diff --git a/.github/workflows/ci-failure-fix.md b/.github/workflows/ci-failure-fix.md
index 28271b3472b499..21694c7daa752d 100644
--- a/.github/workflows/ci-failure-fix.md
+++ b/.github/workflows/ci-failure-fix.md
@@ -142,7 +142,7 @@ For each result, read the body + latest comments through the `github` MCP (NOT `
 
 ### Step 3 — Existing-artifact dedup (search live GitHub, every KBE)
 
-Before doing any analysis work, confirm nothing already handles this KBE. Use the `github` MCP search tools:
+Before doing any analysis work, confirm nothing already handles this KBE. GitHub's search tokenizer drops the leading `#`, so a bare `"#<kbe>"` phrase match is unreliable: build a `<kbe> -> [PRs]` map once per run by enumerating every `[ci-fix]` PR (`repo:dotnet/runtime is:pr in:title "[ci-fix]"` across `is:open`, `is:merged`, `is:closed closed:>=<today-30d>`) and parsing each `Linked KBE:` marker, then resolve checks 1–3 against that map. Use the `github` MCP search tools:
 
 1. **Open fix PR already exists** — `repo:dotnet/runtime is:pr is:open in:title "[ci-fix]" "#<kbe>"` OR body contains `Linked KBE: #<kbe>`. If found -> `-> skipped: open fix PR #<n> already exists`.
 2. **Merged fix PR exists** — `repo:dotnet/runtime is:pr is:merged "Linked KBE: #<kbe>"`. If found, the KBE is likely already fixed -> `-> skipped: fix PR #<n> already merged; KBE may be stale`.
@@ -178,7 +178,7 @@ Apply these fixer-specific bounds on top of the skill's guidance:
 
 | KBE pipeline / area | Fix policy |
 |---|---|
-| Mobile (ios/tvos/maccatalyst/android/wasm/wasi) | Small test/csproj/condition fixes in bounds are fair game. |
+| Mobile (ios/tvos/maccatalyst/android/wasm/wasi) | Small test/csproj/condition fixes in bounds are fair game. For trimming/AOT reflection failures, do **not** root a type in the test assembly itself via `ILLink.Descriptors.xml`/`TrimmerRootDescriptor` — test assemblies are rooted whole, so this is a no-op; only root a separate owning assembly confirmed from source, else loop in with a comment. |
 | JIT / GC / PGO stress (codegen) | JIT/GC product fixes are OUT of bounds for any PR — no safe diff is producible, so loop in JIT/GC owners with a comment. Workarounds in unrelated code (e.g. changing library buffer sizes or API call patterns to sidestep a codegen bug) are equally OUT of bounds — go straight to the loop-in comment instead of opening a workaround PR. |
 | `System.Net.*` | In bounds only if it satisfies Step 5.2. |
 | `Microsoft.Extensions.*` | In bounds only if it satisfies Step 5.2. |
diff --git a/.github/workflows/shared/create-kbe.instructions.md b/.github/workflows/shared/create-kbe.instructions.md
index d5c9f9fd99e9f9..86c895dca71862 100644
--- a/.github/workflows/shared/create-kbe.instructions.md
+++ b/.github/workflows/shared/create-kbe.instructions.md
@@ -118,6 +118,17 @@ it from the build metadata, not the queue time) against the issue's `closed_at`:
   predecessor `#<n>` in the body so the regression is explicit, mirroring the
   merged-fix-PR recurrence rule below.
 
+**Recurring signature.** Evaluate this check *before* acting on the post-close
+recurrence case above; when it applies, it takes precedence. First re-run the
+closed-candidate searches for the test-name stem with the look-back widened from
+`closed:>=<30-days-ago>` to `closed:>=<90-days-ago>` — the wider window is what
+lets a recurring signature surface at all. If that widened scan returns **two or
+more** closed `[ci-scan]` predecessors sharing the stem, treat it as a recurring
+signature, not a fresh regression: do **not** file — record `existing-kbe #<n>`
+against the most recently closed predecessor, even if the current build finished
+after that predecessor's `closed_at`. Fewer than two hits is not a recurring
+signature; fall back to the post-close recurrence rule above.
+
 <a id="search-area-team-tracker"></a>
 
 ## Search for an area-team tracker