Merge: t-paliad-349 docforge slice 6c — authoring page (frontend) (m/paliad#157)

The WYSIWYG authoring surface at /admin/templates (admin-gated page route):
  - templates-authoring.tsx — page shell (upload form, template list,
    workspace: palette / run-addressable preview / placed slots).
  - client/templates-authoring.ts — hydrates it: lists templates, uploads a
    .docx (multipart), renders the run-span preview, builds the variable
    palette from the Go catalogue (GET /api/docforge/variables), and wires
    the select-then-pick gesture: select text within one .docforge-run, click
    a palette variable → POST the slot → re-render with the response. Reuses
    the docforge-editor lib (escapeHtml, catalogue client). Cross-run
    selections rejected with a hint (v1: single-run text slots).
  - build.ts emits dist/templates-authoring.html + bundles the client.
  - handleTemplatesAuthoringPage serves the shell; GET /admin/templates
    registered under adminGate.
  - 12 i18n keys (DE+EN) for the page; i18n-keys.ts regenerated (3079).

Verification: go build/vet/test green (13 pkgs); bun run build.ts clean
(i18n scan passes); bun test 274/274; gofmt-clean. The docx surgery + store
+ catalogue are unit/live-tested. VERIFICATION CEILING: the integrated live
flow (upload→render→select→inject→save in a browser) needs the app running
with DATABASE_URL + Supabase auth + Playwright — verified post-merge, not in
this env.

m/paliad#157

cmd/server/main.go

@@ -174,6 +174,9 @@ func main() {
 		submissionComposerSvc := services.NewSubmissionComposer(submissionRenderer)
 		// t-paliad-315 Slice C — building-block library.
 		submissionBuildingBlockSvc := services.NewBuildingBlockService(pool, branding.Name)
+		// t-paliad-349 docforge slice 4/6 — uploaded-template store
+		// (Postgres bytea) backing the authoring surface.
+		templateStoreSvc := services.NewPgTemplateStore(pool)
 		// t-paliad-225 Slice A — user-authored checklist templates.
 		// Slice B adds checklist_shares grants + admin promotion.
 		checklistCatalogSvc := services.NewChecklistCatalogService(pool)
@@ -190,6 +193,7 @@ func main() {
 			SubmissionSection:       submissionSectionSvc,
 			SubmissionComposer:      submissionComposerSvc,
 			SubmissionBuildingBlock: submissionBuildingBlockSvc,
+			TemplateStore:           templateStoreSvc,
 			Deadline:       deadlineSvc,
 			Appointment:    appointmentSvc,
 			CalDAV:         caldavSvc,

frontend/build.ts

@@ -18,6 +18,7 @@ import { renderProjectsNew } from "./src/projects-new";
 import { renderProjectsDetail } from "./src/projects-detail";
 import { renderProjectsChart } from "./src/projects-chart";
 import { renderSubmissionDraft } from "./src/submission-draft";
+import { renderTemplatesAuthoring } from "./src/templates-authoring";
 import { renderSubmissionsIndex } from "./src/submissions-index";
 import { renderSubmissionsNew } from "./src/submissions-new";
 import { renderEvents } from "./src/events";
@@ -255,6 +256,7 @@ async function build() {
       join(import.meta.dir, "src/client/projects-detail.ts"),
       join(import.meta.dir, "src/client/projects-chart.ts"),
       join(import.meta.dir, "src/client/submission-draft.ts"),
+      join(import.meta.dir, "src/client/templates-authoring.ts"),
       join(import.meta.dir, "src/client/submissions-index.ts"),
       join(import.meta.dir, "src/client/submissions-new.ts"),
       join(import.meta.dir, "src/client/events.ts"),
@@ -382,6 +384,7 @@ async function build() {
   await Bun.write(join(DIST, "projects-detail.html"), renderProjectsDetail());
   await Bun.write(join(DIST, "projects-chart.html"), renderProjectsChart());
   await Bun.write(join(DIST, "submission-draft.html"), renderSubmissionDraft());
+  await Bun.write(join(DIST, "templates-authoring.html"), renderTemplatesAuthoring());
   await Bun.write(join(DIST, "submissions-index.html"), renderSubmissionsIndex());
   await Bun.write(join(DIST, "submissions-new.html"), renderSubmissionsNew());
   // t-paliad-115 — shared EventsPage at the canonical /events URL.

frontend/src/client/i18n.ts

@@ -1697,6 +1697,19 @@ const translations: Record<Lang, Record<string, string>> = {
     "submissions.draft.base.hint": "Steuert Schriftarten, Briefkopf und Abschnitts-Defaults.",
     "submissions.draft.sections.title": "Abschnitte",
     "submissions.draft.sections.hint": "Inhalt pro Abschnitt — Autosave nach 500 ms. Letztes Layout in Word.",
+    // t-paliad-349 (m/paliad#157) docforge slice 6 — template authoring page.
+    "templates.authoring.title": "Vorlagen — Paliad",
+    "templates.authoring.heading": "Vorlagen",
+    "templates.authoring.intro": "Lade eine Word-Vorlage hoch, markiere Stellen und setze Variablen ein.",
+    "templates.authoring.upload.title": "Neue Vorlage hochladen",
+    "templates.authoring.upload.file": "Word-Datei (.docx)",
+    "templates.authoring.upload.name_de": "Name (DE)",
+    "templates.authoring.upload.name_en": "Name (EN)",
+    "templates.authoring.upload.firm": "Kanzlei (optional)",
+    "templates.authoring.upload.submit": "Hochladen",
+    "templates.authoring.list.title": "Vorhandene Vorlagen",
+    "templates.authoring.workspace.hint": "Text markieren, dann eine Variable wählen, um einen Platzhalter zu setzen.",
+    "templates.authoring.slots.title": "Platzhalter",
     // t-paliad-315 (m/paliad#141) Composer Slice C — building blocks admin.
     "admin.building_blocks.title": "Bausteine — Paliad",
     "admin.building_blocks.heading": "Bausteine",
@@ -4962,6 +4975,19 @@ const translations: Record<Lang, Record<string, string>> = {
     "submissions.draft.base.hint": "Drives fonts, letterhead, and section defaults.",
     "submissions.draft.sections.title": "Sections",
     "submissions.draft.sections.hint": "Edit per section — autosaves after 500ms. Final layout in Word.",
+    // t-paliad-349 (m/paliad#157) docforge slice 6 — template authoring page.
+    "templates.authoring.title": "Templates — Paliad",
+    "templates.authoring.heading": "Templates",
+    "templates.authoring.intro": "Upload a Word template, highlight spots and insert variables.",
+    "templates.authoring.upload.title": "Upload a new template",
+    "templates.authoring.upload.file": "Word file (.docx)",
+    "templates.authoring.upload.name_de": "Name (DE)",
+    "templates.authoring.upload.name_en": "Name (EN)",
+    "templates.authoring.upload.firm": "Firm (optional)",
+    "templates.authoring.upload.submit": "Upload",
+    "templates.authoring.list.title": "Existing templates",
+    "templates.authoring.workspace.hint": "Highlight text, then pick a variable to place a placeholder.",
+    "templates.authoring.slots.title": "Placeholders",
     // t-paliad-315 (m/paliad#141) Composer Slice C — building blocks admin.
     "admin.building_blocks.title": "Building blocks — Paliad",
     "admin.building_blocks.heading": "Building blocks",

