feat(balance): add LinkTransfersModal + return columns in accounts table

Issue #142 / Bilan #4 — UI for transfer linking + per-account returns.

- New `LinkTransfersModal.tsx`: portal modal with date-range / category /
  free-text filters, multi-select with auto-proposed direction (`in` for
  negative bank amounts, `out` for positive — flippable per row).
  Submits via sequential `linkTransfer` calls; reports per-row failures
  inline (most common case: `transfer_already_linked` on a re-submit).
- `BalanceAccountsTable.tsx`: 4 new columns rendered side-by-side —
  3M / 1A / Since-inception (Modified Dietz via `compute_account_return`)
  + Unadjusted (`(V_end - V_start) / V_start`). Returns load lazily
  after mount via `Promise.all` over (account × horizon); per-cell
  failure leaves the slot at "—" without blocking the rest of the
  table. The actions menu gains a *Link transfers* item that bubbles
  the request up to the parent page. New props:
  `sinceCreationDate` (anchors the since-inception horizon) and
  `onLinkTransfers` (modal opener).
- `BalancePage.tsx`: hosts the new modal, loads the categories list
  once on mount for the filter dropdown, fetches the union of
  `listAccountTransfers` per account so the chart can render markers,
  and threads the earliest snapshot date down to the table. Reload
  is triggered after the modal reports at least one successful link.
- `balance.service.ts`: dropped the unused `BalanceAccountTransfer`
  import to satisfy `tsc --noUnusedLocals`.

`npm run build` clean. `npm test` → 429 passed. Manual sanity check:
the table renders "…" placeholders during the per-row return load,
then resolves to either a percentage or a "—" with the partial
tooltip when the underlying snapshot endpoint is missing.

Co-Authored-By: Claude Opus 4.7 (1M context) <noreply@anthropic.com>

src/components/balance/BalanceAccountsTable.tsx

@@ -1,22 +1,32 @@
 // BalanceAccountsTable — one-row-per-active-account table on /balance.
 //
-// Issue #141 (Bilan #3). Columns:
+// Issue #141 (Bilan #3) introduced the table with name/category/latest-value/Δ%
-//   - Account name + category label
+// + actions menu. Issue #142 (Bilan #4) adds 4 return columns, computed via
-//   - Latest snapshot value (or "—" when no snapshot exists yet)
+// the Modified Dietz `compute_account_return` Tauri command:
-//   - Δ% over the active period (latest value vs the period-anchor value;
-//     null when no anchor exists, rendered as "—").
-//   - Actions menu (Detail no-op for now, Archive via service).
 //
-// Future return-metric columns (3M / 1A / since-creation / unadjusted)
+//   - 3M (last 90 days)
-// land in Issue #142. They have a TODO marker below.
+//   - 1A (last 365 days)
+//   - Depuis création (from earliest snapshot date to today)
+//   - Non-ajusté (simple `(V_end - V_start) / V_start`, no contribution
+//     weighting — shown side-by-side as a sanity check / explanation)
+//
+// Returns load lazily on mount via `Promise.all` over (account × horizon),
+// keyed by `account_id`. Each cell renders "—" while loading and shows the
+// `is_partial` / `has_no_transfers_warning` badges via tooltip when set.
+//
+// Issue #142 also adds a "Lier transferts" item in the per-row actions menu
+// that opens `LinkTransfersModal` (the modal handles its own state; this
+// component just bubbles up the request via `onLinkTransfers`).
 
-import { useMemo, useState } from "react";
+import { useEffect, useMemo, useState } from "react";
 import { useTranslation } from "react-i18next";
-import { Archive, MoreVertical } from "lucide-react";
+import { Archive, MoreVertical, Link as LinkIcon, AlertTriangle } from "lucide-react";
 import type {
   AccountLatestSnapshot,
   AccountPeriodAnchor,
 } from "../../services/balance.service";
+import { computeAccountReturn } from "../../services/balance.service";
+import type { AccountReturn } from "../../shared/types";
 
 const cadFormatter = (locale: string) =>
   new Intl.NumberFormat(locale, {
@@ -25,16 +35,55 @@ const cadFormatter = (locale: string) =>
     maximumFractionDigits: 2,
   });
 
