fix(ai,coding-agent): preserve non-vision image placeholders closes #3429

packages/coding-agent/src/core/agent-session-runtime.ts

@@ -98,7 +98,7 @@ export class AgentSessionRuntime {
 		targetSessionFile?: string,
 	): Promise<{ cancelled: boolean }> {
 		const runner = this.session.extensionRunner;
-		if (!runner?.hasHandlers("session_before_switch")) {
+		if (!runner.hasHandlers("session_before_switch")) {
 			return { cancelled: false };
 		}
 
@@ -115,7 +115,7 @@ export class AgentSessionRuntime {
 		options: { position: "before" | "at" },
 	): Promise<{ cancelled: boolean }> {
 		const runner = this.session.extensionRunner;
-		if (!runner?.hasHandlers("session_before_fork")) {
+		if (!runner.hasHandlers("session_before_fork")) {
 			return { cancelled: false };
 		}
 

packages/coding-agent/src/core/agent-session.ts

@@ -79,7 +79,7 @@ import { createSyntheticSourceInfo, type SourceInfo } from "./source-info.js";
 import { buildSystemPrompt } from "./system-prompt.js";
 import { type BashOperations, createLocalBashOperations } from "./tools/bash.js";
 import { createAllToolDefinitions } from "./tools/index.js";
-import { createToolDefinitionFromAgentTool, wrapToolDefinition } from "./tools/tool-definition-wrapper.js";
+import { createToolDefinitionFromAgentTool } from "./tools/tool-definition-wrapper.js";
 
 // ============================================================================
 // Skill Block Parsing
@@ -269,7 +269,7 @@ export class AgentSession {
 	private _pendingBashMessages: BashExecutionMessage[] = [];
 
 	// Extension system
-	private _extensionRunner: ExtensionRunner | undefined = undefined;
+	private _extensionRunner!: ExtensionRunner;
 	private _turnIndex = 0;
 
 	private _resourceLoader: ResourceLoader;
@@ -365,7 +365,7 @@ export class AgentSession {
 	private _installAgentToolHooks(): void {
 		this.agent.beforeToolCall = async ({ toolCall, args }) => {
 			const runner = this._extensionRunner;
-			if (!runner?.hasHandlers("tool_call")) {
+			if (!runner.hasHandlers("tool_call")) {
 				return undefined;
 			}
 
@@ -388,7 +388,7 @@ export class AgentSession {
 
 		this.agent.afterToolCall = async ({ toolCall, args, result, isError }) => {
 			const runner = this._extensionRunner;
-			if (!runner?.hasHandlers("tool_result")) {
+			if (!runner.hasHandlers("tool_result")) {
 				return undefined;
 			}
 
@@ -604,8 +604,6 @@ export class AgentSession {
 
 	/** Emit extension events based on agent events */
 	private async _emitExtensionEvent(event: AgentEvent): Promise<void> {
-		if (!this._extensionRunner) return;
-
 		if (event.type === "agent_start") {
 			this._turnIndex = 0;
 			await this._extensionRunner.emit({ type: "agent_start" });
@@ -949,7 +947,7 @@ export class AgentSession {
 			// Emit input event for extension interception (before skill/template expansion)
 			let currentText = text;
 			let currentImages = options?.images;
-			if (this._extensionRunner?.hasHandlers("input")) {
+			if (this._extensionRunner.hasHandlers("input")) {
 				const inputResult = await this._extensionRunner.emitInput(
 					currentText,
 					currentImages,
@@ -1042,33 +1040,31 @@ export class AgentSession {
 			this._pendingNextTurnMessages = [];
 
