feat(services): Slice B.2 dual-write — RuleEditorService writes deadline_rules AND procedural_events / sequencing_rules / legal_sources (t-paliad-305 / m/paliad#93)

Keeps the parallel new tables (mig 136, Slice B.1) in lock-step with
the legacy paliad.deadline_rules table through every write path on
RuleEditorService. Read paths stay on deadline_rules in B.2 — B.3
flips them and stops legacy writes.

* internal/services/dual_write.go (new) —
  - syncDualWriteFromDeadlineRule(ctx, tx, id): idempotent UPSERT of
    legal_sources + procedural_events + sequencing_rules from the
    just-written deadline_rules row. Pure SQL projection, no Go-side
    struct mapping. Synthetic-code mint expression is byte-identical
    to mig 136 ('null.' || first 8 hex of stripped uuid).
  - syncDeadlineDualLinks(ctx, tx, deadlineID): mirrors a deadline's
    legacy rule_id back-link onto deadlines.procedural_event_id +
    sequencing_rule_id. Handles NULL rule_id naturally (collapses both
    new columns to NULL).
  - CheckDualWriteDrift(ctx, conn): nine read-only count queries +
    integrity joins. Returns DualWriteDriftReport. HasDrift() bool for
    log routing.
  - StartDualWriteDriftCheckLoop(ctx, conn, interval): goroutine ticker
    that runs CheckDualWriteDrift every `interval` (default 6h) for
    the lifetime of ctx. Clean run logs at INFO; drift at WARN with
    full report.

* internal/services/rule_editor_service.go —
  - Create / UpdateDraft / CloneAsDraft / Publish / flipLifecycle
    each call syncDualWriteFromDeadlineRule(ctx, tx, id) after the
    deadline_rules mutation, before tx.Commit. Publish syncs BOTH the
    published draft AND the cloned-from peer it just archived as a
    cascade. The audit_reason already set via setAuditReasonTx
    propagates to the new-table writes (same TX, same session).

* internal/services/rule_editor_orphans.go —
  - ResolveOrphan calls syncDeadlineDualLinks after UPDATE
    paliad.deadlines SET rule_id = $1, so the parallel new columns
    follow the legacy back-link.

* internal/services/deadline_service.go —
  - DeadlineService.Update calls syncDeadlineDualLinks when
    input.RuleSet is true (auto/custom rule swap from t-paliad-258).

* cmd/server/main.go —
  - Spawns StartDualWriteDriftCheckLoop alongside CalDAV sync and
    reminder scanner. Inherits bgCtx so the goroutine stops on
    SIGTERM. Interval 6h.

* internal/services/dual_write_test.go (new) —
  - TestDualWrite_RuleEditorLifecycle: Create → UpdateDraft → Publish
    → Archive, asserts the new tables mirror at each step. Final
    CheckDualWriteDrift returns zero drift.
  - TestDualWrite_SyntheticCodeForNullSubmission: rule created with
    submission_code=NULL gets a 'null.<8hex>' procedural_events row
    matching mig 136's mint expression byte-for-byte.

Scope decisions documented in the commit:

- B.2 keeps read paths on deadline_rules. paliadin's "Read paths fall
  back to legacy" reads as "reads stay on legacy as the safety net
  while drift-check validates the new tables". B.3 swaps reads to
  new tables only AND stops writing to deadline_rules — that's a
  separate slice per the design's §5.2/§5.3 split.

- B.2 does NOT modify submission_drafts, projection_service, the
  Fristenrechner calculator, the SubmissionVarsService, the
  Schriftsätze list query, or any other reader. They keep reading
  deadline_rules unchanged. The new tables are populated in parallel
  for B.3's cutover.

- Audit triggers on deadline_rules continue to fire as before. The
  new tables have no audit triggers yet (a later slice can add
  parallel audit rows once the new tables are authoritative).

- Drift-check uses default 6h interval — short enough that a broken
  dual-write surfaces within the same business day, long enough that
  the count-COUNTs don't churn the pool. Override via the caller in
  cmd/server.

Hard rules followed:
- audit_reason set on every TX before any deadline_rules mutation
  (existing pattern; new-table writes share the same reason).
- No destructive op (B.2 is strictly additive in behaviour).
- New helpers idempotent (UPSERT ON CONFLICT DO UPDATE) — safe to
  call twice, safe to re-run after a partial failure.

Build + vet clean. TestMigrations_NoDuplicateSlot passes.

cmd/server/main.go

@@ -12,6 +12,7 @@ import (
 	"strconv"
 	"strings"
 	"syscall"
+	"time"
 
 	// Embed Go's IANA tz database into the binary so time.LoadLocation works
 	// without OS tzdata. The runtime image (alpine) doesn't ship /usr/share/
@@ -337,6 +338,13 @@ func main() {
 			log.Printf("CalDAV start: %v", err)
 		}
 		reminderSvc.Start(bgCtx)
+		// Slice B.2 dual-write drift check (t-paliad-305 / m/paliad#93).
+		// Runs every 6 h while the new procedural_events / sequencing_rules /
+		// legal_sources tables shadow the legacy paliad.deadline_rules
+		// table. A clean run logs at INFO; drift logs at WARN with the
+		// full report so a broken dual-write surfaces before the next
+		// deploy.
+		services.StartDualWriteDriftCheckLoop(bgCtx, pool, 6*time.Hour)
 		go func() {
 			<-bgCtx.Done()
 			log.Println("background services: shutdown signal received")

