FN-7666: record weekly test-velocity regression finding (gate 7.7s -> 36.3s)

Narrative: update the 2026-W28 test-velocity baseline report with the newly measured merge-gate/changed-test wall-time regression and document root-cause attribution.
- Bump baseline cycle to 2026-W28 (captured 2026-07-08T09:30:50.606Z)
- Update headline metrics table: gate 7.7s -> 36.3s (+28.6s), boot smoke 17.4s -> 25.3s (+7.9s), pnpm test 9.3s -> 43.4s (+34.0s), quarantine count unchanged at 1
- Add FN-7666 finding note attributing the regression to ~4,305 new re-exported source lines across 14 modules pulled through the @fusion/core / @fusion/engine barrels, inflating per-fork import/transform cost across the 18 curated engine-core gate files; confirms it is a genuine regression (not cache/env noise) via cold-vs-warm reruns; files follow-up FN-7667 for the barrel-decoupling fix
- Update weekly history table (previous/latest/delta rows) and the #leads post text block
- Append new row capturing this week's measurements to scripts/test-velocity-history.json

Files changed:
 docs/test-velocity-baseline.md     |  23 ++++----
 scripts/test-velocity-history.json | 112 +++++++++++++++++++++++++++++++++++++
 2 files changed, 123 insertions(+), 12 deletions(-)

Fusion-Task-Id: FN-7666

Fusion-Task-Lineage: 73ec627c-2fc6-4289-8e6e-3e839ed5c675

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

scripts/test-velocity-history.json

@@ -1361,6 +1361,118 @@
       "measurementFailures": [],
       "timingSnapshotCapturedAt": "2026-06-27T05:41:42.568Z",
       "timingNotes": []
+    },
+    {
+      "capturedAt": "2026-07-08T09:30:50.606Z",
+      "gateMs": 36301,
+      "bootSmokeMs": 25333,
+      "testMs": 43360,
+      "quarantineCount": 1,
+      "slowestTop20": [
+        {
+          "file": "packages/dashboard/src/__tests__/insights-routes.test.ts",
+          "ms": 26500,
+          "package": "@fusion/dashboard"
+        },
+        {
+          "file": "packages/engine/src/runtimes/__tests__/in-process-runtime.test.ts",
+          "ms": 24700,
+          "package": "@fusion/engine"
+        },
+        {
+          "file": "packages/dashboard/src/__tests__/workflow-routes.test.ts",
+          "ms": 22000,
+          "package": "@fusion/dashboard"
+        },
+        {
+          "file": "packages/core/src/__tests__/db.test.ts",
+          "ms": 21200,
+          "package": "@fusion/core"
+        },
+        {
+          "file": "packages/dashboard/app/components/__tests__/GitManagerModal.test.tsx",
+          "ms": 16900,
+          "package": "@fusion/dashboard"
+        },
+        {
+          "file": "packages/core/src/__tests__/mission-store.test.ts",
+          "ms": 16000,
+          "package": "@fusion/core"
+        },
+        {
+          "file": "packages/cli/src/__tests__/extension.test.ts",
+          "ms": 15700,
+          "package": "@runfusion/fusion"
+        },
+        {
+          "file": "packages/dashboard/app/components/__tests__/AgentPromptsManager.test.tsx",
+          "ms": 14800,
+          "package": "@fusion/dashboard"
+        },
+        {
+          "file": "packages/dashboard/app/components/__tests__/App.test.tsx",
+          "ms": 14600,
+          "package": "@fusion/dashboard"
+        },
+        {
+          "file": "packages/dashboard/app/components/__tests__/TaskDetailModal.inline-editing-and-integrations.test.tsx",
+          "ms": 14100,
+          "package": "@fusion/dashboard"
+        },
+        {
+          "file": "packages/dashboard/app/components/__tests__/TaskDetailModal.rendering.test.tsx",
+          "ms": 13700,
+          "package": "@fusion/dashboard"
+        },
+        {
+          "file": "packages/dashboard/src/__tests__/routes-auth.test.ts",
+          "ms": 13600,
+          "package": "@fusion/dashboard"
+        },
+        {
+          "file": "packages/core/src/__tests__/agent-store.test.ts",
+          "ms": 13400,
+          "package": "@fusion/core"
+        },
+        {
+          "file": "packages/engine/src/__tests__/workspace-merger-idempotency.test.ts",
+          "ms": 12700,
+          "package": "@fusion/engine"
+        },
+        {
+          "file": "packages/engine/src/__tests__/self-healing-workspace.test.ts",
+          "ms": 11800,
+          "package": "@fusion/engine"
+        },
+        {
+          "file": "packages/engine/src/__tests__/pr-response-run.test.ts",
+          "ms": 11600,
+          "package": "@fusion/engine"
+        },
+        {
+          "file": "packages/dashboard/app/components/__tests__/ListView.test.tsx",
+          "ms": 11300,
+          "package": "@fusion/dashboard"
+        },
+        {
+          "file": "plugins/fusion-plugin-compound-engineering/src/__tests__/sync.test.ts",
+          "ms": 11000,
+          "package": "@fusion-plugin-examples/compound-engineering"
+        },
+        {
+          "file": "packages/dashboard/app/components/__tests__/AgentDetailView.settings.test.tsx",
+          "ms": 10700,
+          "package": "@fusion/dashboard"
+        },
+        {
+          "file": "packages/dashboard/app/components/__tests__/SecretsView.test.tsx",
+          "ms": 10700,
+          "package": "@fusion/dashboard"
+        }
+      ],
+      "measurementFailures": [],
+      "timingSnapshotCapturedAt": "2026-06-27T05:41:42.568Z",
+      "timingNotes": []
     }
   ]
 }