🤖 refactor: deduplicate stream cleanup code in streamManager (#892)

Deduplicate cleanup logic in `streamManager.ts`.

`cancelStreamSafely` and `cleanupStream` had identical cleanup logic
(wait for processing, calculate usage, emit stream-abort, delete from
map). Now `cancelStreamSafely` delegates to `cleanupStream`, matching
how `checkSoftCancelStream` already works.

~26 lines removed, no behavior change.

---
_Generated with `mux`_

Author: ethanndickson

src/node/services/streamManager.ts

@@ -498,37 +498,8 @@ export class StreamManager extends EventEmitter {
 
       streamInfo.abortController.abort();
 
-      // CRITICAL: Wait for processing to fully complete before cleanup
-      // This prevents race conditions where the old stream is still running
-      // while a new stream starts (e.g., old stream writing to partial.json)
-      await streamInfo.processingPromise;
-
-      // For aborts, use our tracked cumulativeUsage directly instead of AI SDK's totalUsage.
-      // cumulativeUsage is updated on each finish-step event (before tool execution),
-      // so it has accurate data even when the stream is interrupted mid-tool-call.
-      // AI SDK's totalUsage may return zeros or stale data when aborted.
-      const duration = Date.now() - streamInfo.startTime;
-      const hasCumulativeUsage = (streamInfo.cumulativeUsage.totalTokens ?? 0) > 0;
-      const usage = hasCumulativeUsage ? streamInfo.cumulativeUsage : undefined;
-
-      // For context window display, use last step's usage (inputTokens = current context size)
-      const contextUsage = streamInfo.lastStepUsage;
-      const contextProviderMetadata = streamInfo.lastStepProviderMetadata;
-
-      // Include provider metadata for accurate cost calculation
-      const providerMetadata = streamInfo.cumulativeProviderMetadata;
-
-      // Emit abort event with usage if available
-      this.emit("stream-abort", {
-        type: "stream-abort",
-        workspaceId: workspaceId as string,
-        messageId: streamInfo.messageId,
-        metadata: { usage, contextUsage, duration, providerMetadata, contextProviderMetadata },
-        abandonPartial,
-      });
-
-      // Clean up immediately
-      this.workspaceStreams.delete(workspaceId);
+      // Unlike checkSoftCancelStream, await cleanup (blocking)
+      await this.cleanupStream(workspaceId, streamInfo, abandonPartial);
     } catch (error) {
       log.error("Error during stream cancellation:", error);
       // Force cleanup even if cancellation fails
@@ -575,6 +546,9 @@ export class StreamManager extends EventEmitter {
     await streamInfo.processingPromise;
 
     // For aborts, use our tracked cumulativeUsage directly instead of AI SDK's totalUsage.
+    // cumulativeUsage is updated on each finish-step event (before tool execution),
+    // so it has accurate data even when the stream is interrupted mid-tool-call.
+    // AI SDK's totalUsage may return zeros or stale data when aborted.
     const duration = Date.now() - streamInfo.startTime;
     const hasCumulativeUsage = (streamInfo.cumulativeUsage.totalTokens ?? 0) > 0;
     const usage = hasCumulativeUsage ? streamInfo.cumulativeUsage : undefined;
@@ -1563,8 +1537,7 @@ export class StreamManager extends EventEmitter {
 
   /**
    * Stops an active stream for a workspace
-   * First call: Sets soft interrupt and emits delta event → frontend shows "Interrupting..."
-   * Second call: Hard aborts the stream immediately
+   * If soft is true, performs a soft interrupt (cancels at next block boundary)
    */
   async stopStream(
     workspaceId: string,