refactor: rewrite zc in Rust

.github/workflows/ci.yml

@@ -10,19 +10,34 @@ permissions:
 
 jobs:
   lint:
-    name: shellcheck + syntax
+    name: fmt + clippy
     runs-on: ubuntu-latest
     steps:
       - uses: actions/checkout@de0fac2e4500dabe0009e67214ff5f5447ce83dd # v6.0.2
         with:
           persist-credentials: false
-      # shellcheck is preinstalled on ubuntu-latest runners.
+      - name: rustfmt
+        run: cargo fmt --all -- --check
+      - name: clippy
+        run: cargo clippy --all-targets --all-features -- -D warnings
+      - name: unit tests
+        run: cargo test --locked --all-features
       - name: shellcheck
-        run: shellcheck -S warning zc tests/run.sh
+        run: shellcheck -S warning tests/run.sh
       - name: bash syntax
-        run: |
-          bash -n zc
-          bash -n tests/run.sh
+        run: bash -n tests/run.sh
+
+  msrv:
+    name: MSRV build
+    runs-on: ubuntu-latest
+    steps:
+      - uses: actions/checkout@de0fac2e4500dabe0009e67214ff5f5447ce83dd # v6.0.2
+        with:
+          persist-credentials: false
+      - name: Install the declared MSRV toolchain
+        run: rustup toolchain install 1.82 --profile minimal --no-self-update
+      - name: check
+        run: cargo +1.82 check --locked --all-features --all-targets
 
   test:
     name: integration tests
@@ -55,5 +70,9 @@ jobs:
         with:
           baseline: ${{ steps.fixture.outputs.baseline }}
           working-directory: action-fixture
+      - name: Build zc
+        run: cargo build --release --locked
       - name: Run integration tests
+        env:
+          ZC: ${{ github.workspace }}/target/release/zc
         run: tests/run.sh

.gitignore

@@ -0,0 +1 @@
+/target

Cargo.toml

@@ -0,0 +1,22 @@
+[package]
+name = "zc"
+version = "0.3.0"
+edition = "2021"
+rust-version = "1.82"
+description = "Detect public API and dependency changes across all workspace crates between two git refs."
+license = "MIT OR Apache-2.0"
+repository = "https://github.com/ZcashFoundation/zc"
+
+[[bin]]
+name = "zc"
+path = "src/main.rs"
+
+[dependencies]
+hex = "0.4"
+regex = "1"
+serde = { version = "1", features = ["derive"] }
+serde_json = "1"
+sha1 = "0.10"
+
+[profile.release]
+debug = false

README.md

@@ -81,23 +81,18 @@ cargo install cargo-public-api --version 0.52.0 --locked
 rustup toolchain install nightly-2026-07-18 --profile minimal
 ```
 
-Then get `zc` itself — it's a single Bash script. Install it onto your `PATH`:
+Then install `zc` itself, a single Rust binary:
 
 ```sh
-curl -fsSL https://raw.githubusercontent.com/ZcashFoundation/zc/v0.3.0/zc -o ~/.local/bin/zc
-chmod +x ~/.local/bin/zc
+cargo install --git https://github.com/ZcashFoundation/zc --tag v0.3.0 --locked
 ```
 
-…or run a one-off without installing:
+…or from a checkout:
 
 ```sh
-curl -fsSL https://raw.githubusercontent.com/ZcashFoundation/zc/v0.3.0/zc | bash -s -- main
+cargo install --path . --locked
 ```
 
-> When run via `curl … | bash`, `--help` shows only a short usage (the script
-> can't re-read its own source from a pipe); install it to a file for the full
-> reference.
-
 ## Usage
 
 ```sh
@@ -242,9 +237,7 @@ Then ask Claude to "produce the changelog for PR #N" (or invoke `/zc N`).
 
 ## Requirements
 
-- Bash 4+ (associative arrays). On macOS, zc tries to re-exec with `bash` from PATH, `/opt/homebrew/bin/bash`, or `/usr/local/bin/bash` before failing. Install it with `brew install bash`.
 - [`cargo-public-api`](https://github.com/cargo-public-api/cargo-public-api)
-- `jq`
 - a `nightly` toolchain for rustdoc JSON builds
 
 ## Exit codes

action.yml

@@ -30,13 +30,9 @@ inputs:
 runs:
   using: composite
   steps:
-    - name: Check system dependencies
+    - name: Build zc
       shell: bash
-      run: |
-        if ! command -v jq >/dev/null 2>&1; then
-          echo "::error title=Missing zc dependency::Install jq on the runner before using this action."
-          exit 64
-        fi
+      run: cargo install --path "$GITHUB_ACTION_PATH" --locked --root "$RUNNER_TEMP/zc-bin"
 
     - name: Install the Rust nightly used by zc
       shell: bash
@@ -90,4 +86,4 @@ runs:
           arguments+=("$INPUT_HEAD")
         fi
 
-        "$GITHUB_ACTION_PATH/zc" "${arguments[@]}"
+        "$RUNNER_TEMP/zc-bin/bin/zc" "${arguments[@]}"

skills/zc/SKILL.md

@@ -13,7 +13,7 @@ description: >-
 Run `zc --changelog`, curate its draft into
 [librustzcash](https://github.com/zcash/librustzcash)-style entries, and
 **write them into the repo's `CHANGELOG.md` files**. Needs `zc` on `PATH` (plus
-its prereqs: `cargo-public-api`, `jq`, a nightly toolchain).
+its prereqs: `cargo-public-api`, a nightly toolchain).
 
 ## Quick start