Add plan service and weekly plan API

Add internal/plan: a draft_week job that drafts the week through the
harness from every Regular and the Quest log dinners no other current or
later plan holds, given the household context and last week's dinners,
and stores it as the week's plan; plan reads with the week label, is_new
and each crock-pot dinner's start_by (dinner time minus minutes_total,
computed on read); and day swaps that recompute is_new and move a synced
plan to changed. Drafting over a synced or changed plan needs confirm, at
enqueue and again when the job stores the week; a redraft keeps each
day's calendar event id.

Serve GET /api/v1/plans/{weekStart}, POST /api/v1/plans/{weekStart}/draft
(202 {job_id}, single-flight per week) and PUT
/api/v1/plans/{weekStart}/days/{date}; a weekStart that is not a Monday
is 400 invalid_week.

Maestro task ea48e650-d510-49cc-8485-0f07174ee731.

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

internal/plan/draft.go

@@ -0,0 +1,185 @@
+package plan
+
+import (
+	"context"
+	"database/sql"
+	"encoding/json"
+	"errors"
+	"fmt"
+	"time"
+
+	"code.cubecraftlabs.com/Maniacs_Mansion/Meal-Quest/internal/ai/harness"
+	"code.cubecraftlabs.com/Maniacs_Mansion/Meal-Quest/internal/ai/skills"
+	"code.cubecraftlabs.com/Maniacs_Mansion/Meal-Quest/internal/db"
+	"code.cubecraftlabs.com/Maniacs_Mansion/Meal-Quest/internal/dinners"
+	"code.cubecraftlabs.com/Maniacs_Mansion/Meal-Quest/internal/household"
+	"code.cubecraftlabs.com/Maniacs_Mansion/Meal-Quest/internal/jobs"
+	"code.cubecraftlabs.com/Maniacs_Mansion/Meal-Quest/internal/store"
+)
+
+// DraftJob is the KindDraftWeek payload: the week to draft, and whether
+// the household confirmed drafting over a synced or changed plan.
+type DraftJob struct {
+	WeekStart string `json:"week_start"`
+	Confirm   bool   `json:"confirm"`
+}
+
+// draftResult is the KindDraftWeek result: the week drafted and its plan.
+type draftResult struct {
+	WeekStart string `json:"week_start"`
+	PlanID    string `json:"plan_id"`
+}
+
+func (r draftResult) PublicJSON() ([]byte, error) { return json.Marshal(r) }
+
+// runDraft drafts the week p.WeekStart: draft_week plans it from the
+// Regulars and the Quest log dinners no other current or later plan has,
+// given the household context and last week's dinners, and the draft is
+// stored as the week's plan. A pool under seven dinners fails with
+// ReasonNotEnoughDinners and draft_week failing with ReasonAIFailed; no
+// week is made up instead.
+func (s *Service) runDraft(ctx context.Context, p DraftJob, _ func(draftResult) error) (draftResult, error) {
+	weekStart, err := ParseWeekStart(p.WeekStart)
+	if err != nil {
+		return draftResult{}, fmt.Errorf("plan: draft: %w", err)
+	}
+	in, err := s.request(ctx, weekStart)
+	if err != nil {
+		return draftResult{}, err
+	}
+	week, err := s.draft(ctx, household.PeriodKey(weekStart), in)
+	if err != nil {
+		if ctx.Err() != nil {
+			return draftResult{}, ctx.Err()
+		}
+		var few *skills.NotEnoughDinnersError
+		if errors.As(err, &few) {
+			return draftResult{}, &jobs.Failure{Code: ReasonNotEnoughDinners}
+		}
+		// Only the code is logged: the error may quote a model's response.
+		s.logger.InfoContext(ctx, "week draft failed", "week_start", p.WeekStart, "reason", ReasonAIFailed)
+		return draftResult{}, &jobs.Failure{Code: ReasonAIFailed}
+	}
+	for _, w := range week.Warnings {
+		s.logger.InfoContext(ctx, "week draft warning", "week_start", p.WeekStart, "warning", w)
+	}
+	planID, err := s.storeDraft(ctx, weekStart, p.Confirm, week)
+	if err != nil {
+		return draftResult{}, err
+	}
+	return draftResult{WeekStart: p.WeekStart, PlanID: planID}, nil
+}
+
+// request reads what draft_week is given for the week starting weekStart:
+// the household context, the pool, last week's dinners and the dinner
+// time.
