diff --git a/docs/evidence/cached-symbol-board-rejection-20260905.json b/docs/evidence/cached-symbol-board-rejection-20260905.json
new file mode 100644
index 0000000..38806f0
--- /dev/null
+++ b/docs/evidence/cached-symbol-board-rejection-20260905.json
@@ -0,0 +1,54 @@
+{
+  "schemaVersion": "fidc-cached-symbol-board-rejection/v1",
+  "measuredAt": "2026-09-05T03:22:00+08:00",
+  "host": "192.168.31.177",
+  "candidateCommit": "eb8b146",
+  "revertCommit": "f210539",
+  "candidate": {
+    "description": "precompute a symbol-id-aligned BJSE bit vector and share one suffix classifier between platform expressions and risk control",
+    "primaryHotEngineSeconds": [4.656, 4.759, 4.669, 4.698, 4.614],
+    "primaryHotMedianEngineSeconds": 4.669,
+    "acceptedPrimaryBaselineMedianEngineSeconds": 4.729,
+    "primaryObservedImprovementPercent": 1.2687661249735674,
+    "secondaryLowContentionEngineSeconds": [4.404, 4.327, 4.346],
+    "secondaryLowContentionMedianEngineSeconds": 4.346,
+    "acceptedSecondaryBaselineMedianEngineSeconds": 4.049,
+    "secondaryObservedRegressionPercent": 7.33514448011855,
+    "highContentionSecondaryEngineSecondsExcluded": [6.398]
+  },
+  "rollbackComparison": {
+    "primaryEngineSecondsExcluded": [12.736, 12.795, 12.899, 13.845],
+    "hostLoadAverage": 44.84,
+    "reason": "managed symbolic workers entered a roughly 30-core phase, so the rollback batch cannot serve as a same-load wall-time comparison"
+  },
+  "businessContract": {
+    "primaryTotalReturn": 0.9219861819172002,
+    "primaryTradeCount": 26088,
+    "primaryCanonicalSha256": "b42fea66237d06eadb24f6b8c9e2760e7319fe3699f315b99e01f433ef2aa234",
+    "primaryResultStoreSha256": "92343fb369fea68b2544b654151c5c43a935940580b14afbe8eefb3844f72a54",
+    "secondaryTotalReturn": 1.1342962298106998,
+    "secondaryTradeCount": 19404,
+    "secondaryCanonicalSha256": "0dbd3fad624097c673c4a5ec2f545f95e9c21d1d5337bb2b48ffeb22b16cb2b9",
+    "secondaryResultStoreSha256": "416d2f87241fb4c6b917f6aeecb588f82f6e7d51a103f4c53a74d11971f16839",
+    "resultConsistent": true,
+    "terminalAuditStatus": "clean"
+  },
+  "profile": {
+    "allThreadRunId": "btr_1788549525151_3404548_13",
+    "allThreadRunEngineSeconds": 4.957,
+    "trimMatchesPercent": 2.0,
+    "typedBaselineSingleWorkerProfileTrimMatchesPercent": 2.85,
+    "comparisonLimited": true,
+    "reason": "the two profiles used different thread attachment sets and cannot establish an end-to-end speedup"
+  },
+  "remoteArtifacts": [
+    "/srv/fidc/canonical/run/fidc-private/evidence/cached-symbol-board-primary-20260905.json",
+    "/srv/fidc/canonical/run/fidc-private/evidence/cached-symbol-board-secondary-20260905.json",
+    "/srv/fidc/canonical/run/fidc-private/evidence/cached-symbol-board-rollback-primary-20260905.json",
+    "/srv/fidc/canonical/run/fidc-private/evidence/cached-symbol-board-all-threads-profile-20260905/perf.data"
+  ],
+  "acceptance": {
+    "status": "rejected_and_removed",
+    "reason": "the candidate preserved correctness but did not improve both five-year strategies, and the later rollback batch was too heavily contended to overturn the cross-strategy regression"
+  }
+}