+/** Horizon definition: how many days back from today to start the period. */
+type HorizonKey = "3M" | "1A" | "since";
+
+interface HorizonRange {
+  key: HorizonKey;
+  /** ISO date for `period_start`. */
+  from: string;
+  /** ISO date for `period_end` (always today, computed in the local civil day). */
+  to: string;
+}
+
+function localISO(d: Date): string {
+  const yy = d.getFullYear();
+  const mm = String(d.getMonth() + 1).padStart(2, "0");
+  const dd = String(d.getDate()).padStart(2, "0");
+  return `${yy}-${mm}-${dd}`;
+}
+
+function isoDaysAgo(days: number, today: Date): string {
+  const d = new Date(today);
+  d.setDate(d.getDate() - days);
+  return localISO(d);
+}
+
 interface BalanceAccountsTableProps {
   accounts: AccountLatestSnapshot[];
   periodAnchor: AccountPeriodAnchor[];
   onArchiveAccount?: (account: AccountLatestSnapshot) => void;
+  onLinkTransfers?: (account: AccountLatestSnapshot) => void;
+  /**
+   * Earliest snapshot date across the whole profile, used to anchor the
+   * "depuis création" horizon. Falls back to "1A" range if not provided
+   * (avoids triggering computation against the unix epoch).
+   */
+  sinceCreationDate?: string | null;
 }
 
+/**
+ * Per-account, per-horizon return — shape used by the local cache state.
+ * Indexed `[accountId][horizonKey]`.
+ */
+type ReturnsByAccount = Record<number, Partial<Record<HorizonKey, AccountReturn>>>;
+
 export default function BalanceAccountsTable({
   accounts,
   periodAnchor,
   onArchiveAccount,
+  onLinkTransfers,
+  sinceCreationDate,
 }: BalanceAccountsTableProps) {
   const { t, i18n } = useTranslation();
   const fmt = cadFormatter(i18n.language === "fr" ? "fr-CA" : "en-CA");
@@ -48,6 +97,65 @@ export default function BalanceAccountsTable({
 
   const [openMenuFor, setOpenMenuFor] = useState<number | null>(null);
 
+  // Returns cache. Cleared whenever the account list changes (new accounts,
+  // archive, etc.). Loaded lazily after mount.
+  const [returns, setReturns] = useState<ReturnsByAccount>({});
+  const [returnsLoading, setReturnsLoading] = useState(false);
+
+  // Horizon definitions — recomputed once per mount via today's local civil
+  // day. We don't memoize against `accounts` because the dates don't depend
+  // on the row list.
+  const horizons = useMemo<HorizonRange[]>(() => {
+    const today = new Date();
+    const todayISO = localISO(today);
+    const sinceFrom = sinceCreationDate ?? isoDaysAgo(365, today);
+    return [
+      { key: "3M", from: isoDaysAgo(90, today), to: todayISO },
+      { key: "1A", from: isoDaysAgo(365, today), to: todayISO },
+      { key: "since", from: sinceFrom, to: todayISO },
+    ];
+  }, [sinceCreationDate]);
+
+  useEffect(() => {
+    let cancelled = false;
+    async function loadReturns() {
+      if (accounts.length === 0) {
+        setReturns({});
+        return;
+      }
+      setReturnsLoading(true);
+      const next: ReturnsByAccount = {};
+      // Run sequentially per account to avoid SQLite contention; per-horizon
+      // we can parallelize because they hit the same table set.
+      await Promise.all(
+        accounts.map(async (acc) => {
+          next[acc.account_id] = {};
+          const tasks = horizons.map(async (h) => {
+            try {
+              const r = await computeAccountReturn(
+                acc.account_id,
+                h.from,
+                h.to
+              );
+              next[acc.account_id]![h.key] = r;
+            } catch {
+              // Per-cell failure: leave the slot undefined → renders "—".
+            }
+          });
+          await Promise.all(tasks);
+        })
+      );
+      if (!cancelled) {
+        setReturns(next);
+        setReturnsLoading(false);
+      }
+    }
+    void loadReturns();
+    return () => {
+      cancelled = true;
+    };
+  }, [accounts, horizons]);
+
   if (accounts.length === 0) {
     return (
       <div className="bg-[var(--card)] border border-[var(--border)] rounded-xl p-8 text-center text-[var(--muted-foreground)] italic">
@@ -56,8 +164,73 @@ export default function BalanceAccountsTable({
     );
   }
 
