feat: expose recompute diagnostic repair tree

tests/facade.test.ts

@@ -707,6 +707,35 @@ test('expression cycles fail recompute without silently accepting a result', ()
   assert.equal(facade.getState().document.recompute?.objectStates.pocket, 'error')
 })
 
+test('recompute diagnostics expose root causes and repair only the affected branch', async () => {
+  const facade = createMockFacade()
+  facade.app.document.setExpression({ objectId: 'pad', propertyName: 'Length', expression: 'pocket.Length' })
+  facade.app.document.setExpression({ objectId: 'pocket', propertyName: 'Length', expression: 'pad.Length' })
+  const failed = facade.app.document.recompute()
+  assert.equal(failed.status, 'failed')
+
+  const diagnostics = facade.diagnostics.list().filter((diagnostic) => diagnostic.source === 'recompute')
+  const pocketRoot = diagnostics.find((diagnostic) => diagnostic.objectId === 'pocket' && diagnostic.code === 'DEPENDENCY_CYCLE')
+  const fillet = diagnostics.find((diagnostic) => diagnostic.objectId === 'fillet')
+  assert.ok(pocketRoot)
+  assert.equal(pocketRoot.generation, failed.generation)
+  assert.equal(pocketRoot.documentVersion, facade.app.document.getActive().version)
+  assert.equal(pocketRoot.repairActions?.find((action) => action.id === 'suppress-root')?.enabled, false)
+  assert.deepEqual(fillet?.dependencyPath, ['fillet', 'pocket'])
+  assert.equal(fillet?.rootCauseObjectId, 'pocket')
+
+  const tree = facade.diagnostics.tree()
+  assert.ok(tree.find((node) => node.diagnostic.id === pocketRoot.id)?.children.some((node) => node.diagnostic.objectId === 'fillet'))
+  const selected = await facade.diagnostics.repair(pocketRoot.id, 'select-object')
+  assert.equal(selected.status, 'completed')
+  assert.equal(facade.selection.getObjectId(), 'pocket')
+
+  facade.app.document.setExpression({ objectId: 'pad', propertyName: 'Length', expression: '25 mm' })
+  const repaired = await facade.diagnostics.repair(pocketRoot.id, 'recompute-root')
+  assert.equal(repaired.status, 'completed')
+  assert.equal(facade.diagnostics.list().some((diagnostic) => diagnostic.source === 'recompute'), false)
+})
+
 test('view properties do not mark the geometry object touched', () => {
   const facade = createMockFacade()
   facade.app.document.setProperty({ objectId: 'fillet', propertyName: 'Visibility', value: false })