Context projection relationships

UX rules

• Sidebar focus drives both secondary projections. A worktree or session spotlights its Git lineage and reveals/spotlights its process group. A project drives its process groups; it has no single Git lineage.
• Git focus derives context from the cursor row. A worktree row uses its path; a commit uses its lane identity. The owning worktree or unmounted local branch receives the sidebar's quiet unfocused marker. Worktree context also reveals and spotlights the corresponding process group.
• Processes focus derives context from the clicked process's worktree attribution. The owning worktree receives the sidebar marker and its Git lineage remains spotlighted while Processes keeps focus.
• A context change lands every projection regardless of focus. Session activation, a process click, or a pin arriving from outside the projections (alt+tab over a focused session, Recent's walk) moves the sidebar selection — the semantic join — and the graph and process cursors follow it. Only the driving projection's own cursor is exempt: re-landing it would yank it off the row the user chose.
• Contextual spotlighting is not the transient type-to-filter query. It does not prune rows or mutate scope; unrelated rows recede and the relevant row is revealed. After a selected-row click pins the filter, clicking another contextual row moves both selection and pin while keeping filter mode. Arrow-key navigation does the same on every new landing; it never reads as the repeated-click gesture. Clicking the pinned row again clears the filter, and escape clears it from any of the three projections (after backing out of any type-to-filter query/scope first, one rung per press).
• alt+tab is the visual filter's keyboard toggle: with no pin live it pins the focused projection's selected context, and with one live it lifts the filter. In a terminal or agent session it pins that session's owning worktree. While Recent (cmd+e) is up it pins the highlighted row's owning worktree without closing the list, and a live pin follows the walk from row to row; the close settles the join, landing the sidebar selection on the pinned context (mid-walk the panes belong to the previews). Elsewhere outside the projections it pins the sidebar selection, the semantic join. See the keyboard map's Visual filter section.
• Project folders in the sidebar browse first: the first click parks the selection on the folder and lands every projection on that project; only a repeat click on the already-selected folder expands or collapses it (return folds immediately — keyboard selection already sits on the row). Because that repeat click is the fold toggle, pointer-pinned filters never start from the folder itself, only from descendant worktree, branch, or agent rows — though a live pin follows folder clicks and arrow landings like any contextual row. alt+tab has no such click conflict and may pin the project folder, receding every other project.
• Branch-only Git lanes can mark an unmounted branch in the sidebar, but they cannot filter Processes because no worktree exists to own a process.
• Context changes swap pane content, never pane membership. Following a context with no session keeps the tile in place as a generic empty pane, which can be filled with any pane type — browsing from any projection must not add, remove, or resize panes.