fix(mcp): allow update wrappers to clear booleans and numerics

copyByJSONTag previously skipped any IsZero value, which made it
impossible for tasks_update / projects_update to flip done from true
to false, reset priority/percent_done to 0, or unarchive a project.

A non-nil pointer src is now the unambiguous "caller supplied this"
signal: dereferenced values are written through even when zero, while
value-typed src fields keep the partial-update semantics. The
affected wrapper fields (Done, IsArchived, IsFavorite, Priority,
PercentDone, RepeatAfter, RepeatMode, BucketID,
CoverImageAttachmentID, ParentProjectID, Position) move to pointer
types so the JSON Schema still marks them optional.

pkg/modules/mcp/inputs.go

@@ -155,14 +155,14 @@ func setInt64Field(dst any, fieldName string, v int64) error {
 //   - Field matching is by the first segment of the `json` tag (i.e.
 //     "title,omitempty" matches "title"). Fields without a json tag (or
 //     tagged `json:"-"`) are skipped on both sides.
-//   - Zero-valued src fields are skipped, so partial updates work
+//   - For value-typed src fields, zero values are skipped so partial
-//     naturally — only fields the caller actually supplied get propagated.
+//     updates work naturally — only fields the caller actually supplied
-//     This mirrors the REST update handler's "omitted JSON keys leave the
+//     get propagated. This mirrors the REST update handler's "omitted
-//     row untouched" behaviour. Wrappers that need to clear a field must
+//     JSON keys leave the row untouched" behaviour.
-//     model it as a pointer (`*string`, `*int`, etc.) so the zero value
+//   - For pointer-typed src fields, a nil pointer is treated as "absent"
-//     is distinguishable from "absent".
+//     and skipped. A non-nil pointer is dereferenced and assigned even
-//   - Pointer src fields are dereferenced. A nil pointer is treated as
+//     when its pointee is the zero value, so wrappers can explicitly set
-//     "absent" and skipped.
+//     `false` / `0` / `""` by modelling the field as a pointer.
 //   - Type compatibility: the helper assigns src's value to dst's field
 //     when the types are directly assignable. time.Time / *time.Time work
 //     out of the box because time.Time is a struct, not a basic type.
@@ -214,17 +214,19 @@ func copyByJSONTag(src, dst any) error {
 			continue
 		}
 		srcVal := sv.Field(i)
-		// Skip nil pointers (caller didn't supply the field) and
+		// A non-nil pointer source is treated as "caller explicitly set
-		// dereference non-nil ones.
+		// this" — even a zero pointee gets propagated so wrappers can
+		// clear booleans / numerics. Value-typed sources fall back to
+		// the IsZero heuristic for partial-update semantics.
+		fromPointer := false
 		if srcVal.Kind() == reflect.Pointer {
 			if srcVal.IsNil() {
 				continue
 			}
 			srcVal = srcVal.Elem()
+			fromPointer = true
 		}
-		if srcVal.IsZero() {
+		if !fromPointer && srcVal.IsZero() {
-			// Zero src value → caller didn't populate this field,
-			// leave dst alone.
 			continue
 		}
 		dstVal := dv.Field(dstIdx)
@@ -343,14 +345,14 @@ type ProjectUpdateInput struct {
 	Identifier string `json:"identifier,omitempty" jsonschema:"new short identifier (max 10 chars); omit to leave unchanged"`
 	// New hex color (without leading #). Omit to leave unchanged.
 	HexColor string `json:"hex_color,omitempty" jsonschema:"new hex color (without leading #); omit to leave unchanged"`
-	// New parent project id. Omit (or zero) to leave unchanged.
+	// New parent project id. Omit to leave unchanged; pass 0 to move to root.
-	ParentProjectID int64 `json:"parent_project_id,omitempty" jsonschema:"new parent project id; omit or 0 to leave unchanged"`
+	ParentProjectID *int64 `json:"parent_project_id,omitempty" jsonschema:"new parent project id; 0 moves to root, omit to leave unchanged"`
-	// New ordering position. Omit (or zero) to leave unchanged.
+	// New ordering position. Omit to leave unchanged; pass 0 to reset.
-	Position float64 `json:"position,omitempty" jsonschema:"new ordering position among siblings; omit or 0 to leave unchanged"`
+	Position *float64 `json:"position,omitempty" jsonschema:"new ordering position among siblings; 0 resets to the start, omit to leave unchanged"`
-	// Archive state. Omit (or false) to leave un-archived.
+	// Archive state. Omit to leave unchanged.
-	IsArchived bool `json:"is_archived,omitempty" jsonschema:"set to true to archive, omit or false to leave un-archived"`
+	IsArchived *bool `json:"is_archived,omitempty" jsonschema:"true to archive, false to un-archive, omit to leave unchanged"`
-	// Favorite state for the caller. Omit (or false) to leave un-favorited.
+	// Favorite state for the caller. Omit to leave unchanged.
-	IsFavorite bool `json:"is_favorite,omitempty" jsonschema:"set to true to favorite for the caller, omit or false to un-favorite"`
+	IsFavorite *bool `json:"is_favorite,omitempty" jsonschema:"true to favorite for the caller, false to un-favorite, omit to leave unchanged"`
 }
 
