fix(subagent): return the chain's final result and mark unstarted steps

packages/coding-agent/src/features/step-subagent.ts

@@ -156,7 +156,12 @@ export interface StepSubagentResultRecord extends StepSubagentRunResult {
 	agent: string;
 	agentSource: StepAgentConfig["source"] | "unknown";
 	task: string;
-	status: "running" | "completed" | "failed" | "aborted";
+	/**
+	 * `queued`: not started yet (a later chain step, or a parallel task waiting
+	 * on maxConcurrency). `skipped`: a chain step that never started because an
+	 * earlier step did not complete.
+	 */
+	status: "queued" | "running" | "completed" | "failed" | "aborted" | "skipped";
 	step?: number;
 	worktreePath?: string;
 	worktreeBranch?: string;

packages/coding-agent/src/features/subagent/execute.ts

@@ -81,16 +81,47 @@ function makeEmptyResult(agent: string, task: string): StepSubagentResultRecord
 		agent,
 		agentSource: "unknown",
 		task,
-		status: "running",
+		status: "queued",
 		exitCode: -1,
 		messages: [],
 		stderr: "",
 		usage: emptyUsage(),
-		startedAt: Date.now(),
 		updatedAt: Date.now(),
 	};
 }
 
+function makeSkippedResult(record: StepSubagentResultRecord): StepSubagentResultRecord {
+	return { ...record, status: "skipped", updatedAt: Date.now() };
+}
+
+/**
+ * The parent model only sees `content`, never `details`, so a chain's text must
+ * carry both the outcome and the output that matters: the last completed step
+ * on success, the stopping step's error otherwise. Earlier step bodies stay in
+ * `details.results` instead of piling into the parent's context.
+ */
+function chainResultText(records: readonly StepSubagentResultRecord[]): string {
+	const steps = records.map((record, index) => `${index + 1}. ${record.agent}: ${record.status}`).join("\n");
+	const stopped = records.findIndex((record) => record.status !== "completed");
+	if (stopped === -1) {
+		const last = records.at(-1);
+		if (!last) return "(no output)";
+		return `Chain: ${records.length}/${records.length} steps completed\n${steps}\n\n### Final output (step ${records.length}, ${last.agent})\n\n${resultText(last)}`;
+	}
+	const failed = records[stopped];
+	const sections = [
+		`Chain stopped at step ${stopped + 1}/${records.length} (${failed.agent}: ${failed.status}); the chain did not complete.\n${steps}`,
+		`### Error (step ${stopped + 1}, ${failed.agent})\n\n${resultText(failed)}`,
+	];
+	const previous = stopped > 0 ? records[stopped - 1] : undefined;
+	if (previous) {
+		sections.push(
+			`### Last completed output (step ${stopped}, ${previous.agent})\n\n${truncateText(resultText(previous), 50_000)}`,
+		);
+	}
+	return sections.join("\n\n");
+}
+
 function resultDetailsText(details: StepSubagentDetails): string {
 	return details.results
 		.map((result) => {
@@ -320,6 +351,16 @@ export async function executeSubagent(
 			return failed;
 		}
 		reportCreated(agent, index);
+		// Flip the queued placeholder before spawning, so the step reads as running
+		// (with a clock) from the moment it is dispatched, not from its first event.
+		records[index] = {
+			...records[index],
+			agentSource: agent.source,
+			status: "running",
+			startedAt: Date.now(),
+			updatedAt: Date.now(),
+		};
+		emit(mode);
 		const baseCwd = path.resolve(ctx.cwd, task.cwd ?? ".");
 		let worktree: StepWorktreeLease | undefined;
 		let childCwd = baseCwd;
@@ -334,7 +375,7 @@ export async function executeSubagent(
 					worktreePath: worktree?.path,
 					worktreeBranch: worktree?.branch,
 				});
-				emit(parallel ? "parallel" : "single");
+				emit(mode);
 			};
 			const child = await options.runner({
 				agent,
@@ -394,7 +435,11 @@ export async function executeSubagent(
 			};
 			const record = await runOne(task, index);
 			previous = finalOutput(record.messages) || resultText(record);
-			if (record.status !== "completed") break;
+			if (record.status !== "completed") {
+				for (let rest = index + 1; rest < chain.length; rest++) records[rest] = makeSkippedResult(records[rest]);
+				emit(mode);
+				break;
+			}
 		}
 	} else await runOne(tasks[0], 0);
 	const finalDetails = buildDetails(mode, discovery, scope, records);
@@ -408,6 +453,7 @@ export async function executeSubagent(
 			`Parallel: ${success}/${records.length} succeeded\n\n${summaries.join("\n\n---\n\n")}`,
 		);
 	}
+	if (mode === "chain") return makeToolResult(finalDetails, chainResultText(records));
 	const record = records[0];
 	return makeToolResult(finalDetails, record ? resultText(record) : "(no output)");
 }