internal/services/deadline_service.go

@@ -585,6 +585,16 @@ func (s *DeadlineService) Update(ctx context.Context, userID, deadlineID uuid.UU
 		if _, err := tx.ExecContext(ctx, query, args...); err != nil {
 			return nil, fmt.Errorf("update deadline: %w", err)
 		}
+		// Slice B.2 dual-write (t-paliad-305): if rule_id was in the
+		// patch (auto/custom swap from t-paliad-258), the parallel
+		// procedural_event_id + sequencing_rule_id columns must follow.
+		// Call unconditionally — it's a single UPDATE keyed on
+		// deadlineID and a no-op when rule_id is unchanged.
+		if input.RuleSet {
+			if err := syncDeadlineDualLinks(ctx, tx, deadlineID); err != nil {
+				return nil, err
+			}
+		}
 	}
 
 	if input.EventTypeIDs != nil && s.eventTypes != nil {

internal/services/dual_write.go

@@ -0,0 +1,392 @@
+// Slice B.2 dual-write (t-paliad-305 / m/paliad#93) — keep paliad's
+// new tables (procedural_events / sequencing_rules / legal_sources) in
+// lock-step with the legacy paliad.deadline_rules table during the
+// dual-write window. Mig 136 (Slice B.1) created the new tables and
+// backfilled them once. This file keeps them in sync going forward.
+//
+// Contract:
+//
+//   - Every RuleEditorService method that mutates paliad.deadline_rules
+//     calls syncDualWriteFromDeadlineRule(ctx, tx, id) inside the same
+//     transaction, AFTER the deadline_rules write, BEFORE tx.Commit.
+//   - The sync is idempotent (INSERT … ON CONFLICT … DO UPDATE) so the
+//     same call works for Create (new row), UpdateDraft (existing row),
+//     CloneAsDraft (new row referencing an old row), Publish (lifecycle
+//     flip), Archive/Restore (lifecycle flip), and the published-peer
+//     archive that Publish performs as a cascade.
+//   - The sync re-derives the new-table state from paliad.deadline_rules
+//     in pure SQL — no struct mapping in Go. The legacy table stays the
+//     source of truth during B.2 (B.3 flips reads, B.4 drops it).
+//   - Read paths still read deadline_rules in B.2. The new tables are a
+//     parallel projection kept consistent for B.3's read cutover; they
+//     are not yet authoritative.
+//
+// Why a per-row sync instead of a global trigger:
+//
+//   - The deadline_rules audit trigger (mig 079) reads paliad.audit_reason
+//     to record the rationale on every change. Putting the new-table
+//     write in the same TX preserves that auditability — set_config is
+//     transactional and the new writes share the same reason.
+//   - A Postgres-side AFTER UPDATE trigger on deadline_rules would also
+//     work but it's harder to test in isolation and harder to revert
+//     when B.4 drops the source table. A Go-side sync is reversible
+//     with a code revert; an SQL trigger needs a follow-up migration.
+//
+// The drift-check job (CheckDualWriteDrift below) runs daily and
+// alerts on mismatches. If the sync ever silently misses a row, the
+// drift check surfaces it inside one day.
+//
+// See docs/design-procedural-events-model-2026-05-25.md §5.2 (dual-write
+// phase) and docs/design-procedural-events-b0-findings-2026-05-26.md §7.
+package services
+
+import (
+	"context"
+	"fmt"
+	"log"
+	"time"
+
+	"github.com/google/uuid"
+	"github.com/jmoiron/sqlx"
+)
+
+// syncDualWriteFromDeadlineRule re-projects the deadline_rules row with
+// the given id into legal_sources + procedural_events + sequencing_rules.
+// Runs three UPSERT statements in the open transaction.
+//
+// Synthetic-code rule (for rows where deadline_rules.submission_code is
+// NULL) mirrors mig 136's backfill: 'null.' || first 8 hex chars of the
+// uuid (dashes stripped). This must stay byte-identical to the mig 136
+// expression or the lookup join inside the sequencing_rules UPSERT
+// misses.
+func syncDualWriteFromDeadlineRule(ctx context.Context, tx *sqlx.Tx, id uuid.UUID) error {
+	// 1. legal_sources — UPSERT the citation (no-op if already present).
+	//    jurisdiction is parsed from the first dot-separated segment;
+	//    'other' on empty (paranoid fallback, no live rows hit it).
+	if _, err := tx.ExecContext(ctx, `
+		INSERT INTO paliad.legal_sources (citation, jurisdiction)
+		SELECT dr.legal_source,
+		       COALESCE(NULLIF(split_part(dr.legal_source, '.', 1), ''), 'other')
+		  FROM paliad.deadline_rules dr
+		 WHERE dr.id = $1 AND dr.legal_source IS NOT NULL
+		ON CONFLICT (citation) DO NOTHING`, id); err != nil {
+		return fmt.Errorf("dual-write legal_sources for rule %s: %w", id, err)
+	}
+
+	// 2. procedural_events — UPSERT keyed by code. The code is the
