feat(config): add kitty tab bar with git info and split-launch shortcut

dot_config/kitty/tab_bar.py

@@ -0,0 +1,215 @@
+#!/usr/bin/env python
+# ── tab_bar.py · kitty tab titles: directory + git state ──
+#
+# kitty loads this file from the config dir and exposes `draw_title` as the
+# `{custom}` field of tab_title_template (see kitty/tab_bar.py:
+# load_custom_draw_title). kitty keeps drawing the powerline chrome itself; only
+# the text inside a tab comes from here.
+#
+# A title reads:   2  chezmoi  main ⇡1 +2 ~1 ?3
+#                  ^  ^        ^         ^  ^  ^
+#                  |  dir      branch    staged / unstaged / untracked files
+#                  tab index
+#
+# git is *never* run on the render path. `draw_title` only ever reads a cache
+# and notes which working dirs are on screen; a 1s repeating kitty timer (main
+# thread, same as every other kitty callback) starts `git status` processes,
+# reaps the finished ones, and marks the tab bar dirty when a value changed.
+# Output goes to a temp file, not a pipe, so a repo with thousands of dirty
+# files can never fill a 64K pipe buffer and wedge the child.
+
+from __future__ import annotations
+
+import os
+import subprocess
+import tempfile
+import time
+from typing import Any
+
+from kitty.boss import get_boss
+from kitty.fast_data_types import add_timer
+
+# Nerd Font glyphs (VictorMono Nerd Font Mono covers all of these).
+FOLDER = '\uf07b'  # nf-fa-folder
+BRANCH = '\ue0a0'  # nf-pl-branch
+AHEAD = '\u21e1'
+BEHIND = '\u21e3'
+
+# A cached git summary is reused for this long; a working dir that stopped being
+# displayed is dropped after PRUNE_AFTER so closed tabs stop being polled.
+TTL = 4.0
+PRUNE_AFTER = 30.0
+POLL_INTERVAL = 1.0
+MAX_CONCURRENT = 4
+KILL_AFTER = 15.0
+MAX_DIR_LEN = 24
+
+# wd -> git summary spec: (branch, ahead, behind, staged, unstaged, untracked,
+# conflicts) or None when wd is not a work tree.
+_git: dict[str, tuple[str, int, int, int, int, int, int] | None] = {}
+_fresh_until: dict[str, float] = {}
+_wanted: dict[str, float] = {}
+_running: dict[str, tuple[subprocess.Popen[bytes], Any, float]] = {}
+_timer = 0
+
+
+def draw_title(data: dict[str, Any]) -> str:
+    global _timer
+    if not _timer:
+        _timer = add_timer(_tick, POLL_INTERVAL, True)
+    wd = data['tab'].active_wd
+    fmt = data['fmt']
+    parts = [str(data['index'])]
+    if wd:
+        _wanted[wd] = _now()
+        parts.append(f'{FOLDER} {_dir_label(wd)}')
+        summary = _git.get(wd)
+        if summary is not None:
+            parts.append(_render_git(summary, fmt))
+    else:
+        parts.append(data['title'])
+    return ' '.join(parts)
+
+
+def _dir_label(wd: str) -> str:
+    home = os.path.expanduser('~')
+    if wd == home:
+        return '~'
+    name = os.path.basename(wd.rstrip('/')) or wd
+    if len(name) > MAX_DIR_LEN:
+        name = name[: MAX_DIR_LEN - 1] + '…'
+    return name
+
+
+def _render_git(
+    summary: tuple[str, int, int, int, int, int, int], fmt: Any
+) -> str:
+    branch, ahead, behind, staged, unstaged, untracked, conflicts = summary
+    # color2/3/4/1 are palette slots, so the active Omarchy theme picks the
+    # actual greens and reds; fg.tab restores the tab's own foreground so the
+    # powerline chrome keeps drawing in its own colors.
