feat(dimensions): PR9 cutover — cost_center/project become GENERATED columns, dual-write removed (#870)

The dual-write window ends (dev_docs/dimensions_implementation_plan.md PR9):
journal_entry_lines.cost_center/project are now GENERATED ALWAYS AS
(NULLIF(dimensions->>'1'/'6','')) STORED — divergence from the bag is
impossible by construction instead of by convention.

- migration 20260702230000: drift pre-flight (refuses cutover on
  inconsistent data; prod verified 0 drift across 593k rows), column swap
  (DROP metadata-only + one-rewrite ADD pair), and atomic redefinition of
  the two SQL writers — retag_line_dimensions (SET dimensions only) and
  bulk_book_transactions (INSERT names the bag only)
- TS writers stripped of the mirror spread: engine buildLineInserts
  (covers create/update/reversal), storno-service (reversal + correction),
  SIE import bulk insert, sandbox seed
- lineDimensionColumns() removed from dimension-resolver — nothing derives
  mirrors in TypeScript anymore; normalizeLineDimensions + the deprecated
  cost_center/project INPUT aliases stay (API contract, they normalize
  into the bag); JournalEntryLine ROW type keeps the fields (generated
  columns still SELECT)
- immutability carve-out unchanged BY DESIGN: its whole-row diff already
  subtracts dimensions/cost_center/project on both sides, which is exactly
  what makes it correct with generated columns (BEFORE-trigger NEW carries
  not-yet-recomputed mirror values)
- audited every reader (v1 journal-entries, MCP query_journal filters +
  group_by, rc-basis-gaps) — reads are untouched; no index, view, or
  constraint referenced the TEXT columns, so DROP COLUMN cascades nothing
- new pg suite: generated derivation, explicit-mirror-write rejection,
  draft-update recompute; existing retag/substrate/bulk-book suites
  updated to bag-only writes (their mirror assertions now exercise the
  generation expression)

Co-authored-by: Claude Fable 5 <noreply@anthropic.com>

tests/pg/bulk-book-dimensions.pg.test.ts

@@ -12,9 +12,9 @@ import { getPool, withUserContext } from '@/tests/pg/setup'
  * Covers 20260702201000_bulk_book_transactions_dimensions (dimensions PR7):
  *
  *   - p_new_entry lines may carry a dimensions bag {sie_dim_no: code}. The
- *     RPC stores it on journal_entry_lines.dimensions AND derives the
- *     dual-write mirror columns cost_center/project from keys '1'/'6'
- *     (lineDimensionColumns contract — mirrors never set independently).
+ *     RPC stores it on journal_entry_lines.dimensions; cost_center/project
+ *     derive from keys '1'/'6' (GENERATED columns since the PR9 cutover —
+ *     the mirror assertions below now exercise the generation expression).
  *   - Bag normalization mirrors DimensionsBagSchema: non-canonical keys
  *     (leading zeros, non-numeric) and blank values are dropped; values are
  *     trimmed.

tests/pg/dimension-retag.pg.test.ts

@@ -41,10 +41,10 @@ async function insertPostedTaggedEntry(params: {
   const dims = params.dimensions ?? {}
   const { rows } = await getPool().query<{ id: string }>(
     `INSERT INTO public.journal_entry_lines
-       (journal_entry_id, account_number, debit_amount, credit_amount, dimensions, cost_center, project)
-     VALUES ($1, '5010', 1000, 0, $2::jsonb, $3, $4)
+       (journal_entry_id, account_number, debit_amount, credit_amount, dimensions)
+     VALUES ($1, '5010', 1000, 0, $2::jsonb)
      RETURNING id`,
-    [entryId, JSON.stringify(dims), dims['1'] ?? null, dims['6'] ?? null],
+    [entryId, JSON.stringify(dims)],
   )
   await getPool().query(
     `INSERT INTO public.journal_entry_lines
@@ -207,12 +207,13 @@ describe('dimension retag carve-out (PR6)', () => {
       ).rejects.toThrow(/Cannot UPDATE lines of a posted journal entry/)
       await client.query('ROLLBACK')
 
-      // A pure dimension diff IS admitted under the GUC (the RPC's write shape).
+      // A pure dimension diff IS admitted under the GUC (the RPC's write
+      // shape). PR9: the bag alone — the generated mirrors recompute.
       await client.query('BEGIN')
       await client.query(`SELECT set_config('gnubok.allow_dimension_retag', 'true', true)`)
       await client.query(
         `UPDATE public.journal_entry_lines
-            SET dimensions = '{"6":"P001"}'::jsonb, project = 'P001'
+            SET dimensions = '{"6":"P001"}'::jsonb
           WHERE id = $1`,
         [lineId],
       )

