Module folder_picker 

FolderPickerController — engine-level folder/workspace directory picker.

Owns all state for an interactive directory-browsing modal: filesystem walking, fuzzy filtering, scroll, and selection. Renders via the existing Palette primitive (no new Backend trait method needed) and accepts backend-neutral UiEvents.

Relation to vimcode

Extracted verbatim from vimcode’s TUI-local FolderPickerState (src/tui_main/mod.rs, ~285 lines). After the quadraui PR lands, vimcode removes the TUI-local code and rewires both TUI and GTK OpenFolderDialog through this controller.

Adoption status

The vimcode migration above hasn’t landed as of #825’s audit — no confirmed external adopter yet. Kept public rather than demoted: full TUI + GTK demo coverage already exists (examples/tui_folder_picker.rs, examples/gtk_folder_picker.rs, examples/common/folder_picker_app.rs) plus a TuiDriver end-to-end test in tests/tui_example_driver.rs, and the extraction above is a concrete, named migration target, not a speculative one.

Usage pattern

// Instantiate when the user triggers "Open Folder":
let mut picker = FolderPickerController::new(
    std::env::current_dir().unwrap(),
    vec![],       // no extra file names to surface
    false,        // don't show hidden dirs
);

// In AppLogic::render:
let rect = /* palette popup bounds */;
picker.render(rect, backend);

// In AppLogic::handle:
let visible_rows = /* rect.height as usize - PALETTE_CHROME_ROWS */;
match picker.handle(&event, visible_rows) {
    FolderPickerEvent::Confirmed { path } => { /* open workspace */ },
    FolderPickerEvent::Cancelled             => { /* dismiss modal */ },
    FolderPickerEvent::Consumed              => { /* redraw */ },
    FolderPickerEvent::Ignored               => {},
}

Scroll accounting

handle() requires visible_rows — the number of list rows visible inside the palette chrome (title row + query row + optional scrollbar row). Consumers typically compute this as rect.height as usize - PALETTE_CHROME_ROWS where PALETTE_CHROME_ROWS = 4.

Structs

FolderPickerController

Cross-backend compose controller for a directory-browsing picker modal.

Enums

FolderPickerEvent

What happened after FolderPickerController::handle processed an event.

Constants

DEFAULT_IGNORE_DIRS

Default heavy build/dependency directory names that are skipped during the filesystem walk.

DEFAULT_MAX_DEPTH

Default recursion depth for FolderPickerController::new.

PALETTE_CHROME_ROWS

Overhead rows consumed by the Palette chrome (title + query + borders).