feat(zig): pin zig 0.15.2 via mise and wire taskfile + CI job (#47)

* feat(zig): pin zig 0.15.2 via mise and wire taskfile + CI job

Add a mise-managed Zig toolchain for the sidecar core. zig is resolved
with `mise which zig --tool zig@<pinned>` instead of PATH, since PATH may
hold an IDE-bundled zig or a mise default for another version.

- .tool-versions: pin zig 0.15.2
- taskfiles/zig.yml: format, lint, test, build, clean and a TARGET-driven
  cross-compile task, each behind an internal _check-zig-version task that
  fails with the expected/found version and the mise fix
- taskfile.yml: include zig and call zig:lint/format/test from the root
  aggregate tasks (root build stays Tauri-only)
- zig-core/: placeholder executable plus one unit test; the vendored
  SQLite binding lands in TASK-355.2
- .github/workflows/test.yml: standalone zig job on a Blacksmith Linux
  runner, caching zig-core/.zig-cache and zig-core/zig-out, absent from
  every other job's needs so it cannot extend the critical path

* fix(ci): use go-task/setup-task to match repo convention

The zig CI job used arduino/setup-task, inconsistent with the
go-task/setup-task action already relied on elsewhere in this repo
(.github/actions/setup-tauri-build/action.yml).

Author: pythoninthegrass

.github/workflows/test.yml

@@ -71,6 +71,48 @@ jobs:
       - name: Run Deno lint
         run: deno lint
 
+  # Independent of the rust job and intentionally absent from build/playwright
+  # needs: so Zig work cannot extend the critical path.
+  zig:
+    name: Zig Lint, Test, and Build
+    runs-on: blacksmith-4vcpu-ubuntu-2404
+    timeout-minutes: 10
+
+    steps:
+      - uses: actions/checkout@v6
+
+      - name: Read pinned Zig toolchain from .tool-versions
+        id: zig-version
+        shell: bash
+        run: |
+          version=$(grep '^zig ' .tool-versions | awk '{print $2}')
+          echo "toolchain=${version}" >> "$GITHUB_OUTPUT"
+
+      - name: Restore Zig build cache
+        uses: actions/cache@v4
+        with:
+          path: |
+            zig-core/.zig-cache
+            zig-core/zig-out
+          key: zig-build-${{ runner.os }}-${{ steps.zig-version.outputs.toolchain }}-${{ hashFiles('zig-core/build.zig', 'zig-core/build.zig.zon', 'zig-core/src/**/*.zig', '.tool-versions') }}
+
+      - name: Install Zig
+        uses: mlugg/setup-zig@v2
+        with:
+          version: ${{ steps.zig-version.outputs.toolchain }}
+
+      - name: Install Task
+        uses: go-task/setup-task@v1
+
+      - name: Zig format check
+        run: task zig:lint
+
+      - name: Zig tests
+        run: task zig:test
+
+      - name: Zig build
+        run: task zig:build
+
   build:
     name: Build (${{ matrix.platform }})
     # Gate on lint/format/test jobs so builds don't burn CI minutes

.tool-versions

@@ -9,3 +9,4 @@ prek           0.3.2
 ruff           0.12.11
 uv             0.9.24
 hadolint       2.14.0
+zig            0.15.2

backlog/tasks/task-355.1 - Zig-toolchain-Taskfile-integration-and-CI-job.md

@@ -1,7 +1,7 @@
 ---
 id: TASK-355.1
 title: 'Zig toolchain, Taskfile integration, and CI job'
-status: To Do
+status: In Progress
 assignee: []
 created_date: '2026-09-11 00:38'
 labels: []
@@ -19,10 +19,29 @@ The Zig toolchain must be reproducibly available to both local developers and CI
 