 // ApplyTo copies the wrapper fields onto a fresh *models.Project. ID is
@@ -427,6 +429,11 @@ func (in *TaskCreateInput) ApplyTo(dst handler.CObject) error {
 // due_date, repeat_after, priority, start_date, end_date, hex_color,
 // percent_done, project_id, bucket_id, repeat_mode, cover_image_attachment_id)
 // are exposed.
+//
+// Booleans and numerics whose zero value carries real meaning ("not done",
+// "no priority", "0% complete", "no bucket") are modelled as pointers so
+// callers can explicitly clear them. A nil pointer means "omit"; a non-nil
+// pointer to the zero value means "set to zero".
 type TaskUpdateInput struct {
 	// ID of the task to update. Required.
 	ID int64 `json:"id" jsonschema:"id of the task to update"`
@@ -436,28 +443,28 @@ type TaskUpdateInput struct {
 	ProjectID int64 `json:"project_id,omitempty" jsonschema:"move the task to a different project; omit to leave unchanged"`
 	// New description.
 	Description string `json:"description,omitempty" jsonschema:"new description; omit to leave unchanged"`
-	// Mark the task as done (true) or undone (false). Defaults to false.
+	// Mark the task as done (true) or undone (false). Omit to leave unchanged.
-	Done bool `json:"done,omitempty" jsonschema:"true marks the task as done"`
+	Done *bool `json:"done,omitempty" jsonschema:"true marks the task as done, false marks it as not done; omit to leave unchanged"`
 	// New due date.
 	DueDate time.Time `json:"due_date,omitempty" jsonschema:"new due date as an RFC 3339 timestamp"`
 	// New start date.
 	StartDate time.Time `json:"start_date,omitempty" jsonschema:"new start date as an RFC 3339 timestamp"`
 	// New end date.
 	EndDate time.Time `json:"end_date,omitempty" jsonschema:"new end date as an RFC 3339 timestamp"`
-	// New repeat interval (seconds).
+	// New repeat interval (seconds). Pass 0 to clear.
-	RepeatAfter int64 `json:"repeat_after,omitempty" jsonschema:"new repeat interval in seconds"`
+	RepeatAfter *int64 `json:"repeat_after,omitempty" jsonschema:"new repeat interval in seconds; 0 clears the repeat"`
-	// New repeat mode.
+	// New repeat mode. Pass 0 for the after-interval mode.
-	RepeatMode int `json:"repeat_mode,omitempty" jsonschema:"new repeat mode: 0 = after interval, 1 = monthly, 3 = from current date"`
+	RepeatMode *int `json:"repeat_mode,omitempty" jsonschema:"new repeat mode: 0 = after interval, 1 = monthly, 3 = from current date"`
-	// New priority.
+	// New priority. Pass 0 to clear.
-	Priority int64 `json:"priority,omitempty" jsonschema:"new priority value"`
+	Priority *int64 `json:"priority,omitempty" jsonschema:"new priority value; 0 clears the priority"`
-	// New percent done between 0 and 1.
+	// New percent done between 0 and 1. Pass 0 to reset.
-	PercentDone float64 `json:"percent_done,omitempty" jsonschema:"new completion percentage between 0 and 1"`
+	PercentDone *float64 `json:"percent_done,omitempty" jsonschema:"new completion percentage between 0 and 1; 0 resets progress"`
 	// New hex color.
 	HexColor string `json:"hex_color,omitempty" jsonschema:"new hex color without leading #"`
-	// New bucket id (move within a kanban view).
+	// New bucket id (move within a kanban view). Pass 0 to detach.
-	BucketID int64 `json:"bucket_id,omitempty" jsonschema:"new kanban bucket id"`
+	BucketID *int64 `json:"bucket_id,omitempty" jsonschema:"new kanban bucket id; 0 detaches from any bucket"`
-	// New cover image attachment id.
+	// New cover image attachment id. Pass 0 to clear.
-	CoverImageAttachmentID int64 `json:"cover_image_attachment_id,omitempty" jsonschema:"new cover image attachment id"`
+	CoverImageAttachmentID *int64 `json:"cover_image_attachment_id,omitempty" jsonschema:"new cover image attachment id; 0 clears the cover"`
 }
 
