From 048338a31422fd057bcaefc8db6c397cf33adff1 Mon Sep 17 00:00:00 2001
From: marius-kilocode <marius@kilocode.ai>
Date: Thu, 21 May 2026 11:37:59 +0200
Subject: [PATCH] fix(vscode): clear stale diff preview loading

---
 .changeset/clear-diffs-settle.md              |  5 +++
 .../kilo-vscode/src/diff/SourceController.ts  |  8 +++--
 .../tests/unit/source-controller.test.ts      | 34 +++++++++++++++++++
 3 files changed, 45 insertions(+), 2 deletions(-)
 create mode 100644 .changeset/clear-diffs-settle.md

diff --git a/.changeset/clear-diffs-settle.md b/.changeset/clear-diffs-settle.md
new file mode 100644
index 00000000000..2db456fe67e
--- /dev/null
+++ b/.changeset/clear-diffs-settle.md
@@ -0,0 +1,5 @@
+---
+"kilo-code": patch
+---
+
+Clear Agent Manager file diff previews stuck on `Loading diff...` when the active diff source stops or changes.
diff --git a/packages/kilo-vscode/src/diff/SourceController.ts b/packages/kilo-vscode/src/diff/SourceController.ts
index 47d1a771471..11a51ed3449 100644
--- a/packages/kilo-vscode/src/diff/SourceController.ts
+++ b/packages/kilo-vscode/src/diff/SourceController.ts
@@ -181,8 +181,12 @@ export class SourceController {
       return
     }
     const diff = await source.fetchFile(file).catch(() => null)
-    // Drop the response if the source has been disposed/swapped while we waited.
-    if (this.epoch !== epoch) return
+    // Discard stale content after disposal/swap, but still complete the request
+    // so consumers can clear per-file loading state.
+    if (this.epoch !== epoch) {
+      this.send(this.messages.diffFile(source, file, null))
+      return
+    }
     this.send(this.messages.diffFile(source, file, diff))
   }
 
diff --git a/packages/kilo-vscode/tests/unit/source-controller.test.ts b/packages/kilo-vscode/tests/unit/source-controller.test.ts
index f9a49cd2cbc..549fe75af02 100644
--- a/packages/kilo-vscode/tests/unit/source-controller.test.ts
+++ b/packages/kilo-vscode/tests/unit/source-controller.test.ts
@@ -345,6 +345,40 @@ describe("SourceController.requestFile", () => {
 
     controller.stop()
   })
+
+  it("posts null when a pending fetchFile result is invalidated by stop", async () => {
+    let release: () => void = () => {}
+    const workspace: DiffSource = {
+      descriptor: WORKSPACE_DESC,
+      async fetch() {
+        return { diffs: [] }
+      },
+      async fetchFile() {
+        await new Promise<void>((resolve) => (release = resolve))
+        return {
+          file: "foo.ts",
+          before: "a",
+          after: "b",
+          additions: 1,
+          deletions: 1,
+        }
+      },
+    }
+    const { controller, posted } = make({ workspace })
+
+    controller.setContext({ workspaceRoot: "/repo" })
+    await controller.activate("workspace")
+    posted.length = 0
+    const request = controller.requestFile("foo.ts")
+    controller.stop()
+    release()
+    await request
+
+    const files = byType(posted, "diffViewer.diffFile")
+    expect(files).toHaveLength(1)
+    expect(files[0]!.file).toBe("foo.ts")
+    expect(files[0]!.diff).toBeNull()
+  })
 })
 
 describe("SourceController.reactivate", () => {