feat(t-paliad-207): Verfahrensablauf + Fristenrechner polish (jurisdiction prefix, trigger-event, flag rows, rule links, R.19 label)

Five intertwined fixes m surfaced in the interactive session:

1. **Jurisdiction prefix on the picked proceeding** — the collapsed
   summary chip and the result header now read "UPC Verletzungsverfahren"
   / "DE Verletzungsklage (LG)" instead of the bare proceeding name.
   Disambiguates the 4 redundancies in the corpus once the picker
   collapses. Driven by .proceeding-group[data-forum] which is already
   on every group.

2. **Trigger Event label = root rule** — step 2's "Auslösendes Ereignis"
   line now shows the first event in the proceeding (e.g. Klageerhebung,
   Nichtigkeitsklage) instead of the proceeding name. Populated from
   the calc response (isRootEvent=true) on every render; em-dash
   placeholder while step 3 hasn't rendered yet. lang-change keeps it
   coherent.

3. **Flag rows on /tools/verfahrensablauf** — Slice 1 of t-paliad-179
   stripped the with_ccr / with_amend / with_cci toggles when it lifted
   the shared renderer; they never came back. Lifted the 4 existing
   rows from fristenrechner.tsx plus 2 new with_po rows (RoP 19.1
   preliminary objection, mig 095) — same wiring + show/hide rules on
   both surfaces. with_amend stays nested under with_ccr on upc.inf.cfi
   (R.30 only with a CCR).

4. **Rule references → youpc.org/laws links** — new
   BuildLegalSourceURL(src) maps the structured legal_source code to
   the youpc permalink for the UPC corpus (UPCRoP / UPCA / UPCS today;
   39 of 91 active rules carry UPC.RoP.* and now link). DE/EPA/EU
   bodies have no youpc home yet and render as plain display text —
   filed as m/paliad#39. Wired through UIDeadline.LegalSourceDisplay +
   LegalSourceURL so deadlineCardHtml can render <a target="_blank"
   rel="noopener"> when the URL is set.

5. **R.19 label: "Vorab-Einrede" → "Einspruch"** — m's correction. DE
   only (EN canonical UPC RoP term stays "Preliminary objection").
   Client-side change only — i18n + JSX fallbacks. The matching DB
   rename on the two rule-name rows folds into joule's broader mig 097
   (legal-citation backfill, t-paliad-208 follow-up). The live UPDATE
   applied during the session is captured under that audit reason; the
   no-op when joule's mig re-applies is harmless.

Build hygiene:
- go build ./... + go vet ./... clean
- new test TestBuildLegalSourceURL covers UPC corpus + DE/EPA/EU
  fall-through + edge cases (empty input, malformed source)
- bun run build clean (2417 i18n keys total)

Rebased on origin/main @ d126913 (ohm's submission_code rename
workstream B) — no conflicts in this commit's surface area.

Branch: mai/fermi/interactive-session. NOT self-merged.

frontend/src/client/fristenrechner.ts

@@ -112,23 +112,29 @@ async function calculate() {
   const priorityInput = document.getElementById("priority-date") as HTMLInputElement | null;
   const priorityDate = selectedType === "epa.grant.exa" && priorityInput?.value ? priorityInput.value : "";
 
-  // Flags — three proceeding-specific checkboxes:
+  // Flags — proceeding-specific checkboxes:
   //   upc.inf.cfi: with_ccr (always available); with_amend (nested under
-  //                with_ccr — R.30 application is only available with a CCR).
+  //                with_ccr — R.30 application is only available with a CCR);
-  //   upc.rev.cfi: with_amend (R.49.2.a) and with_cci (R.49.2.b) as two
+  //                with_po (mig 095, R.19.1 preliminary objection).
-  //                independent gates; both can be on simultaneously.
+  //   upc.rev.cfi: with_amend (R.49.2.a), with_cci (R.49.2.b),
+  //                with_po (R.19.1 via R.46) as three independent gates;
+  //                all combinations are valid.
   const ccrFlag      = document.getElementById("ccr-flag")        as HTMLInputElement | null;
   const infAmendFlag = document.getElementById("inf-amend-flag")  as HTMLInputElement | null;
+  const infPoFlag    = document.getElementById("inf-po-flag")     as HTMLInputElement | null;
   const revAmendFlag = document.getElementById("rev-amend-flag")  as HTMLInputElement | null;
   const revCciFlag   = document.getElementById("rev-cci-flag")    as HTMLInputElement | null;
+  const revPoFlag    = document.getElementById("rev-po-flag")     as HTMLInputElement | null;
   const flags: string[] = [];
   if (selectedType === "upc.inf.cfi") {
     if (ccrFlag?.checked)                          flags.push("with_ccr");
     if (ccrFlag?.checked && infAmendFlag?.checked) flags.push("with_amend");
+    if (infPoFlag?.checked)                        flags.push("with_po");
   }
   if (selectedType === "upc.rev.cfi") {
     if (revAmendFlag?.checked) flags.push("with_amend");
     if (revCciFlag?.checked)   flags.push("with_cci");
+    if (revPoFlag?.checked)    flags.push("with_po");
   }
 
