[Bug]: schedule_task on a linked environment fails when the project uses the environment's default model #37291

Before submitting

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

Area

apps/server

Steps to reproduce

This is the part of #19342 that is still open. The triage comment said that #22732 fixed t3_thread_launch, and asked for a new issue for schedule_task.

1. Link two environments, A and B. On B, set a default model in Settings → Threads (Claude Opus 5.5, effort high). Leave the project's own model on Inherit.
2. In a thread on A, have the agent call schedule_task with the environmentId of B and the id of a project on B. Use a fixed_time schedule and bindToCurrentThread: false.
3. Control: set defaultModelSelection on the same project with t3_project_update, and call schedule_task again with the same input.

Expected behavior

schedule_task uses the model that a new thread in that project on B gets. That is the project override if one exists, else the default model of B.

Actual behavior

Step 2 fails on all four projects that I tried. The error is under Logs.

Step 3 succeeds. On B, settings.json sets defaultModelSelection to Claude Opus 5.5 with effort high, and sets projectSettingsFolded: true. The project overrides have no defaultModelSelection.

B receives the forwarded call as the session of the link, with no calling thread (PeerForwarding.ts#L105). So schedule_task on B has no parent model, and falls back to projectDefaultModelSelection (OrchestratorMcpService.ts#L2236). That function reads only project.defaultModelSelection from the project record (L1284-L1294). Since #22732, t3_thread_launch uses the effective defaults of the project for a caller with no thread. schedule_task does not.

The open PR #35002 adds an optional target to schedule_task. Without a target, it keeps this fallback and this error.

Impact

Minor bug or occasional failure

Version or commit

0.1.10-nightly.20261115.4723

Environment

Target environment B: Linux, T3 Code server 0.1.10-nightly.20261115.4723. Calling environment A: Linux, 0.1.10-nightly.20261113.4643. Agent: Claude Code (Claude Opus 5.5) through the T3 MCP server.

Logs or stack traces

invalid_request: Project <projectId> has no default model, so this caller cannot pick one for it.

Screenshots, recordings, or supporting files

No response

Workaround

Set defaultModelSelection on the project record with t3_project_update. Only a thread in full-access mode can call it. The UI setting does not help, because it writes to projectSettingsOverrides in settings.json, which this check does not read.