diff --git a/packages/tui/src/routes/session/index.tsx b/packages/tui/src/routes/session/index.tsx
index 9a3456c7a9..f8d3302461 100644
--- a/packages/tui/src/routes/session/index.tsx
+++ b/packages/tui/src/routes/session/index.tsx
@@ -1092,32 +1092,28 @@ function SessionReasoningGroupView(props: {
   const renderer = useRenderer()
   const [expanded, setExpanded] = createSignal(false)
   const [hover, setHover] = createSignal(false)
-  const parts = createMemo<{ message: SessionMessageAssistant; part: SessionMessageAssistantReasoning }[]>(
-    (previous) => {
-      const next = props.refs.flatMap((ref) => {
-        const message = props.message(ref.messageID)
-        if (message?.type !== "assistant") return []
-        const part = resolvePart(message, ref.partID)
-        if (part?.type !== "reasoning" || !part.text.replace("[REDACTED]", "").trim()) return []
-        return [{ message, part }]
-      })
-      return next.length > 0 ? next : previous
-    },
-    [] as { message: SessionMessageAssistant; part: SessionMessageAssistantReasoning }[],
+  const parts = createMemo(() =>
+    props.refs.flatMap((ref) => {
+      const message = props.message(ref.messageID)
+      if (message?.type !== "assistant") return []
+      const part = resolvePart(message, ref.partID)
+      if (part?.type !== "reasoning" || !reasoningContent(part)) return []
+      return [{ message, part }]
+    }),
   )
   const latest = createMemo((previous: string | null) => {
     const item = parts().at(-1)
     if (!item) return previous
-    const title = reasoningSummary(item.part.text.replace("[REDACTED]", "").trim()).title
+    const title = reasoningSummary(reasoningContent(item.part)).title
     if (title) return title
     if (item.part.time?.completed !== undefined || item.message.time.completed !== undefined) return null
     return previous
   }, null)
   const duration = createMemo(() =>
     parts().reduce((total, item) => {
-      const end = item.part.time?.completed ?? item.message.time.completed
-      const start = item.part.time?.created ?? item.message.time.created
-      return total + (end === undefined ? 0 : Math.max(0, end - start))
+      const start = item.part.time?.created
+      const end = item.part.time?.completed
+      return total + (start === undefined || end === undefined ? 0 : Math.max(0, end - start))
     }, 0),
   )
 
@@ -1125,9 +1121,7 @@ function SessionReasoningGroupView(props: {
     <Show when={parts().length > 0}>
       <Show
         when={ctx.thinkingMode() === "hide"}
-        fallback={
-          <For each={parts()}>{(item) => <ReasoningPart part={item.part} message={item.message} last={false} />}</For>
-        }
+        fallback={<For each={props.refs}>{(ref) => <SessionPartView partRef={ref} message={props.message} />}</For>}
       >
         <box flexDirection="column" flexShrink={0}>
           <InlineToolRow
@@ -1156,27 +1150,45 @@ function SessionReasoningGroupView(props: {
           </InlineToolRow>
           <Show when={expanded()}>
             <box paddingLeft={3}>
-              <For each={parts()}>
-                {(item) => (
-                  <box marginTop={1}>
-                    <box
-                      border={["left"]}
-                      customBorderChars={SplitBorder.customBorderChars}
-                      borderColor={theme.backgroundElement}
-                      paddingLeft={1}
-                    >
-                      <code
-                        filetype="markdown"
-                        drawUnstyledText={false}
-                        streaming={false}
-                        syntaxStyle={syntax()}
-                        content={item.part.text.replace("[REDACTED]", "").trim()}
-                        conceal={ctx.markdownMode() === "rendered"}
-                        fg={theme.textMuted}
-                      />
-                    </box>
-                  </box>
-                )}
+              <For each={props.refs}>
+                {(ref) => {
+                  const message = createMemo(() => {
+                    const item = props.message(ref.messageID)
+                    return item?.type === "assistant" ? item : undefined
+                  })
+                  const part = createMemo(() => {
+                    const item = message()
+                    if (!item) return undefined
+                    const part = resolvePart(item, ref.partID)
+                    return part?.type === "reasoning" ? part : undefined
+                  })
+                  const content = createMemo(() => {
+                    const item = part()
+                    return item ? reasoningContent(item) : ""
+                  })
+                  return (
+                    <Show when={content()}>
+                      <box marginTop={1}>
+                        <box
+                          border={["left"]}
+                          customBorderChars={SplitBorder.customBorderChars}
+                          borderColor={theme.backgroundElement}
+                          paddingLeft={1}
+                        >
+                          <code
+                            filetype="markdown"
+                            drawUnstyledText={false}
+                            streaming={part()?.time?.completed === undefined && message()?.time.completed === undefined}
+                            syntaxStyle={syntax()}
+                            content={content()}
+                            conceal={ctx.markdownMode() === "rendered"}
+                            fg={theme.textMuted}
+                          />
+                        </box>
+                      </box>
+                    </Show>
+                  )
+                }}
               </For>
             </box>
           </Show>
@@ -1789,10 +1801,7 @@ function ReasoningPart(props: {
   // layout never shifts. Click to open the full markdown block, click to close.
   const [expanded, setExpanded] = createSignal(false)
 
