# Color Palette Panel — Persistence & Layout Fixes

## Problem Statement

The iced GUI color palette panel has several issues:
1. **Colors don't persist between sessions** — bg color changes are never saved (bug in `BgColorChanged` handler), and save failures are silently ignored
2. **Reset button** should return to black/white (already works correctly)
3. **Recent colors don't persist** — same root cause as #1 (dirty flag issue)
4. **Panel minimum height** is too low (180px) — contents get clipped, especially the color wheel (220px canvas)

## Root Cause Analysis

### Bug 1: BgColorChanged never persists (PRIMARY ISSUE)

In `app.rs:2352-2356`, the `BgColorChanged` handler does NOT set `self.colors_dirty = true`:
```rust
Message::BgColorChanged(color) => {
    self.bg_color = color;
    // MISSING: self.colors_dirty = true;
    crate::shape_sync::sync_shape_from_tool(self);
    self.refresh_composite_if_needed();
}
```

Compare with `FgColorChanged` (line 2347) which DOES set it. This means background color changes are never written to disk.

### Bug 2: Save order issue

In `app.rs:8845-8848`, the dirty flag is cleared BEFORE the save:
```rust
if self.colors_dirty {
    self.colors_dirty = false;        // cleared first
    save_colors(...);                  // save second — if this fails, flag is already cleared
}
```

If `save_colors` fails (e.g., directory doesn't exist), the flag is already cleared and the save won't retry.

### Bug 3: Silent save failures

`save_colors()` uses `let _ = std::fs::write(...)` which discards errors. If `~/.config/hcie-iced/` doesn't exist, writes fail silently.

## Implementation Plan

### Step 1: Fix BgColorChanged persistence

**File:** `hcie-iced-app/crates/hcie-iced-gui/src/app.rs` (line ~2354)

Add `self.colors_dirty = true;` to the handler.

### Step 2: Fix save order

**File:** `hcie-iced-app/crates/hcie-iced-gui/src/app.rs` (line 8845-8848)

Swap the order — save first, then clear the flag:
```rust
if self.colors_dirty {
    save_colors(self.fg_color, self.bg_color, &self.recent_colors);
    self.colors_dirty = false;
}
```

### Step 3: Add directory creation in save_colors

**File:** `hcie-iced-app/crates/hcie-iced-gui/src/app.rs` (line 93-101)

Add `create_dir_all` before writing:
```rust
fn save_colors(fg: [u8; 4], bg: [u8; 4], recent: &[[u8; 4]]) {
    let path = colors_path();
    if let Some(parent) = path.parent() {
        let _ = std::fs::create_dir_all(parent);
    }
    // ... rest unchanged
}
```

### Step 4: Increase panel minimum height

**File:** `hcie-iced-app/crates/hcie-iced-gui/src/dock/sizing.rs` (line 70-73)

Change ColorPicker policy:
```rust
PaneType::ColorPicker => PaneSizePolicy {
    width: axis(180.0, 280.0, 380.0, 1),
    height: axis(300.0, 420.0, 500.0, 1),
}
```

Rationale for values:
- **Min 300px**: Shows swatch row, hex input, alpha slider, tab bar, and start of color wheel
- **Preferred 420px**: Shows full color wheel (220px canvas) + header + recent colors without scrolling
- **Max 500px**: Bounded to prevent stealing vertical space from sibling panels (Layers has grow_priority=35 vs color's 1)

### Step 5: Update test assertions

**File:** `hcie-iced-app/crates/hcie-iced-gui/src/dock/sizing.rs`

Tests to update:
1. `policy_values_prioritize_canvas_and_bound_color_picker` (line 437-441): Update preferred/max values
2. `subtree_constraints_follow_split_axis` (line 453): Update `height.max` assertion (Layers has INFINITY max, so shared axis max becomes INFINITY)
3. `color_picker_does_not_receive_vertical_surplus_with_list_sibling` (line 494): Update max bound check

## Files to Modify

1. `hcie-iced-app/crates/hcie-iced-gui/src/app.rs` — 3 changes (BgColorChanged fix, save order, create_dir_all)
2. `hcie-iced-app/crates/hcie-iced-gui/src/dock/sizing.rs` — policy update + 3 test updates

## Verification

1. Launch app, change both fg and bg colors, close and reopen — both should be restored
2. Click "D" button — fg=black, bg=white
3. Select several colors, close/reopen — recent colors preserved
4. Resize color palette pane to minimum — color wheel and recent colors visible
5. `cargo test -p hcie-iced-gui` — all tests pass