docs(quick-1): complete arrow key navigation and directory description plan

.planning/STATE.md

@@ -80,10 +80,13 @@ Recent decisions affecting current work:
 - [Phase 04-03]: try_recv drain loop per poll iteration — drains all queued events, debounce collapses burst into single reload
 - [Phase 04-03]: FileWatcher initialized in main.rs before App::new() — avoids self-referential ownership, keeps constructor pure
 - [Phase 04-03]: Non-fatal watcher failure — warning printed, None passed to App, app runs without live reload
+- [quick-1]: Bare Left/Right match arms placed after Alt+Left/Alt+Right guards — match order ensures Alt combos consumed first
+- [quick-1]: BufReader + take(20) for frontmatter parsing — avoids loading entire large files
+- [quick-1]: span_len covers only [name] bracket not description — keeps Tab-cycling highlight correct
 
 ### Pending Todos
 
-None. Project complete.
+None. Project complete. Quick task 1 executed.
 
 ### Blockers/Concerns
 
@@ -95,5 +98,5 @@ All blockers resolved:
 ## Session Continuity
 
 Last session: 2026-03-01
-Stopped at: PROJECT COMPLETE — Completed 04-03-PLAN.md (final plan)
+Stopped at: Completed quick-1 (arrow key navigation + directory descriptions)
-Resume file: N/A — project complete
+Resume file: N/A — project complete, quick task 1 done

.planning/quick/1-arrow-key-navigation-and-directory-descr/1-SUMMARY.md

@@ -0,0 +1,89 @@
+---
+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