Polish export handoff artifacts

CHANGELOG.md

@@ -7,6 +7,14 @@
 
 # Changelog
 
+## Sprint 93 export handoff artifact polish (2026-06-21)
+
+- Added a latest handoff artifacts section to the Export Center for project reports, project metadata, dataset GeoJSON, detection GeoJSON and segmentation GeoJSON.
+- Reused existing preview/download export actions from each latest artifact card without changing export API contracts or persistence.
+- Added responsive styling for latest artifact cards, empty artifact states and compact artifact actions.
+- Added regression coverage for grouped latest artifact surfaces and preserved preview/download controls.
+- No API contracts, migrations, provider fetching or AI/model behavior changed.
+
 ## Sprint 92 workflow rail interaction polish (2026-06-21)
 
 - Audited the live Overview workflow rail click path from Overview to Data, Map, QA/QC and Exports.

backend/tests/test_sprint93_export_handoff_completion.py

@@ -0,0 +1,45 @@
+from pathlib import Path
+
+
+ROOT = Path(__file__).resolve().parents[2]
+
+
+def test_export_center_groups_latest_handoff_artifacts_by_type() -> None:
+    export_center = (ROOT / "frontend" / "src" / "components" / "exports" / "ExportCenter.tsx").read_text(
+        encoding="utf-8"
+    )
+
+    assert "latestHandoffArtifacts" in export_center
+    assert "Latest handoff artifacts" in export_center
+    assert "Project report" in export_center
+    assert "Project metadata" in export_center
+    assert "Dataset GeoJSON" in export_center
+    assert "Detection GeoJSON" in export_center
+    assert "Segmentation GeoJSON" in export_center
+    assert "latest-artifact-grid" in export_center
+    assert "latest-artifact-card" in export_center
+    assert "No artifact yet" in export_center
+
+
+def test_export_center_latest_artifact_cards_keep_existing_actions() -> None:
+    export_center = (ROOT / "frontend" / "src" / "components" / "exports" / "ExportCenter.tsx").read_text(
+        encoding="utf-8"
+    )
+
+    assert "getLatestExportByType" in export_center
+    assert "const item = artifact.item" in export_center
+    assert "canPreviewJson(item)" in export_center
+    assert "onPreviewContent(item.id)" in export_center
+    assert "onDownload(item.id)" in export_center
+    assert "compactPath(item.storage_path)" in export_center
+    assert "formatExportCreated(item.created_at)" in export_center
+
+
+def test_export_center_latest_artifact_styles_are_responsive() -> None:
+    css = (ROOT / "frontend" / "src" / "styles" / "app.css").read_text(encoding="utf-8")
+
+    assert ".latest-artifact-grid" in css
+    assert ".latest-artifact-card" in css
+    assert ".latest-artifact-card-empty" in css
+    assert ".latest-artifact-actions" in css
+    assert "grid-template-columns: repeat(auto-fit, minmax(12rem, 1fr));" in css

docs/CODEX_EXECUTION_LOG.md

@@ -3342,3 +3342,30 @@ Limitations:
 
 Next recommended pass:
 - After deploy and live validation, continue with export artifact action ergonomics or QA result drill-down, depending on the next live friction point.
+
+## Sprint 93 export handoff artifact polish (2026-06-21)
+
+Changed:
+- Added a `Latest handoff artifacts` section to `frontend/src/components/exports/ExportCenter.tsx`.
+- Grouped newest persisted artifacts for project report, project metadata, dataset GeoJSON, detection GeoJSON and segmentation GeoJSON.
+- Reused existing JSON preview and artifact download callbacks from latest artifact cards.
+- Added responsive latest artifact card styling in `frontend/src/styles/app.css`.
+- Added `backend/tests/test_sprint93_export_handoff_completion.py` to lock the grouped handoff surface, actions and responsive CSS.
+- Updated `CHANGELOG.md`, `docs/TODO.md` and `frontend/README.md`.
+
+Tested:
+- Red step: `python -m pytest backend\tests\test_sprint93_export_handoff_completion.py -q` failed on missing latest artifact grouping/actions/styles.
+- `python -m pytest backend\tests\test_sprint93_export_handoff_completion.py -q` (`3 passed`)
+- `python -m pytest backend\tests\test_sprint93_export_handoff_completion.py backend\tests\test_sprint64_export_handoff_polish.py backend\tests\test_sprint89_export_system_density.py backend\tests\test_sprint51_quality_export_polish.py backend\tests\test_sprint78_export_preview_readability.py -q` (`13 passed`)
+- `cd frontend && npm run typecheck`
+- `cd frontend && npm run build`
+- `bash scripts/run_readiness_check.sh` (`311 passed`; frontend typecheck/build passed; Alembic head `202606120900`; live smoke syntax passed)
+
+Open:
+- Tower deploy and live browser validation still pending for this pass.
+
+Limitations:
+- Export Center frontend handoff polish only; no API contract, persistence, migration, provider fetching or AI/model behavior changes.
+
+Next recommended pass:
+- After deploy and live validation, continue with QA/QC drilldown and map evidence layers.

