Expand docs: tasks, subtasks, Gitea sync use case, Gantt/PM workflows

- Add architecture diagrams showing developer-to-PM bridge
- Document task lifecycle: create, update, track progress, overdue detection
- Add Gitea → OnlyOffice sync example with URL-based matching
- Describe Gantt chart, milestone planning, and executive reporting use cases
- Add sync architecture diagram (cron/webhook/CLI triggers)
- Document all task fields relevant for project planning (dates, priority, milestone)

README.md

@@ -1,15 +1,101 @@
 # go-onlyoffice
 
-Go client library for the [OnlyOffice](https://www.onlyoffice.com/) Project Management API.
+Go client library for the [OnlyOffice](https://www.onlyoffice.com/) Project Management API — manage projects, tasks, subtasks, milestones, and users programmatically.
 
-## Features
+Pairs with [go-gitea-helpers](https://github.com/eSlider/go-gitea-helpers) to bridge developer issue trackers with CRM-grade project management for Gantt charts, resource planning, and executive reporting.
 
-- Token-based authentication with automatic renewal
+## Architecture
-- Project CRUD operations (create, read, update, delete)
+
-- Task management (create, update, list, filter)
+```mermaid
-- Milestone management
+graph TB
-- User listing
+    subgraph "Developer Tools"
-- Query parameter serialization via struct tags
+        GIT["Gitea / GitHub<br/>Issues, PRs, Milestones"]
+    end
+
+    subgraph "go-onlyoffice"
+        CL["Client"]
+        AUTH["Auth<br/>Token-based"]
+        PRJ["Projects"]
+        TSK["Tasks & Subtasks"]
+        MS["Milestones"]
+        USR["Users"]
+    end
+
+    subgraph "OnlyOffice CRM"
+        GANTT["Gantt Charts"]
+        PLAN["Project Planning"]
+        RPT["Reports & Dashboards"]
+        PM["PM Workflow"]
+    end
+
+    GIT -->|"sync issues"| CL
+    CL --> AUTH
+    AUTH --> PRJ
+    AUTH --> TSK
+    AUTH --> MS
+    AUTH --> USR
+
+    PRJ --> GANTT
+    TSK --> GANTT
+    MS --> PLAN
+    TSK --> RPT
+    PRJ --> PM
+```
+
+## The Problem: Developers vs. Project Managers
+
+```mermaid
+graph LR
+    subgraph "Engineering World"
+        DEV["Developers"]
+        GITEA["Gitea / GitHub<br/>Issues & PRs"]
+        CODE["Code Reviews"]
+    end
+
+    subgraph "Management World"
+        PM["Project Managers"]
+        OO["OnlyOffice CRM<br/>Gantt · Planning · Reports"]
+        EXEC["Executives<br/>Status Reports"]
+    end
+
+    DEV -->|"create issues"| GITEA
+    GITEA -.->|"❌ invisible"| PM
+    PM -->|"manual copy"| OO
+    OO --> EXEC
+
+    style GITEA fill:#f96,stroke:#333
+    style OO fill:#69f,stroke:#333
+```
+
+**Without sync:** Project managers manually copy issue titles, deadlines, and status from Gitea into OnlyOffice. Developers don't update the CRM. Gantt charts rot. Reports lie.
+
+**With sync:** Issues flow automatically from Gitea to OnlyOffice with start dates, deadlines, and status. PMs get live Gantt charts. Developers keep working in Git.
+
+```mermaid
+graph LR
+    subgraph "Engineering World"
+        DEV["Developers"]
+        GITEA["Gitea / GitHub"]
+    end
+
+    subgraph "Sync Bridge"
+        SYNC["go-onlyoffice<br/>+ go-gitea-helpers"]
+    end
+
+    subgraph "Management World"
+        OO["OnlyOffice CRM"]
+        GANTT["Gantt Charts ✓"]
+        RPT["Reports ✓"]
+    end
+
+    DEV -->|"create/close issues"| GITEA
+    GITEA -->|"auto-sync"| SYNC
+    SYNC -->|"create/update tasks"| OO
+    OO --> GANTT
+    OO --> RPT
+
+    style SYNC fill:#4a4,stroke:#333,color:#fff
+```
 