   // Forward any user-set per-rule date overrides so downstream rules
@@ -508,18 +514,24 @@ function selectProceeding(btn: HTMLButtonElement) {
   //   ccr-flag       → upc.inf.cfi only
   //   inf-amend-flag → upc.inf.cfi only, but disabled until ccr-flag is on
   //                     (R.30 amend only available with a CCR)
+  //   inf-po-flag    → upc.inf.cfi only (R.19.1 preliminary objection, mig 095)
   //   rev-amend-flag → upc.rev.cfi only
   //   rev-cci-flag   → upc.rev.cfi only
+  //   rev-po-flag    → upc.rev.cfi only (R.19.1 via R.46, mig 095)
   const priorityRow = document.getElementById("priority-date-row");
   if (priorityRow) priorityRow.style.display = selectedType === "epa.grant.exa" ? "" : "none";
   const ccrRow = document.getElementById("ccr-flag-row");
   if (ccrRow) ccrRow.style.display = selectedType === "upc.inf.cfi" ? "" : "none";
   const infAmendRow = document.getElementById("inf-amend-flag-row");
   if (infAmendRow) infAmendRow.style.display = selectedType === "upc.inf.cfi" ? "" : "none";
+  const infPoRow = document.getElementById("inf-po-flag-row");
+  if (infPoRow) infPoRow.style.display = selectedType === "upc.inf.cfi" ? "" : "none";
   const revAmendRow = document.getElementById("rev-amend-flag-row");
   if (revAmendRow) revAmendRow.style.display = selectedType === "upc.rev.cfi" ? "" : "none";
   const revCciRow = document.getElementById("rev-cci-flag-row");
   if (revCciRow) revCciRow.style.display = selectedType === "upc.rev.cfi" ? "" : "none";
+  const revPoRow = document.getElementById("rev-po-flag-row");
+  if (revPoRow) revPoRow.style.display = selectedType === "upc.rev.cfi" ? "" : "none";
 
   syncInfAmendEnabled();
   populateCourtPickerCore("court-picker-row", "court-picker", selectedType);
@@ -620,10 +632,14 @@ document.addEventListener("DOMContentLoaded", () => {
 
   const infAmendFlag = document.getElementById("inf-amend-flag") as HTMLInputElement | null;
   if (infAmendFlag) infAmendFlag.addEventListener("change", () => scheduleProcCalc(0));
+  const infPoFlag = document.getElementById("inf-po-flag") as HTMLInputElement | null;
+  if (infPoFlag) infPoFlag.addEventListener("change", () => scheduleProcCalc(0));
   const revAmendFlag = document.getElementById("rev-amend-flag") as HTMLInputElement | null;
   if (revAmendFlag) revAmendFlag.addEventListener("change", () => scheduleProcCalc(0));
   const revCciFlag = document.getElementById("rev-cci-flag") as HTMLInputElement | null;
   if (revCciFlag) revCciFlag.addEventListener("change", () => scheduleProcCalc(0));
+  const revPoFlag = document.getElementById("rev-po-flag") as HTMLInputElement | null;
+  if (revPoFlag) revPoFlag.addEventListener("change", () => scheduleProcCalc(0));
   const courtPicker = document.getElementById("court-picker") as HTMLSelectElement | null;
   if (courtPicker) courtPicker.addEventListener("change", () => scheduleProcCalc(0));
 

