diff --git a/src-tauri/src/config.rs b/src-tauri/src/config.rs
index eb52ab1..6a21c23 100644
--- a/src-tauri/src/config.rs
+++ b/src-tauri/src/config.rs
@@ -28,6 +28,9 @@ pub struct ClaudeStartOptions {
 
     #[serde(default)]
     pub use_worktree: bool,
+
+    #[serde(default)]
+    pub disable_1m_context: bool,
 }
 
 #[derive(Debug, Clone, Serialize, Deserialize)]
@@ -119,6 +122,9 @@ pub struct HikariConfig {
 
     #[serde(default)]
     pub use_worktree: bool,
+
+    #[serde(default)]
+    pub disable_1m_context: bool,
 }
 
 impl Default for HikariConfig {
@@ -152,6 +158,7 @@ impl Default for HikariConfig {
             budget_warning_threshold: 0.8,
             discord_rpc_enabled: true,
             use_worktree: false,
+            disable_1m_context: false,
         }
     }
 }
@@ -259,6 +266,8 @@ mod tests {
         assert_eq!(config.budget_action, BudgetAction::Warn);
         assert!((config.budget_warning_threshold - 0.8).abs() < f32::EPSILON);
         assert!(config.discord_rpc_enabled);
+        assert!(!config.use_worktree);
+        assert!(!config.disable_1m_context);
     }
 
     #[test]
@@ -292,6 +301,7 @@ mod tests {
             budget_warning_threshold: 0.75,
             discord_rpc_enabled: true,
             use_worktree: true,
+            disable_1m_context: false,
         };
 
         let json = serde_json::to_string(&config).unwrap();
diff --git a/src-tauri/src/wsl_bridge.rs b/src-tauri/src/wsl_bridge.rs
index c3e5fc8..77119c6 100644
--- a/src-tauri/src/wsl_bridge.rs
+++ b/src-tauri/src/wsl_bridge.rs
@@ -279,6 +279,11 @@ impl WslBridge {
                 }
             }
 
+            // Disable 1M context window if requested
+            if options.disable_1m_context {
+                cmd.env("CLAUDE_CODE_DISABLE_1M_CONTEXT", "1");
+            }
+
             cmd
         } else {
             // Running on Windows - use wsl with bash login shell to ensure PATH is loaded
@@ -319,6 +324,11 @@ impl WslBridge {
                 }
             }
 
+            // Disable 1M context window if requested
+            if options.disable_1m_context {
+                claude_cmd.push_str("CLAUDE_CODE_DISABLE_1M_CONTEXT=1 ");
+            }
+
             claude_cmd.push_str(
                 "claude --output-format stream-json --input-format stream-json --verbose",
             );
diff --git a/src/lib/commands/slashCommands.ts b/src/lib/commands/slashCommands.ts
index cdcfdd7..8d252c8 100644
--- a/src/lib/commands/slashCommands.ts
+++ b/src/lib/commands/slashCommands.ts
@@ -62,6 +62,7 @@ async function changeDirectory(path: string): Promise<void> {
         mcp_servers_json: config.mcp_servers_json || null,
         allowed_tools: allAllowedTools,
         use_worktree: config.use_worktree ?? false,
+        disable_1m_context: config.disable_1m_context ?? false,
       },
     });
 
@@ -137,6 +138,7 @@ async function startNewConversation(): Promise<void> {
         mcp_servers_json: config.mcp_servers_json || null,
         allowed_tools: allAllowedTools,
         use_worktree: config.use_worktree ?? false,
+        disable_1m_context: config.disable_1m_context ?? false,
       },
     });
 
diff --git a/src/lib/components/ConfigSidebar.svelte b/src/lib/components/ConfigSidebar.svelte
index 4c82802..c4905f0 100644
--- a/src/lib/components/ConfigSidebar.svelte
+++ b/src/lib/components/ConfigSidebar.svelte
@@ -54,6 +54,7 @@
     discord_rpc_enabled: true,
     show_thinking_blocks: true,
     use_worktree: false,
+    disable_1m_context: false,
   });
 
   let showCustomThemeEditor = $state(false);
@@ -489,6 +490,22 @@
           Launch sessions with <code class="font-mono">--worktree</code> for isolated git worktree environments
         </p>
       </div>
+
+      <!-- Disable 1M Context Window -->
+      <div class="mb-4">
+        <label class="flex items-center gap-3 cursor-pointer">
+          <input
+            type="checkbox"
+            bind:checked={config.disable_1m_context}
+            class="w-4 h-4 rounded border-[var(--border-color)] bg-[var(--bg-primary)] text-[var(--accent-primary)] focus:ring-[var(--accent-primary)]"
+          />
+          <span class="text-sm text-[var(--text-primary)]">Disable 1M context window</span>
+        </label>
+        <p class="text-xs text-[var(--text-tertiary)] mt-1 ml-7">
+          Sets <code class="font-mono">CLAUDE_CODE_DISABLE_1M_CONTEXT=1</code> to opt out of the extended
+          context window
+        </p>
+      </div>
     </section>
 
