569 2026 01 27 17 52 14 Insert Before Stream Fix F3d11f8a

---
title: "Insert Before Stream Fix – Execution Log"
phase: Execute
date: "2026-01-27T17:52:14"
owner: "Claude"
plan_path: "memory-bank/plan/reserch.md"
start_commit: "5efc5423"
branch: "fix/insert-before-stream-race"
env: {target: "local", notes: "Creating minimal ChatContainer widget"}
---

## Pre-Flight Checks

- [x] DoR satisfied? Yes - plan is complete with acceptance tests
- [x] Access/secrets present? N/A - no secrets needed
- [x] Fixtures/data ready? N/A

**Note:** Plan references `ChatContainer` which doesn't exist. User approved creating minimal ChatContainer first.

## Execution Progress

### Task 0: Create Minimal ChatContainer Widget

**Status:** COMPLETED

Created `src/tunacode/ui/widgets/chat.py` with:
- `ChatContainer` class extending `VerticalScroll`
- `_current_stream` tracking for active streaming widget
- `_insertion_anchor` tracking for post-stream insertion point
- `write()` method for backward compat with RichLog
- `start_stream()`, `update_stream()`, `end_stream()`, `cancel_stream()` lifecycle methods
- `insert_before_stream()` for positioning tool panels correctly

Files created:
- `src/tunacode/ui/widgets/chat.py`

Files modified:
- `src/tunacode/ui/widgets/__init__.py` - added ChatContainer export

---

### Task 1: Add insertion anchor tracking to ChatContainer

**Status:** COMPLETED

Implemented in ChatContainer:
- `_insertion_anchor: Widget | None` attribute
- `end_stream()` captures finalized stream widget as anchor
- `cancel_stream()` captures previous sibling as anchor

---

### Task 2: Update insert_before_stream() to use insertion anchor

**Status:** COMPLETED

`insert_before_stream()` now handles three cases:
1. Active stream: insert before `_current_stream`
2. Stream ended: insert before `_insertion_anchor` (finalized message)
3. No context: append to end

---

### Task 3: Clear insertion anchor on new request

**Status:** COMPLETED

`start_stream()` clears `_insertion_anchor = None` to prevent stale positioning.
`clear()` also clears the anchor.

---

### Task 4: Handle cancel scenario insertion anchor

**Status:** COMPLETED

`cancel_stream()` finds the widget that was BEFORE the stream widget and sets it as anchor.
This allows late-arriving tool panels to insert at the correct position after cancel.

---

### Task 5: Wire into app.py

**Status:** COMPLETED

Changes to `src/tunacode/ui/app.py`:
- Replaced `RichLog` import with `ChatContainer`
- Added `ChatContainer` to widget imports
- Changed `self.rich_log: RichLog` to `self.chat_container: ChatContainer`
- Added `rich_log` property alias for backward compatibility
- Updated `compose()` to create `ChatContainer` instead of `RichLog`
- Added `chat_container.start_stream()` at request start
- Added `chat_container.end_stream()` in finally block before writing response
- Added `chat_container.cancel_stream()` in `action_cancel_stream()`
- Changed `on_tool_result_display()` to use `insert_before_stream()`

Files modified:
- `src/tunacode/ui/app.py`
- `src/tunacode/ui/welcome.py` - Updated type hint to use `WriteableLog` protocol

---

## Gate Results

- Tests: PASS (512 passed)
- Type checks: PASS (no new errors introduced)
- Linters: PASS (all checks passed)

## Files Changed Summary

| File | Action | Description |
|------|--------|-------------|
| `src/tunacode/ui/widgets/chat.py` | Created | ChatContainer widget with insertion tracking |
| `src/tunacode/ui/widgets/__init__.py` | Modified | Export ChatContainer |
| `src/tunacode/ui/app.py` | Modified | Replace RichLog with ChatContainer, wire up lifecycle |
| `src/tunacode/ui/welcome.py` | Modified | Update type hint for compatibility |

## Notes

- Branch: `fix/insert-before-stream-race`
- Rollback point: `5efc5423`
- End commit: `9be710d9`
- The `rich_log` property alias ensures backward compatibility for code that references `app.rich_log`

## Execution Report

**Date:** 2026-01-27
**Plan Source:** memory-bank/plan/reserch.md
**Start commit:** 5efc5423
**End commit:** 9be710d9
**Branch:** fix/insert-before-stream-race
**Final status:** SUCCESS

### Outcomes
- Tasks attempted: 6 (0 + 5 from plan)
- Tasks completed: 6
- Rollbacks: None
- All gates passed