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, 161 insertions, 0 deletions

diff --git a/internal/handlers/chains_test.go b/internal/handlers/chains_test.go
new file mode 100644
index 0000000..0ebcc7a
--- /dev/null
+++ b/internal/handlers/chains_test.go
@@ -0,0 +1,161 @@
+package handlers
+
+import (
+	"context"
+	"encoding/json"
+	"net/http"
+	"net/http/httptest"
+	"strings"
+	"testing"
+
+	"github.com/go-chi/chi/v5"
+)
+
+func withURLParam(req *http.Request, key, value string) *http.Request {
+	rctx := chi.NewRouteContext()
+	rctx.URLParams.Add(key, value)
+	return req.WithContext(context.WithValue(req.Context(), chi.RouteCtxKey, rctx))
+}
+
+func TestHandleWidgetChainsCreate_CreatesChain(t *testing.T) {
+	db, cleanup := setupTestDB(t)
+	defer cleanup()
+	h := &Handler{store: db}
+
+	body := `{"name":"Ham Radio Track","tasks":["Study Technician","Pass exam"]}`
+	req := httptest.NewRequest("POST", "/api/widget/chains", strings.NewReader(body))
+	w := httptest.NewRecorder()
+	h.HandleWidgetChainsCreate(w, req)
+
+	if w.Code != http.StatusOK {
+		t.Fatalf("status = %d, want 200, body=%s", w.Code, w.Body.String())
+	}
+	var resp chainCreateResponse
+	if err := json.NewDecoder(w.Body).Decode(&resp); err != nil {
+		t.Fatal(err)
+	}
+	if resp.ID == "" {
+		t.Fatal("expected a generated chain id")
+	}
+
+	tasks, err := h.store.GetChainTasks(resp.ID)
+	if err != nil {
+		t.Fatal(err)
+	}
+	if len(tasks) != 2 {
+		t.Fatalf("len(tasks) = %d, want 2", len(tasks))
+	}
+}
+
+func TestHandleWidgetChainsCreate_EmptyTasks_Returns400(t *testing.T) {
+	db, cleanup := setupTestDB(t)
+	defer cleanup()
+	h := &Handler{store: db}
+
+	body := `{"name":"Empty","tasks":[]}`
+	req := httptest.NewRequest("POST", "/api/widget/chains", strings.NewReader(body))
+	w := httptest.NewRecorder()
+	h.HandleWidgetChainsCreate(w, req)
+
+	if w.Code != http.StatusBadRequest {
+		t.Fatalf("status = %d, want 400", w.Code)
+	}
+}
+
+func TestHandleWidgetChainGet_ReturnsChainAndTasks(t *testing.T) {
+	db, cleanup := setupTestDB(t)
+	defer cleanup()
+	h := &Handler{store: db}
+
+	chain, err := h.store.CreateChain("Track", []string{"Step 1", "Step 2"})
+	if err != nil {
+		t.Fatal(err)
+	}
+
+	req := withURLParam(httptest.NewRequest("GET", "/api/widget/chains/"+chain.ID, nil), "id", chain.ID)
+	w := httptest.NewRecorder()
+	h.HandleWidgetChainGet(w, req)
+
+	if w.Code != http.StatusOK {
+		t.Fatalf("status = %d, want 200, body=%s", w.Code, w.Body.String())
+	}
+	var resp chainGetResponse
+	if err := json.NewDecoder(w.Body).Decode(&resp); err != nil {
+		t.Fatal(err)
+	}
+	if len(resp.Tasks) != 2 || resp.Chain.ID != chain.ID {
+		t.Errorf("resp = %+v", resp)
+	}
+}
+
+func TestHandleWidgetChainGet_UnknownID_Returns404(t *testing.T) {
+	db, cleanup := setupTestDB(t)
+	defer cleanup()
+	h := &Handler{store: db}
+
+	req := withURLParam(httptest.NewRequest("GET", "/api/widget/chains/nope", nil), "id", "nope")
+	w := httptest.NewRecorder()
+	h.HandleWidgetChainGet(w, req)
+
+	if w.Code != http.StatusNotFound {
+		t.Fatalf("status = %d, want 404", w.Code)
+	}
+}
+
+func TestHandleWidgetChainsPauseResumeAbandon(t *testing.T) {
+	db, cleanup := setupTestDB(t)
+	defer cleanup()
+	h := &Handler{store: db}
+
+	chain, err := h.store.CreateChain("Track", []string{"Step 1", "Step 2"})
+	if err != nil {
+		t.Fatal(err)
+	}
+
+	pauseReq := withURLParam(httptest.NewRequest("POST", "/api/widget/chains/"+chain.ID+"/pause", nil), "id", chain.ID)
+	w := httptest.NewRecorder()
+	h.HandleWidgetChainsPause(w, pauseReq)
+	if w.Code != http.StatusOK {
+		t.Fatalf("pause status = %d, want 200", w.Code)
+	}
+	paused, err := h.store.GetChain(chain.ID)
+	if err != nil || paused.Status != "paused" {
+		t.Fatalf("chain after pause = %+v, err=%v", paused, err)
+	}
+
+	resumeReq := withURLParam(httptest.NewRequest("POST", "/api/widget/chains/"+chain.ID+"/resume", nil), "id", chain.ID)
+	w = httptest.NewRecorder()
+	h.HandleWidgetChainsResume(w, resumeReq)
+	if w.Code != http.StatusOK {
+		t.Fatalf("resume status = %d, want 200", w.Code)
+	}
+	resumed, err := h.store.GetChain(chain.ID)
+	if err != nil || resumed.Status != "active" {
+		t.Fatalf("chain after resume = %+v, err=%v", resumed, err)
+	}
+
+	abandonReq := withURLParam(httptest.NewRequest("POST", "/api/widget/chains/"+chain.ID+"/abandon", nil), "id", chain.ID)
+	w = httptest.NewRecorder()
+	h.HandleWidgetChainsAbandon(w, abandonReq)
+	if w.Code != http.StatusOK {
+		t.Fatalf("abandon status = %d, want 200", w.Code)
+	}
+	abandoned, err := h.store.GetChain(chain.ID)
+	if err != nil || abandoned.Status != "abandoned" {
+		t.Fatalf("chain after abandon = %+v, err=%v", abandoned, err)
+	}
+}
+
+func TestHandleWidgetChainsPause_UnknownID_Returns404(t *testing.T) {
+	db, cleanup := setupTestDB(t)
+	defer cleanup()
+	h := &Handler{store: db}
+
+	req := withURLParam(httptest.NewRequest("POST", "/api/widget/chains/nope/pause", nil), "id", "nope")
+	w := httptest.NewRecorder()
+	h.HandleWidgetChainsPause(w, req)
+
+	if w.Code != http.StatusNotFound {
+		t.Fatalf("status = %d, want 404", w.Code)
+	}
+}