frontend/src/client/i18n.ts

@@ -221,8 +221,10 @@ const translations: Record<Lang, Record<string, string>> = {
     "deadlines.court.label": "Gericht:",
     "deadlines.flag.ccr": "Mit Widerklage auf Nichtigkeit",
     "deadlines.flag.inf_amend": "Mit Antrag auf Patentänderung (R.30)",
+    "deadlines.flag.inf_po": "Mit Einspruch (R.19)",
     "deadlines.flag.rev_amend": "Mit Antrag auf Patentänderung (R.49.2.a)",
     "deadlines.flag.rev_cci": "Mit Verletzungswiderklage (R.49.2.b)",
+    "deadlines.flag.rev_po": "Mit Einspruch (R.19 i.V.m. R.46)",
     "deadlines.calculate": "Fristen berechnen",
     "deadlines.print": "Drucken",
     "deadlines.reset": "\u2190 Neu berechnen",
@@ -2788,8 +2790,10 @@ const translations: Record<Lang, Record<string, string>> = {
     "deadlines.court.label": "Court:",
     "deadlines.flag.ccr": "Counterclaim for revocation filed",
     "deadlines.flag.inf_amend": "Application to amend the patent filed (R.30)",
+    "deadlines.flag.inf_po": "Preliminary objection filed (R.19)",
     "deadlines.flag.rev_amend": "Application to amend the patent filed (R.49.2.a)",
     "deadlines.flag.rev_cci": "Counterclaim for infringement filed (R.49.2.b)",
+    "deadlines.flag.rev_po": "Preliminary objection filed (R.19 via R.46)",
     "deadlines.calculate": "Calculate Deadlines",
     "deadlines.print": "Print",
     "deadlines.reset": "\u2190 Start Over",

frontend/src/client/verfahrensablauf.ts

@@ -25,6 +25,35 @@ let lastResponse: DeadlineResponse | null = null;
 type ProcedureView = "timeline" | "columns";
 let procedureView: ProcedureView = "columns";
 
+// Jurisdiction display prefix for the proceeding-summary chip + the
+// trigger-event placeholder. Same forum slugs the .proceeding-group
+// `data-forum` attribute carries in verfahrensablauf.tsx /
+// fristenrechner.tsx (upc / de / epa / dpma). Disambiguates the
+// 4 redundancies in the corpus (UPC Verletzungsverfahren vs DE
+// Verletzungsklage etc.) once the picker collapses.
+const FORUM_LABEL: Record<string, string> = {
+  upc: "UPC",
+  de: "DE",
+  epa: "EPA",
+  dpma: "DPMA",
+};
+
+function jurisdictionFor(btn: HTMLButtonElement): string {
+  const group = btn.closest<HTMLElement>(".proceeding-group");
+  const forum = group?.dataset.forum || "";
+  return FORUM_LABEL[forum] || "";
+}
+
+function proceedingDisplayName(btn: HTMLButtonElement): string {
+  const name = btn.querySelector("strong")?.textContent || "";
+  const jur = jurisdictionFor(btn);
+  return jur ? `${jur} ${name}` : name;
+}
+
+function activeProceedingButton(): HTMLButtonElement | null {
+  return document.querySelector<HTMLButtonElement>(".proceeding-btn.active");
+}
+
 // Auto-calc plumbing — sequence + debounce mirror /tools/fristenrechner
 // so rapid input changes never let a stale response overwrite a fresh
 // one.
@@ -46,6 +75,34 @@ function showStep(n: number) {
   }
 }
 
+// Read the proceeding-specific flag checkboxes and assemble the
+// payload the calculator expects. Mirrors fristenrechner.ts so the
+// gating semantics stay identical: with_amend on upc.inf.cfi is
+// nested under with_ccr (R.30 is only available with a CCR);
+// upc.rev.cfi exposes with_amend + with_cci as two independent
+// gates; with_po (RoP 19.1, mig 095) gates the optional preliminary
+// objection rule on both inf and rev.
+function readFlags(): string[] {
+  const ccr      = document.getElementById("ccr-flag")        as HTMLInputElement | null;
+  const infAmend = document.getElementById("inf-amend-flag")  as HTMLInputElement | null;
+  const infPo    = document.getElementById("inf-po-flag")     as HTMLInputElement | null;
+  const revAmend = document.getElementById("rev-amend-flag")  as HTMLInputElement | null;
+  const revCci   = document.getElementById("rev-cci-flag")    as HTMLInputElement | null;
+  const revPo    = document.getElementById("rev-po-flag")     as HTMLInputElement | null;
+  const flags: string[] = [];
+  if (selectedType === "upc.inf.cfi") {
+    if (ccr?.checked)                       flags.push("with_ccr");
+    if (ccr?.checked && infAmend?.checked)  flags.push("with_amend");
+    if (infPo?.checked)                     flags.push("with_po");
+  }
+  if (selectedType === "upc.rev.cfi") {
+    if (revAmend?.checked) flags.push("with_amend");
+    if (revCci?.checked)   flags.push("with_cci");
+    if (revPo?.checked)    flags.push("with_po");
+  }
+  return flags;
+}
+
 async function doCalc() {
   const seq = ++calcSeq;
   const dateInput = document.getElementById("trigger-date") as HTMLInputElement | null;
@@ -61,6 +118,7 @@ async function doCalc() {
   const data = await calculateDeadlines({
     proceedingType: selectedType,
     triggerDate,
+    flags: readFlags(),
     courtId,
   });
   if (seq !== calcSeq) return;
@@ -70,13 +128,42 @@ async function doCalc() {
   showStep(3);
 }
 
