ci: broaden macOS runners, add Linux runner toggle

- Remove `studio` label pin from macOS jobs in test.yml and release.yml,
  allowing jobs to schedule on any [macOS, ARM64] self-hosted runner
- Add `linux-runner` workflow_dispatch input to both workflows with
  fallback to vanilla `blacksmith-4vcpu-ubuntu-2404` for safe rollback
- Keep deno-lint and vitest on vanilla runner (no migration without
  measured benefit)
- Update docs/builds.md runner references
- Windows CI unchanged

Co-Authored-By: Claude Opus 4.6 (1M context) <noreply@anthropic.com>

Author: pythoninthegrass

.github/workflows/release.yml

@@ -13,6 +13,14 @@ on:
           - macos
           - linux
           - windows
+      linux-runner:
+        description: 'Linux runner label (custom image or vanilla fallback)'
+        required: false
+        default: 'blacksmith-4vcpu-ubuntu-2404'
+        type: choice
+        options:
+          - blacksmith-4vcpu-ubuntu-2404
+          - blacksmith-4vcpu-ubuntu-2404-mt
   release:
     types: [published]
 
@@ -32,7 +40,7 @@ jobs:
     if: >
       github.event_name == 'release' ||
       inputs.platform == 'all' || inputs.platform == 'macos' || inputs.platform == ''
-    runs-on: [macOS, ARM64, studio]
+    runs-on: [macOS, ARM64]
     timeout-minutes: 30
 
     steps:
@@ -114,7 +122,7 @@ jobs:
     if: >
       github.event_name == 'release' ||
       inputs.platform == 'all' || inputs.platform == 'linux' || inputs.platform == ''
-    runs-on: blacksmith-4vcpu-ubuntu-2404
+    runs-on: ${{ inputs.linux-runner || 'blacksmith-4vcpu-ubuntu-2404' }}
     timeout-minutes: 30
 
     steps:

.github/workflows/test.yml

@@ -2,6 +2,15 @@ name: Test
 
 on:
   workflow_dispatch:
+    inputs:
+      linux-runner:
+        description: 'Linux runner label (custom image or vanilla fallback)'
+        required: false
+        default: 'blacksmith-4vcpu-ubuntu-2404'
+        type: choice
+        options:
+          - blacksmith-4vcpu-ubuntu-2404
+          - blacksmith-4vcpu-ubuntu-2404-mt
   pull_request:
     paths:
       - 'crates/**'
@@ -28,7 +37,7 @@ env:
 jobs:
   rust:
     name: Rust Lint, Format, and Test
-    runs-on: [macOS, ARM64, studio]
+    runs-on: [macOS, ARM64]
     timeout-minutes: 20
     env:
       CARGO_INCREMENTAL: 1
@@ -100,10 +109,10 @@ jobs:
       matrix:
         include:
           - platform: macos
-            os: [macOS, ARM64, studio]
+            os: [macOS, ARM64]
             target: aarch64-apple-darwin
           - platform: linux
-            os: blacksmith-4vcpu-ubuntu-2404
+            os: ${{ inputs.linux-runner || 'blacksmith-4vcpu-ubuntu-2404' }}
             target: x86_64-unknown-linux-gnu
           - platform: windows
             os: [self-hosted, Windows, X64]

docs/builds.md

@@ -7,7 +7,7 @@ Build configuration, performance tuning, signing, and distribution for mt.
 | Platform | Architecture | Runner | Bundle |
 | ---------- | ------------- | -------- | -------- |
 | macOS | ARM64 | Self-hosted `[macOS, ARM64]` | `.app`, `.dmg` |
-| Linux | amd64 | `ubuntu-latest` (CI) or Docker (`Dockerfile.linux-amd64`) | `.deb` |
+| Linux | amd64 | Blacksmith `blacksmith-4vcpu-ubuntu-2404` (configurable, see [CI Runner Policy](#ci-runner-policy)) | `.deb` |
 | Windows | x64 | Self-hosted `[self-hosted, Windows, X64]` | `.exe` (NSIS) |
 
 ## Taskfile Commands
@@ -512,7 +512,7 @@ Runs on a self-hosted `[macOS, ARM64]` runner:
 
 ### `build-linux-amd64` — Linux amd64
 
-Runs on `ubuntu-latest`:
+Runs on a configurable Blacksmith runner (default: `blacksmith-4vcpu-ubuntu-2404`, selectable via `linux-runner` workflow input):
 
 1. Sets up the Tauri build environment via the shared composite action
 2. Builds with `tauri-action` targeting `x86_64-unknown-linux-gnu --bundles deb`