[Feature]: Expose thread rename to agents via the t3-code MCP server (t3_thread_rename)

[Hugo-Persson]

Area

apps/server (t3-code MCP server), packages/contracts

Problem or use case

Thread titles are auto-generated from the first prompt, and users can rename a thread from the sidebar or chat header (right-click → Rename, double-click the title). None of that is reachable by the agent running inside the thread.

That matters for long-running threads whose purpose changes mid-way. A typical session starts as "Implement ENG-847", at this point the agent can rename. The agent knows exactly what the thread is about at every point, but the only way to keep the title accurate is for the user to stop and rename it by hand.

The rest of the thread surface is already moving towards agent access: the orchestrator work in #2829 adds t3_thread_start, t3_thread_list, t3_thread_read, t3_thread_send, t3_thread_wait and t3_thread_interrupt. Renaming is the obvious gap in that set. Today the shipped MCP server only exposes the preview_* tools.

Proposed solution

Add a t3_thread_rename tool to the t3-code MCP server, alongside the planned thread tools.

• Input: { threadId?: string, title: string }. When threadId is omitted, rename the thread the calling agent is running in.
• Reuse the existing rename validation and persistence path (trimmed, non-empty title, same limits the inline editor enforces) so behaviour matches the UI.
• Emit the same thread-updated event the sidebar already listens to, so the title changes live without a stale-title flash (see fix(web): no stale-title flash after renaming a thread #7822 for the flash case).
• Respect the same permission model as other side-effecting MCP tools, so plan mode does not rename threads before approval ([Bug]: Plan mode performs real write / side-effecting actions (file edits, git commits, MCP tool calls) before the plan is approved #3744).
• Add a work-log presentation entry ("Rename", "Renaming", "Renamed", "a T3 thread") next to the other t3_thread_* entries in packages/client-runtime/src/work-log/presentation.ts.

Optional follow-ups once the tool exists:

• A user setting to let agents rename threads automatically, similar to the auto-naming from feat: support ai generated thread names #990.
• A thread.rename keybinding ([Feature]: Expose more actions as bindable keybinding commands #4641, feat(web): add an opt-in shortcut to rename the active thread #11430) and this tool would then share one code path.

Related

• feat(orchestrator): introduce new orchestrator #2829 orchestrator with t3_thread_* MCP tools
• [Feature]: Expose more actions as bindable keybinding commands #4641 tracking bindable thread.rename command
• feat(web): add an opt-in shortcut to rename the active thread #11430 open PR for a thread.rename shortcut
• feat: support ai generated thread names #990 AI-generated thread names
• [Bug]: MCP-created thread IDs exceed the HTTP snapshot route limit #8860 the only existing issue touching MCP-created threads (ID length, unrelated to naming)

[juliusmarminge]

Duplicate of #7333 — same ask for agent-callable thread title update/rename via the t3-code MCP server.

Open #2829 already includes this on its head (t3_thread_update with action: "rename" / regenerate, from stacked #8690). Please continue there / on #7333.