feat(fristenrechner): sort post-trigger events by duration ASC within parent group (t-paliad-296)

Optional events anchored on the same trigger (e.g. the four
post-Entscheidung rules in upc.inf.cfi) used to render in catalog
sequence_order, so a 2-month rule (R.118.4 Folgeentscheidungen)
would precede a 1-month rule (R.151 Kostenentscheidung) chained
off the same decision. Now the calculator does a post-evaluation
permutation pass that sorts consecutive same-parent rows by
duration ascending — days < weeks < months < years, ties broken
by duration_value then submission_code.

Different trigger groups keep their proceeding-sequence position
— the walk only ever permutes rows that already share a parent.
Root rules (no parent) are never sorted against each other.
Court-set / conditional rows whose date isn't in the duration
ladder sort LAST within their group.

Verified order against m's report: R.151 cost_app + R.353
rectification (1-month tier) now render before R.220.1
appeal_spawn + R.118.4 cons_orders (2-month tier).

Issue: m/paliad#128

internal/services/fristenrechner.go

@@ -6,6 +6,7 @@ import (
 	"encoding/json"
 	"errors"
 	"fmt"
+	"sort"
 	"time"
 
 	"github.com/google/uuid"
@@ -867,6 +868,16 @@ func (s *FristenrechnerService) Calculate(ctx context.Context, proceedingCode, t
 		deadlines = append(deadlines, d)
 	}
 
+	// t-paliad-296: within consecutive runs of rules sharing the same
+	// trigger group (parent_id + trigger_event_id), reorder by duration
+	// ascending so optional events following the same anchor render in
+	// their likely-sequence order (a 1-month rule before a 2-month rule
+	// chained off the same decision). Different trigger groups keep
+	// their proceeding-sequence position — the chunk walk only sorts
+	// adjacent same-group rows. Court-set / conditional rows whose
+	// date isn't in the duration ladder sort LAST within their group.
+	sortDeadlinesByDurationWithinTriggerGroup(deadlines, ruleByID)
+
 	resp := &UIResponse{
 		ProceedingType:   pickedProceeding.Code,
 		ProceedingName:   pickedProceeding.Name,
@@ -893,6 +904,138 @@ func (s *FristenrechnerService) Calculate(ctx context.Context, proceedingCode, t
 	return resp, nil
 }
 
