T3 Code adds cross-provider child agents in its upcoming nightly overhaul

• Cross-provider child agents are coming to T3 Code's next nightly: T3 Code creator theo says delegate_task can spawn children on any provider or model.
• Threads gain MCP controls, mid-thread provider switching and automatic resumption after limits reset, according to theo's feature list.
• The rollout carries an explicit instability warning: theo's heads-up says the team cut one more stable release before merging the overhaul.

Pi keeps its own extension and project-trust discovery, while T3 injects a namespaced MCP bridge. The orchestration V2 PR describes nine persistence migrations covering event logs, subagents, scheduled tasks and legacy imports.

The shared delegate_task tool lets an agent start children on any provider or model. The accompanying thread features include:

• Lineage: native subagents appear as child threads with their model, status and history.
• Context attachment: @ a thread name, or drag a thread from the sidebar, to attach it as context.
• Durability: the Pi implementation gives T3's delegated children durable threads.

Durable child threads are the keeper here.

The rollout adds three sets of agent controls:

• Thread MCP: create, launch, message, wait on, read, search and interrupt threads.
• Thread metadata: rename threads, regenerate titles, link PRs and settle threads.
• Workspace MCP: hand off worktrees, plus list and close previews.

T3 Code expands its integrations along four paths in theo's announcement:

• Pi: a new provider integration.
• ACP Registry: add registry agents including Devin, Cline, Kimi and Droid.
• Cursor: the official Cursor SDK replaces the CLI integration that theo described as broken.
• OpenCode: version 2 support.

Pi communicates over stdio JSONL RPC through the user's own installation, according to the adapter PR. User-installed Pi subagent extensions surface progress cards without resumable native child sessions, a separate behavior from T3's durable delegate_task children.

Threads gain five execution features in theo's rollout list:

1. Server-side queueing and steering.
2. Automatic resumption when usage limits reset.
3. Scheduled tasks.
4. Thread forking.
5. Provider or model switching in the middle of a thread.

The V2 runtime adds backend components beneath those controls:

• Event and projection stores.
• Command receipts and an effect outbox.
• Provider-session and run-execution services.
• Checkpoint capture, rollback and context-handoff services.

Running threads can be hidden until they need attention. During the beta discussion, theo described the tradeoff as less distraction at the cost of some spatial consistency in the sidebar.

The inbox-style sidebar treats threads as unfinished tasks, with two automatic cleanup mechanisms:

• Settle a thread when its PR merges.
• Clean up threads untouched for three days.

Idea grouping is also in progress, theo said in a reply.

Subagents often burn substantially more tokens for marginal latency gains, pvncher argued in the discussion, with improvements depending on task parallelism. Strict reporting chains can also slow execution without a gain.

He separately warned that handing work to cheaper models can reduce overall quality even under a smart orchestrator.

Separately, zeeg previewed an MCP and agent-toolchain overhaul linked to Sentry's toolkit. He said in a reply that both MCP and CLI interfaces would ship, with authentication friction a focus.

The toolkit README documents remote MCP middleware over the Sentry API, plus a work-in-progress stdio transport for self-hosted deployments.

The overhaul targets the next nightly after one final stable release. theo warned of instability and rapid follow-up changes over the following days.

The branch had been reviewed for months, with most changes arriving through separate PRs, theo said in a follow-up. He described nightlies as a way to reduce the blast radius of broken code and assumptions beyond real-world and programmatic testing.

The hide-threads feature also had two remaining bugs under repair in his later update.