Arcanist
Weekly Update

01 - Engineering

Faster time to PR.

Sessions finish and open PRs faster than before.

• Rebuilt the post-execution pipeline — eliminated redundant typechecks, parallelized work that used to run sequentially, deferred blocking steps
• Removed hard caps on agent step budgets — Arcanist can now spend as many steps as the task actually needs instead of cutting off early
• Faster task classification at session start — less idle time before the agent begins working

02 - Engineering

Smarter context.

The agent picks better context before it starts working.

• Improved instruction document selection — Arcanist is better at choosing which project docs are relevant to your task
• Similar session context — Arcanist can now reference how it solved related tasks in the past
• Slack prompt attachments — attach files and context directly from Slack when kicking off a session

03 - Product

Better Slack experience.

Starting sessions from Slack is more reliable and intuitive.

• Smarter repo inference — Arcanist is better at figuring out which repo you mean from conversation context
• Threaded replies — replies stay in your thread instead of spawning new messages
• Linear issue context — when you reference a Linear ticket, Arcanist infers the right repo automatically

04 - Product

UI improvements.

• Collapsible sidebar on desktop — more room for the session view
• User prompts now render as markdown
• Smoother filter chip transitions on the session list
• Refreshed logo and design polish pass across the app
• Evals dashboard shows per-task failure detail

05 - Infrastructure

Reliability.

Fewer failed sessions, better recovery when things go wrong.

• Fixed sandbox startup flakes — eliminated a cold-boot race condition that could wedge sessions
• Fixed event delivery bugs — bridge reconnect, buffer overflow, and ordering issues resolved
• Evals runner crashes now detected and alerted automatically instead of failing silently
• Docker runtime support — repos that need Docker Compose now work out of the box

06 - Go-to-Market

GTM update.

• Picked up our first growth-stage design partner
• Learning a lot about the actual hair-on-fire problem for teams — "can't merge code no matter how fast we write it"
• Doing the most user interviews we've ever done
• Realizing a lot of people care about deploying their application in a sandbox — dev deploy as a service