docs/TODO.md

@@ -364,3 +364,4 @@ This file now starts with the current implementation status. Older preparation/b
 - [x] Add Overview workflow guidance for the V1 project -> data -> map -> QA/AI -> export path.
 - [x] Audit populated demo workflow and tighten complete-state Overview guidance copy.
 - [x] Make Overview workflow rail Map/Export clicks preserve useful dataset context.
+- [x] Add latest handoff artifact cards to the Export Center for report, metadata and GeoJSON outputs.

frontend/README.md

@@ -253,6 +253,7 @@ Detection Lab and Segmentation Lab now share the same AI workspace hierarchy: mo
 - Overview rail Map and Export clicks reuse the first ready vector/GeoJSON dataset when no layer or dataset is active, keeping the happy path connected without adding new API calls.
 - The Data workspace surfaces selected project, AOI and dataset context before creation/upload forms, then separates form and catalog/list regions for faster scanning.
 - The Export Center includes a handoff readiness summary, grouped artifact actions and provenance-rich export cards so report/GeoJSON handoff stays understandable in long-running demo projects.
+- The Export Center highlights the latest project report, project metadata, dataset GeoJSON, detection GeoJSON and segmentation GeoJSON artifacts with direct preview/download actions.
 
 ## Workbench shell refactor
 

frontend/src/components/exports/ExportCenter.tsx

@@ -51,6 +51,17 @@ function formatExportType(value: string): string {
     .join(' ')
 }
 
+function formatExportCreated(value?: string | null): string {
+  if (!value) {
+    return 'created time unavailable'
+  }
+  return value
+}
+
+function getLatestExportByType(exports: ExportRead[], exportType: string): ExportRead | null {
+  return exports.find((item) => item.export_type === exportType) ?? null
+}
+
 function exportMatchesSearch(item: ExportRead, query: string): boolean {
   const normalizedQuery = query.trim().toLowerCase()
   if (!normalizedQuery) {
@@ -90,6 +101,41 @@ export function ExportCenter({
   const handoffStatus = selectedProjectId ? 'project selected' : 'select project'
   const exportTypes = useMemo(() => Array.from(new Set(exports.map((item) => item.export_type))).sort(), [exports])
   const exportStatuses = useMemo(() => Array.from(new Set(exports.map((item) => item.status))).sort(), [exports])
+  const latestHandoffArtifacts = useMemo(
+    () => [
+      {
+        key: 'project_report_html',
+        label: 'Project report',
+        detail: 'HTML report for human review',
+        item: getLatestExportByType(exports, 'project_report_html'),
+      },
+      {
+        key: 'project_metadata_json',
+        label: 'Project metadata',
+        detail: 'Machine-readable project inventory',
+        item: getLatestExportByType(exports, 'project_metadata_json'),
+      },
+      {
+        key: 'dataset_geojson',
+        label: 'Dataset GeoJSON',
+        detail: 'Selected vector/reference layer',
+        item: getLatestExportByType(exports, 'dataset_geojson'),
+      },
+      {
+        key: 'detection_geojson',
+        label: 'Detection GeoJSON',
+        detail: 'Persisted detection geometries',
+        item: getLatestExportByType(exports, 'detection_geojson'),
+      },
+      {
+        key: 'segmentation_geojson',
+        label: 'Segmentation GeoJSON',
+        detail: 'Persisted segmentation polygons',
+        item: getLatestExportByType(exports, 'segmentation_geojson'),
+      },
+    ],
+    [exports],
+  )
   const filteredExports = useMemo(
     () =>
       exports.filter((item) => {
@@ -161,6 +207,42 @@ export function ExportCenter({
           </div>
         </div>
 
