chore(rust): pin toolchain to nightly-2026-08-20 for -Zmin-publish-age, drop Tier-3 build-std legs

.cargo/config.toml

@@ -1,10 +1,16 @@
 # Supply-chain soak for cargo's own dependency resolution — the same
 # soak-window rule the npm side applies via minimumReleaseAge /
 # min-release-age: crate versions younger than the window are skipped by
-# the resolver unless already in Cargo.lock. min-publish-age is an
-# [unstable] cargo feature, so these keys bite only under a nightly
-# toolchain; on perry's stable toolchain they are inert and the automated
-# window rides dependabot's cooldown (.github/dependabot.yml) instead.
+# the resolver unless already in Cargo.lock. min-publish-age is nightly-
+# only, which is why every workflow pins `dtolnay/rust-toolchain`'s
+# `toolchain:` input to a dated nightly (external-tools.json's `rust`
+# entry) instead of stable — this block is LIVE only on that pin.
+#
+# TEMPORARY: move to a stable pin once min-publish-age stabilizes —
+# targets Rust 1.100.0 (late September 2026), per
+# https://github.com/rust-lang/cargo/pull/17335 (open) and
+# https://github.com/rust-lang/cargo/issues/17009. Same condition
+# socket-wheelhouse's canonical rust-toolchain.toml is waiting on.
 # Managed by scripts/soak/soak.mts (`npm run soak` / `npm run soak:fix`).
 [unstable]
 min-publish-age = true

.github/workflows/auto-opt-app-patterns.yml

@@ -138,6 +138,8 @@ jobs:
       - name: Install Rust toolchain
         if: steps.relevance.outputs.run == 'true'
         uses: dtolnay/rust-toolchain@stable
+        with:
+          toolchain: 'nightly-2026-08-20'
       - uses: ./.github/actions/setup-llvm22
 
       - uses: Swatinem/rust-cache@v2

.github/workflows/benchmark.yml

@@ -48,6 +48,8 @@ jobs:
 
       - name: Install Rust toolchain
         uses: dtolnay/rust-toolchain@stable
+        with:
+          toolchain: 'nightly-2026-08-20'
       - uses: ./.github/actions/setup-llvm22
 
       - name: Cache cargo
@@ -270,6 +272,8 @@ jobs:
 
       - name: Install Rust toolchain
         uses: dtolnay/rust-toolchain@stable
+        with:
+          toolchain: 'nightly-2026-08-20'
       - uses: ./.github/actions/setup-llvm22
 
       - name: Cache cargo
@@ -368,6 +372,8 @@ jobs:
 
       - name: Install Rust toolchain
         uses: dtolnay/rust-toolchain@stable
+        with:
+          toolchain: 'nightly-2026-08-20'
       - uses: ./.github/actions/setup-llvm22
 
       - name: Measure clean-build time

.github/workflows/container-tests.yml

@@ -97,6 +97,8 @@ jobs:
 
       - name: Install Rust toolchain
         uses: dtolnay/rust-toolchain@stable
+        with:
+          toolchain: 'nightly-2026-08-20'
       - uses: ./.github/actions/setup-llvm22
 
       - name: Cache cargo registry
@@ -171,6 +173,8 @@ jobs:
 
       - name: Install Rust toolchain
         uses: dtolnay/rust-toolchain@stable
+        with:
+          toolchain: 'nightly-2026-08-20'
       - uses: ./.github/actions/setup-llvm22
 
       - name: Cache cargo registry
@@ -213,6 +217,8 @@ jobs:
 
       - name: Install Rust toolchain
         uses: dtolnay/rust-toolchain@stable
+        with:
+          toolchain: 'nightly-2026-08-20'
       - uses: ./.github/actions/setup-llvm22
 
       - name: Cache cargo registry
@@ -257,6 +263,8 @@ jobs:
 
       - name: Install Rust toolchain
         uses: dtolnay/rust-toolchain@stable
+        with:
+          toolchain: 'nightly-2026-08-20'
       - uses: ./.github/actions/setup-llvm22
 
       - name: Cache cargo registry

.github/workflows/coverage.yml

@@ -37,6 +37,7 @@ jobs:
       - name: Install Rust toolchain
         uses: dtolnay/rust-toolchain@stable
         with:
+          toolchain: 'nightly-2026-08-20'
           components: llvm-tools-preview
       - uses: ./.github/actions/setup-llvm22
 

.github/workflows/eh-transport.yml

@@ -116,6 +116,8 @@ jobs:
 
       - name: Install Rust toolchain
         uses: dtolnay/rust-toolchain@stable
+        with:
+          toolchain: 'nightly-2026-08-20'
       - uses: ./.github/actions/setup-llvm22
 
       - name: Setup Node.js

.github/workflows/ext-link.yml

@@ -114,6 +114,8 @@ jobs:
       - name: Install Rust toolchain
         if: steps.scope.outputs.pkgs != ''
         uses: dtolnay/rust-toolchain@stable
+        with:
+          toolchain: 'nightly-2026-08-20'
       - if: steps.scope.outputs.pkgs != ''
         uses: ./.github/actions/setup-llvm22
 