 			// Emit before_agent_start extension event
-			if (this._extensionRunner) {
-				const result = await this._extensionRunner.emitBeforeAgentStart(
-					expandedText,
-					currentImages,
-					this._baseSystemPrompt,
-				);
-				// Add all custom messages from extensions
-				if (result?.messages) {
-					for (const msg of result.messages) {
-						messages.push({
-							role: "custom",
-							customType: msg.customType,
-							content: msg.content,
-							display: msg.display,
-							details: msg.details,
-							timestamp: Date.now(),
-						});
-					}
-				}
-				// Apply extension-modified system prompt, or reset to base
-				if (result?.systemPrompt) {
-					this.agent.state.systemPrompt = result.systemPrompt;
-				} else {
-					// Ensure we're using the base prompt (in case previous turn had modifications)
-					this.agent.state.systemPrompt = this._baseSystemPrompt;
+			const result = await this._extensionRunner.emitBeforeAgentStart(
+				expandedText,
+				currentImages,
+				this._baseSystemPrompt,
+			);
+			// Add all custom messages from extensions
+			if (result?.messages) {
+				for (const msg of result.messages) {
+					messages.push({
+						role: "custom",
+						customType: msg.customType,
+						content: msg.content,
+						display: msg.display,
+						details: msg.details,
+						timestamp: Date.now(),
+					});
 				}
 			}
+			// Apply extension-modified system prompt, or reset to base
+			if (result?.systemPrompt) {
+				this.agent.state.systemPrompt = result.systemPrompt;
+			} else {
+				// Ensure we're using the base prompt (in case previous turn had modifications)
+				this.agent.state.systemPrompt = this._baseSystemPrompt;
+			}
 		} catch (error) {
 			preflightResult?.(false);
 			throw error;
@@ -1087,8 +1083,6 @@ export class AgentSession {
 	 * Try to execute an extension command. Returns true if command was found and executed.
 	 */
 	private async _tryExecuteExtensionCommand(text: string): Promise<boolean> {
-		if (!this._extensionRunner) return false;
-
 		// Parse command name and args
 		const spaceIndex = text.indexOf(" ");
 		const commandName = spaceIndex === -1 ? text.slice(1) : text.slice(1, spaceIndex);
@@ -1136,7 +1130,7 @@ export class AgentSession {
 			return args ? `${skillBlock}\n\n${args}` : skillBlock;
 		} catch (err) {
 			// Emit error like extension commands do
-			this._extensionRunner?.emitError({
+			this._extensionRunner.emitError({
 				extensionPath: skill.filePath,
 				event: "skill_expansion",
 				error: err instanceof Error ? err.message : String(err),
@@ -1224,8 +1218,6 @@ export class AgentSession {
 	 * Throw an error if the text is an extension command.
 	 */
 	private _throwIfExtensionCommand(text: string): void {
-		if (!this._extensionRunner) return;
-
 		const spaceIndex = text.indexOf(" ");
 		const commandName = spaceIndex === -1 ? text.slice(1) : text.slice(1, spaceIndex);
 		const command = this._extensionRunner.getCommand(commandName);
@@ -1376,7 +1368,6 @@ export class AgentSession {
 		previousModel: Model<any> | undefined,
 		source: "set" | "cycle" | "restore",
 	): Promise<void> {
-		if (!this._extensionRunner) return;
 		if (modelsAreEqual(previousModel, nextModel)) return;
 		await this._extensionRunner.emit({
 			type: "model_select",
@@ -1628,7 +1619,7 @@ export class AgentSession {
 			let extensionCompaction: CompactionResult | undefined;
 			let fromExtension = false;
 
-			if (this._extensionRunner?.hasHandlers("session_before_compact")) {
+			if (this._extensionRunner.hasHandlers("session_before_compact")) {
 				const result = (await this._extensionRunner.emit({
 					type: "session_before_compact",
 					preparation,
@@ -1886,7 +1877,7 @@ export class AgentSession {
 			let extensionCompaction: CompactionResult | undefined;
 			let fromExtension = false;
 
-			if (this._extensionRunner?.hasHandlers("session_before_compact")) {
+			if (this._extensionRunner.hasHandlers("session_before_compact")) {
 				const extensionResult = (await this._extensionRunner.emit({
 					type: "session_before_compact",
 					preparation,
@@ -2038,15 +2029,13 @@ export class AgentSession {
 			this._extensionErrorListener = bindings.onError;
 		}
 
-		if (this._extensionRunner) {
-			this._applyExtensionBindings(this._extensionRunner);
-			await this._extensionRunner.emit(this._sessionStartEvent);
-			await this.extendResourcesFromExtensions(this._sessionStartEvent.reason === "reload" ? "reload" : "startup");
-		}
+		this._applyExtensionBindings(this._extensionRunner);
+		await this._extensionRunner.emit(this._sessionStartEvent);
+		await this.extendResourcesFromExtensions(this._sessionStartEvent.reason === "reload" ? "reload" : "startup");
 	}
 
 	private async extendResourcesFromExtensions(reason: "startup" | "reload"): Promise<void> {
-		if (!this._extensionRunner?.hasHandlers("resources_discover")) {
+		if (!this._extensionRunner.hasHandlers("resources_discover")) {
 			return;
 		}
 
@@ -2233,7 +2222,7 @@ export class AgentSession {
 		const previousRegistryNames = new Set(this._toolRegistry.keys());
 		const previousActiveToolNames = this.getActiveToolNames();
 