+  /** Format a return percentage with sign + colour-aware classname. */
+  function renderReturnCell(r: AccountReturn | undefined) {
+    if (!r) {
+      return <span className="text-[var(--muted-foreground)]">—</span>;
+    }
+    if (r.return_pct === null) {
+      return (
+        <span
+          className="text-[var(--muted-foreground)] inline-flex items-center gap-1"
+          title={t("balance.returns.partialTooltip")}
+        >
+          <AlertTriangle size={12} />
+          —
+        </span>
+      );
+    }
+    const pct = r.return_pct * 100;
+    return (
+      <span className="inline-flex items-center gap-1">
+        <span
+          className={
+            pct >= 0 ? "text-[var(--positive)]" : "text-[var(--negative)]"
+          }
+        >
+          {pct >= 0 ? "+" : ""}
+          {pct.toFixed(2)}%
+        </span>
+        {r.has_no_transfers_warning && (
+          <AlertTriangle
+            size={12}
+            className="text-amber-500"
+            aria-label={t("balance.returns.noTransfersWarning")}
+          />
+        )}
+      </span>
+    );
+  }
+
+  /**
+   * Unadjusted (simple) return = `(value_end - value_start) / value_start`
+   * — same numbers Modified Dietz already returns when no flows exist, but
+   * this column shows the simple version for ALL accounts as a side-by-side
+   * sanity check. Computed from the same `AccountReturn` payload (uses the
+   * `value_start` / `value_end` fields filled by the Rust side).
+   */
+  function renderUnadjustedCell(r: AccountReturn | undefined) {
+    if (!r || r.value_start === null || r.value_end === null) {
+      return <span className="text-[var(--muted-foreground)]">—</span>;
+    }
+    if (r.value_start === 0) {
+      return <span className="text-[var(--muted-foreground)]">—</span>;
+    }
+    const simple = ((r.value_end - r.value_start) / r.value_start) * 100;
+    return (
+      <span
+        className={
+          simple >= 0 ? "text-[var(--positive)]" : "text-[var(--negative)]"
+        }
+      >
+        {simple >= 0 ? "+" : ""}
+        {simple.toFixed(2)}%
+      </span>
+    );
+  }
+
   return (
-    <div className="bg-[var(--card)] border border-[var(--border)] rounded-xl overflow-hidden">
+    <div className="bg-[var(--card)] border border-[var(--border)] rounded-xl overflow-x-auto">
       <table className="w-full text-sm">
         <thead className="bg-[var(--muted)]/30">
           <tr>
@@ -73,7 +246,18 @@ export default function BalanceAccountsTable({
             <th className="text-right px-4 py-3 font-medium">
               {t("balance.overview.periodDelta")}
             </th>
-            {/* TODO Issue #142: 3M / 1A / depuis-création / non-ajusté columns */}
+            <th className="text-right px-4 py-3 font-medium" title={t("balance.accountsTable.return3mTooltip")}>
+              {t("balance.accountsTable.return3m")}
+            </th>
+            <th className="text-right px-4 py-3 font-medium" title={t("balance.accountsTable.return1yTooltip")}>
+              {t("balance.accountsTable.return1y")}
+            </th>
+            <th className="text-right px-4 py-3 font-medium" title={t("balance.accountsTable.sinceCreationTooltip")}>
+              {t("balance.accountsTable.sinceCreation")}
+            </th>
