Codex Desktop omits codex_app project/thread tools with a custom Responses provider

Independent reproduction with DeepSeek (2026-08-05)

Same build and symptom reproduced with the DeepSeek official custom provider (deepseek-v4-flash, wire_api = "responses", API-key auth, no OpenAI login). Session rollout 019fd492-b9b3-7163-abae-0b910f1f8c58 shows the thread tools ARE registered in dynamic_tools, but only in the deferred group:

• deferLoading: true: automation_update, fork_thread, handoff_thread, get_handoff_status, list_projects, create_thread, list_threads, read_thread, wait_threads, send_message_to_thread, set_thread_pinned, set_thread_archived, set_thread_title
• direct (visible): navigate_to_codex_page, read_thread_terminal, load_workspace_dependencies

The captured Responses request to DeepSeek includes {"type":"tool_search",...} plus those three direct tools, but not the deferred thread tools. deepseek-v4-flash does not invoke tool_search, so the deferred group is unreachable — same behavior documented in https://github.com/CCanxue/codex-deepseek-subagent-fix for v1 multi-agent tools.

So the practical gap here is not "the app never registered the tools" — it registered them and then hid them behind a discovery mechanism the custom model won't call. This matches the related #36382/#31750 family.

Suggested fix direction (any one would unblock):

1. Do not defer first-party codex_app thread tools when the active provider/model cannot use tool_search; expose them directly.
2. Treat thread_tools as provider-independent instead of tied to the Statsig userID-gated feature flag (local Sentry scope shows gate 2395575782 cannot evaluate without a userID).
3. Add the namespace_tools = false / flatten escape requested in #36942 so custom-provider sessions can opt into plain function tools.

Full lab write-up: https://github.com/k421o/codex-deepseek-labs/issues/4

As of version Version 26.820.60940 on MacOS the tools seem to be available again.

Descriptions are concise paraphrases, not the internal manifest text.

Core execution

• functions.exec — Runs JavaScript that can coordinate nested tools.
• functions.wait — Waits for a previously yielded execution to produce more output.
• functions.request_user_input — Presents structured questions to the user; Plan mode only.

Shell and files

• exec_command — Runs a shell command in a managed terminal.
• write_stdin — Sends input to or polls an active terminal session.
• apply_patch — Creates or edits files using a patch.
• view_image — Loads a local image for visual inspection.

Planning and goals

• update_plan — Creates or updates a step-by-step task plan.
• create_goal — Starts an explicitly requested tracked goal.
• get_goal — Reads the active goal’s status and usage.
• update_goal — Marks an active goal complete or blocked.

MCP resources

• list_mcp_resources — Lists static resources exposed by MCP servers.
• list_mcp_resource_templates — Lists parameterized MCP resource templates.
• read_mcp_resource — Reads a selected MCP resource.

Codex tasks and projects

• list_projects — Lists available local, remote, and ChatGPT projects.
• list_threads — Lists recent and pinned Codex tasks.
• list_archived_threads — Lists archived tasks.
• read_thread — Reads another task’s recent status and messages.
• create_thread — Creates a separate user-owned task.
• fork_thread — Forks an existing task and its history.
• send_message_to_thread — Sends a follow-up prompt to another task.
• wait_threads — Waits for one or more tasks to finish or require attention.
• handoff_thread — Moves a task and its Git state between environments or hosts.
• get_handoff_status — Checks a task-handoff operation.
• navigate_to_codex_page — Opens a selected task in the main Codex window.
• set_thread_title — Renames a task.
• set_thread_pinned — Pins or unpins a task.
• set_thread_archived — Archives or restores a task.

Codex workspace and UI

• load_workspace_dependencies — Locates bundled runtimes and document-processing libraries.
• open_in_codex — Opens a file, terminal, browser tab, or code review in a Codex panel.
• read_thread_terminal — Reads this task’s current terminal output.

Automations

• automation_update — Creates, views, updates, pauses, or deletes scheduled automations and heartbeats.

Internal agent coordination

• spawn_agent — Starts a sub-agent on a delegated subtask.
• followup_task — Assigns another turn to an existing agent.
• send_message — Sends information to a running agent without starting a new turn.
• wait_agent — Waits for an agent to finish or report progress.
• interrupt_agent — Stops or redirects an agent.
• list_agents — Lists agents and their current states.