Season view: filter the editor to a year (#54)

"Change the garlic bed to cucumbers this year" has a year in it, and pansy had
no notion of one — the editor showed whatever is currently planted, full stop.

The data has always supported seasons: plantings carry planted_at and
removed_at, and "clear bed" soft-removes rather than deleting. A season is a
date range over data that already exists. No schema change, and specifically no
seasons table — it would duplicate what the dates already say and create a
second source of truth about when something was in the ground.

?year=YYYY on /full returns every plop whose [planted_at, removed_at] interval
overlapped that calendar year, so garlic planted in October and pulled the
following July appears in BOTH years, which is what actually happened. Undated
plantings appear in every year: everything that predates this feature has a null
planted_at, and a rule that excluded them would empty every existing garden the
moment a year was selected. Without the param /full behaves exactly as before —
the existing tests pass unchanged, which was the point of doing it this way.

Widening to past plops means widening the referenced-plant lookup with it.
A plant pulled last July isn't active, but its plops still have to render with
the right icon and colour, so ListReferencedPlants takes an includeRemoved flag
that tracks the same switch.

A past season is READ-ONLY, gated at the single canEdit the palette, inspector,
nudging, placement and drag handles all key off. Editing the past by accident is
the failure mode this feature introduces, so the state is stated in a banner
rather than implied by a dropdown you set a while ago, with the way back to the
live garden next to it.

The season is a separate query under its own key. The optimistic mutations all
patch gardenFullKey(gardenId); folding a year into that key would let them write
into whichever season happened to be on screen. Read-only views never need that
machinery, and keeping them out of it means they can't accidentally join it.

The year selector offers only years the garden holds data for, plus the current
one. A free numeric field invites a typo, and a typo'd year produces a
confidently empty garden that reads as data loss rather than a mistake — the
server bounds the year for the same reason.

Closes #54

Co-Authored-By: Claude Opus 4.8 (1M context) <[email protected]>
Claude-Session: https://claude.ai/code/session_01H3zbym8Doka2d7D48maSgZ

internal/api/objects.go

@@ -4,6 +4,7 @@ import (
 	"encoding/json"
 	"errors"
 	"net/http"
+	"strconv"
 
 	"github.com/gin-gonic/gin"
 
@@ -171,15 +172,47 @@ func (h *handlers) deleteObject(c *gin.Context) {
 	c.Status(http.StatusNoContent)
 }
 
+// getGardenFull serves the editor's one-shot load. ?year=YYYY switches it to the
+// season view: every plop whose time in the ground overlapped that calendar
+// year, INCLUDING ones since removed.
+//
+// Undated plantings are returned for every year. Everything planted before this
+// feature existed has a null planted_at, so excluding them would empty every
+// garden the moment a year was picked — technically defensible, useless in
+// practice. Without the param the behaviour is exactly what it has always been.
 func (h *handlers) getGardenFull(c *gin.Context) {
 	gardenID, ok := parseIDParam(c, "id")
 	if !ok {
 		return
 	}
-	full, err := h.svc.GardenFull(c.Request.Context(), mustActor(c).ID, gardenID)
+	var year *int
+	if raw := c.Query("year"); raw != "" {
+		y, err := strconv.Atoi(raw)
+		if err != nil {
+			writeAPIError(c, http.StatusBadRequest, "INVALID_INPUT", "year must be a four-digit year")
+			return
+		}
+		year = &y
+	}
+	full, err := h.svc.GardenFull(c.Request.Context(), mustActor(c).ID, gardenID, year)
 	if err != nil {
 		writeServiceError(c, err)
 		return
 	}
 	c.JSON(http.StatusOK, full)
 }
+
+// getGardenYears lists the years this garden has planting data for, so the year
+// selector can offer only years that hold something.
+func (h *handlers) getGardenYears(c *gin.Context) {
+	gardenID, ok := parseIDParam(c, "id")
+	if !ok {
+		return
+	}
+	years, err := h.svc.GardenYears(c.Request.Context(), mustActor(c).ID, gardenID)
+	if err != nil {
+		writeServiceError(c, err)
+		return
+	}
+	c.JSON(http.StatusOK, gin.H{"years": years})
+}