Org assignment history, mobile support, and a correctness pass

Data model
- employee_assignments records org placement over time (valid_from/valid_to),
  written by a trigger on `employees` rather than inside each RPC: ~70
  `update employees` statements spread over fifteen migrations mean per-call
  bookkeeping would miss paths today and again with every future RPC. A
  partial unique index enforces the one-open-interval invariant the trigger
  relies on when closing the current row.
- The Organigramm gains a Stichtag (default today). Membership comes from
  entry/exit/karenz, past placement from the new history, future placement
  projected from pending_org_changes. Placements predating the migration are
  backfilled with today's values and flagged as such in the UI, since
  employee_history only ever stored free text and cannot be reconstructed.

Correctness
- Reports and exports silently truncated at PostgREST's 1000-row cap
  (db.max_rows); employee_history is already past it at ~800 staff. Every
  whole-table read now pages explicitly.
- XLSX date cells were a day early: ExcelJS converts a Date to an Excel
  serial straight off getTime(), so a Date built at local midnight lands on
  the previous day's serial in any positive-offset zone.
- Date handling is pinned to Europe/Vienna throughout, and date-only strings
  are formatted without a Date round-trip. The dashboard's YTD window was
  built by round-tripping a local Date through toISOString(), which shifted
  it a day early and dropped 31 December entirely.
- Export routes parsed measure/group/split/eventType with unchecked `as`
  casts, so an unknown value reached column headers as `undefined` and the
  Content-Disposition filename. Parsed against the label maps now, with the
  filename slugged as a backstop.
- toXlsx keyed columns by header text, silently dropping the second of any
  two columns sharing a name — split columns take their header from data.
- The org chart tree walks had no cycle guard; nothing in the schema forbids
  a manager_id cycle, and one would hang the tab rather than misreport.
- The login page reflected ?error= verbatim, letting anyone put arbitrary
  text on the real sign-in screen; messages are looked up by code now.
- React Flow needs elementsSelectable on, or it sets pointer-events:none on
  the whole node and the expand control stops responding.

UI
- Mobile: the shell was unusable below lg — a fixed 236px margin pushed
  content off-screen with no mobile navigation at all. The sidebar is now a
  drawer, dvh replaces vh, safe-area insets are honoured, inputs are 16px so
  iOS stops zooming on focus, and form grids stack.
- Org chart nodes redesigned: per-kind accent stripes and icons, vacant
  roles called out, expand control moved to the bottom edge carrying the
  child count.
- Pagination is windowed; it previously rendered one link per page (54 for
  the employee list, unbounded for the audit log).
- Positions page reduced to open positions with a single "Besetzen" action.
- The employee Organisation tab links into the org chart focused on that
  person, reusing the chart's existing search-match highlighting.

Also included, uncommitted until now
- Dependants, HR notes, academic titles, split address fields, position
  validity and role/employment fields, with their migrations and UI.
- Docker/compose deployment setup, data-model and security-review docs.

components/orgchart/EmployeeTree.tsx

@@ -2,13 +2,21 @@
 
 import { ChevronDown, ChevronRight, Search } from "lucide-react";
 import Link from "next/link";
-import { useMemo, useState } from "react";
+import { useCallback, useEffect, useMemo, useRef, useState } from "react";
 import { Avatar } from "@/components/ui/Avatar";
-import type { OrgEmployee } from "./types";
+import { SegmentedControl } from "@/components/ui/SegmentedControl";
+import { LazyGraphOrgChart } from "./LazyGraphOrgChart";
+import type { ChartNode, OrgEmployee } from "./types";
 
-export function EmployeeTree({ employees }: { employees: OrgEmployee[] }) {
-  const [expanded, setExpanded] = useState<Set<string>>(new Set());
+type ViewMode = "list" | "graph";
+
+export function EmployeeTree({ employees, focusId = null }: { employees: OrgEmployee[]; focusId?: string | null }) {
+  // Seeded with the focus target so their own reports are already unfolded;
+  // the chain *above* them comes from ancestorExpandIds.
+  const [expanded, setExpanded] = useState<Set<string>>(() => (focusId ? new Set([focusId]) : new Set()));
   const [query, setQuery] = useState("");
+  const [mode, setMode] = useState<ViewMode>("list");
+  const focusRef = useRef<HTMLDivElement>(null);
 
   const { childrenByManager, totalReportsById, root } = useMemo(() => {
     const byManager = new Map<string, OrgEmployee[]>();
@@ -19,22 +27,33 @@ export function EmployeeTree({ employees }: { employees: OrgEmployee[] }) {
     }
     for (const list of byManager.values()) list.sort((a, b) => a.last_name.localeCompare(b.last_name));
 
+    // Nothing in the schema forbids a manager_id cycle (A reports to B
+    // reports to A), and a reorg that moves a lead under one of their own
+    // reports would create one. Every walk below is recursive, so an
+    // unguarded cycle is an infinite recursion that hangs the tab rather
+    // than a wrong number — hence the on-path set.
     const totals = new Map<string, number>();
-    function countTotal(id: string): number {
-      if (totals.has(id)) return totals.get(id)!;
-      const direct = byManager.get(id) ?? [];
-      let total = direct.length;
-      for (const child of direct) total += countTotal(child.id);
+    function countTotal(id: string, path: Set<string>): number {
+      const memo = totals.get(id);
+      if (memo !== undefined) return memo;
+      if (path.has(id)) return 0;
+      path.add(id);
+      let total = 0;
+      for (const child of byManager.get(id) ?? []) total += 1 + countTotal(child.id, path);
+      path.delete(id);
       totals.set(id, total);
       return total;
     }
-    for (const e of employees) countTotal(e.id);
+    for (const e of employees) countTotal(e.id, new Set());
 
