Use exhaustive switch on message.role throughout coding-agent

- addMessageToChat: exhaustive switch for all AgentMessage roles
- renderSessionContext: delegates to addMessageToChat, special handling for assistant tool calls and tool results
- export-html formatMessage: exhaustive switch for all AgentMessage roles
- Removed isHookMessage, isBashExecutionMessage type guards in favor of role checks
- Fixed imports and removed unused getLatestCompactionEntry

packages/coding-agent/src/modes/interactive/components/compaction-summary-message.ts

@@ -0,0 +1,51 @@
+import { Container, Markdown, Spacer, Text } from "@mariozechner/pi-tui";
+import type { CompactionSummaryMessage } from "packages/coding-agent/src/core/messages.js";
+import { getMarkdownTheme, theme } from "../theme/theme.js";
+
+/**
+ * Component that renders a compaction message with collapsed/expanded state.
+ * Collapsed: shows "Context compacted from X tokens"
+ * Expanded: shows the full summary rendered as markdown (like a user message)
+ */
+export class CompactionSummaryMessageComponent extends Container {
+	private expanded = false;
+	private message: CompactionSummaryMessage;
+
+	constructor(message: CompactionSummaryMessage) {
+		super();
+		this.message = message;
+		this.updateDisplay();
+	}
+
+	setExpanded(expanded: boolean): void {
+		this.expanded = expanded;
+		this.updateDisplay();
+	}
+
+	private updateDisplay(): void {
+		this.clear();
+
+		if (this.expanded) {
+			// Show header + summary as markdown (like user message)
+			this.addChild(new Spacer(1));
+			const header = `**Context compacted from ${this.message.tokensBefore.toLocaleString()} tokens**\n\n`;
+			this.addChild(
+				new Markdown(header + this.message.summary, 1, 1, getMarkdownTheme(), {
+					bgColor: (text: string) => theme.bg("userMessageBg", text),
+					color: (text: string) => theme.fg("userMessageText", text),
+				}),
+			);
+			this.addChild(new Spacer(1));
+		} else {
+			// Collapsed: simple text in warning color with token count
+			const tokenStr = this.message.tokensBefore.toLocaleString();
+			this.addChild(
+				new Text(
+					theme.fg("warning", `Earlier messages compacted from ${tokenStr} tokens (ctrl+o to expand)`),
+					1,
+					1,
+				),
+			);
+		}
+	}
+}