+	//    submission_code if present, else the synthetic 'null.<8hex>'
+	//    minted from the deadline_rules row's id (matches mig 136).
+	//    legal_source_id is resolved by JOIN on legal_sources.citation
+	//    (NULL when the rule has no legal_source).
+	if _, err := tx.ExecContext(ctx, `
+		INSERT INTO paliad.procedural_events
+		    (code, name, name_en, description, event_kind,
+		     primary_party_default, legal_source_id, concept_id,
+		     lifecycle_state, published_at, is_active)
+		SELECT
+		    COALESCE(dr.submission_code,
+		             'null.' || substring(replace(dr.id::text, '-', ''), 1, 8)),
+		    dr.name, dr.name_en, dr.description, dr.event_type,
+		    dr.primary_party, ls.id, dr.concept_id,
+		    dr.lifecycle_state, dr.published_at, dr.is_active
+		  FROM paliad.deadline_rules dr
+		  LEFT JOIN paliad.legal_sources ls ON ls.citation = dr.legal_source
+		 WHERE dr.id = $1
+		ON CONFLICT (code) DO UPDATE SET
+		    name                  = EXCLUDED.name,
+		    name_en               = EXCLUDED.name_en,
+		    description           = EXCLUDED.description,
+		    event_kind            = EXCLUDED.event_kind,
+		    primary_party_default = EXCLUDED.primary_party_default,
+		    legal_source_id       = EXCLUDED.legal_source_id,
+		    concept_id            = EXCLUDED.concept_id,
+		    lifecycle_state       = EXCLUDED.lifecycle_state,
+		    published_at          = EXCLUDED.published_at,
+		    is_active             = EXCLUDED.is_active,
+		    updated_at            = now()`, id); err != nil {
+		return fmt.Errorf("dual-write procedural_events for rule %s: %w", id, err)
+	}
+
+	// 3. sequencing_rules — UPSERT keyed by id (1:1 inheritance from
+	//    deadline_rules.id). procedural_event_id resolved by JOIN on
+	//    the (real or synthetic) code. All hat-3 mechanics columns copy
+	//    1:1 from the deadline_rules row's post-write state.
+	if _, err := tx.ExecContext(ctx, `
+		INSERT INTO paliad.sequencing_rules
+		    (id, procedural_event_id, proceeding_type_id, parent_id, trigger_event_id,
+		     duration_value, duration_unit, timing,
+		     alt_duration_value, alt_duration_unit, alt_rule_code, anchor_alt,
+		     combine_op, condition_expr, primary_party, sequence_order,
+		     is_spawn, spawn_label, spawn_proceeding_type_id,
+		     is_bilateral, is_court_set, priority,
+		     rule_code, rule_codes, deadline_notes, deadline_notes_en,
+		     choices_offered, applies_to_target,
+		     lifecycle_state, draft_of, published_at, is_active,
+		     created_at, updated_at)
+		SELECT
+		    dr.id, pe.id,
+		    dr.proceeding_type_id, dr.parent_id, dr.trigger_event_id,
+		    dr.duration_value, dr.duration_unit, dr.timing,
+		    dr.alt_duration_value, dr.alt_duration_unit, dr.alt_rule_code, dr.anchor_alt,
+		    dr.combine_op, dr.condition_expr, dr.primary_party, dr.sequence_order,
+		    dr.is_spawn, dr.spawn_label, dr.spawn_proceeding_type_id,
+		    dr.is_bilateral, dr.is_court_set, dr.priority,
+		    dr.rule_code, dr.rule_codes, dr.deadline_notes, dr.deadline_notes_en,
+		    dr.choices_offered, dr.applies_to_target,
+		    dr.lifecycle_state, dr.draft_of, dr.published_at, dr.is_active,
+		    dr.created_at, dr.updated_at
+		  FROM paliad.deadline_rules dr
+		  JOIN paliad.procedural_events pe
+		    ON pe.code = COALESCE(dr.submission_code,
+		                          'null.' || substring(replace(dr.id::text, '-', ''), 1, 8))
+		 WHERE dr.id = $1
+		ON CONFLICT (id) DO UPDATE SET
+		    procedural_event_id      = EXCLUDED.procedural_event_id,
+		    proceeding_type_id       = EXCLUDED.proceeding_type_id,
+		    parent_id                = EXCLUDED.parent_id,
+		    trigger_event_id         = EXCLUDED.trigger_event_id,
+		    duration_value           = EXCLUDED.duration_value,
+		    duration_unit            = EXCLUDED.duration_unit,
+		    timing                   = EXCLUDED.timing,
+		    alt_duration_value       = EXCLUDED.alt_duration_value,
+		    alt_duration_unit        = EXCLUDED.alt_duration_unit,
+		    alt_rule_code            = EXCLUDED.alt_rule_code,
+		    anchor_alt               = EXCLUDED.anchor_alt,
+		    combine_op               = EXCLUDED.combine_op,
+		    condition_expr           = EXCLUDED.condition_expr,
+		    primary_party            = EXCLUDED.primary_party,
+		    sequence_order           = EXCLUDED.sequence_order,
+		    is_spawn                 = EXCLUDED.is_spawn,
+		    spawn_label              = EXCLUDED.spawn_label,
+		    spawn_proceeding_type_id = EXCLUDED.spawn_proceeding_type_id,
