fix(api): do the things the API says yes to

Three reports from somebody driving the app through the MCP connector,
all the same shape: an argument accepted, an OK returned, and nothing
done.

**project_id on an update never moved the task.** Both the REST handler
and the MCP tool read it, both checked the caller's rights on the
destination — which reads as "understood" — and then neither passed it
on, because store.TaskUpdate has no such field: a project change is a
move, since sort_order is per project. So the task stayed where it was
and the answer said OK. Moving a task between projects was impossible
except by creating it again and closing the old one, which is what the
person ended up doing. Both paths now go through one helper, so they
cannot drift apart again.

**An unknown #project vanished without a word.** The parser reads
"#3Dekoration" correctly; the lookup then fails, the task goes to the
Inbox, and the name is gone from the title with nothing anywhere saying
why. Still not an error — a thought should not be thrown away over a typo
— but quick-add now returns unknown_project, and the MCP tool returns a
note written for a model to relay. The old behaviour was kind in the web
interface, where you see the row appear in the wrong place and fix it. In
a chat nobody sees the row.

**Sub-tasks were unreachable over MCP.** create_task had no parent_id,
though the REST API has had it all along, so importing a parent with
seven children produced eight unrelated tasks with the parent's name
prefixed onto each. A sub-task joins its parent's project — the two
cannot disagree — and a second level is refused rather than silently
flattened.

Co-Authored-By: Claude Opus 5 <noreply@anthropic.com>

docs/openapi.yaml

@@ -533,7 +533,11 @@ paths:
                   type: string
                   description: Where it goes when the text names no project.
       responses:
-        "201": { $ref: "#/components/responses/Task" }
+        "201":
+          description: Created
+          content:
+            application/json:
+              schema: { $ref: "#/components/schemas/QuickAddResult" }
         "422": { $ref: "#/components/responses/Validation" }
 
   /api/v1/tasks/quick-add/preview:
@@ -2135,7 +2139,12 @@ components:
     TaskInput:
       type: object
       properties:
-        project_id: { type: string, description: "Omitted on create, the task goes to the Inbox." }
+        project_id:
+          type: string
+          description: |
+            Omitted on create, the task goes to the Inbox. On update it moves the
+            task — which needs editor rights on the destination.
+
         section_id: { type: string }
         parent_id: { type: string }
         content: { type: string }
@@ -2151,6 +2160,19 @@ components:
           items: { type: string }
         sort_order: { type: number }
 
+    QuickAddResult:
+      allOf:
+        - $ref: "#/components/schemas/Task"
+        - type: object
+          properties:
+            unknown_project:
+              type: string
+              description: |
+                Present when the text named a `#project` that does not exist. The
+                task is still created, in the Inbox — a thought is not thrown away
+                over a typo — but the caller is told, because the alternative is
+                that the name vanishes from the title and nothing says why.
+
     ParsedTask:
       type: object
       description: What the quick-add parser made of a line.

