Update deprecated endpoints for v1 API

Phase 2 changes:
- Quick add: quick/add → tasks/quick (REST API with JSON)
- Completed tasks: completed/get_all → tasks/completed/by_completion_date
- Add doRestApi() method for JSON REST endpoints
- Update completed endpoint with required since/until date parameters
- Improve error handling to show full API error responses

🤖 Generated with [Claude Code](https://claude.com/claude-code)

Co-Authored-By: Claude Opus 4.5 <noreply@anthropic.com>

Author: kenliu

MIGRATION_PLAN.md

@@ -43,29 +43,48 @@ const Server = "https://api.todoist.com/api/v1/"
 ```
 
 #### 2. Quick Add Endpoint
-**File**: `lib/todoist.go:106`
+**File**: `lib/todoist.go`
 ```go
 // Current
+var r ExecResult
+values := url.Values{"text": {text}}
 return c.doApi(ctx, http.MethodPost, "quick/add", values, &r)
 
 // Target
-return c.doApi(ctx, http.MethodPost, "tasks/quick_add", values, &r)
+var item Item
+body := map[string]interface{}{"text": text}
+return c.doRestApi(ctx, http.MethodPost, "tasks/quick", body, &item)
 ```
 
+**Changes**:
+- Endpoint: `quick/add` → `tasks/quick`
+- Content-Type: `application/x-www-form-urlencoded` → `application/json`
+- Request body: URL-encoded values → JSON body
+- Response: `ExecResult` → `Item` (task object)
+- Added new `doRestApi()` method for JSON REST endpoints
+
 #### 3. Completed Tasks Endpoint
 **File**: `lib/completed.go:15`
 ```go
 // Current
 return c.doApi(ctx, http.MethodPost, "completed/get_all", url.Values{}, &r)
 
-// Target (note: may need to verify exact endpoint and response format)
-return c.doApi(ctx, http.MethodGet, "tasks/completed_by_completion_date", url.Values{}, &r)
+// Target
+now := time.Now()
+since := now.AddDate(0, 0, -30).Format(time.RFC3339)
+until := now.Format(time.RFC3339)
+params := url.Values{
+    "since": {since},
+    "until": {until},
+}
+return c.doApi(ctx, http.MethodGet, "tasks/completed/by_completion_date", params, &r)
 ```
 
-**Note**: The completed tasks endpoint may require additional investigation:
-- v1 uses `GET` method (vs `POST` in v9)
-- Response format may differ
-- May need pagination handling
+**Changes**:
+- HTTP method: `POST` → `GET`
+- Endpoint: `completed/get_all` → `tasks/completed/by_completion_date`
+- Required parameters: `since` and `until` (ISO 8601 UTC format with Z suffix, max 3 month range)
+- Default behavior: Last 30 days of completed tasks
 
 ---
 

lib/completed.go

@@ -4,6 +4,7 @@ import (
 	"context"
 	"net/http"
 	"net/url"
+	"time"
 )
 
 type Completed struct {
@@ -12,5 +13,16 @@ type Completed struct {
 }
 
 func (c *Client) CompletedAll(ctx context.Context, r *Completed) error {
-	return c.doApi(ctx, http.MethodPost, "completed/get_all", url.Values{}, &r)
+	// v1 API requires since/until parameters in UTC with "Z" suffix (max 3 month range)
+	// Default to last 30 days
+	now := time.Now().UTC()
+	since := now.AddDate(0, 0, -30).Format("2006-01-02T15:04:05Z")
+	until := now.Format("2006-01-02T15:04:05Z")
+
+	params := url.Values{
+		"since": {since},
+		"until": {until},
+	}
+
+	return c.doApi(ctx, http.MethodGet, "tasks/completed/by_completion_date", params, &r)
 }

lib/main.go

@@ -4,6 +4,7 @@ import (
 	"encoding/json"
 	"errors"
 	"fmt"
+	"io"
 	"net/http"
 )
 
@@ -21,9 +22,14 @@ func ParseAPIError(prefix string, resp *http.Response) error {
 		Error string `json:"error"`
 	}
 
-	json.NewDecoder(resp.Body).Decode(&e)
+	bodyBytes, _ := io.ReadAll(resp.Body)
+	resp.Body.Close()
+
+	json.Unmarshal(bodyBytes, &e)
 	if e.Error != "" {
 		errMsg = fmt.Sprintf("%s: %s", errMsg, e.Error)
+	} else if len(bodyBytes) > 0 {
+		errMsg = fmt.Sprintf("%s: %s", errMsg, string(bodyBytes))
 	}
 
 	return errors.New(errMsg)

lib/todoist.go

@@ -85,6 +85,54 @@ func (c *Client) doApi(ctx context.Context, method string, uri string, params ur
 	return json.NewDecoder(resp.Body).Decode(&res)
 }
 
+func (c *Client) doRestApi(ctx context.Context, method string, uri string, body interface{}, res interface{}) error {
+	c.Log("doRestApi: called")
+	u, err := url.Parse(Server)
+	if err != nil {
+		return err
+	}
+	u.Path = path.Join(u.Path, uri)
+
+	c.Log("config: %#v", c.config)
+
+	var bodyReader io.Reader
+	if body != nil {
+		jsonData, err := json.Marshal(body)
+		if err != nil {
+			return err
+		}
+		bodyReader = strings.NewReader(string(jsonData))
+	}
+
+	req, err := http.NewRequest(method, u.String(), bodyReader)
+	if err != nil {
+		return err
+	}
+
+	req.Header.Set("Content-Type", "application/json")
+	req.Header.Set("Authorization", "Bearer "+c.config.AccessToken)
+	req = req.WithContext(ctx)
+
+	c.Log("request: %#v", req)
+	c.Log("request.URL: %#v", req.URL)
+
+	resp, err := c.Do(req)
+	if err != nil {
+		return err
+	}
+	defer resp.Body.Close()
+
+	c.Log("response: %#v", resp)
+
+	if resp.StatusCode != http.StatusOK {
+		c.Log(ParseAPIError("bad request", resp).Error())
+		return ParseAPIError("bad request", resp)
+	} else if res == nil {
+		return nil
+	}
+	return json.NewDecoder(resp.Body).Decode(&res)
+}
+
 type ExecResult struct {
 	SyncToken     string      `json:"sync_token"`
 	SyncStatus    interface{} `json:"sync_status"`
@@ -97,13 +145,13 @@ func (c *Client) ExecCommands(ctx context.Context, commands Commands) error {
 }
 
 func (c *Client) QuickCommand(ctx context.Context, text string) error {
-	var r ExecResult
+	var item Item
 
-	values := url.Values{
-		"text": {text},
+	body := map[string]interface{}{
+		"text": text,
 	}
 
-	return c.doApi(ctx, http.MethodPost, "quick/add", values, &r)
+	return c.doRestApi(ctx, http.MethodPost, "tasks/quick", body, &item)
 }
 
 func (c *Client) Sync(ctx context.Context) error {