 ## Installation
 
@@ -17,7 +103,143 @@ Go client library for the [OnlyOffice](https://www.onlyoffice.com/) Project Mana
 go get github.com/eslider/go-onlyoffice
 ```
 
-## Usage
+For Gitea sync (optional):
+
+```bash
+go get github.com/eslider/go-gitea-helpers
+```
+
+## Quick Start
+
+### Connect and List Projects
+
+```go
+client := onlyoffice.NewClient(onlyoffice.GetEnvironmentCredentials())
+
+projects, _ := client.GetProjects()
+for _, p := range projects {
+    fmt.Printf("[%d] %s — %d tasks\n", *p.ID, *p.Title, safeInt(p.TaskCountTotal))
+}
+```
+
+### Create a Project with Tasks and Deadlines
+
+```go
+// Create a project
+project, _ := client.CreateProject(onlyoffice.NewProjectRequest{
+    Title:       "Q1 2026 Release",
+    Description: "Backend API v2 + mobile app redesign",
+})
+
+// Create tasks with start/end dates (for Gantt chart)
+client.CreateProjectTask(onlyoffice.NewProjectTaskRequest{
+    ProjectId:   *project.ID,
+    Title:       "Design API schema",
+    Description: "OpenAPI 3.1 spec for all endpoints",
+    StartDate:   onlyoffice.Time(time.Now()),
+    Deadline:    onlyoffice.Time(time.Now().AddDate(0, 0, 14)),
+    Priority:    1, // High
+})
+
+client.CreateProjectTask(onlyoffice.NewProjectTaskRequest{
+    ProjectId:   *project.ID,
+    Title:       "Implement auth service",
+    Description: "JWT + OAuth2 + refresh tokens",
+    StartDate:   onlyoffice.Time(time.Now().AddDate(0, 0, 14)),
+    Deadline:    onlyoffice.Time(time.Now().AddDate(0, 1, 0)),
+})
+```
+
+### List and Filter Tasks
+
+```go
+// Get all tasks for a project
+tasks, _ := client.GetTasks(onlyoffice.NewProjectGetTasksRequest(*project.ID))
+
+for _, t := range tasks {
+    status := "open"
+    if t.Status != nil && *t.Status == onlyoffice.ProjectTaskStatusClosed {
+        status = "closed"
+    }
+    fmt.Printf("  [%s] %s", status, *t.Title)
+    if t.Deadline != nil {
+        fmt.Printf(" (due: %s)", t.Deadline.Format("2006-01-02"))
+    }
+    fmt.Println()
+}
+```
+
+### Update Task Status and Dates
+
+```go
+// Close a task and set actual end date
+client.UpdateProjectTask(onlyoffice.ProjectTaskUpdateRequest{
+    ID:       taskID,
+    Title:    "Design API schema",
+    Status:   onlyoffice.ProjectTaskStatusClosed,
+    Deadline: &onlyoffice.Time(time.Now()),
+})
+```
+
+### Get Milestones and Task Progress
+
+```go
+milestones, _ := client.GetProjectMilestones(project)
+for _, ms := range milestones {
+    active := int64(0)
+    closed := int64(0)
+    if ms.ActiveTaskCount != nil { active = *ms.ActiveTaskCount }
+    if ms.ClosedTaskCount != nil { closed = *ms.ClosedTaskCount }
+    total := active + closed
+
+    fmt.Printf("Milestone: %s — %d/%d tasks done", *ms.Title, closed, total)
+    if ms.Deadline != nil {
+        fmt.Printf(" (deadline: %s)", ms.Deadline.Format("2006-01-02"))
+    }
+    fmt.Println()
+}
+```
+
+---
+
+## Use Case: Gitea → OnlyOffice Sync
+
+The primary use case is **bridging developer workflows with project management**. Developers create issues in Gitea; a sync job automatically mirrors them as OnlyOffice tasks with proper start/end dates, enabling PMs to work with Gantt charts without developers leaving their Git workflow.
+
+### Sync Flow
+
+```mermaid
+sequenceDiagram
+    participant Dev as Developer
+    participant Gitea
+    participant Sync as Sync Job
+    participant OO as OnlyOffice
+
+    Dev->>Gitea: Create issue "Add OAuth2"
+    Note over Gitea: issue.Created = Feb 13<br/>issue.Deadline = Mar 1
+
+    Sync->>Gitea: GET /repos/{org}/*/issues
+    Gitea-->>Sync: issues list (paginated)
+
+    Sync->>OO: GET /api/2.0/project/filter.json
+    OO-->>Sync: projects list
+
+    Sync->>Sync: Match Gitea labels → OO projects
+
+    alt Issue not yet in OnlyOffice
+        Sync->>OO: POST /api/2.0/project/{id}/task.json
+        Note over OO: Task created:<br/>Start: Feb 13, End: Mar 1<br/>Description includes Gitea URL
+    else Issue already synced
+        Sync->>OO: PUT /api/2.0/project/task/{id}.json
+        Note over OO: Title, status, dates updated
+    end
+
+    Dev->>Gitea: Close issue "Add OAuth2"
+    Sync->>OO: PUT status → Closed
+    Note over OO: Gantt chart updates automatically
+```
+
+### Sync Example
 
