Redesign Cell Navigation Bar, Remove cell active blue bar & include cell execution time

[cindyytong]

As a Jupyter user I want an easy way to

• easily run and stop cells
• understand at a glance what's executing, what's queued, and what's stale

Key considerations:

1. Visual indicators that don't clutter
2. Accessibility best practices
3. Queue visibility when multiple cells are running
4. Stale cell indicators for changed but not rerun cells
5. Established design patterns that are familiar

Design states to consider:

1. Cell that has not been run
2. Running a cell and scrolling away from it while it is running
3. Queued cell
4. Errored cell
5. Stopping a cell
6. Cell with only 1 line of code
7. Cell with multiple lines of code
8. Cell with wide outputs

Expected changes:

1. Move run cell button into the cell navigation bar, ensure that wehn a cell is running we still show the stop button and some visual affordance for the cell is running
2. Move cell navigation bar to the left
3. Remove cell active blue bar and instead use the cell outline to indicate active, hover, unselected cell
4. Move cell execution status to bottom row of code cell. This execution stats should use different icons for running cell, completed cell, errored cell, queued cell
5. Include cell run time and Last executed time in this row

[cindyytong]

added item 6 in expected changes

[rodrigosf672]

Verified Fixed

Positron Version(s) : 2026.02.0 build 109
OS Version          : macOS Tahoe 26.2

Test scenario(s)

• Cell navigation bar positioned on the left for all code cells
• Run button present inside the cell navigation bar
• No active blue bar shown on selected cells
• Active cell indicated via cell outline styling
• Hover and unselected outlines visible/uncluttered
• Never-run cell shows “not executed” status in the bottom row
• Execution status displayed in the bottom row (not the top)
• Running cell shows “running” icon/state
• Running indicator remains visible when scrolled away
• Multiple executions show queued cells with distinct “queued” icon/state
• Queue state readable when several cells are executing
• Stop button shown while a cell is running
• Stopping a cell updates status to the correct stopped/cancelled state
• Errored cell shows distinct error icon/state
• Completed cell shows distinct success icon/state
• Cell run time displayed after completion (e.g., seconds)
• “Last executed” timestamp displayed and updates on rerun
• Edited cell shows stale indicator until rerun
• Single-line cell layout remains clean with nav bar + bottom status row
• Multi-line cell spacing and alignment remain consistent
• Wide outputs do not overlap or misalign nav bar or status row
• Icons include accessible labels/tooltips and states not color-only
• Keyboard navigation still highlights the active cell via outline

Observation

Last run time (x secs/mins ago) only updates once new cells are created. Check that this is expected or if filing new issue would be needed. cc @dhruvisompura @cindyytong @testlabauto