+    tab = fmt.fg.tab
+    out = [f'{BRANCH} {branch}' if branch else BRANCH]
+    for count, mark, color in (
+        (ahead, AHEAD, fmt.fg.color6),
+        (behind, BEHIND, fmt.fg.color6),
+        (staged, '+', fmt.fg.color2),
+        (unstaged, '~', fmt.fg.color3),
+        (untracked, '?', fmt.fg.color4),
+        (conflicts, '!', fmt.fg.color1),
+    ):
+        if count:
+            out.append(f'{color}{mark}{count}{tab}')
+    return ' '.join(out)
+
+
+def _now() -> float:
+    return time.monotonic()
+
+
+def _tick(timer_id: int | None) -> None:
+    now = _now()
+    changed = _reap(now)
+    for wd, last_wanted in tuple(_wanted.items()):
+        if now - last_wanted > PRUNE_AFTER:
+            del _wanted[wd]
+            _git.pop(wd, None)
+            _fresh_until.pop(wd, None)
+            continue
+        if len(_running) >= MAX_CONCURRENT:
+            break
+        if wd in _running or _fresh_until.get(wd, 0.0) > now:
+            continue
+        _start(wd, now)
+    if changed:
+        for tm in get_boss().os_window_map.values():
+            tm.mark_tab_bar_dirty()
+
+
+def _start(wd: str, now: float) -> None:
+    try:
+        out = tempfile.TemporaryFile()
+        proc = subprocess.Popen(
+            (
+                'git',
+                '--no-optional-locks',
+                'status',
+                '--porcelain=v2',
+                '--branch',
+                '--untracked-files=normal',
+            ),
+            cwd=wd,
+            stdout=out,
+            stderr=subprocess.DEVNULL,
+            stdin=subprocess.DEVNULL,
+            # start_new_session, not preexec_fn: kitty is multi-threaded, and
+            # only the former is implemented without running Python between
+            # fork and exec.
+            start_new_session=True,
+        )
+    except OSError:
+        # No git, or wd vanished: remember "not a repo" so we stop retrying
+        # until the TTL lapses.
+        _git[wd] = None
+        _fresh_until[wd] = now + TTL
+        return
+    _running[wd] = (proc, out, now)
+
+
+def _reap(now: float) -> bool:
+    changed = False
+    for wd, (proc, out, started) in tuple(_running.items()):
+        rc = proc.poll()
+        if rc is None:
+            if now - started > KILL_AFTER:
+                proc.kill()
+            continue
+        del _running[wd]
+        summary = None
+        if rc == 0:
+            try:
+                out.seek(0)
+                summary = _parse(out.read().decode('utf-8', 'replace'))
+            except OSError:
+                summary = None
+        out.close()
+        if _git.get(wd, ...) != summary:
+            changed = True
+        _git[wd] = summary
+        _fresh_until[wd] = now + TTL
+    return changed
+
+
+def _parse(text: str) -> tuple[str, int, int, int, int, int, int]:
+    """git status --porcelain=v2 --branch -> title counts.
+
+    Header lines carry the branch and the ahead/behind pair; `1`/`2` records
+    carry a two-char XY status (X = index, Y = work tree), `?` is untracked and
+    `u` is unmerged. Renames (`2`) put the old path after a tab on the same
+    line, so line-splitting stays correct.
+    """
+    head = oid = ''
+    ahead = behind = staged = unstaged = untracked = conflicts = 0
+    for line in text.splitlines():
+        if line.startswith('# branch.oid '):
+            oid = line[13:20]
+        elif line.startswith('# branch.head '):
+            head = line[14:]
+        elif line.startswith('# branch.ab '):
+            for token in line[12:].split():
+                if token.startswith('+'):
+                    ahead = int(token[1:] or 0)
+                elif token.startswith('-'):
+                    behind = int(token[1:] or 0)
+        elif line[:2] in ('1 ', '2 '):
+            xy = line[2:4]
+            if xy[0] != '.':
+                staged += 1
+            if xy[1] != '.':
+                unstaged += 1
+        elif line.startswith('? '):
+            untracked += 1
+        elif line.startswith('u '):
+            conflicts += 1
+    branch = oid if head in ('', '(detached)') else head
+    return branch, ahead, behind, staged, unstaged, untracked, conflicts