---
phase: quick-1
plan: "01"
subsystem: navigation, directory-listing
tags: [arrow-keys, frontmatter, directory, vault]
dependency_graph:
  requires: []
  provides: [ARROW-NAV, DIR-DESC]
  affects: [src/app.rs, src/vault.rs]
tech_stack:
  added: []
  patterns: [yaml-frontmatter-parsing, bufreader-take]
key_files:
  created: []
  modified:
    - src/app.rs
    - src/vault.rs
decisions:
  - "Bare Left/Right go after Alt+Left/Right guards in match — Rust match guards ensure Alt+Left is consumed first"
  - "Read only first 20 lines via BufReader + take(20) — avoids loading large files for metadata"
  - "strip_span covers only [name] bracket, not description — keeps Tab-cycling highlight correct"
  - "78-char truncation budget applied after accounting for indent and separator widths"
metrics:
  duration: "5 min"
  completed: "2026-03-01T10:38:54Z"
  tasks_completed: 1
  files_modified: 2
---

# Quick Task 1: Arrow Key Navigation and Directory Descriptions Summary

**One-liner:** Bare Left/Right arrow keys navigate history and directory listing shows YAML frontmatter descriptions in DarkGray beside each file entry.

## What Was Built

### Part A — Bare arrow key navigation (src/app.rs)

Added two new match arms to `handle_key()` immediately after the `Alt+Left`/`Alt+Right` guarded arms:

```rust
KeyCode::Left => {
    self.navigate_back();
}
KeyCode::Right => {
    self.navigate_forward();
}
```

The match arm order is critical: the guarded `KeyCode::Left if key.modifiers.contains(KeyModifiers::ALT)` arms are checked first. Bare `Left`/`Right` fall through to the new unguarded arms only when `ALT` is not held. Updated the doc comment on `handle_key()` to document the new bindings.

### Part B — Frontmatter description parsing (src/vault.rs)

Added a `description: Option<String>` field to `DirEntry`.

Added `extract_frontmatter_description(path: &Path) -> Option<String>`:
- Opens the file with `BufReader` and reads at most 20 lines (`lines().take(20)`)
- Checks first line is exactly `---`
- Scans for `description:` key, stops at closing `---`
- Strips surrounding single or double quotes if present
- Returns `Some(value)` or `None`

Updated `list_vault_files()` to call `extract_frontmatter_description()` for each `.md` file and populate the field. Directory entries get `description: None`.

### Part C — Description display in directory listing (src/app.rs)

Updated `build_directory_lines()` to append description spans for file entries that have one:

```
  [filename]  description text here, truncated...
```

- Two-space separator (`"  "`) between the bracketed name and description
- Description rendered as `Span::styled(text, Style::default().fg(Color::DarkGray))`
- Truncation budget: `78 - indent_chars - span_len - 2`, appending `"..."` if clipped
- `link_records` entry's `span_len` covers only the `[name]` bracket — description is a separate span and not part of the link highlight range

## Deviations from Plan

None - plan executed exactly as written.

## Self-Check

- [x] `src/app.rs` modified — bare Left/Right arms present, description display in `build_directory_lines()`
- [x] `src/vault.rs` modified — `description` field on `DirEntry`, `extract_frontmatter_description()` helper, `list_vault_files()` populates field
- [x] `cargo build` — clean (0 new warnings)
- [x] `cargo clippy` — clean (all warnings pre-existing in unrelated files)
- [x] Commit `f0ec2ed` exists

## Self-Check: PASSED