FN-8453: unify concurrency accounting and indicators

Unify live-agent capacity accounting across engine and dashboard.

- Derive Running and Waiting from workflow traits and durable agent liveness.
- Apply unified limits to planner, executor, and merge admission while updating dashboard indicators.
- Remove duplicate concurrency controls and document the unified operator model.

Files changed:
 .changeset/fn-8453-unified-concurrency.md          |   7 +
 docs/agent-tool-surface-full-loop.md               |   4 +-
 docs/architecture.md                               |   2 +-
 docs/dashboard-guide.md                            |   4 +-
 docs/settings-reference.md                         |   4 +-
 .../skill/fusion/references/fusion-capabilities.md |   4 +-
 .../core/src/__tests__/live-agent-count.test.ts    |  91 ++++----
 packages/core/src/index.gate.ts                    |   6 +
 packages/core/src/index.ts                         |   6 +
 packages/core/src/live-agent-count.ts              | 107 ++++++---
 packages/dashboard/app/App.tsx                     |  28 ++-
 packages/dashboard/app/api/board-workflows.ts      |   2 +
 packages/dashboard/app/components/Column.tsx       |   6 +-
 .../dashboard/app/components/EngineControlMenu.tsx |  26 ---
 .../dashboard/app/components/ExecutorStatusBar.tsx |  38 ++-
 .../dashboard/app/components/SettingsModal.tsx     |   1 -
 .../app/components/__tests__/Column.test.tsx       |   6 +-
 .../__tests__/EngineControlMenu.test.tsx           |  10 +-
 .../__tests__/ExecutorStatusBar.test.tsx           |  32 ++-
 .../command-center/CommandCenterControls.tsx       |  26 ---
 .../settings/sections/SchedulingSection.search.ts  |   9 -
 .../settings/sections/SchedulingSection.tsx        |  13 --
 .../app/hooks/__tests__/useExecutorStats.test.ts   |  12 +-
 packages/dashboard/app/hooks/useExecutorStats.ts   |  50 ++--
 .../src/__tests__/project-store-resolver.test.ts   |  11 +-
 packages/dashboard/src/project-store-resolver.ts   |  14 +-
 .../register-config-mcp-pi-settings-routes.ts      |   3 +-
 packages/engine/src/__tests__/concurrency.test.ts  | 123 +++++++++-
 .../engine/src/__tests__/project-engine.test.ts    |  34 +++
 packages/engine/src/__tests__/triage.test.ts       |   7 +-
 packages/engine/src/concurrency.ts                 | 207 ++++++++++++++++-
 packages/engine/src/project-engine.ts              | 151 ++++++++++--
 packages/engine/src/scheduler.ts                   |  82 ++++++-
 packages/engine/src/triage.ts                      | 254 +++++++++++++--------
 .../lib/dashboard-browser-safe-core-modules.json   |   5 +
 35 files changed, 991 insertions(+), 394 deletions(-)

Fusion-Task-Id: FN-8453

Fusion-Task-Lineage: 12cfa5df-675d-4fce-b17e-932376544239

Co-authored-by: Fusion (runfusion.ai) <noreply@runfusion.ai>

scripts/lib/dashboard-browser-safe-core-modules.json

@@ -54,6 +54,11 @@
       "module": "detect-content-language",
       "reason": "2026-07-16: Language detection is pure shared string logic with an explicit Vite subpath alias.",
       "verifiedAt": "2026-07-16"
+    },
+    {
+      "module": "live-agent-count",
+      "reason": "2026-07-21: FN-8453 shares pure workflow-trait-based Running and Waiting predicates with dashboard capacity indicators; its dependency graph has no Node-only modules.",
+      "verifiedAt": "2026-07-21"
     }
   ]
 }