feat: Interactive sessions — terminal + agent chat for repo pods

[jonwiggins]

Summary

Add a first-class Session concept to Optio — persistent, interactive workspaces scoped to a repository pod. Sessions give users direct access to repo pods via a web terminal and (in phase 2) an interactive Claude Code chat, with full PR lifecycle tracking.

Motivation

Currently Optio is fire-and-forget: submit a task, wait for a PR. Users have no way to interactively work within a repo pod — explore code, run commands, iterate with an agent, or manage multiple PRs in a single working session.

Design

Sessions as a first-class entity

• Not a task — sessions are tracked separately with their own data model, lifecycle, and UI
• Own worktree: each session creates a worktree off latest main on a branch named session/<username>/<short-id>
• Persist until closed: sessions stay active until the user explicitly ends them (no auto-timeout)
• Don't count against task concurrency (maxConcurrentTasks)
• Cost tracking: token spend tracked per session

Phase 1: Terminal + PR tracking

• Data model: sessions table — id, repoUrl, userId, worktreePath, branch, state (active/ended), podId, costUsd, createdAt, endedAt
• Session PRs: session_prs table — tracks all PRs opened during a session with CI status, review status, merge state
• xterm.js web terminal: full terminal connected to pod exec, landing in repo root worktree
• PR detection: same approach as tasks — parse output for PR URLs
• PR lifecycle badges: CI status, review status, merged/closed — follows repo settings (review trigger, auto-merge)
• UI notifications: alert users when CI passes, PR merges, or review requests changes (no auto-fix, just notify)
• Session list: shown on overview page and repo detail page, separate from task list
• Session detail page (/sessions/:id): terminal + PR tracker + "End Session" button
• End session warning: popup warns that all un-pushed work will be lost
• Active session count: displayed per-repo and globally

Phase 2: Agent chat + split pane

• Long-running Claude Code process: interactive claude session exec'd in the pod, stdin/stdout piped through WebSocket
• Chat UI: streaming responses rendered in a chat pane
• Split pane layout: agent chat (left) + terminal (right), resizable, either pane collapsible
• Review triggers: users can request review agent on any session PR
• Cost tracking: per-session token spend displayed in UI

API routes (planned)

• POST /api/sessions — create a new session (provisions worktree)
• GET /api/sessions — list sessions (filterable by repo, state)
• GET /api/sessions/:id — session detail
• POST /api/sessions/:id/end — end session (cleanup worktree, warn about unpushed work)
• GET /api/sessions/:id/prs — list PRs tracked in this session
• WS /ws/sessions/:id/terminal — xterm.js WebSocket connection
• WS /ws/sessions/:id/chat — agent chat WebSocket connection (phase 2)

UI entry points

• "New Session" button on repo detail page (next to repo pod)
• "New Session" button on overview page per workspace pod
• Sessions section on overview and repo detail pages (separate from tasks)

Non-goals (for now)

• Control plane agent ("chat with Optio") — separate feature
• Multiple terminal tabs per session
• Auto-fix CI failures from sessions

[jonwiggins]

Optio is working on this issue.

Task ID: f51bb0bb-27e5-4dd8-8996-f7e06206950e
Agent: claude-code

[jonwiggins]

✅ Optio completed this issue. Changes merged in #93.