 ## Acceptance Criteria
 <!-- AC:BEGIN -->
-- [ ] #1 zig 0.15.2 is pinned in .tool-versions
-- [ ] #2 taskfiles/zig.yml provides format, lint, test, build, and cross-compile tasks following the structure of taskfiles/cargo.yml
-- [ ] #3 A missing or version-mismatched zig installation fails with an actionable error message rather than silently using the wrong binary
-- [ ] #4 task lint, task format, and task test invoke the Zig equivalents alongside the existing Rust and Deno ones
-- [ ] #5 A new zig CI job runs on a Blacksmith Linux runner in parallel with the existing rust job and does not extend the critical path
+- [x] #1 zig 0.15.2 is pinned in .tool-versions
+- [x] #2 taskfiles/zig.yml provides format, lint, test, build, and cross-compile tasks following the structure of taskfiles/cargo.yml
+- [x] #3 A missing or version-mismatched zig installation fails with an actionable error message rather than silently using the wrong binary
+- [x] #4 task lint, task format, and task test invoke the Zig equivalents alongside the existing Rust and Deno ones
+- [x] #5 A new zig CI job runs on a Blacksmith Linux runner in parallel with the existing rust job and does not extend the critical path
 - [ ] #6 Both a cold-cache and a warm-cache run of the zig job are measured and the timings recorded on this task
 <!-- AC:END -->
+
+## Plan
+<!-- SECTION:PLAN:BEGIN -->
+See PROMPT.md decisions on the branch: `zig-core/` placeholder executable (no SQLite/HTTP — that is TASK-355.2), zig resolved through mise against the pinned version rather than PATH, and a standalone `zig` CI job that no other job depends on.
+<!-- SECTION:PLAN:END -->
+
+## Notes
+<!-- SECTION:NOTES:BEGIN -->
+### Local verification (2026-09-11)
+
+`mise install zig` -> 0.15.2, then all green against the placeholder `zig-core/`:
+`task zig:format`, `task zig:lint`, `task zig:test` (1/1 tests passed), `task zig:build`, plus `task zig:cross-compile TARGET=aarch64-macos|x86_64-macos|x86_64-linux|x86_64-windows`. `task --list` shows the six `zig:*` tasks, and root `task format` / `task lint` / `task test` now run the zig step last (the Vitest step in root `task test` fails on 17 pre-existing frontend failures in `context-menu-favorites`, `go-to-album`, `go-to-artist` and `library.store` tests — untouched by this task).
+
+AC#3 was exercised by hand: a pinned version that is not installed, a resolved binary reporting a different version, and `mise` absent from PATH each produce their own error naming the expected version, what was found, and the `mise install zig` fix.
+
+### AC#6 still open — needs a push
+
+Cold/warm cache timings cannot be measured from this unpushed worktree. The job caches `zig-core/.zig-cache` and `zig-core/zig-out` under a key of runner OS + pinned version + `hashFiles(build.zig, build.zig.zon, src/**/*.zig, .tool-versions)`, so the measurement is ready to take: push this branch, run the `zig` job twice (first run cold, second warm with unchanged inputs), and record both durations from the Actions UI here.
+<!-- SECTION:NOTES:END -->

taskfile.yml

@@ -30,6 +30,8 @@ includes:
     taskfile: ./taskfiles/deno.yml
   cargo:
     taskfile: ./taskfiles/cargo.yml
+  zig:
+    taskfile: ./taskfiles/zig.yml
   tauri:
     taskfile: ./taskfiles/tauri.yml
   ci:
@@ -51,18 +53,21 @@ tasks:
     cmds:
       - task: cargo:lint
       - task: deno:lint
+      - task: zig:lint
 
   format:
     desc: "Run formatters"
     cmds:
       - task: cargo:format
       - task: deno:format
+      - task: zig:format
 
   test:
-    desc: "Run tests (Rust + Frontend)"
+    desc: "Run tests (Rust + Frontend + Zig)"
     cmds:
       - task: cargo:test
       - task: deno:test
+      - task: zig:test
 
   test:e2e:
     desc: "Run Playwright E2E tests"

