feat(tui): collapsible sidebar with compact usage overview

[Zireael]

Summary

The Magic Context sidebar in OpenCode's TUI can now be collapsed into a compact 3-line view by clicking the header. This frees up sidebar space while keeping the most essential context information visible at a glance.

Suggestion 1 (I didn't implement this, but it could be a good idea): consider sorting the context categories by their size in context window. Currently the categories are displayed in static order (System ->Compartments ->Memories -> Conversation ->Tool Calls ->Tool Defs), which is also okay when you don't want to see categories jumping up and down because of re-sorting. But having an option to see a list of 'heaviest' categories taking space in context window would be preferable to some people.
Suggestion 2: Is there a separate category for 'Skills Defs', or are they bundled together with 'Tool Defs'? Skill definitions can bloat the context window as much as tool/MCP definitions, when you have too many packed in the .agents/ folders.

What changed

• Collapse via header click — clicking the Magic Context header toggles between the full expanded sidebar and a compact summary. The collapsed header shows real-time context usage (percentage and absolute tokens) instead of the brand title.
• State persisted across restarts — collapsed/expanded state is stored in api.kv, so it survives session restarts and window reloads.
• Compact color-coded token bar — the segmented usage bar shrinks to a single row with proportional flexGrow-based segments, filling the full sidebar width. Includes a "Free" segment (dim gray ░) for unused context, with token-count labels overlaid on wide-enough segments.
• Smart status line — the third line prioritises active operations: historian compacting, dreamer running, pending queue, or an at-rest summary of compartments/facts/memories.
• No visual gap — the <box marginTop={1}> wrapper that created a blank line between the collapsed header and the status bar is removed.

Under the hood, the bar rendering changed from fixed-character fill ("█".repeat(w)) to flexGrow-proportional segment boxes with backgroundColor, so the bar naturally stretches to the full row width regardless of the sidebar's rendered size.

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Summary by cubic

Make the Magic Context sidebar collapsible with a compact 3‑line overview that frees space while keeping usage visible. Compact bar labels are now configurable via tui.compact_bar in magic-context.jsonc; collapse state persists across restarts.

• New Features

  • Click the header to toggle collapse/expand (shows ▶/▼); expanded view is unchanged.
  • Collapsed header shows usage vs threshold and token counts (e.g., 47.5% / 65%, 111K / 180K).
  • Compact color‑coded bar fills the full width, adds a dim “Free” segment; width‑aware labels with optional “Free” suffix and thresholds from tui.compact_bar (label_threshold, free_label_threshold, show_free_label).
  • Smart status line prioritizes active work (historian, dreamer, queue) or shows compartment/fact/memory counts.
  • Added tui.sidebar.collapse_default and tui.compact_bar defaults to the schema; manual toggles still persist via KV and override defaults.

• Refactors

  • Replaced fixed-character bar with flexGrow segment boxes; removed the blank line under the header in collapsed mode.
  • Extracted helpers to sidebar-utils.ts (compactTokens, collapsedStatusLine, collapsedUsageLine) with tests in sidebar-utils.test.ts; reads config and threads options into the compact bar.

^{Written for commit af386db. Summary will update on new commits. Review in cubic}

[cubic-dev-ai]

No issues found across 3 files

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