Add mosaic launch <seat> with seat registration for the control board (#1504)

New package packages/seat and wrapper scripts/mosaic. `launch <seat>` writes
<dataRoot>/seats/<layout>/<seat>/registration.json and then execs the seat's
launch.sh unchanged; `seat task <seat> <text>` edits the task only. The board
reads registrations, matches by sessions directory, and lets a registered
task, project or workspace override the derived value with a source tag.
The four repository launch scripts register themselves unless already
registered or run with --check. Fleet launchers untouched; one-liner on the
plan page.

Review found the record path keyed by seat name alone (repo and fleet
"darkwing" would collide); fixed by keying on layout. Also: the Pi pin
refusal now names installed and required versions.

Tests: seat 15, control-board 89, launch scripts 5, registry 69, config 24.

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

packages/control-board/src/page.html

@@ -65,6 +65,7 @@
   .msg-text,.msg-error{display:block;max-width:36ch;overflow:hidden;text-overflow:ellipsis;white-space:nowrap}
   .task-text{display:block;max-width:28ch;overflow:hidden;text-overflow:ellipsis;white-space:nowrap}
   .unknown{color:var(--muted);font-style:italic}
+  .source{color:var(--muted);font-size:.75em;margin-left:.35em;white-space:nowrap}
   .detail-row td{background:var(--raised)}
   .detail-list{display:grid;grid-template-columns:auto 1fr;gap:4px 14px;margin:0;font-size:.85rem;font-family:var(--mono)}
   .detail-list dt{color:var(--muted);font-family:var(--font)}
@@ -184,6 +185,21 @@
     return '<button type="button" class="seen-toggle" data-seen="true"' + attrs + ' title="I have read this; hide it from Waiting on you until the agent writes again">Seen</button>';
   }
 
+  var SOURCE_LABEL = { "registration": "registered", "first-user-message": "first message", "tmux-pane": "tmux pane", "session-cwd": "session cwd", "workspace-git-root": "git root" };
+  function sourceLabel(source) { return SOURCE_LABEL[source] || source; }
+  function sourceTag(source) { return source ? '<span class="source" title="source: ' + esc(source) + '">' + esc(sourceLabel(source)) + "</span>" : ""; }
+  function fromSource(source) { return source ? " (from " + esc(sourceLabel(source)) + ")" : ""; }
+  function registeredText(reg) {
+    if (!reg) return "no (not started through mosaic launch)";
+    var parts = ["started " + esc(reg.startedAt || "—")];
+    if (reg.updatedAt) parts.push("task updated " + esc(reg.updatedAt));
+    if (reg.harness) parts.push("harness " + esc(reg.harness));
+    if (reg.pid) parts.push("pid " + esc(reg.pid));
+    if (reg.tmux && reg.tmux.session) parts.push("tmux " + esc(reg.tmux.session) + (reg.tmux.socket ? " (socket " + esc(reg.tmux.socket) + ")" : ""));
+    if (reg.layout) parts.push(esc(reg.layout) + " layout");
+    return parts.join("; ");
+  }
+
   function buildRowPair(rec, showProject) {
     var idx = rowIdx++;
     var key = (showProject ? "waiting:" : "group:") + [rec.project, rec.agent].join("/");
@@ -193,12 +209,14 @@
       ? '<span class="msg-error" title="' + esc(rec.lastError) + '">' + esc(rec.lastError) + "</span>"
       : '<span class="msg-text" title="' + esc(rec.lastAssistantText || "") + '">' + esc(rec.lastAssistantText || "—") + "</span>";
     var projectCell = showProject ? "<td>" + esc(rec.project) + "</td>" : "";
-    // Gate A fields: derived from the log and tmux, or "unknown". Never guessed.
+    // Gate A fields: from the seat's registration (mosaic launch), else derived
+    // from the log and tmux, else "unknown". Never guessed. The source tag on
+    // the row says which one is shown.
     var task = rec.task
-      ? '<span class="task-text" title="' + esc(rec.task) + '">' + esc(rec.task) + "</span>"
+      ? '<span class="task-text" title="' + esc(rec.task) + '">' + esc(rec.task) + "</span>" + sourceTag(rec.taskSource)
       : '<span class="unknown">unknown</span>';
     var activeProject = rec.activeProject
-      ? '<span title="' + esc(rec.workspace || "") + '">' + esc(rec.activeProject) + "</span>"
+      ? '<span title="' + esc(rec.workspace || "") + '">' + esc(rec.activeProject) + "</span>" + sourceTag(rec.activeProjectSource)
       : '<span class="unknown" title="' + esc(rec.workspace || "") + '">unknown</span>';
     var main =
       '<tr class="' + cls + '">' +
@@ -219,9 +237,10 @@
       '<dl class="detail-list">' +
       "<dt>Session ID</dt><dd>" + esc(rec.sessionId || "—") + "</dd>" +
       "<dt>Session file</dt><dd>" + esc(rec.sessionFile || "—") + "</dd>" +
-      "<dt>Task</dt><dd>" + (rec.task ? esc(rec.task) : "unknown") + "</dd>" +
-      "<dt>Active project</dt><dd>" + (rec.activeProject ? esc(rec.activeProject) : "unknown") + "</dd>" +
-      "<dt>Workspace</dt><dd>" + (rec.workspace ? esc(rec.workspace) : "unknown") + (rec.workspaceSource ? " (from " + esc(rec.workspaceSource) + ")" : "") + "</dd>" +
+      "<dt>Task</dt><dd>" + (rec.task ? esc(rec.task) : "unknown") + fromSource(rec.taskSource) + "</dd>" +
+      "<dt>Active project</dt><dd>" + (rec.activeProject ? esc(rec.activeProject) : "unknown") + fromSource(rec.activeProjectSource) + "</dd>" +
+      "<dt>Workspace</dt><dd>" + (rec.workspace ? esc(rec.workspace) : "unknown") + fromSource(rec.workspaceSource) + "</dd>" +
+      "<dt>Registered</dt><dd>" + registeredText(rec.registered) + "</dd>" +
       "<dt>Session cwd</dt><dd>" + esc(rec.cwd || "—") + "</dd>" +
       "<dt>Tmux session</dt><dd>" + tmux + "</dd>" +
       "<dt>Last activity</dt><dd>" + esc(rec.lastActivity || "—") + "</dd>" +