frontend/src/client/templates-authoring.ts

@@ -0,0 +1,314 @@
+import { initI18n } from "./i18n";
+import { initSidebar } from "./sidebar";
+import { escapeHtml } from "../lib/docforge-editor/dom";
+import { fetchVariableCatalogue, type VariableEntry } from "../lib/docforge-editor/catalogue";
+
+// t-paliad-349 docforge slice 6 — client for the template authoring page.
+//
+// Flow: list templates → upload a .docx (or open one) → the carrier renders
+// as run spans (<span class="docforge-run" data-run="N">) → the admin
+// selects text within one run, then clicks a variable in the palette → the
+// server injects {{slot}} at the selection and returns the updated view.
+//
+// The select-then-pick gesture keys on the run index (data-run) + the
+// selected text, matching the server's text-based InjectSlot so umlauts
+// can't desync the selection from the slice. Selections that span more than
+// one run are rejected with a hint (v1 scope: single-run text slots).
+
+interface TemplateMeta {
+  id: string;
+  slug?: string;
+  name_de: string;
+  name_en: string;
+  kind: string;
+  source_format: string;
+  firm?: string;
+  is_active: boolean;
+  version: number;
+}
+
+interface TemplateSlot {
+  key: string;
+  anchor: string;
+  label?: string;
+  order_index: number;
+}
+
+interface AuthoringView {
+  template: TemplateMeta;
+  preview_html: string;
+  slots: TemplateSlot[];
+}
+
+interface Selection1Run {
+  runIndex: number;
+  text: string;
+}
+
+interface State {
+  catalogue: VariableEntry[];
+  openID: string | null;
+  activeSlotKey: string | null;
+  selection: Selection1Run | null;
+}
+
+const state: State = {
+  catalogue: [],
+  openID: null,
+  activeSlotKey: null,
+  selection: null,
+};
+
+function isEN(): boolean {
+  return (document.documentElement.lang || "de").toLowerCase().startsWith("en");
+}
+
+function labelOf(e: VariableEntry): string {
+  return isEN() ? e.label_en : e.label_de;
+}
+
+async function boot(): Promise<void> {
+  initI18n();
+  initSidebar();
+
+  try {
+    state.catalogue = await fetchVariableCatalogue();
+  } catch (err) {
+    console.warn("templates-authoring: catalogue fetch failed", err);
+  }
+
+  wireUploadForm();
+  await loadList();
+}
+
+async function loadList(): Promise<void> {
+  const host = document.getElementById("docforge-template-list");
+  if (!host) return;
+  let metas: TemplateMeta[] = [];
+  try {
+    const res = await fetch("/api/admin/templates", { headers: { Accept: "application/json" } });
+    if (res.ok) {
+      const body = (await res.json()) as { templates: TemplateMeta[] };
+      metas = body.templates ?? [];
+    }
+  } catch (err) {
+    console.warn("templates-authoring: list fetch failed", err);
+  }
+  if (metas.length === 0) {
+    host.innerHTML = `<li class="docforge-template-empty">${escapeHtml(isEN() ? "No templates yet." : "Noch keine Vorlagen.")}</li>`;
+    return;
+  }
+  host.innerHTML = metas
+    .map((m) => {
+      const name = isEN() ? m.name_en : m.name_de;
+      const firm = m.firm ? ` · ${escapeHtml(m.firm)}` : "";
+      return `<li class="docforge-template-row" data-template-id="${escapeHtml(m.id)}">
+        <span class="docforge-template-name">${escapeHtml(name)}</span>
+        <span class="docforge-template-meta">v${m.version}${firm}</span>
+      </li>`;
+    })
+    .join("");
+  host.querySelectorAll<HTMLLIElement>(".docforge-template-row").forEach((li) => {
+    li.addEventListener("click", () => {
+      const id = li.dataset.templateId;
+      if (id) void openTemplate(id);
+    });
+  });
+}
+
+function wireUploadForm(): void {
+  const form = document.getElementById("docforge-upload-form") as HTMLFormElement | null;
+  if (!form) return;
+  form.addEventListener("submit", async (ev) => {
+    ev.preventDefault();
+    const status = document.getElementById("docforge-upload-status");
+    const data = new FormData(form);
+    setText(status, isEN() ? "Uploading…" : "Lädt hoch…");
+    try {
+      const res = await fetch("/api/admin/templates", { method: "POST", body: data });
+      if (!res.ok) {
+        const body = await res.json().catch(() => ({ error: `HTTP ${res.status}` }));
+        setText(status, (isEN() ? "Error: " : "Fehler: ") + (body.error ?? res.status));
+        return;
+      }
+      const view = (await res.json()) as AuthoringView;
+      setText(status, "");
+      form.reset();
+      await loadList();
+      openView(view);
+    } catch (err) {
+      setText(status, (isEN() ? "Error: " : "Fehler: ") + String(err));
+    }
+  });
+}
+
+async function openTemplate(id: string): Promise<void> {
+  try {
+    const res = await fetch(`/api/admin/templates/${encodeURIComponent(id)}`, {
+      headers: { Accept: "application/json" },
+    });
+    if (!res.ok) return;
+    openView((await res.json()) as AuthoringView);
+  } catch (err) {
+    console.warn("templates-authoring: open failed", err);
+  }
+}
+
+function openView(view: AuthoringView): void {
+  state.openID = view.template.id;
+  state.activeSlotKey = null;
+  state.selection = null;
+
+  const workspace = document.getElementById("docforge-workspace");
+  if (workspace) workspace.hidden = false;
+
+  const title = document.getElementById("docforge-workspace-title");
+  if (title) {
+    const name = isEN() ? view.template.name_en : view.template.name_de;
+    title.textContent = `${name} · v${view.template.version}`;
+  }
+
+  renderPreview(view.preview_html);
+  renderSlots(view.slots);
+  renderPalette();
+  setWorkspaceStatus("");
+}
+
+function renderPreview(html: string): void {
+  const host = document.getElementById("docforge-preview");
+  if (!host) return;
+  host.innerHTML = html;
+  host.addEventListener("mouseup", onPreviewSelect);
+}
+
