v0.28.0

Nebula v0.28.0 is out. Markdown rendered as a page, comments on pull requests and issues without leaving the keyboard, PR sessions in the PR's own checkout, a harness registry with Muse on board, collapsible panels, five more themes, a Project tab in Settings, and an idle reaper that no longer kills an agent mid-job.

📖 Read and reply in place

• Markdown as a page. A .md is a rendered page wherever nebula shows one: the file tabs an agent's nebula open raises, an ⌥-click or f on a markdown path (read first, Enter for the editor, m for the source), the tree browser's preview (b, Ctrl+r flips to the source and back), and the issue and pull-request reading panes for GitHub bodies. Headings, lists, quotes, tables, task lists, alerts, links, and fenced code with the tree browser's own highlighting.
• Comment and edit without leaving. y on a pull request row opens a comment box and Enter posts it as you through gh pr comment; in the issues modal (i) c comments on the issue and E edits its title and description in the reading pane's place through gh issue edit. A post gh refuses brings the box back with your text intact.
• Issues open on rows. Once the cursor has rested on a project its open issues are fetched in the background and kept fresh every couple of minutes, so i paints at once instead of on an empty pane.

🔀 Pull requests get their own checkout

• PR sessions in the head branch. n (or m / right-click) on an OPEN PRS row now starts the session in a checkout of the pull request's head branch — the project's worktree already on it, or one the daemon cuts — instead of the project's root worktree. That checkout lists directly under its pull request, stepped in behind a └, and the Sessions column folds to a rule while the cursor rests on the PR itself.
• A preset on a pull request. e on an OPEN PRS row is a picker: choose one of your agent presets and it launches as a PR session, the PR's rule in the system prompt and the preset's prefix + task + postfix as the first prompt. A skip-task preset launches straight from the picker.

🔌 Run any CLI, and keep it running

• A harness registry. One harnesses map in config.json drives the n picker, e presets, spawn, resume, hooks and session titles; the Agents tab grows one section per entry, and nebula config harnesses prints the merged table. Muse ships as a built-in, and a third-party CLI such as Grok is a config block — no rebuild. Settings › Agents › hide_uninstalled_harnesses keeps the picker to CLIs found on PATH. Thanks @kaminskypavel (#79).
• Background jobs are not idle. The idle reaper used to take an agent whose backgrounded tool call was still running — Claude's run_in_background Bash or Monitor watch, a Codex shell command — because the hook-fed status read the turn's Stop as finished. It now reads the process tree: a job detached from the agent's terminal keeps the session up, and the idle clock restarts when that job ends (#78).

🫥 Shape the screen

• Collapsible panels. Projects, Worktrees and Sessions collapse to a slim rail with a chevron rather than vanishing, Shift+S folds the Sessions panel at last, and Ctrl+B (or ⌘B, or Shift+Z under tmux) collapses every panel and the workspaces bar at once — expanding never steals focus. Persisted under the existing hide_* keys and in Settings › Appearance. Thanks @kaminskypavel (#77).
• Five more themes. Settings › Appearance › theme adds lavender, coral, slate, sand and a grayscale mono beside the five you had.
• A Project tab. Settings › Project holds the rows that belong to the selected project, stored under projects by repo path — so far Hide root worktree, which moves there from Experimental. The old top-level hide_root_worktree stays as the fallback for projects without an entry.

curl -fsSL https://raw.githubusercontent.com/AgentSystemLabs/nebula/main/install.sh | sh