+        <div className="latest-artifact-surface" aria-label="Latest handoff artifacts">
+          <div>
+            <h3>Latest handoff artifacts</h3>
+            <p className="muted">Open the newest artifact of each handoff type without searching the full export history.</p>
+          </div>
+          <div className="latest-artifact-grid">
+            {latestHandoffArtifacts.map((artifact) => {
+              const item = artifact.item
+              return (
+                <div className={item ? 'latest-artifact-card' : 'latest-artifact-card latest-artifact-card-empty'} key={artifact.key}>
+                  <span>{artifact.label}</span>
+                  <strong>{item ? item.status : 'No artifact yet'}</strong>
+                  <p>{item ? compactPath(item.storage_path) : artifact.detail}</p>
+                  {item ? (
+                    <>
+                      <small>{formatExportCreated(item.created_at)}</small>
+                      <div className="latest-artifact-actions">
+                        {canPreviewJson(item) ? (
+                          <button type="button" className="secondary-action" onClick={() => onPreviewContent(item.id)}>
+                            Preview
+                          </button>
+                        ) : (
+                          <span className="status-badge">download-only</span>
+                        )}
+                        <button type="button" className="primary-action" onClick={() => onDownload(item.id)}>
+                          Download
+                        </button>
+                      </div>
+                    </>
+                  ) : null}
+                </div>
+              )
+            })}
+          </div>
+        </div>
+
         <div className="export-actions-surface" aria-label="Export artifact actions">
           <div className="panel-title-row">
             <div>

frontend/src/styles/app.css

@@ -1831,6 +1831,7 @@ button.entity-card {
 
 .export-summary-surface,
 .export-handoff-surface,
+.latest-artifact-surface,
 .export-actions-surface,
 .export-history-surface,
 .system-provider-capability-surface {
@@ -1849,6 +1850,10 @@ button.entity-card {
   background: #ffffff;
 }
 
+.latest-artifact-surface {
+  background: #ffffff;
+}
+
 .export-center-shell .quality-summary-grid {
   display: grid;
   grid-template-columns: repeat(auto-fit, minmax(8rem, 1fr));
@@ -1977,6 +1982,69 @@ button.entity-card {
   margin-top: 0;
 }
 
+.latest-artifact-grid {
+  display: grid;
+  grid-template-columns: repeat(auto-fit, minmax(12rem, 1fr));
+  gap: 0.6rem;
+}
+
+.latest-artifact-card {
+  display: grid;
+  min-width: 0;
+  gap: 0.36rem;
+  border: 1px solid rgba(15, 118, 110, 0.2);
+  border-radius: 8px;
+  padding: 0.72rem;
+  background: linear-gradient(180deg, #f8fcfa, #ffffff);
+}
+
+.latest-artifact-card-empty {
+  border-style: dashed;
+  border-color: var(--line);
+  background: var(--panel-soft);
+}
+
+.latest-artifact-card span {
+  color: var(--muted);
+  font-size: 0.68rem;
+  font-weight: 850;
+  letter-spacing: 0.05em;
+  text-transform: uppercase;
+}
+
+.latest-artifact-card strong {
+  overflow: hidden;
+  font-size: 0.9rem;
+  line-height: 1.24;
+  text-overflow: ellipsis;
+  white-space: nowrap;
+}
+
+.latest-artifact-card p,
+.latest-artifact-card small {
+  margin: 0;
+  color: var(--muted);
+  font-size: 0.8rem;
+  line-height: 1.35;
+  overflow-wrap: anywhere;
+}
+
+.latest-artifact-actions {
+  display: grid;
+  grid-template-columns: repeat(2, minmax(0, 1fr));
+  gap: 0.45rem;
+  align-items: center;
+  margin-top: 0.18rem;
+}
+
+.latest-artifact-actions button,
+.latest-artifact-actions .status-badge {
+  width: 100%;
+  min-height: 2.1rem;
+  justify-content: center;
+  text-align: center;
+}
+
 .export-type-badge {
   display: inline-flex;
   max-width: 100%;