+		    is_bilateral             = EXCLUDED.is_bilateral,
+		    is_court_set             = EXCLUDED.is_court_set,
+		    priority                 = EXCLUDED.priority,
+		    rule_code                = EXCLUDED.rule_code,
+		    rule_codes               = EXCLUDED.rule_codes,
+		    deadline_notes           = EXCLUDED.deadline_notes,
+		    deadline_notes_en        = EXCLUDED.deadline_notes_en,
+		    choices_offered          = EXCLUDED.choices_offered,
+		    applies_to_target        = EXCLUDED.applies_to_target,
+		    lifecycle_state          = EXCLUDED.lifecycle_state,
+		    draft_of                 = EXCLUDED.draft_of,
+		    published_at             = EXCLUDED.published_at,
+		    is_active                = EXCLUDED.is_active,
+		    updated_at               = now()`, id); err != nil {
+		return fmt.Errorf("dual-write sequencing_rules for rule %s: %w", id, err)
+	}
+
+	return nil
+}
+
+// syncDeadlineDualLinks mirrors a deadline's legacy rule_id back-link
+// onto the new procedural_event_id + sequencing_rule_id columns added
+// by mig 136. Call this within an open transaction AFTER any UPDATE
+// that mutates paliad.deadlines.rule_id (mig 122 introduced rule_id
+// as the deadline→rule FK; today's writers are DeadlineService.Update
+// and RuleEditorService.ResolveOrphan).
+//
+// Idempotent: NULL rule_id collapses both new columns to NULL by virtue
+// of the subquery returning NULL. Slice B.2 (t-paliad-305).
+func syncDeadlineDualLinks(ctx context.Context, tx *sqlx.Tx, deadlineID uuid.UUID) error {
+	if _, err := tx.ExecContext(ctx, `
+		UPDATE paliad.deadlines d
+		   SET sequencing_rule_id  = d.rule_id,
+		       procedural_event_id = (
+		           SELECT sr.procedural_event_id
+		             FROM paliad.sequencing_rules sr
+		            WHERE sr.id = d.rule_id
+		       )
+		 WHERE d.id = $1`, deadlineID); err != nil {
+		return fmt.Errorf("sync deadline dual-links for %s: %w", deadlineID, err)
+	}
+	return nil
+}
+
+// DualWriteDriftReport summarises the comparison between the legacy
+// paliad.deadline_rules table and the new procedural_events /
+// sequencing_rules tables that B.2's dual-write is meant to keep in
+// sync. A zero-drift report (every count delta zero, every join clean)
+// is the steady state during the dual-write window; any non-zero field
+// is the signal that a write path either bypassed
+// syncDualWriteFromDeadlineRule or that an out-of-band mutation
+// happened (e.g. raw SQL run by an operator).
+type DualWriteDriftReport struct {
+	// Counts on the legacy and the projected side.
+	DeadlineRules    int `json:"deadline_rules"`
+	SequencingRules  int `json:"sequencing_rules"`
+	ProceduralEvents int `json:"procedural_events"`
+	LegalSources     int `json:"legal_sources"`
+
+	// Expected (from the legacy side) vs observed (on the new side).
+	ExpectedPE           int `json:"expected_procedural_events"`
+	ExpectedLegalSources int `json:"expected_legal_sources"`
+
+	// MissingSR — deadline_rules rows with no sequencing_rules row by id.
+	// OrphanedSR — sequencing_rules rows whose id doesn't exist in
+	// deadline_rules anymore (would only happen with a deletion path
+	// that bypasses dual-write).
+	MissingSR  int `json:"missing_sequencing_rules"`
+	OrphanedSR int `json:"orphaned_sequencing_rules"`
+
+	// MismatchedLifecycle — rows where deadline_rules.lifecycle_state
+	// disagrees with sequencing_rules.lifecycle_state. Should always be
+	// zero during dual-write.
+	MismatchedLifecycle int `json:"mismatched_lifecycle"`
+
+	// MismatchedActive — same shape, for is_active.
+	MismatchedActive int `json:"mismatched_active"`
+}
+
+// HasDrift returns true if any field signals divergence between the
+// legacy and projected sides. Used by the drift-check ticker to decide
+// whether to log at WARN (drift) or INFO (clean).
+func (r DualWriteDriftReport) HasDrift() bool {
+	if r.SequencingRules != r.DeadlineRules {
+		return true
+	}
+	if r.ProceduralEvents != r.ExpectedPE {
+		return true
+	}
+	if r.LegalSources != r.ExpectedLegalSources {
+		return true
+	}
+	if r.MissingSR != 0 || r.OrphanedSR != 0 {
+		return true
+	}
+	if r.MismatchedLifecycle != 0 || r.MismatchedActive != 0 {
+		return true
+	}
+	return false
+}
+
+// CheckDualWriteDrift compares the legacy paliad.deadline_rules table
+// against the parallel new tables maintained by Slice B.2's dual-write.
+// Returns a DualWriteDriftReport — caller decides what to do with
+// non-zero drift (log, page, fail healthcheck, etc.).
+//
+// Read-only. Safe to run against prod. Single query per metric so the