 // ApplyTo copies the wrapper fields onto a fresh *models.Task. ID is always
@@ -471,8 +478,8 @@ func (in *TaskUpdateInput) ApplyTo(dst handler.CObject) error {
 	if err := copyByJSONTag(in, t); err != nil {
 		return err
 	}
-	if in.RepeatMode != 0 {
+	if in.RepeatMode != nil {
-		t.RepeatMode = models.TaskRepeatMode(in.RepeatMode)
+		t.RepeatMode = models.TaskRepeatMode(*in.RepeatMode)
 	}
 	return nil
 }

pkg/modules/mcp/inputs_test.go

@@ -227,6 +227,66 @@ func TestCopyByJSONTagSkipsZeroValuesForOptional(t *testing.T) {
 	assert.InEpsilon(t, 9.9, dst.Position, 0.0001)
 }
 
+// TestCopyByJSONTagPointerSrcAllowsZero verifies that pointer-typed src
+// fields propagate their pointee even when it's the zero value — this is
+// the escape hatch update wrappers use to let callers explicitly set
+// `done: false` / `priority: 0` / `is_archived: false`.
+func TestCopyByJSONTagPointerSrcAllowsZero(t *testing.T) {
+	type ptrSrc struct {
+		Done     *bool    `json:"done"`
+		Priority *int64   `json:"priority"`
+		Position *float64 `json:"position"`
+		HexColor *string  `json:"hex_color"`
+	}
+	type valDst struct {
+		Done     bool    `json:"done"`
+		Priority int64   `json:"priority"`
+		Position float64 `json:"position"`
+		HexColor string  `json:"hex_color"`
+	}
+
+	falseVal := false
+	zeroInt := int64(0)
+	zeroFloat := 0.0
+	empty := ""
+	src := ptrSrc{
+		Done:     &falseVal,
+		Priority: &zeroInt,
+		Position: &zeroFloat,
+		HexColor: &empty,
+	}
+	dst := valDst{
+		Done:     true,
+		Priority: 5,
+		Position: 1.5,
+		HexColor: "ff0000",
+	}
+	require.NoError(t, copyByJSONTag(src, &dst))
+	assert.False(t, dst.Done, "non-nil pointer with false pointee must overwrite true")
+	assert.Equal(t, int64(0), dst.Priority)
+	assert.InDelta(t, 0.0, dst.Position, 0.0001)
+	assert.Empty(t, dst.HexColor)
+}
+
+// TestCopyByJSONTagNilPointerSrcSkips verifies that nil pointer src fields
+// are treated as "absent" — the dst keeps whatever it had.
+func TestCopyByJSONTagNilPointerSrcSkips(t *testing.T) {
+	type ptrSrc struct {
+		Done     *bool  `json:"done"`
+		Priority *int64 `json:"priority"`
+	}
+	type valDst struct {
+		Done     bool  `json:"done"`
+		Priority int64 `json:"priority"`
+	}
+
+	src := ptrSrc{} // both nil
+	dst := valDst{Done: true, Priority: 7}
+	require.NoError(t, copyByJSONTag(src, &dst))
+	assert.True(t, dst.Done, "nil pointer must not overwrite")
+	assert.Equal(t, int64(7), dst.Priority)
+}
+
 type srcWithPointers struct {
 	Title *string    `json:"title"`
 	Due   *time.Time `json:"due"`
@@ -267,3 +327,41 @@ func TestCopyByJSONTagTimeValue(t *testing.T) {
 	require.NoError(t, copyByJSONTag(src, &dst))
 	assert.Equal(t, now, dst.Due)
 }
+
+// TestProjectUpdateInputClearsBooleans verifies that a wrapper carrying
+// `is_archived: false` (via a non-nil *bool) actually clears IsArchived
+// on the destination Project, even when the dst started with IsArchived=true.
+// This guards the regression flagged in PR review: prior to the pointer-source
+// fix, all zero values were silently dropped by copyByJSONTag.
+func TestProjectUpdateInputClearsBooleans(t *testing.T) {
+	falseVal := false
+	in := &ProjectUpdateInput{ID: 1, IsArchived: &falseVal, IsFavorite: &falseVal}
+	p := &models.Project{ID: 1, IsArchived: true, IsFavorite: true}
+	require.NoError(t, in.ApplyTo(p))
+	assert.False(t, p.IsArchived, "IsArchived must clear when explicitly set to false")
+	assert.False(t, p.IsFavorite, "IsFavorite must clear when explicitly set to false")
+}
+
+// TestTaskUpdateInputClearsBoolsAndZeros mirrors the project test for tasks
+// — done can flip to false, priority can drop to 0, percent_done resets.
+func TestTaskUpdateInputClearsBoolsAndZeros(t *testing.T) {
+	falseVal := false
+	zeroPriority := int64(0)
+	zeroPercent := 0.0
+	in := &TaskUpdateInput{
+		ID:          1,
+		Done:        &falseVal,
+		Priority:    &zeroPriority,
+		PercentDone: &zeroPercent,
+	}
+	tk := &models.Task{
+		ID:          1,
+		Done:        true,
+		Priority:    5,
+		PercentDone: 0.75,
+	}
+	require.NoError(t, in.ApplyTo(tk))
+	assert.False(t, tk.Done)
+	assert.Equal(t, int64(0), tk.Priority)
+	assert.InDelta(t, 0.0, tk.PercentDone, 0.0001)
+}

