diff --git a/src/cli/App.tsx b/src/cli/App.tsx
index 4907ed0..4054450 100644
--- a/src/cli/App.tsx
+++ b/src/cli/App.tsx
@@ -1737,7 +1737,11 @@ export default function App({
         // If we're sending a new message, old pending state is no longer relevant
         // Pass false to avoid setting interrupted=true, which causes race conditions
         // with concurrent processConversation calls reading the flag
-        markIncompleteToolsAsCancelled(buffersRef.current, false);
+        markIncompleteToolsAsCancelled(
+          buffersRef.current,
+          false,
+          "internal_cancel",
+        );
         // Reset interrupted flag since we're starting a fresh stream
         buffersRef.current.interrupted = false;
 
@@ -2169,7 +2173,11 @@ export default function App({
               abortControllerRef.current?.signal.aborted
             ) {
               setStreaming(false);
-              markIncompleteToolsAsCancelled(buffersRef.current);
+              markIncompleteToolsAsCancelled(
+                buffersRef.current,
+                true,
+                "user_interrupt",
+              );
               refreshDerived();
               return;
             }
@@ -2422,7 +2430,11 @@ export default function App({
                     queueApprovalResults(allResults, autoAllowedMetadata);
                   }
                   setStreaming(false);
-                  markIncompleteToolsAsCancelled(buffersRef.current);
+                  markIncompleteToolsAsCancelled(
+                    buffersRef.current,
+                    true,
+                    "user_interrupt",
+                  );
                   refreshDerived();
                   return;
                 }
@@ -2540,7 +2552,11 @@ export default function App({
               abortControllerRef.current?.signal.aborted
             ) {
               setStreaming(false);
-              markIncompleteToolsAsCancelled(buffersRef.current);
+              markIncompleteToolsAsCancelled(
+                buffersRef.current,
+                true,
+                "user_interrupt",
+              );
               refreshDerived();
               return;
             }
@@ -2762,7 +2778,11 @@ export default function App({
           llmApiErrorRetriesRef.current = 0;
 
           // Mark incomplete tool calls as finished to prevent stuck blinking UI
-          markIncompleteToolsAsCancelled(buffersRef.current);
+          markIncompleteToolsAsCancelled(
+            buffersRef.current,
+            true,
+            "stream_error",
+          );
 
           // Track the error in telemetry
           telemetry.trackError(
@@ -2847,7 +2867,11 @@ export default function App({
         }
       } catch (e) {
         // Mark incomplete tool calls as cancelled to prevent stuck blinking UI
-        markIncompleteToolsAsCancelled(buffersRef.current);
+        markIncompleteToolsAsCancelled(
+          buffersRef.current,
+          true,
+          e instanceof APIUserAbortError ? "user_interrupt" : "stream_error",
+        );
 
         // If using eager cancel and this is an abort error, silently ignore it
         // The user already got "Stream interrupted by user" feedback from handleInterrupt
@@ -2979,7 +3003,11 @@ export default function App({
       // ALSO abort the main stream - don't leave it running
       buffersRef.current.abortGeneration =
         (buffersRef.current.abortGeneration || 0) + 1;
-      const toolsCancelled = markIncompleteToolsAsCancelled(buffersRef.current);
+      const toolsCancelled = markIncompleteToolsAsCancelled(
+        buffersRef.current,
+        true,
+        "user_interrupt",
+      );
 
       // Mark any running subagents as interrupted
       interruptActiveSubagents(INTERRUPTED_BY_USER);
@@ -3029,7 +3057,11 @@ export default function App({
       // This ensures onChunk and other guards see interrupted=true immediately.
       buffersRef.current.abortGeneration =
         (buffersRef.current.abortGeneration || 0) + 1;
-      const toolsCancelled = markIncompleteToolsAsCancelled(buffersRef.current);
+      const toolsCancelled = markIncompleteToolsAsCancelled(
+        buffersRef.current,
+        true,
+        "user_interrupt",
+      );
 
       // Mark any running subagents as interrupted
       interruptActiveSubagents(INTERRUPTED_BY_USER);
@@ -5931,7 +5963,11 @@ DO NOT respond to these messages or otherwise consider them in your response unl
                     queueApprovalResults(queuedResults, autoAllowedMetadata);
                   }
                   setStreaming(false);
-                  markIncompleteToolsAsCancelled(buffersRef.current);
+                  markIncompleteToolsAsCancelled(
+                    buffersRef.current,
+                    true,
+                    "user_interrupt",
+                  );
                   refreshDerived();
                   return { submitted: false };
                 }
@@ -6174,7 +6210,11 @@ DO NOT respond to these messages or otherwise consider them in your response unl
                     queueApprovalResults(queuedResults, autoAllowedMetadata);
                   }
                   setStreaming(false);
-                  markIncompleteToolsAsCancelled(buffersRef.current);
+                  markIncompleteToolsAsCancelled(
+                    buffersRef.current,
+                    true,
+                    "user_interrupt",
+                  );
                   refreshDerived();
                   return { submitted: false };
                 }
@@ -6783,7 +6823,7 @@ DO NOT respond to these messages or otherwise consider them in your response unl
     queueApprovalResults(denialResults);
 