 ```go
 package main
@@ -25,34 +247,263 @@ package main
 import (
     "fmt"
     "log"
+    "os"
+    "strings"
 
+    gitea "github.com/eslider/go-gitea-helpers"
     onlyoffice "github.com/eslider/go-onlyoffice"
 )
 
 func main() {
-    client := onlyoffice.NewClient(onlyoffice.Credentials{
+    // Connect to both services
-        Url:      "https://your-onlyoffice.example.com",
+    oo := onlyoffice.NewClient(onlyoffice.GetEnvironmentCredentials())
-        User:     "admin@example.com",
+    gc, _ := gitea.NewClient(gitea.GetEnvironmentConfig())
-        Password: "your-password",
+    owner := os.Getenv("GITEA_OWNER")
-    })
 
-    // List projects
+    // Load all Gitea issues and OnlyOffice projects
-    projects, err := client.GetProjects()
+    repos, _ := gc.GetAllReposIssues(owner)
-    if err != nil {
+    projects, _ := oo.GetProjects()
-        log.Fatal(err)
+
+    for repoName, repo := range repos {
+        // Find matching OnlyOffice project by name
+        project := projects.Get(repoName)
+        if project == nil {
+            fmt.Printf("SKIP %s (no matching OO project)\n", repoName)
+            continue
+        }
+
+        // Load existing tasks
+        tasks, _ := oo.GetTasks(onlyoffice.NewProjectGetTasksRequest(*project.ID))
+
+        for _, issue := range repo.Issues {
+            // Check if issue is already synced (URL in description)
+            existing := findSyncedTask(tasks, issue.HTMLURL)
+
+            if existing != nil {
+                // Update existing task
+                status := onlyoffice.ProjectTaskStatusOpen
+                if issue.State == "closed" {
+                    status = onlyoffice.ProjectTaskStatusClosed
+                }
+
+                oo.UpdateProjectTask(onlyoffice.ProjectTaskUpdateRequest{
+                    ID:        *existing.ID,
+                    Title:     issue.Title,
+                    Status:    status,
+                    StartDate: timePtr(onlyoffice.Time(issue.Created)),
+                    Deadline:  deadlineFromIssue(issue),
+                })
+                fmt.Printf("  UPDATED: %s\n", issue.Title)
+            } else {
+                // Create new task
+                status := onlyoffice.ProjectTaskStatusOpen
+                if issue.State == "closed" {
+                    status = onlyoffice.ProjectTaskStatusClosed
+                }
+
+                oo.CreateProjectTask(onlyoffice.NewProjectTaskRequest{
+                    ProjectId:   *project.ID,
+                    Title:       issue.Title,
+                    Description: issue.Body + "\n\nURL:" + issue.HTMLURL,
+                    StartDate:   onlyoffice.Time(issue.Created),
+                    Deadline:    *deadlineFromIssue(issue),
+                    Status:      status,
+                })
+                fmt.Printf("  CREATED: %s\n", issue.Title)
+            }
+        }
     }
-    for _, p := range projects {
+}
-        fmt.Printf("Project: %s (ID: %d)\n", *p.Title, *p.ID)
+
+// findSyncedTask checks task descriptions for the Gitea issue URL.
+func findSyncedTask(tasks []*onlyoffice.Task, issueURL string) *onlyoffice.Task {
+    for _, t := range tasks {