internal/httpapi/integrations_test.go

@@ -983,3 +983,173 @@ func TestWellKnownCalDAVStillRedirects(t *testing.T) {
 		t.Error("CalDAV discovery was caught by the well-known rule")
 	}
 }
+
+// --- what the API accepts, it must actually do -------------------------------------
+
+// project_id on an update used to be validated and then dropped: the destination
+// was permission-checked, which reads as "understood", and the task never moved
+// while the answer said OK. Both the REST path and the MCP tool did it.
+func TestUpdateMovesTheTaskToAnotherProject(t *testing.T) {
+	ts := newTestServer(t)
+	ts.bootstrap(t)
+
+	_, project := ts.do(t, "POST", "/api/v1/projects", map[string]string{"name": "Firma"})
+	projectID := project["id"].(string)
+
+	_, task := ts.do(t, "POST", "/api/v1/tasks", map[string]any{"content": "betal moms"})
+	taskID := task["id"].(string)
+	if task["project_id"] == projectID {
+		t.Fatal("the task started in the destination; the test proves nothing")
+	}
+
+	resp, updated := ts.do(t, "PATCH", "/api/v1/tasks/"+taskID,
+		map[string]any{"project_id": projectID})
+	if resp.StatusCode != http.StatusOK {
+		t.Fatalf("patch: status %d, body %v", resp.StatusCode, updated)
+	}
+	if updated["project_id"] != projectID {
+		t.Errorf("project_id = %v, want %v — the move was accepted and not made",
+			updated["project_id"], projectID)
+	}
+
+	// And it really is there, not merely reported as there.
+	_, reread := ts.do(t, "GET", "/api/v1/tasks/"+taskID, nil)
+	if reread["project_id"] != projectID {
+		t.Errorf("after re-reading, project_id = %v", reread["project_id"])
+	}
+}
+
+func TestMCPUpdateMovesTheTaskToAnotherProject(t *testing.T) {
+	ts := newTestServer(t)
+	ts.bootstrap(t)
+
+	_, project := ts.do(t, "POST", "/api/v1/projects", map[string]string{"name": "Firma"})
+	projectID := project["id"].(string)
+
+	created := ts.callTool(t, "create_task", map[string]any{"text": "betal moms"})
+	taskID := created["id"].(string)
+
+	moved := ts.callTool(t, "update_task", map[string]any{
+		"task_id": taskID, "project_id": projectID,
+	})
+	if moved["project_id"] != projectID {
+		t.Errorf("project_id = %v, want %v", moved["project_id"], projectID)
+	}
+}
+
+// A project you cannot write to is refused rather than quietly ignored.
+func TestUpdateRefusesAProjectYouCannotWriteTo(t *testing.T) {
+	ts := newTestServer(t)
+	ts.bootstrap(t)
+
+	other := ts.newUser(t, "anden@example.dk", "Anden")
+	_, theirs := other.do(t, "POST", "/api/v1/projects", map[string]string{"name": "Deres"})
+
+	_, task := ts.do(t, "POST", "/api/v1/tasks", map[string]any{"content": "min opgave"})
+	taskID := task["id"].(string)
+	mine := task["project_id"]
+
+	resp, _ := ts.do(t, "PATCH", "/api/v1/tasks/"+taskID,
+		map[string]any{"project_id": theirs["id"]})
+	if resp.StatusCode != http.StatusNotFound {
+		t.Errorf("status %d, want 404", resp.StatusCode)
+	}
+
+	_, reread := ts.do(t, "GET", "/api/v1/tasks/"+taskID, nil)
+	if reread["project_id"] != mine {
+		t.Error("the task moved into somebody else's project")
+	}
+}
+
+// An unknown #project is still not an error — the thought is kept rather than
+// thrown away over a typo — but it is no longer silent. It used to vanish from
+// the title while the task went to the Inbox, with nothing saying why.
+func TestQuickAddSaysWhenTheProjectDoesNotExist(t *testing.T) {
+	ts := newTestServer(t)
+	ts.bootstrap(t)
+
+	resp, body := ts.do(t, "POST", "/api/v1/tasks/quick-add",
+		map[string]any{"text": "Lav plakat #3Dekoration"})
+	if resp.StatusCode != http.StatusCreated {
+		t.Fatalf("status %d, want 201 — the task should still be created", resp.StatusCode)
+	}
+	if body["unknown_project"] != "3Dekoration" {
+		t.Errorf("unknown_project = %v, want %q", body["unknown_project"], "3Dekoration")
+	}
+	if body["content"] != "Lav plakat" {
+		t.Errorf("content = %v", body["content"])
+	}
+}
+
+func TestQuickAddSaysNothingWhenTheProjectExists(t *testing.T) {
+	ts := newTestServer(t)
+	ts.bootstrap(t)
+	ts.do(t, "POST", "/api/v1/projects", map[string]string{"name": "Dekoration"})
+
+	_, body := ts.do(t, "POST", "/api/v1/tasks/quick-add",
+		map[string]any{"text": "Lav plakat #Dekoration"})
+	if _, present := body["unknown_project"]; present {
+		t.Errorf("reported an unknown project for one that exists: %v", body)
+	}
+}
+
+func TestMCPCreateSaysWhenTheProjectDoesNotExist(t *testing.T) {
+	ts := newTestServer(t)
+	ts.bootstrap(t)
+
+	created := ts.callTool(t, "create_task", map[string]any{"text": "Lav plakat #3Dekoration"})
+	note, _ := created["note"].(string)
+	if !strings.Contains(note, "3Dekoration") {
+		t.Errorf("note = %q, want it to name the project that does not exist", note)
+	}
+}
+
+// Sub-tasks were unreachable over MCP: create_task had no parent_id, so a parent
+// with seven children arrived as eight unrelated tasks.
+func TestMCPCreateMakesSubtasks(t *testing.T) {
+	ts := newTestServer(t)
+	ts.bootstrap(t)
+
+	_, project := ts.do(t, "POST", "/api/v1/projects", map[string]string{"name": "Firma"})
+	parent := ts.callTool(t, "create_task", map[string]any{
+		"content": "Runen v2", "project_id": project["id"],
+	})
+	parentID := parent["id"].(string)
+
+	child := ts.callTool(t, "create_task", map[string]any{
+		"content": "Tegn ikonet", "parent_id": parentID,
+	})
+	if child["parent_id"] != parentID {
+		t.Errorf("parent_id = %v, want %v", child["parent_id"], parentID)
+	}
+	// A sub-task joins its parent's project whatever else was asked for.
+	if child["project_id"] != project["id"] {
+		t.Errorf("project_id = %v, want the parent's %v", child["project_id"], project["id"])
+	}
+
+	_, listed := ts.do(t, "GET", "/api/v1/tasks?parent_id="+parentID, nil)
+	if tasks, _ := listed["tasks"].([]any); len(tasks) != 1 {
+		t.Errorf("the parent has %d sub-tasks, want 1", len(tasks))
+	}
+}
+
+func TestMCPCreateRefusesASecondLevelOfSubtask(t *testing.T) {
+	ts := newTestServer(t)
+	ts.bootstrap(t)
+
+	parent := ts.callTool(t, "create_task", map[string]any{"content": "Runen v2"})
+	child := ts.callTool(t, "create_task", map[string]any{
+		"content": "Tegn ikonet", "parent_id": parent["id"],
+	})
+
+	// A tool that refuses reports it inside the result with isError, not as a
+	// JSON-RPC error — the call itself was well formed, the arguments were not.
+	response := ts.rpc(t, "tools/call", map[string]any{
+		"name":      "create_task",
+		"arguments": map[string]any{"content": "Endnu dybere", "parent_id": child["id"]},
+	})
+	result, _ := response["result"].(map[string]any)
+	if result == nil || result["isError"] != true {
+		t.Errorf("a sub-task of a sub-task was accepted: %v", response)
+	}
+}

