feat: improve git integration

[kaminskypavel]

g turns from a list of changed files into a source control view shaped like VS Code's: the changes sit over a commit graph of HEAD and every local and remote branch, any commit unfolds into its files in place, and diffs read side by side. Everything stays read-only, and the reviewed marks, the tree and pull request diffs work as they did.

Contents

• ✨ What you get
  • 🌳 See the whole history
  • 🔍 Read diffs like an editor
• 🧭 How it flows
• ⚠️ Risk
• 🔧 Technical overview
• 📝 Notes

✨ What you get

🌳 See the whole history

• A commit graph under your changes: g
  • the newest 500 commits of HEAD, every local branch and every remote-tracking one
  • drawn the way git log --graph draws them, each lane in its own color, refs colored by kind (HEAD, local, remote, tag)
  • a clean checkout opens on HEAD's commit instead of flashing no changes in main
• Push and pull at a glance: ↑ and ↓
  • ↑ marks a commit HEAD's upstream lacks (a push would send it), ↓ one HEAD lacks (a pull would bring it)
  • the header counts both, as in ▾ GRAPH (5) ↑3 ↓1
• Commits open in place: Enter, → or a click
  • the commit unfolds into its files right under it, each diffed against the commit's first parent
  • ← or Enter folds it again, and the same keys fold a whole section on its header
  • the right pane reads the commit under the cursor: message, author, dates and --stat

🔍 Read diffs like an editor

• Side by side: Ctrl+s
  • old file left, new file right, line numbers on both, a removed line facing what replaced it
  • Ctrl+s flips to the unified diff and back, remembered across opens
  • a diff pane narrower than 90 columns shows the unified diff either way
• One list, one filter: ↑/↓, then type
  • the cursor walks from the changed files straight into the commits, across both headers
  • typing narrows both sections at once: files by path, commits by hash, ref or subject
• What stayed the same
  • reviewed ✓ marks (Ctrl+r) and the directory tree (Ctrl+t) behave as before
  • a pull request's diff (from / or v) lists its FILES with no graph
  • nothing in the sidebar writes to the repository

🧭 How it flows

flowchart LR
  U([User]) -->|"g"| V["DiffView sidebar"]
  V -->|"BACKGROUND READ"| S["git status: CHANGES"]
  V -->|"BACKGROUND READ"| L["git log --graph + rev-list: GRAPH"]
  V -->|"cursor row"| P{"right pane"}
  P -->|"changed file"| D1["git diff HEAD"]
  P -->|"commit"| D2["git show --stat"]
  P -->|"commit's file"| D3["git show sha -- path"]
  P -->|"header"| D4["git status --short --branch"]
  V -->|"Enter / → on a commit"| F["git show --name-status: files unfold"]
  D1 --> X["split_rows: side by side"]
  D3 --> X
  classDef changed fill:#fde68a,stroke:#b45309,color:#111
  class L,D2,D3,D4,F,X changed

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⚠️ Risk

Verdict: 🟢 Low risk: a TUI-only change to one modal that runs read-only git in the user's own checkout, off the event loop.

	Level	Why
🔒 Security & production	Low	No new surface: the TUI already shells out to git here; the new calls (log, show, rev-list, status) are read-only, take an argument vector (no shell), and every path goes after --. The DAEMON and the protocol are untouched.
⚡ Performance	Low	All reads run on the blocking pool through BACKGROUND READS. git log --graph --date-order -n 500 over every ref walks the history to sort it, which can take a second on a very large repository; the header shows (…) until it lands and nothing waits on it. The per-frame clone holds the commits behind Arcs.
🧩 Fit with the codebase	Low	Follows the DIFF VIEWER's own patterns: tickets and Answer variants, the diff cache, list_hit hit-testing, the tree's fold keys. The one new idea is a row space over two lists (side_select), which keeps every existing list method intact underneath.

Rollback: git revert undoes it all. The UI state gains diff_unified and diff_sidebar_width, which an older build ignores; it stops writing diff_files_width, so after a revert the file list opens once at its default width.

🔧 Technical overview

• Mechanism. DiffView gains log: Option<GitLog> and a place (ChangesHeader, Changes, GraphHeader, Graph). side_len / side_row / side_select lay one row space over the changed-file list and the graph, so ↑/↓, Ctrl+d/Ctrl+u, the wheel and clicks cross sections without the list code changing. The graph is git log --graph --date-order --decorate=full -n 500 HEAD --branches --remotes split into commits and connector lines, with rev-list --left-right HEAD...@{upstream} marking sides; unfolded commits read git show --name-status -M --diff-merges=first-parent. Side by side is git_diff::split_rows, computed once per diff in show_diff; each draw decides whether it fits (MIN_SPLIT_W), and shown_rows keeps scrolling on the layout drawn.
• Files. crates/nebula-tui/src/git_log.rs: new, the graph's read, parse, fold and pane loaders; crates/nebula-tui/src/app.rs: DiffView's place, sidebar mapping, split state and the two UI state keys; crates/nebula-tui/src/git_diff.rs: diff_for takes a commit, split_rows, a listing that settles the cursor instead of closing on a clean checkout; crates/nebula-tui/src/ui.rs: sidebar rows, lane glyphs and colors, the split draw; crates/nebula-tui/src/event_loop.rs and event_loop/activate.rs: keys, mouse, the open path, the new answers, persistence (diff_probe removed); crates/nebula-tui/src/view_jobs.rs: Answer::Log and Answer::CommitFiles.
• Not done. Staging, committing, fetch, pull and push stay out: this PR only reads. The first cut put the history behind a Ctrl+l mode that replaced the file list; one stacked sidebar, as in VS Code, keeps both in view and needs no mode. --all was left out because stash, notes and PR refs clutter the graph.
• Gate. make ci: cargo fmt --check clean; clippy adds no warning (the ones it prints are already on main); cargo test --workspace 1708 pass, 2 fail (tui_drag_past_the_pane_top_autoscrolls_and_copies_the_run, nebula_open_from_inside_a_session_raises_the_file_tabs), and both fail the same way on main without this change.

📝 Notes

• Branched from main at v0.42.0 (0f98b95), independent of Move a session to another worktree or project with m or a drag, and it carries on the same conversation there #118; no conflicts.
• No PROTOCOL VERSION change: TUI only, no nebula kill needed.
• The sidebar opens at a third of the modal until dragged, once for everyone, since the old saved width sized a bare file list.

🤖 Generated with Claude Code