Brian Krabach
140 lines
7.3 KiB
Markdown
140 lines
7.3 KiB
Markdown
# Session Sidebar Design
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## Goal
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Add a collapsible left-side sidebar to the terminal (expanded) view that shows a live-updating session list with snapshot previews, usable as a session switcher while actively working in a terminal session.
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## Background
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The current workflow requires returning to the dashboard to switch sessions or see what's happening in other terminals. A persistent sidebar in the terminal view eliminates that round-trip, giving users at-a-glance visibility into all sessions while keeping the active terminal front and center.
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## Approach
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Pure frontend addition — no backend or coordinator changes. The sidebar consumes the same `sessions` data already fetched by the poll loop, reuses the existing `openSession()` function for switching, and relies entirely on CSS for layout transitions and responsive behaviour. New code is limited to a `renderSidebar()` function and associated styles.
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## Architecture
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### Layout
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`view-expanded` becomes a flex row with two children:
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```
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┌──────────────────────────────────────────────────┐
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│ view-expanded (display: flex; flex-direction: row) │
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│ ┌────────────┐ ┌──────────────────────────────┐ │
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│ │ .session- │ │ .terminal-container │ │
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│ │ sidebar │ │ (flex: 1) │ │
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│ │ (200px) │ │ │ │
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│ │ │ │ │ │
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│ │ .sidebar- │ │ │ │
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│ │ header │ │ │ │
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│ │ .sidebar- │ │ │ │
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│ │ list │ │ │ │
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│ └────────────┘ └──────────────────────────────┘ │
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└──────────────────────────────────────────────────┘
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```
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### Data Flow
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```
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poll tick
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├── renderGrid(sessions) ← dashboard (unchanged)
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└── renderSidebar(sessions, name) ← sidebar (new, same data)
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```
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No extra network requests. `renderSidebar` skips work when the dashboard view is active.
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## Components
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### 1 — Layout and Structure
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- `view-expanded` container: `display: flex; flex-direction: row`.
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- `.session-sidebar`: fixed `width: 200px`, positioned left.
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- `.sidebar-header`: title text + toggle button.
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- `.sidebar-list`: `overflow-y: auto`, scrollable card list.
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- `.terminal-container`: `flex: 1`, fills remaining width.
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- Collapse: toggling `.sidebar--collapsed` sets `width: 0; overflow: hidden` with a CSS transition (`0.25s ease`).
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- Toggle button: sidebar icon (`⋮⋮` or hamburger) in the expanded view header bar next to the existing back button. Secondary `‹`/`›` chevron at the sidebar's right edge in wide (side-by-side) mode only.
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- State persisted in `localStorage('muxplex.sidebarOpen')`.
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### 2 — Session Cards
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Each entry in `.sidebar-list` is a compact card:
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```
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┌─────────────────────────────────┐
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│ ● session-name [bell 2] │ ← header row: name + badge
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├─────────────────────────────────┤
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│ last line of output │
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│ $ some command running... │ ← snapshot preview, bottom-anchored
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│ (blank) │
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└─────────────────────────────────┘
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```
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- Card height: ~120px (header ~32px + 4–6 lines of 11px monospace preview).
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- Snapshot preview: same `lastLines` data already on each session, same `position: absolute; bottom: 0` bottom-anchoring CSS already shipped, restyled for narrower column.
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- Active session card: 3px left border in `var(--accent-cyan)`, slightly elevated background (`var(--bg-surface)`).
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- Click handler: calls existing `openSession(name)`. Clicking the active session's card is a no-op.
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- Session order: mirrors coordinator response order (bell-priority on mobile, natural order on desktop) — no new sorting logic.
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### 3 — Data Flow and State
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Two pieces of state:
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| Variable | Type | Source | Purpose |
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|---|---|---|---|
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| `currentSession` | `string \| null` | Set by `openSession(name)`, cleared by `closeSession()` | Determines which card gets active highlight |
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| `sidebarOpen` | `boolean` | `localStorage('muxplex.sidebarOpen')` | Controls `.sidebar--collapsed` CSS class |
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- `renderSidebar(sessions, currentSession)` is called alongside the existing `renderGrid(sessions)` on every poll tick — same data, zero extra network requests.
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- `renderSidebar` only does visible work when the terminal view is active. If the dashboard is showing, the sidebar DOM exists but rendering is skipped.
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- On `openSession`, the sidebar gets an initial render before the first poll tick catches up.
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- `sidebarOpen` toggle applies/removes `.sidebar--collapsed` — animation is CSS-only, no JS timers. Value written back to localStorage on every toggle.
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### 4 — Responsive / Overlay Behaviour
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**Breakpoint: 960px** viewport width.
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| Mode | Width | Sidebar Position | Animation | Chevron |
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| Side-by-side | ≥960px | In-flow, flex child | `width: 0/200px` | `‹`/`›` at right edge |
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| Overlay | <960px | `position: fixed; left: 0; top: 0; height: 100%` | `transform: translateX(-100%/0)` 0.25s ease | None |
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- In overlay mode the terminal stays full-width — nothing shrinks.
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- Clicking anywhere on `.terminal-container` closes the overlay.
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- Single toggle button always lives in the expanded header bar regardless of mode.
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- Default `sidebarOpen`: `true` on wide screens, `false` on narrow (when no localStorage value exists). Stored value respected on subsequent visits regardless of current screen width.
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## Error Handling
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- Empty sessions array: `renderSidebar` produces an empty list — no crash, no error state.
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- Session names are HTML-escaped before rendering to prevent injection.
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- `localStorage` read/write wrapped defensively — if unavailable, defaults apply and toggle still works for the current page session.
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## Testing Strategy
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Unit tests in `frontend/tests/test_app.mjs`, three groups:
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### `buildSidebarHTML` output
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- Active session card gets `.sidebar-item--active` class; non-active cards do not.
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- Bell badge renders when `unseen_count > 0`; absent when 0 or null.
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- Session name is HTML-escaped (injection check).
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- Empty sessions array produces an empty list, no crash.
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- Snapshot preview uses bottom-anchored last-lines approach.
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### Sidebar state
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- `sidebarOpen` written to `localStorage` on every toggle.
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- Default value: `true` when no stored value exists and viewport is wide; `false` when narrow.
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- `.sidebar--collapsed` class added/removed in sync with stored value.
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### Session switching
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- Sidebar card click calls `openSession(name)` with the correct session name.
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- Clicking the active session's card is a no-op.
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### Not unit-tested
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CSS breakpoint behaviour and overlay slide animation are verified by visual inspection during implementation — not unit-testable.
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## Open Questions
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None — all sections validated.
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