docs: sent tracking in the rules, parity and test records (P4b S5)

rules.md B-27 lists `documents_v2`, the one feature S4 to S7 share
(D-52), including `invoice.sent`; receipt-store.md lists the event;
parity.md gains the sent-tracking row (done: implemented, tested, and
golden-covered by the trial balance of the fixture book around a send);
testing.md records the tests and what P12 must mutate, and names the
two attention predicates as deferred with step 4 until U0b lands.

docs/parity.md

@@ -45,6 +45,7 @@ No other statuses.
 | 1099 vendor tracking + year-end worksheet | Vendors → Track payments for 1099; 1099 report | partial | hand-verified fixture (bill payments, card exclusion, reversal, year boundary); no golden file yet |
 | Prepaid expense + deferred revenue amortization | Amortization schedules (Xero/QBO add-ons) | partial | hand-verified fixture, to the cent; no golden file yet |
 | Automated cross-implementation diff harness (GnuCash first) | — (our `xtask oracle`) | todo | roadmap phase 3 |
+| Invoice sent tracking (who, how, to whom, when, original or reminder, the channel's reference) | Business → Invoices (Xero's "Sent"; QBO's email) | done | P4b S5; records, never sends (A-4); a send changes no figure; `invoice.sent` under `documents_v2` (D-52) |
 
 Workflow/UI parity (QuickBooks/Xero reference) gets its own catalog when the
 egui phase starts; semantics come first.
@@ -104,3 +105,14 @@ door on loopback for Caddy or a tunnel. `crates/ledger-cli/tests/two_user.rs`
 proves the account boundary and the move's head in CI
 (`.github/workflows/two-user.yml`); the recipe is `deploy/README.md`.
 The cutover rule in `docs/capability-parity.md` is unchanged.
+
+### P4b S5: sent tracking (2026-10-27)
+
+The catalog gains one row: an invoice's recorded sends. The books never
+send (A-4): `books.mark_sent` records who sent an invoice, how, to whom,
+when, whether it was the original or a reminder, and the channel's own
+reference, for an owner or a delegate such as an agent. The record is
+`invoice.sent`, under `documents_v2` (D-52), and it moves no figure, so
+the A/R and A/P rows' figures are unchanged. The floor never decreases:
+the row is `done`, tested by `sends_replay_and_project`,
+`a_send_changes_no_figure` and `mark_sent_records_who_and_how`.

docs/receipt-store.md

@@ -58,8 +58,10 @@ apply is safe — on startup the applier replays every journal line with
 - `ts`: UTC, RFC 3339. Recorded, never trusted for ordering (`seq` orders).
 - `type`: `account.added`, `entry.posted`, `entry.reversed`, `invoice.created`,
   `bill.created`, `receipt.attached`, `receipt.linked`, `receipt.unlinked`,
-  `document.filed`, `attachment.withdrawn` (plus the A/R, A/P, asset,
-  period, payroll, and class events listed on `JournalLine`).
+  `document.filed`, `attachment.withdrawn`, `invoice.sent` (a recorded
+  send: a document's record, never a ledger line or a figure; P4b S5)
+  (plus the A/R, A/P, asset, period, payroll, and class events listed on
+  `JournalLine`).
 - `payload`: the full domain facts (account fields, entry with lines, blob
   sha, ...). Everything the applier needs; nothing it must look up elsewhere.
   An `invoice.created` or `bill.created` written after the `documents_v2`

docs/spec/rules.md

@@ -1744,8 +1744,11 @@ which an earlier version refuses (S4.2); a `party.updated` with an email
 or a default terms fact (S4.2); an `invoice.created` or `bill.created`
 carrying a number, terms, a bill-to or seller snapshot, a customer
 reference or memo, a vendor reference, a receipt date or a duplicate's
-reason, or a line naming its account, quantity or unit price (S4.3); and
-S5 to S7's sends, settlements and write-offs. An older version would
+reason, or a line naming its account, quantity or unit price (S4.3);
+S5's `invoice.sent` (who sent an invoice, how, to whom and when: a record
+that moves no figure); S6's payments with `line`, `discount`,
+`discount_line`, `discount_reason`, `fee` or `fee_line`; and S7's
+`invoice.written_off`. An older version would
 restore the document without them silently: every invoice line would post
 to the revenue role and every bill line to general expenses, and every new
 event type would be refused. A command asks for

