1 files changed, 117 insertions, 0 deletions
diff --git a/Omni/Agent/DESIGN.md b/Omni/Agent/DESIGN.md
new file mode 100644
index 0000000..ae1f6b3
--- /dev/null
+++ b/Omni/Agent/DESIGN.md
@@ -0,0 +1,117 @@
+# Multi-Agent System 2.0 Design
+
+**Goal:** Replace the current bash-script based worker system (`start-worker.sh`, etc.) with a robust, type-safe Haskell application `Omni/Agent.hs`.
+
+## 1. CLI Interface
+
+The `agent` command (compiled from `Omni/Agent.hs`) will provide a unified interface for managing workers.
+
+```bash
+agent start <name> [--background]  # Start a worker (foreground by default, background with flag)
+agent stop <name>                  # Stop a background worker
+agent status                       # List all workers and their status
+agent log <name> [-f]              # View/tail worker logs
+agent sync                         # Sync local state with live (helper)
+```
+
+## 2. Module Structure (`Omni/Agent/`)
+
+We will refactor the bash logic into Haskell modules:
+
+- **Omni.Agent** (`Omni/Agent.hs`): Main entry point and CLI parsing (Docopt).
+- **Omni.Agent.Core**: Core data types and state management.
+- **Omni.Agent.Worker**: The worker loop logic (sync, claim, work, submit).
+- **Omni.Agent.Git**: Git operations (worktree, branch, merge, commit).
+- **Omni.Agent.Process**: Process management (PID files, signals).
+- **Omni.Agent.Log**: Log streaming and filtering (the "monitor" logic).
+
+## 3. Data Types
+
+```haskell
+data WorkerStatus
+  = Idle
+  | Syncing
+  | Working TaskId
+  | Submitting TaskId
+  | Error Text
+  deriving (Show, Eq, Generic)
+
+data Worker = Worker
+  { workerName :: Text
+  , workerPid :: Maybe Int
+  , workerStatus :: WorkerStatus
+  , workerPath :: FilePath
+  }
+```
+
+## 4. Implementation Details
+
+### 4.1 Worker Loop (`agent start`)
+The Haskell implementation should replicate the logic of `start-worker.sh` but with better error handling and logging.
+
+1.  **Setup**: Ensure worktree exists (or create it).
+2.  **Loop**:
+    - `Git.syncWithLive` (Rebase-based to preserve local history)
+    - `Task.sync`
+    - `task <- Task.findReady`
+    - If `task`:
+        - `Task.claim task`
+        - `baseBranch <- Git.determineBaseBranch task` (Check dependencies)
+        - `Git.checkoutTaskBranch task baseBranch` (Force checkout to clean untracked files)
+        - `Engine.runAgent prompt` (Native LLM agent via OpenRouter)
+        - `Git.commit`
+        - `Git.checkoutBase`
+        - `Task.submitReview task`
+    - Else: `sleep 60`
+
+### 4.2 Process Management
+- Store PIDs in `.tasks/workers/<name>.pid`.
+- `agent stop` sends SIGTERM to the PID.
+- `agent status` checks if PID is alive.
+
+### 4.3 Logging
+- The Engine module uses callbacks to report activity and costs in real-time.
+- `agent log` displays the status bar with worker progress information.
+- **UI Design**:
+    - **Two-line Status**: The CLI should maintain two reserved lines at the bottom (or top) of the output for each worker:
+        - **Line 1 (Meta)**: `[Worker: omni-worker-1] Task: t-123 | Files: 3 | Credits: $0.45 | Time: 05:23`
+        - **Line 2 (Activity)**: `[14:05:22] 🤖 Thinking...` (updates in place)
+    - **Task Details**: When claiming a task, print the full task description/details to the log/console so the user can see what is being worked on without looking it up.
+    - **Completion**: When a task finishes, print a summary line (e.g., `[✓] Task t-123 completed in 12m 30s`) and a hard line break before starting the next loop.
+    - **History**: Previous log lines (tool outputs, thoughts) scroll up above these two status lines.
+
+### 4.5 Git Robustness (Learnings)
+- **Identity**: Configure `git config user.name "Omni Worker"` and `user.email` in the worktree to clearly distinguish worker commits from human commits.
+- **Force Checkout**: The worker must use `git checkout -f` (or equivalent) when switching to task branches to ensure untracked files (like `.tasks/counters.jsonl`) don't block the switch.
+- **Base Branch Logic**: 
+    - If the task depends on another task that is *not* yet in `live` (e.g., in `Review`), the worker should branch off the dependency's branch (`task/<dep-id>`).
+    - Otherwise, branch off `live` directly. Do NOT use the local worker branch (`omni-worker-N`) as the base, as it may contain temporary sync commits that shouldn't be merged.
+- **Commit Hygiene**: Bundle the task status update (marking as 'Review') *inside* the feature implementation commit. This keeps the history clean (one commit per feature) and avoids separate "sync" commits for status changes.
+- **Clean State**: The worker should ensure the workspace is clean (no uncommitted changes) before starting a new loop iteration.
+- **Rebase Safety**: Always check the exit code of `git rebase`. If it fails (conflicts), abort immediately (`git rebase --abort`) to avoid leaving the repo in a broken interactive rebase state.
+- **Status Verification**: Verify that task status updates actually succeed. Check `task ready` output against `live` state to prevent "zombie" tasks (completed in live but stuck in local loop) from being re-claimed.
+- **Binary Freshness**: Ensure the `task` binary used by the worker is rebuilt/updated when source code changes, otherwise logic fixes (like `task ready` filtering) won't take effect.
+
+## 5. Migration Strategy
+
+1.  **Parallel Existence**: Keep bash scripts while developing Haskell version.
+2.  **Feature Parity**: Ensure `agent start` works exactly like `start-worker.sh`.
+3.  **Cutover**: Update `WORKER_AGENT_GUIDE.md` to use `agent` command.
+4.  **Cleanup**: Delete bash scripts.
+
+## 6. Testing Plan
+
+### 6.1 Unit Tests (`Omni/Agent/Test.hs`)
+- Test `Git` module commands (mocked).
+- Test `Log` filtering logic.
+- Test CLI argument parsing.
+
+### 6.2 Integration Tests
+- Create a temporary test repo.
+- Spawn a worker.
+- Mock the Engine LLM calls or use a test API key.
+- Verify task moves from Open -> InProgress -> Review.
+
+## 7. References
+- `Omni/Agent/start-worker.sh` (Current implementation)
+- `Omni/Task.hs` (Task manager integration)