+        if t.Description != nil && strings.Contains(*t.Description, issueURL) {
+            return t
+        }
+    }
+    return nil
+}
+```
+
+### What Project Managers Get
+
+Once synced, OnlyOffice provides without any developer intervention:
+
+| Feature | How It Works |
+|---|---|
+| **Gantt Charts** | Tasks have `StartDate` and `Deadline` from Gitea issue created/due dates |
+| **Status Tracking** | Open/closed status mirrors Gitea issue state in real time |
+| **Milestone Planning** | Gitea milestones map to OnlyOffice milestones with progress % |
+| **Resource Allocation** | Task assignees sync so PMs see who's working on what |
+| **Sprint Reports** | Filter by date range to generate sprint/release reports |
+| **Cross-Repo View** | All repos' issues appear as tasks in a unified project board |
+| **Executive Dashboards** | Project progress, overdue tasks, team workload at a glance |
+
+### Recommended Sync Architecture
+
+```mermaid
+graph TB
+    subgraph "Trigger Options"
+        CRON["Cron Job<br/>every 15 min"]
+        HOOK["Gitea Webhook<br/>on issue events"]
+        CLI["Manual CLI<br/>on-demand"]
+    end
+
+    subgraph "Sync Engine"
+        S["Sync Job"]
+        MAP["Label → Project<br/>Mapping"]
+        MATCH["URL-based Task<br/>Matching"]
+        DATE["Date Translation<br/>Created → Start<br/>Deadline → End<br/>Closed → Actual End"]
+    end
+
+    subgraph "Output"
+        OO["OnlyOffice Tasks"]
+        GANTT["Gantt Timeline"]
+        REP["PM Reports"]
+    end
+
+    CRON --> S
+    HOOK --> S
+    CLI --> S
+
+    S --> MAP
+    S --> MATCH
+    S --> DATE
+
+    MAP --> OO
+    MATCH --> OO
+    DATE --> OO
+    OO --> GANTT
+    OO --> REP
+```
+
+---
+
+## Use Case: Task Lifecycle Management
+
+### Creating Tasks with Full Metadata
+
+```go
+task, _ := client.CreateProjectTask(onlyoffice.NewProjectTaskRequest{
+    ProjectId:   projectID,
+    Title:       "Implement payment gateway",
+    Description: "Integrate Stripe API for subscription billing",
+    StartDate:   onlyoffice.Time(time.Date(2026, 3, 1, 0, 0, 0, 0, time.UTC)),
+    Deadline:    onlyoffice.Time(time.Date(2026, 3, 15, 0, 0, 0, 0, time.UTC)),
+    Priority:    1, // High
+    MilestoneId: milestoneID,
+    Notify:      true,
+})
+```
+
+### Tracking Task Progress
+
+```go
+tasks, _ := client.GetTasks(onlyoffice.NewProjectGetTasksRequest(projectID))
+
+open, closed := 0, 0
+var overdue []*onlyoffice.Task
+
+for _, t := range tasks {
+    if t.Status != nil && *t.Status == onlyoffice.ProjectTaskStatusClosed {
+        closed++
+    } else {
+        open++
+        if t.Deadline != nil && t.Deadline.Before(time.Now()) {
+            overdue = append(overdue, t)
+        }
+    }
+}
+
+fmt.Printf("Progress: %d/%d done (%.0f%%)\n", closed, open+closed,
+    float64(closed)/float64(open+closed)*100)
+
+if len(overdue) > 0 {
+    fmt.Printf("⚠ %d overdue tasks:\n", len(overdue))
+    for _, t := range overdue {
+        fmt.Printf("  - %s (due: %s)\n", *t.Title, t.Deadline.Format("2006-01-02"))
     }
 }
 ```
 
-Or load credentials from environment variables:
+### Subtask Management
+
+Tasks support subtasks for breaking work into smaller pieces:
 