+// sortDeadlinesByDurationWithinTriggerGroup walks consecutive runs of
+// deadlines whose underlying rule shares the same trigger group
+// (parent_id + trigger_event_id) and reorders each run in place by
+// duration ascending. Different trigger groups keep their original
+// proceeding-sequence position — the walk only ever permutes adjacent
+// same-group rows.
+//
+// Sort key (within a run):
+//  1. Conditional / court-set rows (no concrete date in the duration
+//     ladder) sort LAST, tiebroken by submission_code.
+//  2. duration_unit weight ASC: days/working_days < weeks < months < years
+//  3. duration_value ASC
+//  4. submission_code ASC (deterministic tiebreak)
+//
+// Issue: m/paliad#128 — post-decision optional events (R.151/R.353
+// 1-month before R.118.4/R.220.1 2-month) were rendering in catalog
+// order instead of likely-sequence order. (t-paliad-296)
+func sortDeadlinesByDurationWithinTriggerGroup(
+	deadlines []UIDeadline,
+	ruleByID map[uuid.UUID]models.DeadlineRule,
+) {
+	if len(deadlines) < 2 {
+		return
+	}
+	n := len(deadlines)
+	i := 0
+	for i < n {
+		gid := triggerGroupKey(deadlines[i], ruleByID)
+		j := i + 1
+		for j < n && triggerGroupKey(deadlines[j], ruleByID) == gid {
+			j++
+		}
+		// Root rules (no parent and no trigger_event) get gid="root"
+		// and would otherwise collapse into one big run. Skip the sort
+		// for the "root" pseudo-group — each root rule represents its
+		// own anchor (SoC, oral hearing, decision …) and the
+		// proceeding-sequence order between them must be preserved.
+		if j-i > 1 && gid != "" {
+			chunk := deadlines[i:j]
+			sort.SliceStable(chunk, func(a, b int) bool {
+				return durationLessForSort(chunk[a], chunk[b], ruleByID)
+			})
+		}
+		i = j
+	}
+}
+
+// triggerGroupKey returns a string key identifying which trigger group
+// a deadline belongs to. Same key = same group = candidates for sort.
+// Empty string means "root" (no parent, no trigger_event) — used as a
+// sentinel by the caller to skip sorting roots against each other.
+func triggerGroupKey(d UIDeadline, ruleByID map[uuid.UUID]models.DeadlineRule) string {
+	rid, err := uuid.Parse(d.RuleID)
+	if err != nil {
+		return ""
+	}
+	r, ok := ruleByID[rid]
+	if !ok {
+		return ""
+	}
+	if r.ParentID != nil {
+		return "p:" + r.ParentID.String()
+	}
+	if r.TriggerEventID != nil {
+		return fmt.Sprintf("t:%d", *r.TriggerEventID)
+	}
+	return ""
+}
+
+// durationLessForSort compares two deadlines for the duration-ascending
+// sort. Court-set / conditional rows (no concrete date) sort LAST
+// regardless of duration — they don't fit the duration ladder.
+func durationLessForSort(
+	a, b UIDeadline,
+	ruleByID map[uuid.UUID]models.DeadlineRule,
+) bool {
+	aLast := a.IsCourtSet || a.IsConditional
+	bLast := b.IsCourtSet || b.IsConditional
+	if aLast != bLast {
+		return !aLast
+	}
+	if aLast && bLast {
+		return a.Code < b.Code
+	}
+
+	ra := lookupRuleFromDeadline(a, ruleByID)
+	rb := lookupRuleFromDeadline(b, ruleByID)
+
+	wa := durationUnitWeight(ra.DurationUnit)
+	wb := durationUnitWeight(rb.DurationUnit)
+	if wa != wb {
+		return wa < wb
+	}
+	if ra.DurationValue != rb.DurationValue {
+		return ra.DurationValue < rb.DurationValue
+	}
+	return a.Code < b.Code
+}
+
+func lookupRuleFromDeadline(
+	d UIDeadline,
+	ruleByID map[uuid.UUID]models.DeadlineRule,
+) models.DeadlineRule {
+	if d.RuleID == "" {
+		return models.DeadlineRule{}
+	}
+	rid, err := uuid.Parse(d.RuleID)
+	if err != nil {
+		return models.DeadlineRule{}
+	}
+	return ruleByID[rid]
+}
+
+// durationUnitWeight maps a duration unit to its sort weight so the
+// trigger-group sort can order shorter durations first. days and
+// working_days share weight 0 (both are sub-week granularities);
+// unknown units sort to the end so they're visible as a tail rather
+// than silently winning.
+func durationUnitWeight(unit string) int {
+	switch unit {
+	case "days", "working_days":
+		return 0
+	case "weeks":
+		return 1
+	case "months":
+		return 2
+	case "years":
+		return 3
+	}
+	return 4
+}
+
 // ErrUnknownRule is returned when CalculateRule can't resolve the
 // (proceedingCode, ruleLocalCode) pair or rule UUID to an active rule.
 var ErrUnknownRule = errors.New("unknown rule")