+func (s *Service) request(ctx context.Context, weekStart store.LocalDate) (skills.WeekRequest, error) {
+	hctx, err := harness.BuildContext(ctx, s.st, time.Now(), ContextBudget)
+	if err != nil {
+		return skills.WeekRequest{}, fmt.Errorf("plan: %w", err)
+	}
+	q := db.New(s.st.Reader)
+	settings, err := q.GetHouseholdSettings(ctx)
+	if err != nil {
+		return skills.WeekRequest{}, fmt.Errorf("plan: read household settings: %w", err)
+	}
+	thisWeek := household.WeekStart(hctx.Today)
+	rows, err := q.ListDraftPool(ctx, db.ListDraftPoolParams{FromWeekStart: thisWeek.String(), WeekStart: weekStart.String()})
+	if err != nil {
+		return skills.WeekRequest{}, fmt.Errorf("plan: list draft pool: %w", err)
+	}
+	pool := make([]skills.Candidate, len(rows))
+	for i, d := range rows {
+		kind := skills.KindRegular
+		if d.Status == dinners.StatusQuestLog {
+			kind = skills.KindQuestLog
+		}
+		pool[i] = skills.Candidate{ID: d.ID, Name: d.Name, Kind: kind, Method: d.Method.String, Minutes: int(d.MinutesTotal.Int64)}
+	}
+	last, err := q.ListWeekPlanDinnerIDs(ctx, addDays(weekStart, -7).String())
+	if err != nil {
+		return skills.WeekRequest{}, fmt.Errorf("plan: list last week's dinners: %w", err)
+	}
+	lastWeek := []string{}
+	for _, id := range last {
+		lastWeek = append(lastWeek, id.String)
+	}
+	return skills.WeekRequest{
+		Context:    hctx,
+		WeekStart:  weekStart,
+		Pool:       pool,
+		LastWeek:   lastWeek,
+		DinnerTime: settings.DinnerTime,
+	}, nil
+}
+
+// storeDraft stores week as the plan of the week starting weekStart in one
+// transaction and returns the plan's id. A new plan is draft. A draft
+// replaces the days of an existing plan, keeping each day's calendar
+// event id; a draft plan stays draft and a synced or changed one becomes
+// changed, since Calendar no longer shows it. A plan synced since the
+// draft was asked for without confirm is left as it is, failing with
+// ReasonConfirmRequired.
+func (s *Service) storeDraft(ctx context.Context, weekStart store.LocalDate, confirm bool, week skills.Week) (string, error) {
+	var planID string
+	err := s.st.WithTx(ctx, func(tx *sql.Tx) error {
+		q := db.New(tx)
+		now := store.Now().String()
+		note := sql.NullString{String: week.Note, Valid: week.Note != ""}
+		cur, err := q.GetWeekPlan(ctx, weekStart.String())
+		switch {
+		case errors.Is(err, sql.ErrNoRows):
+			planID = store.NewID()
+			if err := q.CreateWeekPlan(ctx, db.CreateWeekPlanParams{
+				ID:        planID,
+				WeekStart: weekStart.String(),
+				AiNote:    note,
+				CreatedAt: now,
+				UpdatedAt: now,
+			}); err != nil {
+				return fmt.Errorf("plan: create week %s: %w", weekStart, err)
+			}
+		case err != nil:
+			return fmt.Errorf("plan: read week %s: %w", weekStart, err)
+		case cur.Status != StatusDraft && !confirm:
+			return &jobs.Failure{Code: ReasonConfirmRequired}
+		default:
+			planID = cur.ID
+			status := StatusDraft
+			if cur.Status != StatusDraft {
+				status = StatusChanged
+			}
+			if err := q.RedraftWeekPlan(ctx, db.RedraftWeekPlanParams{Status: status, AiNote: note, UpdatedAt: now, ID: cur.ID}); err != nil {
+				return fmt.Errorf("plan: redraft %s: %w", cur.ID, err)
+			}
+		}
+		for _, d := range week.Days {
+			isNew := int64(0)
+			if d.IsNew {
+				isNew = 1
+			}
+			if err := q.PutPlanDay(ctx, db.PutPlanDayParams{
+				ID:        store.NewID(),
+				PlanID:    planID,
+				Date:      d.Date,
+				DinnerID:  sql.NullString{String: d.DinnerID, Valid: true},
+				IsNew:     isNew,
+				CreatedAt: now,
+				UpdatedAt: now,
+			}); err != nil {
+				return fmt.Errorf("plan: put %s of %s: %w", d.Date, planID, err)
+			}
+		}
+		return nil
+	})
+	if err != nil {
+		return "", err
+	}
+	return planID, nil
+}
+
+// addDays returns d plus n days.
+func addDays(d store.LocalDate, n int) store.LocalDate {
+	y, m, day := d.Date()
+	return store.LocalDateOf(time.Date(y, m, day+n, 0, 0, 0, 0, time.UTC))
+}