chore: add justfile with dev, CI, and release tasks

justfile

@@ -0,0 +1,118 @@
+# agentfiles — development task runner
+# Run `just` with no arguments to see available recipes.
+
+# ---------------------------------------------------------------------------
+# Settings
+# ---------------------------------------------------------------------------
+
+set dotenv-load := false
+
+# ---------------------------------------------------------------------------
+# Default
+# ---------------------------------------------------------------------------
+
+# List available recipes
+default:
+    @just --list
+
+# ---------------------------------------------------------------------------
+# Development
+# ---------------------------------------------------------------------------
+
+# Type-check without codegen (fast feedback loop)
+check:
+    cargo check
+
+# Format code
+fmt:
+    cargo fmt
+
+# Lint with clippy (warnings are errors, matching CI)
+lint:
+    cargo clippy -- -D warnings
+
+# Run all tests
+test:
+    cargo test
+
+# Build debug binary
+build:
+    cargo build
+
+# Run the binary (pass arguments after --)
+run *args:
+    cargo run -- {{ args }}
+
+# Remove build artifacts
+clean:
+    cargo clean
+
+# ---------------------------------------------------------------------------
+# CI
+# ---------------------------------------------------------------------------
+
+# Run the full CI suite locally (fmt-check, lint, test, build)
+ci:
+    cargo fmt -- --check
+    cargo clippy -- -D warnings
+    cargo test
+    cargo build
+
+# ---------------------------------------------------------------------------
+# Release
+# ---------------------------------------------------------------------------
+
+# Prepare a release: validate, run CI, bump version, commit, and tag
+[doc("Validate, run CI, bump version, commit, and tag (usage: just release X.Y.Z)")]
+release version:
+    #!/usr/bin/env bash
+    set -euo pipefail
+
+    version="{{ version }}"
+
+    # -- Validate semver format (X.Y.Z) --
+    if ! echo "$version" | grep -qE '^[0-9]+\.[0-9]+\.[0-9]+$'; then
+        echo "error: version must be semver (X.Y.Z), got: $version" >&2
+        exit 1
+    fi
+
+    # -- Guard: must be on main branch --
+    branch="$(git rev-parse --abbrev-ref HEAD)"
+    if [ "$branch" != "main" ]; then
+        echo "error: releases must be created from main, currently on: $branch" >&2
+        exit 1
+    fi
+
+    # -- Guard: working tree must be clean --
+    if ! git diff --quiet || ! git diff --cached --quiet; then
+        echo "error: working tree is dirty — commit or stash changes first" >&2
+        exit 1
+    fi
+
+    # -- Guard: tag must not already exist --
+    if git rev-parse "v${version}" >/dev/null 2>&1; then
+        echo "error: tag v${version} already exists" >&2
+        exit 1
+    fi
+
+    # -- Run full CI suite --
+    echo "Running CI checks..."
+    just ci
+
+    # -- Bump version in Cargo.toml --
+    echo "Bumping version to ${version}..."
+    sed -i.bak -E "s/^version = \"[^\"]+\"/version = \"${version}\"/" Cargo.toml
+    rm -f Cargo.toml.bak
+
+    # -- Regenerate Cargo.lock --
+    cargo check --quiet
+
+    # -- Commit and tag --
+    git add Cargo.toml Cargo.lock
+    git commit -m "release: v${version}"
+    git tag "v${version}"
+
+    echo ""
+    echo "Release v${version} prepared. To publish, run:"
+    echo ""
+    echo "  git push && git push --tags"