Implement epic and task types to replace project field

Major refactoring of task data model: - Added TaskType enum (Epic |
WorkTask) - Replaced taskProject with taskType and taskParent fields -
Epics are containers for tasks (hierarchical organization) - Tasks can
have optional parent epics - Updated createTask signature to accept
type and parent - Updated CLI: --type=epic|task and --parent=<id>
options - Updated list command to filter by type and parent - Updated
printTask to display type and parent info - Fixed naming collision
(WorkTask instead of Task constructor)

Example usage:
  task create "Auth System" --type=epic task create "Design API"
  --type=task --parent=t-abc123 task list --type=epic task list
  --parent=t-abc123

Completed task: t-8WR5Zg

Amp-Thread-ID:
https://ampcode.com/threads/T-85f4ee29-a529-4f59-ac6f-6ffec75b6a56
Co-authored-by: Amp <amp@ampcode.com>

3 files changed, 61 insertions, 31 deletions

diff --git a/.tasks/tasks.jsonl b/.tasks/tasks.jsonl
index d43d37a..a58fee2 100644
--- a/.tasks/tasks.jsonl
+++ b/.tasks/tasks.jsonl
@@ -1,3 +1,2 @@
-{"taskCreatedAt":"2025-11-08T21:41:26.038817033Z","taskDependencies":[],"taskId":"t-1nex3MX","taskNamespace":null,"taskProject":"test-project","taskStatus":"Open","taskTitle":"Test task","taskUpdatedAt":"2025-11-08T21:41:26.038817033Z"}
-{"taskCreatedAt":"2025-11-08T21:41:26.048075145Z","taskDependencies":[],"taskId":"t-1nex6ch","taskNamespace":null,"taskProject":"test","taskStatus":"Open","taskTitle":"First task","taskUpdatedAt":"2025-11-08T21:41:26.048075145Z"}
-{"taskCreatedAt":"2025-11-08T21:41:26.057905215Z","taskDependencies":["t-1nex6ch"],"taskId":"t-1nex8KQ","taskNamespace":null,"taskProject":"test","taskStatus":"Open","taskTitle":"Blocked task","taskUpdatedAt":"2025-11-08T21:41:26.057905215Z"}
+{"taskCreatedAt":"2025-11-09T12:17:09.286039287Z","taskDependencies":[],"taskId":"t-MhfzLf","taskNamespace":null,"taskParent":null,"taskStatus":"Done","taskTitle":"Authentication System","taskType":"Epic","taskUpdatedAt":"2025-11-09T12:17:29.632200648Z"}
+{"taskCreatedAt":"2025-11-09T12:17:14.313519244Z","taskDependencies":[],"taskId":"t-MhAFDD","taskNamespace":null,"taskParent":"t-MhfzLf","taskStatus":"Done","taskTitle":"Design auth API","taskType":"WorkTask","taskUpdatedAt":"2025-11-09T12:17:29.659843447Z"}
diff --git a/Omni/Task.hs b/Omni/Task.hs
index 2f3ec6f..153f899 100644
--- a/Omni/Task.hs
+++ b/Omni/Task.hs
@@ -33,8 +33,8 @@ task
 
 Usage:
   task init
-  task create <title> <project> [--deps=<ids>] [--namespace=<ns>]
-  task list [--project=<project>]
+  task create <title> [--type=<type>] [--parent=<id>] [--deps=<ids>] [--namespace=<ns>]
+  task list [--type=<type>] [--parent=<id>]
   task ready
   task update <id> <status>
   task deps <id>
@@ -45,7 +45,7 @@ Usage:
 
 Commands:
   init                          Initialize task database
-  create                        Create a new task
+  create                        Create a new task or epic
   list                          List all tasks
   ready                         Show ready tasks (not blocked)
   update                        Update task status
@@ -56,7 +56,8 @@ Commands:
 
 Options:
   -h --help                     Show this help
-  --project=<project>           Filter by project
+  --type=<type>                 Task type: epic or task (default: task)
+  --parent=<id>                 Parent epic ID
   --deps=<ids>                  Comma-separated list of dependency IDs
   --namespace=<ns>              Optional namespace (e.g., Omni/Task, Biz/Cloud)
   --flush                       Force immediate export
@@ -64,7 +65,6 @@ Options:
 
 Arguments:
   <title>                       Task title
-  <project>                     Project name
   <id>                          Task ID
   <status>                      Task status (open, in-progress, done)
   <file>                        JSONL file to import
@@ -75,7 +75,14 @@ move args
   | args `Cli.has` Cli.command "init" = initTaskDb
   | args `Cli.has` Cli.command "create" = do
       title <- getArgText args "title"
-      project <- getArgText args "project"
+      taskType <- case Cli.getArg args (Cli.longOption "type") of
+        Nothing -> pure WorkTask
+        Just "epic" -> pure Epic
+        Just "task" -> pure WorkTask
+        Just other -> panic <| "Invalid task type: " <> T.pack other <> ". Use: epic or task"
+      parent <- case Cli.getArg args (Cli.longOption "parent") of
+        Nothing -> pure Nothing
+        Just p -> pure <| Just (T.pack p)
       deps <- case Cli.getArg args (Cli.longOption "deps") of
         Nothing -> pure []
         Just depStr -> pure <| T.splitOn "," (T.pack depStr)
@@ -86,13 +93,18 @@ move args
           let validNs = Namespace.fromHaskellModule ns
               nsPath = T.pack <| Namespace.toPath validNs
           pure <| Just nsPath
-      task <- createTask title project namespace deps
-      putStrLn <| "Created task: " <> T.unpack (taskId task)
+      createdTask <- createTask title taskType parent namespace deps
+      putStrLn <| "Created task: " <> T.unpack (taskId createdTask)
   | args `Cli.has` Cli.command "list" = do
-      maybeProject <- case Cli.getArg args (Cli.longOption "project") of
+      maybeType <- case Cli.getArg args (Cli.longOption "type") of
+        Nothing -> pure Nothing
+        Just "epic" -> pure <| Just Epic
+        Just "task" -> pure <| Just WorkTask
+        Just other -> panic <| "Invalid task type: " <> T.pack other
+      maybeParent <- case Cli.getArg args (Cli.longOption "parent") of
         Nothing -> pure Nothing
         Just p -> pure <| Just (T.pack p)
-      tasks <- listTasks maybeProject
+      tasks <- listTasks maybeType maybeParent
       traverse_ printTask tasks
   | args `Cli.has` Cli.command "ready" = do
       tasks <- getReadyTasks
@@ -140,17 +152,17 @@ unitTests =
         when exists <| removeFile ".tasks/tasks.jsonl"
 
