axis {axis} ({share}%)`, and from comparison
+coordinate ticks
+`leftover map comparison graphic leftover-map axis {axis} tick {value}`.
+It does not add columns. Do not invent a leftover score. Do not invent a
+theta.
+
+This protected increment uses **0321** so it does not collide with leftover-map
+coordinate ticks on the grouping comparison leftover-map graphic (0320),
+leftover-map distance on that graphic (0319), leftover-map axis share on that
+graphic (0305), leftover-map singular values on leftover-axis report badges,
+or the dashboard stacks.
+
+## Decision
+
+On the grouping comparison leftover-map graphic, caption leftover-map axis 1
+and leftover-map axis 2 with persisted leftover-map singular values `σ_k`
+when that singular value is finite and non-negative. Share and singular
+value omit independently: no share and no `σ_k` keeps
+`leftover map comparison axis {k}`; share only stays
+`leftover map comparison axis {k} ({share}%)`; `σ_k` only is
+`leftover map comparison graphic leftover-map axis {k} σ {value}`; both is
+`leftover map comparison graphic leftover-map axis {k} σ {value} ({share}%)`.
+A missing, non-finite, or negative singular value omits that `σ` badge and
+does not invent `σ_k` from leftover-map axis share. Rank-0 unused axes
+still name `σ 0.00`. Click a post marker to open that post. Criterion
+markers are not post buttons.
+
+Leftover-map comparison graphic leftover-map singular values omit
+independently of leftover-map comparison graphic leftover-map axis ticks
+and leftover-map axis share. A missing singular value omits that leftover-map
+comparison graphic leftover-map axis `σ` caption and keeps a usable
+leftover-map comparison axis share caption, leftover-map comparison graphic
+leftover-map axis ticks, leftover-map distance caption, leftover-map rank
+caption, leftover expected `E`, leftover observed `Y`, leftover residual `R`,
+leftover-map unexplained leftover `U`, leftover-map reconstruction `R̂`,
+and leftover-map comparison graphic coverage notes.
+
+This increment does not caption leftover-map singular values on leftover-axis
+report badges with a distinct comparison-strip name. Those leftover singular
+values already persist on leftover-map axes through ADR 0148. This increment
+does not persist leftover-map inner product, cosine, or length.
+
+Do not add SQL migrations. Do not edit shipped migrations. Do not invent a leftover
+score. Do not invent a theta.
+
+## Consequences
+
+After `make seed`, grouping comparison leftover pairs that already show
+the leftover-map graphic of persisted `ξ` / `ζ` also name leftover-map
+singular values on that graphic when those persisted `σ_k` are finite and
+non-negative. Rank-0 unused axes still plot at the origin and still name
+leftover-map comparison graphic leftover-map axis `σ 0.00`. Click a post
+marker or a pair button opens that post. When coordinates, reconstruction,
+and distance are finite, `R̂ = ξ · ζ` and `d = ‖ξ − ζ‖`. When leftover-map
+singular values and leftover-map axis share are finite,
+leftover-map axis share is `σ_k² / Σ_j σ_j²`.
+
+## Related
+
+Independent of leftover-map singular values on leftover-axis report badges.
+
+## References
+
+Jeon, M., Jin, I. H., Schweinberger, M., & Baugh, S. (2021). Mapping
+unobserved item–respondent interactions: A latent space item response
+model with interaction map. *Psychometrika, 86*(2), 378–403.
+https://doi.org/10.1007/s11336-021-09762-5
+
+Gabriel, K. R. (1971). The biplot graphic display of matrices with
+application to principal component analysis. *Biometrika, 58*(3),
+453–467. https://doi.org/10.1093/biomet/58.3.453

docs/product-technical-gap-baseline.md

@@ -1,5 +1,23 @@
 # Product & Technical Gap Baseline
 
+> Exact-head loop overlay: 2026-08-31 10:20 KST. Protected `main` is
+> `cb187cadee5fb6c46d8a944815ccc154a1e028d1`. Writes work. Do not
+> self-approve. #860 leftover-map coordinate ticks on the grouping comparison leftover-map
+> graphic (v2.77.0 / ADR 0320) is `40fa5bd`, stacked on #859 @ `9ba8535`. Independent
+> APPROVE is missing. Next buyer increment on this
+> cycle: leftover-map singular values on the grouping comparison leftover-map
+> graphic (ADR 0321 / v2.78.0) delivered locally on
+> `feat/leftover-map-compare-plot-singular-v2780`. Caption persisted leftover-map
+> singular values `σ_k` on that comparison graphic from already-named leftover-map
+> axes. Distinct accessible name `leftover map comparison graphic leftover-map
+> axis {axis} σ {value}`. Rank-0 unused axes still name `σ 0.00`. Share and
+> singular value omit independently. Do not invent `σ_k` from leftover-map axis
+> share. Do not caption leftover-map singular values on leftover-axis report
+> badges with a distinct name this increment. Stack onto #860.
+> Leave open for independent review. Do not squash-merge. Do not self-approve.
+> Issues #79 and #87 stay open. Do not merge #808 without independent APPROVE.
+> Never self-approve.
+
 > Exact-head loop overlay: 2026-08-31 09:28 KST. Protected `main` is
 > `cb187cadee5fb6c46d8a944815ccc154a1e028d1`. Writes work. Do not
 > self-approve. #859 leftover-map distance on the grouping comparison leftover-map

frontend/package.json

@@ -1,7 +1,7 @@
 {
   "name": "frontend",
   "private": true,
-  "version": "2.77.0",
+  "version": "2.78.0",
   "type": "module",
   "scripts": {
     "dev": "vite",

frontend/src/App.test.tsx

@@ -4197,8 +4197,8 @@ describe("App, authenticated", () => {
     expect(screen.getByLabelText("Leftover map comparison graphic")).toBeInTheDocument();
     expect(screen.getByText("leftover-map axis 1 (82%)")).toBeInTheDocument();
     expect(screen.getByText("leftover-map axis 2 (18%)")).toBeInTheDocument();
-    expect(screen.getByText("leftover map comparison axis 1 (82%)")).toBeInTheDocument();
-    expect(screen.getByText("leftover map comparison axis 2 (18%)")).toBeInTheDocument();
+    expect(screen.getByText("leftover map comparison graphic leftover-map axis 1 σ 1.84 (82%)")).toBeInTheDocument();
+    expect(screen.getByText("leftover map comparison graphic leftover-map axis 2 σ 0.86 (18%)")).toBeInTheDocument();
     expect(
       screen.getAllByRole("button", {
         name: /open leftover-map post public post at ξ \(\+0\.50, \+0\.10\)/i,
@@ -4322,12 +4322,12 @@ describe("App, authenticated", () => {
     ).not.toBeInTheDocument();
     expect(
       within(screen.getByLabelText("Grouping comparison")).getByText(
-        "leftover map comparison axis 1 (82%)",
+        "leftover map comparison graphic leftover-map axis 1 σ 1.84 (82%)",
       ),
     ).toBeInTheDocument();
     expect(
       within(screen.getByLabelText("Grouping comparison")).getByText(
-        "leftover map comparison axis 2 (18%)",
+        "leftover map comparison graphic leftover-map axis 2 σ 0.86 (18%)",
       ),
     ).toBeInTheDocument();
     expect(