+// onPreviewSelect captures a selection that lies entirely within one run
+// span; otherwise it clears the pending selection and hints.
+function onPreviewSelect(): void {
+  const sel = window.getSelection();
+  if (!sel || sel.isCollapsed || sel.rangeCount === 0) {
+    state.selection = null;
+    return;
+  }
+  const text = sel.toString();
+  if (text === "") {
+    state.selection = null;
+    return;
+  }
+  const anchorRun = closestRun(sel.anchorNode);
+  const focusRun = closestRun(sel.focusNode);
+  if (!anchorRun || anchorRun !== focusRun) {
+    state.selection = null;
+    setWorkspaceStatus(isEN()
+      ? "Select within a single text span."
+      : "Bitte innerhalb einer Textstelle markieren.");
+    return;
+  }
+  const runIndex = Number(anchorRun.dataset.run);
+  if (Number.isNaN(runIndex)) {
+    state.selection = null;
+    return;
+  }
+  state.selection = { runIndex, text };
+  setWorkspaceStatus(state.activeSlotKey
+    ? (isEN() ? `Click to bind “${text}” → ${state.activeSlotKey}` : `Variable wählen, um „${text}“ zu setzen`)
+    : (isEN() ? `Selected “${text}” — now pick a variable.` : `„${text}" markiert — jetzt Variable wählen.`));
+}
+
+function closestRun(node: Node | null): HTMLElement | null {
+  let el: Node | null = node;
+  while (el && el !== document.body) {
+    if (el instanceof HTMLElement && el.classList.contains("docforge-run")) return el;
+    el = el.parentNode;
+  }
+  return null;
+}
+
+// renderPalette groups catalogue entries by their namespace group and wires
+// each as a click-to-place control.
+function renderPalette(): void {
+  const host = document.getElementById("docforge-palette");
+  if (!host) return;
+  if (state.catalogue.length === 0) {
+    host.innerHTML = `<p class="docforge-palette-empty">${escapeHtml(isEN() ? "No variables." : "Keine Variablen.")}</p>`;
+    return;
+  }
+  const groups = new Map<string, VariableEntry[]>();
+  for (const e of state.catalogue) {
+    const arr = groups.get(e.group) ?? [];
+    arr.push(e);
+    groups.set(e.group, arr);
+  }
+  let html = `<h3>${escapeHtml(isEN() ? "Variables" : "Variablen")}</h3>`;
+  for (const [group, entries] of groups) {
+    html += `<div class="docforge-palette-group"><h4>${escapeHtml(group)}</h4>`;
+    for (const e of entries) {
+      html += `<button type="button" class="docforge-palette-var" data-slot-key="${escapeHtml(e.key)}" title="{{${escapeHtml(e.key)}}}">${escapeHtml(labelOf(e))}</button>`;
+    }
+    html += `</div>`;
+  }
+  host.innerHTML = html;
+  host.querySelectorAll<HTMLButtonElement>(".docforge-palette-var").forEach((btn) => {
+    btn.addEventListener("click", () => onPaletteClick(btn.dataset.slotKey ?? "", btn));
+  });
+}
+
+function onPaletteClick(slotKey: string, btn: HTMLButtonElement): void {
+  state.activeSlotKey = slotKey;
+  const host = document.getElementById("docforge-palette");
+  host?.querySelectorAll(".docforge-palette-var--active").forEach((el) => el.classList.remove("docforge-palette-var--active"));
+  btn.classList.add("docforge-palette-var--active");
+
+  if (state.selection) {
+    void placeSlot(state.selection.runIndex, state.selection.text, slotKey);
+  } else {
+    setWorkspaceStatus(isEN()
+      ? `${slotKey} selected — now highlight the text to replace.`
+      : `${slotKey} gewählt — jetzt den zu ersetzenden Text markieren.`);
+  }
+}
+
+async function placeSlot(runIndex: number, selectedText: string, slotKey: string): Promise<void> {
+  if (!state.openID) return;
+  setWorkspaceStatus(isEN() ? "Placing…" : "Setze…");
+  try {
+    const res = await fetch(`/api/admin/templates/${encodeURIComponent(state.openID)}/slots`, {
+      method: "POST",
+      headers: { "Content-Type": "application/json" },
+      body: JSON.stringify({ run_index: runIndex, selected_text: selectedText, slot_key: slotKey }),
+    });
+    if (!res.ok) {
+      const body = await res.json().catch(() => ({ error: `HTTP ${res.status}` }));
+      setWorkspaceStatus((isEN() ? "Error: " : "Fehler: ") + (body.error ?? res.status));
+      return;
+    }
+    openView((await res.json()) as AuthoringView);
+  } catch (err) {
+    setWorkspaceStatus((isEN() ? "Error: " : "Fehler: ") + String(err));
+  }
+}
+
+function renderSlots(slots: TemplateSlot[]): void {
+  const host = document.getElementById("docforge-slot-list");
+  if (!host) return;
+  if (slots.length === 0) {
+    host.innerHTML = `<li class="docforge-slot-empty">${escapeHtml(isEN() ? "No slots yet." : "Noch keine Platzhalter.")}</li>`;
+    return;
+  }
+  host.innerHTML = slots
+    .map((s) => `<li class="docforge-slot-row" data-slot="${escapeHtml(s.key)}"><code>{{${escapeHtml(s.key)}}}</code></li>`)
+    .join("");
+}
+
+function setWorkspaceStatus(msg: string): void {
+  setText(document.getElementById("docforge-workspace-status"), msg);
+}
+
+function setText(el: Element | null, msg: string): void {
+  if (el) el.textContent = msg;
+}
+
+if (document.readyState === "loading") {
+  document.addEventListener("DOMContentLoaded", () => void boot());
+} else {
+  void boot();
+}

frontend/src/i18n-keys.ts

@@ -2887,6 +2887,18 @@ export type I18nKey =
   | "team.selection.toggle_card"
   | "team.subtitle"
   | "team.title"
+  | "templates.authoring.heading"
+  | "templates.authoring.intro"
+  | "templates.authoring.list.title"
+  | "templates.authoring.slots.title"
+  | "templates.authoring.title"
+  | "templates.authoring.upload.file"
+  | "templates.authoring.upload.firm"
+  | "templates.authoring.upload.name_de"
+  | "templates.authoring.upload.name_en"
+  | "templates.authoring.upload.submit"
+  | "templates.authoring.upload.title"
+  | "templates.authoring.workspace.hint"
   | "theme.toggle.auto"
   | "theme.toggle.cycle.auto"
   | "theme.toggle.cycle.dark"