+// triggerEventLabelFor picks the user-facing "Auslösendes Ereignis"
+// label from the calc response. The root rule (isRootEvent=true) is
+// the first event in the proceeding — e.g. Klageerhebung for
+// upc.inf.cfi, Nichtigkeitsklage for upc.rev.cfi. Falls back to the
+// active proceeding name if no root rule fires (shouldn't happen for
+// healthy data, but safer than a blank).
+function triggerEventLabelFor(data: DeadlineResponse): string {
+  const root = data.deadlines.find((d) => d.isRootEvent);
+  if (root) {
+    return getLang() === "en" ? (root.nameEN || root.name) : (root.name || root.nameEN);
+  }
+  return data.proceedingName || "";
+}
+
+function syncTriggerEventLabel() {
+  const triggerEventEl = document.getElementById("trigger-event");
+  if (!triggerEventEl) return;
+  if (lastResponse) {
+    triggerEventEl.textContent = triggerEventLabelFor(lastResponse);
+  } else {
+    triggerEventEl.textContent = "—";
+  }
+}
+
 function renderResults(data: DeadlineResponse) {
   const container = document.getElementById("timeline-container");
   if (!container) return;
   const printBtn = document.getElementById("fristen-print-btn");
   const toggle = document.getElementById("fristen-view-toggle");
 
-  const procName = tDyn(`deadlines.${data.proceedingType.toLowerCase()}`);
+  // Header shows the picked proceeding with its jurisdiction prefix
+  // so the user can tell UPC Verletzungsverfahren apart from DE
+  // Verletzungsklage once the picker collapses.
+  const activeBtn = activeProceedingButton();
+  const procName = activeBtn ? proceedingDisplayName(activeBtn)
+    : tDyn(`deadlines.${data.proceedingType.toLowerCase()}`);
   const headerHtml = `<div class="timeline-header">
     <strong>${procName}</strong>
     <span class="timeline-trigger-date">${t("deadlines.trigger.label")}: ${formatDate(data.triggerDate)}</span>
@@ -89,6 +176,8 @@ function renderResults(data: DeadlineResponse) {
   container.innerHTML = headerHtml + bodyHtml;
   if (printBtn) printBtn.style.display = "block";
   if (toggle) toggle.style.display = "";
+
+  syncTriggerEventLabel();
 }
 
 function setProceedingPickerCollapsed(collapsed: boolean, displayName?: string) {
@@ -100,18 +189,49 @@ function setProceedingPickerCollapsed(collapsed: boolean, displayName?: string)
   if (summaryName && displayName) summaryName.textContent = displayName;
 }
 
+// syncFlagRows shows/hides the proceeding-specific checkbox rows
+// based on selectedType. Same disposition as fristenrechner.ts —
+// the with_amend nested-under-ccr semantic is enforced via
+// syncInfAmendEnabled().
+function syncFlagRows() {
+  const show = (id: string, when: boolean) => {
+    const el = document.getElementById(id);
+    if (el) el.style.display = when ? "" : "none";
+  };
+  show("ccr-flag-row",       selectedType === "upc.inf.cfi");
+  show("inf-amend-flag-row", selectedType === "upc.inf.cfi");
+  show("inf-po-flag-row",    selectedType === "upc.inf.cfi");
+  show("rev-amend-flag-row", selectedType === "upc.rev.cfi");
+  show("rev-cci-flag-row",   selectedType === "upc.rev.cfi");
+  show("rev-po-flag-row",    selectedType === "upc.rev.cfi");
+  syncInfAmendEnabled();
+}
+
+// R.30 amendment-application is only available with a CCR — disable
+// (and clear) the nested inf-amend checkbox while ccr is off so the
+// calc payload stays coherent. Mirrors fristenrechner.ts.
+function syncInfAmendEnabled() {
+  const ccr      = document.getElementById("ccr-flag")       as HTMLInputElement | null;
+  const infAmend = document.getElementById("inf-amend-flag") as HTMLInputElement | null;
+  if (!ccr || !infAmend) return;
+  infAmend.disabled = !ccr.checked;
+  if (!ccr.checked) infAmend.checked = false;
+}
+
 function selectProceeding(btn: HTMLButtonElement) {
   document.querySelectorAll(".proceeding-btn").forEach((b) => b.classList.remove("active"));
   btn.classList.add("active");
   selectedType = btn.dataset.code || "";
 