 ```go
-client := onlyoffice.NewClient(onlyoffice.GetEnvironmentCredentials())
+type Task struct {
+    ID           *int          `json:"id"`
+    Title        *string       `json:"title"`
+    StartDate    *time.Time    `json:"startDate"`
+    Deadline     *time.Time    `json:"deadline"`
+    Description  *string       `json:"description"`
+    Priority     *int          `json:"priority"`       // High=1, Normal=0, Low=-1
+    Status       *ProjectTaskStatus `json:"status"`    // Open=1, Closed=2
+    Subtasks     []any         `json:"subtasks"`
+    MilestoneID  *int64        `json:"milestoneId"`
+    Responsibles []*User       `json:"responsibles"`   // Assigned team members
+    // ... timestamps, permissions
+}
 ```
 
+---
+
+## API Reference
+
+### Client
+
+| Function | Description |
+|---|---|
+| `NewClient(credentials)` | Create a new API client |
+| `GetEnvironmentCredentials()` | Load from `ONLYOFFICE_*` env vars |
+| `Auth(credentials)` | Authenticate and get token |
+| `Query(request, result)` | Execute raw API request |
+
+### Projects
+
+| Method | Description |
+|---|---|
+| `GetProjects()` | List all projects |
+| `CreateProject(req)` | Create a new project |
+| `UpdateProject(req)` | Update project details |
+| `DeleteProject(id)` | Delete a project |
+| `GetProjectMilestones(project)` | Get milestones with task counts |
+
+### Tasks
+
+| Method | Description |
+|---|---|
+| `GetTasks(req)` | List tasks with filtering |
+| `CreateProjectTask(req)` | Create task with dates, priority, milestone |
+| `UpdateProjectTask(req)` | Update title, status, dates, priority |
+
+### Task Fields for Gantt
+
+| Field | Type | Purpose |
+|---|---|---|
+| `StartDate` | `*time.Time` | Gantt bar start |
+| `Deadline` | `*time.Time` | Gantt bar end |
+| `Status` | `ProjectTaskStatus` | Open (1) / Closed (2) |
+| `Priority` | `*int` | High (1) / Normal (0) / Low (-1) |
+| `MilestoneID` | `*int64` | Groups tasks under milestones |
+| `Responsibles` | `[]*User` | Assigned team members |
+| `Subtasks` | `[]any` | Sub-items within a task |
+
+### Users
+
+| Method | Description |
+|---|---|
+| `GetUsers()` | List all users with profiles |
+
+### Helper Types
+
+| Type | Description |
+|---|---|
+| `Projects` | `[]*Project` with `.Get(title)` lookup |
+| `Time` | `time.Time` wrapper with OnlyOffice JSON format |
+| `Task.GetGiteaIssueLink()` | Extract Gitea URL from task description |
+
 ## Environment Variables
 
 | Variable | Description |
@@ -61,32 +512,19 @@ client := onlyoffice.NewClient(onlyoffice.GetEnvironmentCredentials())
 | `ONLYOFFICE_USER` | Login email or username |
 | `ONLYOFFICE_PASS` | Password |
 
-## API Reference
+## Examples
 
-### Client
+| Example | Description |
+|---|---|
+| [basic](examples/basic/) | List projects and users |
 
-- `NewClient(credentials)` - Create a new client
+## Related Libraries
-- `GetEnvironmentCredentials()` - Load credentials from env vars
-- `Auth(credentials)` - Authenticate and get token
-- `Query(request, result)` - Execute an API request
 
-### Projects
+| Library | Description |
-
+|---|---|
-- `GetProjects()` - List all projects
+| [go-gitea-helpers](https://github.com/eSlider/go-gitea-helpers) | Gitea pagination helpers for issue/repo fetching |
-- `CreateProject(req)` - Create a new project
+| [go-matrix-bot](https://github.com/eSlider/go-matrix-bot) | Matrix bot with OnlyOffice task creation from chat |
-- `UpdateProject(req)` - Update a project
+| [go-trade](https://github.com/eSlider/go-trade) | Unified trade data model across exchanges |
-- `DeleteProject(id)` - Delete a project
-- `GetProjectMilestones(project)` - Get milestones for a project
-
-### Tasks
-
-- `GetTasks(req)` - List tasks with filtering
-- `CreateProjectTask(req)` - Create a new task
-- `UpdateProjectTask(req)` - Update a task
-
-### Users
-
-- `GetUsers()` - List all users
 
 ## License