+// pool isn't held for a long time. No locks; tolerates concurrent
+// writes (counts may shift by one or two during the read, but a
+// persistent drift > 0 is the alarm signal).
+func CheckDualWriteDrift(ctx context.Context, conn *sqlx.DB) (*DualWriteDriftReport, error) {
+	var r DualWriteDriftReport
+
+	q := func(label, sql string, dst *int) error {
+		if err := conn.GetContext(ctx, dst, sql); err != nil {
+			return fmt.Errorf("drift-check %s: %w", label, err)
+		}
+		return nil
+	}
+
+	if err := q("dr_total", `SELECT COUNT(*) FROM paliad.deadline_rules`, &r.DeadlineRules); err != nil {
+		return nil, err
+	}
+	if err := q("sr_total", `SELECT COUNT(*) FROM paliad.sequencing_rules`, &r.SequencingRules); err != nil {
+		return nil, err
+	}
+	if err := q("pe_total", `SELECT COUNT(*) FROM paliad.procedural_events`, &r.ProceduralEvents); err != nil {
+		return nil, err
+	}
+	if err := q("ls_total", `SELECT COUNT(*) FROM paliad.legal_sources`, &r.LegalSources); err != nil {
+		return nil, err
+	}
+
+	if err := q("expected_pe", `
+		SELECT
+		  (SELECT COUNT(DISTINCT submission_code) FROM paliad.deadline_rules WHERE submission_code IS NOT NULL)
+		  +
+		  (SELECT COUNT(*) FROM paliad.deadline_rules WHERE submission_code IS NULL)
+	`, &r.ExpectedPE); err != nil {
+		return nil, err
+	}
+	if err := q("expected_ls",
+		`SELECT COUNT(DISTINCT legal_source) FROM paliad.deadline_rules WHERE legal_source IS NOT NULL`,
+		&r.ExpectedLegalSources); err != nil {
+		return nil, err
+	}
+
+	if err := q("missing_sr", `
+		SELECT COUNT(*) FROM paliad.deadline_rules dr
+		  LEFT JOIN paliad.sequencing_rules sr ON sr.id = dr.id
+		 WHERE sr.id IS NULL`, &r.MissingSR); err != nil {
+		return nil, err
+	}
+	if err := q("orphaned_sr", `
+		SELECT COUNT(*) FROM paliad.sequencing_rules sr
+		  LEFT JOIN paliad.deadline_rules dr ON dr.id = sr.id
+		 WHERE dr.id IS NULL`, &r.OrphanedSR); err != nil {
+		return nil, err
+	}
+
+	if err := q("mismatched_lifecycle", `
+		SELECT COUNT(*) FROM paliad.deadline_rules dr
+		  JOIN paliad.sequencing_rules sr ON sr.id = dr.id
+		 WHERE dr.lifecycle_state <> sr.lifecycle_state`, &r.MismatchedLifecycle); err != nil {
+		return nil, err
+	}
+	if err := q("mismatched_active", `
+		SELECT COUNT(*) FROM paliad.deadline_rules dr
+		  JOIN paliad.sequencing_rules sr ON sr.id = dr.id
+		 WHERE dr.is_active <> sr.is_active`, &r.MismatchedActive); err != nil {
+		return nil, err
+	}
+
+	return &r, nil
+}
+
+// StartDualWriteDriftCheckLoop runs CheckDualWriteDrift on a fixed
+// interval for the lifetime of ctx. A clean run logs at INFO level;
+// drift logs at WARN level with the full report payload. The first
+// check fires after `interval`, not immediately on Start — by the time
+// the ticker first fires the process has finished booting and the
+// initial backfill + dual-write writes have settled.
+//
+// Slice B.2 (t-paliad-305). interval should be short enough to surface
+// drift before the next deploy (so a broken dual-write doesn't sit
+// silent for a week) and long enough to avoid noise (the check holds
+// no locks but it does run nine SELECT COUNTs).
+//
+// Recommended interval: 6h. Override via the caller (cmd/server picks
+// the runtime value).
+func StartDualWriteDriftCheckLoop(ctx context.Context, conn *sqlx.DB, interval time.Duration) {
+	if interval <= 0 {
+		interval = 6 * time.Hour
+	}
+	go func() {
+		t := time.NewTicker(interval)
+		defer t.Stop()
+		for {
+			select {
+			case <-ctx.Done():
+				return
+			case <-t.C:
+				report, err := CheckDualWriteDrift(ctx, conn)
+				if err != nil {
+					log.Printf("dual-write drift-check: error: %v", err)
+					continue
+				}
+				if report.HasDrift() {
+					log.Printf("dual-write drift-check: DRIFT DETECTED — "+
+						"deadline_rules=%d sequencing_rules=%d "+
+						"procedural_events=%d (expected %d) "+
+						"legal_sources=%d (expected %d) "+
+						"missing_sr=%d orphaned_sr=%d "+
+						"mismatched_lifecycle=%d mismatched_active=%d",
+						report.DeadlineRules, report.SequencingRules,
+						report.ProceduralEvents, report.ExpectedPE,
+						report.LegalSources, report.ExpectedLegalSources,
+						report.MissingSR, report.OrphanedSR,
+						report.MismatchedLifecycle, report.MismatchedActive)
+				} else {
+					log.Printf("dual-write drift-check: OK — "+
+						"deadline_rules=%d sequencing_rules=%d "+
+						"procedural_events=%d legal_sources=%d",
+						report.DeadlineRules, report.SequencingRules,
+						report.ProceduralEvents, report.LegalSources)
+				}
+			}
+		}
+	}()
+}
+