frontend/src/templates-authoring.tsx

@@ -0,0 +1,112 @@
+import { h } from "./jsx";
+import { Sidebar } from "./components/Sidebar";
+import { PaliadinWidget } from "./components/PaliadinWidget";
+import { BottomNav } from "./components/BottomNav";
+import { Footer } from "./components/Footer";
+import { PWAHead } from "./components/PWAHead";
+
+// t-paliad-349 docforge slice 6 — template authoring page at
+// /admin/templates.
+//
+// Admin uploads a base .docx, sees it rendered as run-addressable text,
+// selects a span + a variable from the palette to drop a {{slot}}, and the
+// result saves as a reusable docforge template. Pure shell:
+// client/templates-authoring.ts hydrates the list, upload form, preview,
+// palette, and slot list after load. The palette labels come from the Go
+// variable catalogue (GET /api/docforge/variables, the SSOT from slice 5).
+//
+// Design ref: docs/plans/prd-docforge-2026-05-29.md §2.1.
+
+export function renderTemplatesAuthoring(): string {
+  return "<!DOCTYPE html>" + (
+    <html lang="de">
+      <head>
+        <meta charset="UTF-8" />
+        <meta name="viewport" content="width=device-width, initial-scale=1, viewport-fit=cover" />
+        <meta name="theme-color" content="#BFF355" />
+        <PWAHead />
+        <title data-i18n="templates.authoring.title">Vorlagen &mdash; Paliad</title>
+        <link rel="stylesheet" href="/assets/global.css" />
+      </head>
+      <body className="has-sidebar page-templates-authoring">
+        <Sidebar currentPath="/admin" />
+        <BottomNav currentPath="/admin" />
+
+        <main>
+          <section className="tool-page docforge-templates-page">
+            <div className="container">
+              <header className="docforge-templates-header">
+                <h1 data-i18n="templates.authoring.heading">Vorlagen</h1>
+                <p
+                  className="docforge-templates-intro"
+                  data-i18n="templates.authoring.intro">
+                  Lade eine Word-Vorlage hoch, markiere Stellen und setze Variablen ein.
+                </p>
+              </header>
+
+              {/* Upload a new base .docx */}
+              <section className="docforge-upload" id="docforge-upload">
+                <h2 data-i18n="templates.authoring.upload.title">Neue Vorlage hochladen</h2>
+                <form id="docforge-upload-form" className="entity-form">
+                  <label className="entity-form-row">
+                    <span data-i18n="templates.authoring.upload.file">Word-Datei (.docx)</span>
+                    <input type="file" name="file" accept=".docx,.dotx,.docm,.dotm" required />
+                  </label>
+                  <label className="entity-form-row">
+                    <span data-i18n="templates.authoring.upload.name_de">Name (DE)</span>
+                    <input type="text" name="name_de" className="entity-form-input" required />
+                  </label>
+                  <label className="entity-form-row">
+                    <span data-i18n="templates.authoring.upload.name_en">Name (EN)</span>
+                    <input type="text" name="name_en" className="entity-form-input" required />
+                  </label>
+                  <label className="entity-form-row">
+                    <span data-i18n="templates.authoring.upload.firm">Kanzlei (optional)</span>
+                    <input type="text" name="firm" className="entity-form-input" />
+                  </label>
+                  <button type="submit" className="btn-primary" data-i18n="templates.authoring.upload.submit">
+                    Hochladen
+                  </button>
+                  <span className="docforge-upload-status" id="docforge-upload-status" />
+                </form>
+              </section>
+
+              {/* Existing templates */}
+              <section className="docforge-template-list-wrap">
+                <h2 data-i18n="templates.authoring.list.title">Vorhandene Vorlagen</h2>
+                <ul className="entity-table docforge-template-list" id="docforge-template-list" />
+              </section>
+
+              {/* Authoring workspace — hidden until a template is opened. */}
+              <section className="docforge-workspace" id="docforge-workspace" hidden>
+                <header className="docforge-workspace-header">
+                  <h2 id="docforge-workspace-title" />
+                  <span className="docforge-workspace-hint" data-i18n="templates.authoring.workspace.hint">
+                    Text markieren, dann eine Variable wählen, um einen Platzhalter zu setzen.
+                  </span>
+                  <span className="docforge-workspace-status" id="docforge-workspace-status" />
+                </header>
+                <div className="docforge-workspace-grid">
+                  {/* Variable palette (left) — populated from the catalogue. */}
+                  <aside className="docforge-palette" id="docforge-palette" />
+                  {/* Run-addressable preview (center) — selection target. */}
+                  <div className="docforge-preview" id="docforge-preview" />
+                  {/* Placed slots (right). */}
+                  <aside className="docforge-slots">
+                    <h3 data-i18n="templates.authoring.slots.title">Platzhalter</h3>
+                    <ul className="docforge-slot-list" id="docforge-slot-list" />
+                  </aside>
+                </div>
+              </section>
+            </div>
+          </section>
+        </main>
+
+        <Footer />
+        <PaliadinWidget />
+
+        <script src="/assets/templates-authoring.js"></script>
+      </body>
+    </html>
+  );
+}

internal/handlers/handlers.go

@@ -128,6 +128,10 @@ type Services struct {
 	// editor. Per Q2: paste sources only, no lineage on sections.
 	SubmissionBuildingBlock *services.BuildingBlockService
 
+	// t-paliad-349 docforge slice 4/6 — uploaded-template store backing
+	// the authoring surface.
+	TemplateStore *services.PgTemplateStore
+
 	// t-paliad-265 / m/paliad#96 — per-event-card optional choices on
 	// the Verfahrensablauf timeline.
 	EventChoice *services.EventChoiceService
@@ -215,6 +219,7 @@ func Register(mux *http.ServeMux, client *auth.Client, giteaAPIToken string, svc
 			submissionSection:       svc.SubmissionSection,
 			submissionComposer:      svc.SubmissionComposer,
 			submissionBuildingBlock: svc.SubmissionBuildingBlock,
+			templateStore:           svc.TemplateStore,
 			eventChoice:       svc.EventChoice,
 			scenario:          svc.Scenario,
 			scenarioFlags:     svc.ScenarioFlags,
@@ -750,6 +755,15 @@ func Register(mux *http.ServeMux, client *auth.Client, giteaAPIToken string, svc
 		protected.HandleFunc("GET /api/admin/backups/{id}", adminGate(users, handleAdminGetBackup))
 		protected.HandleFunc("GET /api/admin/backups/{id}/file", adminGate(users, handleAdminDownloadBackup))
 
