diff --git a/.github/workflows/fast-checks.yaml b/.github/workflows/fast-checks.yaml
index 714529a9..e92812ea 100644
--- a/.github/workflows/fast-checks.yaml
+++ b/.github/workflows/fast-checks.yaml
@@ -10,19 +10,11 @@
 #       Every push to develop and every pull request. No gate, so the run is
 #       exactly what a maintainer sees locally: contracts, validation, wiring,
 #       the product surface, and the tight numerical unit guards that catch a
-#       shifted constant in one run. Budget: <= 15 min of tests in THIS job,
-#       which keeps the whole job near half its 30-minute timeout.
-#
-#       Read the budget off this job's own test phase. The tiering audit's
-#       "~90 s" is a different measurement -- an OPTIMIZED build on a developer
-#       machine -- and nothing this job prints can be compared against it.
-#       devtools::test() compiles a debug build (pkgbuild::compiler_flags(debug
-#       = TRUE) gives "-UNDEBUG -Wall -pedantic -g -O0"), and this job keeps it
-#       that way on purpose (see the extra-packages note below). Measured on
-#       identical content that build costs 2.38x, and this 2-core runner a
-#       further ~2.31x over one developer machine. So quote CI minutes here, or
-#       say which build a local number came from; a bare seconds figure is not
-#       comparable across the two and let this tier drift unnoticed once.
+#       shifted constant in one run. The budget is this job's own test phase:
+#       25 min on the October 2026 ubuntu-latest runner (run 39602904192),
+#       against timeout-minutes: 45. A local devtools::test() wall time is
+#       not comparable: it compiles a debug build (-O0) on a different
+#       machine. Measure from a run of this job that finished.
 #
 #   T1  nightly     .github/workflows/nightly-validation.yaml. Daily 03:00 UTC
 #       on develop, BGMS_RUN_SLOW_TESTS=true, <= 60 min, timeout 90.
@@ -48,9 +40,9 @@ on:
 
 jobs:
   fast-tests:
-    name: T0 every-run tier (~90 s of tests)
+    name: T0 every-run tier
     runs-on: ubuntu-latest
-    timeout-minutes: 30
+    timeout-minutes: 45
     env:
       GITHUB_PAT: ${{ secrets.GITHUB_TOKEN }}
       R_KEEP_PKG_SOURCE: yes
diff --git a/.github/workflows/nightly-validation.yaml b/.github/workflows/nightly-validation.yaml
index 065d0c8c..88d3fa88 100644
--- a/.github/workflows/nightly-validation.yaml
+++ b/.github/workflows/nightly-validation.yaml
@@ -8,7 +8,7 @@
 #
 #   T0  every run   local devtools::test() + .github/workflows/fast-checks.yaml
 #       Contracts, validation, wiring, the product surface, the tight numerical
-#       unit guards. No gate. Budget ~90 s.
+#       unit guards. No gate; budget stated in fast-checks.yaml.
 #
 #   T1  nightly     THIS FILE. Daily 03:00 UTC on develop.
 #       BGMS_RUN_SLOW_TESTS=true.
diff --git a/.github/workflows/weekly-certification.yaml b/.github/workflows/weekly-certification.yaml
index 52736b4b..f96d4d0c 100644
--- a/.github/workflows/weekly-certification.yaml
+++ b/.github/workflows/weekly-certification.yaml
@@ -8,7 +8,7 @@
 #
 #   T0  every run   local devtools::test() + .github/workflows/fast-checks.yaml
 #       Contracts, validation, wiring, the product surface, the tight numerical
-#       unit guards. No gate. Budget ~90 s.
+#       unit guards. No gate; budget stated in fast-checks.yaml.
 #
 #   T1  nightly     .github/workflows/nightly-validation.yaml. Daily 03:00 UTC.
 #       BGMS_RUN_SLOW_TESTS=true.
diff --git a/dev/review-2026-08/MAINTAINERS.md b/dev/review-2026-08/MAINTAINERS.md
index 299dae5e..6e3ad876 100644
--- a/dev/review-2026-08/MAINTAINERS.md
+++ b/dev/review-2026-08/MAINTAINERS.md
@@ -218,7 +218,7 @@ be T1. Budget is the tie-breaker, never the criterion.
 
