Implement linear task chains and recurring maintenance buckets

Backend, web timeline, and Android widget wiring for the last two
unimplemented items from doot-future-task-scheduling-ideas.

Chains: task_chains table + chain_id/chain_position/chain_unlocked on
native_tasks (migration 026), WIP-limit-1 advancement hooked into
CompleteNativeTask, locked tasks excluded from all date-based queries,
5 new /api/widget/chains* endpoints, an N/M position badge on web and
Android widget rows.

Buckets: maintenance_buckets table + bucket_id/bucket_state/
bucket_last_active_at on native_tasks (migration 027),
staleness-then-priority selection scoring, a new RunBucketCycleCheck
scheduler loop, 5 new endpoints including the distinct Defer action, a
Defer button on web and Android widget rows.

Also corrected stale "not yet approved" status headers on the two
already-shipped specs this work depended on (labels/projects, budgets/
availability) -- their headers were never updated after implementation.

Co-Authored-By: Claude Sonnet 5 <noreply@anthropic.com>
Claude-Session: https://claude.ai/code/session_01EZ7ikw2ukGJFTHE3bJS7zL

1 files changed, 94 insertions, 0 deletions

diff --git a/internal/handlers/defer_atom_test.go b/internal/handlers/defer_atom_test.go
new file mode 100644
index 0000000..1a626d5
--- /dev/null
+++ b/internal/handlers/defer_atom_test.go
@@ -0,0 +1,94 @@
+package handlers
+
+import (
+	"net/http"
+	"net/http/httptest"
+	"testing"
+	"time"
+
+	"task-dashboard/internal/config"
+	"task-dashboard/internal/models"
+)
+
+func TestHandleDeferAtom_ReturnsActiveBucketItemToDormant(t *testing.T) {
+	db, cleanup := setupTestDB(t)
+	defer cleanup()
+	h := &Handler{store: db, config: &config.Config{}}
+
+	// pick_n=1 plus a reserve item added after the cycle runs, so deferring
+	// task-1 backfills with the reserve rather than immediately re-picking
+	// task-1 itself (the only-item-in-pool case is a degenerate edge case
+	// covered at the store layer).
+	bucket, err := h.store.CreateBucket("Gutters", 30, 1)
+	if err != nil {
+		t.Fatal(err)
+	}
+	if err := h.store.CreateNativeTask(models.Task{ID: "task-1", Content: "Clean gutters", Priority: 1}); err != nil {
+		t.Fatal(err)
+	}
+	if err := h.store.AddBucketItem(bucket.ID, "task-1"); err != nil {
+		t.Fatal(err)
+	}
+	if _, err := h.store.RunBucketCycles(time.Now()); err != nil {
+		t.Fatal(err)
+	}
+	if err := h.store.CreateNativeTask(models.Task{ID: "reserve", Content: "reserve", Priority: 1}); err != nil {
+		t.Fatal(err)
+	}
+	if err := h.store.AddBucketItem(bucket.ID, "reserve"); err != nil {
+		t.Fatal(err)
+	}
+
+	req := httptest.NewRequest("POST", "/defer-atom", nil)
+	req.Form = map[string][]string{"id": {"task-1"}}
+	w := httptest.NewRecorder()
+	h.HandleDeferAtom(w, req)
+
+	if w.Code != http.StatusOK {
+		t.Fatalf("status = %d, want 200, body=%s", w.Code, w.Body.String())
+	}
+	if w.Header().Get("HX-Trigger") != "refresh-tasks" {
+		t.Errorf("HX-Trigger = %q, want refresh-tasks", w.Header().Get("HX-Trigger"))
+	}
+	updated, err := h.store.GetNativeTaskByID("task-1")
+	if err != nil {
+		t.Fatal(err)
+	}
+	if updated.BucketState != "dormant" {
+		t.Errorf("BucketState = %q, want dormant", updated.BucketState)
+	}
+}
+
+func TestHandleDeferAtom_MissingID_Returns400(t *testing.T) {
+	db, cleanup := setupTestDB(t)
+	defer cleanup()
+	h := &Handler{store: db, config: &config.Config{}}
+
+	req := httptest.NewRequest("POST", "/defer-atom", nil)
+	req.Form = map[string][]string{"id": {""}}
+	w := httptest.NewRecorder()
+	h.HandleDeferAtom(w, req)
+
+	if w.Code != http.StatusBadRequest {
+		t.Fatalf("status = %d, want 400", w.Code)
+	}
+}
+
+func TestHandleDeferAtom_NotABucketItem_Returns500(t *testing.T) {
+	db, cleanup := setupTestDB(t)
+	defer cleanup()
+	h := &Handler{store: db, config: &config.Config{}}
+
+	if err := h.store.CreateNativeTask(models.Task{ID: "task-1", Content: "Plain task", Priority: 1}); err != nil {
+		t.Fatal(err)
+	}
+
+	req := httptest.NewRequest("POST", "/defer-atom", nil)
+	req.Form = map[string][]string{"id": {"task-1"}}
+	w := httptest.NewRecorder()
+	h.HandleDeferAtom(w, req)
+
+	if w.Code != http.StatusInternalServerError {
+		t.Fatalf("status = %d, want 500", w.Code)
+	}
+}