GeezerVison

…layout and commands

why: WorkspaceBuilder sends SIGWINCH (via select_layout) and commands
(via send_keys) to panes before their shell finishes initializing (#365,
open since 2018). With zsh, this triggers the PROMPT_SP partial-line
marker — an inverse+bold "%" — because:

  tmux: screen_reinit() sets cx=cy=0 on new panes (screen.c:107-108).
    select_layout → layout_fix_panes → window_pane_resize enqueues a
    resize, and window_pane_send_resize delivers SIGWINCH via
    ioctl(TIOCSWINSZ) on the pane's PTY (window.c:449).

  zsh: preprompt() (utils.c:1530) runs the PROMPT_SP heuristic
    (utils.c:1545-1566) before every prompt. It outputs the
    PROMPT_EOL_MARK (default: "%B%S%#%s%b") to detect partial lines,
    then pads with spaces and returns the cursor. When SIGWINCH arrives
    mid-init, the interrupted redraw leaves the marker visible.

what:
- Add _wait_for_pane_ready() that polls cursor position until it moves
  from origin (0,0), indicating the shell has drawn its prompt
- Call readiness check before select_layout in iter_create_panes() so
  SIGWINCH only arrives after the shell can handle resize gracefully
- Wait for all default-shell panes, not just those with commands (blank
  panes via "- pane" shorthand expand to shell_command: [])
- Remove redundant select_layout call in build() that doubled SIGWINCH
  signals after each pane yield
- Add tests for readiness detection, timeout, call count, and layout
  deduplication

…iness check

why: The except block in _wait_for_pane_ready discarded the exception
traceback, making it impossible to diagnose pane refresh failures.
what:
- Add exc_info=True to logger.debug call in the except block

…ness skip coverage

why: The window_config.get("window_shell") fallback path at builder.py:566
was untested. Only pane-level shell: had fixture coverage.
what:
- Add skips_all_panes_with_window_shell fixture to PANE_READINESS_FIXTURES
- Verifies expected_wait_count=0 when window_shell is set

…c scope

why: The readiness skip for panes with shell/window_shell was undocumented,
making it unclear to future maintainers why pane_shell is None is the check.
what:
- Add comment explaining that shell/window_shell runs a command launcher,
  not an interactive shell, so there is no prompt to wait for

…o 5s

why: The 2s timeout was too tight for slow environments, causing
flaky doctest failures when the shell hadn't drawn its prompt yet.
what:
- Bump _wait_for_pane_ready doctest timeout from 2.0 to 5.0 seconds

why: Tmux doctests are inherently timing-sensitive — shell startup
races can cause spurious failures even with generous timeouts.
what:
- Add pytest_collection_modifyitems hook to apply flaky(reruns=2)
  marker to DoctestItems from DOCTEST_NEEDS_TMUX modules