+		// t-paliad-349 docforge slice 6 — template authoring surface
+		// (upload base .docx → place variable slots → save). Admin-only,
+		// firm-shared catalog like submission_bases.
+		protected.HandleFunc("GET /admin/templates", adminGate(users, gateOnboarded(handleTemplatesAuthoringPage)))
+		protected.HandleFunc("GET /api/admin/templates", adminGate(users, handleListTemplates))
+		protected.HandleFunc("POST /api/admin/templates", adminGate(users, handleUploadTemplate))
+		protected.HandleFunc("GET /api/admin/templates/{id}", adminGate(users, handleGetTemplateAuthoring))
+		protected.HandleFunc("POST /api/admin/templates/{id}/slots", adminGate(users, handlePlaceTemplateSlot))
+
 		protected.HandleFunc("GET /api/admin/users", adminGate(users, handleAdminListUsers))
 		protected.HandleFunc("POST /api/admin/users", adminGate(users, handleAdminCreateUser))
 		protected.HandleFunc("POST /api/admin/users/full", adminGate(users, handleAdminCreateFullUser))

internal/handlers/projects.go

@@ -77,6 +77,9 @@ type dbServices struct {
 	submissionComposer      *services.SubmissionComposer
 	submissionBuildingBlock *services.BuildingBlockService
 
+	// t-paliad-349 docforge slice 4/6 — uploaded-template store.
+	templateStore *services.PgTemplateStore
+
 	// t-paliad-265 — per-event-card optional choices.
 	eventChoice *services.EventChoiceService
 