-		const registeredTools = this._extensionRunner?.getAllRegisteredTools() ?? [];
+		const registeredTools = this._extensionRunner.getAllRegisteredTools();
 		const allCustomTools = [
 			...registeredTools,
 			...this._customTools.map((definition) => ({
@@ -2273,16 +2262,17 @@ export class AgentSession {
 				})
 				.filter((entry): entry is readonly [string, string[]] => entry !== undefined),
 		);
-		const wrappedExtensionTools = this._extensionRunner
-			? wrapRegisteredTools(allCustomTools, this._extensionRunner)
-			: [];
-
-		const toolRegistry = new Map(
-			Array.from(this._baseToolDefinitions.values()).map((definition) => [
-				definition.name,
-				wrapToolDefinition(definition),
-			]),
+		const runner = this._extensionRunner;
+		const wrappedExtensionTools = wrapRegisteredTools(allCustomTools, runner);
+		const wrappedBuiltInTools = wrapRegisteredTools(
+			Array.from(this._baseToolDefinitions.values()).map((definition) => ({
+				definition,
+				sourceInfo: createSyntheticSourceInfo(`<builtin:${definition.name}>`, { source: "builtin" }),
+			})),
+			runner,
 		);
+
+		const toolRegistry = new Map(wrappedBuiltInTools.map((tool) => [tool.name, tool]));
 		for (const tool of wrappedExtensionTools as AgentTool[]) {
 			toolRegistry.set(tool.name, tool);
 		}
@@ -2337,25 +2327,18 @@ export class AgentSession {
 			}
 		}
 
-		const hasExtensions = extensionsResult.extensions.length > 0;
-		const hasCustomTools = this._customTools.length > 0;
-		this._extensionRunner =
-			hasExtensions || hasCustomTools
-				? new ExtensionRunner(
-						extensionsResult.extensions,
-						extensionsResult.runtime,
-						this._cwd,
-						this.sessionManager,
-						this._modelRegistry,
-					)
-				: undefined;
+		this._extensionRunner = new ExtensionRunner(
+			extensionsResult.extensions,
+			extensionsResult.runtime,
+			this._cwd,
+			this.sessionManager,
+			this._modelRegistry,
+		);
 		if (this._extensionRunnerRef) {
 			this._extensionRunnerRef.current = this._extensionRunner;
 		}
-		if (this._extensionRunner) {
-			this._bindExtensionCore(this._extensionRunner);
-			this._applyExtensionBindings(this._extensionRunner);
-		}
+		this._bindExtensionCore(this._extensionRunner);
+		this._applyExtensionBindings(this._extensionRunner);
 
 		const defaultActiveToolNames = this._baseToolsOverride
 			? Object.keys(this._baseToolsOverride)
@@ -2368,8 +2351,8 @@ export class AgentSession {
 	}
 
 	async reload(): Promise<void> {
-		const previousFlagValues = this._extensionRunner?.getFlagValues();
-		await this._extensionRunner?.emit({ type: "session_shutdown" });
+		const previousFlagValues = this._extensionRunner.getFlagValues();
+		await this._extensionRunner.emit({ type: "session_shutdown" });
 		await this.settingsManager.reload();
 		resetApiProviders();
 		await this._resourceLoader.reload();
@@ -2384,7 +2367,7 @@ export class AgentSession {
 			this._extensionCommandContextActions ||
 			this._extensionShutdownHandler ||
 			this._extensionErrorListener;
-		if (this._extensionRunner && hasBindings) {
+		if (hasBindings) {
 			await this._extensionRunner.emit({ type: "session_start", reason: "reload" });
 			await this.extendResourcesFromExtensions("reload");
 		}
@@ -2713,7 +2696,7 @@ export class AgentSession {
 		let fromExtension = false;
 
 		// Emit session_before_tree event
-		if (this._extensionRunner?.hasHandlers("session_before_tree")) {
+		if (this._extensionRunner.hasHandlers("session_before_tree")) {
 			const result = (await this._extensionRunner.emit({
 				type: "session_before_tree",
 				preparation,
@@ -2827,15 +2810,13 @@ export class AgentSession {
 		this.agent.state.messages = sessionContext.messages;
 
 		// Emit session_tree event
-		if (this._extensionRunner) {
-			await this._extensionRunner.emit({
-				type: "session_tree",
-				newLeafId: this.sessionManager.getLeafId(),
-				oldLeafId,
-				summaryEntry,
-				fromExtension: summaryText ? fromExtension : undefined,
-			});
-		}
+		await this._extensionRunner.emit({
+			type: "session_tree",
+			newLeafId: this.sessionManager.getLeafId(),
+			oldLeafId,
+			summaryEntry,
+			fromExtension: summaryText ? fromExtension : undefined,
+		});
 
 		// Emit to custom tools
 
@@ -3067,13 +3048,13 @@ export class AgentSession {
 	 * Check if extensions have handlers for a specific event type.
 	 */
 	hasExtensionHandlers(eventType: string): boolean {
-		return this._extensionRunner?.hasHandlers(eventType) ?? false;
+		return this._extensionRunner.hasHandlers(eventType);
 	}
 