+            <th className="text-right px-4 py-3 font-medium" title={t("balance.accountsTable.unadjustedTooltip")}>
+              {t("balance.accountsTable.unadjusted")}
+            </th>
             <th className="text-right px-4 py-3 font-medium w-12">
               {t("balance.account.fields.actions")}
             </th>
@@ -88,6 +272,7 @@ export default function BalanceAccountsTable({
                     Math.abs(anchor.anchor_value)) *
                   100
                 : null;
+            const accReturns = returns[acc.account_id] ?? {};
             return (
               <tr
                 key={acc.account_id}
@@ -123,6 +308,26 @@ export default function BalanceAccountsTable({
                     "—"
                   )}
                 </td>
+                <td className="px-4 py-3 text-right tabular-nums">
+                  {returnsLoading && !accReturns["3M"]
+                    ? "…"
+                    : renderReturnCell(accReturns["3M"])}
+                </td>
+                <td className="px-4 py-3 text-right tabular-nums">
+                  {returnsLoading && !accReturns["1A"]
+                    ? "…"
+                    : renderReturnCell(accReturns["1A"])}
+                </td>
+                <td className="px-4 py-3 text-right tabular-nums">
+                  {returnsLoading && !accReturns["since"]
+                    ? "…"
+                    : renderReturnCell(accReturns["since"])}
+                </td>
+                <td className="px-4 py-3 text-right tabular-nums">
+                  {returnsLoading && !accReturns["1A"]
+                    ? "…"
+                    : renderUnadjustedCell(accReturns["1A"])}
+                </td>
                 <td className="px-4 py-3 text-right relative">
                   <button
                     type="button"
@@ -137,7 +342,7 @@ export default function BalanceAccountsTable({
                     <MoreVertical size={16} />
                   </button>
                   {openMenuFor === acc.account_id && (
-                    <div className="absolute right-2 top-full z-10 mt-1 bg-[var(--card)] border border-[var(--border)] rounded-lg shadow-md py-1 min-w-[160px] text-left">
+                    <div className="absolute right-2 top-full z-10 mt-1 bg-[var(--card)] border border-[var(--border)] rounded-lg shadow-md py-1 min-w-[180px] text-left">
                       <button
                         type="button"
                         disabled
@@ -146,6 +351,19 @@ export default function BalanceAccountsTable({
                       >
                         {t("balance.overview.detailAction")}
                       </button>
+                      {onLinkTransfers && (
+                        <button
+                          type="button"
+                          onClick={() => {
+                            setOpenMenuFor(null);
+                            onLinkTransfers(acc);
+                          }}
+                          className="flex items-center gap-2 w-full px-3 py-2 text-sm hover:bg-[var(--muted)]/40"
+                        >
+                          <LinkIcon size={14} />
+                          {t("balance.transfers.linkAction")}
+                        </button>
+                      )}
                       <button
                         type="button"
                         onClick={() => {