internal/httpapi/mcp_handlers.go

@@ -4,6 +4,7 @@ import (
 	"context"
 	"encoding/json"
 	"errors"
+	"fmt"
 	"io"
 	"net/http"
 	"strings"
@@ -57,7 +58,8 @@ func (s *Server) buildMCP() *mcp.Server {
 		InputSchema: mcp.Schema(map[string]any{
 			"text":        mcp.Str("The task as a sentence, parsed for date, time, priority, #project, @label and recurrence."),
 			"content":     mcp.Str("The task title, if not using `text`."),
-			"project_id":  mcp.Str("Which project. Defaults to the Inbox."),
+			"project_id":  mcp.Str("Which project. Defaults to the Inbox. Naming a project that does not exist is not an error — the task goes to the Inbox and the answer says so."),
+			"parent_id":   mcp.Str("Make this a sub-task of that task. It joins the parent's project. One level deep."),
 			"due_date":    mcp.Str("A date as YYYY-MM-DD."),
 			"priority":    mcp.Int("1 (highest) to 4 (none)."),
 			"description": mcp.Str("Longer notes on the task."),
@@ -253,6 +255,7 @@ func (s *Server) mcpCreateTask(ctx context.Context, userID string, args json.Raw
 		Text        string   `json:"text"`
 		Content     string   `json:"content"`
 		ProjectID   string   `json:"project_id"`
+		ParentID    string   `json:"parent_id"`
 		DueDate     string   `json:"due_date"`
 		Priority    int      `json:"priority"`
 		Description string   `json:"description"`
@@ -268,6 +271,11 @@ func (s *Server) mcpCreateTask(ctx context.Context, userID string, args json.Raw
 	task := &store.Task{CreatedBy: userID, Priority: 4}
 	labels := params.Labels
 
