Merge session/42d677c5-chat-debug-panel: Debug panel with ScrollListener

Implemented chat command debug panel with principled Pinax abstractions.

FEATURES:
- --debug-panel flag for chat command (default: true)
- Fixed 65-column right panel, flexible content area
- SemanticLogger integration via SidePanelAppender
- ANSI-aware text wrapping (Pinax::Text)
- Panel redraws on scroll and input resize

ARCHITECTURE:
- ScrollListener protocol for decoupled scroll events
- Layout::Composed emits events, SidePanel implements protocol
- Clean separation keeps Pinax gem-extractable

NEW FILES:
- lib/pinax/layout/scroll_listener.rb
- lib/pinax/text.rb (wrap, truncate, visible_length, strip_ansi)
- lib/autopax/cli/side_panel_appender.rb

TESTS: 926 examples, 0 failures

Session: 42d677c5-6fc9-4bf4-ba21-f3a1e67ebcbd
Branch: session/42d677c5-chat-debug-panel
Commits: 17

🤖 Generated with [Claude Code](https://claude.com/claude-code)

Co-Authored-By: Claude-42d677c5 <claude@v2.io>

Author: josephwecker

HANDOFF.md

@@ -1,75 +1,62 @@
 # Handoff Notes for Next Agent
 
 **Last Updated:** 2025-12-19
-**Current State:** Side panel implementation COMPLETE - ready for review/merge
+**Current State:** Debug panel integration COMPLETE and merged
 
 ---
 
-## Completed: Pinax Side Panel Implementation
+## Recently Completed: Chat Command Debug Panel (Session 42d677c5)
 
-**Worktree:** `/Users/josephwecker-v2/src/autopax-worktrees/42d677c5-pinax-side-panel`
-**Branch:** `session/42d677c5-pinax-side-panel`
+### Summary
 
-### What Was Built
+Implemented a debug panel for the chat command that shows telemetry (API timing,
+token counts, tool execution) in a right-side panel. The panel uses a principled
+ScrollListener protocol for proper abstraction.
 
-A fixed right-side debug panel for terminal UIs that preserves native scrollback.
+### Key Features
 
-**Pattern: Redraw-After-Scroll**
-```
-Before scroll:  Clear top N rows of panel area (just spaces)
-Scroll:         Native DECSTBM scroll (spaces go into scrollback - clean!)
-After scroll:   Redraw the panel
-```
-
-Tested and working in Ghostty, Kitty, and iTerm.
-
-### New Files
-
-- `lib/pinax/side_panel.rb` - Main SidePanel class (buffer, config, public API)
-- `lib/pinax/side_panel/rendering.rb` - Extracted rendering methods
-
-### Changed Files
+- `--debug-panel` flag (default: true, `--no-debug-panel` to disable)
+- Fixed 65-column panel on right side (content area flexes)
+- SemanticLogger integration routes all log output to panel
+- ANSI-aware text wrapping via `Pinax::Text`
+- Panel redraws properly on scroll and input resize
 
-- `lib/pinax/layout/composed.rb` - Added side_panel integration
-- `lib/pinax/layout/region_builder.rb` - Uses content_width for history region
-- `spec/pinax/side_panel_spec.rb` - 22 specs for SidePanel
-- `spec/pinax/layout/composed_spec.rb` - 11 new specs for side panel integration
+### Architecture: ScrollListener Protocol
 
-### Usage
+The side panel uses a clean observer pattern for scroll events:
 
 ```ruby
-layout = Pinax::Layout::Composed.new
-layout.setup!(
-  input_lines: 4,
-  content_width: 80,              # Wrap history at 80 cols
-  side_panel: { header: 'Debug' } # Create panel in remaining space
-)
-
-layout << "[user] Hello"          # Auto-clears panel, scrolls, redraws
-layout.side_panel.log("API: 203ms") # Add log entries
+module Pinax::Layout::ScrollListener
+  def before_scroll(lines)  # Called before content scrolls
+  def after_scroll          # Called after content scrolled
+end
 ```
 
----
+`Layout::Composed` emits scroll events; `SidePanel` implements the protocol.
+This keeps Pinax gem-extractable with no Autopax dependencies.
 
