@tylerho/pi-git-info

On-demand /lg diff browser and /pr lookup for the current branch's local changes and open pull request.

Install

pi install npm:@tylerho/pi-git-info

Git info

Two on-demand git helpers for the interactive TUI. /lg opens a two-pane overlay for browsing local changes, with per-file addition and deletion counts and the diff for the selected file, and /pr reports the open pull request for the current branch. Both run only when invoked, because branch and worktree state already appear in the session footer, so nothing here polls.

How it works

The extension holds one ManagedRuntime from createRuntime(), which is CommandRunnerLive with NodeServices.layer provided. The runtime is allocated on first use, shared by both commands, and disposed on session_shutdown. Every git and gh call runs as an Effect program through it.

CommandRunner in src/process.ts is the command layer. It is an Effect Context.Service that wraps ChildProcessSpawner from effect/unstable/process, and it turns every outcome into a CommandResult so no caller handles a thrown exception:

• A timeout returns { code: -1, stderr, stdout } through Effect.timeoutOrElse. The child process gets forceKillAfter: "5 seconds".
• A spawn or platform failure returns code: 1 with the message prefixed as Failed to run <command>: <message>.
• Any other outcome carries the real exit code.
• Stdout and stderr stream from pipes. Each stream is capped at 10 MiB, and output past the cap ends with \n[command output truncated]\n.

Paths and diff text come from the repository, so sanitizeTerminalText strips OSC, CSI and escape sequences and stray control characters before the overlay applies theme styling. The same function cleans the display name and path on each file entry.

/lg loads through loadChangedFiles. It runs git rev-parse --show-toplevel first, and a nonzero exit means the directory is not a repository. Inside a repository it runs two commands in parallel: git status --porcelain=v1 -z --untracked-files=all, parsed as NUL-separated records where rename and copy records consume the following old path and entries are deduplicated by new path, and git rev-parse --verify HEAD, which reports whether a commit exists. A nonzero exit from the status command also returns null. Each changed path then gets two parallel git diff calls with a 10 second timeout: --unified=3 --no-color --no-ext-diff for the diff text and --numstat for the counts. An untracked file, or any file in a repository with no HEAD commit, diffs against /dev/null with --no-index. A numstat count of - becomes null and the file renders as binary. Diffs are capped at 20,000 lines with a truncation line, and an empty diff renders as No textual diff available.

showChangedFiles draws the overlay with ctx.ui.custom: anchored center, 95% width, up to 90% height, at least 60 columns. The body is max(8, floor(terminal rows * 0.8) - 2) lines tall. The files pane holds between 24 and 48 columns and gives each file a name row and a path row, so the pane scrolls by whole files, wraps at either end, and keeps the selected one in view. The diff pane fills the rest. Focus has two modes, files and diff, and the selected file's row takes selectedBg while the files pane has focus and customMessageBg while the diff pane does. In the files pane, j/k and the arrow keys move, g/G and home/end jump, enter, space, l or right opens the diff, and esc closes the overlay. In the diff pane, j/k and the arrow keys scroll by 5 lines, ctrl-d/ctrl-u page by half the body, g/G and home/end jump to an end, and esc, h or left returns to the files pane. Diff lines take a color from the active theme by line type: + success, - error, @@ mdHeading, --- and +++ muted, diff --git and index accent and bold, the truncation line warning. showChangedFiles returns without drawing when the session is not in TUI mode.

/pr resolves through lookupPullRequest. git rev-parse --is-inside-work-tree must exit 0 and print true. git branch --show-current gives the branch name, and an empty name reports the branch as detached HEAD. Then gh pr view <branch> --json number,url,state,isDraft runs with a 10 second timeout. parsePullRequest accepts the result only when number is a number, url is a string, and state is OPEN, and it sets isDraft only when the field is exactly true. A nonzero gh exit or unparseable JSON means no open PR.

API

Commands

Both handlers take (args, ctx) and pass ctx.signal into runEffect, so cancellation throws Loading changed files was cancelled. or Pull request lookup was cancelled.

Events

session_shutdown clears the stored runtime and disposes it, so the next session builds a new one. Disposal releases child process resources that would otherwise outlive the session.

Exports

• index.ts default export gitInfo(pi: ExtensionAPI).
• src/process.ts exports interface CommandResult { code: number; stderr: string; stdout: string }, CommandRunner (an Effect Context.Service tagged git-info/CommandRunner with run(command, args, cwd, timeout): Effect<CommandResult>), CommandRunnerLive (the layer that requires ChildProcessSpawner), and runCommand(command, args, cwd, timeout).
• src/runtime.ts exports createRuntime(), type GitInfoRuntime, and runEffect(runtime, effect, { signal?, interruptMessage? }). runEffect returns the value on success, throws interruptMessage (default Operation was aborted.) when the cause holds only interrupts, and throws the first pretty error message otherwise.
• src/changed-files-view.ts exports loadChangedFiles(cwd): Effect<ChangedFile[] | null>, where null means the directory is not a repository, showChangedFiles(ctx, files), which returns without drawing outside the TUI, sanitizeTerminalText(text), and interface ChangedFile { additions: number | null; deletions: number | null; diff: string[]; name: string; path: string }.

Constants

GIT_TIMEOUT_MS 3,000 for the repository and branch checks and GH_TIMEOUT_MS 10,000 for gh pr view in index.ts. MAX_STREAM_CHARS 10 MiB and TRUNCATED_MARKER in src/process.ts. DIFF_SCROLL_STEP 5 and MAX_DIFF_LINES 20,000 in src/changed-files-view.ts, where each diff and numstat command also uses a 10,000 ms timeout.

It registers no tools and no shortcuts, and reads no config file.

Examples

1. The user asks "what did I change locally?" and the agent sends /lg. The overlay opens on the files pane. j and down move through the file list, enter opens the highlighted file, and esc on the files pane closes the overlay. Each file takes two rows, a name row with +n -m (or binary) and a path row. The selected file's name row is prefixed with ›.
2. The user asks "is there a PR for this branch?" and the agent sends /pr. The notification reads PR #42: https://github.com/owner/repo/pull/42. A draft prints PR #42 (draft): ..., and a branch with no open PR prints No open PR found for feature/x.
3. Running /lg outside a git work tree notifies Not a git repository, and running it in a clean repository notifies Working tree is clean. Both confirm state without reading the footer.
4. Another extension can call runEffect(createRuntime(), loadChangedFiles(cwd)) to get the ChangedFile[] list, or the null that means no repository, without opening the overlay. sanitizeTerminalText is exported for any text that came from a repository.