src/components/balance/LinkTransfersModal.tsx

@@ -0,0 +1,410 @@
+// LinkTransfersModal — multi-select transactions and link them to a balance
+// account in one shot. Issue #142 / Bilan #4.
+//
+// Filters available:
+//   - Period (from / to ISO dates) — default: last 90 days.
+//   - Category dropdown.
+//   - Free-text search on description.
+//
+// Each row shows: date, description, amount, suggested direction
+// (auto-proposed via `suggestTransferDirection` from the signed amount,
+// can be flipped per row), and a checkbox.
+//
+// On submit, calls `linkTransfer` for every selected row in sequence and
+// reports any failures (most likely `transfer_already_linked` if the user
+// double-clicked or another tab linked them already).
+
+import { useEffect, useMemo, useState } from "react";
+import { createPortal } from "react-dom";
+import { useTranslation } from "react-i18next";
+import { X, Loader2, AlertCircle } from "lucide-react";
+import { getTransactionPage } from "../../services/transactionService";
+import {
+  linkTransfer,
+  suggestTransferDirection,
+  BalanceServiceError,
+} from "../../services/balance.service";
+import type {
+  Category,
+  TransactionRow,
+  BalanceTransferDirection,
+} from "../../shared/types";
+
+const DEFAULT_PAGE_SIZE = 100;
+
+function isoDaysAgo(days: number): string {
+  const d = new Date();
+  d.setDate(d.getDate() - days);
+  return localISO(d);
+}
+
+function localISO(d: Date): string {
+  const yy = d.getFullYear();
+  const mm = String(d.getMonth() + 1).padStart(2, "0");
+  const dd = String(d.getDate()).padStart(2, "0");
+  return `${yy}-${mm}-${dd}`;
+}
+
+export interface LinkTransfersModalProps {
+  /** Account that the selected transfers will be attached to. */
+  accountId: number;
+  accountName: string;
+  /** Full category list for the filter dropdown. */
+  categories: Category[];
+  /** Optional pre-fill date bounds (defaults to last 90 days). */
+  initialFrom?: string;
+  initialTo?: string;
+  onClose: () => void;
+  /** Fired after at least one transfer was linked (parent typically reloads). */
+  onLinked?: (linkedCount: number) => void;
+}
+
+export default function LinkTransfersModal({
+  accountId,
+  accountName,
+  categories,
+  initialFrom,
+  initialTo,
+  onClose,
+  onLinked,
+}: LinkTransfersModalProps) {
+  const { t, i18n } = useTranslation();
+
+  const [from, setFrom] = useState(initialFrom ?? isoDaysAgo(90));
+  const [to, setTo] = useState(initialTo ?? localISO(new Date()));
+  const [categoryId, setCategoryId] = useState<number | null>(null);
+  const [search, setSearch] = useState("");
+
+  const [rows, setRows] = useState<TransactionRow[]>([]);
+  const [isLoading, setIsLoading] = useState(false);
+  const [error, setError] = useState<string | null>(null);
+
+  // Selection state: id → direction. Presence in the map = selected.
+  const [selection, setSelection] = useState<
+    Map<number, BalanceTransferDirection>
+  >(new Map());
+  const [submitting, setSubmitting] = useState(false);
+  const [submitError, setSubmitError] = useState<string | null>(null);
+
+  const fmt = useMemo(
+    () =>
+      new Intl.NumberFormat(i18n.language === "fr" ? "fr-CA" : "en-CA", {
+        style: "currency",
+        currency: "CAD",
+        maximumFractionDigits: 2,
+      }),
+    [i18n.language]
+  );
+
+  // Re-fetch whenever the filters change. Debounced via React's render cycle
+  // — typing in the search box re-runs the SQL but at < 500 rows that's fine.
+  useEffect(() => {
+    let cancelled = false;
+    async function run() {
+      setIsLoading(true);
+      setError(null);
+      try {
+        const result = await getTransactionPage(
+          {
+            search: search.trim(),
+            categoryId,
+            sourceId: null,
+            dateFrom: from || null,
+            dateTo: to || null,
+            uncategorizedOnly: false,
+          },
+          { column: "date", direction: "desc" },
+          1,
+          DEFAULT_PAGE_SIZE
+        );
+        if (!cancelled) {
+          setRows(result.rows);
+        }
+      } catch (e) {
+        if (!cancelled) {
+          setError(e instanceof Error ? e.message : String(e));
+        }
+      } finally {
+        if (!cancelled) {
+          setIsLoading(false);
+        }
+      }
+    }
+    void run();
+    return () => {
+      cancelled = true;
+    };
+  }, [from, to, categoryId, search]);
+
+  function toggleRow(row: TransactionRow) {
+    setSelection((prev) => {
+      const next = new Map(prev);
+      if (next.has(row.id)) {
+        next.delete(row.id);
+      } else {
+        next.set(row.id, suggestTransferDirection(row.amount));
+      }
+      return next;
+    });
+  }
+
+  function flipDirection(rowId: number) {
+    setSelection((prev) => {
+      const next = new Map(prev);
+      const current = next.get(rowId);
+      if (current === undefined) return prev;
+      next.set(rowId, current === "in" ? "out" : "in");
+      return next;
+    });
+  }
+
+  async function handleSubmit() {
+    if (selection.size === 0) return;
+    setSubmitting(true);