-  const name = btn.querySelector("strong")?.textContent || "";
+  // Trigger-event label fires from the calc response (root rule).
-  const triggerEventEl = document.getElementById("trigger-event");
+  // Until step 3 renders, fall back to an em-dash placeholder.
-  if (triggerEventEl) triggerEventEl.textContent = name;
+  lastResponse = null;
+  syncTriggerEventLabel();
 
   void populateCourtPicker("court-picker-row", "court-picker", selectedType);
+  syncFlagRows();
 
-  setProceedingPickerCollapsed(true, name);
+  setProceedingPickerCollapsed(true, proceedingDisplayName(btn));
 
   showStep(2);
   scheduleCalc(0);
@@ -169,18 +289,35 @@ document.addEventListener("DOMContentLoaded", () => {
   const courtPicker = document.getElementById("court-picker") as HTMLSelectElement | null;
   if (courtPicker) courtPicker.addEventListener("change", () => scheduleCalc(0));
 
+  // Flag-checkbox listeners — each flip triggers a fresh calc so the
+  // timeline re-projects with the new gating. ccr-flag additionally
+  // enables/disables the nested inf-amend row.
+  const ccrFlag = document.getElementById("ccr-flag") as HTMLInputElement | null;
+  if (ccrFlag) ccrFlag.addEventListener("change", () => {
+    syncInfAmendEnabled();
+    scheduleCalc(0);
+  });
+  (["inf-amend-flag", "inf-po-flag", "rev-amend-flag", "rev-cci-flag", "rev-po-flag"]).forEach((id) => {
+    const cb = document.getElementById(id) as HTMLInputElement | null;
+    if (cb) cb.addEventListener("change", () => scheduleCalc(0));
+  });
+
   document.getElementById("fristen-print-btn")?.addEventListener("click", () => window.print());
 
   initViewToggle();
 
   onLangChange(() => {
-    if (lastResponse) renderResults(lastResponse);
+    // Active-button name updates with language change (the data-i18n
-    const activeBtn = document.querySelector<HTMLButtonElement>(".proceeding-btn.active");
+    // pass swaps the inner <strong>'s text). Re-collapse the summary
+    // chip and re-derive the trigger event label from the lang-current
+    // calc response.
+    const activeBtn = activeProceedingButton();
     if (activeBtn) {
-      const name = activeBtn.querySelector("strong")?.textContent || "";
+      const summary = document.getElementById("proceeding-summary-name");
-      const triggerEventEl = document.getElementById("trigger-event");
+      if (summary) summary.textContent = proceedingDisplayName(activeBtn);
-      if (triggerEventEl) triggerEventEl.textContent = name;
     }
+    if (lastResponse) renderResults(lastResponse);
+    syncTriggerEventLabel();
   });
 
   // Pre-select the first proceeding tile so users see a timeline

frontend/src/client/views/verfahrensablauf-core.ts

@@ -38,6 +38,14 @@ export interface CalculatedDeadline {
   priority: "mandatory" | "recommended" | "optional" | "informational";
   ruleRef: string;
   legalSource?: string;
+  // legalSourceDisplay is the pretty form ("UPC RoP R.220(1)") produced
+  // by FormatLegalSourceDisplay on the backend. Renderer prefers this
+  // over ruleRef when set; falls back to ruleRef otherwise.
+  legalSourceDisplay?: string;
+  // legalSourceURL is the youpc.org/laws permalink when the cited body
+  // is hosted there (UPCRoP / UPCA / UPCS today). Empty for DE/EPA/EU
+  // bodies — the renderer shows display text without a link.
+  legalSourceURL?: string;
   notes?: string;
   notesEN?: string;
   dueDate: string;
@@ -240,9 +248,20 @@ export function deadlineCardHtml(dl: CalculatedDeadline, opts: CardOpts): string
     ? `<div class="timeline-adjusted">⚠ ${formatAdjustedNote(dl)}</div>`
     : "";
 