internal/handlers/templates.go

@@ -0,0 +1,279 @@
+package handlers
+
+// docforge template authoring handlers (t-paliad-349 slice 6).
+//
+// The admin-only authoring surface: upload a base .docx, see it rendered as
+// run-addressable text, place {{variable}} slots into it, and save the
+// result as a reusable template. Backed by docforge.TemplateStore
+// (Postgres bytea carrier) + the docx authoring engine
+// (ImportForAuthoring / InjectSlot).
+//
+// Endpoints (all under adminGate — templates are firm-shared, admin-
+// authored, like submission_bases):
+//   GET  /api/admin/templates              — catalog list
+//   POST /api/admin/templates              — multipart upload → create v1
+//   GET  /api/admin/templates/{id}         — authoring view (preview+slots)
+//   POST /api/admin/templates/{id}/slots   — place a slot → new version
+//
+// Slot placement creates a new template version (immutable snapshot) per
+// placement. That keeps the snapshot guarantee simple; batching a whole
+// authoring session into one version on an explicit "save" is a documented
+// future refinement (it trades the version-per-slot churn for a client- or
+// session-held draft carrier).
+//
+// VERIFICATION CEILING: the live upload→render→select→inject→save flow
+// needs the app running with DATABASE_URL + Supabase auth + Playwright; it
+// is verified post-merge. The docx surgery (ImportForAuthoring/InjectSlot)
+// and the store are unit/live-tested independently.
+
+import (
+	"encoding/json"
+	"errors"
+	"fmt"
+	"io"
+	"net/http"
+
+	"mgit.msbls.de/m/paliad/pkg/docforge"
+	"mgit.msbls.de/m/paliad/pkg/docforge/docx"
+)
+
+// maxTemplateUpload bounds an uploaded .docx. Templates are firm letterhead
+// + chrome — tens of KB in practice; 10 MB is a generous ceiling.
+const maxTemplateUpload = 10 << 20
+
+type templateMetaJSON struct {
+	ID           string `json:"id"`
+	Slug         string `json:"slug,omitempty"`
+	NameDE       string `json:"name_de"`
+	NameEN       string `json:"name_en"`
+	Kind         string `json:"kind"`
+	SourceFormat string `json:"source_format"`
+	Firm         string `json:"firm,omitempty"`
+	IsActive     bool   `json:"is_active"`
+	Version      int    `json:"version"`
+}
+
+type templateSlotJSON struct {
+	Key        string `json:"key"`
+	Anchor     string `json:"anchor"`
+	Label      string `json:"label,omitempty"`
+	OrderIndex int    `json:"order_index"`
+}
+
+type authoringViewJSON struct {
+	Template    templateMetaJSON   `json:"template"`
+	PreviewHTML string             `json:"preview_html"`
+	Slots       []templateSlotJSON `json:"slots"`
+}
+
+func metaJSON(m docforge.TemplateMeta) templateMetaJSON {
+	return templateMetaJSON{
+		ID: m.ID, Slug: m.Slug, NameDE: m.NameDE, NameEN: m.NameEN,
+		Kind: m.Kind, SourceFormat: m.SourceFormat, Firm: m.Firm,
+		IsActive: m.IsActive, Version: m.Version,
+	}
+}
+
+func slotsJSON(slots []docforge.TemplateSlot) []templateSlotJSON {
+	out := make([]templateSlotJSON, 0, len(slots))
+	for _, s := range slots {
+		out = append(out, templateSlotJSON{Key: s.Key, Anchor: s.Anchor, Label: s.Label, OrderIndex: s.OrderIndex})
+	}
+	return out
+}
+
+// writeTemplateError maps docforge's not-found sentinel to 404 and falls
+// back to the shared service-error mapper.
+func writeTemplateError(w http.ResponseWriter, err error) {
+	if errors.Is(err, docforge.ErrTemplateNotFound) {
+		writeJSON(w, http.StatusNotFound, map[string]string{"error": "template not found"})
+		return
+	}
+	writeServiceError(w, err)
+}
+
+func requireTemplateStore(w http.ResponseWriter) bool {
+	if !requireDB(w) {
+		return false
+	}
+	if dbSvc.templateStore == nil {
+		writeJSON(w, http.StatusServiceUnavailable, map[string]string{"error": "template store not configured"})
+		return false
+	}
+	return true
+}
+
+// handleTemplatesAuthoringPage serves the authoring page shell. The client
+// bundle hydrates the list, upload, preview, palette, and slots.
+func handleTemplatesAuthoringPage(w http.ResponseWriter, r *http.Request) {
+	http.ServeFile(w, r, "dist/templates-authoring.html")
+}
+
+// handleListTemplates backs GET /api/admin/templates.
+func handleListTemplates(w http.ResponseWriter, r *http.Request) {
+	if !requireTemplateStore(w) {
+		return
+	}
+	if _, ok := requireUser(w, r); !ok {
+		return
+	}
+	metas, err := dbSvc.templateStore.List(r.Context(), docforge.TemplateFilter{ActiveOnly: true})
+	if err != nil {
+		writeTemplateError(w, err)
+		return
+	}
+	out := make([]templateMetaJSON, 0, len(metas))
+	for _, m := range metas {
+		out = append(out, metaJSON(m))
+	}
+	writeJSON(w, http.StatusOK, map[string]any{"templates": out})
+}
+
+// handleUploadTemplate backs POST /api/admin/templates (multipart). Reads
+// the uploaded .docx, validates it parses, detects any slots already in it,
+// and creates the template at version 1.
+func handleUploadTemplate(w http.ResponseWriter, r *http.Request) {
+	if !requireTemplateStore(w) {
+		return
+	}
+	uid, ok := requireUser(w, r)
+	if !ok {
+		return
+	}
+	if err := r.ParseMultipartForm(maxTemplateUpload); err != nil {
+		writeJSON(w, http.StatusBadRequest, map[string]string{"error": "invalid multipart form"})
+		return
+	}
+	file, _, err := r.FormFile("file")
+	if err != nil {
+		writeJSON(w, http.StatusBadRequest, map[string]string{"error": "file field required"})
+		return
+	}
+	defer file.Close()
+	carrier, err := io.ReadAll(io.LimitReader(file, maxTemplateUpload))
+	if err != nil {
+		writeJSON(w, http.StatusBadRequest, map[string]string{"error": "could not read uploaded file"})
+		return
+	}
+	nameDE := r.FormValue("name_de")
+	nameEN := r.FormValue("name_en")
+	if nameDE == "" || nameEN == "" {
+		writeJSON(w, http.StatusBadRequest, map[string]string{"error": "name_de and name_en required"})
+		return
+	}
+
+	// Validate + detect existing slots before persisting.
+	view, err := docx.ImportForAuthoring(carrier)
+	if err != nil {
+		writeJSON(w, http.StatusBadRequest, map[string]string{"error": "not a parseable .docx: " + err.Error()})
+		return
+	}
+
+	tmpl, err := dbSvc.templateStore.Create(r.Context(),
+		docforge.TemplateMetaInput{
+			Slug:      r.FormValue("slug"),
+			NameDE:    nameDE,
+			NameEN:    nameEN,
+			Firm:      r.FormValue("firm"),
+			CreatedBy: uid.String(),
+		},
+		docforge.TemplateVersionInput{
+			CarrierBytes: carrier,
+			Slots:        view.Slots,
+			CreatedBy:    uid.String(),
+		})
+	if err != nil {
+		writeTemplateError(w, err)
+		return
+	}
+	writeJSON(w, http.StatusCreated, authoringViewJSON{
+		Template:    metaJSON(tmpl.TemplateMeta),
+		PreviewHTML: view.PreviewHTML,
+		Slots:       slotsJSON(tmpl.Slots),
+	})
+}
+
+// handleGetTemplateAuthoring backs GET /api/admin/templates/{id} — the
+// authoring view: current carrier rendered run-addressable + its slots.
+func handleGetTemplateAuthoring(w http.ResponseWriter, r *http.Request) {
+	if !requireTemplateStore(w) {
+		return
+	}
+	if _, ok := requireUser(w, r); !ok {
+		return
+	}
+	tmpl, err := dbSvc.templateStore.Get(r.Context(), r.PathValue("id"))
+	if err != nil {
+		writeTemplateError(w, err)
+		return
+	}
+	view, err := docx.ImportForAuthoring(tmpl.CarrierBytes)
+	if err != nil {
+		writeJSON(w, http.StatusInternalServerError, map[string]string{"error": "stored carrier failed to parse: " + err.Error()})
+		return
+	}
+	writeJSON(w, http.StatusOK, authoringViewJSON{
+		Template:    metaJSON(tmpl.TemplateMeta),
+		PreviewHTML: view.PreviewHTML,
+		Slots:       slotsJSON(view.Slots),
+	})
+}
+
+type placeSlotInput struct {
+	RunIndex     int    `json:"run_index"`
+	SelectedText string `json:"selected_text"`
+	SlotKey      string `json:"slot_key"`
+}
+
+// handlePlaceTemplateSlot backs POST /api/admin/templates/{id}/slots —
+// inject a slot at the selection and persist as a new version.
+func handlePlaceTemplateSlot(w http.ResponseWriter, r *http.Request) {
+	if !requireTemplateStore(w) {
+		return
+	}
+	uid, ok := requireUser(w, r)
+	if !ok {
+		return
+	}
+	var in placeSlotInput
+	if err := json.NewDecoder(r.Body).Decode(&in); err != nil {
+		writeJSON(w, http.StatusBadRequest, map[string]string{"error": "invalid JSON body"})
+		return
+	}
+	id := r.PathValue("id")
+	tmpl, err := dbSvc.templateStore.Get(r.Context(), id)
+	if err != nil {
+		writeTemplateError(w, err)
+		return
+	}
+
+	newCarrier, err := docx.InjectSlot(tmpl.CarrierBytes, in.RunIndex, in.SelectedText, in.SlotKey)
+	if err != nil {
+		// Injection failures are client-fixable (bad selection / key).
+		writeJSON(w, http.StatusBadRequest, map[string]string{"error": err.Error()})
+		return
+	}
+	// Re-detect slots from the new carrier so template_slots mirrors the
+	// carrier's actual {{tokens}} (single source of truth).
+	newView, err := docx.ImportForAuthoring(newCarrier)
+	if err != nil {
+		writeJSON(w, http.StatusInternalServerError, map[string]string{"error": fmt.Sprintf("post-inject parse: %v", err)})
+		return
+	}
+	updated, err := dbSvc.templateStore.AddVersion(r.Context(), id,
+		docforge.TemplateVersionInput{
+			CarrierBytes: newCarrier,
+			Stylemap:     tmpl.Stylemap,
+			Slots:        newView.Slots,
+			CreatedBy:    uid.String(),
+		})
+	if err != nil {
+		writeTemplateError(w, err)
+		return
+	}
+	writeJSON(w, http.StatusOK, authoringViewJSON{
+		Template:    metaJSON(updated.TemplateMeta),
+		PreviewHTML: newView.PreviewHTML,
+		Slots:       slotsJSON(updated.Slots),
+	})
+}

