@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 (changed files with +/- stats, per-file diffs), and /pr reports the open pull request for the current branch. Both run only when invoked — nothing polls, because branch and worktree state already render in the session footer.

Key concepts

• On-demand, lazy runtime. The extension keeps a single ManagedRuntime (created by createRuntime()) that is allocated on first use and disposed on session_shutdown. All git/gh work runs as Effect programs through it.
• Effect-based command runner (src/process.ts). CommandRunner is an Effect Context.Service wrapping ChildProcessSpawner from effect/unstable/process. Spawn failures, nonzero exits, and timeouts are all normalized into a CommandResult — callers never handle thrown exceptions:
  • timeout → { code: -1, stderr, stdout } (via Effect.timeoutOrElse; child gets forceKillAfter: "5 seconds")
  • spawn/platform failure → code: 1, stderr prefixed with Failed to run <command>: <message>
  • real exit code otherwise
  • stdout/stderr are captured from piped streams with a 10 MiB cap; overflow appends \n[command output truncated]\n
• Untrusted text is sanitized before styling. Repository-controlled paths and diff text can contain terminal control sequences; sanitizeTerminalText strips OSC/CSI/escape sequences and stray control chars before any theme styling is applied.
• /lg pipeline (loadChangedFiles). git rev-parse --show-toplevel (null result → not a repo) → git status --porcelain=v1 -z --untracked-files=all (NUL-separated, rename/copy-aware pairing of old+new paths, deduped by new path) + git rev-parse --verify HEAD in parallel. Then, per file, two parallel git diff calls (timeout 10 s): --unified=3 --no-color --no-ext-diff for the diff and --numstat for +/- counts. Untracked files or a repo with no HEAD diff against /dev/null via --no-index (stats show binary/null when numstat reports -). Diffs are capped at 20 000 lines with a truncation marker; an empty diff renders as "No textual diff available."
• /lg overlay (showChangedFiles). A ctx.ui.custom overlay (anchor center, 95% width, up to 90% height) with a files sidebar + diff pane, two focus modes (files/diff), vim (j/k/g/G/h/l) and arrow-key bindings, ctrl-d/ctrl-u paging, and diff lines colored by type via the active theme (+ success, - error, @@ heading, ---/+++ muted, diff header accent). TUI-only — non-TUI sessions get a warning toast.
• /pr lookup (lookupPullRequest). git rev-parse --is-inside-work-tree → git branch --show-current (empty → "detached HEAD", no PR) → gh pr view <branch> --json number,url,state,isDraft (10 s timeout). Only state === "OPEN" results are reported as PRs; a nonzero gh exit or unparseable JSON means "no open PR."

API

Commands (registered via pi.registerCommand)

| Command | Description | Behavior | |---|---|---| | /lg | "Browse changed files and their diffs" | TUI-only (ctx.ui.notify warning otherwise). Loads changed files; null → "Not a git repository" (warning); empty → "Working tree is clean" (info); otherwise opens the overlay. Takes no args. | | /pr | "Show the open pull request for the current branch" | null → "Not a git repository" (warning); open PR → PR #<n> (draft): <url> (info, (draft) only when isDraft); else → No open PR found for <branch> (info). Takes no args. |

Both handlers accept (args, ctx) and honor ctx.signal — cancellation surfaces as "Loading changed files was cancelled." / "Pull request lookup was cancelled." errors.

Events (pi.on)

• session_shutdown — disposes the lazily-created ManagedRuntime (resets it to undefined so the next session re-creates it). Matters because leaked child-process resources would otherwise outlive the session.

Exported helpers (importable from the extension or its src/ modules)

• index.ts: gitInfo(pi: ExtensionAPI) — the default export registered as the extension.
• src/process.ts:
  • interface CommandResult { code: number; stderr: string; stdout: string }
  • CommandRunner — Effect Context.Service; run(command, args, cwd, timeout): Effect<CommandResult>
  • CommandRunnerLive — the Layer (provided NodeServices.layer) that implements the service
  • runCommand(command, args, cwd, timeout): Effect<CommandResult> — service accessor
• src/runtime.ts:
  • createRuntime() — builds a ManagedRuntime over CommandRunnerLive
  • runEffect(runtime, effect, { signal?, interruptMessage? }) — runs an Effect to completion; throws with interruptMessage on interruption-only causes, else throws the first pretty error
  • type GitInfoRuntime = ReturnType<typeof createRuntime>
• src/changed-files-view.ts:
  • loadChangedFiles(cwd): Effect<ChangedFile[] | null> — null = not a git repository
  • showChangedFiles(ctx: ExtensionContext, files: ChangedFile[]) — renders the TUI overlay (no-op outside TUI)
  • sanitizeTerminalText(text): string — strips terminal control sequences
  • interface ChangedFile { additions: number | null; deletions: number | null; diff: string[]; name: string; path: string }

Constants

• GIT_TIMEOUT_MS = 3_000 (index.ts repo/branch checks), GH_TIMEOUT_MS = 10_000 (gh pr view), diff/stat timeout 10_000 (changed-files-view), MAX_STREAM_CHARS = 10 MiB, MAX_DIFF_LINES = 20_000, DIFF_SCROLL_STEP = 5.

No tools (registerTool), no shortcuts (registerShortcut), and no config files — the extension is command-only.

Examples

1. Browse local changes. User: "what did I change locally?" → agent sends /lg. TUI opens the overlay: j/↓ select a file, enter/space/l/→ move to the diff pane, h/←/esc return, esc in the file pane closes. Each sidebar row shows › name +n -m (or binary); the second row per file shows its path.
2. Check for an open PR. User: "is there a PR for this branch?" → agent sends /pr → toast PR #42: https://github.com/owner/repo/pull/42. A draft prints PR #42 (draft): …; a branch with no open PR prints No open PR found for feature/x.
3. Non-repo / clean-tree handling. Running /lg outside a git work tree toasts "Not a git repository"; in a clean repo it toasts "Working tree is clean" — useful for confirming state without reading the footer.
4. Programmatic reuse. Another extension can call runEffect(createRuntime(), loadChangedFiles(cwd)) to get the ChangedFile[] list (or null) without opening the TUI, or use sanitizeTerminalText before rendering any git-sourced text.