diff --git a/docs/agent-skill-sharing-implementation-checklist.md b/docs/agent-skill-sharing-implementation-checklist.md
index 0dbf8bf001b..fc7095519cc 100644
--- a/docs/agent-skill-sharing-implementation-checklist.md
+++ b/docs/agent-skill-sharing-implementation-checklist.md
@@ -1011,8 +1011,9 @@ does not mean the surrounding phase is complete.
 - [ ] Test connection loss and resumption or restart behavior at every transfer boundary. Lost
       final install-response convergence is covered for direct and staged paired-runtime paths;
       deterministic cancellation now settles in-flight and queued paired calls across every
-      transport without leaking request admission or disrupting peers. Restart and the remaining
-      physical disconnect boundaries are still open.
+      transport without leaking request admission or disrupting peers. Client-mediated transfer
+      also cancels and cleans a fully uploaded session when cancellation interrupts the commit RPC.
+      Restart and the remaining physical disconnect boundaries are still open.
 
 ### Mixed versions
 
diff --git a/src/main/skills/skill-client-mediated-transfer-cancellation.test.ts b/src/main/skills/skill-client-mediated-transfer-cancellation.test.ts
new file mode 100644
index 00000000000..ea95d143f2c
--- /dev/null
+++ b/src/main/skills/skill-client-mediated-transfer-cancellation.test.ts
@@ -0,0 +1,113 @@
+import { mkdtemp, rm, writeFile } from 'node:fs/promises'
+import { tmpdir } from 'node:os'
+import { join } from 'node:path'
+import { afterEach, beforeEach, describe, expect, it, vi } from 'vitest'
+
+const mocks = vi.hoisted(() => ({
+  callRuntimeEnvironment: vi.fn(),
+  downloadSkillPackageGrant: vi.fn()
+}))
+
+vi.mock('../ipc/runtime-environment-transport-routing', () => ({
+  callRuntimeEnvironment: mocks.callRuntimeEnvironment
+}))
+vi.mock('./skill-package-download', () => ({
+  downloadSkillPackageGrant: mocks.downloadSkillPackageGrant
+}))
+
+import { transferSkillPackageToRuntime } from './skill-client-mediated-transfer'
+
+describe('transferSkillPackageToRuntime cancellation', () => {
+  let root = ''
+
+  beforeEach(async () => {
+    root = await mkdtemp(join(tmpdir(), 'orca-skill-transfer-cancel-test-'))
+    mocks.callRuntimeEnvironment.mockReset()
+    mocks.downloadSkillPackageGrant.mockReset()
+  })
+
+  afterEach(async () => {
+    await rm(root, { recursive: true, force: true })
+  })
+
+  it('cancels a committed chunk session when the commit request is interrupted', async () => {
+    const bytes = Buffer.from('package-data')
+    const archivePath = join(root, 'package.tar.gz')
+    await writeFile(archivePath, bytes)
+    const downloadCleanup = vi.fn(async () => undefined)
+    const controller = new AbortController()
+    let commitStarted: () => void = () => {}
+    const commitPending = new Promise<void>((resolve) => {
+      commitStarted = resolve
+    })
+    mocks.downloadSkillPackageGrant.mockResolvedValue({ archivePath, cleanup: downloadCleanup })
+    mocks.callRuntimeEnvironment.mockImplementation((...args: unknown[]) => {
+      const method = args[2]
+      if (method === 'skills.beginUpload') {
+        return Promise.resolve({
+          id: 'rpc-begin',
+          ok: true,
+          result: { uploadId: 'upload-1', chunkBytes: 256 * 1024 },
+          _meta: { runtimeId: 'runtime-1' }
+        })
+      }
+      if (method === 'skills.uploadChunk') {
+        return Promise.resolve({
+          id: 'rpc-chunk',
+          ok: true,
+          result: { acknowledgedOffset: bytes.length },
+          _meta: { runtimeId: 'runtime-1' }
+        })
+      }
+      if (method === 'skills.commitUpload') {
+        const options = args[7] as { signal?: AbortSignal }
+        return new Promise((_resolve, reject) => {
+          options.signal?.addEventListener('abort', () => reject(options.signal?.reason), {
+            once: true
+          })
+          commitStarted()
+        })
+      }
+      return Promise.resolve({
+        id: 'rpc-cancel',
+        ok: true,
+        result: undefined,
+        _meta: { runtimeId: 'runtime-1' }
+      })
+    })
+
+    const pending = transferSkillPackageToRuntime({
+      userDataPath: root,
+      environmentId: 'environment-1',
+      transferId: 'operation-1',
+      package: {
+        packageId: 'package-1',
+        versionId: 'version-1',
+        packageDigest: 'a'.repeat(64),
+        archiveSha256: 'b'.repeat(64),
+        compressedBytes: bytes.length
+      },
+      grant: {
+        url: 'https://storage.googleapis.com/bucket/package.tar.gz',
+        expiresAt: '2099-01-01T00:00:00.000Z'
+      },
+      requireHttps: true,
+      signal: controller.signal
+    })
+    await commitPending
+
+    controller.abort()
+    await expect(pending).rejects.toThrow('skill-install-cancelled')
+    expect(downloadCleanup).toHaveBeenCalledOnce()
+    expect(
+      mocks.callRuntimeEnvironment.mock.calls.filter((call) => call[2] === 'skills.commitUpload')
+    ).toHaveLength(1)
+    expect(mocks.callRuntimeEnvironment).toHaveBeenCalledWith(
+      root,
+      'environment-1',
+      'skills.cancelUpload',
+      { uploadId: 'upload-1' },
+      15_000
+    )
+  })
+})