docs/testing.md

@@ -3050,3 +3050,54 @@ and `BooksServer::new`'s copy (a dropped field must fail
 `isolation_label_is_enforced_under_the_unit`); the host's `server_flags`
 extension and `parse_args`' passthrough of `--isolation` and its optional
 `--http` value.
+
+## P4b S5: sent tracking (2026-10-27)
+
+The books record that an invoice went out; they never send it (A-4). A
+send is `invoice.sent`, under `documents_v2` (D-52), and moves no figure:
+`Ledger::mark_sent` pushes a `Sent` onto the invoice, the store journals
+one line and no entry, replay restores it and the projection keeps it in
+`schema` v17's `invoice_sends` (S4.3 took 16).
+
+- **`ledger-store` `tests/arap_standing.rs`:** `mark_sent_waits_for_documents_v2`
+  (books with no features: refused, nothing journaled; after `upgrade`,
+  taken, and the reopen equals what was live), `sends_replay_and_project`
+  (two sends: the journal's `invoice.sent` carries the whole record in
+  order, `verify` passes, the reopened invoice holds both),
+  `a_send_changes_no_figure` (on the `p4-arap-before` fixture: the report
+  snapshot, the invoice's `DocState` and every derived cache are equal
+  before and after), `mark_sent_on_void_refused` (`DocumentVoid`,
+  nothing journaled; a send dated before the void is taken).
+- **`ledger-store` `tests/arap_props.rs`:** `status_is_a_function_of_journal_and_date`
+  gains `Op::Sent` (random sends on invoices, skipped on bills): every
+  figure, the control check and both agings still agree across live,
+  replay and snapshot.
+- **`ledger-store` `tests/format.rs`:** `an_older_version_stops_at_invoice_sent`
+  (`invoice.sent` is this version's, a reader without `documents_v2` waits,
+  and the books declare the feature before the first send line).
+- **8.0.6:** `books_written_under_older_rules_still_open` hand-writes an
+  `invoice.sent` and still opens; the fixture `old-books/p4_s5_before`
+  was written by eeee9658 (the revision before this unit) and opens to
+  the same figures; `books_p2_served_cut_over_whole` refuses a send before
+  consent and takes it after.
+- **`ledger-cli` `tests/documents.rs`:** `mark_sent_records_who_and_how`
+  (two sends over the wire: the token's name, email and original by
+  default, then a reminder with a message id; `books.documents` shows
+  `last_sent`, `books.document` both sends, and the invoice still owes its
+  total).
+- **`ledger-mcp/src/handbook.rs`:** the new `invoices-and-bills` section
+  renders, and its id is unique (the existing handbook tests).
+
+**For P12 (mutation targets):** `Ledger::mark_sent`'s refusals (unknown
+invoice, a send dated before it, `DocumentVoid`, empty `to`, and each of
+the three `check_text` calls; the note's check is stricter than the plan's
+list, to keep a full TIN out of the journal); `SentVia::parse`'s arms and
+its `other:` prefix; `SendKind::parse`'s two arms; `sent_via`'s arms and
+its empty fallback; `send_kind`'s error arm; the handler's `kind` default
+(`original` when `sends` is empty, `reminder` after), its `to` fallback
+(bill-to, then party, then refused) and its `by` fallback; `invoice_id`'s
+`invoice:` strip; `last_sent`'s `max`; and the replay reader's
+`newer_content` arms for an unknown channel or kind. The two attention
+predicates ("invoice never sent", "overdue invoice not reminded") and
+their day comparisons are deferred with the unit's step 4 until U0b
+lands, and are named here when they do.