taskfiles/zig.yml

@@ -0,0 +1,107 @@
+version: "3.0"
+
+set: ['e', 'u', 'pipefail']
+shopt: ['globstar']
+
+vars:
+  ZIG_CORE_DIR: "{{.ROOT_DIR}}/zig-core"
+  ZIG_OUT_DIR: "{{.ZIG_CORE_DIR}}/zig-out"
+  ZIG_CACHE_DIR: "{{.ZIG_CORE_DIR}}/.zig-cache"
+  PINNED_ZIG:
+    sh: grep '^zig ' {{.ROOT_DIR}}/.tool-versions 2>/dev/null | awk '{print $2}' || true
+  # Resolved through mise against the pinned version rather than PATH, which may
+  # hold an IDE-bundled zig or a mise default for a different version.
+  ZIG:
+    sh: | 
+      pin="{{.PINNED_ZIG}}"
+      if [ -n "$pin" ] && command -v mise &> /dev/null; then
+        mise which zig --tool "zig@$pin" 2>/dev/null || true
+      fi
+  # Explicit target triple for the cross-compile task, e.g. TARGET=aarch64-macos
+  TARGET: '{{.TARGET | default ""}}'
+
+tasks:
+  _check-zig-version:
+    internal: true
+    desc: "Verify the pinned zig resolves and matches .tool-versions"
+    cmds:
+      - |
+        mise_bin="{{.ZIG}}"
+        if [ ! -x "$mise_bin" ]; then
+          if ! command -v mise &> /dev/null; then
+            echo "error: zig {{.PINNED_ZIG}} not found and mise is not on PATH." >&2
+            echo "  Expected: {{.PINNED_ZIG}} (pinned in .tool-versions)" >&2
+            echo "  Fix: install mise (https://mise.jdx.dev), then run: mise install zig" >&2
+            exit 1
+          fi
+          echo "error: zig {{.PINNED_ZIG}} (pinned in .tool-versions) is not installed." >&2
+          echo "  Fix: mise install zig" >&2
+          exit 1
+        fi
+        found=$("$mise_bin" version 2>/dev/null)
+        if [ "$found" != "{{.PINNED_ZIG}}" ]; then
+          echo "error: zig version mismatch." >&2
+          echo "  Expected: {{.PINNED_ZIG}} (pinned in .tool-versions)" >&2
+          echo "  Found:    ${found:-unknown} ($mise_bin)" >&2
+          echo "  Fix: mise install zig@{{.PINNED_ZIG}}" >&2
+          exit 1
+        fi
+        echo "zig $found -> $mise_bin"
+
+  format:
+    desc: "Format Zig source files"
+    deps: [_check-zig-version]
+    cmds:
+      - '{{.ZIG}} fmt {{.ZIG_CORE_DIR}}/'
+
+  lint:
+    desc: "Check Zig formatting without making changes"
+    deps: [_check-zig-version]
+    cmds:
+      - '{{.ZIG}} fmt --check {{.ZIG_CORE_DIR}}/'
+
+  test:
+    desc: "Run Zig unit tests"
+    deps: [_check-zig-version]
+    cmds:
+      - cd {{.ZIG_CORE_DIR}} && {{.ZIG}} build test
+
+  build:
+    desc: "Build zig-core sidecar (debug)"
+    deps: [_check-zig-version]
+    cmds:
+      - cd {{.ZIG_CORE_DIR}} && {{.ZIG}} build
+    sources:
+      - "{{.ZIG_CORE_DIR}}/src/**/*.zig"
+      - "{{.ZIG_CORE_DIR}}/build.zig"
+      - "{{.ZIG_CORE_DIR}}/build.zig.zon"
+    generates:
+      - "{{.ZIG_OUT_DIR}}/bin/mt-zig-core"
+
+  cross-compile:
+    desc: "Cross-compile zig-core for a Zig target triple (TARGET required)"
+    summary: |
+      Cross-compile the zig-core sidecar for an explicit Zig target triple.
+
+        task zig:cross-compile TARGET=aarch64-macos
+        task zig:cross-compile TARGET=x86_64-macos
+        task zig:cross-compile TARGET=x86_64-linux
+        task zig:cross-compile TARGET=x86_64-windows
+    deps: [_check-zig-version]
+    preconditions:
+      - sh: test -n "{{.TARGET}}"
+        msg: |
+          TARGET is not set. Pass a Zig target triple, e.g.:
+            task zig:cross-compile TARGET=aarch64-macos
+            task zig:cross-compile TARGET=x86_64-macos
+            task zig:cross-compile TARGET=x86_64-linux
+            task zig:cross-compile TARGET=x86_64-windows
+    cmds:
+      - cd {{.ZIG_CORE_DIR}} && {{.ZIG}} build -Dtarget={{.TARGET}}
+
+  clean:
+    desc: "Clean Zig build artifacts"
+    cmds:
+      - rm -rf {{.ZIG_OUT_DIR}}
+      - rm -rf {{.ZIG_CACHE_DIR}}
+    silent: true

zig-core/build.zig

@@ -0,0 +1,37 @@
+const std = @import("std");
+
+pub fn build(b: *std.Build) void {
+    const target = b.standardTargetOptions(.{});
+    const optimize = b.standardOptimizeOption(.{});
+
+    // Sidecar executable. Metadata parsing stays in crates/mt-core until the
+    // Zig core is vendored in (TASK-355.2).
+    const exe = b.addExecutable(.{
+        .name = "mt-zig-core",
+        .root_module = b.createModule(.{
+            .root_source_file = b.path("src/main.zig"),
+            .target = target,
+            .optimize = optimize,
+        }),
+    });
+
+    b.installArtifact(exe);
+
+    const run_cmd = b.addRunArtifact(exe);
+    run_cmd.step.dependOn(b.getInstallStep());
+    if (b.args) |args| run_cmd.addArgs(args);
+    const run_step = b.step("run", "Run the sidecar");
+    run_step.dependOn(&run_cmd.step);
+
+    const exe_tests = b.addTest(.{
+        .root_module = b.createModule(.{
+            .root_source_file = b.path("src/main.zig"),
+            .target = target,
+            .optimize = optimize,
+        }),
+    });
+
+    const run_tests = b.addRunArtifact(exe_tests);
+    const test_step = b.step("test", "Run unit tests");
+    test_step.dependOn(&run_tests.step);
+}

zig-core/build.zig.zon

@@ -0,0 +1,11 @@
+.{
+    .name = .mt_zig_core,
+    .version = "0.0.0",
+    .fingerprint = 0x644b78534ae9e63e, // Changing this has security and trust implications.
+    .minimum_zig_version = "0.15.2",
+    .paths = .{
+        "build.zig",
+        "build.zig.zon",
+        "src",
+    },
+}

zig-core/src/main.zig

@@ -0,0 +1,10 @@
+const std = @import("std");
+
+pub fn main() !void {
+    // Prints to stderr, ignoring potential errors.
+    std.debug.print("mt-zig-core\n", .{});
+}
+
+test "sanity" {
+    try std.testing.expect(1 + 1 == 2);
+}