internal/services/fristenrechner_sort_test.go

@@ -0,0 +1,221 @@
+package services
+
+// Pure-function tests for the trigger-group duration sort introduced
+// by t-paliad-296 / m/paliad#128. No DB needed — feeds synthetic
+// UIDeadlines and a ruleByID map directly into the helper.
+
+import (
+	"testing"
+
+	"github.com/google/uuid"
+
+	"mgit.msbls.de/m/paliad/internal/models"
+)
+
+// makeRule is a tiny constructor for a synthetic rule with just the
+// fields the sort reads (parent_id, duration_value, duration_unit,
+// submission_code, trigger_event_id).
+func makeRule(t *testing.T, parent *uuid.UUID, code string, val int, unit string) (uuid.UUID, models.DeadlineRule) {
+	t.Helper()
+	id := uuid.New()
+	codeCopy := code
+	return id, models.DeadlineRule{
+		ID:             id,
+		ParentID:       parent,
+		SubmissionCode: &codeCopy,
+		DurationValue:  val,
+		DurationUnit:   unit,
+	}
+}
+
+func makeDeadline(id uuid.UUID, code string) UIDeadline {
+	return UIDeadline{
+		RuleID: id.String(),
+		Code:   code,
+	}
+}
+
+// TestSortDeadlinesByDurationWithinTriggerGroup_PostDecision is the
+// canonical scenario from m's report — four post-decision optional
+// events anchored on the same decision must render with 1-month rules
+// before 2-month rules.
+func TestSortDeadlinesByDurationWithinTriggerGroup_PostDecision(t *testing.T) {
+	decisionID := uuid.New()
+
+	// Catalog order matches mig 132 sequence_order: cons_orders(60),
+	// cost_app(70), rectification(70), appeal_spawn(80).
+	consOrdID, consOrdRule := makeRule(t, &decisionID, "upc.inf.cfi.cons_orders", 2, "months")
+	costAppID, costAppRule := makeRule(t, &decisionID, "upc.inf.cfi.cost_app", 1, "months")
+	rectID, rectRule := makeRule(t, &decisionID, "upc.inf.cfi.rectification", 1, "months")
+	appealID, appealRule := makeRule(t, &decisionID, "upc.inf.cfi.appeal_spawn", 2, "months")
+
+	ruleByID := map[uuid.UUID]models.DeadlineRule{
+		consOrdID: consOrdRule,
+		costAppID: costAppRule,
+		rectID:    rectRule,
+		appealID:  appealRule,
+	}
+
+	deadlines := []UIDeadline{
+		makeDeadline(consOrdID, "upc.inf.cfi.cons_orders"),
+		makeDeadline(costAppID, "upc.inf.cfi.cost_app"),
+		makeDeadline(rectID, "upc.inf.cfi.rectification"),
+		makeDeadline(appealID, "upc.inf.cfi.appeal_spawn"),
+	}
+
+	sortDeadlinesByDurationWithinTriggerGroup(deadlines, ruleByID)
+
+	// 1-month tier first (cost_app, rectification — alphabetical by
+	// submission_code), then 2-month tier (appeal_spawn, cons_orders
+	// — submission_code ASC tiebreak per spec).
+	want := []string{
+		"upc.inf.cfi.cost_app",
+		"upc.inf.cfi.rectification",
+		"upc.inf.cfi.appeal_spawn",
+		"upc.inf.cfi.cons_orders",
+	}
+	for i, w := range want {
+		if deadlines[i].Code != w {
+			t.Errorf("deadlines[%d].Code = %q, want %q", i, deadlines[i].Code, w)
+		}
+	}
+}
+
+// TestSortDeadlinesByDurationWithinTriggerGroup_UnitWeight asserts the
+// unit-weight ordering: days < weeks < months < years, with shorter
+// durations of the same unit winning their tier.
+func TestSortDeadlinesByDurationWithinTriggerGroup_UnitWeight(t *testing.T) {
+	parentID := uuid.New()
+
+	d14ID, d14Rule := makeRule(t, &parentID, "x.14days", 14, "days")
+	d2wID, d2wRule := makeRule(t, &parentID, "x.2weeks", 2, "weeks")
+	d1mID, d1mRule := makeRule(t, &parentID, "x.1month", 1, "months")
+	d6mID, d6mRule := makeRule(t, &parentID, "x.6months", 6, "months")
+	d1yID, d1yRule := makeRule(t, &parentID, "x.1year", 1, "years")
+
+	ruleByID := map[uuid.UUID]models.DeadlineRule{
+		d14ID: d14Rule, d2wID: d2wRule, d1mID: d1mRule, d6mID: d6mRule, d1yID: d1yRule,
+	}
+
+	deadlines := []UIDeadline{
+		makeDeadline(d6mID, "x.6months"),
+		makeDeadline(d1yID, "x.1year"),
+		makeDeadline(d2wID, "x.2weeks"),
+		makeDeadline(d14ID, "x.14days"),
+		makeDeadline(d1mID, "x.1month"),
+	}
+
+	sortDeadlinesByDurationWithinTriggerGroup(deadlines, ruleByID)
+
+	want := []string{"x.14days", "x.2weeks", "x.1month", "x.6months", "x.1year"}
+	for i, w := range want {
+		if deadlines[i].Code != w {
+			t.Errorf("deadlines[%d].Code = %q, want %q", i, deadlines[i].Code, w)
+		}
+	}
+}
+
+// TestSortDeadlinesByDurationWithinTriggerGroup_NoCrossGroupReorder
