chore(commits): install commit-msg hook via make install-hooks

Makefile

@@ -75,10 +75,12 @@ help:
 	@echo "  check         - Run tests and lint"
 	@echo "  install       - Build and install to Go bin directory"
 	@echo "  calibrate-providers - Compare local Claude/Codex session usage for calibration"
-	@echo "  install-hooks  - Install git pre-commit hook"
+	@echo "  install-hooks  - Install git pre-commit and commit-msg hooks"
 	@echo "  help          - Show this help"
 
-# Install git pre-commit hook
+# Install git pre-commit and commit-msg hooks
 install-hooks:
 	@ln -sf ../../scripts/pre-commit.sh .git/hooks/pre-commit
+	@ln -sf ../../scripts/commit-msg.sh .git/hooks/commit-msg
 	@echo "✓ pre-commit hook installed (.git/hooks/pre-commit → scripts/pre-commit.sh)"
+	@echo "✓ commit-msg hook installed (.git/hooks/commit-msg → scripts/commit-msg.sh)"

README.md

@@ -106,16 +106,16 @@ selected provider, budget status, projects, and planned tasks. In interactive
 terminals you are prompted for confirmation; in non-TTY environments (cron,
 daemon, CI) confirmation is auto-skipped.
 
-| Flag | Default | Description |
-|------|---------|-------------|
-| `--dry-run` | `false` | Show preflight summary and exit without executing |
-| `--project`, `-p` | _(all configured)_ | Target a single project directory |
-| `--task`, `-t` | _(auto-select)_ | Run a specific task by name |
-| `--max-projects` | `1` | Max projects to process (ignored when `--project` is set) |
-| `--max-tasks` | `1` | Max tasks per project (ignored when `--task` is set) |
-| `--random-task` | `false` | Pick a random task from eligible tasks instead of the highest-scored one |
-| `--ignore-budget` | `false` | Bypass budget checks (use with caution) |
-| `--yes`, `-y` | `false` | Skip the confirmation prompt |
+| Flag              | Default            | Description                                                              |
+| ----------------- | ------------------ | ------------------------------------------------------------------------ |
+| `--dry-run`       | `false`            | Show preflight summary and exit without executing                        |
+| `--project`, `-p` | _(all configured)_ | Target a single project directory                                        |
+| `--task`, `-t`    | _(auto-select)_    | Run a specific task by name                                              |
+| `--max-projects`  | `1`                | Max projects to process (ignored when `--project` is set)                |
+| `--max-tasks`     | `1`                | Max tasks per project (ignored when `--task` is set)                     |
+| `--random-task`   | `false`            | Pick a random task from eligible tasks instead of the highest-scored one |
+| `--ignore-budget` | `false`            | Bypass budget checks (use with caution)                                  |
+| `--yes`, `-y`     | `false`            | Skip the confirmation prompt                                             |
 
 ```bash
 # Interactive run with preflight summary + confirmation prompt
@@ -141,6 +141,7 @@ nightshift run -p ./my-project -t lint-fix
 ```
 
 Other useful flags:
+
 - `nightshift status --today` to see today's activity summary
 - `nightshift daemon start --foreground` for debug
 - `--category` — filter tasks by category (pr, analysis, options, safe, map, emergency)
@@ -153,8 +154,9 @@ Other useful flags:
 ## Authentication (Subscriptions)
 
 Nightshift supports three AI providers:
+
 - **Claude Code** - Anthropic's Claude via local CLI
-- **Codex** - OpenAI's GPT via local CLI  
+- **Codex** - OpenAI's GPT via local CLI
 - **GitHub Copilot** - GitHub's Copilot via GitHub CLI
 
 ### Claude Code
@@ -258,19 +260,22 @@ Each task has a default cooldown interval to prevent the same task from running
 
 ## Development
 
-### Pre-commit hooks
+### Git hooks
 
-Install the git pre-commit hook to catch formatting and vet issues before pushing:
+Install the git hooks to catch formatting and vet issues and enforce Conventional Commits before pushing:
 
 ```bash
 make install-hooks
 ```
 
 This symlinks `scripts/pre-commit.sh` into `.git/hooks/pre-commit`. The hook runs:
+
 - **gofmt** — flags any staged `.go` files that need formatting
 - **go vet** — catches common correctness issues
 - **go build** — ensures the project compiles
 
+`make install-hooks` also installs a **commit-msg** hook (`scripts/commit-msg.sh` → `.git/hooks/commit-msg`) that enforces and rewrites commit messages into [Conventional Commits](docs/commit-messages.md) format via `nightshift commit normalize`. Every commit message is normalized automatically; see [docs/commit-messages.md](docs/commit-messages.md) for the supported types and rules.
+
 To bypass in a pinch: `git commit --no-verify`
 