-  const ruleRef = dl.ruleRef
+  // Prefer the structured legalSource (pretty display + youpc.org link
-    ? `<span class="timeline-rule">${dl.ruleRef}</span>`
+  // when hosted there) over the bare rule_code fallback. UPC.RoP rules
-    : "";
+  // link to /laws/UPCRoP/<n>; DE / EPA / EU bodies have no youpc home
+  // yet so we render display text plain.
+  const legalDisplay = dl.legalSourceDisplay || "";
+  const legalURL = dl.legalSourceURL || "";
+  let ruleRef = "";
+  if (legalDisplay && legalURL) {
+    ruleRef = `<a class="timeline-rule timeline-rule--link" href="${escAttr(legalURL)}" target="_blank" rel="noopener noreferrer">${escHtml(legalDisplay)}</a>`;
+  } else if (legalDisplay) {
+    ruleRef = `<span class="timeline-rule">${escHtml(legalDisplay)}</span>`;
+  } else if (dl.ruleRef) {
+    ruleRef = `<span class="timeline-rule">${escHtml(dl.ruleRef)}</span>`;
+  }
 
   const noteText = getLang() === "en" ? (dl.notesEN || dl.notes) : dl.notes;
   const notes = noteText

frontend/src/fristenrechner.tsx

@@ -494,6 +494,12 @@ export function renderFristenrechner(): string {
                         <span data-i18n="deadlines.flag.inf_amend">Mit Antrag auf Patent&auml;nderung (R.30)</span>
                       </label>
                     </div>
+                    <div className="date-field-row" id="inf-po-flag-row" style="display:none">
+                      <label className="date-label">
+                        <input type="checkbox" id="inf-po-flag" />
+                        <span data-i18n="deadlines.flag.inf_po">Mit Einspruch (R.19)</span>
+                      </label>
+                    </div>
                     <div className="date-field-row" id="rev-amend-flag-row" style="display:none">
                       <label className="date-label">
                         <input type="checkbox" id="rev-amend-flag" />
@@ -506,6 +512,12 @@ export function renderFristenrechner(): string {
                         <span data-i18n="deadlines.flag.rev_cci">Mit Verletzungswiderklage (R.49.2.b)</span>
                       </label>
                     </div>
+                    <div className="date-field-row" id="rev-po-flag-row" style="display:none">
+                      <label className="date-label">
+                        <input type="checkbox" id="rev-po-flag" />
+                        <span data-i18n="deadlines.flag.rev_po">Mit Einspruch (R.19 i.V.m. R.46)</span>
+                      </label>
+                    </div>
                     <button type="button" id="calculate-btn" className="calculate-btn" data-i18n="deadlines.calculate">
                       Fristen berechnen
                     </button>

frontend/src/i18n-keys.ts

@@ -1026,8 +1026,10 @@ export type I18nKey =
   | "deadlines.filter.today"
   | "deadlines.flag.ccr"
   | "deadlines.flag.inf_amend"
+  | "deadlines.flag.inf_po"
   | "deadlines.flag.rev_amend"
   | "deadlines.flag.rev_cci"
+  | "deadlines.flag.rev_po"
   | "deadlines.form.approval_hint"
   | "deadlines.heading"
   | "deadlines.inbox.all"