 | Tier | Cadence | Content, by bug class | Budget | Gate |
 |---|---|---|---|---|
-| **T0** every run | local `devtools::test()`; every push to develop and every PR (`fast-checks.yaml`) | contracts, validation, wiring, unit guards, product surface | **≤ 15 min of tests** in the `fast-checks` job (`timeout-minutes: 30`) | none |
+| **T0** every run | local `devtools::test()`; every push to develop and every PR (`fast-checks.yaml`) | contracts, validation, wiring, unit guards, product surface | the `fast-checks` job's own test phase: 25 min on the October 2026 runner (`timeout-minutes: 45`) | none |
 | **T1** nightly heartbeat | daily 03:00 UTC on **develop** (`nightly-validation.yaml`) | curated calibration subset — graph-law and prior-chain identities, gauge detector, single surface-vs-gold cells, RB saturation, concordance smokes. "Does the settled math still hold tonight" | **≤ 60 min** on the 2-core runner; `timeout-minutes: 90` | `BGMS_RUN_SLOW_TESTS=true` |
 | **T2** weekly certification | Sunday 03:00 UTC on **develop** (`weekly-certification.yaml`) | the heavy Monte-Carlo machinery — SBC suites, full parameter-recovery sweeps, full NUTS-vs-MH condition grids, n = 2e6 MC channels, refit cross-validations (incl. the F-049 gate) | `timeout-minutes: 360` | `BGMS_RUN_CERTIFICATION=true` (the T2 workflow sets **both** vars, so a weekly run also carries T1) |
 
@@ -233,9 +233,11 @@ machine and landed 89.7 s; `devtools::test()` and every CI tier compile a
 *debug* build (`pkgbuild::compiler_flags(debug = TRUE)` is `-UNDEBUG -Wall
 -pedantic -g -O0`). Measured on byte-identical content the build is worth
 **2.38x**, and the 2-core runner a further **~2.31x** over one developer
-machine (`dev/review-2026-08/reports/40-t0-retier.md`). So the audit's 89.7 s
-and anything CI reports were never comparable, and T0 drifted for five weeks
-without the drift being visible to either number. The reference instrument is
+machine (`dev/review-2026-08/reports/40-t0-retier.md`). The audit's 89.7 s
+and anything CI reports are not comparable. The runner itself also moves:
+between the August and October 2026 images of `ubuntu-latest` every test file
+ran 1.4-2x slower (fast-checks runs 31265365814 and 39602904192), which took
+the every-run tier from 14 to 25 min of tests. The reference instrument is
 the `fast-checks` job's own test phase. When re-tiering, measure from a run
 that FINISHED, in that job, and quote minutes.
 
diff --git a/tests/testthat/helper-tiers.R b/tests/testthat/helper-tiers.R
index c3ee89a6..983e89b6 100644
--- a/tests/testthat/helper-tiers.R
+++ b/tests/testthat/helper-tiers.R
@@ -7,14 +7,10 @@
 #   T0  every run (local devtools::test(), and every push/PR)
 #       Contracts, validation, wiring, the product surface, and the tight
 #       numerical unit guards that catch a shifted constant in one run.
-#       No gate. Budget: <= 15 min of tests in the fast-checks job.
-#
-#       State which build any local number came from. devtools::test()
-#       compiles a debug build (-O0), the tiering audit measured an optimized
-#       one, and the two differ by 2.38x on identical content -- so the
-#       audit's "~90 s" cannot be compared with a devtools::test() wall time
-#       or with what CI prints. The fast-checks job is the reference
-#       instrument; see .github/workflows/fast-checks.yaml.
+#       No gate. Budget: the fast-checks job's own test phase (25 min on the
+#       October 2026 runner, timeout 45 min); see
+#       .github/workflows/fast-checks.yaml. A local devtools::test() wall
+#       time is a debug build on a different machine and is not comparable.
 #
 #       CRAN runs a SUBSET of T0: the heavy internal numerical guard files
 #       are excluded there via skip_heavy_guard_on_cran() below (maintainer