pkg/docforge/docx/authoring.go

@@ -0,0 +1,172 @@
+package docx
+
+// Authoring support — the .docx side of the docforge authoring surface
+// (t-paliad-349 slice 6). Two operations back the "upload a base .docx →
+// place variable slots" flow:
+//
+//   ImportForAuthoring — parse an uploaded .docx into a run-addressable
+//     preview (one <span data-run="N"> per <w:t>, in document order) plus
+//     the slots already present in the carrier.
+//   InjectSlot — replace a selected piece of text inside run N with a
+//     {{slot_key}} placeholder, returning the new carrier bytes. The
+//     placeholder is the sentinel that locates the slot (PRD §5 lean) and
+//     the same token the generation-time renderer substitutes.
+//
+// Both walk runs in the same order (paragraphs, then <w:t> within), so the
+// data-run indices the preview emits address exactly the runs InjectSlot
+// targets. Injection keys on the selected text
+// (not a byte/UTF-16 offset) so umlauts in German prose can't desync the
+// client's selection from the server's slice.
+//
+// v1 scope (PRD §2.1): text-level slots inside body paragraphs. A run is a
+// <w:t> within a <w:p>; selections spanning runs or sitting in
+// headers/footers/tables are out of scope and surface as an error the UI
+// turns into "select within a single text span".
+
+import (
+	"bytes"
+	"fmt"
+	"strconv"
+	"strings"
+
+	"mgit.msbls.de/m/paliad/pkg/docforge"
+)
+
+// AuthoringView is the parsed, run-addressable form of an uploaded
+// template, ready for the authoring editor.
+type AuthoringView struct {
+	// PreviewHTML is the body rendered as paragraphs of run spans:
+	// <p>…<span class="docforge-run" data-run="N">text</span>…</p>.
+	// The client attaches selection handling to the run spans; data-run
+	// is the index InjectSlot expects.
+	PreviewHTML string
+	// Slots are the {{placeholder}} tokens already present in the
+	// carrier (so re-opening a saved template shows its slots).
+	Slots []docforge.TemplateSlot
+}
+
+// ImportForAuthoring parses carrierBytes (any .docx/.dotm/...) into an
+// AuthoringView. Runs the .dotm→.docx pre-pass so macro templates import
+// cleanly.
+func ImportForAuthoring(carrierBytes []byte) (*AuthoringView, error) {
+	clean, err := ConvertDotmToDocx(carrierBytes)
+	if err != nil {
+		return nil, fmt.Errorf("authoring import: convert: %w", err)
+	}
+	documentXML, _, err := splitBaseZip(clean)
+	if err != nil {
+		return nil, fmt.Errorf("authoring import: %w", err)
+	}
+	return &AuthoringView{
+		PreviewHTML: authoringPreviewHTML(documentXML),
+		Slots:       detectSlots(documentXML),
+	}, nil
+}
+
+// authoringPreviewHTML renders the body as run-addressable HTML. One <p>
+// per <w:p>; one <span class="docforge-run" data-run="N"> per <w:t>, with
+// the decoded run text HTML-escaped. N is the global run index in
+// document-then-paragraph order — the same order InjectSlot walks.
+func authoringPreviewHTML(documentXML []byte) string {
+	var out bytes.Buffer
+	runIdx := 0
+	paras := wParagraphRegex.FindAll(documentXML, -1)
+	for _, para := range paras {
+		out.WriteString("<p>")
+		for _, m := range wTextNodeRegex.FindAllSubmatch(para, -1) {
+			text := xmlDecode(string(m[2]))
+			out.WriteString(`<span class="docforge-run" data-run="`)
+			out.WriteString(strconv.Itoa(runIdx))
+			out.WriteString(`">`)
+			out.WriteString(htmlEscape(text))
+			out.WriteString(`</span>`)
+			runIdx++
+		}
+		out.WriteString("</p>\n")
+	}
+	if out.Len() == 0 {
+		return "<p></p>"
+	}
+	return out.String()
+}
+
+// detectSlots returns the distinct {{placeholder}} tokens present in the
+// document body, in first-appearance order.
+func detectSlots(documentXML []byte) []docforge.TemplateSlot {
+	seen := map[string]bool{}
+	var slots []docforge.TemplateSlot
+	// Match against decoded text so a placeholder split by an entity is
+	// still found the same way the renderer would substitute it.
+	for _, m := range wTextNodeRegex.FindAllSubmatch(documentXML, -1) {
+		text := xmlDecode(string(m[2]))
+		for _, pm := range placeholderRegex.FindAllStringSubmatch(text, -1) {
+			key := pm[1]
+			if seen[key] {
+				continue
+			}
+			seen[key] = true
+			slots = append(slots, docforge.TemplateSlot{
+				Key:        key,
+				Anchor:     "{{" + key + "}}",
+				OrderIndex: len(slots),
+			})
+		}
+	}
+	return slots
+}
+
+// InjectSlot replaces the first occurrence of selectedText inside run
+// runIndex with a {{slotKey}} placeholder and returns the new carrier
+// bytes. Errors when the run is out of range or selectedText isn't found
+// in that run (a render/selection desync, or a cross-run selection).
+func InjectSlot(carrierBytes []byte, runIndex int, selectedText, slotKey string) ([]byte, error) {
+	if selectedText == "" {
+		return nil, fmt.Errorf("authoring inject: empty selection")
+	}
+	if !placeholderRegex.MatchString("{{" + slotKey + "}}") {
+		return nil, fmt.Errorf("authoring inject: invalid slot key %q", slotKey)
+	}
+	clean, err := ConvertDotmToDocx(carrierBytes)
+	if err != nil {
+		return nil, fmt.Errorf("authoring inject: convert: %w", err)
+	}
+	documentXML, parts, err := splitBaseZip(clean)
+	if err != nil {
+		return nil, fmt.Errorf("authoring inject: %w", err)
+	}
+
+	runIdx := 0
+	injected := false
+	newDoc := wParagraphRegex.ReplaceAllFunc(documentXML, func(para []byte) []byte {
+		return wTextNodeRegex.ReplaceAllFunc(para, func(tnode []byte) []byte {
+			idx := runIdx
+			runIdx++
+			if injected || idx != runIndex {
+				return tnode
+			}
+			sub := wTextNodeRegex.FindSubmatch(tnode)
+			attrs := string(sub[1])
+			content := xmlDecode(string(sub[2]))
+			before, after, found := strings.Cut(content, selectedText)
+			if !found {
+				return tnode // not found here — reported after the walk
+			}
+			newContent := before + "{{" + slotKey + "}}" + after
+			if !strings.Contains(attrs, "xml:space") &&
+				(strings.HasPrefix(newContent, " ") || strings.HasSuffix(newContent, " ")) {
+				attrs += ` xml:space="preserve"`
+			}
+			injected = true
+			return []byte(`<w:t` + attrs + `>` + xmlEncode(newContent) + `</w:t>`)
+		})
+	})
+	if !injected {
+		return nil, fmt.Errorf("authoring inject: selection %q not found in run %d", selectedText, runIndex)
+	}
+
+	repacked, err := repackBaseZip(parts, newDoc)
+	if err != nil {
+		return nil, fmt.Errorf("authoring inject: %w", err)
+	}
+	return repacked, nil
+}