     // Mark the pending approval tool calls as cancelled in the buffers
-    markIncompleteToolsAsCancelled(buffersRef.current);
+    markIncompleteToolsAsCancelled(buffersRef.current, true, "approval_cancel");
     refreshDerived();
 
     // Clear all approval state
@@ -7340,7 +7380,11 @@ DO NOT respond to these messages or otherwise consider them in your response unl
         queueApprovalResults(denialResults);
 
         // Mark tool as cancelled in buffers
-        markIncompleteToolsAsCancelled(buffersRef.current);
+        markIncompleteToolsAsCancelled(
+          buffersRef.current,
+          true,
+          "internal_cancel",
+        );
         refreshDerived();
 
         // Clear all approval state (same as handleCancelApprovals)
diff --git a/src/cli/helpers/accumulator.ts b/src/cli/helpers/accumulator.ts
index bf3153f..c78338e 100644
--- a/src/cli/helpers/accumulator.ts
+++ b/src/cli/helpers/accumulator.ts
@@ -272,9 +272,23 @@ export function markCurrentLineAsFinished(b: Buffers) {
  *   with concurrent processConversation calls reading the flag.
  * @returns true if any tool calls were marked as cancelled
  */
+export type CancelReason =
+  | "user_interrupt"
+  | "stream_error"
+  | "internal_cancel"
+  | "approval_cancel";
+
+const CANCEL_REASON_TEXT: Record<CancelReason, string> = {
+  user_interrupt: INTERRUPTED_BY_USER,
+  stream_error: "Stream error",
+  internal_cancel: "Cancelled",
+  approval_cancel: "Approval cancelled",
+};
+
 export function markIncompleteToolsAsCancelled(
   b: Buffers,
   setInterruptedFlag = true,
+  reason: CancelReason = "internal_cancel",
 ): boolean {
   // Mark buffer as interrupted to skip stale throttled refreshes
   // (only when actually interrupting, not when clearing stale state at startup)
@@ -289,7 +303,7 @@ export function markIncompleteToolsAsCancelled(
         ...line,
         phase: "finished" as const,
         resultOk: false,
-        resultText: INTERRUPTED_BY_USER,
+        resultText: CANCEL_REASON_TEXT[reason],
       };
       b.byId.set(id, updatedLine);
       anyToolsCancelled = true;
diff --git a/src/cli/helpers/stream.ts b/src/cli/helpers/stream.ts
index a9719a6..e0498f1 100644
--- a/src/cli/helpers/stream.ts
+++ b/src/cli/helpers/stream.ts
@@ -101,7 +101,7 @@ export async function drainStream(
       // Check if stream was aborted
       if (abortSignal?.aborted) {
         stopReason = "cancelled";
-        markIncompleteToolsAsCancelled(buffers);
+        markIncompleteToolsAsCancelled(buffers, true, "user_interrupt");
         queueMicrotask(refresh);
         break;
       }
@@ -135,7 +135,7 @@ export async function drainStream(
       // Check abort signal before processing - don't add data after interrupt
       if (abortSignal?.aborted) {
         stopReason = "cancelled";
-        markIncompleteToolsAsCancelled(buffers);
+        markIncompleteToolsAsCancelled(buffers, true, "user_interrupt");
         queueMicrotask(refresh);
         break;
       }
@@ -172,7 +172,7 @@ export async function drainStream(
 
     // Set error stop reason so drainStreamWithResume can try to reconnect
     stopReason = "error";
-    markIncompleteToolsAsCancelled(buffers);
+    markIncompleteToolsAsCancelled(buffers, true, "stream_error");
     queueMicrotask(refresh);
   } finally {
     // Clean up abort listener
@@ -189,7 +189,7 @@ export async function drainStream(
   // (SDK returns gracefully on abort), mark as cancelled
   if (abortedViaListener && !stopReason) {
     stopReason = "cancelled";
-    markIncompleteToolsAsCancelled(buffers);
+    markIncompleteToolsAsCancelled(buffers, true, "user_interrupt");
     queueMicrotask(refresh);
   }
 
@@ -200,7 +200,7 @@ export async function drainStream(
 
   // Mark incomplete tool calls as cancelled if stream was cancelled
   if (stopReason === "cancelled") {
-    markIncompleteToolsAsCancelled(buffers);
+    markIncompleteToolsAsCancelled(buffers, true, "user_interrupt");
   }
 
   // Mark the final line as finished now that stream has ended
diff --git a/src/headless.ts b/src/headless.ts
index fe1a70d..1515058 100644
--- a/src/headless.ts
+++ b/src/headless.ts
@@ -1460,7 +1460,7 @@ export async function handleHeadlessCommand(
       }
 
       // Mark incomplete tool calls as cancelled to prevent stuck state
-      markIncompleteToolsAsCancelled(buffers);
+      markIncompleteToolsAsCancelled(buffers, true, "stream_error");
 
       // Extract error details from buffers if available
       const errorLines = toLines(buffers).filter(
@@ -1518,7 +1518,7 @@ export async function handleHeadlessCommand(
     }
   } catch (error) {
     // Mark incomplete tool calls as cancelled
-    markIncompleteToolsAsCancelled(buffers);
+    markIncompleteToolsAsCancelled(buffers, true, "stream_error");
 
     // Use comprehensive error formatting (same as TUI mode)
     const errorDetails = formatErrorDetails(error, agent.id);