-  const content = createMemo(() => {
-    // OpenRouter encrypts some reasoning blocks; drop the placeholder.
-    return props.part.text.replace("[REDACTED]", "").trim()
-  })
+  const content = createMemo(() => reasoningContent(props.part))
   const isDone = createMemo(
     () => props.part.time?.completed !== undefined || props.message.time.completed !== undefined,
   )
@@ -1852,6 +1861,11 @@ function ReasoningPart(props: {
   )
 }
 
+function reasoningContent(part: SessionMessageAssistantReasoning) {
+  // OpenRouter encrypts some reasoning blocks; drop the placeholder.
+  return part.text.replace("[REDACTED]", "").trim()
+}
+
 function ReasoningHeader(props: {
   toggleable: boolean
   open: boolean
diff --git a/packages/tui/src/routes/session/rows.ts b/packages/tui/src/routes/session/rows.ts
index 6d3f4cf422..3fb9323715 100644
--- a/packages/tui/src/routes/session/rows.ts
+++ b/packages/tui/src/routes/session/rows.ts
@@ -132,39 +132,11 @@ export function createSessionRows(sessionID: Accessor<string>) {
       }),
     )
 
-  const appendPart = (ref: PartRef, name?: string) =>
+  const appendPart = (ref: PartRef, part: AppendPart) =>
     setRows(
       produce((draft) => {
         if (hasPart(draft, ref)) return
-        const index = queuedStart(draft)
-        if (ref.partID.startsWith("reasoning:")) {
-          const previous = draft[index - 1]
-          if (previous?.type === "group" && previous.kind === "reasoning") {
-            previous.refs.push(ref)
-            return
-          }
-          completePrevious(draft, index)
-          draft.splice(index, 0, { type: "group", kind: "reasoning", refs: [ref], completed: false })
-          return
-        }
-        if (name && exploration(name)) {
-          const previous = draft[index - 1]
-          if (previous?.type === "group" && previous.kind === "exploration") {
-            previous.refs.push(ref)
-            return
-          }
-          completePrevious(draft, index)
-          draft.splice(index, 0, {
-            type: "group",
-            kind: "exploration",
-            refs: [ref],
-            pending: [],
-            completed: false,
-          })
-          return
-        }
-        completePrevious(draft, index)
-        draft.splice(index, 0, { type: "part", ref })
+        append(draft, ref, part, queuedStart(draft))
       }),
     )
 
@@ -230,23 +202,32 @@ export function createSessionRows(sessionID: Accessor<string>) {
     data.on("session.model.selected", message),
     data.on("session.text.delta", (event) => {
       if (event.data.sessionID === sessionID() && event.data.delta.trim())
-        appendPart({ messageID: event.data.assistantMessageID, partID: `text:${event.data.ordinal}` })
+        appendPart({ messageID: event.data.assistantMessageID, partID: `text:${event.data.ordinal}` }, { type: "text" })
     }),
     data.on("session.text.ended", (event) => {
       if (event.data.sessionID === sessionID() && event.data.text.trim())
-        appendPart({ messageID: event.data.assistantMessageID, partID: `text:${event.data.ordinal}` })
+        appendPart({ messageID: event.data.assistantMessageID, partID: `text:${event.data.ordinal}` }, { type: "text" })
     }),
     data.on("session.reasoning.delta", (event) => {
-      if (event.data.sessionID === sessionID())
-        appendPart({ messageID: event.data.assistantMessageID, partID: `reasoning:${event.data.ordinal}` })
+      if (event.data.sessionID === sessionID() && event.data.delta.trim())
+        appendPart(
+          { messageID: event.data.assistantMessageID, partID: `reasoning:${event.data.ordinal}` },
+          { type: "reasoning" },
+        )
     }),
     data.on("session.reasoning.ended", (event) => {
       if (event.data.sessionID === sessionID() && event.data.text.trim())
-        appendPart({ messageID: event.data.assistantMessageID, partID: `reasoning:${event.data.ordinal}` })
+        appendPart(
+          { messageID: event.data.assistantMessageID, partID: `reasoning:${event.data.ordinal}` },
+          { type: "reasoning" },
+        )
     }),
     data.on("session.tool.input.started", (event) => {
       if (event.data.sessionID === sessionID())
-        appendPart({ messageID: event.data.assistantMessageID, partID: event.data.callID }, event.data.name)
+        appendPart(
+          { messageID: event.data.assistantMessageID, partID: event.data.callID },
+          { type: "tool", name: event.data.name },
+        )
     }),
     data.on("session.retry.scheduled", (event) => {
       if (event.data.sessionID === sessionID()) appendFooter(event.data.assistantMessageID)
@@ -305,31 +286,31 @@ export function resolvePart(message: SessionMessageAssistant, partID: string) {
   return message.content.filter((part) => part.type === match[1])[ordinal]
 }
 