-## Test Status
+### New Files
 
-```bash
-./autopax dev test    # 916 examples, 0 failures (32 new tests)
-./autopax dev format  # All side_panel files pass rubocop
-```
+- `lib/pinax/layout/scroll_listener.rb` - Scroll event protocol
+- `lib/pinax/text.rb` - ANSI-aware text utilities (wrap, truncate, visible_length)
+- `lib/autopax/cli/side_panel_appender.rb` - SemanticLogger subscriber for panel
+
+### Test Status
+
+926 examples, 0 failures
 
 ---
 
 ## What's Next
 
-1. **Optional chat command integration** - Add `--debug-panel` flag
-2. **Stderr routing** - Convenience method to redirect warnings to panel
+See OPERATA.md for current priorities. The chat command integration is a good
+foundation for future telemetry and debugging features.
 
 ---
 
-## Proof of Concept Scripts (for reference)
+## Demo Scripts
 
 ```bash
-./bin/redraw-panel-test   # Working demo of the pattern
-./bin/decslrm-test        # DECSLRM approach (loses scrollback - rejected)
+./bin/side-panel-demo      # Official Pinax side panel demo
+./bin/layout-composed-demo # Basic layout demo (no panel)
 ```

bin/side-panel-demo

@@ -35,7 +35,7 @@ begin
   layout << 'Demo complete! Press Ctrl+C to exit.'
   layout << 'Then scroll up to verify scrollback is clean.'
 
-  sleep until false
+  loop { sleep }
 rescue Interrupt
   # Clean exit
 ensure

lib/autopax/cli/side_panel_appender.rb

@@ -0,0 +1,81 @@
+require 'semantic_logger'
+require 'paint'
+require 'pinax/text'
+
+# SemanticLogger appender that routes log output to a Pinax::SidePanel.
+#
+# Uses the same colored format as CLI::Logger interactive mode, with text
+# wrapping to fit the panel width. Replaces stderr logging in TUI mode.
+#
+# ## Usage
+#
+# ```ruby
+# # Clear existing appenders and add panel appender
+# SemanticLogger.clear_appenders!
+# appender = CLI::SidePanelAppender.new(panel: @layout.side_panel)
+# SemanticLogger.add_appender(appender: appender)
+# ```
+#
+class CLI::SidePanelAppender < SemanticLogger::Subscriber
+  attr_reader :panel
+
+  # @param panel [Pinax::SidePanel] The side panel to log to
+  # @param level [Symbol] Minimum log level (default: :debug)
+  def initialize(panel:, level: :debug, **args)
+    @panel = panel
+    super(level: level, **args)
+  end
+
+  # Called by SemanticLogger for each log entry.
+  # Formats using CLI::Logger style and wraps to panel width.
+  #
+  # Method name required by SemanticLogger::Subscriber interface.
+  # rubocop:disable Naming/PredicateMethod
+  def log(log)
+    return false unless should_log?(log)
+
+    formatted = format_log(log)
+    wrapped_lines = Pinax::Text.wrap(formatted, panel.width - 2)
+
+    wrapped_lines.each { |line| panel.log(line, timestamp: false) }
+    panel.redraw!
+    true
+  end
+
+  # Flush is a no-op for panel appender (panel is always immediate).
+  #
+  # Method name required by SemanticLogger::Subscriber interface.
+  def flush
+    true
+  end
+  # rubocop:enable Naming/PredicateMethod
+
+  private
+
+  # Format log entry using CLI::Logger's interactive format (colored).
+  def format_log(log)
+    prefix = level_prefix(log.level)
+    "#{prefix} #{log.message}#{payload_string(log)}"
+  end
+
+  # Colored level prefix matching CLI::Logger interactive mode.
+  def level_prefix(level)
+    prefix, color = case level
+                    when :debug then ["[\uf46f debug]→", :cyan]
+                    when :info  then ["[\uea74  info]→", :green]
+                    when :warn  then ['[⚠  warn]→', :yellow]
+                    when :error then ['[✗ error]→', :red]
+                    when :fatal then ['[✗ FATAL]→', :red]
+                    else ["[#{level}]:", :white]
+                    end
+    Paint[prefix, color]
+  end
+
+  # Format payload key-value pairs matching CLI::Logger style.
+  def payload_string(log)
+    return '' unless log.payload&.any?
+
+    pairs = log.payload.map { |k, v| "#{k}=#{v.inspect}" }
+    " (#{pairs.join(', ')})"
+  end
+end