Old rules for older accounts, a rules date per account, and a firm cap

When the master changes an account type with "New accounts only", it now
serves the type's old rules as kept rule sets (firm.keptAccountRules), each
for accounts dated inside [openedAt, closedAt). This build applies them:

- getAccountConfig, the one rules lookup trading reads, puts a kept set's
  rule fields over the live type when the account's rules date falls in
  its window. Id, label, prefix, size and the projection fields stay the
  live type's, so every report still names the live type.
- account_assignments gains rules_date and rules_date_manual. A new row is
  dated when the machine first sees the account, on the master's clock
  when this one runs behind and never before the catalog's last change.
  Auto dates come down to the broker's evidence: the end of the first fund
  day in Chicago, or a DXtrade registration instant. Evidence is applied
  before an account's first trade. Rows from before the migration get its
  time; unpinning keeps the row and its date. Backups carry both columns.
- An account on a kept set stays on its type while its prefix and cached
  size still match, so a tie-break flip can't move it off its old rules.
- Kept entries parse through the same normalizer as live types (now
  normalizeAccountType in lib/kept-rules.ts); a malformed one rejects the
  sync like a malformed type. The cached catalog records the parser that
  stored it, and a cache from an older parser is fetched in full rather
  than trusted with ?since= (this also brings in maxConcurrentAccounts).
- Reports add keptRuleIds per firm and live counts per kept set per type.
- The dashboard row and the account page show the rules date next to the
  account name, with an "old rules" chip saying what differs. Clicking
  the date edits it inline (PUT /api/accounts/:id/rules-date), previewing
  which rules the date lands on.

Also: the master's per-firm cap on accounts traded at once
(maxConcurrentAccounts), applied on top of the machine's own max
concurrent when a batch is drawn and in copy trading.

Co-Authored-By: Claude Opus 5.5 <noreply@anthropic.com>

lib/master-protocol.ts

@@ -81,6 +81,10 @@ export interface AccountTypeStats {
             stage: number; drain?: boolean;
         }[];
     }[];
+    /** Live accounts of this slice on each kept rule set — the slice itself
+     *  stays keyed by the live account type, whose id is the only one ever
+     *  reported as an accountTypeId. Optional. */
+    keptRules?: { id: string; accounts: number }[];
 }
 
 export interface FirmStats {
@@ -139,6 +143,10 @@ export interface FirmStats {
     /** The catalog firm's uuid (statusVersion builds), so the master needn't
      *  resolve the name. Optional. */
     firmId?: string;
+    /** Kept rule set ids this machine has loaded for the firm. Present (even
+     *  []) = this build applies kept rules and its cached catalog was parsed
+     *  by a parser that understands them. Absent = old build or stale cache. */
+    keptRuleIds?: string[];
     /** ISO time the firm's last good sync finished (statusVersion builds), sent
      *  once synced. The statuses count only while it is recent. Optional. */
     syncedAt?: string;
@@ -381,6 +389,22 @@ export interface CatalogAccountType {
     updatedAt: string;
 }
 
+/** Old rules an account type keeps for its accounts whose rules date is
+ *  inside [openedAt, closedAt) — set when the owner changes the type's rules
+ *  for new accounts only. Built as: live type X's fields, overwritten by the
+ *  snapshot's RULE fields, plus these. Never an account type itself: nothing
+ *  is pinned or reported by its id as an accountTypeId (lib/kept-rules.ts). */
+export interface KeptAccountRules extends CatalogAccountType {
+    /** This kept set's own uuid — never a live account type id. */
+    id: string;
+    /** The live account type id (X). */
+    keptFrom: string;
+    /** ISO; inclusive lower bound on the rules date; null = none. */
+    openedAt: string | null;
+    /** ISO; exclusive upper bound. */
+    closedAt: string;
+}
+
 /** Where a firm's accounts trade. A build only knows the platforms listed
  *  here; the catalog sync skips a firm on any other rather than guess. */
 export const FIRM_PLATFORMS = ['tradovate', 'topstepx', 'dxtrade'] as const;
@@ -421,10 +445,17 @@ export interface CatalogFirm {
     /** The firm's website ('' = none; absent from older masters). The master
      *  matches the extension's tab against it to find a person's 2FA code. */
     siteUrl?: string;
+    /** The most of the firm's accounts this machine trades at once, on top of
+     *  its own max_concurrent_accounts (0 = no firm cap; absent from older
+     *  masters). */
+    maxConcurrentAccounts?: number;
     /** Older masters' way to exclude roots; newer ones derive it from
      *  `instruments`. */
     bannedSymbols: string[];
     accountTypes: CatalogAccountType[];
+    /** Old rule sets the firm's account types keep for older accounts.
+     *  Optional; old builds drop it. */
+    keptAccountRules?: KeptAccountRules[];
     /** DXTrade REST base, e.g. https://dx.tradeify247.co/dxsca-web ('' otherwise). */
     serverUrl?: string;
     /** DXTrade login domain ('' = 'default'). */
@@ -458,6 +489,11 @@ export interface FirmCatalogPayload {
     firms: CatalogFirm[];
     /** Absent from a master from before its Settings page. */
     trading?: CatalogTradingSettings;
+    /** Instance-local, never sent by the master: the catalog parser version
+     *  (lib/firm-catalog.ts CATALOG_PARSER_VERSION) that produced a cached
+     *  payload. An older parser dropped fields it didn't know, so a cache
+     *  without it, or below the current one, isn't trusted to hold them. */
+    parser?: number;
 }
 
 export interface FirmCatalogUnchanged {