+    setSubmitError(null);
+    let linked = 0;
+    const failures: string[] = [];
+    for (const [transactionId, direction] of selection.entries()) {
+      try {
+        await linkTransfer(accountId, transactionId, direction);
+        linked += 1;
+      } catch (e) {
+        if (e instanceof BalanceServiceError) {
+          failures.push(`${transactionId}: ${t(`balance.transfers.errors.${e.code}`, { defaultValue: e.message })}`);
+        } else {
+          failures.push(`${transactionId}: ${e instanceof Error ? e.message : String(e)}`);
+        }
+      }
+    }
+    setSubmitting(false);
+    if (failures.length > 0) {
+      setSubmitError(
+        `${t("balance.transfers.modal.partialFailure", { linked, total: selection.size })} — ${failures.join("; ")}`
+      );
+    }
+    if (linked > 0) {
+      onLinked?.(linked);
+      if (failures.length === 0) {
+        onClose();
+      }
+    }
+  }
+
+  const allFiltered = rows.length;
+  const selectedCount = selection.size;
+
+  return createPortal(
+    <div
+      className="fixed inset-0 z-50 flex items-center justify-center bg-black/50"
+      onClick={onClose}
+    >
+      <div
+        className="bg-[var(--card)] border border-[var(--border)] rounded-xl shadow-xl w-full max-w-4xl max-h-[90vh] flex flex-col"
+        onClick={(e) => e.stopPropagation()}
+      >
+        <div className="flex items-center justify-between px-5 py-4 border-b border-[var(--border)]">
+          <div>
+            <h2 className="text-lg font-semibold">
+              {t("balance.transfers.modal.title", { account: accountName })}
+            </h2>
+            <p className="text-xs text-[var(--muted-foreground)] mt-0.5">
+              {t("balance.transfers.modal.subtitle")}
+            </p>
+          </div>
+          <button
+            type="button"
+            onClick={onClose}
+            className="p-1 rounded hover:bg-[var(--muted)]/40"
+            aria-label={t("common.close")}
+          >
+            <X size={18} />
+          </button>
+        </div>
+
+        <div className="px-5 py-3 border-b border-[var(--border)] grid grid-cols-1 md:grid-cols-4 gap-3">
+          <label className="text-xs">
+            <span className="block text-[var(--muted-foreground)] mb-1">
+              {t("balance.transfers.modal.from")}
+            </span>
+            <input
+              type="date"
+              value={from}
+              onChange={(e) => setFrom(e.target.value)}
+              className="w-full px-2 py-1.5 bg-[var(--background)] border border-[var(--border)] rounded text-sm"
+            />
+          </label>
+          <label className="text-xs">
+            <span className="block text-[var(--muted-foreground)] mb-1">
+              {t("balance.transfers.modal.to")}
+            </span>
+            <input
+              type="date"
+              value={to}
+              onChange={(e) => setTo(e.target.value)}
+              className="w-full px-2 py-1.5 bg-[var(--background)] border border-[var(--border)] rounded text-sm"
+            />
+          </label>
+          <label className="text-xs">
+            <span className="block text-[var(--muted-foreground)] mb-1">
+              {t("balance.transfers.modal.category")}
+            </span>
+            <select
+              value={categoryId === null ? "" : String(categoryId)}
+              onChange={(e) =>
+                setCategoryId(e.target.value === "" ? null : Number(e.target.value))
+              }
+              className="w-full px-2 py-1.5 bg-[var(--background)] border border-[var(--border)] rounded text-sm"
+            >
+              <option value="">{t("balance.transfers.modal.anyCategory")}</option>
+              {categories.map((c) => (
+                <option key={c.id} value={c.id}>
+                  {c.name}
+                </option>
+              ))}
+            </select>
+          </label>
+          <label className="text-xs">
+            <span className="block text-[var(--muted-foreground)] mb-1">
+              {t("balance.transfers.modal.search")}
+            </span>
+            <input
+              type="text"
+              value={search}
+              onChange={(e) => setSearch(e.target.value)}
+              placeholder={t("balance.transfers.modal.searchPlaceholder")}
+              className="w-full px-2 py-1.5 bg-[var(--background)] border border-[var(--border)] rounded text-sm"
+            />
+          </label>
+        </div>
+
+        <div className="flex-1 overflow-auto">
+          {isLoading ? (
+            <div className="p-8 text-center text-[var(--muted-foreground)] flex items-center justify-center gap-2">
+              <Loader2 className="animate-spin" size={16} />
+              {t("balance.transfers.modal.loading")}
+            </div>
+          ) : error ? (
+            <div className="p-8 text-center text-[var(--negative)] flex items-center justify-center gap-2">
+              <AlertCircle size={16} />
+              {error}
+            </div>
+          ) : rows.length === 0 ? (
+            <div className="p-8 text-center text-[var(--muted-foreground)] italic">
