fix(coding-agent): backported pi-mono changes (1feccfed..b21b42d0)

packages/ai:
- feat: expose provider responseId on AssistantMessage
- feat: lazy-load provider modules for faster startup
- fix: hash foreign Responses API tool call IDs exceeding 64-char limit
- fix: ignore null chunks in openai-completions streams
- fix: keep image tool results inline for Gemini 3+ and Antigravity
- fix: correct Bedrock Claude 4.6 context window to 200k
- fix: support prompt caching for Bedrock application inference profiles
- fix: add OpenRouter reasoning payload format
- fix: ignore placeholder Vertex API keys
- fix: skip AJV validation in restricted runtimes
- fix: Anthropic OAuth client injection and responseId extraction
- fix: Codex incomplete/failed response status handling

packages/agent:
- fix: defer steering until after tool execution completes

packages/tui:
- feat: namespaced keybinding IDs with KeybindingsManager conflict detection
- feat: configurable select list column sizing (#2154 by @markusylisiurunen)
- fix: stream truncateToWidth for large strings
- fix: skip Termux height redraws
- fix: stop evicting unrelated default keybindings
- fix: resolve raw backspace ambiguity on Windows Terminal
- fix: clear stale scrollback on session switch (#2155 by @Perlence)
- fix: remove trailing markdown block spacing (#2152 by @markusylisiurunen)

packages/coding-agent:
- feat: add resizable share sidebar (#2435 by @dmmulroy)
- feat: emit OSC 133 command-executed marker
- feat: reload custom themes from disk watcher
- feat: add --fork session flag
- feat: file mutation queue for serialized writes
- feat: initial message consolidation utility
- fix: keybindings migrated to namespaced IDs
- fix: resolve waitForRetry() race when auto-retry produces tool calls
- fix: handle slash-delimited /model refs
- fix: refresh active model after provider updates
- fix: extended transient error patterns for retry

packages/coding-agent/src/export/html/template.html

@@ -28,6 +28,7 @@
       <div class="tree-container" id="tree-container"></div>
       <div class="tree-status" id="tree-status"></div>
     </aside>
+    <div id="sidebar-resizer" role="separator" aria-orientation="vertical" aria-label="Resize session tree sidebar"></div>
     <main id="content">
       <div id="header-container"></div>
       <div id="messages"></div>