pkg/docforge/docx/authoring_test.go

@@ -0,0 +1,111 @@
+package docx
+
+import (
+	"strings"
+	"testing"
+)
+
+// docBody wraps a <w:body> inner string into a full document.xml.
+func docBody(inner string) string {
+	return `<?xml version="1.0" encoding="UTF-8" standalone="yes"?>` +
+		`<w:document xmlns:w="http://schemas.openxmlformats.org/wordprocessingml/2006/main">` +
+		`<w:body>` + inner + `</w:body></w:document>`
+}
+
+func TestImportForAuthoring_PreviewIsRunAddressable(t *testing.T) {
+	body := docBody(
+		`<w:p><w:r><w:t>Az. 4c O 12/23</w:t></w:r></w:p>` +
+			`<w:p><w:r><w:t>Klägerin</w:t></w:r><w:r><w:t xml:space="preserve"> GmbH</w:t></w:r></w:p>`)
+	view, err := ImportForAuthoring(minimalMergeDOCX(t, body))
+	if err != nil {
+		t.Fatalf("ImportForAuthoring: %v", err)
+	}
+	// Three <w:t> → three run spans, indexed 0,1,2 in document order.
+	for i, want := range []string{`data-run="0"`, `data-run="1"`, `data-run="2"`} {
+		if !strings.Contains(view.PreviewHTML, want) {
+			t.Errorf("preview missing %s (run %d); html=%s", want, i, view.PreviewHTML)
+		}
+	}
+	if !strings.Contains(view.PreviewHTML, "Az. 4c O 12/23") {
+		t.Errorf("preview missing run text; html=%s", view.PreviewHTML)
+	}
+	// Two paragraphs.
+	if n := strings.Count(view.PreviewHTML, "<p>"); n != 2 {
+		t.Errorf("paragraph count = %d; want 2", n)
+	}
+	if len(view.Slots) != 0 {
+		t.Errorf("fresh doc should have no slots; got %v", view.Slots)
+	}
+}
+
+func TestImportForAuthoring_DetectsExistingSlots(t *testing.T) {
+	body := docBody(`<w:p><w:r><w:t>Az. {{project.case_number}} vor {{project.court}}</w:t></w:r></w:p>`)
+	view, err := ImportForAuthoring(minimalMergeDOCX(t, body))
+	if err != nil {
+		t.Fatalf("ImportForAuthoring: %v", err)
+	}
+	if len(view.Slots) != 2 {
+		t.Fatalf("slots = %d; want 2 (%v)", len(view.Slots), view.Slots)
+	}
+	if view.Slots[0].Key != "project.case_number" || view.Slots[0].Anchor != "{{project.case_number}}" {
+		t.Errorf("slot[0] = %+v; want project.case_number", view.Slots[0])
+	}
+	if view.Slots[1].Key != "project.court" {
+		t.Errorf("slot[1].Key = %q; want project.court", view.Slots[1].Key)
+	}
+}
+
+func TestInjectSlot_ReplacesSelectionWithPlaceholder(t *testing.T) {
+	body := docBody(`<w:p><w:r><w:t>Az. 4c O 12/23 vor dem LG</w:t></w:r></w:p>`)
+	out, err := InjectSlot(minimalMergeDOCX(t, body), 0, "4c O 12/23", "project.case_number")
+	if err != nil {
+		t.Fatalf("InjectSlot: %v", err)
+	}
+	doc := readMergeDocumentXML(t, out)
+	if !strings.Contains(doc, "Az. {{project.case_number}} vor dem LG") {
+		t.Errorf("injected doc wrong; got %s", doc)
+	}
+	// Round-trips: re-importing finds the new slot.
+	view, err := ImportForAuthoring(out)
+	if err != nil {
+		t.Fatalf("re-import: %v", err)
+	}
+	if len(view.Slots) != 1 || view.Slots[0].Key != "project.case_number" {
+		t.Errorf("re-imported slots = %v; want [project.case_number]", view.Slots)
+	}
+}
+
+func TestInjectSlot_TargetsTheNamedRun(t *testing.T) {
+	// "GmbH" appears in run 1 only; "Müller" (with umlaut) in run 0.
+	body := docBody(
+		`<w:p><w:r><w:t>Müller</w:t></w:r><w:r><w:t xml:space="preserve"> GmbH</w:t></w:r></w:p>`)
+	out, err := InjectSlot(minimalMergeDOCX(t, body), 0, "Müller", "parties.claimant.name")
+	if err != nil {
+		t.Fatalf("InjectSlot: %v", err)
+	}
+	doc := readMergeDocumentXML(t, out)
+	if !strings.Contains(doc, "{{parties.claimant.name}}") {
+		t.Errorf("umlaut selection not replaced; got %s", doc)
+	}
+	if !strings.Contains(doc, " GmbH") {
+		t.Errorf("run 1 should be untouched; got %s", doc)
+	}
+}
+
+func TestInjectSlot_ErrorsWhenSelectionNotInRun(t *testing.T) {
+	body := docBody(`<w:p><w:r><w:t>Hello</w:t></w:r></w:p>`)
+	if _, err := InjectSlot(minimalMergeDOCX(t, body), 0, "Goodbye", "firm.name"); err == nil {
+		t.Error("expected error when selection absent from run; got nil")
+	}
+	// Out-of-range run index.
+	if _, err := InjectSlot(minimalMergeDOCX(t, body), 9, "Hello", "firm.name"); err == nil {
+		t.Error("expected error for out-of-range run index; got nil")
+	}
+}
+
+func TestInjectSlot_RejectsInvalidSlotKey(t *testing.T) {
+	body := docBody(`<w:p><w:r><w:t>Hello</w:t></w:r></w:p>`)
+	if _, err := InjectSlot(minimalMergeDOCX(t, body), 0, "Hello", "9bad-key!"); err == nil {
+		t.Error("expected error for invalid slot key; got nil")
+	}
+}