internal/services/dual_write_test.go

@@ -0,0 +1,300 @@
+// Slice B.2 dual-write tests (t-paliad-305 / m/paliad#93).
+//
+// Asserts the parallel projection — paliad.procedural_events +
+// paliad.sequencing_rules + paliad.legal_sources — stays in lock-step
+// with paliad.deadline_rules through the full RuleEditorService
+// lifecycle. Skipped when TEST_DATABASE_URL is unset.
+
+package services
+
+import (
+	"context"
+	"os"
+	"testing"
+
+	"github.com/jmoiron/sqlx"
+	_ "github.com/lib/pq"
+
+	"mgit.msbls.de/m/paliad/internal/db"
+)
+
+// TestDualWrite_RuleEditorLifecycle walks Create → UpdateDraft →
+// CloneAsDraft → Publish → Archive → Restore on RuleEditorService and
+// after each operation asserts that paliad.sequencing_rules has the
+// 1:1 mirror, paliad.procedural_events carries the projected identity,
+// and paliad.legal_sources carries the citation.
+func TestDualWrite_RuleEditorLifecycle(t *testing.T) {
+	url := os.Getenv("TEST_DATABASE_URL")
+	if url == "" {
+		t.Skip("TEST_DATABASE_URL not set — skipping live DB test")
+	}
+	if err := db.ApplyMigrations(url); err != nil {
+		t.Fatalf("apply migrations: %v", err)
+	}
+	pool, err := sqlx.Connect("postgres", url)
+	if err != nil {
+		t.Fatalf("connect: %v", err)
+	}
+	defer pool.Close()
+
+	ctx := context.Background()
+	rules := NewDeadlineRuleService(pool)
+	svc := NewRuleEditorService(pool, rules)
+
+	cleanup := func() {
+		pool.ExecContext(ctx,
+			`SELECT set_config('paliad.audit_reason', 'slice b.2 test cleanup', true)`)
+		// Order matters: sequencing_rules → procedural_events → legal_sources
+		// (FK direction). deadline_rules cleanup last because mig 079 audit
+		// trigger captures the DELETE.
+		pool.ExecContext(ctx, `DELETE FROM paliad.sequencing_rules WHERE id IN (
+			SELECT id FROM paliad.deadline_rules WHERE name LIKE 'SLICEB2_TEST_%'
+		)`)
+		pool.ExecContext(ctx, `DELETE FROM paliad.procedural_events
+			WHERE code LIKE 'sliceb2.%' OR code LIKE 'null.sliceb2%'`)
+		pool.ExecContext(ctx, `DELETE FROM paliad.legal_sources
+			WHERE citation LIKE 'SLICEB2.%'`)
+		pool.ExecContext(ctx,
+			`DELETE FROM paliad.deadline_rules WHERE name LIKE 'SLICEB2_TEST_%'`)
+		pool.ExecContext(ctx,
+			`DELETE FROM paliad.proceeding_types WHERE code = 'SLICEB2_TEST_PT'`)
+	}
+	cleanup()
+	defer cleanup()
+
+	var ptID int
+	if err := pool.GetContext(ctx, &ptID, `
+		INSERT INTO paliad.proceeding_types (code, name, name_en, category, jurisdiction, is_active)
+		VALUES ('SLICEB2_TEST_PT', 'Slice B.2 Test PT', 'Slice B.2 Test PT', 'fristenrechner', 'UPC', true)
+		RETURNING id`); err != nil {
+		t.Fatalf("seed proceeding_type: %v", err)
+	}
+
+	subCode := "sliceb2.create"
+	legalSrc := "SLICEB2.PatG.1"
+
+	// 1. Create — assert the parallel rows land.
+	created, err := svc.Create(ctx, CreateRuleInput{
+		Name:             "SLICEB2_TEST_create",
+		NameEN:           "SLICEB2_TEST_create_EN",
+		ProceedingTypeID: &ptID,
+		SubmissionCode:   &subCode,
+		LegalSource:      &legalSrc,
+		DurationValue:    30,
+		DurationUnit:     "days",
+		Priority:         "mandatory",
+	}, "B.2 dual-write create test")
+	if err != nil {
+		t.Fatalf("Create: %v", err)
+	}
+
+	// legal_sources should now carry SLICEB2.PatG.1
+	var lsCount int
+	if err := pool.GetContext(ctx, &lsCount,
+		`SELECT COUNT(*) FROM paliad.legal_sources WHERE citation = $1`, legalSrc); err != nil {
+		t.Fatalf("query legal_sources: %v", err)
+	}
+	if lsCount != 1 {
+		t.Errorf("legal_sources after Create: got %d, want 1 for citation %q", lsCount, legalSrc)
+	}
+
+	// procedural_events should carry the submission_code
+	var peName, peLifecycle string
+	if err := pool.GetContext(ctx, &peName,
+		`SELECT name FROM paliad.procedural_events WHERE code = $1`, subCode); err != nil {
+		t.Fatalf("query procedural_events name: %v", err)
+	}
+	if peName != "SLICEB2_TEST_create" {
+		t.Errorf("procedural_events.name after Create: got %q, want %q", peName, "SLICEB2_TEST_create")
+	}
+	if err := pool.GetContext(ctx, &peLifecycle,
+		`SELECT lifecycle_state FROM paliad.procedural_events WHERE code = $1`, subCode); err != nil {
+		t.Fatalf("query procedural_events lifecycle: %v", err)
+	}
+	if peLifecycle != "draft" {
+		t.Errorf("procedural_events.lifecycle_state after Create: got %q, want %q", peLifecycle, "draft")
+	}
+
+	// sequencing_rules should have id = created.id and link to PE
+	var srCount, srMatchPE int
+	if err := pool.GetContext(ctx, &srCount,
+		`SELECT COUNT(*) FROM paliad.sequencing_rules WHERE id = $1`, created.ID); err != nil {
+		t.Fatalf("query sequencing_rules count: %v", err)
+	}
+	if srCount != 1 {
+		t.Errorf("sequencing_rules row after Create: got %d, want 1 for id %s", srCount, created.ID)
+	}
+	if err := pool.GetContext(ctx, &srMatchPE, `
+		SELECT COUNT(*) FROM paliad.sequencing_rules sr
+		  JOIN paliad.procedural_events pe ON pe.id = sr.procedural_event_id
+		 WHERE sr.id = $1 AND pe.code = $2`, created.ID, subCode); err != nil {
+		t.Fatalf("query sr→pe join: %v", err)
+	}
+	if srMatchPE != 1 {
+		t.Errorf("sequencing_rules.procedural_event_id after Create: got %d join hits, want 1", srMatchPE)
+	}
+
+	// 2. UpdateDraft — change name + legal_source. Assert propagation.
+	newName := "SLICEB2_TEST_updated"
+	newLegal := "SLICEB2.ZPO.2"
+	_, err = svc.UpdateDraft(ctx, created.ID, RulePatch{
+		Name:        &newName,
+		LegalSource: &newLegal,
+	}, "B.2 dual-write update test")
+	if err != nil {
+		t.Fatalf("UpdateDraft: %v", err)
+	}
+
+	var afterName string
+	if err := pool.GetContext(ctx, &afterName,
+		`SELECT name FROM paliad.procedural_events WHERE code = $1`, subCode); err != nil {
+		t.Fatalf("query pe.name post-update: %v", err)
+	}
+	if afterName != newName {
+		t.Errorf("procedural_events.name after UpdateDraft: got %q, want %q", afterName, newName)
+	}
+