 	/**
 	 * Get the extension runner (for setting UI context and error handlers).
 	 */
-	get extensionRunner(): ExtensionRunner | undefined {
+	get extensionRunner(): ExtensionRunner {
 		return this._extensionRunner;
 	}
 }

packages/coding-agent/src/core/extensions/wrapper.ts

@@ -6,7 +6,7 @@
  */
 
 import type { AgentTool } from "@mariozechner/pi-agent-core";
-import { wrapToolDefinition } from "../tools/tool-definition-wrapper.js";
+import { wrapToolDefinition, wrapToolDefinitions } from "../tools/tool-definition-wrapper.js";
 import type { ExtensionRunner } from "./runner.js";
 import type { RegisteredTool } from "./types.js";
 
@@ -23,5 +23,8 @@ export function wrapRegisteredTool(registeredTool: RegisteredTool, runner: Exten
  * Uses the runner's createContext() for consistent context across tools and event handlers.
  */
 export function wrapRegisteredTools(registeredTools: RegisteredTool[], runner: ExtensionRunner): AgentTool[] {
-	return registeredTools.map((rt) => wrapRegisteredTool(rt, runner));
+	return wrapToolDefinitions(
+		registeredTools.map((registeredTool) => registeredTool.definition),
+		() => runner.createContext(),
+	);
 }

packages/coding-agent/src/core/tools/read.ts

@@ -1,5 +1,5 @@
 import type { AgentTool } from "@mariozechner/pi-agent-core";
-import type { ImageContent, TextContent } from "@mariozechner/pi-ai";
+import type { Api, ImageContent, Model, TextContent } from "@mariozechner/pi-ai";
 import { Text } from "@mariozechner/pi-tui";
 import { type Static, Type } from "@sinclair/typebox";
 import { constants } from "fs";
@@ -78,6 +78,13 @@ function trimTrailingEmptyLines(lines: string[]): string[] {
 	return lines.slice(0, end);
 }
 
+function getNonVisionImageNote(model: Model<Api> | undefined): string | undefined {
+	if (!model || model.input.includes("image")) {
+		return undefined;
+	}
+	return "[Current model does not support images. The image will be omitted from this request.]";
+}
+
 function formatReadResult(
 	args: { path?: string; file_path?: string; offset?: number; limit?: number } | undefined,
 	result: { content: (TextContent | ImageContent)[]; details?: ReadToolDetails },
@@ -129,7 +136,7 @@ export function createReadToolDefinition(
 			{ path, offset, limit }: { path: string; offset?: number; limit?: number },
 			signal?: AbortSignal,
 			_onUpdate?,
-			_ctx?,
+			ctx?,
 		) {
 			const absolutePath = resolveReadPath(path, cwd);
 			return new Promise<{ content: (TextContent | ImageContent)[]; details: ReadToolDetails | undefined }>(
@@ -153,6 +160,7 @@ export function createReadToolDefinition(
 							const mimeType = ops.detectImageMimeType ? await ops.detectImageMimeType(absolutePath) : undefined;
 							let content: (TextContent | ImageContent)[];
 							let details: ReadToolDetails | undefined;
+							const nonVisionImageNote = getNonVisionImageNote(ctx?.model);
 							if (mimeType) {
 								// Read image as binary.
 								const buffer = await ops.readFile(absolutePath);
@@ -161,24 +169,24 @@ export function createReadToolDefinition(
 									// Resize image if needed before sending it back to the model.
 									const resized = await resizeImage({ type: "image", data: base64, mimeType });
 									if (!resized) {
-										content = [
-											{
-												type: "text",
-												text: `Read image file [${mimeType}]\n[Image omitted: could not be resized below the inline image size limit.]`,
-											},
-										];
+										let textNote = `Read image file [${mimeType}]\n[Image omitted: could not be resized below the inline image size limit.]`;
+										if (nonVisionImageNote) textNote += `\n${nonVisionImageNote}`;
+										content = [{ type: "text", text: textNote }];
 									} else {
 										const dimensionNote = formatDimensionNote(resized);
 										let textNote = `Read image file [${resized.mimeType}]`;
 										if (dimensionNote) textNote += `\n${dimensionNote}`;
+										if (nonVisionImageNote) textNote += `\n${nonVisionImageNote}`;
 										content = [
 											{ type: "text", text: textNote },
 											{ type: "image", data: resized.data, mimeType: resized.mimeType },
 										];
 									}
 								} else {
+									let textNote = `Read image file [${mimeType}]`;
+									if (nonVisionImageNote) textNote += `\n${nonVisionImageNote}`;
 									content = [
-										{ type: "text", text: `Read image file [${mimeType}]` },
+										{ type: "text", text: textNote },
 										{ type: "image", data: base64, mimeType },
 									];
 								}