+	// Reported below rather than swallowed. "#Dekoration" used to vanish from the
+	// title while the task went to the Inbox, with nothing anywhere saying so —
+	// invisible in a chat, where nobody sees the row that was written.
+	unknownProject := ""
+
 	if text := strings.TrimSpace(params.Text); text != "" {
 		parsed := quickadd.Parse(text, time.Now().In(userLocation(user.Timezone)), user.Locale)
 		task.Content = parsed.Content
@@ -280,6 +288,8 @@ func (s *Server) mcpCreateTask(ctx context.Context, userID string, args json.Raw
 		if parsed.Project != "" && params.ProjectID == "" {
 			if id, err := s.db.ProjectByName(ctx, userID, parsed.Project); err == nil {
 				task.ProjectID = id
+			} else {
+				unknownProject = parsed.Project
 			}
 		}
 	}
@@ -305,6 +315,23 @@ func (s *Server) mcpCreateTask(ctx context.Context, userID string, args json.Raw
 	if params.ProjectID != "" {
 		task.ProjectID = params.ProjectID
 	}
+
+	// A sub-task belongs to its parent's project, whatever else was asked for:
+	// the two cannot disagree, and the parent is the more specific instruction.
+	// Without this the tools could not build a tree at all — an import of a
+	// parent with seven children arrived as eight unrelated tasks.
+	if params.ParentID != "" {
+		parent, err := s.db.GetTask(ctx, params.ParentID, userID)
+		if err != nil {
+			return nil, mcp.ArgError("no task with id %q to hang this under", params.ParentID)
+		}
+		if parent.ParentID != "" {
+			return nil, mcp.ArgError("sub-tasks are one level deep; %q is already a sub-task", params.ParentID)
+		}
+		task.ParentID = parent.ID
+		task.ProjectID = parent.ProjectID
+	}
+
 	if task.ProjectID == "" {
 		if task.ProjectID, err = s.db.InboxID(ctx, userID); err != nil {
 			return nil, err
@@ -319,10 +346,23 @@ func (s *Server) mcpCreateTask(ctx context.Context, userID string, args json.Raw
 	}
 
 	s.hub.Publish(task.ProjectID, "task.created", toTaskJSON(*task))
-	return map[string]any{
+
+	out := map[string]any{
 		"id": task.ID, "content": task.Content, "priority": task.Priority,
 		"due_date": task.DueDate, "project_id": task.ProjectID,
-	}, nil
+	}
+	if task.ParentID != "" {
+		out["parent_id"] = task.ParentID
+	}
+	if unknownProject != "" {
+		// Phrased for a model to relay: it says what happened and what to do,
+		// so the person is told rather than left with a task in the wrong place.
+		out["note"] = fmt.Sprintf(
+			"There is no project called %q, so this went to the Inbox. "+
+				"Create the project and move it, or say which project you meant.",
+			unknownProject)
+	}
+	return out, nil
 }
 
 func (s *Server) mcpUpdateTask(ctx context.Context, userID string, args json.RawMessage) (any, error) {
@@ -364,8 +404,11 @@ func (s *Server) mcpUpdateTask(ctx context.Context, userID string, args json.Raw
 	if params.Labels != nil {
 		update.SetLabels, update.Labels = true, *params.Labels
 	}
+	// Moved before the field update, and through the same helper the REST handler
+	// uses. This used to check the caller's rights on the destination and then
+	// drop the argument, so the task never moved and the answer still said OK.
 	if params.ProjectID != nil {
-		if _, err := store.RequireProjectRole(ctx, s.db, *params.ProjectID, userID, store.RoleEditor); err != nil {
+		if err := s.moveTaskToProject(ctx, params.TaskID, *params.ProjectID, userID); err != nil {
 			return nil, mcp.ArgError("no project with id %q that you can write to", *params.ProjectID)
 		}
 	}
@@ -379,9 +422,13 @@ func (s *Server) mcpUpdateTask(ctx context.Context, userID string, args json.Raw
 	}
 	s.hub.Publish(task.ProjectID, "task.updated", toTaskJSON(*task))
 
+	// project_id is in the answer because it is one of the things that can be
+	// changed here: a caller that asked for a move can see whether it happened
+	// rather than taking "OK" on trust.
 	return map[string]any{
 		"id": task.ID, "content": task.Content, "priority": task.Priority,
 		"due_date": task.DueDate, "labels": task.Labels,
+		"project_id": task.ProjectID,
 	}, nil
 }
 

internal/httpapi/tasks_handlers.go

@@ -1,6 +1,8 @@
 package httpapi
 
 import (
+	"context"
+	"errors"
 	"net/http"
 	"strconv"
 	"strings"
@@ -249,6 +251,16 @@ func (s *Server) handleUpdateTask(w http.ResponseWriter, r *http.Request) {
 		return
 	}
 