.github/workflows/feature-matrix.yml

@@ -39,6 +39,8 @@ jobs:
 
       - name: Install Rust toolchain
         uses: dtolnay/rust-toolchain@stable
+        with:
+          toolchain: 'nightly-2026-08-20'
       - uses: ./.github/actions/setup-llvm22
 
       - uses: Swatinem/rust-cache@v2

.github/workflows/gc-moving-witnesses.yml

@@ -225,6 +225,8 @@ jobs:
       - name: Install Rust toolchain
         if: steps.relevance.outputs.run == 'true'
         uses: dtolnay/rust-toolchain@stable
+        with:
+          toolchain: 'nightly-2026-08-20'
       - uses: ./.github/actions/setup-llvm22
 
       - uses: Swatinem/rust-cache@v2

.github/workflows/gc-native-roots.yml

@@ -278,6 +278,8 @@ jobs:
         with:
           node-version-file: .node-version
       - uses: dtolnay/rust-toolchain@stable
+        with:
+          toolchain: 'nightly-2026-08-20'
       - uses: ./.github/actions/setup-llvm22
       - uses: Swatinem/rust-cache@v2
         with:

.github/workflows/gc-parse-churn-gate.yml

@@ -182,6 +182,8 @@ jobs:
       - name: Install Rust toolchain
         if: steps.relevance.outputs.run == 'true'
         uses: dtolnay/rust-toolchain@stable
+        with:
+          toolchain: 'nightly-2026-08-20'
       - uses: ./.github/actions/setup-llvm22
         if: steps.relevance.outputs.run == 'true'
 

.github/workflows/gc-ptr-shape-off-witness.yml

@@ -169,6 +169,8 @@ jobs:
       - name: Install Rust toolchain
         if: steps.relevance.outputs.run == 'true'
         uses: dtolnay/rust-toolchain@stable
+        with:
+          toolchain: 'nightly-2026-08-20'
       - uses: ./.github/actions/setup-llvm22
         if: steps.relevance.outputs.run == 'true'
 

.github/workflows/gc-ratchet.yml

@@ -179,6 +179,8 @@ jobs:
       - name: Install Rust toolchain
         if: steps.relevance.outputs.run == 'true'
         uses: dtolnay/rust-toolchain@stable
+        with:
+          toolchain: 'nightly-2026-08-20'
       - uses: ./.github/actions/setup-llvm22
 
       - name: Cache cargo

.github/workflows/gc-root-dominance.yml

@@ -217,6 +217,8 @@ jobs:
 
       - name: Install Rust toolchain
         uses: dtolnay/rust-toolchain@stable
+        with:
+          toolchain: 'nightly-2026-08-20'
       - uses: ./.github/actions/setup-llvm22
 
       # ★ The dependency-scale corpus needs the dependency.
@@ -499,6 +501,8 @@ jobs:
 
       - name: Install Rust toolchain
         uses: dtolnay/rust-toolchain@stable
+        with:
+          toolchain: 'nightly-2026-08-20'
       # This also puts a matched LLVM 22 `opt` on disk and exports
       # LLVM_SYS_221_PREFIX, which is how the corpus script finds it. The
       # native corpus is `--trace llvm` output PLUS the production statepoint

.github/workflows/next-app-route.yml

@@ -40,6 +40,8 @@ jobs:
           persist-credentials: false
 
       - uses: dtolnay/rust-toolchain@stable
+        with:
+          toolchain: 'nightly-2026-08-20'
       - uses: ./.github/actions/setup-llvm22
 
       - uses: mozilla-actions/sccache-action@v0.0.11

.github/workflows/node-compat-matrix.yml

@@ -62,6 +62,8 @@ jobs:
 
       - name: Install Rust toolchain
         uses: dtolnay/rust-toolchain@stable
+        with:
+          toolchain: 'nightly-2026-08-20'
       - uses: ./.github/actions/setup-llvm22
 
       - name: Start sccache

.github/workflows/node-core-subset.yml

@@ -74,6 +74,8 @@ jobs:
 
       - name: Install Rust toolchain
         uses: dtolnay/rust-toolchain@stable
+        with:
+          toolchain: 'nightly-2026-08-20'
       - uses: ./.github/actions/setup-llvm22
 
       - uses: Swatinem/rust-cache@v2

.github/workflows/node-suite-guard.yml

@@ -50,6 +50,8 @@ jobs:
 
       - name: Install Rust toolchain
         uses: dtolnay/rust-toolchain@stable
+        with:
+          toolchain: 'nightly-2026-08-20'
       - uses: ./.github/actions/setup-llvm22
 
       - name: Start sccache

.github/workflows/npm-package-sweep.yml

@@ -45,6 +45,8 @@ jobs:
 
       - name: Install Rust toolchain
         uses: dtolnay/rust-toolchain@stable
+        with:
+          toolchain: 'nightly-2026-08-20'
       - uses: ./.github/actions/setup-llvm22
 
       - uses: Swatinem/rust-cache@v2