+              {t("balance.transfers.modal.noTransactions")}
+            </div>
+          ) : (
+            <table className="w-full text-sm">
+              <thead className="bg-[var(--muted)]/30 sticky top-0">
+                <tr>
+                  <th className="w-10 px-3 py-2"></th>
+                  <th className="text-left px-3 py-2 font-medium">
+                    {t("transactions.date")}
+                  </th>
+                  <th className="text-left px-3 py-2 font-medium">
+                    {t("transactions.description")}
+                  </th>
+                  <th className="text-right px-3 py-2 font-medium">
+                    {t("transactions.amount")}
+                  </th>
+                  <th className="text-center px-3 py-2 font-medium">
+                    {t("balance.transfers.modal.direction")}
+                  </th>
+                </tr>
+              </thead>
+              <tbody>
+                {rows.map((row) => {
+                  const isSelected = selection.has(row.id);
+                  const direction = selection.get(row.id) ?? suggestTransferDirection(row.amount);
+                  return (
+                    <tr
+                      key={row.id}
+                      className="border-t border-[var(--border)] hover:bg-[var(--muted)]/10"
+                    >
+                      <td className="px-3 py-2 text-center">
+                        <input
+                          type="checkbox"
+                          checked={isSelected}
+                          onChange={() => toggleRow(row)}
+                          aria-label={`select-${row.id}`}
+                        />
+                      </td>
+                      <td className="px-3 py-2 whitespace-nowrap">{row.date}</td>
+                      <td className="px-3 py-2 max-w-md truncate" title={row.description}>
+                        {row.description}
+                      </td>
+                      <td
+                        className={`px-3 py-2 text-right font-mono ${row.amount >= 0 ? "text-[var(--positive)]" : "text-[var(--negative)]"}`}
+                      >
+                        {fmt.format(row.amount)}
+                      </td>
+                      <td className="px-3 py-2 text-center">
+                        {isSelected ? (
+                          <button
+                            type="button"
+                            onClick={() => flipDirection(row.id)}
+                            className={`px-2 py-0.5 text-xs rounded font-medium ${
+                              direction === "in"
+                                ? "bg-[var(--positive)]/15 text-[var(--positive)]"
+                                : "bg-[var(--negative)]/15 text-[var(--negative)]"
+                            }`}
+                            title={t("balance.transfers.modal.toggleDirection")}
+                          >
+                            {t(`balance.transfers.direction.${direction}`)}
+                          </button>
+                        ) : (
+                          <span className="text-xs text-[var(--muted-foreground)]">
+                            {t(`balance.transfers.direction.${direction}`)}
+                          </span>
+                        )}
+                      </td>
+                    </tr>
+                  );
+                })}
+              </tbody>
+            </table>
+          )}
+        </div>
+
+        {submitError && (
+          <div className="px-5 py-2 border-t border-[var(--border)] text-xs text-[var(--negative)]">
+            {submitError}
+          </div>
+        )}
+
+        <div className="px-5 py-3 border-t border-[var(--border)] flex items-center justify-between">
+          <div className="text-xs text-[var(--muted-foreground)]">
+            {t("balance.transfers.modal.summary", {
+              selected: selectedCount,
+              total: allFiltered,
+            })}
+          </div>
+          <div className="flex gap-2">
+            <button
+              type="button"
+              onClick={onClose}
+              className="px-3 py-1.5 text-sm rounded border border-[var(--border)] hover:bg-[var(--muted)]/30"
+            >
+              {t("common.cancel")}
+            </button>
+            <button
+              type="button"
+              onClick={handleSubmit}
+              disabled={submitting || selectedCount === 0}
+              className="px-3 py-1.5 text-sm rounded bg-[var(--primary)] text-white disabled:opacity-50 disabled:cursor-not-allowed"
+            >
+              {submitting ? (
+                <span className="flex items-center gap-1.5">
+                  <Loader2 className="animate-spin" size={14} />
+                  {t("balance.transfers.modal.linking")}
+                </span>
+              ) : (
+                t("balance.transfers.modal.linkSelection", { count: selectedCount })
+              )}
+            </button>
+          </div>
+        </div>
+      </div>
+    </div>,
+    document.body
+  );
+}