frontend/src/verfahrensablauf.tsx

@@ -156,6 +156,47 @@ export function renderVerfahrensablauf(): string {
                       <label htmlFor="court-picker" className="date-label" data-i18n="deadlines.court.label">Gericht:</label>
                       <select id="court-picker" className="date-input"></select>
                     </div>
+                    {/* Proceeding-specific flag rows — mirror /tools/fristenrechner
+                         so an abstract-browse user can model the same variants
+                         (CCR, Patentänderung, Verletzungswiderklage,
+                         Vorab-Einrede). Show/hide driven by selectedType in
+                         the client. */}
+                    <div className="date-field-row" id="ccr-flag-row" style="display:none">
+                      <label className="date-label">
+                        <input type="checkbox" id="ccr-flag" />
+                        <span data-i18n="deadlines.flag.ccr">Mit Widerklage auf Nichtigkeit</span>
+                      </label>
+                    </div>
+                    <div className="date-field-row date-field-row--nested" id="inf-amend-flag-row" style="display:none">
+                      <label className="date-label">
+                        <input type="checkbox" id="inf-amend-flag" />
+                        <span data-i18n="deadlines.flag.inf_amend">Mit Antrag auf Patent&auml;nderung (R.30)</span>
+                      </label>
+                    </div>
+                    <div className="date-field-row" id="inf-po-flag-row" style="display:none">
+                      <label className="date-label">
+                        <input type="checkbox" id="inf-po-flag" />
+                        <span data-i18n="deadlines.flag.inf_po">Mit Einspruch (R.19)</span>
+                      </label>
+                    </div>
+                    <div className="date-field-row" id="rev-amend-flag-row" style="display:none">
+                      <label className="date-label">
+                        <input type="checkbox" id="rev-amend-flag" />
+                        <span data-i18n="deadlines.flag.rev_amend">Mit Antrag auf Patent&auml;nderung (R.49.2.a)</span>
+                      </label>
+                    </div>
+                    <div className="date-field-row" id="rev-cci-flag-row" style="display:none">
+                      <label className="date-label">
+                        <input type="checkbox" id="rev-cci-flag" />
+                        <span data-i18n="deadlines.flag.rev_cci">Mit Verletzungswiderklage (R.49.2.b)</span>
+                      </label>
+                    </div>
+                    <div className="date-field-row" id="rev-po-flag-row" style="display:none">
+                      <label className="date-label">
+                        <input type="checkbox" id="rev-po-flag" />
+                        <span data-i18n="deadlines.flag.rev_po">Mit Einspruch (R.19 i.V.m. R.46)</span>
+                      </label>
+                    </div>
                     <button type="button" id="calculate-btn" className="calculate-btn" data-i18n="deadlines.calculate">
                       Fristen berechnen
                     </button>

internal/services/deadline_search_service.go

@@ -870,6 +870,49 @@ func FormatLegalSourceDisplay(src string) string {
 	return b.String()
 }
 
+// BuildLegalSourceURL maps a structured legal_source code to a
+// youpc.org/laws permalink when the cited body is hosted there. Today
+// youpc only carries the UPC corpus (UPCA, UPCS, UPCRoP); DE national
+// codes (PatG, ZPO) and EPO bodies (EPÜ, EPC-R, RPBA) have no youpc
+// home yet, so the helper returns the empty string for those and the
+// caller renders the display string as plain text.
+//
+// Inputs mirror FormatLegalSourceDisplay — structured dot-separated
+// codes like UPC.RoP.220.1, UPC.UPCA.83. Sub-paragraph segments
+// beyond the law-number position are dropped; youpc resolves the page
+// at <type>/<number> granularity.
+//
+//	UPC.RoP.220.1 → https://youpc.org/laws/UPCRoP/220
+//	UPC.RoP.29.a  → https://youpc.org/laws/UPCRoP/29
+//	UPC.UPCA.83   → https://youpc.org/laws/UPCA/83
+//	DE.ZPO.276.1  → ""   (no youpc home — render display text plain)
+func BuildLegalSourceURL(src string) string {
+	src = strings.TrimSpace(src)
+	if src == "" {
+		return ""
+	}
+	parts := strings.Split(src, ".")
+	if len(parts) < 3 {
+		return ""
+	}
+	var lawType string
+	switch parts[0] + "." + parts[1] {
+	case "UPC.RoP":
+		lawType = "UPCRoP"
+	case "UPC.UPCA":
+		lawType = "UPCA"
+	case "UPC.UPCS":
+		lawType = "UPCS"
+	default:
+		return ""
+	}
+	number := parts[2]
+	if number == "" {
+		return ""
+	}
+	return "https://youpc.org/laws/" + lawType + "/" + number
+}
+
 // RefreshSearchView re-populates the materialised view. Safe to call on
 // every server boot — it's a CONCURRENTLY refresh against a < 1k row
 // view, well under 100 ms in practice. Called from cmd/server/main.go

