feat(discover): time-boxed suggestion snooze, server side — #2374

Migration 0049 adds suggestion_snoozes(user_id, candidate_mbid,
candidate_name, snoozed_until), and SuggestArtistsForUser excludes rows
whose snooze hasn't expired.

This is NOT a dislike. Rule #101 forbids a "Not for me" / thumbs-down
UI; a snooze is the approved shape instead because it records no verdict
on the music, expires on its own (~90d), and never reaches the taste
profile. It's acquisition triage — "not right now" — so the filter sits
at the candidate stage rather than in the score, where it would become a
ranking signal by the back door.

Per-user throughout (rule #47): one household member parking a candidate
leaves everyone else's deck untouched.

candidate_name is denormalized because suggestions are out-of-library by
definition — there is no artists row to resolve a display name from, and
the un-snooze list has to show something. That list is why GET
/discover/snoozes exists at all: a parked candidate is by definition
absent from the deck, so without it the DELETE would be unreachable.

Also fixes a hole in the codegen check from #2380: `git diff` ignores
untracked paths, so a brand-new generated file would have passed it
silently. `git add -N` first. This commit is the first to add one.

Endpoints:
  POST   /api/discover/suggestions/{mbid}/snooze  (body: name, days)
  DELETE /api/discover/suggestions/{mbid}/snooze
  GET    /api/discover/snoozes

UI lands in slice 4 (#2375) before any of this merges — rule #27.

Co-Authored-By: Claude Opus 5 (1M context) <noreply@anthropic.com>

internal/db/dbq/suggestion_snoozes.sql.go

@@ -0,0 +1,126 @@
+// Code generated by sqlc. DO NOT EDIT.
+// versions:
+//   sqlc v1.31.1
+// source: suggestion_snoozes.sql
+
+package dbq
+
+import (
+	"context"
+
+	"github.com/jackc/pgx/v5/pgtype"
+)
+
+const gcDeleteExpiredSuggestionSnoozes = `-- name: GcDeleteExpiredSuggestionSnoozes :execrows
+DELETE FROM suggestion_snoozes WHERE snoozed_until < now()
+`
+
+// Keeps the table from growing without bound. Every read already filters on
+// snoozed_until > now(), so deleting an expired row changes no behaviour —
+// this is purely reclamation.
+func (q *Queries) GcDeleteExpiredSuggestionSnoozes(ctx context.Context) (int64, error) {
+	result, err := q.db.Exec(ctx, gcDeleteExpiredSuggestionSnoozes)
+	if err != nil {
+		return 0, err
+	}
+	return result.RowsAffected(), nil
+}
+
+const listActiveSuggestionSnoozes = `-- name: ListActiveSuggestionSnoozes :many
+SELECT candidate_mbid, candidate_name, snoozed_until, created_at
+  FROM suggestion_snoozes
+ WHERE user_id = $1 AND snoozed_until > now()
+ ORDER BY snoozed_until, candidate_mbid
+`
+
+type ListActiveSuggestionSnoozesRow struct {
+	CandidateMbid string
+	CandidateName string
+	SnoozedUntil  pgtype.Timestamptz
+	CreatedAt     pgtype.Timestamptz
+}
+
+// Backs the manage / un-snooze surface. Expired rows are filtered HERE
+// rather than left to the sweeper: gc runs on an hourly tick, so a row can
+// outlive its expiry by up to a tick and must not read as still-snoozed in
+// the meantime.
+func (q *Queries) ListActiveSuggestionSnoozes(ctx context.Context, userID pgtype.UUID) ([]ListActiveSuggestionSnoozesRow, error) {
+	rows, err := q.db.Query(ctx, listActiveSuggestionSnoozes, userID)
+	if err != nil {
+		return nil, err
+	}
+	defer rows.Close()
+	var items []ListActiveSuggestionSnoozesRow
+	for rows.Next() {
+		var i ListActiveSuggestionSnoozesRow
+		if err := rows.Scan(
+			&i.CandidateMbid,
+			&i.CandidateName,
+			&i.SnoozedUntil,
+			&i.CreatedAt,
+		); err != nil {
+			return nil, err
+		}
+		items = append(items, i)
+	}
+	if err := rows.Err(); err != nil {
+		return nil, err
+	}
+	return items, nil
+}
+
+const snoozeSuggestion = `-- name: SnoozeSuggestion :exec
+
+INSERT INTO suggestion_snoozes (user_id, candidate_mbid, candidate_name, snoozed_until)
+VALUES ($1, $2, $3, now() + ($4::float8 * INTERVAL '1 day'))
+ON CONFLICT (user_id, candidate_mbid) DO UPDATE
+   SET snoozed_until  = EXCLUDED.snoozed_until,
+       candidate_name = EXCLUDED.candidate_name
+`
+
+type SnoozeSuggestionParams struct {
+	UserID        pgtype.UUID
+	CandidateMbid string
+	CandidateName string
+	Column4       float64
+}
+
+// Time-boxed "not right now" on a Discover artist suggestion (#2374).
+//
+// See 0049_suggestion_snoozes.up.sql for why this is a snooze and not a
+// dismissal: it records no verdict on the music, expires on its own, and
+// must never reach the taste profile. Nothing in internal/taste may read
+// this table.
+// Upsert, so re-snoozing an already-snoozed candidate EXTENDS it instead of
+// erroring on the PK. The name is refreshed too — a later suggestion may
+// carry a corrected spelling from the similarity feed.
+// $1=user_id, $2=candidate_mbid, $3=candidate_name, $4=duration in days.
+func (q *Queries) SnoozeSuggestion(ctx context.Context, arg SnoozeSuggestionParams) error {
+	_, err := q.db.Exec(ctx, snoozeSuggestion,
+		arg.UserID,
+		arg.CandidateMbid,
+		arg.CandidateName,
+		arg.Column4,
+	)
+	return err
+}
+
+const unsnoozeSuggestion = `-- name: UnsnoozeSuggestion :execrows
+DELETE FROM suggestion_snoozes
+ WHERE user_id = $1 AND candidate_mbid = $2
+`
+
+type UnsnoozeSuggestionParams struct {
+	UserID        pgtype.UUID
+	CandidateMbid string
+}
+
+// Row count is returned so the handler can 404 an MBID that was never
+// snoozed rather than reporting success for a no-op.
+func (q *Queries) UnsnoozeSuggestion(ctx context.Context, arg UnsnoozeSuggestionParams) (int64, error) {
+	result, err := q.db.Exec(ctx, unsnoozeSuggestion, arg.UserID, arg.CandidateMbid)
+	if err != nil {
+		return 0, err
+	}
+	return result.RowsAffected(), nil
+}