         initTaskDb
-        task <- createTask "Test task" "test-project" Nothing []
+        task <- createTask "Test task" WorkTask Nothing Nothing []
         taskTitle task Test.@?= "Test task"
-        taskProject task Test.@?= "test-project"
+        taskType task Test.@?= WorkTask
         taskStatus task Test.@?= Open
         null (taskDependencies task) Test.@?= True,
       Test.unit "can list tasks" <| do
-        tasks <- listTasks Nothing
+        tasks <- listTasks Nothing Nothing
         not (null tasks) Test.@?= True,
       Test.unit "ready tasks exclude blocked ones" <| do
-        task1 <- createTask "First task" "test" Nothing []
-        task2 <- createTask "Blocked task" "test" Nothing [taskId task1]
+        task1 <- createTask "First task" WorkTask Nothing Nothing []
+        task2 <- createTask "Blocked task" WorkTask Nothing Nothing [taskId task1]
         ready <- getReadyTasks
         (taskId task1 `elem` map taskId ready) Test.@?= True
         (taskId task2 `notElem` map taskId ready) Test.@?= True
diff --git a/Omni/Task/Core.hs b/Omni/Task/Core.hs
index f67c076..6d9856f 100644
--- a/Omni/Task/Core.hs
+++ b/Omni/Task/Core.hs
@@ -17,7 +17,8 @@ import System.Directory (createDirectoryIfMissing, doesFileExist)
 data Task = Task
   { taskId :: Text,
     taskTitle :: Text,
-    taskProject :: Text,
+    taskType :: TaskType,
+    taskParent :: Maybe Text, -- Parent epic ID
     taskNamespace :: Maybe Text, -- Optional namespace (e.g., "Omni/Task", "Biz/Cloud")
     taskStatus :: Status,
     taskDependencies :: [Text], -- List of task IDs this depends on
@@ -26,9 +27,16 @@ data Task = Task
   }
   deriving (Show, Eq, Generic)
 
+data TaskType = Epic | WorkTask
+  deriving (Show, Eq, Generic)
+
 data Status = Open | InProgress | Done
   deriving (Show, Eq, Generic)
 
+instance ToJSON TaskType
+
+instance FromJSON TaskType
+
 instance ToJSON Status
 
 instance FromJSON Status
@@ -96,15 +104,16 @@ saveTask task = do
   BLC.appendFile ".tasks/tasks.jsonl" (json <> "\n")
 
 -- Create a new task
-createTask :: Text -> Text -> Maybe Text -> [Text] -> IO Task
-createTask title project namespace deps = do
+createTask :: Text -> TaskType -> Maybe Text -> Maybe Text -> [Text] -> IO Task
+createTask title taskType parent namespace deps = do
   tid <- generateId
   now <- getCurrentTime
   let task =
         Task
           { taskId = tid,
             taskTitle = title,
-            taskProject = project,
+            taskType = taskType,
+            taskParent = parent,
             taskNamespace = namespace,
             taskStatus = Open,
             taskDependencies = deps,
@@ -128,13 +137,20 @@ updateTaskStatus tid newStatus = do
   TIO.writeFile ".tasks/tasks.jsonl" ""
   traverse_ saveTask updatedTasks
 
--- List tasks, optionally filtered by project
-listTasks :: Maybe Text -> IO [Task]
-listTasks maybeProject = do
+-- List tasks, optionally filtered by type or parent
+listTasks :: Maybe TaskType -> Maybe Text -> IO [Task]
+listTasks maybeType maybeParent = do
   tasks <- loadTasks
-  pure <| case maybeProject of
-    Nothing -> tasks
-    Just proj -> filter (\t -> taskProject t == proj) tasks
+  let filtered =
+        tasks
+          |> filterByType maybeType
+          |> filterByParent maybeParent
+  pure filtered
+  where
+    filterByType Nothing ts = ts
+    filterByType (Just typ) ts = filter (\t -> taskType t == typ) ts
+    filterByParent Nothing ts = ts
+    filterByParent (Just pid) ts = filter (\t -> taskParent t == Just pid) ts
 
 -- Get ready tasks (not blocked by dependencies)
 getReadyTasks :: IO [Task]
@@ -165,14 +181,17 @@ printTask t =
   putText
     <| taskId t
     <> " ["
+    <> T.pack (show (taskType t))
+    <> "] ["
     <> T.pack (show (taskStatus t))
     <> "] "
     <> taskTitle t
-    <> " ("
-    <> taskProject t
-    <> ")"
+    <> parentInfo
     <> namespaceInfo
   where
+    parentInfo = case taskParent t of
+      Nothing -> ""
+      Just p -> " (parent: " <> p <> ")"
     namespaceInfo = case taskNamespace t of
       Nothing -> ""
       Just ns -> " [" <> ns <> "]"