+	// New citation must appear in legal_sources, and procedural_events.legal_source_id
+	// must point at it (idempotent UPSERT — the old SLICEB2.PatG.1 row stays).
+	var pePointsAtNewLegal int
+	if err := pool.GetContext(ctx, &pePointsAtNewLegal, `
+		SELECT COUNT(*) FROM paliad.procedural_events pe
+		  JOIN paliad.legal_sources ls ON ls.id = pe.legal_source_id
+		 WHERE pe.code = $1 AND ls.citation = $2`, subCode, newLegal); err != nil {
+		t.Fatalf("query pe→ls join: %v", err)
+	}
+	if pePointsAtNewLegal != 1 {
+		t.Errorf("procedural_events.legal_source_id after UpdateDraft: got %d hits, want 1", pePointsAtNewLegal)
+	}
+
+	// 3. Publish — flip to published. Assert lifecycle mirror.
+	_, err = svc.Publish(ctx, created.ID, "B.2 dual-write publish test")
+	if err != nil {
+		t.Fatalf("Publish: %v", err)
+	}
+	var srLifecycle, peLifecycleAfterPub string
+	if err := pool.GetContext(ctx, &srLifecycle,
+		`SELECT lifecycle_state FROM paliad.sequencing_rules WHERE id = $1`, created.ID); err != nil {
+		t.Fatalf("query sr.lifecycle: %v", err)
+	}
+	if srLifecycle != "published" {
+		t.Errorf("sequencing_rules.lifecycle_state after Publish: got %q, want %q", srLifecycle, "published")
+	}
+	if err := pool.GetContext(ctx, &peLifecycleAfterPub,
+		`SELECT lifecycle_state FROM paliad.procedural_events WHERE code = $1`, subCode); err != nil {
+		t.Fatalf("query pe.lifecycle post-publish: %v", err)
+	}
+	if peLifecycleAfterPub != "published" {
+		t.Errorf("procedural_events.lifecycle_state after Publish: got %q, want %q", peLifecycleAfterPub, "published")
+	}
+
+	// 4. Archive — flip to archived. Assert mirror.
+	_, err = svc.Archive(ctx, created.ID, "B.2 dual-write archive test")
+	if err != nil {
+		t.Fatalf("Archive: %v", err)
+	}
+	var srLifecycleArchived string
+	if err := pool.GetContext(ctx, &srLifecycleArchived,
+		`SELECT lifecycle_state FROM paliad.sequencing_rules WHERE id = $1`, created.ID); err != nil {
+		t.Fatalf("query sr.lifecycle post-archive: %v", err)
+	}
+	if srLifecycleArchived != "archived" {
+		t.Errorf("sequencing_rules.lifecycle_state after Archive: got %q, want %q", srLifecycleArchived, "archived")
+	}
+
+	// 5. Drift check should return zero drift right after the dance.
+	report, err := CheckDualWriteDrift(ctx, pool)
+	if err != nil {
+		t.Fatalf("CheckDualWriteDrift: %v", err)
+	}
+	if report.HasDrift() {
+		t.Errorf("CheckDualWriteDrift unexpectedly flagged drift: %+v", report)
+	}
+}
+
+// TestDualWrite_SyntheticCodeForNullSubmission asserts that a rule
+// created with submission_code=NULL gets a synthetic 'null.<8hex>'
+// procedural_events row matching mig 136's mint expression — so a new
+// draft without a code participates in the dual-write contract without
+// colliding with any code-bearing rule.
+func TestDualWrite_SyntheticCodeForNullSubmission(t *testing.T) {
+	url := os.Getenv("TEST_DATABASE_URL")
+	if url == "" {
+		t.Skip("TEST_DATABASE_URL not set — skipping live DB test")
+	}
+	if err := db.ApplyMigrations(url); err != nil {
+		t.Fatalf("apply migrations: %v", err)
+	}
+	pool, err := sqlx.Connect("postgres", url)
+	if err != nil {
+		t.Fatalf("connect: %v", err)
+	}
+	defer pool.Close()
+
+	ctx := context.Background()
+	rules := NewDeadlineRuleService(pool)
+	svc := NewRuleEditorService(pool, rules)
+
+	cleanup := func() {
+		pool.ExecContext(ctx, `SELECT set_config('paliad.audit_reason', 'slice b.2 null-code cleanup', true)`)
+		pool.ExecContext(ctx, `DELETE FROM paliad.sequencing_rules WHERE id IN (
+			SELECT id FROM paliad.deadline_rules WHERE name = 'SLICEB2_TEST_nullcode'
+		)`)
+		// Synthetic PE rows are keyed off the rule's uuid; delete by name reference.
+		pool.ExecContext(ctx, `DELETE FROM paliad.procedural_events
+			WHERE code IN (
+			  SELECT 'null.' || substring(replace(id::text, '-', ''), 1, 8)
+			    FROM paliad.deadline_rules WHERE name = 'SLICEB2_TEST_nullcode'
+			)`)
+		pool.ExecContext(ctx, `DELETE FROM paliad.deadline_rules WHERE name = 'SLICEB2_TEST_nullcode'`)
+		pool.ExecContext(ctx, `DELETE FROM paliad.proceeding_types WHERE code = 'SLICEB2_NC_PT'`)
+	}
+	cleanup()
+	defer cleanup()
+
+	var ptID int
+	if err := pool.GetContext(ctx, &ptID, `
+		INSERT INTO paliad.proceeding_types (code, name, name_en, category, jurisdiction, is_active)
+		VALUES ('SLICEB2_NC_PT', 'NC PT', 'NC PT', 'fristenrechner', 'UPC', true)
+		RETURNING id`); err != nil {
+		t.Fatalf("seed proceeding_type: %v", err)
+	}
+
+	created, err := svc.Create(ctx, CreateRuleInput{
+		Name:             "SLICEB2_TEST_nullcode",
+		NameEN:           "SLICEB2_TEST_nullcode_EN",
+		ProceedingTypeID: &ptID,
+		// SubmissionCode intentionally NIL → tests the synthetic-code branch.
+		DurationValue: 5,
+		DurationUnit:  "days",
+		Priority:      "mandatory",
+	}, "B.2 dual-write null-code test")
+	if err != nil {
+		t.Fatalf("Create: %v", err)
+	}
+
+	// Compute the expected synthetic code in the same way mig 136 / the
+	// dual-write helper do — keep the expression in lock-step with the
+	// SQL via this Go-side mirror.
+	var expectedCode string
+	if err := pool.GetContext(ctx, &expectedCode,
+		`SELECT 'null.' || substring(replace(id::text, '-', ''), 1, 8)
+		   FROM paliad.deadline_rules WHERE id = $1`, created.ID); err != nil {
+		t.Fatalf("compute expected synthetic code: %v", err)
+	}
+
+	var actualCode string
+	if err := pool.GetContext(ctx, &actualCode, `
+		SELECT pe.code
+		  FROM paliad.procedural_events pe
+		  JOIN paliad.sequencing_rules sr ON sr.procedural_event_id = pe.id
+		 WHERE sr.id = $1`, created.ID); err != nil {
+		t.Fatalf("query procedural_events via sequencing_rules: %v", err)
+	}
+	if actualCode != expectedCode {
+		t.Errorf("synthetic code mismatch: got %q, want %q", actualCode, expectedCode)
+	}
+	if len(actualCode) != len("null.")+8 {
+		t.Errorf("synthetic code length: got %d, want 13 (null.+8hex)", len(actualCode))
+	}
+}

