diff --git a/packages/coding-agent/CHANGELOG.md b/packages/coding-agent/CHANGELOG.md
index 2c6d4bdf..5366ead3 100644
--- a/packages/coding-agent/CHANGELOG.md
+++ b/packages/coding-agent/CHANGELOG.md
@@ -8,6 +8,7 @@
 
 ### Fixed
 
+- Fixed `switchSession()` appending spurious `thinking_level_change` entry to session log on resume. `setThinkingLevel()` is now idempotent. ([#1118](https://github.com/badlogic/pi-mono/issues/1118))
 - Fixed clipboard image paste on WSL2/WSLg writing invalid PNG files when clipboard provides `image/bmp` format. BMP images are now converted to PNG before saving. ([#1112](https://github.com/badlogic/pi-mono/pull/1112) by [@lightningRalf](https://github.com/lightningRalf))
 
 ## [0.50.7] - 2026-01-31
diff --git a/packages/coding-agent/src/core/agent-session.ts b/packages/coding-agent/src/core/agent-session.ts
index 21caa860..f85ce35c 100644
--- a/packages/coding-agent/src/core/agent-session.ts
+++ b/packages/coding-agent/src/core/agent-session.ts
@@ -1236,14 +1236,21 @@ export class AgentSession {
 	/**
 	 * Set thinking level.
 	 * Clamps to model capabilities based on available thinking levels.
-	 * Saves to session and settings.
+	 * Saves to session and settings only if the level actually changes.
 	 */
 	setThinkingLevel(level: ThinkingLevel): void {
 		const availableLevels = this.getAvailableThinkingLevels();
 		const effectiveLevel = availableLevels.includes(level) ? level : this._clampThinkingLevel(level, availableLevels);
+
+		// Only persist if actually changing
+		const isChanging = effectiveLevel !== this.agent.state.thinkingLevel;
+
 		this.agent.setThinkingLevel(effectiveLevel);
-		this.sessionManager.appendThinkingLevelChange(effectiveLevel);
-		this.settingsManager.setDefaultThinkingLevel(effectiveLevel);
+
+		if (isChanging) {
+			this.sessionManager.appendThinkingLevelChange(effectiveLevel);
+			this.settingsManager.setDefaultThinkingLevel(effectiveLevel);
+		}
 	}
 
 	/**