feat(web): regenerate thread titles from sidebar

[t3dotgg]

Thread titles can stop reflecting the conversation as work evolves, while Sidebar v2 only supports replacing them manually.

This adds a Regenerate title action that sends recent thread context and the previous title through the configured text-generation model. The server keeps the work off the provider command queue, preserves manual renames made while generation is running, and capability-gates the action for version-skewed environments.

Testing

• 96 focused contract, prompt, environment, and reactor tests
• Typechecked contracts, client-runtime, server, and web
• Targeted lint and formatting checks

Generated by gpt-5.6-sol with the Codex harness in T3 Code.

---

Note

Medium Risk
Touches orchestration events, projection schema, and async reactor behavior with race handling; changes are well-tested but span server read models and UI state sync.

Overview
Adds thread title regeneration so sidebar titles can be refreshed from recent conversation context instead of only manual renames.

Client: Sidebar v2 exposes Regenerate title (single and bulk) when threadTitleRegeneration is advertised; rows dim and show busy state while titleRegeneration is pending. Commands use thread.meta.update with regenerateTitle: true (not combined with an explicit title).

Server orchestration: The decider records pending regeneration on meta-update and applies thread.title.regeneration.complete only when requestId still matches; archiving clears pending state. SQLite migration 035 stores title_regeneration_request_id / title_regeneration_started_at on projection_threads, wired through projections, snapshots, and the client thread reducer.

ProviderCommandReactor: Handles thread.meta-updated with regenerateTitle on a dedicated worker: builds bounded conversation context (8k chars, up to 4 attachments), calls text generation with previousTitle, then dispatches completion. Manual renames and superseded requests are not overwritten; stale completions after archive/unarchive are ignored. On startup, interrupted pending regenerations are cleared via correlated completion dispatches.

Contracts / text generation: New capability flag, ThreadTitleRegeneration on threads, and regeneration-aware title prompts across providers.

^{Reviewed by Cursor Bugbot for commit 74d120a. Bugbot is set up for automated code reviews on this repo. Configure here.}

Note

Add thread title regeneration from the sidebar context menu

• Adds 'Regenerate title' to per-thread and multi-select sidebar context menus; the item shows a disabled 'Regenerating…' state when a regeneration is in progress.
• Introduces a thread.meta.update command flag regenerateTitle and a new internal thread.title.regeneration.complete command to drive the full regeneration lifecycle through the orchestration layer.
• The ProviderCommandReactor processes thread.meta-updated events with regenerateTitle=true, formats bounded conversation context, calls generateThreadTitle, and handles supersession (concurrent renames or newer requests) and retry on dispatch failure.
• On startup, the reactor clears any pending titleRegeneration state left over from a previous session. Archiving a thread also clears pending state.
• Adds DB migration 035 to add title_regeneration_request_id and title_regeneration_started_at columns to projection_threads, and exposes a threadTitleRegeneration capability flag in the server environment descriptor.
• buildThreadTitlePrompt gains a previousTitle path that adjusts instructions and uses tail-preserving truncation to keep the most recent conversation content.

^{Macroscope summarized 74d120a.}

[coderabbitai]

Important

Review skipped

Auto reviews are disabled on this repository. Please check the settings in the CodeRabbit UI or the .coderabbit.yaml file in this repository. To trigger a single review, invoke the @coderabbitai review command.

⚙️ Run configuration

Configuration used: Repository UI

Review profile: CHILL

Plan: Pro Plus

Run ID: 658b5f30-41cc-4fd5-a783-62ee9fc3e478

You can disable this status message by setting the reviews.review_status to false in the CodeRabbit configuration file.

Use the checkbox below for a quick retry:

• 🔍 Trigger review

---

Thanks for using CodeRabbit! It's free for OSS, and your support helps us grow. If you like it, consider giving us a shout-out.

❤️ Share

• X
• Mastodon
• Reddit
• LinkedIn

_{Comment @coderabbitai help to get the list of available commands.}

[macroscopeapp]

Approvability

Verdict: Needs human review

This PR introduces a new user-facing feature (thread title regeneration) with database schema changes, new async worker logic, and complex state management for handling concurrent operations. The scope and new runtime behavior warrant human review.

^{You can customize Macroscope's approvability policy. Learn more.}

[cursor]

Cursor Bugbot has reviewed your changes using high effort and found 1 potential issue.

^{❌ Bugbot Autofix is OFF. To automatically fix reported issues with cloud agents, enable autofix in the Cursor dashboard.}

^{Reviewed by Cursor Bugbot for commit a4d16a9. Configure here.}