diff --git a/src/web/public/index.html b/src/web/public/index.html
index 50daf7c7..963af0c7 100644
--- a/src/web/public/index.html
+++ b/src/web/public/index.html
@@ -1095,6 +1095,17 @@
               </label>
               <span class="form-hint">Use 1M token context window (model: opus[1m]) for all new sessions</span>
             </div>
+            <div class="form-row">
+              <label>Thinking Effort</label>
+              <select id="appSettingsThinkingEffort" class="form-select">
+                <option value="">Default</option>
+                <option value="low">Low</option>
+                <option value="medium">Medium</option>
+                <option value="high">High</option>
+                <option value="max">Max</option>
+              </select>
+              <span class="form-hint">Set CLAUDE_CODE_EFFORT_LEVEL for all new sessions (default = no override)</span>
+            </div>
             <!-- Nice Priority Section -->
             <div class="form-section-header">Nice Priority</div>
             <div class="form-row form-row-switch">
diff --git a/src/web/public/session-ui.js b/src/web/public/session-ui.js
index 86fccf80..dc1e79b1 100644
--- a/src/web/public/session-ui.js
+++ b/src/web/public/session-ui.js
@@ -323,6 +323,10 @@ Object.assign(CodemanApp.prototype, {
       if (caseSettings.agentTeams || globalSettings.agentTeamsEnabled) {
         envOverrides.CLAUDE_CODE_EXPERIMENTAL_AGENT_TEAMS = '1';
       }
+      const thinkingEffort = globalSettings.thinkingEffort;
+      if (thinkingEffort) {
+        envOverrides.CLAUDE_CODE_EFFORT_LEVEL = thinkingEffort;
+      }
       const hasEnvOverrides = Object.keys(envOverrides).length > 0;
       const useOpus1m = caseSettings.opusContext1m || globalSettings.opusContext1mEnabled;
       const modelOverride = useOpus1m ? 'opus[1m]' : '';
diff --git a/src/web/public/settings-ui.js b/src/web/public/settings-ui.js
index 3ee0ab24..a29a52be 100644
--- a/src/web/public/settings-ui.js
+++ b/src/web/public/settings-ui.js
@@ -334,6 +334,7 @@ Object.assign(CodemanApp.prototype, {
     // Claude Permissions settings
     document.getElementById('appSettingsAgentTeams').checked = settings.agentTeamsEnabled ?? false;
     document.getElementById('appSettingsOpusContext1m').checked = settings.opusContext1mEnabled ?? false;
+    document.getElementById('appSettingsThinkingEffort').value = settings.thinkingEffort ?? '';
     // CPU Priority settings
     const niceSettings = settings.nice || {};
     document.getElementById('appSettingsNiceEnabled').checked = niceSettings.enabled ?? false;
@@ -1134,6 +1135,7 @@ Object.assign(CodemanApp.prototype, {
       // Claude Permissions settings
       agentTeamsEnabled: document.getElementById('appSettingsAgentTeams').checked,
       opusContext1mEnabled: document.getElementById('appSettingsOpusContext1m').checked,
+      thinkingEffort: document.getElementById('appSettingsThinkingEffort').value,
       // CPU Priority settings
       nice: {
         enabled: document.getElementById('appSettingsNiceEnabled').checked,