pkg/webtests/mcp_projects_test.go

@@ -290,6 +290,35 @@ func TestMCP_Projects_Update(t *testing.T) {
 	assert.Equal(t, "Updated description", project["description"])
 }
 
+// TestMCP_Projects_UpdateClearsArchived exercises the pointer-source path
+// of copyByJSONTag: an explicit `is_archived: false` must un-archive a
+// project that was previously archived.
+func TestMCP_Projects_UpdateClearsArchived(t *testing.T) {
+	c := newMCPClient(t, mcpFullProjectsToken)
+
+	createResult := c.callTool("projects_create", map[string]any{
+		"title":       "mcp project to un-archive",
+		"is_archived": true,
+	})
+	require.NotContains(t, createResult, "isError")
+	var created map[string]any
+	require.NoError(t, json.Unmarshal([]byte(toolResultText(t, createResult)), &created))
+	pid := int64(created["id"].(float64))
+	require.True(t, created["is_archived"].(bool), "project should have been created archived")
+
+	updateResult := c.callTool("projects_update", map[string]any{
+		"id":          pid,
+		"is_archived": false,
+	})
+	require.NotContains(t, updateResult, "isError", "update errored: %v", updateResult)
+
+	readResult := c.callTool("projects_read_one", map[string]any{"id": pid})
+	require.NotContains(t, readResult, "isError")
+	var project map[string]any
+	require.NoError(t, json.Unmarshal([]byte(toolResultText(t, readResult)), &project))
+	assert.False(t, project["is_archived"].(bool), "is_archived must be false after explicit clear")
+}
+
 func TestMCP_Projects_Delete(t *testing.T) {
 	c := newMCPClient(t, mcpFullProjectsToken)
 

pkg/webtests/mcp_tasks_test.go

@@ -106,6 +106,36 @@ func TestMCP_Tasks_Update(t *testing.T) {
 	assert.Equal(t, "Updated description", task["description"])
 }
 
+// TestMCP_Tasks_UpdateClearsDone exercises the pointer-source path of
+// copyByJSONTag: a `done: false` explicitly supplied through the JSON
+// args must flip a task from done back to undone.
+func TestMCP_Tasks_UpdateClearsDone(t *testing.T) {
+	c := newMCPClient(t, mcpFullProjectsToken)
+
+	createResult := c.callTool("tasks_create", map[string]any{
+		"title":      "mcp task to undo",
+		"project_id": 1,
+		"done":       true,
+	})
+	require.NotContains(t, createResult, "isError")
+	var created map[string]any
+	require.NoError(t, json.Unmarshal([]byte(toolResultText(t, createResult)), &created))
+	tid := int64(created["id"].(float64))
+	require.True(t, created["done"].(bool), "task should have been created in done state")
+
+	updateResult := c.callTool("tasks_update", map[string]any{
+		"id":   tid,
+		"done": false,
+	})
+	require.NotContains(t, updateResult, "isError", "update errored: %v", updateResult)
+
+	readResult := c.callTool("tasks_read_one", map[string]any{"id": tid})
+	require.NotContains(t, readResult, "isError")
+	var task map[string]any
+	require.NoError(t, json.Unmarshal([]byte(toolResultText(t, readResult)), &task))
+	assert.False(t, task["done"].(bool), "done must be false after explicit clear")
+}
+
 func TestMCP_Tasks_Delete(t *testing.T) {
 	c := newMCPClient(t, mcpFullProjectsToken)