internal/services/deadline_search_service_test.go

@@ -40,6 +40,37 @@ func TestFormatLegalSourceDisplay(t *testing.T) {
 	}
 }
 
+// TestBuildLegalSourceURL covers the structured-form → youpc.org/laws
+// permalink mapping. Only the UPC corpus has a youpc home today;
+// DE/EPA/EU bodies fall through to the empty string and the renderer
+// shows display text without a link.
+func TestBuildLegalSourceURL(t *testing.T) {
+	cases := []struct {
+		in, want string
+	}{
+		{"UPC.RoP.23.1", "https://youpc.org/laws/UPCRoP/23"},
+		{"UPC.RoP.139", "https://youpc.org/laws/UPCRoP/139"},
+		{"UPC.RoP.220.1", "https://youpc.org/laws/UPCRoP/220"},
+		{"UPC.RoP.29.a", "https://youpc.org/laws/UPCRoP/29"},
+		{"UPC.RoP.49.2.a", "https://youpc.org/laws/UPCRoP/49"},
+		{"UPC.UPCA.83", "https://youpc.org/laws/UPCA/83"},
+		{"UPC.UPCS.40.1", "https://youpc.org/laws/UPCS/40"},
+		{"DE.PatG.82.1", ""},
+		{"DE.ZPO.276.1", ""},
+		{"EU.EPÜ.108", ""},
+		{"EU.EPC-R.79.1", ""},
+		{"EU.RPBA.12.1.c", ""},
+		{"UPC.RoP", ""},
+		{"", ""},
+	}
+	for _, c := range cases {
+		got := BuildLegalSourceURL(c.in)
+		if got != c.want {
+			t.Errorf("BuildLegalSourceURL(%q) = %q, want %q", c.in, got, c.want)
+		}
+	}
+}
+
 // TestNormalizeQuery covers the input-side legal-prefix stripping that
 // keeps "§ 82" / "Art. 108" findable against structured legal_source
 // values that don't carry the prefix.

internal/services/fristenrechner.go

@@ -54,6 +54,15 @@ type UIDeadline struct {
 	Priority         string            `json:"priority"`
 	RuleRef          string            `json:"ruleRef"`
 	LegalSource      string            `json:"legalSource,omitempty"`
+	// LegalSourceDisplay is the pretty form (e.g. "UPC RoP R.220(1)")
+	// of LegalSource, produced by FormatLegalSourceDisplay. Frontend
+	// renders this in the deadline card meta line; falls back to
+	// RuleRef when LegalSource is empty.
+	LegalSourceDisplay string          `json:"legalSourceDisplay,omitempty"`
+	// LegalSourceURL is the youpc.org/laws permalink when the cited
+	// body is hosted there (UPCRoP / UPCA / UPCS today). Empty for
+	// DE/EPA/EU bodies — the renderer shows display text without a link.
+	LegalSourceURL   string            `json:"legalSourceURL,omitempty"`
 	Notes            string            `json:"notes,omitempty"`
 	NotesEN          string            `json:"notesEN,omitempty"`
 	DueDate          string            `json:"dueDate"`
@@ -283,6 +292,8 @@ func (s *FristenrechnerService) Calculate(ctx context.Context, proceedingCode, t
 		}
 		if r.LegalSource != nil {
 			d.LegalSource = *r.LegalSource
+			d.LegalSourceDisplay = FormatLegalSourceDisplay(*r.LegalSource)
+			d.LegalSourceURL = BuildLegalSourceURL(*r.LegalSource)
 		}
 		if r.DeadlineNotes != nil {
 			d.Notes = *r.DeadlineNotes
@@ -599,6 +610,7 @@ type RuleCalculationRule struct {
 	RuleRef            string  `json:"ruleRef,omitempty"`
 	LegalSource        string  `json:"legalSource,omitempty"`
 	LegalSourceDisplay string  `json:"legalSourceDisplay,omitempty"`
+	LegalSourceURL     string  `json:"legalSourceURL,omitempty"`
 	DurationValue      int     `json:"durationValue"`
 	DurationUnit       string  `json:"durationUnit"`
 	Party              string  `json:"party,omitempty"`
@@ -670,6 +682,7 @@ func (s *FristenrechnerService) CalculateRule(ctx context.Context, params CalcRu
 	if rule.LegalSource != nil {
 		out.Rule.LegalSource = *rule.LegalSource
 		out.Rule.LegalSourceDisplay = FormatLegalSourceDisplay(*rule.LegalSource)
+		out.Rule.LegalSourceURL = BuildLegalSourceURL(*rule.LegalSource)
 	}
 	if rule.PrimaryParty != nil {
 		out.Rule.Party = *rule.PrimaryParty
@@ -1217,6 +1230,8 @@ func (s *FristenrechnerService) calculateByTriggerEvent(
 		}
 		if r.LegalSource != nil {
 			d.LegalSource = *r.LegalSource
+			d.LegalSourceDisplay = FormatLegalSourceDisplay(*r.LegalSource)
+			d.LegalSourceURL = BuildLegalSourceURL(*r.LegalSource)
 		}
 		if r.DeadlineNotes != nil {
 			d.Notes = *r.DeadlineNotes