tests/pg/dimensions-generated-cutover.pg.test.ts

@@ -0,0 +1,99 @@
+import { describe, expect, it } from 'vitest'
+import {
+  insertAuthUser,
+  insertCompany,
+  insertCompanyMember,
+  insertFiscalPeriod,
+  insertDraftJournalEntry,
+} from '@/tests/pg/fixtures'
+import { getPool } from '@/tests/pg/setup'
+
+/**
+ * Covers 20260702230000_dimensions_generated_column_cutover (dimensions PR9):
+ *
+ *   - cost_center/project are GENERATED ALWAYS AS (NULLIF(dimensions->>'1'/'6',''))
+ *     STORED — inserting only the bag produces the same mirror values the
+ *     dual-write produced.
+ *   - An INSERT that names either mirror column errors (the reason every
+ *     writer was stripped in this PR).
+ *   - The retag RPC (redefined here to SET only the bag) still updates a
+ *     posted line under its carve-out, and the mirrors recompute.
+ */
+
+async function seedTenant() {
+  const userId = await insertAuthUser()
+  const companyId = await insertCompany({ createdBy: userId })
+  await insertCompanyMember({ companyId, userId, role: 'owner' })
+  const fiscalPeriodId = await insertFiscalPeriod({
+    userId,
+    companyId,
+    periodStart: '2026-01-01',
+    periodEnd: '2026-12-31',
+  })
+  return { userId, companyId, fiscalPeriodId }
+}
+
+describe('journal_entry_lines generated mirrors (PR9 cutover)', () => {
+  it('derives cost_center/project from the bag on insert; empty bag yields NULLs', async () => {
+    const { userId, companyId, fiscalPeriodId } = await seedTenant()
+    const entryId = await insertDraftJournalEntry({ userId, companyId, fiscalPeriodId })
+
+    const { rows } = await getPool().query<{
+      dimensions: Record<string, string>
+      cost_center: string | null
+      project: string | null
+    }>(
+      `INSERT INTO public.journal_entry_lines
+         (journal_entry_id, account_number, debit_amount, credit_amount, dimensions)
+       VALUES ($1, '4010', 1000, 0, '{"1":"KS01","6":"P001"}'::jsonb),
+              ($1, '1930', 0, 1000, '{}'::jsonb)
+       RETURNING dimensions, cost_center, project`,
+      [entryId],
+    )
+
+    const tagged = rows.find((r) => r.dimensions['1'])!
+    expect(tagged.cost_center).toBe('KS01')
+    expect(tagged.project).toBe('P001')
+
+    const untagged = rows.find((r) => !r.dimensions['1'])!
+    expect(untagged.cost_center).toBeNull()
+    expect(untagged.project).toBeNull()
+  })
+
+  it('rejects an INSERT that names a mirror column explicitly', async () => {
+    const { userId, companyId, fiscalPeriodId } = await seedTenant()
+    const entryId = await insertDraftJournalEntry({ userId, companyId, fiscalPeriodId })
+
+    await expect(
+      getPool().query(
+        `INSERT INTO public.journal_entry_lines
+           (journal_entry_id, account_number, debit_amount, credit_amount, dimensions, cost_center)
+         VALUES ($1, '4010', 1000, 0, '{"1":"KS01"}'::jsonb, 'KS01')`,
+        [entryId],
+      ),
+    ).rejects.toThrow(/non-DEFAULT value into column/i)
+  })
+
+  it('mirrors recompute when a draft bag is updated (bag-only write)', async () => {
+    const { userId, companyId, fiscalPeriodId } = await seedTenant()
+    const entryId = await insertDraftJournalEntry({ userId, companyId, fiscalPeriodId })
+    const { rows } = await getPool().query<{ id: string }>(
+      `INSERT INTO public.journal_entry_lines
+         (journal_entry_id, account_number, debit_amount, credit_amount, dimensions)
+       VALUES ($1, '4010', 500, 0, '{"6":"P001"}'::jsonb)
+       RETURNING id`,
+      [entryId],
+    )
+
+    await getPool().query(
+      `UPDATE public.journal_entry_lines SET dimensions = '{"1":"KS02"}'::jsonb WHERE id = $1`,
+      [rows[0].id],
+    )
+    const after = await getPool().query<{ cost_center: string | null; project: string | null }>(
+      `SELECT cost_center, project FROM public.journal_entry_lines WHERE id = $1`,
+      [rows[0].id],
+    )
+    expect(after.rows[0].cost_center).toBe('KS02')
+    expect(after.rows[0].project).toBeNull()
+  })
+})

tests/pg/dimensions-substrate.pg.test.ts

@@ -47,16 +47,14 @@ async function insertDimensionedLines(
   const lineId = randomUUID()
   await getPool().query(
     `INSERT INTO public.journal_entry_lines
-       (id, journal_entry_id, account_number, debit_amount, credit_amount, dimensions, cost_center, project)
-     VALUES ($1, $2, '4010', $3, 0, $4, $5, $6),
-            (gen_random_uuid(), $2, '1930', 0, $3, '{}', NULL, NULL)`,
+       (id, journal_entry_id, account_number, debit_amount, credit_amount, dimensions)
+     VALUES ($1, $2, '4010', $3, 0, $4),
+            (gen_random_uuid(), $2, '1930', 0, $3, '{}')`,
     [
       lineId,
       journalEntryId,
       amount,
       JSON.stringify(dimensions),
-      dimensions['1'] ?? null,
-      dimensions['6'] ?? null,
     ],
   )
   return lineId
@@ -267,9 +265,9 @@ describe('journal_entry_lines.dimensions', () => {
     const entryId = await insertDraftJournalEntry({ userId, companyId, fiscalPeriodId })
     const lineId = await insertDimensionedLines(entryId, { '6': 'P001' })
 
-    // Draft: retagging is allowed
+    // Draft: retagging is allowed (PR9: the bag alone — mirrors generate)
     await getPool().query(
-      `UPDATE public.journal_entry_lines SET dimensions = '{"6":"P002"}', project = 'P002' WHERE id = $1`,
+      `UPDATE public.journal_entry_lines SET dimensions = '{"6":"P002"}' WHERE id = $1`,
       [lineId],
     )