     <!-- Greeting Section -->
diff --git a/src/lib/components/InputBar.svelte b/src/lib/components/InputBar.svelte
index 3f9ceeb..62ea928 100644
--- a/src/lib/components/InputBar.svelte
+++ b/src/lib/components/InputBar.svelte
@@ -363,6 +363,7 @@ User: ${formattedMessage}`;
               mcp_servers_json: config.mcp_servers_json || null,
               allowed_tools: allAllowedTools,
               use_worktree: config.use_worktree ?? false,
+              disable_1m_context: config.disable_1m_context ?? false,
             },
           });
 
diff --git a/src/lib/components/PermissionModal.svelte b/src/lib/components/PermissionModal.svelte
index 02ac993..5943ff5 100644
--- a/src/lib/components/PermissionModal.svelte
+++ b/src/lib/components/PermissionModal.svelte
@@ -88,6 +88,7 @@
           mcp_servers_json: config.mcp_servers_json || null,
           allowed_tools: newGrantedTools,
           use_worktree: config.use_worktree ?? false,
+          disable_1m_context: config.disable_1m_context ?? false,
         },
       });
 
diff --git a/src/lib/components/StatusBar.svelte b/src/lib/components/StatusBar.svelte
index 45f12b5..e4099b9 100644
--- a/src/lib/components/StatusBar.svelte
+++ b/src/lib/components/StatusBar.svelte
@@ -102,6 +102,7 @@
     discord_rpc_enabled: true,
     show_thinking_blocks: true,
     use_worktree: false,
+    disable_1m_context: false,
   });
 
   let streamerModeActive = $state(false);
@@ -180,6 +181,7 @@
           mcp_servers_json: currentConfig.mcp_servers_json || null,
           allowed_tools: allAllowedTools,
           use_worktree: currentConfig.use_worktree ?? false,
+          disable_1m_context: currentConfig.disable_1m_context ?? false,
         },
       });
 
@@ -292,6 +294,7 @@
           mcp_servers_json: currentConfig.mcp_servers_json || null,
           allowed_tools: allAllowedTools,
           use_worktree: currentConfig.use_worktree ?? false,
+          disable_1m_context: currentConfig.disable_1m_context ?? false,
         },
       });
 
diff --git a/src/lib/components/UserQuestionModal.svelte b/src/lib/components/UserQuestionModal.svelte
index bda1654..f26b3da 100644
--- a/src/lib/components/UserQuestionModal.svelte
+++ b/src/lib/components/UserQuestionModal.svelte
@@ -107,6 +107,7 @@
           mcp_servers_json: config.mcp_servers_json || null,
           allowed_tools: grantedToolsList,
           use_worktree: config.use_worktree ?? false,
+          disable_1m_context: config.disable_1m_context ?? false,
         },
       });
 
diff --git a/src/lib/stores/config.test.ts b/src/lib/stores/config.test.ts
index 87b6283..883e48c 100644
--- a/src/lib/stores/config.test.ts
+++ b/src/lib/stores/config.test.ts
@@ -195,6 +195,7 @@ describe("config store", () => {
         discord_rpc_enabled: true,
         show_thinking_blocks: true,
         use_worktree: false,
+        disable_1m_context: false,
       };
 
       expect(config.model).toBe("claude-sonnet-4");
@@ -242,6 +243,7 @@ describe("config store", () => {
         discord_rpc_enabled: true,
         show_thinking_blocks: true,
         use_worktree: false,
+        disable_1m_context: false,
       };
 
       expect(config.model).toBeNull();
@@ -788,6 +790,7 @@ describe("config store", () => {
         discord_rpc_enabled: false,
         show_thinking_blocks: true,
         use_worktree: false,
+        disable_1m_context: false,
       };
 
       const mockInvokeImpl = vi.mocked(invoke);
diff --git a/src/lib/stores/config.ts b/src/lib/stores/config.ts
index 3042a8b..c4b3bcd 100644
--- a/src/lib/stores/config.ts
+++ b/src/lib/stores/config.ts
@@ -49,6 +49,8 @@ export interface HikariConfig {
   show_thinking_blocks: boolean;
   // Worktree isolation
   use_worktree: boolean;
+  // Disable 1M context window
+  disable_1m_context: boolean;
 }
 
 const defaultConfig: HikariConfig = {
@@ -90,6 +92,7 @@ const defaultConfig: HikariConfig = {
   discord_rpc_enabled: true,
   show_thinking_blocks: true,
   use_worktree: false,
+  disable_1m_context: false,
 };
 
 function createConfigStore() {