diff --git a/ui-tui/src/__tests__/createGatewayEventHandler.test.ts b/ui-tui/src/__tests__/createGatewayEventHandler.test.ts
index 991c87a1c6..658ca571b6 100644
--- a/ui-tui/src/__tests__/createGatewayEventHandler.test.ts
+++ b/ui-tui/src/__tests__/createGatewayEventHandler.test.ts
@@ -123,6 +123,20 @@ describe('createGatewayEventHandler', () => {
     expect(appended[0]?.toolTokens).toBeGreaterThan(0)
   })
 
+  it('streams legacy thinking.delta into visible reasoning state', () => {
+    vi.useFakeTimers()
+    const appended: Msg[] = []
+    const streamed = 'short streamed reasoning'
+
+    createGatewayEventHandler(buildCtx(appended))({ payload: { text: streamed }, type: 'thinking.delta' } as any)
+    vi.runOnlyPendingTimers()
+
+    expect(getTurnState().reasoning).toBe(streamed)
+    expect(getTurnState().reasoningActive).toBe(true)
+    expect(getTurnState().reasoningTokens).toBe(estimateTokensRough(streamed))
+    vi.useRealTimers()
+  })
+
   it('ignores fallback reasoning.available when streamed reasoning already exists', () => {
     const appended: Msg[] = []
     const streamed = 'short streamed reasoning'
diff --git a/ui-tui/src/app/createGatewayEventHandler.ts b/ui-tui/src/app/createGatewayEventHandler.ts
index 15cf00a5a9..94e82c56c3 100644
--- a/ui-tui/src/app/createGatewayEventHandler.ts
+++ b/ui-tui/src/app/createGatewayEventHandler.ts
@@ -220,7 +220,12 @@ export function createGatewayEventHandler(ctx: GatewayEventHandlerContext): (ev:
         const text = ev.payload?.text
 
         if (text !== undefined) {
-          scheduleThinkingStatus(text ? String(text) : statusFromBusy())
+          const value = String(text)
+          scheduleThinkingStatus(value || statusFromBusy())
+
+          if (value) {
+            turnController.recordReasoningDelta(value)
+          }
         }
 
         return