Move test database to _/tmp (cabdir)

- Document _/ directory structure in AGENTS.md - Change test database
path from .tasks/ to _/tmp/ - Update all references in tests and docs

5 files changed, 17 insertions, 9 deletions

diff --git a/AGENTS.md b/AGENTS.md
index 2656144..3c42c8c 100644
--- a/AGENTS.md
+++ b/AGENTS.md
@@ -38,6 +38,13 @@ task update <id> done --json
 task create "Command X fails when Y" --discovered-from=<current-task-id> --json
 ```
 
+## Directory Structure
+
+- **`_/`** (cabdir) - All ephemeral/generated files. This directory is gitignored.
+  - `_/llm/` - AI planning docs and agent logs
+  - `_/tmp/` - Temporary files, test databases, scratch data
+- Never create dotfile directories (like `.tasks/`) in the repo root
+
 ## Documentation
 
 - **Project Context**: [README.md](README.md) - Goals, source layout, and coding conventions.
diff --git a/Omni/Task.hs b/Omni/Task.hs
index 9cb061c..83b8e0d 100644
--- a/Omni/Task.hs
+++ b/Omni/Task.hs
@@ -19,7 +19,7 @@ import Omni.Task.Core
 import qualified Omni.Task.RaceTest as RaceTest
 import qualified Omni.Test as Test
 import qualified System.Console.Docopt as Docopt
-import System.Directory (doesFileExist, removeFile)
+import System.Directory (createDirectoryIfMissing, doesFileExist, removeFile)
 import System.Environment (setEnv)
 import qualified Test.Tasty as Tasty
 import Prelude (read)
@@ -403,11 +403,12 @@ unitTests =
   Test.group
     "Unit tests"
     [ Test.unit "setup test database" <| do
-        -- Set up test mode for all tests
+        -- Set up test mode for all tests (uses _/tmp/tasks-test.db)
         setEnv "TASK_TEST_MODE" "1"
 
         -- Clean up test database before all tests
-        let testFile = ".tasks/tasks-test.db"
+        let testFile = "_/tmp/tasks-test.db"
+        createDirectoryIfMissing True "_/tmp"
         exists <- doesFileExist testFile
         when exists <| removeFile testFile
         initTaskDb
diff --git a/Omni/Task/Core.hs b/Omni/Task/Core.hs
index 3b4eaa0..bf52c2c 100644
--- a/Omni/Task/Core.hs
+++ b/Omni/Task/Core.hs
@@ -238,9 +238,9 @@ getTasksDbPath = do
   customPath <- lookupEnv "TASK_DB_PATH"
   testMode <- lookupEnv "TASK_TEST_MODE"
   let path = case (testMode, customPath) of
-        (Just "1", _) -> ".tasks/tasks-test.db" -- Test mode always uses test db
+        (Just "1", _) -> "_/tmp/tasks-test.db" -- Test mode uses cabdir
         (_, Just p) -> p -- Custom path for production
-        _ -> ".tasks/tasks.db"
+        _ -> "_/tmp/tasks.db" -- Default uses cabdir
   pure path
 
 -- DB Helper
@@ -254,7 +254,7 @@ withDb action = do
 -- Initialize the task database
 initTaskDb :: IO ()
 initTaskDb = do
-  createDirectoryIfMissing True ".tasks"
+  createDirectoryIfMissing True "_/tmp"
   withDb <| \conn -> do
     SQL.execute_
       conn
diff --git a/Omni/Task/README.md b/Omni/Task/README.md
index 5113002..463c9e5 100644
--- a/Omni/Task/README.md
+++ b/Omni/Task/README.md
@@ -333,7 +333,7 @@ To back up or transfer tasks, use `task export` and `task import`.
 # Set test mode to protect production database
 export TASK_TEST_MODE=1
 
-# Now all task operations use .tasks/tasks-test.db
+# Now all task operations use _/tmp/tasks-test.db
 task create "Test task" --type=task
 task list
 task tree
diff --git a/Omni/Task/RaceTest.hs b/Omni/Task/RaceTest.hs
index 5dd7fa1..007046f 100644
--- a/Omni/Task/RaceTest.hs
+++ b/Omni/Task/RaceTest.hs
@@ -18,11 +18,11 @@ test = Test.group "Omni.Task.Race" [raceTest]
 raceTest :: Test.Tree
 raceTest =
   Test.unit "concurrent child creation (race condition)" <| do
-    -- Set up test mode (uses .tasks/tasks-test.db)
+    -- Set up test mode (uses _/tmp/tasks-test.db)
     setEnv "TASK_TEST_MODE" "1"
 
     -- Clean up test database
-    let testFile = ".tasks/tasks-test.db"
+    let testFile = "_/tmp/tasks-test.db"
     exists <- doesFileExist testFile
     when exists <| removeFile testFile
     initTaskDb