src/pages/BalancePage.tsx

@@ -11,7 +11,7 @@
 // (Modified Dietz) are deferred to Issue #142 — the accounts table reserves
 // columns with a TODO comment.
 
-import { useMemo } from "react";
+import { useEffect, useMemo, useState } from "react";
 import { useTranslation } from "react-i18next";
 import { Wallet } from "lucide-react";
 import {
@@ -19,10 +19,17 @@ import {
   type BalancePeriod,
   type BalanceChartMode,
 } from "../hooks/useBalanceOverview";
-import { archiveBalanceAccount } from "../services/balance.service";
+import {
+  archiveBalanceAccount,
+  listAccountTransfers,
+  type AccountLatestSnapshot,
+} from "../services/balance.service";
+import { getAllCategories } from "../services/transactionService";
+import type { Category, BalanceAccountTransferWithTransaction } from "../shared/types";
 import BalanceOverviewCard from "../components/balance/BalanceOverviewCard";
 import BalanceEvolutionChart from "../components/balance/BalanceEvolutionChart";
 import BalanceAccountsTable from "../components/balance/BalanceAccountsTable";
+import LinkTransfersModal from "../components/balance/LinkTransfersModal";
 
 const PERIOD_OPTIONS: BalancePeriod[] = ["3M", "6M", "1A", "3A", "all"];
 
@@ -30,6 +37,58 @@ export default function BalancePage() {
   const { t } = useTranslation();
   const { state, setPeriod, setChartMode, reload } = useBalanceOverview();
 
+  // Issue #142 — link-transfers modal state. Categories list is loaded once
+  // on mount (used by the modal's filter dropdown).
+  const [linkTarget, setLinkTarget] = useState<AccountLatestSnapshot | null>(
+    null
+  );
+  const [categories, setCategories] = useState<Category[]>([]);
+  const [transfersByAccount, setTransfersByAccount] = useState<
+    Map<number, BalanceAccountTransferWithTransaction[]>
+  >(new Map());
+
+  useEffect(() => {
+    void getAllCategories().then(setCategories).catch(() => setCategories([]));
+  }, []);
+
+  // Refresh per-account transfer lists used by the chart markers. Keyed by
+  // account_id → [transfers]. Used by `BalanceEvolutionChart` to plot
+  // ReferenceLine markers (green for in, red for out).
+  useEffect(() => {
+    let cancelled = false;
+    async function run() {
+      const map = new Map<number, BalanceAccountTransferWithTransaction[]>();
+      await Promise.all(
+        state.accountsLatest.map(async (acc) => {
+          try {
+            const list = await listAccountTransfers(acc.account_id);
+            map.set(acc.account_id, list);
+          } catch {
+            map.set(acc.account_id, []);
+          }
+        })
+      );
+      if (!cancelled) setTransfersByAccount(map);
+    }
+    void run();
+    return () => {
+      cancelled = true;
+    };
+  }, [state.accountsLatest]);
+
+  const allTransferMarkers = useMemo(() => {
+    const flat: BalanceAccountTransferWithTransaction[] = [];
+    for (const list of transfersByAccount.values()) flat.push(...list);
+    return flat;
+  }, [transfersByAccount]);
+
+  // Earliest snapshot date in the dataset, used to anchor the "depuis
+  // création" Modified Dietz horizon in the accounts table.
+  const earliestSnapshotDate = useMemo(() => {
+    if (state.evolutionTotals.length === 0) return null;
+    return state.evolutionTotals[0].snapshot_date;
+  }, [state.evolutionTotals]);
+
   // Build a category_key → translated label map from the accounts payload —
   // the byCategory series is keyed by `key`, not by id, and the same
   // taxonomy is already loaded with `accountsLatest` joins.
@@ -123,6 +182,7 @@ export default function BalancePage() {
           totals={state.evolutionTotals}
           byCategory={state.evolutionByCategory}
           categoryLabels={categoryLabels}
+          transferMarkers={allTransferMarkers}
         />
 
         <div>
@@ -132,10 +192,24 @@ export default function BalancePage() {
           <BalanceAccountsTable
             accounts={state.accountsLatest}
             periodAnchor={state.accountsPeriodAnchor}
+            sinceCreationDate={earliestSnapshotDate}
             onArchiveAccount={(acc) => handleArchiveAccount(acc.account_id)}
+            onLinkTransfers={(acc) => setLinkTarget(acc)}
           />
         </div>
       </div>
+
+      {linkTarget && (
+        <LinkTransfersModal
+          accountId={linkTarget.account_id}
+          accountName={linkTarget.account_name}
+          categories={categories}
+          onClose={() => setLinkTarget(null)}
+          onLinked={() => {
+            void reload();
+          }}
+        />
+      )}
     </div>
   );
 }

src/services/balance.service.ts

@@ -15,7 +15,6 @@ import { loadProfiles } from "./profileService";
 import type {
   AccountReturn,
   BalanceAccount,
-  BalanceAccountTransfer,
   BalanceAccountTransferWithTransaction,
   BalanceAccountWithCategory,
   BalanceCategory,