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[Bug]: Swift iOS: tapping a delegated task in the Agents sheet fails with thread_not_found#17643

openedOct 9, 2026byBben-vargas

Opened on behalf of Ben by Claude Code (Opus 5.5).

Before submitting

  • I searched existing issues and did not find a duplicate.
  • I included enough detail to reproduce or investigate the problem.

Area

apps/mobile (experimental SwiftUI client, apps/swift-ios)

Steps to reproduce

  1. In a thread on a desktop host, have the agent call the delegate_task MCP tool (for example a Codex child task) and let it finish.
  2. On iPhone, open the same thread in the Swift app (TestFlight).
  3. Open the Agents sheet. The delegated task shows as Completed.
  4. Tap the task row.

Expected behavior

The child thread opens, the same as it does on web and desktop.

Actual behavior

The app shows Could not open thread: thread_not_found. The child thread exists. t3_thread_read and desktop both open it.

Delegated-task thread IDs contain literal % characters, for example thread:delegated-task:command%3Amcp%3A<uuid>%3Adelegate-task%3A<clientRequestId>. The Swift client percent-encodes the ID twice, so it requests a thread that does not exist:

1GET /api/orchestration/threads/thread:delegated-task:command%25253Amcp%25253A…/bounded

The server decodes the path once and looks up command%253Amcp… instead of command%3Amcp….

On t3code/rebuild-mobile-app-swift @ 52912fe7e3:

  1. apps/swift-ios/Core/OrchestrationV2Client.swift:325 (threadPath) encodes the ID once. It removes /?#% from .urlPathAllowed, so %3A becomes %253A and : is left alone.
  2. apps/swift-ios/Core/HTTP.swift:767 (endpoint) assigns that already-encoded path to URLComponents.path. That setter expects an unencoded path and escapes % again, so %253A becomes %25253A.

HTTPClient.threadSnapshot (HTTP.swift:274) pre-encodes with .urlPathAllowed and goes through the same endpoint, so it double-encodes too. Ordinary thread IDs are UUIDs with nothing to escape, which is why only delegated-task children (and any other ID containing %) hit this.

A likely fix is to set components.percentEncodedPath = path in endpoint and keep the per-segment encoding in threadPath. Fixed paths such as /api/orchestration/shell are already valid encoded paths, so they are unaffected. A regression test could assert that thread ID thread:a%3Ab produces the request path /api/orchestration/threads/thread:a%253Ab/bounded.

Impact

Major degradation or frequent failure

Version or commit

Swift app: TestFlight build 60 (code reference: t3code/rebuild-mobile-app-swift @ 52912fe7e3). Server: 0.0.46-nightly.20261008.2849.

Environment

iOS 27, iPhone. macOS host running the Nightly desktop app, connected over Tailscale HTTPS. Child task: Codex gpt-6.1-sol.

Logs or stack traces

shell
1# server.trace.ndjson, http.server GET
2http.route: /api/orchestration/threads/:threadId/bounded
3url.path: /api/orchestration/threads/thread:delegated-task:command%25253Amcp%25253A9dd2e492-724d-437f-b41a-cdc6ec10ec65%25253Adelegate-task%25253Averify-t3-workflow-vs-flowition-r1/bounded
4user_agent: T3Code/60 CFNetwork/3896.100.1.2.1 Darwin/27.0.0
5
6# sql.transaction failure
7ProjectionStoreThreadNotFoundError: No orchestration projection exists for thread thread:delegated-task:command%253Amcp%253A9dd2e492-724d-437f-b41a-cdc6ec10ec65%253Adelegate-task%253Averify-t3-workflow-vs-flowition-r1.
8
9# actual thread ID
10thread:delegated-task:command%3Amcp%3A9dd2e492-724d-437f-b41a-cdc6ec10ec65%3Adelegate-task%3Averify-t3-workflow-vs-flowition-r1

Workaround

Open the child thread from desktop or web.