diff --git a/src/main/skills/skill-upload-session-service.test.ts b/src/main/skills/skill-upload-session-service.test.ts
index 344dcc5ea4a..c12065e473c 100644
--- a/src/main/skills/skill-upload-session-service.test.ts
+++ b/src/main/skills/skill-upload-session-service.test.ts
@@ -2,7 +2,7 @@ import { createHash } from 'node:crypto'
 import { mkdir, mkdtemp, readFile, readdir, rm, stat, writeFile } from 'node:fs/promises'
 import { tmpdir } from 'node:os'
 import { join } from 'node:path'
-import { afterEach, describe, expect, it } from 'vitest'
+import { afterEach, describe, expect, it, vi } from 'vitest'
 import { SkillUploadSessionService } from './skill-upload-session-service'
 
 const roots: string[] = []
@@ -70,6 +70,45 @@ describe('SkillUploadSessionService', () => {
     await expect(readFile(staged.archivePath)).rejects.toThrow()
   })
 
+  it('removes an abandoned upload when its idle lifetime expires', async () => {
+    const root = await mkdtemp(join(tmpdir(), 'orca-skill-upload-session-'))
+    roots.push(root)
+    const uploads = join(root, 'uploads')
+    const service = new SkillUploadSessionService(uploads, { idleMs: 20 })
+    const begun = await service.begin({ package: identity(Buffer.from('abandoned')) })
+    await service.append({ uploadId: begun.uploadId, offset: 0, bytesBase64: 'YQ==' })
+
+    await vi.waitFor(async () => expect(await readdir(uploads)).toEqual([]))
+    await expect(
+      service.append({ uploadId: begun.uploadId, offset: 1, bytesBase64: 'Yg==' })
+    ).rejects.toThrow('skill-upload-session-unavailable')
+  })
+
+  it('keeps a taken archive until its new owner cleans it', async () => {
+    const root = await mkdtemp(join(tmpdir(), 'orca-skill-upload-session-'))
+    roots.push(root)
+    const service = new SkillUploadSessionService(join(root, 'uploads'), { idleMs: 20 })
+    const bytes = Buffer.from('owned package')
+    const packageIdentity = identity(bytes)
+    const begun = await service.begin({ package: packageIdentity })
+    await service.append({
+      uploadId: begun.uploadId,
+      offset: 0,
+      bytesBase64: bytes.toString('base64')
+    })
+    await service.commit(begun.uploadId)
+    const staged = await service.take(begun.uploadId, packageIdentity)
+
+    await new Promise((resolve) => setTimeout(resolve, 40))
+    await expect(readFile(staged.archivePath)).resolves.toEqual(bytes)
+    await expect(service.take(begun.uploadId, packageIdentity)).rejects.toThrow(
+      'skill-upload-session-unavailable'
+    )
+    await staged.cleanup()
+    await staged.cleanup()
+    await expect(readFile(staged.archivePath)).rejects.toThrow()
+  })
+
   it('rejects gaps, changed retries, and an archive hash mismatch', async () => {
     const root = await mkdtemp(join(tmpdir(), 'orca-skill-upload-session-'))
     roots.push(root)
diff --git a/src/main/skills/skill-upload-session-service.ts b/src/main/skills/skill-upload-session-service.ts
index 4c9dc690bb1..c82215064ac 100644
--- a/src/main/skills/skill-upload-session-service.ts
+++ b/src/main/skills/skill-upload-session-service.ts
@@ -17,6 +17,7 @@ type UploadSession = {
   path: string
   package: SkillUploadBeginRequest['package']
   handle: FileHandle | null
+  idleTimer: ReturnType<typeof setTimeout> | null
   bytesReceived: number
   touchedAt: number
   committed: boolean
@@ -25,8 +26,14 @@ type UploadSession = {
 export class SkillUploadSessionService {
   private readonly sessions = new Map<string, UploadSession>()
   private initialized: Promise<void> | null = null
+  private readonly idleMs: number
 
-  constructor(private readonly root: string) {}
+  constructor(
+    private readonly root: string,
+    options: { idleMs?: number } = {}
+  ) {
+    this.idleMs = options.idleMs ?? SESSION_IDLE_MS
+  }
 
   async begin(request: SkillUploadBeginRequest): Promise<{ uploadId: string; chunkBytes: number }> {
     await this.initialize()
@@ -37,20 +44,23 @@ export class SkillUploadSessionService {
     const id = randomUUID()
     const path = join(this.root, `${id}.tar.gz`)
     const handle = await open(path, 'wx+', 0o600)
-    this.sessions.set(id, {
+    const session: UploadSession = {
       id,
       path,
       package: request.package,
       handle,
+      idleTimer: null,
       bytesReceived: 0,
       touchedAt: Date.now(),
       committed: false
-    })
+    }
+    this.sessions.set(id, session)
+    this.touch(session)
     return { uploadId: id, chunkBytes: SKILL_UPLOAD_CHUNK_MAX_BYTES }
   }
 
