diff --git a/.console/log.md b/.console/log.md
index 05306f9b..39d17061 100644
--- a/.console/log.md
+++ b/.console/log.md
@@ -1,3 +1,38 @@
+## 2026-08-03 — fix(ci): pin the lint toolchain, ending a week of red CI on main
+
+CI has failed on `main` every day since at least 2026-07-29. Cause: both lint gates
+installed ruff **unpinned** while the repo pins `ruff==0.15.13`.
+
+- `ci.yml` — `pip install "ruff>=0.5"` floated to 0.16.1. `ruff check .` went from
+  clean to **1996 errors**.
+- `custodian-audit.yml` — `pip install ruff vulture ty`, same drift. The audit
+  reported **1222 findings** (the ruff group alone; vulture was clean in CI).
+
+None of them were real. `[tool.ruff.lint]` selects a deliberate rule set and its own
+comment records BLE001 and S110 as DROPPED — "too noisy across codebase, real
+legitimate uses". A newer ruff re-enables exactly those: of the 1222, BLE001 was 316
+and UP045 290. Verified locally on the same tree: ruff 0.16.1 → 1222, ruff 0.15.13 →
+`All checks passed!` on the full `ruff check .`, root files included.
+
+Both now install `-e ".[dev]"`, taking the version from
+`[project.optional-dependencies].dev` so there is one source of truth and no version
+literal in the workflows to drift again.
+
+The irony worth recording: `custodian-audit.yml` already carried a paragraph
+explaining that Custodian itself must be SHA-pinned because tracking `@main` once let
+an upstream change emit "a phantom finding fleet-wide". The very next line then
+installed that pinned auditor's *tools* unpinned, reproducing the same failure one
+level down. Pinning the auditor while floating what the auditor runs pins nothing.
+
+Also made the repo install non-best-effort. It was `pip install -e . || true`; on
+failure the adapters find no ruff, Custodian reports "not installed" and SKIPS it,
+and the gate passes vacuously — a green check that audited nothing, which is worse
+than a red one.
+
+Related, same root cause one layer up: Custodian's `find_tool()` preferred its own
+venv over the audited repo's, so a globally-installed `custodian-multi` reproduced
+this identically off-CI. Fixed in ProtocolWarden/Custodian#72.
+
 ## 2026-07-15 — feat(reviewer): ACTIVATE the council — populate guardrail_paths (§G1)
 
 The council's go-live. C1/C2/C3 all merged; `reviewer.council.guardrail_paths`
diff --git a/.github/workflows/ci.yml b/.github/workflows/ci.yml
index 6de94eb1..ab2b3b9a 100644
--- a/.github/workflows/ci.yml
+++ b/.github/workflows/ci.yml
@@ -20,7 +20,16 @@ jobs:
         with:
           python-version: "3.11"
       - name: Install ruff
-        run: pip install "ruff>=0.5"
+        # Install the repo's own pinned toolchain rather than `ruff>=0.5`. A lint
+        # gate has to run the version the config was written against: `[tool.ruff]`
+        # here selects a deliberate rule set (BLE001 and S110 are explicitly
+        # DROPPED as too noisy, per the comment in pyproject), and a newer ruff
+        # re-enables rules that config never opted into. `ruff>=0.5` floated up to
+        # 0.16.1 and this job went from clean to 1996 errors — every one of them
+        # phantom — red-failing CI on main daily from ~2026-07-29. Taking the pin
+        # from [project.optional-dependencies].dev keeps one source of truth; do
+        # not reintroduce a version literal here.
+        run: pip install -e ".[dev]"
       - name: Run ruff
         run: ruff check .
 
diff --git a/.github/workflows/custodian-audit.yml b/.github/workflows/custodian-audit.yml
index f6b742ef..04ec4842 100644
--- a/.github/workflows/custodian-audit.yml
+++ b/.github/workflows/custodian-audit.yml
@@ -26,13 +26,20 @@ jobs:
         run: |
           python -m pip install --upgrade pip
           pip install "custodian[tools] @ git+https://github.com/ProtocolWarden/Custodian.git@d6ba8ab245c6f4e79e9f8fffd4e4221bfaf266e8"
-          pip install ruff vulture ty
+          pip install vulture
 
-      - name: Install repo (best-effort, for adapter passes)
-        run: |
-          if [ -f pyproject.toml ]; then
-            pip install -e . || true
-          fi
+      - name: Install repo and its pinned lint toolchain
+        # `.[dev]` (not plain `.`) so the adapters run OC's OWN pinned ruff/ty.
+        # The reproducibility argument in the step above applies one level down:
+        # pinning Custodian while installing `ruff` unpinned just moves the moving
+        # part. It floated to 0.16.1 and this gate reported 1222 findings against a
+        # tree the pinned ruff (0.15.13) calls clean — the same phantom-finding
+        # failure the Custodian pin was added to prevent.
+        #
+        # NOT best-effort (`|| true`) any more: a failed install left the adapters
+        # with no ruff at all, which Custodian reports as "not installed" and skips.
+        # The gate then passes vacuously — worse than failing, because it looks green.
+        run: pip install -e ".[dev]"
 
       - name: Materialize boundary artifact file
         # Decode the boundary disclosure artifact from the base64 CONTENT secret