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/cli/args.ts

@@ -28,6 +28,7 @@ export interface Args {
 	mode?: Mode;
 	noSession?: boolean;
 	sessionDir?: string;
+	fork?: string;
 	models?: string[];
 	tools?: string[];
 	noTools?: boolean;
@@ -79,6 +80,8 @@ export function parseArgs(args: string[], extensionFlags?: Map<string, { type: "
 			} else {
 				result.resume = true;
 			}
+		} else if (arg === "--fork" && i + 1 < args.length) {
+			result.fork = args[++i];
 		} else if (arg === "--provider" && i + 1 < args.length) {
 			result.provider = args[++i];
 		} else if (arg === "--model" && i + 1 < args.length) {

packages/coding-agent/src/cli/initial-message.ts

@@ -0,0 +1,58 @@
+import type { ImageContent } from "@oh-my-pi/pi-ai";
+import type { Args } from "./args";
+
+export interface InitialMessageInput {
+	parsed: Args;
+	fileText?: string;
+	fileImages?: ImageContent[];
+	stdinContent?: string;
+}
+
+export interface InitialMessageResult {
+	initialMessage?: string;
+	initialImages?: ImageContent[];
+}
+
+/**
+ * Combine stdin content, @file text, and the first CLI message into a single
+ * initial prompt for non-interactive mode.
+ */
+export function buildInitialMessage({
+	parsed,
+	fileText,
+	fileImages,
+	stdinContent,
+}: InitialMessageInput): InitialMessageResult {
+	const hasInitialContext = stdinContent !== undefined || fileText !== undefined || (fileImages?.length ?? 0) > 0;
+	if (!hasInitialContext) {
+		return {
+			initialImages: undefined,
+		};
+	}
+
+	let body = "";
+	if (fileText !== undefined) {
+		body += fileText;
+	}
+
+	if (parsed.messages.length > 0) {
+		body += parsed.messages[0];
+		parsed.messages.shift();
+	}
+
+	const initialMessage =
+		stdinContent !== undefined
+			? body.length > 0
+				? `${stdinContent}\n${body}`
+				: stdinContent
+			: body.length > 0
+				? body
+				: fileImages && fileImages.length > 0
+					? ""
+					: undefined;
+
+	return {
+		initialMessage,
+		initialImages: fileImages && fileImages.length > 0 ? fileImages : undefined,
+	};
+}