   async append(request: SkillUploadChunkRequest): Promise<{ acknowledgedOffset: number }> {
-    const session = this.requireActive(request.uploadId)
+    const session = await this.requireActive(request.uploadId)
     const bytes = Buffer.from(request.bytesBase64, 'base64')
     if (
       bytes.length === 0 ||
@@ -71,7 +81,7 @@ export class SkillUploadSessionService {
       if (read.bytesRead !== bytes.length || !existing.equals(bytes)) {
         throw new Error('skill-upload-retry-mismatch')
       }
-      session.touchedAt = Date.now()
+      this.touch(session)
       return { acknowledgedOffset: session.bytesReceived }
     }
     if (session.bytesReceived + bytes.length > session.package.compressedBytes) {
@@ -82,17 +92,21 @@ export class SkillUploadSessionService {
       throw new Error('skill-upload-write-incomplete')
     }
     session.bytesReceived += bytes.length
-    session.touchedAt = Date.now()
+    this.touch(session)
     return { acknowledgedOffset: session.bytesReceived }
   }
 
   async commit(uploadId: string): Promise<{ uploadId: string }> {
     const session = this.sessions.get(uploadId)
-    if (!session || Date.now() - session.touchedAt > SESSION_IDLE_MS) {
+    if (!session) {
+      throw new Error('skill-upload-session-unavailable')
+    }
+    if (this.expired(session)) {
+      await this.cancel(uploadId)
       throw new Error('skill-upload-session-unavailable')
     }
     if (session.committed) {
-      session.touchedAt = Date.now()
+      this.touch(session)
       return { uploadId }
     }
     if (session.bytesReceived !== session.package.compressedBytes || !session.handle) {
@@ -107,7 +121,7 @@ export class SkillUploadSessionService {
       throw new Error('skill-upload-archive-hash-mismatch')
     }
     session.committed = true
-    session.touchedAt = Date.now()
+    this.touch(session)
     return { uploadId }
   }
 
@@ -116,13 +130,28 @@ export class SkillUploadSessionService {
     identity: SkillUploadBeginRequest['package']
   ): Promise<{ archivePath: string; cleanup(): Promise<void> }> {
     const session = this.sessions.get(uploadId)
-    if (!session?.committed || JSON.stringify(session.package) !== JSON.stringify(identity)) {
+    if (!session) {
       throw new Error('skill-upload-session-unavailable')
     }
-    session.touchedAt = Date.now()
+    if (this.expired(session)) {
+      await this.cancel(uploadId)
+      throw new Error('skill-upload-session-unavailable')
+    }
+    if (!session.committed || JSON.stringify(session.package) !== JSON.stringify(identity)) {
+      throw new Error('skill-upload-session-unavailable')
+    }
+    this.sessions.delete(uploadId)
+    this.clearIdleTimer(session)
+    let cleaned = false
     return {
       archivePath: session.path,
-      cleanup: () => this.cancel(uploadId)
+      cleanup: async () => {
+        if (cleaned) {
+          return
+        }
+        cleaned = true
+        await rm(session.path, { force: true })
+      }
     }
   }
 
@@ -132,18 +161,43 @@ export class SkillUploadSessionService {
       return
     }
     this.sessions.delete(uploadId)
+    this.clearIdleTimer(session)
     await session.handle?.close().catch(() => undefined)
     await rm(session.path, { force: true })
   }
 
-  private requireActive(uploadId: string): UploadSession {
+  private async requireActive(uploadId: string): Promise<UploadSession> {
     const session = this.sessions.get(uploadId)
-    if (!session || session.committed || Date.now() - session.touchedAt > SESSION_IDLE_MS) {
+    if (!session || session.committed) {
+      throw new Error('skill-upload-session-unavailable')
+    }
+    if (this.expired(session)) {
+      await this.cancel(uploadId)
       throw new Error('skill-upload-session-unavailable')
     }
     return session
   }
 
+  private expired(session: UploadSession): boolean {
+    return Date.now() - session.touchedAt >= this.idleMs
+  }
+
+  private touch(session: UploadSession): void {
+    session.touchedAt = Date.now()
+    this.clearIdleTimer(session)
+    session.idleTimer = setTimeout(() => {
+      void this.cancel(session.id).catch(() => undefined)
+    }, this.idleMs)
+    session.idleTimer.unref()
+  }
+
+  private clearIdleTimer(session: UploadSession): void {
+    if (session.idleTimer) {
+      clearTimeout(session.idleTimer)
+      session.idleTimer = null
+    }
+  }
+
   private async initialize(): Promise<void> {
     this.initialized ??= (async () => {
       await rm(this.root, { recursive: true, force: true })
@@ -154,7 +208,7 @@ export class SkillUploadSessionService {
 
   private async prune(): Promise<void> {
     const expired = [...this.sessions.values()]
-      .filter((session) => Date.now() - session.touchedAt > SESSION_IDLE_MS)
+      .filter((session) => this.expired(session))
       .map((session) => session.id)
     await Promise.all(expired.map((id) => this.cancel(id)))
   }