+// guards the hard rule: rules with different parents must keep their
+// relative position. Sorting only ever permutes adjacent same-parent
+// rows.
+func TestSortDeadlinesByDurationWithinTriggerGroup_NoCrossGroupReorder(t *testing.T) {
+	parentAID := uuid.New()
+	parentBID := uuid.New()
+
+	a3mID, a3mRule := makeRule(t, &parentAID, "ga.3months", 3, "months")
+	b1mID, b1mRule := makeRule(t, &parentBID, "gb.1month", 1, "months")
+	a14dID, a14dRule := makeRule(t, &parentAID, "ga.14days", 14, "days")
+	b2mID, b2mRule := makeRule(t, &parentBID, "gb.2months", 2, "months")
+
+	ruleByID := map[uuid.UUID]models.DeadlineRule{
+		a3mID: a3mRule, b1mID: b1mRule, a14dID: a14dRule, b2mID: b2mRule,
+	}
+
+	// Interleaved groups: A, B, A, B. Each group has one rule between
+	// each other group's rules — the consecutive-run walk should treat
+	// each as its own one-element run and not reorder anything.
+	deadlines := []UIDeadline{
+		makeDeadline(a3mID, "ga.3months"),
+		makeDeadline(b1mID, "gb.1month"),
+		makeDeadline(a14dID, "ga.14days"),
+		makeDeadline(b2mID, "gb.2months"),
+	}
+
+	sortDeadlinesByDurationWithinTriggerGroup(deadlines, ruleByID)
+
+	want := []string{"ga.3months", "gb.1month", "ga.14days", "gb.2months"}
+	for i, w := range want {
+		if deadlines[i].Code != w {
+			t.Errorf("deadlines[%d].Code = %q, want %q (interleaved groups must not reorder across)", i, deadlines[i].Code, w)
+		}
+	}
+}
+
+// TestSortDeadlinesByDurationWithinTriggerGroup_ConditionalLast asserts
+// that court-set / conditional rows (no concrete date in the duration
+// ladder) sort LAST within their group, regardless of their stated
+// duration value.
+func TestSortDeadlinesByDurationWithinTriggerGroup_ConditionalLast(t *testing.T) {
+	parentID := uuid.New()
+
+	dID, dRule := makeRule(t, &parentID, "x.duration", 2, "months")
+	cID, cRule := makeRule(t, &parentID, "x.conditional", 1, "months")
+	csID, csRule := makeRule(t, &parentID, "x.courtset", 1, "months")
+	d2ID, d2Rule := makeRule(t, &parentID, "x.short", 14, "days")
+
+	ruleByID := map[uuid.UUID]models.DeadlineRule{
+		dID: dRule, cID: cRule, csID: csRule, d2ID: d2Rule,
+	}
+
+	deadlines := []UIDeadline{
+		{RuleID: cID.String(), Code: "x.conditional", IsConditional: true},
+		{RuleID: dID.String(), Code: "x.duration"},
+		{RuleID: csID.String(), Code: "x.courtset", IsCourtSet: true},
+		{RuleID: d2ID.String(), Code: "x.short"},
+	}
+
+	sortDeadlinesByDurationWithinTriggerGroup(deadlines, ruleByID)
+
+	// Concrete rows first (sorted by duration): x.short (14d) then
+	// x.duration (2mo). Then the two no-date rows, tiebroken by code:
+	// x.conditional < x.courtset alphabetically.
+	want := []string{"x.short", "x.duration", "x.conditional", "x.courtset"}
+	for i, w := range want {
+		if deadlines[i].Code != w {
+			t.Errorf("deadlines[%d].Code = %q, want %q", i, deadlines[i].Code, w)
+		}
+	}
+}
+
+// TestSortDeadlinesByDurationWithinTriggerGroup_RootsNotMerged guards
+// the root-rule exception: top-level rules (parent_id=nil, no
+// trigger_event_id) must never be sorted against each other — they
+// represent distinct anchor points (SoC vs oral hearing vs decision)
+// whose proceeding-sequence order is non-negotiable.
+func TestSortDeadlinesByDurationWithinTriggerGroup_RootsNotMerged(t *testing.T) {
+	rootSoCID, rootSoCRule := makeRule(t, nil, "x.soc", 0, "months")
+	rootOralID, rootOralRule := makeRule(t, nil, "x.oral", 0, "months")
+	rootDecID, rootDecRule := makeRule(t, nil, "x.decision", 0, "months")
+
+	ruleByID := map[uuid.UUID]models.DeadlineRule{
+		rootSoCID: rootSoCRule, rootOralID: rootOralRule, rootDecID: rootDecRule,
+	}
+
+	deadlines := []UIDeadline{
+		makeDeadline(rootSoCID, "x.soc"),
+		makeDeadline(rootOralID, "x.oral"),
+		makeDeadline(rootDecID, "x.decision"),
+	}
+
+	sortDeadlinesByDurationWithinTriggerGroup(deadlines, ruleByID)
+
+	// Roots must keep their input order — they're not in the same
+	// trigger group as each other.
+	want := []string{"x.soc", "x.oral", "x.decision"}
+	for i, w := range want {
+		if deadlines[i].Code != w {
+			t.Errorf("deadlines[%d].Code = %q, want %q (roots must not be sorted against each other)", i, deadlines[i].Code, w)
+		}
+	}
+}