Show task, active project and workspace per control board row (#1503)

Gate A fix asked by the professor session on Jason's behalf. Each row
now carries three derived fields, shown as "unknown" when the log and
tmux do not hold them:

- task: the session's first user message (pi logs have no task envelope)
- workspace: the live pane path of the pane running pi, else session cwd
- activeProject: basename of the nearest git checkout above the workspace

tmuxInspect replaces the bare liveness call in the CLI and returns
{ alive, workspace }; tmuxIsAlive stays as a wrapper. The grouping column
and seen.json keys are unchanged. Fixture test per field, tmux parse
tests, page test; missing launcher signals are recorded in the plan page.

Co-Authored-By: Claude Fable 5.1 <[email protected]>

docs/plans/2026-09-12_control-board-mvp.md

@@ -50,6 +50,25 @@ Acceptance:
 
 ### Step 3 log
 
+**2026-09-12 — Gate A fix: task, active project and workspace per row.**
+Asked by the professor session on Jason's behalf. Each row now shows
+Task (the session's first user message), Active project (basename of the
+nearest git checkout above the workspace) and, in the detail row,
+Workspace (the live `#{pane_current_path}` of the pane running `pi`, else
+the session log's `cwd`). Anything that cannot be derived shows the word
+"unknown". Missing signals, for launchers: (1) pi session logs carry no
+task envelope entry, so Task is the free-text first user message, which
+for fleet seats is a fleet-comms envelope and for hand-started seats is
+whatever was typed ("resume", "who are you?"); a launcher that wants a
+clean task label should emit one as the first line of the first message
+or write a per-seat status file the scanner can read. (2) Neither
+`roster.yaml` nor a seat's `profile.json` names a project, and every fleet
+seat runs in `~/.mosaic`, which is itself a git checkout, so Active
+project reads `.mosaic` for all of them; a `project` field in the roster
+would fix that. (3) Workspace is only live while a `pi` pane exists; for
+offline seats it is history from the log. Fixture test per field, a
+tmux-inspect parse test, and a page test (79/79). Sonnet review: APPROVED, no findings.
+
 **2026-09-12 — liveness follows the tmux pane, not just the session.**
 Jason found agents marked "waiting" that were actually dead: their tmux
 session still existed but no longer ran `pi` (it had exited to a shell or