 ## Uninstalling

cmd/nightshift/commands/commit.go

@@ -0,0 +1,88 @@
+package commands
+
+import (
+	"fmt"
+	"io"
+	"os"
+
+	"github.com/marcus/nightshift/internal/commits"
+	"github.com/spf13/cobra"
+)
+
+var commitCmd = &cobra.Command{
+	Use:   "commit",
+	Short: "Conventional Commits helpers",
+	Long: `Tools for working with Conventional Commits messages.
+
+Use "commit normalize" to validate and reformat a commit message so it
+follows the project's rules (type prefix, lowercase type, subject length,
+and wrapped body).`,
+}
+
+var commitNormalizeCmd = &cobra.Command{
+	Use:   "normalize [MESSAGE]",
+	Short: "Normalize a commit message to Conventional Commits format",
+	Long: `Validate and rewrite a commit message into canonical Conventional
+Commits form.
+
+The message is read from a positional argument, from a file passed via
+--file (typically .git/COMMIT_EDITMSG by a commit-msg hook), or from stdin
+when no argument and no --file are given.
+
+  nightshift commit normalize "feat: add login"
+  nightshift commit normalize --file .git/COMMIT_EDITMSG
+  git log -1 --pretty=%B | nightshift commit normalize
+
+Use --check to only validate without rewriting; the exit code is non-zero
+when the message does not conform.`,
+	Args: cobra.MaximumNArgs(1),
+	RunE: func(cmd *cobra.Command, args []string) error {
+		check, _ := cmd.Flags().GetBool("check")
+		file, _ := cmd.Flags().GetString("file")
+
+		raw, err := readCommitMessage(args, file)
+		if err != nil {
+			return err
+		}
+
+		normalized, err := commits.Normalize(raw)
+		if err != nil {
+			fmt.Fprintf(os.Stderr, "error: %v\n", err)
+			return err
+		}
+
+		if check {
+			fmt.Fprintln(os.Stdout, normalized)
+			return nil
+		}
+		fmt.Fprintln(os.Stdout, normalized)
+		return nil
+	},
+}
+
+func init() {
+	commitNormalizeCmd.Flags().BoolP("check", "c", false, "Only validate; do not rewrite")
+	commitNormalizeCmd.Flags().StringP("file", "f", "", "Read the message from this file (use by the commit-msg hook)")
+	commitCmd.AddCommand(commitNormalizeCmd)
+	rootCmd.AddCommand(commitCmd)
+}
+
+// readCommitMessage resolves the message source in order: positional arg,
+// --file, then stdin.
+func readCommitMessage(args []string, file string) (string, error) {
+	if len(args) == 1 {
+		return args[0], nil
+	}
+	if file != "" {
+		b, err := os.ReadFile(file)
+		if err != nil {
+			return "", fmt.Errorf("read %s: %w", file, err)
+		}
+		return string(b), nil
+	}
+	b, err := io.ReadAll(os.Stdin)
+	if err != nil {
+		return "", fmt.Errorf("read stdin: %w", err)
+	}
+	return string(b), nil
+}

docs/commit-messages.md

@@ -0,0 +1,47 @@
+# Commit Messages
+
+Nightshift uses [Conventional Commits](https://www.conventionalcommits.org/)
+for all commit messages. This keeps the history readable and lets tooling
+derive changelogs automatically.
+
+## Format
+
+```
+<type>(<scope>): <subject>
+
+<body>
+```
+
+- **type** — one of `feat`, `fix`, `docs`, `style`, `refactor`, `test`,
+  `chore`, `perf`, `build`, `ci`.
+- **scope** — optional, e.g. `fix(api): ...`.
+- **subject** — lowercase, imperative mood, no trailing period, max 72 chars.
+- **body** — optional, wrapped at 72 columns, separated from the subject by a
+  blank line.
+
+## The `commit normalize` command
+
+Validate and reformat a message:
+
+```sh
+nightshift commit normalize "feat: add login screen"
+nightshift commit normalize --file .git/COMMIT_EDITMSG
+git log -1 --pretty=%B | nightshift commit normalize
+```
+
+Add `--check` to validate only. The command exits non-zero when a message
+cannot be normalized (missing/unknown type, capitalized or overlong subject).
+
+## commit-msg hook
+
+To enforce the rules locally, install the hook:
+
+```sh
+make install-hooks
+# or manually:
+ln -sf ../../scripts/commit-msg.sh .git/hooks/commit-msg
+```
+
+The hook normalizes your message file in place before the commit is created and
+rejects messages that cannot be fixed automatically. Bypass it with
+`git commit --no-verify`.