WIP: Add branch summarization abort support with loader and escape handler

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

@@ -146,6 +146,9 @@ export class AgentSession {
 	private _compactionAbortController: AbortController | undefined = undefined;
 	private _autoCompactionAbortController: AbortController | undefined = undefined;
 
+	// Branch summarization state
+	private _branchSummaryAbortController: AbortController | undefined = undefined;
+
 	// Retry state
 	private _retryAbortController: AbortController | undefined = undefined;
 	private _retryAttempt = 0;
@@ -998,6 +1001,13 @@ export class AgentSession {
 		this._autoCompactionAbortController?.abort();
 	}
 
+	/**
+	 * Cancel in-progress branch summarization.
+	 */
+	abortBranchSummary(): void {
+		this._branchSummaryAbortController?.abort();
+	}
+
 	/**
 	 * Check if compaction is needed and run it.
 	 * Called after agent_end and before prompt submission.
@@ -1572,7 +1582,7 @@ export class AgentSession {
 	async navigateTree(
 		targetId: string,
 		options: { summarize?: boolean; customInstructions?: string } = {},
-	): Promise<{ editorText?: string; cancelled: boolean }> {
+	): Promise<{ editorText?: string; cancelled: boolean; aborted?: boolean }> {
 		const oldLeafId = this.sessionManager.getLeafUuid();
 
 		// No-op if already at target
@@ -1625,7 +1635,7 @@ export class AgentSession {
 		};
 
 		// Set up abort controller for summarization
-		const abortController = new AbortController();
+		this._branchSummaryAbortController = new AbortController();
 		let hookSummary: { summary: string; details?: unknown } | undefined;
 		let fromHook = false;
 
@@ -1635,7 +1645,7 @@ export class AgentSession {
 				type: "session_before_tree",
 				preparation,
 				model: this.model!, // Checked above if summarize is true
-				signal: abortController.signal,
+				signal: this._branchSummaryAbortController.signal,
 			})) as SessionBeforeTreeResult | undefined;
 
 			if (result?.cancel) {
@@ -1655,11 +1665,16 @@ export class AgentSession {
 				summaryText = await this._generateBranchSummary(
 					entriesToSummarize,
 					options.customInstructions,
-					abortController.signal,
+					this._branchSummaryAbortController.signal,
 				);
-			} catch {
-				// Summarization failed - cancel navigation
-				return { cancelled: true };
+			} catch (error) {
+				this._branchSummaryAbortController = undefined;
+				// Check if aborted
+				if (error instanceof Error && (error.name === "AbortError" || error.message === "aborted")) {
+					return { cancelled: true, aborted: true };
+				}
+				// Re-throw actual errors so UI can display them
+				throw error;
 			}
 		} else if (hookSummary) {
 			summaryText = hookSummary.summary;
@@ -1718,6 +1733,7 @@ export class AgentSession {
 		// Emit to custom tools
 		await this._emitToolSessionEvent("tree", this.sessionFile);
 
+		this._branchSummaryAbortController = undefined;
 		return { editorText, cancelled: false };
 	}
 

packages/coding-agent/src/modes/interactive/interactive-mode.ts

@@ -1637,8 +1637,32 @@ export class InteractiveMode {
 						"Create a summary of the branch you're leaving?",
 					);
 
+					// Set up escape handler and loader if summarizing
+					let summaryLoader: Loader | undefined;
+					const originalOnEscape = this.editor.onEscape;
+
+					if (wantsSummary) {
+						this.editor.onEscape = () => {
+							this.session.abortBranchSummary();
+						};
+						this.chatContainer.addChild(new Spacer(1));
+						summaryLoader = new Loader(
+							this.ui,
+							(spinner) => theme.fg("accent", spinner),
+							(text) => theme.fg("muted", text),
+							"Summarizing branch... (esc to cancel)",
+						);
+						this.statusContainer.addChild(summaryLoader);
+						this.ui.requestRender();
+					}
+
 					try {
 						const result = await this.session.navigateTree(entryId, { summarize: wantsSummary });
+
+						if (result.aborted) {
+							this.showStatus("Branch summarization cancelled");
+							return;
+						}
 						if (result.cancelled) {
 							this.showStatus("Navigation cancelled");
 							return;
@@ -1653,6 +1677,12 @@ export class InteractiveMode {
 						this.showStatus("Navigated to selected point");
 					} catch (error) {
 						this.showError(error instanceof Error ? error.message : String(error));
+					} finally {
+						if (summaryLoader) {
+							summaryLoader.stop();
+							this.statusContainer.clear();
+						}
+						this.editor.onEscape = originalOnEscape;
 					}
 				},
 				() => {