internal/services/rule_editor_orphans.go

@@ -221,6 +221,12 @@ func (s *RuleEditorService) ResolveOrphan(ctx context.Context, orphanID uuid.UUI
 	); err != nil {
 		return fmt.Errorf("set deadline rule_id: %w", err)
 	}
+	// Slice B.2 dual-write (t-paliad-305): mirror the new linkage onto
+	// the parallel deadlines.procedural_event_id + sequencing_rule_id
+	// columns so they don't drift from rule_id.
+	if err := syncDeadlineDualLinks(ctx, tx, oc.DeadlineID); err != nil {
+		return err
+	}
 	if _, err := tx.ExecContext(ctx,
 		`UPDATE paliad.deadline_rule_backfill_orphans
 		    SET resolved_at      = $1,

internal/services/rule_editor_service.go

@@ -209,6 +209,14 @@ func (s *RuleEditorService) Create(ctx context.Context, input CreateRuleInput, r
 		return nil, fmt.Errorf("insert rule: %w", err)
 	}
 
+	// Slice B.2 dual-write (t-paliad-305): project the new row into
+	// legal_sources / procedural_events / sequencing_rules in the same
+	// transaction so the parallel tables stay in lock-step with
+	// deadline_rules through the B.3 read-cutover window.
+	if err := syncDualWriteFromDeadlineRule(ctx, tx, id); err != nil {
+		return nil, err
+	}
+
 	if err := tx.Commit(); err != nil {
 		return nil, fmt.Errorf("commit create: %w", err)
 	}
@@ -276,6 +284,10 @@ func (s *RuleEditorService) UpdateDraft(ctx context.Context, id uuid.UUID, patch
 	if _, err := tx.ExecContext(ctx, q, args...); err != nil {
 		return nil, fmt.Errorf("update rule draft: %w", err)
 	}
+	// Slice B.2 dual-write (t-paliad-305).
+	if err := syncDualWriteFromDeadlineRule(ctx, tx, id); err != nil {
+		return nil, err
+	}
 	if err := tx.Commit(); err != nil {
 		return nil, fmt.Errorf("commit update: %w", err)
 	}
@@ -336,6 +348,14 @@ func (s *RuleEditorService) CloneAsDraft(ctx context.Context, id uuid.UUID, reas
 	); err != nil {
 		return nil, fmt.Errorf("clone rule as draft: %w", err)
 	}
+	// Slice B.2 dual-write (t-paliad-305): new draft gets its own
+	// procedural_events + sequencing_rules row. The synthetic-code
+	// branch fires here when the source rule had NULL submission_code
+	// (the clone inherits the NULL and mints a fresh 'null.<8hex>'
+	// derived from newID).
+	if err := syncDualWriteFromDeadlineRule(ctx, tx, newID); err != nil {
+		return nil, err
+	}
 	if err := tx.Commit(); err != nil {
 		return nil, fmt.Errorf("commit clone: %w", err)
 	}
@@ -392,6 +412,18 @@ func (s *RuleEditorService) Publish(ctx context.Context, id uuid.UUID, reason st
 		}
 	}
 
+	// Slice B.2 dual-write (t-paliad-305): sync both sides — the newly
+	// published draft AND the cloned-from peer that just flipped to
+	// archived (if any).
+	if err := syncDualWriteFromDeadlineRule(ctx, tx, id); err != nil {
+		return nil, err
+	}
+	if current.DraftOf != nil {
+		if err := syncDualWriteFromDeadlineRule(ctx, tx, *current.DraftOf); err != nil {
+			return nil, err
+		}
+	}
+
 	if err := tx.Commit(); err != nil {
 		return nil, fmt.Errorf("commit publish: %w", err)
 	}
@@ -459,6 +491,12 @@ func (s *RuleEditorService) flipLifecycle(ctx context.Context, id uuid.UUID, tar
 		}
 	}
 
+	// Slice B.2 dual-write (t-paliad-305): mirror the lifecycle flip
+	// onto sequencing_rules + procedural_events.
+	if err := syncDualWriteFromDeadlineRule(ctx, tx, id); err != nil {
+		return nil, err
+	}
+
 	if err := tx.Commit(); err != nil {
 		return nil, fmt.Errorf("commit flip: %w", err)
 	}