     return { childrenByManager: byManager, totalReportsById: totals, root: byManager.get("__root__") ?? [] };
   }, [employees]);
 
   const matchIds = useMemo(() => {
-    if (query.trim().length < 2) return null;
+    // A focus target behaves exactly like a search hit — same ancestor
+    // auto-expand, same ring, same fitView in graph mode — until the user
+    // starts typing, at which point their own search takes over.
+    if (query.trim().length < 2) return focusId ? new Set([focusId]) : null;
     const q = query.trim().toLowerCase();
     const matches = new Set<string>();
     for (const e of employees) {
@@ -47,7 +66,14 @@ export function EmployeeTree({ employees }: { employees: OrgEmployee[] }) {
       }
     }
     return matches;
-  }, [query, employees]);
+  }, [query, employees, focusId]);
+
+  // The chain above the focused person is auto-expanded, so the row only
+  // exists after that render — scroll once it does.
+  useEffect(() => {
+    if (!focusId) return;
+    focusRef.current?.scrollIntoView({ block: "center", behavior: "smooth" });
+  }, [focusId, mode]);
 
   const ancestorExpandIds = useMemo(() => {
     if (!matchIds) return null;
@@ -55,7 +81,7 @@ export function EmployeeTree({ employees }: { employees: OrgEmployee[] }) {
     const toExpand = new Set<string>();
     for (const id of matchIds) {
       let current = byId.get(id);
-      while (current?.manager_id) {
+      while (current?.manager_id && !toExpand.has(current.manager_id)) {
         toExpand.add(current.manager_id);
         current = byId.get(current.manager_id);
       }
@@ -63,21 +89,42 @@ export function EmployeeTree({ employees }: { employees: OrgEmployee[] }) {
     return toExpand;
   }, [matchIds, employees]);
 
-  function toggle(id: string) {
+  // useCallback-stable: GraphOrgChart's layout memo depends on this
+  // reference, so an unstable function would force a Dagre re-layout on
+  // every unrelated re-render.
+  const toggle = useCallback((id: string) => {
     setExpanded((prev) => {
       const next = new Set(prev);
       if (next.has(id)) next.delete(id);
       else next.add(id);
       return next;
     });
-  }
+  }, []);
 
-  function isExpanded(id: string): boolean {
-    return expanded.has(id) || (ancestorExpandIds?.has(id) ?? false);
-  }
+  const isExpanded = useCallback((id: string): boolean => expanded.has(id) || (ancestorExpandIds?.has(id) ?? false), [expanded, ancestorExpandIds]);
 
-  function renderNode(e: OrgEmployee, depth: number) {
-    const children = childrenByManager.get(e.id) ?? [];
+  const chartTree = useMemo<ChartNode[]>(() => {
+    function toChartNode(e: OrgEmployee, ancestors: Set<string>): ChartNode {
+      const children = ancestors.has(e.id) ? [] : (childrenByManager.get(e.id) ?? []);
+      const total = totalReportsById.get(e.id) ?? 0;
+      const nextAncestors = new Set(ancestors).add(e.id);
+      return {
+        id: e.id,
+        kind: "person",
+        label: `${e.first_name} ${e.last_name}`,
+        sublabel: e.job_title,
+        href: `/employees/${e.id}`,
+        avatar: { firstName: e.first_name, lastName: e.last_name },
+        totalReports: total,
+        matched: matchIds?.has(e.id) ?? false,
+        children: children.map((c) => toChartNode(c, nextAncestors)),
+      };
+    }
+    return root.map((r) => toChartNode(r, new Set()));
+  }, [root, childrenByManager, totalReportsById, matchIds]);
+
+  function renderNode(e: OrgEmployee, depth: number, ancestors: Set<string>) {
+    const children = ancestors.has(e.id) ? [] : (childrenByManager.get(e.id) ?? []);
     const hasChildren = children.length > 0;
     const expandedNow = isExpanded(e.id);
     const isMatch = matchIds?.has(e.id) ?? false;
@@ -86,6 +133,7 @@ export function EmployeeTree({ employees }: { employees: OrgEmployee[] }) {
     return (
       <div key={e.id}>
         <div
+          ref={e.id === focusId ? focusRef : undefined}
           className={`flex items-center gap-2 rounded px-2 py-1.5 hover:bg-surface ${isMatch ? "bg-brand-100" : ""}`}
           style={{ paddingLeft: depth * 24 + 8 }}
         >
@@ -109,7 +157,9 @@ export function EmployeeTree({ employees }: { employees: OrgEmployee[] }) {
             </span>
           )}
         </div>
-        {hasChildren && expandedNow && <div>{children.map((c) => renderNode(c, depth + 1))}</div>}
+        {hasChildren && expandedNow && (
+          <div>{children.map((c) => renderNode(c, depth + 1, new Set(ancestors).add(e.id)))}</div>
+        )}
       </div>
     );
   }
@@ -140,8 +190,13 @@ export function EmployeeTree({ employees }: { employees: OrgEmployee[] }) {
         >
           Alles einklappen
         </button>
+        <SegmentedControl<ViewMode> value={mode} onChange={setMode} options={[{ value: "list", label: "Liste" }, { value: "graph", label: "Grafisch" }]} />
       </div>
-      <div>{root.map((r) => renderNode(r, 0))}</div>
+      {mode === "list" ? (
+        <div>{root.map((r) => renderNode(r, 0, new Set()))}</div>
+      ) : (
+        <LazyGraphOrgChart tree={chartTree} isExpanded={isExpanded} onToggle={toggle} matchedIds={matchIds} />
+      )}
     </div>
   );
 }