+	// A change of project is a move, not a field: it has to renumber the task
+	// among its new neighbours. Done before the rest so a request that both moves
+	// and edits ends up entirely applied or entirely refused.
+	if req.ProjectID != nil {
+		if err := s.moveTaskToProject(r.Context(), taskID, *req.ProjectID, user.ID); err != nil {
+			writeError(w, http.StatusNotFound, CodeNotFound, err.Error())
+			return
+		}
+	}
+
 	u := store.TaskUpdate{
 		Description: req.Description, Priority: req.Priority,
 		SectionID: req.SectionID, ParentID: req.ParentID,
@@ -473,11 +485,18 @@ func (s *Server) handleQuickAdd(w http.ResponseWriter, r *http.Request) {
 	}
 
 	projectID := req.ProjectID
+	// Set when the text named a project that does not exist. The task is still
+	// created — see below — but the caller is told, because the alternative is
+	// what it used to be: "#Dekoration" disappears from the title, the task lands
+	// somewhere else, and nothing anywhere says why.
+	unknownProject := ""
 	if parsed.Project != "" {
 		// An unknown "#name" is not an error: the task still gets created, in the
 		// Inbox, rather than a thought being thrown away over a typo.
 		if id, err := s.db.ProjectByName(r.Context(), user.ID, parsed.Project); err == nil {
 			projectID = id
+		} else {
+			unknownProject = parsed.Project
 		}
 	}
 	if projectID == "" {
@@ -510,6 +529,16 @@ func (s *Server) handleQuickAdd(w http.ResponseWriter, r *http.Request) {
 	t.Labels = parsed.Labels
 	s.activity(r, t.ProjectID, t.ID, "task.created", map[string]any{"content": t.Content})
 	s.publish(t.ProjectID, "task.created", toTaskJSON(*t))
+
+	if unknownProject != "" {
+		// Alongside the task rather than instead of it: the task was created, and
+		// this says what could not be honoured while creating it.
+		writeJSON(w, http.StatusCreated, struct {
+			taskJSON
+			UnknownProject string `json:"unknown_project"`
+		}{toTaskJSON(*t), unknownProject})
+		return
+	}
 	writeJSON(w, http.StatusCreated, toTaskJSON(*t))
 }
 
@@ -525,6 +554,42 @@ func (s *Server) handleQuickAddPreview(w http.ResponseWriter, r *http.Request) {
 
 // --- helpers --------------------------------------------------------------------
 
+// moveTaskToProject moves a task to another project, if that is really what was
+// asked for.
+//
+// Shared by the REST handler and the MCP tool, because they had drifted: both
+// accepted project_id on an update, both checked the caller's rights on the
+// destination — which reads as "understood" — and then neither passed it on,
+// because store.TaskUpdate has no such field. The task stayed where it was and
+// the response said OK. An argument that is validated and then dropped is worse
+// than one that is refused.
+//
+// A move rather than a field assignment: sort_order is per project, so landing
+// in a new one means being given a position among its tasks.
+func (s *Server) moveTaskToProject(ctx context.Context, taskID, projectID, userID string) error {
+	if projectID == "" {
+		return nil
+	}
+	current, err := s.db.GetTask(ctx, taskID, userID)
+	if err != nil {
+		return errors.New("not found")
+	}
+	if current.ProjectID == projectID {
+		return nil // already there; not worth a write or a renumber
+	}
+	if _, err := store.RequireProjectRole(ctx, s.db, projectID, userID, store.RoleEditor); err != nil {
+		return errors.New("not found")
+	}
+
+	// No neighbours: it lands at the start of the destination, which is the only
+	// answer available when the caller did not say where. Section is cleared —
+	// a section belongs to the project being left behind.
+	if _, err := s.db.MoveTask(ctx, taskID, projectID, "", "", ""); err != nil {
+		return errors.New("not found")
+	}
+	return nil
+}
+
 func validateTaskContent(content string, priority *int) map[string]string {
 	fields := map[string]string{}
 	switch {