packages/coding-agent/src/features/subagent/lane-lifecycle.ts

@@ -81,7 +81,7 @@ function getLiveLaneSessions(sessionId: string | undefined): StepSubagentRpcSess
 }
 
 function laneStatusFromDetails(details: StepSubagentDetails): BackgroundAgentLane["status"] {
-	if (details.results.some((record) => record.status === "running")) {
+	if (details.results.some((record) => record.status === "running" || record.status === "queued")) {
 		return "running";
 	}
 	if (details.results.some((record) => record.status === "failed")) {

packages/coding-agent/src/features/subagent/rendering.ts

@@ -53,14 +53,31 @@ function formatElapsed(record: StepSubagentResultRecord): string {
 function statusIcon(status: StepSubagentResultRecord["status"], theme: Theme): string {
 	if (status === "running") return theme.fg("warning", "~");
 	if (status === "completed") return theme.fg("success", "\u2713");
+	if (status === "queued") return theme.fg("dim", "\u00b7");
+	if (status === "skipped") return theme.fg("dim", "-");
 	return theme.fg("error", "x");
 }
 
+function chainHeading(records: readonly StepSubagentResultRecord[]): string {
+	const index = records.findIndex(
+		(record) => record.status !== "completed" && record.status !== "queued" && record.status !== "skipped",
+	);
+	if (index !== -1) return `${records[index].status} at step ${index + 1}/${records.length}`;
+	const completed = records.filter((record) => record.status === "completed").length;
+	return completed === records.length
+		? `${completed}/${records.length} steps completed`
+		: `queued at step ${completed + 1}/${records.length}`;
+}
+
 function renderRecordSummary(record: StepSubagentResultRecord, theme: Theme): string {
 	const output =
 		record.activeText ||
 		finalOutput(record.messages) ||
-		(record.status === "running" ? "(running...)" : resultText(record));
+		(record.status === "running"
+			? "(running...)"
+			: record.status === "queued" || record.status === "skipped"
+				? `(${record.status})`
+				: resultText(record));
 	const lines = output.split(/\r?\n/u).filter((line) => line.trim().length > 0);
 	const preview = lines.slice(-COLLAPSED_OUTPUT_LINES).join("\n");
 	const omitted = Math.max(0, lines.length - COLLAPSED_OUTPUT_LINES);
@@ -201,10 +218,14 @@ export class SubagentListWidget implements Component {
 		const theme = this.theme;
 		const running = records.filter((record) => record.status === "running").length;
 		const completed = records.filter((record) => record.status === "completed").length;
-		const failed = records.length - running - completed;
+		const queued = records.filter((record) => record.status === "queued").length;
+		const skipped = records.filter((record) => record.status === "skipped").length;
+		const failed = records.length - running - completed - queued - skipped;
 		const summary = [`${completed}/${records.length} complete`];
 		if (running > 0) summary.push(`${running} running`);
+		if (queued > 0) summary.push(`${queued} queued`);
 		if (failed > 0) summary.push(`${failed} failed`);
+		if (skipped > 0) summary.push(`${skipped} skipped`);
 		const header = ` ${theme.fg("toolTitle", theme.bold("subagent"))} ${theme.fg("accent", summary.join(", "))}`;
 		const lines = [visibleWidth(header) > width ? truncateToWidth(header, width, "\u2026") : header];
 
@@ -255,11 +276,14 @@ export function renderSubagentResult(
 		return new Text(text?.type === "text" ? text.text : "(no output)", 0, 0);
 	}
 	const running = details.results.filter((record) => record.status === "running").length;
+	const queued = details.results.filter((record) => record.status === "queued").length;
 	const completed = details.results.filter((record) => record.status === "completed").length;
 	const heading =
 		details.mode === "parallel"
-			? `${completed}/${details.results.length} complete${running > 0 ? `, ${running} running` : ""}`
-			: (details.results[0]?.status ?? "done");
+			? `${completed}/${details.results.length} complete${running > 0 ? `, ${running} running` : ""}${queued > 0 ? `, ${queued} queued` : ""}`
+			: details.mode === "chain"
+				? chainHeading(details.results)
+				: (details.results[0]?.status ?? "done");
 	if (options.expanded) {
 		const container = new Container();
 		container.addChild(new Text(`${theme.bold("agent")} ${theme.fg("accent", heading)}`, 0, 0));