-function append(rows: SessionRow[], ref: PartRef, part: SessionMessageAssistant["content"][number]) {
+type AppendPart = { type: "text" } | { type: "reasoning" } | { type: "tool"; name: string }
+
+function append(rows: SessionRow[], ref: PartRef, part: AppendPart, index = rows.length) {
   if (part.type === "reasoning") {
-    const previous = rows.at(-1)
+    const previous = rows[index - 1]
     if (previous?.type === "group" && previous.kind === "reasoning") {
       previous.refs.push(ref)
       return
     }
-    completePrevious(rows)
-    rows.push({ type: "group", kind: "reasoning", refs: [ref], completed: false })
+    completePrevious(rows, index)
+    rows.splice(index, 0, { type: "group", kind: "reasoning", refs: [ref], completed: false })
     return
   }
-  if (part.type === "tool") {
-    if (exploration(part.name)) {
-      const previous = rows.at(-1)
-      if (previous?.type === "group" && previous.kind === "exploration") {
-        previous.refs.push(ref)
-        return
-      }
-      completePrevious(rows)
-      rows.push({ type: "group", kind: "exploration", refs: [ref], pending: [], completed: false })
+  if (part.type === "tool" && exploration(part.name)) {
+    const previous = rows[index - 1]
+    if (previous?.type === "group" && previous.kind === "exploration") {
+      previous.refs.push(ref)
       return
     }
+    completePrevious(rows, index)
+    rows.splice(index, 0, { type: "group", kind: "exploration", refs: [ref], pending: [], completed: false })
+    return
   }
-  completePrevious(rows)
-  rows.push({ type: "part", ref })
+  completePrevious(rows, index)
+  rows.splice(index, 0, { type: "part", ref })
 }
 
 function completePrevious(rows: SessionRow[], index = rows.length) {
diff --git a/packages/tui/test/cli/tui/data.test.tsx b/packages/tui/test/cli/tui/data.test.tsx
index 493c290325..ae1eabf683 100644
--- a/packages/tui/test/cli/tui/data.test.tsx
+++ b/packages/tui/test/cli/tui/data.test.tsx
@@ -737,6 +737,52 @@ test("completes exploration when a queued prompt is promoted", async () => {
   }
 })
 
+test("classifies live tool rows independently of their call ID", async () => {
+  const events = createEventStream()
+  const sessionID = "session-tool-call-id"
+  const calls = createFetch((url) => {
+    if (url.pathname === `/api/session/${sessionID}/message`) return json({ data: [], cursor: {} })
+  }, events)
+  let rows!: ReturnType<typeof createSessionRows>
+
+  function Probe() {
+    rows = createSessionRows(() => sessionID)
+    return <box />
+  }
+
+  const app = await testRender(() => (
+    <TestTuiContexts>
+      <ClientProvider api={createApi(calls.fetch)}>
+        <ProjectProvider>
+          <DataProvider>
+            <Probe />
+          </DataProvider>
+        </ProjectProvider>
+      </ClientProvider>
+    </TestTuiContexts>
+  ))
+
+  try {
+    emitEvent(events, {
+      id: "evt_tool_started",
+      created: 1,
+      type: "session.tool.input.started",
+      durable: durable(sessionID),
+      data: {
+        sessionID,
+        assistantMessageID: "message-assistant",
+        callID: "reasoning:0",
+        name: "bash",
+      },
+    })
+
+    await wait(() => rows.length > 0)
+    expect(rows).toEqual([{ type: "part", ref: { messageID: "message-assistant", partID: "reasoning:0" } }])
+  } finally {
+    app.renderer.destroy()
+  }
+})
+
 test("removes committed revert messages from local state", async () => {
   const events = createEventStream()
   const sessionID = "session-revert"
diff --git a/packages/tui/test/cli/tui/session-rows.test.ts b/packages/tui/test/cli/tui/session-rows.test.ts
index b0f2f64fbc..e158a377b0 100644
--- a/packages/tui/test/cli/tui/session-rows.test.ts
+++ b/packages/tui/test/cli/tui/session-rows.test.ts
@@ -38,7 +38,7 @@ test("keeps non-exploration tools as individual part rows", () => {
   const messages: SessionMessageInfo[] = [
     assistant("assistant-1", [
       { type: "tool", id: "read-1", name: "read", state: pending(), time: { created: 1 } },
-      { type: "tool", id: "bash-1", name: "bash", state: pending(), time: { created: 2 } },
+      { type: "tool", id: "reasoning:0", name: "bash", state: pending(), time: { created: 2 } },
       { type: "tool", id: "grep-1", name: "grep", state: pending(), time: { created: 3 } },
     ]),
   ]
@@ -51,7 +51,7 @@ test("keeps non-exploration tools as individual part rows", () => {
       completed: true,
       refs: [{ messageID: "assistant-1", partID: "read-1" }],
     },
-    { type: "part", ref: { messageID: "assistant-1", partID: "bash-1" } },
+    { type: "part", ref: { messageID: "assistant-1", partID: "reasoning:0" } },
     {
       type: "group",
       kind: "exploration",